effect of different polymeric films on the storage life of tray packed pear fruits

EFFECT OF DIFFERENT POLYMERIC FILMS ON THE STORAGE LIFE OF TRAY PACKED PEAR

FRUITS

Thesis Submitted to the Punjab Agricultural University

in partial fulfilment of the requirementsfor the degree of

MASTER OF SCIENCE

in

POMOLOGY

(Minor Subject: Botany)

By

Dinesh Kumar(L-2006/07-A-60-M)

Department of Horticulture College of Agriculture

©PUNJAB AGRICULTURAL UNIVERSITYLUDHIANA-141004

2009

CONTENTS

Chapter Topic Page

I INTRODUCTION 1-3

II REVIEW OF LITERATURE 4-16

III MATERIALS AND METHODS 17-21

IV RESULTS AND DISCUSSION 22-52

V SUMMARY 53-55

REFERENCES 56-64

23

Title of the Thesis : “Effect of different polymeric films on the storage life of tray packed pear fruits”

Name of the Student : Dinesh Kumarand Admission No. L-2006/07-A-60-M

Major Subject : Pomology

Minor Subject : Botany

Name and Designation : Dr. B.V.C Mahajanof Major Advisor Senior Horticulturist Department of Horticulture

Degree to be Awarded : M.Sc.

Year of award of Degree : 2009

Total Pages in Thesis : 64+Vita

Name of University : Punjab Agricultural University, Ludhiana – 141004, Punjab, India

ABSTRACT

The present investigations entitled “Effect of different polymeric films on the storage life of tray packed pear fruits” were conducted in the Department of Horticulture and Punjab Horticultural Post Harvest Technology Centre, PAU Campus, Ludhiana during the year 2007 and 2008. Fruits of pear cv. Patharnakh were harvested at physiological maturity; packed in trays and seal wrapped in commercially available films viz. Shrink, Cling, LDPE and HDPE films. The fruits were stored at 20±1°C and 90-95% RH (Super market conditions) and at ambient conditions (30-320C and 75-80% RH). At 20±10C temperature, the fruits packed in different films registered minimum PLW, lower firmness breakdown, negligible spoilage and higher acidity, better colour development and sensory quality as compared to control fruits. On the other hand, the TSS, total sugars, reducing sugars and non reducing sugars increased up to 21 days of storage at 20±1°C in film packed fruits, while in control these constituents increased up to 14 days. Among different films, fruits packed in Shrink films maintained lower PLW, desirable firmness, excellent colour and sensory quality followed by Cling films. Under ambient temperature conditions, control fruits showed better quality as compared to polyethylene film packed fruits. From the present investigations it can be concluded that under super market conditions of 20±1°C and 90-95% RH the pear fruits packed in Shrink film can be stored for 3 weeks as compared to control fruits which maintained storage life of 2 weeks. While under ambient temperature conditions, the packaging of fruits in polyethylene film is not recommended due to build up of high condensation and abnormal gas atmosphere in the package.

Keywords: Pear, Shrink film, Cling film, LDPE film, HDPE film, temperature, storage, quality

24

Chapter-I

INTRODUCTION

Pear is an edible pome fruit which belongs to the genus Pyrus and is native to coastal

and mildly temperate regions of the western Europe and north Africa, right across Asia. They

are medium sized trees, reaching 10-17 m tall, often with a tall, narrow crown. The pear fruit

in most wild species is 1-4 cm in diameter, but in cultivated, its size is up to 18 cm long and 8

cm broad. The shape varies in most species from oblate to globose, to the classic pyriform

‘pear- shape’ of the European pear with an elongated basal portion and a bulbous end.

It is also grown under sub-tropical conditions because of its wider climatic and soil

adaptability. It can tolerate temperature ranging from -260C during dormancy to 450C during

growing season. Generally, Patharnakh requires approximately 250 chilling hours below 70C

to adequately break dormancy of flower buds but the chilling hours range may vary for

different varieties of Asian and European pear.

As per the composition 200 gm pulp contains 122 cal of energy, 26 mg of

potassium, 16 mg of calcium, 4 mg of sodium and 30.8 mg of carbohydrates

(Ensminger 1983). A variety of products like jam, jelly, murabba, nectar and squash

can be prepared from pear. There is a great scope for increasing area under this fruit

due to high productivity, good eating and keeping quality, high nutritional value and

high degree of adaptability under different agro climatic conditions.

Pears are grown in all continents of the world. In India, it occupies an area of

38,600 hectares with an annual production of 1.76 lakh MT (Anon 2006 a). It is

commercially grown in states of Jammu & Kashmir, Himachal Pradesh, Uttaranchal,

Punjab, Haryana and some parts of Nilgiri Hills and Assam. In Punjab, it occupies

an area of about 2560 ha with 51200 MT production and ranked fifth after citrus,

mango, guava, and ber (Anon. 2006 b). It is mainly grown in districts of Jalandhar,

Gurdaspur, Amritsar, Hoshiarpur and Ropar. Pear varieties grown in Punjab are

Patharnakh, Punjab Gold, Punjab Nectar, Punjab Beauty, Baggugosha, LeConte, etc

but Patharnakh (Pyrus pyrifolia Burm. (Nakai)) is the leading cultivar due to its

hardy nature and wider adaptability to different climatic and soil conditions. It

occupies more than 70% of area under pear cultivation. The fruits of this cultivar are

liked very much by the consumers due to its juicy pulp and crisp texture after

adequate ripening.

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The harvesting of Patharnakh pear starts in the third week of July and

continues up to the end of August. Generally, this period coincides with high

rainfall and high temperature, which interferes with post harvest quality and

marketability of fruits. Therefore, the farmers are forced to sell their produce during

this period at a throw away prices due to non- availability of adequate post harvest

infrastructure, which creates glut in the market, resulting in huge post harvest

losses.

The bulk of fruits of this cultivar produced in Punjab is either marketed in

gunny bags or loose or sometimes in wooden boxes, thus fetches lower prices in the

markets. The pear fruit, however can make more profits, if handled properly at retail

end.

The role of packaging for horticultural produce seems to be still

underestimated. Packaging of fresh fruits is essential in the whole distribution cycle,

starting from producer to the final user. The use of improper packaging may cause

mechanical damage or loss of product freshness. The properly packed product

creates demand in the market, because it adds value to the commodity during

marketing.

The basic principal of packaging technology is that once produce is placed

in a package and hermetically sealed, an environment different from ambient

conditions will be established inside the package such as high CO 2 and low oxygen

which helps in maintaining the quality and increase the shelf life (Hardenburg,

1971). The key to successful use of this technology is to know what type of

environment will be most beneficial to the produce inside the package and then

determining which packaging materials should be used to create such an

environment. Correct application of this technology can significantly extend the

shelf life of fresh produce but, if incorrect packaging materials are chosen,

atmospheric conditions which are injurious may be generated and this can actually

result in shorter shelf life.

Therefore, there is a need to improve the packaging systems especially for

retail marketing of pear fruits after harvest, so that quality fruit is made available to

the consumers in domestic and distant markets. Hence the present investigation is

planned with the following objectives:

26

1. To study the effect of polymeric films on the storage life and quality of pear

fruits under super market condition i.e. at 20±1°C temperature.

2. To study the effect of polymeric films on the storage life and quality of pear

fruits under ordinary market condition i.e. at ambient temperature.

27

Chapter-II

REVIEW OF LITERATURE

2.1 Role of packaging film in horticulture crops

Packaging of fruits is to assemble the produce in convenient units to protect it from

deterioration during its handling from farm gate to consumer’s house. Adequate and proper

packaging protects the fruits from physical (firmness), physiological (weight) and pathological

(decay) deterioration. Out of various packaging materials like natural fiber sacs, gunny bags,

corrugated fiber board boxes; use of plastics is very pronounced for packaging of fruits with a

purpose to extend their storage life. Storing fruits in plastic films or bags creates modified

atmospheric conditions around the produce which allows lower degree control of gases (CO 2 and

O2) and can interplay with physiological processes of commodity (Zagory and Kader, 1988). The

present review of literature aims to provide concise information about modified atmosphere

packaging of fruits.

2.1.1 Modified Atmosphere Packaging (MAP)

Modified atmosphere packaging refers to the development of modified atmosphere

around the fruits through the use of polymeric films. MAP is important for the fresh produce

because of their high respiration rates, enhanced ethylene biosynthesis and susceptibility to water

loss and microbial growth (Gorny, 1997). The commercial use of this technology provides us

means to slow the process of ripening and senescence by retarding the rate of respiration,

transpiration, ethylene evolution; reduced microbial contamination and subsequently resulting in

better quality retention during storage, transport and marketing.

MAP has been reported to increase the shelf life and maintain the quality of several

commercially important fruits viz. apricot (Pretel et al 2000), avocado (Chaplin and Hawson,

1981), litchi (Paull and Chen, 1987) and mango (Neeraj et al, 2003). MA packaging retarded

softening in pear fruits (Smith et al, 1991). Zora et al (2000) reported improved quality and

prolonged shelf life of mangoes when MAP was combined with post harvest calcium treatments.

2.1.2 Plastic material used for packaging

Earliest report on use of plastics is by using cellophane bags and pliofilm respectively,

for extending shelf life of apples and also use moisture proof cellulose sheets to prevent

shriveling of Golden Delicious apples in cold storage (Neeraj et al, 2003).

28

With advancement in technology different types of plastic bags, wraps, films were

reported to be used by various workers to extend the shelf life of different fruits viz. semi

moisture proof cellophane bags for grapes, polyolefin film for grape-fruits, polyethylene seal

packaging for oranges, pear (Sandhu and Singh, 2000). Individual polyethylene wrapping of

kinnow fruits exhibited extended storage life with better quality retention as compared to

unpacked control fruits (Kumar et al, 2000).

Many other type of plastic material like polylon net and PVC film for mango (Yantarasri

et al, 1995), polypropylene box lined CFB boxes and polypropylene box liners for apples

(Geeson et al, 1994), paper-pulp trays sealed with plastic film, polypropylene, polyethylene bags

and polyvinylidene chloride (PVDC) film for peach (Neeraj et al, 2003) have been reported to

maintain the quality.

2.1.3 Packaging in polyethylene bags

Many scientists reported that polyethylene bags were more suitable for pre-packaging of

fruits than polyvinyl chloride, polypropylene and polystyrene bags (Honda and Ishiguro, 1968).

Ben Yehoshua (1979) reported that packaging with high density polyethylene (HDPE) doubles

the storage life of citrus fruits. Overall market quality of Eureka lemons was higher in HDPE

sealed bags (Cohen et al, 1990). Shelf life of ber could be extended up to 22 days by packaging in

polyethylene bags (Baviskar et al, 1995). Narayana et al (1991) reported usefulness of high

molecular high density (HMHD) polyethylene for extending storage life of mango fruits. Geeson

et al (1991) reported four days extended shelf life of pear fruits packed in LDPE bags. Chamara

et al (2000) reported that mature ‘Kolikuttu’ bananas packed under modified atmosphere

conditions using LDPE bags (0.075mm) could be stored for 24 days at 14° C and 94% RH with

excellent quality.

Use of perforated plastic bags and perforated LDPE bags for mango (Narayana et al,

1991), perforated polyethylene bags for litchi (Kahlon and Bajwa, 1991) effectively increased the

shelf life of stored produce. A minimum of two weeks was required by mango fruits packed in

perforated PVC film for proper peel color development (Sornsrivichai et al, 2002).Smith et al

(1987) studied the effects of LDPE packs on primary quality attributes viz. skin colour, flesh

firmness and sensory quality of Discovery apples held at 20°C and reported marked reduction in

softening and yellowing.

Noomhorn and Potey (1993) packed banana cv. ‘Klua Hom Tong’ in polyethylene films

followed by storage at 23° C and reported the extension in the shelf life up to 22 days. Kahlon

and Uppal (2005) reported that the shelf life of mango cv. Chausa could be extended up to 15

29

days at a temperature of 28-33° C and 85-90% RH after treating with GA 3 (2000 ppm) followed

by packaging in perforated polythene bags. The TSS and reducing sugars increased up to 15 days

and decreased thereafter, while acidity level of the fruits decreased throughout the storage period.

Hussain et al (2004) conducted a 45 days storage experiment to investigate the effect of

Uni-Packaging with polyethylene on citrus fruits and observed significant effect in prolonging the

shelf life and maintenance of external appearance, taste, and texture. Deshpande and Shukla

(2008) used low-density polyethylene (LDPE) 25 µ, 50 µ and 75 µ and polypropylene (PP) 25 µ

and 38 µ for packaging of grapes for short-term storage under ambient conditions and reported

the acceptability of grapes up to the period of 7 days with no colour change and no mould

growth/ fungal attack.

Singh and Sudhakar Rao (2005) reported that fresh mature green papaya (Carica papaya

L.) cv. ‘Solo’ fruits individually shrink wrapped with Cryovac D-955® film, could be kept well

for 10 days at ambient temperature that ripened in 5 days with firm texture and good flavour after

unwrapping. Rao et al (2000) reported maximum extension in the shelf life (24 days) of shrink

wrapped cucumbers, in addition to reduction in weight loss and maintenance of firmness during

storage. The optimum storage temperature for cucumbers shrink wrapped with PE and polyolefin

films was found to be 10°C and 15°C respectively.

Nain et al (2002) conducted an experiment of wrapping ‘Dashehari’ mangoes in cling

films and observed the favourable effect of the film in checking the physiological loss in weight

(PLW) and decay loss in fruits. They also reported better retention of acidity and ascorbic acid

content in cling film wrapped fruits. Ayhan et al (2008) investigated the effect of modified

atmosphere packaging on the quality and shelf life of minimally processed carrots cv. Nantes

during cold storage. The carrots packed with high oxygen and passive MAP retained quality

properties better compared to low oxygen. The whiteness index did not significantly change

during the 21 days of storage in all applications, indicating the good retention of orange color.

Neeraj et al (2004) studied the effect of HDPE, LDPP and PVC packaging on the

ascorbic acid content and decay loss during storage of aonla fruits cv. Chakaiya. After 30 days of

storage at room temperature, maximum retention of ascorbic acid and minimum fruit decay was

recorded in fruits packed in HDPE bags whereas minimum ascorbic acid and maximum decay

was observed in PVC bags packed fruits. The potential of 30 μ thickness High Density

Polyethylene (HDPE) bags with microperforations for maintaining the quality of ‘Kay’ acid lime

fruits during storage at 10 and 20 ºC was studied by Ramin and Khoshbakhat (2008). The

greenest and firmest fruits were found in microperforated polyethylene bags stored at 10ºC with

30

superior vitamin C and color value. Microperforation in polyethylene bags reduced remarkable

weight loss and decay in fruits.

2.1.4 Effect of plastic thickness

Apart from appropriate selection of packaging material, thickness of packaging material

i.e. thickness of plastic film is also of vital importance. Work was carried out by various research

workers to identify the suitable packaging material with appropriate thickness for different fruits

under specific temperature and storage conditions viz. 0.03mm polypropylene bags and 0.01mm

PVC bags for mango (Sornsrivichai et al, 1992), 0.05 mm shrinkable polyethylene films for

papaya (Lazan et al, 1993).

Seal packaging of papaya in three layers of LDPE (0.0125mm thick) and stored at 24-

280C for 18 days retarded the peel color development and fruit softening (Lazan et al, 1990).

Polyethylene bags have been found suitable for extending shelf life of guava (Bhullar and

Farmahan, 1980). Storage life of guava was extended up to 7 days over control fruits by

packaging in 300 gauge polyethylene bags with no ventilation (Venkatesha and Reddy, 1994).

The guava fruits stored in 600 gauge LDPE bags had the highest organoleptic score and good

marketability up to 10 days of storage (Adsule and Tandon, 1983). Perforated polyethylene bags

(100 gauge) with 1.2% ventilation for sapota and polyethylene bags (200 gauge) with 0.5%

ventilation for mango has been used successfully to extend the shelf life.

The above presented information about plastics as fruit packaging material clearly

indicates its role in post-harvest technology. Its ability to create modified micro-environment

(CO2, O2, humidity) around the packed produce gives it a unique place in packaging industry.

Plastics like polyvinyl chloride, polyethylene, polypropylene bags and films (high density, low

density, perforated and non-perforated) has proved to be an effective measure to extend the shelf

life of fruits like apple, pear, banana, guava, kinnow, mango, etc (Neeeraj et al, 2003).

The literature pertaining to the effect of different polymeric films on the storage

life of tray packed pear fruits has been reviewed under the following heads.

2. 2 PHYSICAL CHARACTERS

2.2.1 Physiological loss in weight (PLW %)

2.2.2 Fruit firmness (Kgf)

2.2.3 Spoilage (%)

2.2.4 Sensory quality (Hedonic scale 1-9)

2.2.5 Fruit colour

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2.3 CHEMICAL CHARACTERS

2.3.1 Total soluble solids (%)

2.3.2 Titrable acidity (%)

2.3.3 Sugars (%)

2. 2 PHYSICAL CHARACTERS

2.2.1 Physiological loss in weight (%)

Park et al (1970) reported that pear fruits packed in polyethylene film markedly

delayed ripening, preserved freshness and reduced weight loss, spoilage, core browning

and biochemical components of fruits during storage. Minimum loss in weight in fruits

of Patharnakh pear was recorded with polythene wrappings (Randhawa et al 1982).

Masoodi and Mir (1995) noted minimum weight loss and firmness breakdown of William

pear in HDPE bags after treating with calcium chloride. Mohla et al (2005) conducted an

experiment in which Patharnakh pear fruits were stored under ambient conditions after wrapping

individually in HDPE, LDPE, newspaper, tissue paper and paddy straw and found that PLW and

spoilage losses were minimum in HDPE (20 µm) wrapped fruits, which were considered of

acceptable quality even after 45 days storage.

Baccaunaud (1989) suggested that packaging of fruits of apples and pears in polythene

film reduced weight loss and maintained their quality in fresh conditions.

Gilfilian (1985) compared unwaxed Valencia oranges wrapped in high density

polyethylene (HDPE) film or low density polyethylene (LDPE) with those of conventionally

waxed and tissue paper wrapped fruits, and observed that weight loss of film wrapped fruits was

minimum compared with conventionally waxed fruits.

Gonzalez et al (1990) reported delayed fruit ripening and reduced weight losses up to 4

weeks, after individually packed mango fruit (cv. Keitt) in low and high density polyethylene

films (LDPE and HDPE) and kept at 20°C and 67% RH.

Sonkar and Ladaniya (1998) reported that PLW was significantly reduced by wrapping

the Nagpur mandarin fruits in trays with heat shrinkable and stretch cling polythene films.

Mootoo (1992) reported a decrease in weight loss and spoilage of orange cv. Jaffa after

individually wrapping the fruits in polyethylene films at 150C and under ambient temperature

conditions.

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Batagurki et al (1995) investigated the effect of individual packaging of mangoes in two

polymeric films (with and without perforations) for short-term storage at ambient temperature of

21-24ºC and reported that mangoes packed in perforated Cryovac bags were found to have better

quality than those in E50 bags. The physiological losses in weight in packed mangoes were 1.64-

2.98 per cent as compared to 11.50-17.0 per cent in non-packed fruits up to 10 days of storage.

Fruits of mango cv. ‘Tommy Atkins’ individually seal packed in heat shrinkable plastic film were

stored for 2 weeks at 120C and then ripened at 210C. Weight loss of film sealed fruits was

significantly less as compared to that of unsealed fruits (Miller et al 1983). Mango fruits cv.

Dushehari packed in 200 gauge polythene bags having 0.6% perforation followed by storage at

room temperature showed lower weight loss and better retention of Vit. C (Garg et al, 1971).

Bhullar et al (1984) reported that wrapping of Langra and Dusheri mango fruits with various

wrappers increased the shelf life, up to 10 days under ambient storage conditions. It was noticed

that the loss in weight was the minimum in case of perforated polythene bags alone and in

combination with fungicidal wax.

Sornsrivichai et al (1986) conducted an experiment with 3 types of polymeric films

namely Polyethylene (PE), Polyvinyl chloride (PVC) and Polypropylene (PP) on storage life and

qualities of Kwaw Sawoey mango and reported that PE package is the best in preventing fruit

weight loss.

Siddiqui and Gupta (1997) conducted an experiment on guava cv. Allahabad safeda and

reported that throughout the storage period; lowest physiological loss in weight was recorded in

polyethylene wrapped fruits. Kumar et al (1998) reported that individually polyethylene packed

guava fruits showed minimum physiological loss in weight on all periods of storage. Kumar et al

(2003) confirmed that all polythenes were effective in checking the PLW and maintaining the

quality of Sardar guava during ambient storage.

Özkaya and Dündar (2008) reported that packaging in plastic films could be useful for

short-term storage of nectarines cv. Maria Aurelia for reducing the weight losses and maintaining

the quality parameters for 10 days.

Nanda et al (2001) conducting experiment on pomegranate cv. Ganesh and observed that

the shelf life of fruits can be extended up to 12 weeks with a minimum loss in weight when fruits

are wrapped in shrink films.

2.2.2 Fruit Firmness

Masoodi and Mir (1995) noted minimum firmness breakdown of William pear in HDPE

bags after treating with calcium chloride. Passam (1982) reported that mango cultivars packed

33

individually in polythene bags, resulted in higher fruit firmness, texture and extended the storage

life by 8-10 days under ambient conditions.

Ben- Yehoshua (1967 and 1969) reported that an aqueous suspension of high density

polyethylene film called “Tag” delayed deterioration of fruits better than waxes. Dhatt et al

(1991) observed that seal packaging the kinnow fruits individually in 0.1 mm thick high density

polyethylene film maintained acceptable firmness up to 8 weeks of storage.

Banana packed in sealed polyethylene bags remain in hard green conditions whereas the

non packed fruit ripened (Scott et al, 1971).

Miller et al (1986) wrapped the mango fruits in 2 types of plastic films and observed no

significant difference in weight loss, peel colour, pulp colour, firmness and decay up to 26 days

of storage.

Heaton et al (1990) observed a loss of crispness which being the primary limiting factor

to extend storage life after storing the apple fruits in shrink wrapping packaging.

Nanda et al (2001) while working on pomegranate fruits cv. Ganesh reported that the

fruits wrapped in shrink film retain their freshness and firmness to a greater extent than the fruits

coated with sucrose polyester as well as unwrapped fruits.

2.2.3 Spoilage (%)

Pear fruits packed in polythene film registered reduced spoilage and core browning

during storage (Park et al, 1970). Similarly, Packham’s Triumph pears were stored at 300F in all

round waxed paper liner or polyethylene bags. The latter method prevented wilting and reduced

rots, internal browning and scald (Padfield et al, 1971). Eksteen et al (1977) noticed CO2 injury in

Willian Ben Chretan and Burre Hardy pears packed in perforated polyethylene bags and stored at

low temperature.

Rameshwar et al (1979) reported the use of film wrapping with ethylene absorbent for

extending the storage life of mangoes. Fruits were wrapped in 200 gauge polyethylene bags with

0.4% ventilation. It was found that film wrapping without ventilation resulted in more spoilage

due to greater incidence of disease.

Yantarasri et al (1995) reported that the fruits wrapped in polystyrene trays (3

fruits/pack) with perforation area of 7 percent and stored at 20ºC resulted in uniform ripening,

prevented rotting and off flavour in stored fruits of cv.‘Nam Dok Mai’ mangoes. Non-perforated

sealed mangoes had over ripening, rotting and resulted in off flavour.

34

McCollum et al (1992) evaluated the effects of individual shrink film wrapping (60

gauge) on shelf-life and quality of mangoes, and observed that wrapped fruits showed more decay

than non-wrapped one.

Yuen et al (1993) reported that wrapping of mango fruits of cv. ‘Kensington Pride’ in

sealed polybags or in cling or shrink-wraps significantly delayed the ripening without much

spoilage and maintained attractive appearance.

Severity of post-harvest fungal rot was significantly reduced by wrapping the fruits in

plastic film than control on 5th day of inoculation. The results of the investigation suggested that

plastic film wrapping effectively reduced the development of various rots (Chandra and Pathak

1992).

Modified atmosphere storage using perforated plastic film packagings are used to

maintain the quality of ‘Nam Dok Mai’ mangoes for the overseas shipment. The fruit shipped in

perforated packages had an additional one week of shelf- life with better quality and lower

percentage of rotting under ambient temperature (Sornsrivichai et al 1998).

The least rotting (3.33%) and best appearance at the end of storage were recorded from

the mango fruits packed in perforated polythene bags (Bhullar et al, 1984).

Ben Yehoshua (1978) made an attempt to seal the fruit in plastic film of high density

polyethylene (HDPE) and showed that transpiration was reduced 5 to 20 times by sealing fruits in

10 µm. Unlike waxing the film formed a barrier increasing markedly the resistance to water

vapour, thus, less chances of spoilage. He further observed that individual seal packaging of fruits

of orange cvs Shamouti and Valencia, Marsh grapefruit and lemon Eureka with a film of HDPE

(0.1mm), markedly delayed deterioration as measured by peel shrinkage, softening with sodium

orthophenylphenate.

Rameshwar et al (1979) investigated the use of film wrapping with ethylene absorbent

for extending the storage life of mangoes and reported that fruits wrapped in 200 gauge

polyethylene bags with 0.4 per cent ventilation plus ethylene absorbent resulted in more spoilage

due to greater incidence of disease. Stem end rot was found to be major disease in wrapped

mangoes and also color development was slower.

Gilfilian (1985) reported that fruits of Navel oranges, Marsh grapefruit and Valencia

oranges stored for 4 to 8 weeks in polyethylene bags delayed the attack of Diplodia natalensis

and Alternaria citrii than the unwrapped fruits. Seal packaging reduced the decay of cv. Marsh

grapefruit but slightly enhanced the decay of Valencia oranges compared with conventionally

35

handled fruits. Wrapping of individual fruit resulted in less decay than sealing a whole carton of

fruit together. (Ben- Yehoshua et al, 1983).

Kupferman and Sanderson (2001) observed that polymeric film packaging lengthened the

postharvest life of cherry fruit by reducing the rate of growth of decay organisms, retarding

softening and retaining stem color.

Singh et al (1988) treated kinnow fruits with fungicides and wax emulsion and stored

them at 12-140C after packing in ventilated polyethylene bags. It was observed that rotting was

more in untreated fruits than those treated with different concentration of fungicides or wax

emulsion.

2.2.4 Sensory quality (Hedonic scale 1-9)

Miller et al (1986) reported that off flavour in film wrapped fruits might be related to

excessive levels of CO2 and reduce levels of O2. It was found that mangoes shrink-wrapped in

HDPE at soft ripe stage had off flavour and elevated CO2 levels after 9 days of storage.

Yuen et al (1993) reported that wrapping of mango fruits of cv. ‘Kensington pride’ in

sealed polybags or in cling or shrink wraps significantly maintained attractive appearance with

eating quality upto 10th day of storage.

Tsuda et al (1999) conducted investigation on the effects of packaging on ‘Carabao’

mangoes, imported from Philippines to Japan. These workers observed that shriveling did not

occur and fruits maintained attractive appearance when these were packed in perforated polythene

bags and stored at 200C. Ben- Yehoshua (1978) reported that seal packaging significantly delays

the off flavor of the fruits. He observed that after two months of storage at 170C and 90% RH non

sealed Valencia oranges had developed off flavor and poor organoleptic properties, while sealed

fruits retained its normal flavor and eating quality for much longer duration.

Sonkar and Ladaniya (1998) reported that Nagpur mandarin fruits packed in stretch cling

film had significantly higher flavour score and better acceptability and freshness than non

wrapped fruits after 60 days of storage. Dhatt et al (1991) found that individually wrapped

kinnow fruits in high density polyethylene film were judged tasty after 8 weeks of storage as

compared to non- sealed that became inedible due to off flavor.

Ben- Yehoshua et al (1979) observed that individual seal packaging of orange cv.

Shamouti and Valencia, Grapefruit cv. Marsh and lemon cv. Eureka with high density

polyethylene (HDPE) maintained the fresh appearance of fruit more than twice as long as

conventionally handled fruits.

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Conference pear packed in low density polyethylene (LDPE) films retarded the rate of

flesh softening but normal sweetness, aromatic flavor and succulent juicy texture maintained after

4 days (Geeson et al, 1991).

Heaton et al (1990) reported that the apple fruits cv. Starcrimson showed acceptable

qualities for a period of 38 weeks while packed in shrink wrap packaging followed by storage at

260C, 40-42% RH.

2.2.5 Fruit colour

Packaging of fruits in different wrappers had a positive effect on their color under

ambient and refrigerated conditions. Encouraging results were obtained by the use of polythene

liners by several investigators. The effect of high density polyethylene sealing on lemons

showed color improvement in mature green picked fruits which were better during 3 months of

storage than unsealed one (Cohen et al, 1986). Sweet orange cv. Mosambi wrapped in

polythene bags showed better color development as compared to non wrapped fruits (Tarkase et

al, 1989).

Tugwell et al (1988) observed that fruits of Valencia orange harvested before December

and wrapped in plastic films retained a bright orange color and can be stored without refrigeration

for marketing up to 3 months. Fruits stored at 100C were brighter in color than wrapped fruits at

ambient temperature.

Miller et al (1986) concluded that mango fruit cv ‘Tommy Atkins’ wrapped in plastic

film developed less yellow color and pulp at soft ripeness than non wrapped fruits held in storage

at 210C. Litchi fruits packed in 0.04 mm polyethylene bags retained their fresh red color during 8

days storage (Zhang et al, 1986).

Wavhal and Athale (1988) reported 20 days of storage life in cv. ‘Kesar’ treated with

NAA (200ppm) in perforated polythene bags of 100 gauge thickness. They observed attractive

color of both skin and pulp and good appearance of fruits. The shelf-life of fruits was effectively

prolonged by about 8 to 10 days.

Batu and Thompson (1998) reported that sealed packaging of tomatoes cv. ‘Liberty’ with

polyethylene and polypropylene films, delayed the development of the red colour until 30 days of

storage and fruits were also still very firm even after 60 days of storage. Tomatoes sealed within

PE and PP films had also the lowest weight loss and the highest soluble solids after 60 days of

storage.

37

2.3 CHEMICAL PARAMETERS

2.3.1 Total soluble solids (%)

Bhullar (1966) reported that wrapping of ‘Dusehri’ mango fruits with various wrappers

significantly increased the shelf- life under ambient storage conditions. The use of perforated

polythene in combination with wax coating resulted in significantly less total soluble solids, thus

found helpful in prolonging the storage life.

Singh et al (1967) reported that fruits of ‘Dusehri’ mango were in good condition after 14

days of storage when these were packed in perforated polythene. The polythene packing

treatment resulted in low total soluble solids content over the control fruits.

Rameshwar et al (1979) reported the use of film wrapping with ethylene absorbent

(potassium permanganate) for extending the storage life of mangoes.. Fruits were wrapped in 200

gauge polyethylene bags with 0.4 per cent ventilation plus ethylene absorbent (potassium

permanganate). Film wrapping resulted in increase in TSS at slower rate and had less TSS over

control fruits.

Narayana et al (1991) investigated the use of HDPE films (10, 15, 25, and 32.5µ

thickness) on storage of mango fruits. All the wrapped fruits were green and extent of greenness

was directly proportional to thickness of the film, while non-wrapped fruits had considerable

ripening. The total soluble solids content increased at a slower rate in wrapped fruits than control

fruits.

Dhatt et al (1991) while working on seal packing of kinnow in high density polyethylene

film reported slight reduction in total soluble solids during storage under different sealing

methods. They observed that after 4 weeks of storage soluble solids increased in non sealed fruits,

but this trend was reversed after 8 weeks of storage when higher soluble solids were observed in

all types of wrapped fruits, whereas non sealed fruits completely shriveled and had dried peel.

After 12 weeks storage not much difference in TSS was observed under different sealing

methods.

Dhillon et al (1977) treated the kinnow fruits and kept the fruits in cold store after

packing in perforated and non perforated polythene bags. They observed significantly higher

percentage of total soluble solids in untreated fruits and minimum TSS in the fruits treated with

wax and wax+ Benlate. They further observed that the fruits packed in perforated polythene bags

showed more TSS than those packed in non perforated ones.

38

Cohen et al (1983) reported that individual sealing of lemons in high density

polyethylene film intermittently prolonged the shelf life. The juice content percentage during

storage and shelf life was influenced by storage period of three months, the shelf life, juice and

acid content of fruits stored at 130C increased while at 80C the increase was little. Later on Cohen

et al (1990) stored lemons after packing them individually in HDPE. They recorded an increase in

juice percent from fruits wrapped in paddy straw after 85 days of storage at 0-3.30C temperature.

Neeraj et al (2002) reported that guava fruits packed in polyethylene bags retained

maximum TSS as compared to control after 9 days of storage.

2.3.2 Titratable Acidity (%)

There was better retention of acidity and vitamin C in perforated polythene

packed ‘Dusehari’ mango fruits. Packing resulted in decreased respiration and prolonged shelf-

life over control (Garg et al 1971).

The acidity decreased faster in film packed fruits and stored at room temperature (Gorini

and Testoni, 1988). Rameshwar et al (1979) reported that film wrapped fruits showed the slower

loss of acidity during storage over control.

McCollum et al (1992) reported the effects of individual shrink wrapping (60 gauge) on

shelf-life and quality of mangoes and observed that the wrapped fruits were significantly more

acidic than non-wrapped fruits, as indicated by lower pH value.

Sagar and Khurdiya (1996) reported that fully matured and unripe ‘Dusehri’ mangoes

wrapped with newspaper and polythene film showed slower decrease in acidity, firmness and

specific gravity at ambient temperature at each successive stage of storage interval as compared

to non- wrapped fruits.

Kaur et al (2005) reported a slower decrease in acidity after treating fruits with calcium

chloride and then individually wrapped the fruits in different wrappers, viz. newspaper,

polyethylene and butter paper.

Mohla et al (2005)while working on sand pear by using different packing materials

observed a decrease in titratable acidity and reported that fruits can be stored up to 45 days.

Kinnow fruits individually seal packed in high density polyethylene film and tightly

sealed with manual electric sealer showed maximum acidity percentage after 4 weeks of storage

but it decreased considerably between 8-12 weeks of storage interval (Dhatt et al, 1991).

39

2.3.3 Sugars (%)

Dhillon et al (1977) found that the amount of total sugar in the Mango packed in

perforated polythene bags was the highest as compared to non perforated ones were used.

Angadi and Krishnamurthy, (1992) treated freshly harvested kinnow fruits with 3%

waxol, packed in ventilated polythene bags. Fruits were stored at room temperature (250C) or at

low temperature (100C). They observed the highest total sugars after 19 days of storage at room

temperature.

Sagar and Khurdiya (1996) reported that fully matured and unripe ‘Dusehri’ mangoes

were wrapped with newspaper and polythene film. The fruits were kept under ambient

temperature (33-35.5ºC). At each successive stage of storage interval the reducing and total

sugars were found to increase at lower rate than in control fruits.

Singh et al (1998) studied the effect of perforated polythene wrapping and pre-harvest

application of calcium compounds on storage life of mango cv. ‘Amrapali’. Perforated polythene

wrapping, calcium chloride (1.5%) and calcium nitrate (1.5%) were found most effective

treatments. These maintained the minimum reducing and total sugars and maintained the storage

life of fruits significantly over control.

Mohla et al (2005) reported an increase in total and reducing sugars with the

advancement of storage interval in sand pear as a result of different packing materials like high

density polyethylene, low density polyethylene, newspaper, tissue paper and paddy straw.

Kaur et al (2005) while working on pear cv. Baggugosha by using different concentration

of calcium chloride (4, 6 and 8%) and thereafter, individually wrapping in different wrappers, viz.

newspaper, polyethylene and butter paper and reported an increase in total and reducing sugars

and the fruits can be stored economically at ambient temperature up to 18 days.

40

Chapter-III

MATERIALS AND METHODS

The present investigations entitled, “Effect of different polymeric films on the storage life of

tray packed pear fruits” were conducted in the Department of Horticulture and Punjab

Horticultural Postharvest Technology Centre, Punjab Agricultural University, Ludhiana

during the year 2007 and 2008.

The experiment was conducted on 15 year old trees of Patharnakh cultivar growing in

the new orchard. The experimental trees were given uniform cultural practices as per PAU

recommendations.

3.1 Preparation of fruit samples

The pear fruits of uniform size, disease and bruise free were picked randomly from

all the four directions of the plants with the help of secateur. The fruits were collected in

plastic crates and shifted to Punjab Horticultural Postharvest Technology Centre. In the

laboratory, the fruits were sorted and graded washed with chlorine solution (100 ppm).

Thereafter fruits were divided into requisite lot for further handling.

3.2 Packaging material

3.2.1 Corrugated tray

The corrugated tray measuring 22 cm × 13 cm was used for packing of pear fruits

3.2.2 Polymeric films

In the present studies, 4 types of polymeric films commercially available in the

market were tried for packaging of pear fruits in corrugated trays. These were Low Density

Polyethylene (25µm), High Density Polyethylene (20µm), Shrink film (10µm) and Cling film

(20µm).

3.3 Method of packaging

Pear fruits were packed in trays and over-wrapped tightly in pouches of different

polymeric films. However, the shrink film wrapped packs were passed through a shrink

wrapping machine (Model BS-450 shrink packing machine, Samrath Engineers, India) at 165

ºC for 10 seconds

41

3.4 Experimental details

3.4.1 Experiment 1. Effect of different polymeric films on the storage life of tray

packed pear fruits at 20±1°C and 90-95% RH.

Serial No. Treatments

T1 Tray packing in LDPE film

T2 Tray packing in HDPE film

T3 Tray packing in Shrink film

T4 Tray packing in Cling film

T5 Control

Treatments 5

Replications 3 (6 fruits in each replication)

Storage Intervals 4 (7, 14, 21 and 28 days interval)

3.4.2 Experiment 2. Effect of different polymeric films on the storage life of tray

packed pear fruits at ambient temperature conditions (30-320C and 75-80% RH).

Serial No. Treatments

T1 Tray packing in LDPE film

T2 Tray packing in HDPE film

T3 Tray packing in Shrink film

T4 Tray packing in Cling film

T5 Control

Treatments 5

Replications 3 (6 fruits in each replication)

Storage Intervals 3 (3, 6 and 9 days interval)

In each packed tray, four pin holes were made to provide ventilation for better storage condition.

3.5 Observations recorded:

The following physical and chemical changes were observed during ambient and cold

storage studies.

42

3.5.1 Physical parameters

3.5.1.1 Physiological loss in weight (%)

The per cent loss in weight after each storage interval was calculated by subtracting final

weight from the initial weight of the fruits and then converted into percentage value. The

cumulative loss in weight was calculated on fresh weight basis.

Initial fruit wt. - final fruit wt.

Physiological loss in weight (PLW %) = --------------------------------- ×100

Initial fruit wt.

3.5.1.2 Fruit firmness

Firmness of randomly selected fruits (three from each replication) was measured with the

help of a ‘pressure tester’ penetrometer (Model FT- 327, USA) using 8 mm stainless steel probe.

About 1 square centimeter of the skin in each fruit from the shoulder end on both sides were

removed with the help of peeler and firmness of pulp was recorded and expressed in terms of

pressure (Kg force).

3.5.1.3 Percent spoilage

Per cent fruit rot was calculated by counting the total number of fruits that had rotten at

each storage interval.

Number of rotten fruits

Per cent fruit rot = --------------------------------×100

Total number of fruits

3.5.1.4 Sensory quality

The fruits were rated for this character by a panel of five judges on the basis of external

appearance of fruits, texture, taste, and flavour. A nine point ‘Hedonic Scale’ described by

Amerine et al (1965) was used for its inference, as given below:

Score Acceptability

9 Extremely desirable

8 Very much desirable

7 Moderately desirable

43

6 Slightly desirable

5 Neither desirable nor undesirable

4 Slightly undesirable

3 Moderately undesirable

2 Very much undesirable

1 Extremely undesirable

3.5.1.5 Fruit colour

The colour of 10 randomly selected fruits from each treatment was noted with the help of

the Royal Horticultural Colour Chart (Wilson 1938).

3.5.2 Chemical parameters

3.5.2.1 Total soluble solids (%)

Total soluble solids (TSS) were determined from the juice at room temperature with the help of

hand refractometer (Model Erma, Japan) and expressed in percent. These readings were corrected

with the help of temperature correction chart at 200C temperature (AOAC, 1990).

3.5.2.2 Titratable acidity (%)

For recording the acid content, 2 ml of juice was diluted to 10 ml with distilled water and

titrated against 0.1 N sodium hydroxide solution using phenolphthalein as an indicator. The acid

content was expressed as using the following formula.

Volume of 0.1 N NaOH used Acidity (%) = 0.0067-------------------------------------------×100 Volume of juice taken

3.5.2.3 Sugars

The sugar content of the fruit was estimated with the method described by A.O.A.C.

(1990). A sample of 10 ml fruit juice was taken and diluted with distilled water. Extraneous

material was precipitated with the help of lead acetate. Excess of lead acetate was removed with

potassium oxalate. Thereafter, solution was filtered and volume was made 100 ml with distilled

water. This filtrate (aliquot) was kept for the estimation of reducing and non-reducing sugars.

a) Reducing sugars (%)

To determine the reducing sugars, the aliquot was titrated against boiling solution

mixture containing 5 ml each of Fehling’s solution A and B using methylene blue as indicator.

Titration was continued till brick red colour appeared. The results were expressed as per cent on

44

juice basis (AOAC 1990).

b) Total sugars (%)

Total sugars were estimated by taking 25 ml of above aliquot in 100 ml volumetric flask.

To this solution 5 ml 60 per cent HCl and 25 ml distilled water was added. It was allowed to

stand overnight for hydrolysis. The excess HCl was neutralized with saturated NaOH solution

and volume was made 100 ml with distilled water. Total sugars were than estimated by titrating

the boiling mixture containing 5 ml of each of Fehling’s solution A and B against hydrolyzed

aliquot, using methylene blue as an indicator. The unloading of titre was stopped on the

appearance of brick red colour. The values were expressed in per cent on fresh juice basis

(AOAC 1990).

c) Non- reducing sugars (%)

The non- reducing sugars was calculated by subtracting total sugars from reducing sugars

and multiplied by 0.95.

3.6 Statistical design

The data are analyzed statistically according to completely randomized design (Sharma,

1998).

45

Chapter-IV

RESULTS AND DISCUSSION

The present investigations on the “Effect of different polymeric films on the storage life

of tray packed pear fruits” were undertaken in the Department of Horticulture and Punjab

Horticultural Postharvest Technology Center, Punjab Agricultural University, Ludhiana. The

results obtained from the laboratory studies are presented and discussed in the light of

available literature in this chapter.

4.1 Physiological loss in weight (PLW)

The data on PLW of pear fruits packed in polymeric films and stored at 20±1 0C

temperature are presented in Table 1 and Figure 1. The various treatments showed a

significant difference among themselves with regard to PLW. The percent PLW, in

general, increased with the advancement of storage period rather slowly in the beginning

but at a faster pace as the storage period advanced. It was noticed that Shrink film packed

fruits recorded the lowest mean PLW (3.37%), followed by Cling film (3.72%) packed

fruits. The unpacked fruits showed the highest PLW (6.05%). The PLW of fruits packed

in Shrink film ranged between 1.15 to 6.02 percent from 7 to 28 days of storage as

compared to control where PLW was found to be the highest and ranged between 2.93 to

9.75 percent from 7 to 28 days of storage. The other treatments also showed significant

low PLW as compared to control. The interaction between treatments and storage

intervals was found to be significant.

The data on effect of various polymeric films on PLW of pear fruits at ambient

storage conditions are presented in Table 2 and Figure 2. The lowest mean PLW (2.60%)

was observed in fruits packed in Shrink film which was found to be statistically

significant as compared to other treatments. On the other hand, the highest mean PLW

(4.53%) was observed in control fruits. The interaction between treatments and storage

intervals was found to be significant. During different storage intervals, fruits packed in

shrink film registered the lowest weight loss ranged between 0.74 to 4.15 percent from 3 to

9 days of ambient storage, respectively as compared to control where PLW ranged from 2.50

to 6.50 percent during same storage intervals.

46

Table 1. Effect of different polymeric films on physiological loss in weight (%) in pear cv. Patharnakh at 20±10C temperature

Treatments

Days after Storage

0 7 14 21 28 Mean

Tray packing in LDPE 0.00 1.65 2.85 4.75 6.86 4.03

Tray packing in HDPE 0.00 1.94 3.10 5.04 7.23 4.33

Tray packing in Shrink film 0.00 1.15 2.20 4.10 6.02 3.37

Tray packing in Cling film 0.00 1.34 2.55 4.42 6.57 3.72

Control 0.00 2.93 4.78 6.72 9.75 6.05

Mean 0.00 1.80 3.10 5.01 7.29

CD at 5% level

Treatment =0.04

Storage interval =0.03

Treatment x Storage interval =0.08

47

Table 2. Effect of different polymeric films on physiological loss in weight (%) in pear cv. Patharnakh at ambient temperature

Treatments Days after Storage

0 3 6 9 Mean

Tray packing in LDPE 0.00 1.03 3.46 4.81 3.10

Tray packing in HDPE 0.00 1.25 3.73 5.10 3.36

Tray packing in Shrink film 0.00 0.74 2.90 4.15 2.60

Tray packing in Cling film 0.00 0.96 4.15 4.45 3.19

Control 0.00 2.50 4.60 6.50 4.53

Mean 0.00 1.30 3.77 5.00

CD at 5% level

Treatment =0.05



48

The control fruits under both the temperature conditions exhibited the highest

physiological loss in weight as compared to film packed fruits, which might be due to exposure of

fruit surface to the open atmosphere resulting in higher rate of transpiration and respiration

thereby leading to higher physiological loss in weight. On the other hand, the fruits packed in

different polymeric films recorded lower weight loss, which is obvious due to role of films in

checking rate of transpiration/respiration and maintaining higher humidity inside the wrappers

(Ben Yehoshua, 1985). The lower PLW has been reported in heat shrinkable cryovac film in

mango fruits (Kumar and Nagpal, 1996), Nagpur mandarin (Sonkar and Ladaniya, 1998), guava

(Siddiqui and Gupta, 1997). Bhullar et al, (1984) observed that packaging film reduce the PLW

by retarding the rate of respiration and transpiration thus, increase the keeping quality of kinnow.

4.2 Firmness

The data on effect of different polymeric films on fruit firmness at 20±10C temperature

are presented in Table 3 and graphically shown in Figure 3 revealed that firmness of Patharnakh

pear fruits during storage was significantly affected by packing in different polymeric films. It is

evident from the data that the fruit firmness, in general followed a declining trend commensurate

with advancement in storage period. The fruits packed in Shrink film maintained the highest

average firmness (5.92 kg force) closely followed by Cling film (5.55 kg force) and also at all

stages of storage intervals. The control fruits registered the lowest mean firmness (4.64 kg force).

In case of Shrink film packed fruits the decline in firmness was gradual followed by Cling film,

whereas in case of control fruits, the decline was found to be abrupt and sharp. The firmness of

fruits in Shrink film was noticed to fall between 6.80 to 4.99 Kg force, whereas in Cling film it

was 6.51 to 4.31 Kg force from 7 to 28 days of storage interval. On the other hand, in case of

control, it ranged between 5.93 to 3.45 Kg force, thereby leading to excessive softening and

shriveling of fruits. The interaction between treatment and storage intervals was found to be

significant.

The data on effect of different polymeric films on firmness of pear fruits stored at

ambient temperature are presented in Table 4 and Figure 4. The fruits packed in Shrink film

maintained higher mean fruit firmness (5.73 kg force) during ambient storage and ranged

between 6.74 to 4.80 Kg force from 3 to 9 days as compared to control where mean fruit firmness

is 4.83 kg force and fruits experienced a faster loss of firmness during storage and ranged

between 5.95 to 3.75 Kg force. The pear fruits packed in Cling film also registered a lower and

steadier loss in firmness during storage (6.50 to 4.52 Kg force) during stipulated storage period of

9 days.

49

Table 3. Effect of different polymeric films on firmness (Kgf) in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28 Mean





Control 6.95 5.93 5.05 4.14 3.45 4.64

Mean 6.95 6.29 5.82 4.91 4.17

CD at 5% level

Treatment =0.03



50

Table 4. Effect of different polymeric films on firmness (Kgf) in pear cv. Patharnakh at ambient temperature

Treatments

Days after Storage

0 3 6 9 Mean





Control 7.00 5.95 4.78 3.75 4.83

Mean 7.00 6.29 5.15 4.17

CD at 5% level

Treatment =0.04



51

A perusal of the data shows that after 28 days of storage the fruit firmness values had

decreased from the initial value of 6.95 kg force to 4.99, 4.31, 4.15 and 3.95 kg force in the fruits

tray packed in Shrink, Cling, LDPE and HDPE films respectively, whereas the corresponding

value in case of control fruits was recorded to be 3.45 kg force. This reveals that polymeric film

packaging delays the softening process in pear fruits, with shrink films being better than the rest

in retaining the desirable fruits firmness. All the treatments performed significantly better

irrespective of wrapping with different polymeric film as compared to control. Softening of fruits

is caused either by breakdown of insoluble protopectins into soluble pectin or by hydrolysis of

starch (Mattoo et al 1975). The loss of pectic substances in the middle lamella of the cell wall is

perhaps the key steps in the ripening process that leads to the loss of cell wall integrity thus cause

loss of firmness and softening (Solomos and Laties, 1973).

The polythene wrapping of fruits resulted in higher fruit firmness, under both the storage

conditions, which might be due to high humidity maintained inside wrapped fruits thereby helped

in reducing the transpiration loss and respiration activity and thus retained more turgidity of the

cells. Further between Shrink and other films, shrink film showed increased efficiency in

maintaining better firmness which might be due to better retention of carbon dioxide gas and

restriction of external oxygen. Similar results were also observed in pomegranate fruits by Nanda

et al (2001); apple (Heaton et al, 1990); banana (Scott et al, 1971).

4.3 Spoilage (%)

The data on spoilage of pear fruits packed in different polymeric film and stored at 20±10C

temperature are presented in Table 5 and Figure 5. A perusal of data revealed that the rotting

percentage increased with the increase in storage period. The different packaging treatments

showed wide variation in spoilage during storage. The lowest mean cumulative spoilage (4.46%) in

terms of rotting was recorded in fruits packed in Shrink film, which was followed by Cling film

packed fruits (4.92%). The control fruits showed the highest mean spoilage of 8.51% and ranged

from 3.50% to 15.32% from 7 to 28 days of storage. However, the level of spoilage was

considerably low in Shrink film packed fruits (2.15% to 8.35%) and Cling film packed fruits

(2.45% to 9.06%) from 7 to 28 days of storage. The LDPE and HDPE film recorded intermediate

level of spoilage which ranged between 2.73% to 10.20% and 2.92% to 10.50% respectively. The

interaction between treatment and storage intervals was found to be significant.

The data on spoilage of pear fruits as influenced by different packaging films during

ambient storage are presented in Table 6 and Figure 6. The minimum average rotting (5.78%)

was noticed in control fruits. On the other hand, the maximum rotting was observed in HDPE

52

Table 5. Effect of different polymeric films on spoilage (%) in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28 Mean





Control 0.00 3.50 4.95 10.25 15.32 8.51

Mean 0.00 2.75 3.81 5.93 10.69

CD at 5% level

Treatment =0.04



53

Table 6. Effect of different polymeric films on spoilage (%) in pear cv. Patharnakh at ambient temperature


0 3 6 9 Mean





Control 0.00 3.00 6.35 8.00 5.78

Mean 0.00 5.20 8.97 14.42

CD at 5% level

Treatment =0.08



54

film (11.38%) followed by LDPE film packed fruits (11.18%). The Shrink and Cling film also

aggravated the rotting of fruits as compared to control fruits. The interaction between treatment

and storage was found significant. In control fruits, the spoilage ranged from 3.00% to 8.00%

from 3-9 days of storage whereas, in HDPE and LDPE packed fruits the level of spoilage

increased from 5.85% to 18.30% and 5.80% to 18.25%.

The beneficial and detrimental effects of packaging a fresh produce in polymeric films

have been evaluated for more than 25 years (Hardenburg, 1971 and Hardenburg, 1974). The

positive effect of film packaging is the maintenance of high relative humidity and reduction of

water loss of produce at optimum temperature and these conditions are responsible for lowering

the spoilage of fruits. However, the potential disadvantage of film wrapping at ambient

temperature is the possible water condensation and high temperature within the package,

which may encourage fungal growth and decay problem (Kader et al, 1989). In the present study,

it has been observed that under ambient conditions the level of spoilage in polymeric films was

maximum which may be due to accumulation of water vapours and high temperature within the

package which favours the fungal infection and this supports the findings of Chaplin et al (1982)

who reported that packaging of mango fruits in polyethylene bags followed by storage at ambient

temperature resulted in development of off flavour and decay. On the other hand, control fruits

(without film packaging) recorded lower spoilage which is obvious due to dry atmosphere around

the fruit surface.

However, under 20±10C temperature, it has been noticed that film wrapping has

favourable effect in reducing the spoilage of pear fruits which may be due to positive impact of

temperature in checking the growth of fungal infection. The present study confirm the results of

Yuen et al, (1993) who observed least rotting and best appearance of mango fruits packed in

perforated polythene bags or Cling or Shrink wraps followed by storage at optimum temperature .

4.4 Sensory quality

The data on sensory quality of pear fruits at a temperature of 20±10C are

presented in Table 7 and Figure 7. The mean maximum sensory score was shown by fruits packed

in Shrink film (7.87) followed by Cling film packed fruits (7.47), on the other hand, control fruits

registered the minimum sensory score (6.30). The sensory score of polymeric film packed fruits

increased gradually up to 21 days and thereafter declined, whereas, in control fruits, the sensory

score increased up to 14 days of storage and thereafter declined at faster pace. The sensory score

of fruits at this temperature condition revealed that the Shrink film packed fruits recorded a

55

highest score of 8.25 followed by Cling film (8.02) after 21 days of storage but the control fruits

showed maximum value (8.15) after 14 days of storage, thereafter, there was a faster decline in

the organoleptic score. The Shrink film and Cling film packed fruits were rated as very much

desirable to moderately desirable after 3 and 4 weeks of storage as compared to control which

were found acceptable up to 2 weeks of storage.

The data on sensory quality of pear fruits at ambient temperature are presented in Table 8

and Figure 8. The data revealed that the mean sensory score was significantly the highest (7.47)

in control fruits, which was followed by Shrink film packed fruits (6.82). The HDPE film packed

fruits recorded the lowest score (6.45).

The sensory quality gradually increased in all the treatments up to 6 days during storage.

However, the control fruits recorded the highest sensory score of 8.15 after 6 days of storage and

fruits were rated as very much desirable but thereafter a sudden decline in sensory quality was

noticed and fruits registered a score of 6.25 after 9 days of storage, and fruits rated as slightly

desirable. The sensory quality was the lowest in HDPE film packed fruits (7.25), followed by

LDPE film (7.30) and Shrink film (7.44) after 6 days of ambient storage and fruits were rated as

moderately desirable. Thereafter, a fast decline in organoleptic score was noticed in the fruits

packed in polyethylene films.

It has been reported that ethylene biosynthetic pathway functions better at 20-250C

(Yang, 1985) which may result in synthesis or formation of flavoring compounds. In present

studies it was noticed that pear fruits packed in Shrink or other films followed by storage at 20 0C

developed better sensory score as compared to unwrapped fruits, which could be possibly due to

congenial temperature and modification of gases in the polybags favouring development of

acceptable flavours. However, under ambient conditions the unwrapped fruits recorded better

sensory score than wrapped fruits which is obvious due to build up of adverse concentrations of

CO2 and very low concentration of O2 as a result of high temperature. These conditions are often

responsible for fermentation and development of off flavours (Geeson et al, 1991). Kader et al

(1989) envisaged that a film resulting in a favourable atmosphere at low temperature may result

in harmful atmosphere at higher temperature, thus make the quality of fruit acceptable in former

case and unacceptable in latter case.

56

Table 7. Effect of different polymeric films on sensory quality (0-9) in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28 Mean





Control 7.00 8.00 8.15 5.54 3.50 6.30

Mean 7.00 7.55 7.77 7.37 5.77

CD at 5% level

Treatment =0.03



57

Table 8: Effect of different polymeric films on sensory quality (0-9) in pear cv. Patharnakh at ambient temperature


0 3 6 9 Mean





Control 7.00 8.02 8.15 6.25 7.47

Mean 7.00 7.34 7.50 5.54

CD at 5% level

Treatment =0.04



58

Wrapping of mango fruits of cv. ‘Kensington pride’ in sealed polybags or in cling or shrink wraps

has been reported to maintain attractive appearance with eating quality up to 10 th day of storage

(Yuen et al, 1993). Sonkar and Ladaniya (1998) reported that Nagpur mandarin fruits packed in

stretch cling film had significantly higher flavour score and better acceptability and freshness

than non wrapped fruits after 60 days of storage. The apple fruits cv. Starcrimson showed

acceptable qualities for a period of 38 weeks while stored in shrink wrap packaging (Heaton et al,

1990).

4.5 Fruit colour

The data on effect of different polymeric films on the fruit colour of pear fruits at 20±10C

temperature are presented in Table 9. The fruit colour changed from green to yellow in all the

treatments with the advancement of storage period but in polymeric films the colour development

was slower and better than control. The Shrink film (Y5C) and Cling film (Y4A) showed better

yellow colour development and fruit brightness after 21 days of storage. The fruits packed in

LDPE and HDPE films also showed the same colour but the colour intensity was less than the

Shrink film and Cling film packed fruits. In control fruits, the change in colour was rapid initially

which showed yellow colour (GY1B) after 14 days of storage.

The data on effect of different polymeric films on fruit colour of pear fruits at ambient

temperature are presented in Table 10. Polymeric film packed fruits registered a faster

degradation of green colour and development of dull yellow colour than the control fruits. The

fruits packed in polymeric films attained light yellow colour after 6 days of storage and then

changed to dull yellow after 9 days. However, in control fruits, the colour development was

slower and fruits retained light yellow colour (Y4C) after 6 days of storage and remained light

yellow (Y5D) even after 9 days of storage.

In general, the loss in green colour of the fruits with the advancement of storage period

was due to the degradation of chlorophyll pigments and synthesis of carotenoids and

anthocyanins pigments (Wankier et al 1970). The increase in coloured pigment compounds

during storage ensured the ripening process of fruits.

Sweet orange cv. Mosambi wrapped in polythene bags showed better color

development as compared to non wrapped fruits (Tarkase et al, 1989). The increase in fruit

colour during storage and ripening have also been reported in Baby Gold-7 peaches by Dekazos

(1985) and also by Villanueva et al (1999) in Florda Gold peach fruits.

59

Table 9. Effect of different polymeric films on fruit colour in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28

Tray packing in LDPE YG154B YG154C GY1D GY1B Y5C

Tray packing in HDPE YG154B YG154C GY1D GY1B Y2A

Tray packing in Shrink film YG154B YG154D Y4C Y5C Y6B

Tray packing in Cling film YG154B YG154D Y3D Y4A Y3A

Control YG154B GY1D GY1B Y3A Y6A

60

Table 10. Effect of different polymeric films on fruit colour in pear cv. Patharnakh at ambient temperature


0 3 6 9

Tray packing in LDPE YG154B YG154C GY1D GY1B

Tray packing in HDPE YG154B YG154C GY1D GY1B

Tray packing in Shrink film YG154B YG154C Y2D Y2A

Tray packing in Cling film YG154B YG154D GY1D GY1B

Control YG154B YG154D Y4C Y5D

61

Miller et al (1986) concluded that mango fruit cv ‘Tommy Atkins’ wrapped in plastic

film developed less yellow colour and pulp at soft ripeness than non wrapped fruits held in

storage at 210C.

4.6 Total Soluble Solids

The data on effect of different polymeric films on TSS content of fruits stored at a

temperature of 20±10C are presented in Table 11 and Figure 9. The fruits packed in Shrink film

recorded maximum average TSS content (12.11%) followed by Cling film (11.87%). The control

fruits recorded the lowest average TSS content (11.23%). It was further observed that in Shrink

film packed fruits the TSS content increased slowly and steadily up to 21 days (13.25%) and

thereafter gradually declined after 28 days storage (10.95%). The similar trend was also noticed

in case of other polymeric films. On the other hand, control fruits recorded a faster rise in TSS

content up to 14 days (13.23%) and thereafter declined at a faster rate and recorded 9.15% TSS at

the end of 4 weeks of storage.

The data on TSS of pear fruits as influenced by various polymeric films at ambient

temperature are presented in Table 12 and figure 10. In control fruits, the TSS content

increased at a faster pace up to 6 days (13.35%) and thereafter a decline was noticed and

further maintained TSS of 11.05% after 9 days of storage. However, in case of polymeric

film packed fruit also similar trend was noticed but the level of TSS at every interval was

found to be lower as compared to control. The minimum level of mean TSS was observed in

case of HDPE films (10.86%) whereas it is maximum in control (12.32%).

The delayed increase in TSS over a longer period of time in film wrapped peach fruits

might be attributed to the sole reason that films retard ripening and senescence processes and

simultaneously reduced the conversion of starch into sugars. In general, the increase in TSS

during the storage period may be due to the numerous anabolic and catabolic processes taking

place in the fruits, preparing it for senescence. The reason for the increase in TSS could be

attributed to the water loss and hydrolysis of starch and other polysaccharides to soluble form

of sugar. Wills et al (1980) have also reported that starch gets hydrolyzed into mono and

disaccharides, which in turn may lead to an increase in TSS. Similar findings of increase in TSS of

peach fruits during storage have also been reported by Ochel et al (1993) and Salunkhe et al

(1968).

62

The increase in TSS and sugars during storage may possibly be due to breakdown of

complex organic metabolites into simple molecules or due to hydrolysis of starch into sugars

(Wani, 1997).

4.7 Total Sugars

The data on effect of different polymeric films on total sugars content of fruits

stored at a temperature of 20±10C are presented in Table 13 and Figure 11. The fruits

packed in Shrink film recorded maximum average total sugar content (8.70%) followed by

Cling film (8.46%). The control fruits recorded the lowest average total sugar content

(7.98%). It was further observed that in Shrink film packed fruits the total sugar content

increased slowly and steadily up to 21 days (9.68%) and thereafter gradually declined after

28 days storage (7.66%). The similar trend was also noticed in case of other polymeric

films. On the other hand, control fruits recorded a faster rise in total sugar content up to 14

days (9.52%) and thereafter declined at a faster rate and recorded 6.20% total sugar at the

end of 4 weeks of storage.

The data regarding effect of different polymeric films on the total sugars at ambient

temperature are presented in Table 14 and Figure 12. The total sugars in pear fruits increased

significantly during the storage period up to 6 days of storage and thereafter a decrease in total

sugar content was observed. Initially up to 3 days of storage, control fruits registered 9.04% of

total sugars and then increased slowly and steadily up to 6 days and recorded the highest value

(9.61%) and thereafter gradually declined, but even then the level of total sugars was higher in

control fruits. On the other hand, in the polymeric film wrapped fruits, the total sugar increased

up to 6 days and thereafter declined. Among different polymeric films, the HDPE films

maintained lowest level of total sugars (7.81%). The mean maximum total sugars (8.87%) were

found in control fruits followed by Shrink film packed fruits (8.57%) and Cling film packed

fruits(8.27%).

63

Table 11. Effect of different polymeric films on TSS (%) in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28 Mean





Control 11.00 12.30 13.23 10.23 9.15 11.23

Mean 11.00 11.72 12.17 12.39 10.18

CD at 5% level

Treatment =0.03



64

Table 12. Effect of different polymeric films on TSS (%) in pear cv. Patharnakh at ambient temperature


0 3 6 9 Mean





Control 11.00 12.55 13.35 11.05 12.32

Mean 11.00 11.79 12.52 10.37

CD at 5% level

Treatment =0.04



65

Table 13. Effect of different polymeric films on total sugars (%) in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28 Mean





Control 7.64 8.85 9.52 7.36 6.20 7.98

Mean 7.64 8.43 8.76 8.92 7.16

CD at 5% level

Treatment =0.03



66

Table14. Effect of different polymeric films on total sugars (%) in pear cv. Patharnakh at ambient temperature


0 3 6 9 Mean





Control 7.79 9.04 9.61 7.95 8.87

Mean 7.79 8.49 9.01 7.46

CD at 5% level

Treatment =0.04



67

4.8 Reducing Sugars

The data on effect of different polymeric films on reducing sugars of pears at 20±1 0C

temperature conditions are presented in Table 15 and Figure 13. The data showed that maximum

average reducing sugars was noticed in Shrink film packed fruits (6.52%) followed by Cling film

(6.34%), while control fruits recorded the minimum level of reducing sugars (5.98%). During

storage, initially the control fruits recorded the higher reducing sugars upto 2 weeks (7.14%) and

then declined. On the other hand, the reducing sugars in polymeric films wrapped fruits increased

upto 3 weeks and then declined gradually. However, the Shrink film packed fruits recorded

higher reducing sugars at every storage intervals (i.e. 6.45, 6.63, 7.27 and 5.74% from 7 to 28

days of storage) as compared to other polyethylene films.

The data regarding the effect of different polymeric films on reducing sugars at ambient

temperature are presented in Table 16 and Figure 14. The reducing sugars in pear fruits increased

significantly during the ambient storage period up to 6 days in all the treatments, thereafter a

decrease in reducing sugar content was observed. The maximum mean reducing sugars (6.65%)

were found in control fruits, followed by 6.43% in Shrink film packed fruits and 6.20% and

6.06% in Cling and LDPE film packed fruits respectively. The minimum mean reducing sugars

(5.86%) were recorded in HDPE film packed fruits.

4.9 Non-reducing Sugars

Data on non- reducing sugars of pear fruits when stored at 20±1 0C temperature

conditions are presented in Table 17 and Fig. 15. It was observed that in polyethylene film

packed fruits the non- reducing sugar content was lower than control after 14 days of storage

but later on the trend were different. Non-reducing sugars continued to increase in packed fruits

up to 21 days of storage. In Shrink film packed fruits, the highest non- reducing sugars (2.24%)

were recorded after 21 days of storage, thereafter declined gradually afterwards. In HDPE and

control fruits, the non- reducing sugar content was declined rapidly as compared to Shrink film

packed fruits.

The data on non- reducing sugars of pear as influenced by packaging treatments at

ambient storage are presented in Table 18 and Fig. 16. The data revealed that the non- reducing

sugars increased slowly and steadily up to 6 days of storage and thereafter declined gradually

irrespective of different treatments. The control fruits showed maximum non-reducing sugars

68

Table 15. Effect of different polymeric films on reducing sugars (%) in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28 Mean





Control 5.47 6.65 7.14 5.52 4.59 5.98

Mean 5.47 6.32 6.57 6.69 5.36

CD at 5% level

Treatment =0.03



69

Table 16. Effect of different polymeric films on reducing sugars (%) in pear cv. Patharnakh at ambient temperature


0 3 6 9 Mean





Control 5.89 6.78 7.20 5.96 6.65

Mean 5.89 6.37 6.75 5.59

CD at 5% level

Treatment =0.04



70

Table 17 .Effect of different polymeric films on non-reducing sugars (%) in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28 Mean





Control 1.69 2.02 2.21 1.71 1.49 1.86

Mean 1.69 1.96 2.04 2.07 1.67

CD at 5% level

Treatment =0.03



71

Table 18. Effect of different polymeric films on non-reducing sugars (%) in pear cv. Patharnakh at ambient temperature


0 3 6 9 Mean





Control 1.81 2.26 2.41 1.85 2.17

Mean 1.81 2.00 2.13 1.73

CD at 5% level

Treatment =0.04



72

(2.17%) followed by Shrink film packed fruits (1.99%) and Cling film packed fruits (1.92%). The

HDPE film packed fruits showed the minimum non- reducing sugars (1.81%) content.

The increase in sugars (total, reducing and non-reducing) during storage may possibly

due to breakdown of starch into sugars, as on complete hydrolysis of starch no further increase in

sugars occurs and subsequently a decline in these parameters is predictable as they along with

other organic acids are primary substrate for respiration (Wills et al 1980).

Singh et al (1967) reported that fruits of ‘Dusehri’ mango were in good condition after 14

days of storage when these were packed in perforated polythene in cold storage conditions. The

polythene packing treatment resulted in low TSS and sugars content over the control fruits during

early periods of storage but later on it increases than control.

The percentage of total sugar in mango juice was increased during storage and was

highest in case of treatments in which perforated polythene bags were used than in treatments in

which non perforated ones were used (Dhillon et al, 1977).

Total and reducing sugars increased with the advancement of storage interval in sand

pear as a result of different packing materials like high density polyethylene, low density

polyethylene, newspaper, tissue paper and paddy straw (Mohla et al, 2005).

4.10 Acidity

The data on effect of different polymeric films on acidity of pear fruits when stored at

20±10C temperature are presented in Table 19 and Figure 17. The data revealed that acidity of

pear fruits experienced a linear decline as the storage period advanced. It was observed that in all

the treatments, acidity was higher than the control. In Shrink film packed fruits, acidity was

significantly higher over the other treatments throughout the storage period. The Shrink film

packed fruits showed an average acidity of 0.30% and ranged from 0.35 to 0.19 per cent,

followed by Cling film packed fruits 0.33 to 0.17 per cent and in control fruits, it ranged from

0.30 to 0.12 per cent from 7 to 28 days of storage.

The data on effect of different polymeric films on titratable acidity of pear fruits

is shown in Table 20 and Figure 18. The loss of acidity during storage was gradual in Shrink film

and Cling film wrapped fruits whereas, it declines at a faster pace in case of control and HDPE

packed fruits. The highest mean acidity content (0.33%) was observed in Shrink film wrapped

fruits, followed by fruits wrapped in Cling film (0.31%), whereas, it was lowest in control

(0.20%).

73

Table 19. Effect of different polymeric films on acidity (%) in pear cv. Patharnakh at 20±10C temperature


0 7 14 21 28 Mean





Control 0.39 0.30 0.26 0.22 0.12 0.23

Mean 0.39 0.32 0.29 0.25 0.15

CD at 5% level

Treatment =0.01


Treatment x Storage interval =NS

74

Table 20. Effect of different polymeric films on Acidity (%) in pear cv. Patharnakh at ambient temperature


0 3 6 9 Mean





Control 0.45 0.27 0.19 0.14 0.20

Mean 0.45 0.33 0.28 0.21

CD at 5% level

Treatment =0.03


Treatment x Storage interval =NS

75

A significant difference in the acid content of the fruits was observed among the different storage

days. The interaction between treatment and storage was found to be non-significant.

The decrease in titratable acids during storage may be attributed to utilization of organic

acid in pyruvate decarboxylation reaction occuring during the ripening process of fruits (Rhodes

et al 1968 and Pool et al 1972).

In general, the acidity of the fruits decreased with increase in storage period. This was

possibly due to ripening and respiration activities inside the fruit tissue. However, when the fruits

were wrapped in perforated polythene, the lowering of acidity was delayed. This might be due to

the effect of polymeric films, which delayed the respiration and ripening process. Similar results

have been reported by Kalra et al (1986) in ‘Dusehri’ mango. Randhawa et al, 1982 reported that

acidity decreased during storage LeConte whereas it remained more or less same in Patharnakh

cultivar, Mann et al, (1976) also reported the same results for acidity. Venkatesha and Reddy

(1987) reported that acidity decreased in guava fruit with increase in storage period, this might be

due to the reason that polyethylene packaging arrested the ripening process by checking

transpiration and respiration thereby retained higher level of acidity. Bratley, (1939) reported that

the higher loss in titratable acidity during ambient storage which may be due to higher rate of

metabolism as compared to cold storage.

76

Chapter V

SUMMARY

The present investigations entitled, “Effect of different polymeric films on the storage life of

tray packed pear fruits” were conducted in the Department of Horticulture and Punjab

Horticultural Post-harvest Technology Centre, Punjab Agricultural University, Ludhiana

during the year 2007 and 2008. Fruits of cv. Patharnakh were harvested in the third week of

July at physiological mature stage for packaging and storage studies. The fruits of uniform

size, apparently free from diseases and bruises were sorted, washed with chlorine solution

(100 ppm). Thereafter, the fruits were divided into requisite lots and packed in trays and seal

wrapped with different polymeric films commercially available in the market i.e. Shrink film,

Cling film, Low Density Polyethylene film, High Density Polyethylene film. The control

fruits were kept un-packed. In the present study, two experiments were laid. In first

experiment the fruits were stored at 20±10C temperature and 90-95% RH (Supermarket

conditions) and were analyzed for various physico-chemical parameters at 7, 14, 21, 28 days

while in second experiment the fruits were stored at ambient temperature conditions (30-320C

and 75-80% RH) and were analyzed after 3, 6, 9 days interval after storage.

The results of present study are summarized below:

The physiological loss in weight during storage increased as the storage period

advanced, but it was found to be lowest in fruits packed in polymeric film and highest

in control during storage under both the temperature conditions. At 20±10C the

Shrink film and Cling film packed fruits recorded the mean PLW of 3.37 per cent and

3.72 per cent respectively. However, in case of control fruits the mean PLW was

found to be 6.05 per cent. Under ambient temperature, the Shrink film and Cling film

packed fruits showed mean PLW of 2.60 percent and 3.19 percent respectively as

compared to control fruits (4.53%).

Fruit firmness decreased with the prolongation of storage period. The fruits packed

with polymeric films maintained higher firmness than unwrapped fruits under both

the storage conditions.

Spoilage of fruits increased during storage. The polymeric film packed fruits

maintained a lower level of spoilage than unwrapped fruits under 20±10C temperature

conditions. In case of 20±10C, the Shrink film and Cling film maintained lower

77

spoilage (4.46 and 4.92 percent) as compared to other films and control (8.51

percent). However, in case of ambient storage, the control showed the lowest spoilage

(5.78 percent) as compared to polymeric film packed fruits.

At 20±10C, the increase in palatability rating was observed in Shrink film packed

fruits (8.25) upto 21 days of storage and then declined but in control fruits, initially

high palatability rating was observed upto 14 days (8.15) and then declined. At

ambient storage conditions the control fruits showed highest palatability rating after 6

days (8.15) of storage and thereafter declined. However, the film wrap fruits were

found poor in flavor and quality.

At 20±10C, the fruits packed in Shrink film and Cling film showed better distribution

and development of colour up to 21 days of storage than the control fruits where the

optimum colour development was registered after 14 days. Under ambient storage,

the polymeric film packed fruits showed poor colour development due to

unfavourably high temperature inside the film wrapped trays, while control fruits

showed better colour development and colour retention.

At 20±10C, the TSS, total sugars, reducing sugars and non- reducing sugars

increased significantly with the increase of storage period upto 21 days in Shrink

film (TSS-13.25%, total sugars-9.68%, reducing sugars-7.27%, non-reducing

sugars-2.24%) and decreased thereafter. However, these constituents increased

upto 14 days in control fruits and therafter a sharp decline was noticed. In case of

ambient storage, these constituents increase upto 6 days and were highest in

control fruits (TSS-13.35%, total sugars-9.61%, reducing sugars-7.20%, non-

reducing sugars-2.41%) and decreased thereafter.

Acidity in fruits decreased with the increase of storage period. Under both the

storage conditions film wrapping maintained higher acidity than control during

storage. However, among different polymeric films Shrink film maintained the

highest acidity.

From the present studies, it can be concluded that at 20±10C (Supermarket conditions) the

Patharnakh pear fruits packed in corrugated trays, over-wrapped with Shrink film or

Cling film can be stored for 21 days with minimum weight loss, spoilage, desirable

firmness and acceptable sensory quality.

78

At ambient temperature conditions, i.e. 30-320C and 75-80% RH, the un-wrapped

(control) fruits maintained better quality and can be stored for 6 days as compared to

polymeric films wrapped fruits. The polyethylene films interfere with overall quality of pear

fruit due to build up of high condensation and abnormal gas atmosphere in the package due to

high temperature.

The use of Shrink and Cling film seems to hold promise in extending the

marketability of pear fruits under supermarket retail conditions at 20±10C. On the other hand,

these films have adverse effect during retail marketing of pear fruit under ambient conditions.

79

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Figure 7: Effect of different polymeric films on sensory quality (0-9) in pear cv. Patharnakh at 20±10C temperature

Figure 8: Effect of different polymeric films on sensory quality (0-9) in pear cv. Patharnakh at ambient temperature

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Figure 1: Effect of different polymeric films on physiological loss in weight (%) in pear cv. Patharnakh at 20±10C temperature

Figure 2: Effect of different polymeric films on physiological loss in weight (%) in pear cv. Patharnakh at ambient temperature

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Figure5. Effect of different polymeric films on spoilage (%) in pear cv. Patharnakh at 20±10C temperature

Figure 6. Effect of different polymeric films on spoilage (%) in pear cv. Patharnakh at ambient temperature

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Figure 9. Effect of different polymeric films on TSS (%) in pear cv. Patharnakh at 20±10C temperature

Figure 10. Effect of different polymeric films on total soluble solids in pear cv. Patharnakh at ambient temperature

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Figure 11. Effect of different polymeric films on total sugars (%) in pear cv. Patharnakh at 20±10C temperature

Figure 12. Effect of different polymeric films on total sugars (%) in pear cv. Patharnakh at ambient temperature

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Figure 13. Effect of different polymeric films on reducing sugars (%) in pear cv. Patharnakh at 20±10C temperature

Figure 14. Effect of different polymeric films on reducing sugars (%) in pear cv. Patharnakh at ambient temperature

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Figure 15. Effect of different polymeric films on non-reducing sugars (%) in pear cv. Patharnakh at 20±10C temperature

Figure 16. Effect of different polymeric films on non-reducing sugars (%) in pear cv. Patharnakh at ambient temperature

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Figure 3. Effect of different polymeric films on firmness (Kgf) in pear cv. Patharnakh at 20±10C temperature

Figure 4. Effect of different polymeric films on firmness (Kgf) in pear cv. Patharnakh at ambient temperature

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Figure 17. Effect of different polymeric films on acidity (%) in pear cv. Patharnakh at 20±10C temperature

Figure 18. Effect of different polymeric films on Acidity (%) in pear cv. Patharnakh at ambient temperature

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effect of different polymeric films on the storage life of tray packed pear fruits

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