at SciVerse ScienceDirect

LWT - Food Science and Technology 52 (2013) 102e109

Contents lists available

LWT - Food Science and Technology

journal homepage: www.elsevier .com/locate/ lwt

The shelf life extension of fresh strawberries using an oxygen absorberin the biobased package

Mehmet Seckin Aday*, Cengiz Caner*

Department of Food Engineering, Canakkale Onsekiz Mart University, 17020 Canakkale, Turkey

a r t i c l e i n f o

Article history:Received 29 January 2012Received in revised form31 May 2012Accepted 8 June 2012

Keywords:StrawberryActive packagingOxygen absorberShelf life

* Corresponding authors. Tel.: þ90 286 2180018x21E-mail addresses: mseckinaday@comu.edu.tr (M.S

(C. Caner).

0023-6438/$ e see front matter � 2012 Elsevier Ltd.http://dx.doi.org/10.1016/j.lwt.2012.06.006

a b s t r a c t

Oxygen absorbers are one of the most widely used materials in active packaging technology to extendshelf life of fruits. In this paper, effectiveness of two types of oxygen absorbers on quality of freshstrawberries is reported. Gas composition inside package, pH, total soluble solids, electrical conductivity,color, texture, decay incidence, sensory and FT-NIR analyses were performed during 4 weeks storage at4 �C. After two weeks of storage, ATCO-100 (100 mL scavenging capacity) and ATCO-210 (210 mLscavenging capacity) saturated and in the third week of storage, O2 concentration increased to 6 kPa dueto the O2 transmitted from outside to the inside package. Loss of total soluble solid, pH and electricalleakage were higher in the control strawberries than packaged with O2 absorbers. Strawberries packagedwith oxygen absorbers had significantly higher L* and a* values as compared to control fruits. Absorbershad significant effect on maintaining firmness and mold reduction of strawberry. According to panelists,strawberries exposed to absorbers showed better scores than control for all attributes. FT-NIR spectragave insightful information about water and carbohydrate content of strawberry. Results of this studyconfirm that the oxygen absorbers can be used to extend shelf life of fresh strawberry.

� 2012 Elsevier Ltd. All rights reserved.

1. Introduction

Strawberry is highly perishable fruit and mostly consumed asfresh. However, strawberry deteriorates quickly due to physicalabuse, water loss and microbiological decay (Fan et al., 2009).Therefore appropriate post harvest treatments should be used toprevent the serious economic losses.

Active packaging is one of them to preserve quality and plays anactive role other than acting as an inert barrier. The package, product,and environment interact in a positive way to improve the productquality in active packaging (Miltz & Perry, 2005). Active packaging isused for various purposes, such as oxygen and carbon dioxide scav-engers, moisture regulators, antimicrobials and controlling therelease or absorption mechanism of flavors (Álvarez, 2000).

Oxygen scavengers are well known and most commonly usedtechnology nowadays in active packaging. Oxygen scavengers slowdown food deterioration by preventing the growth of microor-ganisms and slowing oxidation reactions. Therefore, oxygen scav-engers might have better utilization on oxygen sensitive fruit andvegetables (Charles, Sanchez, & Gontard, 2006).

72; fax: þ90 2862180541.. Aday), ccaner@comu.edu.tr

All rights reserved.

Several studies have been published explaining the effect ofoxygen absorber on the quality of fruit and vegetables. Charles,Guillaume, and Gontard (2008) showed that oxygen scavengerreduces the transient period to 50% which led to control ofbrowning in fresh endives. Tarr and Clingeleffer (2005) demon-strated that oxygen absorber in the package of dried wine fruitminimized the color change. According to Charles, Sanchez, andGontard (2003) oxygen absorbers slow down the accumulation ofCO2 and reduce the transient period of tomato during storage.

In addition to our knowledge, no research has been published onobserving the effect of oxygen scavengers on the quality of freshstrawberries. Thus, the goal of this research was to evaluate andcompare the effect of two different oxygen scavengers on quality ofair packaged strawberry in terms of chemical, physical and senso-rial characteristics during storage.

2. Material and methods

2.1. Materials

Strawberry (Fragaria � ananassa) cv. Camarosa, was harvestedfrom the local farm in Kepez, Turkey. Only fruits having uniformripening stage, size, color, shape and without physical injuries wereselected. Polylactic acid (PLA) trays supplied by Huhtamaki (Istan-bul, Turkey) were used as packaging material. Strawberries (200 g)

M.S. Aday, C. Caner / LWT - Food Science and Technology 52 (2013) 102e109 103

were put in the trays (750 mL) and stored at 4 �C. All the trays wereclosed under atmospheric condition. Transmission rates of trayswere 620 cm3 mil/m2 day atm, 2800 cm3 mil/m2 day atm, and340 g mil/m2 day, for O2, CO2 and H2O respectively.

2.2. Oxygen (O2) absorber

Two different types of commercial oxygen scavenger sachets(ATCO-100 and ATCO-210) were supplied by Standa Industries(Caen, France). ATCO-100 and ATCO-210 sachets have an oxygenabsorbing capacity of 100 mL and 210 mL, respectively.

2.3. Treatments

Strawberries were placed in three different types of packages aslisted below and they were stored for four weeks.

1) Control: Strawberries packaged in atmosphere condition(21 kPa O2 þ 0.03 kPa CO2).

2) ATCO-100: Strawberries packaged in atmosphere condition(21 kPa O2 þ 0.03 kPa CO2) þ ATCO-100 oxygen absorber.

3) ATCO-210: Strawberries packaged in atmosphere condition(21 kPa O2 þ 0.03 kPa CO2) þ ATCO-210 oxygen absorber.

Oxygen scavengers were placed at the side walls of packagesbefore sealing. For each treatment, twenty packages of strawberrieswere prepared and four packages were used at each week for thesame treatment.

2.4. Gas composition inside the packages

Gas concentration of headspace was monitored by an Oxybabygas analyzer (HTK, Hamburg, Germany) before opening packages.The gas analyzer’s needle was inserted through impermeablerubber seal which attached outside of the package film. The resultswere expressed as O2 kPa and CO2 kPa. Calibration was done byusing air (Aday & Caner, 2011).

2.5. pH measurement

Before taking the measurements, stem and calyx of the straw-berry were discarded and fruits were homogenized with blender.From each package eight fruits were homogenized. The strawberryjuice was filtered through a cheese cloth and then pH value ofstrawberry juice was determined with a pHmeter (Sartorius PP-50,Goettingen, Germany) (Aday, Caner, & Rahvalı, 2011).

2.6. Total soluble solid

Strawberries were homogenized with blender and filtered witha cheese cloth. Total soluble solid content and pH of strawberrywere measured on same fruit juice using a Atago Pal-1 pocketrefractometer (Atago Co. Ltd., Tokyo, Japan) and expressed aspercentage (%) at 20 �C (Caner & Aday, 2009).

2.7. Electrical conductivity

For electrical conductivity, 5 g of strawberry was incubated in50 mL deionized water. Then electrical conductivity of this solutionwas measured at 1 min (C1) and 60 min (C60) with a PP 50 Sartorius(Sartorius PP-50, Goettingen, Germany). After this solution incu-bated for 25 min at 121 �C (C121), total conductivity was measured(Fan & Sokorai, 2005). Electrical leakage (E) was calculated from thefollowing equation;

E ¼ ðC60 � C1Þ=C121 � 100 (1)

2.8. Color

Color value of strawberry (10 strawberries per treatment) wasmeasured at the equatorial region and was recorded with a MinoltaChromaMeter CR-400 (Minolta, Japan). CIELAB color system (L*, a*)was used to determine the differences between samples. Colormeter was calibrated using the standard white plate beforemeasurements (Caner & Aday, 2009).

2.9. Texture profile analyses (TPA)

TA.XT-PLUS Texture Analyzer (Stable Micro Systems Ltd., UK)was used to measure TPA parameters. Texture analyzer wasequipped with a 30 kg load cell and the 10 mm diameter cylinderplunger SMS-P/10 CYL Delrin probe. Strawberries were laid downand compressed at a pre test speed of 5 mm/s, test speed of 1 mm/sand post test speed of 8 mm/s for texture profile analyses.Compression distance was 4 mm and between two cycles, restperiod was 5 s. From the resulting forceetime curve (Fig. 1),parameters [firmness (maximum peak force for first compression),springiness (Length 2/Length 1), cohesiveness ([Area 4 þ Area 5]/[Area 1 þ Area 2]), adhesiveness (Area 3), gumminess (maximumpeak force for first compression) � ([Area 4 þ Area 5]/[Area1 þ Area 2]), chewiness (maximum peak force for firstcompression � [Area 4 þ Area 5] � [Length 2/Length 1]), andresilience (Area 2/Area 1) were measured with Texture ExponentSoftware. For each treatment, 10 strawberries were analyzed atroom temperature (Caner, Aday, & Demir, 2008).

2.10. Decay incidence

Decay incidence was visually evaluated on day 21th and day28th. Numbers of fruits with visual mold lesions on surface wererecorded. Fruit with no signs of decay were recorded as healthy.Decay incidence was expressed as (Aday et al., 2011);

ðInfected strawberries in packageÞ� 100=ðtotal strawberries in packageÞ (2)

2.11. Sensory evaluation

Quality attributes (appearance, color, flavor, texture, generalacceptability) of strawberries were evaluated using a nine pointhedonic scale where 9 indicated that excellent, freshly; 7 ¼ verygood; 5 ¼ good, limit of marketability; 3 ¼ fair, limit of usability;and 1 ¼ poor, unusable (Aday & Caner, 2011). Treatments werepresented in polystyrene trays which were coded with three digitnumbers and served to untrained panel of nine judges. Panelistsused water to cleanse their mouth from residual taste between thesamples.

2.12. FT-NIR analysis

The near infrared spectral specifications were measured withBruker Multi-purpose Analyser (MPA) FT-NIR spectrometer (BrukerOptic, Gmbh, Ettlingen, Germany). The FT-NIR spectrometerincludes TE-InGaAs detectors for reflectance and RT-IngaAs detec-tors for transmittance. The reflectance measurements were per-formed with fiber optic probe (type IN 261) with 32 scans andbetween 780 and 2500 nmwavelengths. The probe angle set to 900

angles to take reflectance spectrums of whole strawberries. The

A

Storage Time (Weeks)

0 1 2 3 4

O2 C

once

ntra

tion

(kPa

)

0123456789

1011121314151617181920212223

B

Storage Time (Weeks)

0 1 2 3 4

CO

2 Con

cent

ratio

n (k

Pa)

02468

1012141618202224262830323436384042

Fig. 2. Effect of different absorbers [(C) control (without absorber) (B) ATCO-100(absorption capacity of 100 mL O2) (;)ATCO-210 (absorption capacity of 210 mL O2)in headspace gas composition [A) O2 and B) CO2] of strawberry during storage. Verticalbars denote standard deviation of three replicates.

Fig. 1. Forceetime curve of strawberries obtained in texture profile analysis mode.

M.S. Aday, C. Caner / LWT - Food Science and Technology 52 (2013) 102e109104

transmittance measurements were scanned 64 times and coveredbetween 800 and 1725 nm wavelengths. For the transmittancemeasurements; whole strawberry was placed horizontally to thetransmittance area. OPUS software (Bruker Optik, GmbH, Ettlingen,Germany) was used as instrument control (Aday & Caner, 2010;Aday et al., 2011).

2.13. Statistical analysis

The results were subjected to analysis of variance (ANOVA) atp < 0.05 to determine which factors (oxygen absorbers and storagetime) and interaction between factors affected the quality proper-ties of strawberry. The study was repeated three times and analyseswere run in triplicate for each replicate.

When interactions (treatment � storage time) were found notsignificant, overall value was used to compare the means of factors(treatment or storage time). To determine significant differencesbetween treatments, Tukey post-hoc comparison test was applied(p < 0.05). Each value is expressed as mean � standard deviation.SAS 9.2 was used for statistical analyses.

3. Results

3.1. O2 and CO2 headspace concentration

The changes in concentration of O2 and CO2 over storage periodcan be used to indirectly evaluate the respiration rates of fresh fruitand vegetables (Fonseca, Oliveira, & Brecht, 2002). From the data inFig. 2a, it is clear that O2 concentration inside the packagedecreased quickly for ATCO-210 and ATCO-100 treatments as ex-pected. After two weeks of storage, oxygen absorbers were satu-rated and in the third week of storage, O2 concentration increasedto 6 kPa. It can be concluded that O2 transmitted fromoutside to theinside package through packaging film. At the end of the thirdweek, O2 concentration inside the control package decreased to0.1 kPa due to high mold activity. In Fig. 2b, there is a clear trend ofincreasing CO2 concentration with storage time. After first week ofstorage, CO2 levels inside control package increased significantlywhen compared to packages with O2 absorbers until the end of thestorage. This can be explained by the fact that molds in control

Table 1pH analysis of control and treated strawberry during storage.

Treatments Storage time (week)/pH value

0 1 2 3 4 Overall

Control 3.33 � 0.09 3.62 � 0.02 3.75 � 0.03 3.82 � 0.03 3.89 � 0.03 3.62 � 0.23aATCO-100 3.33 � 0.09 3.50 � 0.04 3.65 � 0.01 3.69 � 0.01 3.76 � 0.02 3.54 � 0.18bATCO-210 3.33 � 0.09 3.46 � 0.05 3.65 � 0.03 3.65 � 0.03 3.82 � 0.02 3.55 � 0.20bOverall 3.33 � 0.09A 3.53 � 0.08B 3.68 � 0.05C 3.68 � 0.05CD 3.82 � 0.06D

Control (without absorber), ATCO-100 (Absorption capacity of 100mL O2), ATCO-210 (Absorption capacity of 210mL O2). Interaction (treatment� storage time) was found notsignificant (p > 0.05). Main effect of treatments and storage times were statistically significant (p � 0.05).AeC Mean in the same row with different letters are significantly different (p � 0.05).aec Mean in the same column with different letters are significantly different (p � 0.05).

M.S. Aday, C. Caner / LWT - Food Science and Technology 52 (2013) 102e109 105

packages depleted the oxygen with respiration and they accumu-lated high levels of carbon dioxide inside packages. The furtherincrease in carbon dioxide levels stimulated the fermentativerespiration of glucose to carbon dioxide (Joles, Cameron, Shirazi,Petracek, & Beaudry, 1994). These results demonstrate thatoxygen absorbers inside the packages were effective to slow downrespiration rate and preventing the breakdown of organicsubstrates (carbohydrates, lipids, organic acids) into more simplemolecules (Fonseca et al., 2002).

3.2. pH

Table 1 compares the results obtained from the analysis of pH. Atthe end of the storage, pH values of strawberries in control pack-ages reached to 3.89. On the same day, pH values of fruits packagedwith ATCO-100 and ATCO-210 were 3.76 and 3.82, respectively. Apossible explanation for this might be that high CO2 levels resultedwith higher pH values for control packages (Almenar et al., 2007).In addition, rapid decrease at acid content might be the utilizationof organic acids and their conversion to sugars during respiration(Martinez-Ferrer, Harper, Perez-Muroz, & Chaparro, 2002).

3.3. Total soluble solids (TSS)

Total soluble solids is an important parameter to determine thefruit quality (Aday et al., 2011). Table 2 shows the result of exper-imental data on TSS values. The values of strawberries decreasedslightly during four weeks of storage. At the end of the storage, TSScontent of control strawberries decreased to 7.68%, while the TSSvalues of strawberries exposed to O2 sachets were 8.17% and 7.99%.The decrease in TSS values was higher in the control strawberries.This observed diminishment can be explained by the hydrolysis ofsucrose in order to maintain physiological activity and respiration(Aday et al., 2011; Li, Zhang, & Wang, 2008).

3.4. Electrical conductivity

Electrical conductivity can be used effectively to evaluate themembrane damage (Feng, Yang, & Li, 2005). Fig. 3 shows electrical

Table 2Total soluble solid content of control and treated strawberry during storage.

Treatments Storage time (week)/total soluble solid (%)

0 1 2

Control 10.55 � 0.07 8.99 � 0.10 8.71 � 0.ATCO-100 10.55 � 0.07 9.73 � 0.05 8.96 � 0.ATCO-210 10.55 � 0.07 9.50 � 0.14 9.39 � 0.Overall 10.55 � 0.07A 9.41 � 0.35B 8.98 � 0.

Control (without absorber), ATCO-100 (Absorption capacity of 100mL O2), ATCO-210 (Abssignificant (p > 0.05). Main effect of treatments and storage times were statistically signAeC Mean in the same row with different letters are significantly different (p � 0.05).aec Mean in the same column with different letters are significantly different (p � 0.05).

conductivity of strawberry in response to O2 absorbers. Controlstrawberries showed the highest electrical conductivity valueduring the entire storage period. It can therefore be assumed thathigh concentration of CO2 increased the permeability of strawberrytissue and induced cell membrane damage (Chen & Paull, 2001).

3.5. Color

Color is a critical objective parameter which can be used asa quality index to describe the color degradation (Rodrigo, van Loey,& Hendrickx, 2007). The results obtained from the analysis of colorvalues (L* and a*) are presented in Table 3. Strawberries turned tobrown during the storage. Reduction of a* values (less redness) ofcontrol strawberries was significant as compared to O2 absorbertreatments. Color deterioration was due to loss of anthocyaninpigments or formation of Maillard products (Aguiló-Aguayo, Oms-Oliu, Soliva-Fortuny, & Martín-Belloso, 2009). Also this result maybe explained with that increase in respiration rate and enzymaticprocess lead to loss of quality (Del-Valle, Hernandez-Munoz,Guarda, & Galotto, 2005).

The L* parameter indicates the darkening level of fruits(Hernandez-Munoz, Almenar, Del Valle, Velez, & Gavara, 2008). Thefruits exposed to O2 absorbers had significantly higher L* values ascompared to control during the entire storage period. L* values ofstrawberries exposed to ATCO-100 absorbers were slightly higherthan the strawberries packaged with ATCO-210 absorbers, but thedifference was not significant.

3.6. Texture profile analysis (TPA)

Texture is an important attribute which related with quality andshelf life of fruit (Ali, Chin, Marimuthu, & Lazan, 2004). The termfirmness can be defined as the force necessary to attain a givendeformation (de Huidobro, Miguel, Blazquez, & Onega, 2005).Fig. 4a presents the changes in firmness over four weeks of storage.At the end of the storage, the highest firmness value observed instrawberries exposed to ATCO-100 absorbers with the value of402 g. However, on the same day, firmness values of strawberriespackaged with ATCO-210 and without absorbers (control) were

3 4 Overall

11 7.72 � 0.05 7.68 � 0.19 8.71 � 1.10a09 8.35 � 0.84 8.17 � 0.14 9.27 � 0.98b73 8.22 � 0.84 7.99 � 0.06 9.14 � 1.05b57B 8.10 � 0.59C 7.95 � 0.24C

orption capacity of 210mL O2). Interaction (treatment� storage time) was found notificant (p � 0.05).

A A AA

BB

A

B B

A

BB

A

B B

Storage Time (Weeks)

0 1 2 3 4

Elec

trica

l Con

duct

ivity

(µS/

cm)

0,20

0,25

0,30

0,35

0,40

Fig. 3. Electrical conductivity changes of strawberry during storage. [( ) control(without absorber), ( ) ATCO-100 (absorption capacity of 100 mL O2), ( ) ATCO-210 (absorption capacity of 210 mL O2)]. Vertical bars denote standard deviation ofthree replicates.

M.S. Aday, C. Caner / LWT - Food Science and Technology 52 (2013) 102e109106

353 g and 228 g, respectively. A possible explanation for this mightbe that O2 absorbers reduced the respiration rate and this resultedin prevention of the cell rupture, water loss and starch to sugarconversion (Moreno et al., 2012; Pitt, 1992).

In the literature, the term adhesiveness is generally known ascombination of adhesive and cohesive force (Spaziani, del Torre, &Stecchini, 2009). Fig. 4b shows the changes in adhesiveness valueof strawberries during the storage. Control strawberries hada high adhesion throughout the storage. It seems possible thathigh CO2 level (indicator of high respiration rate) inside control

Table 3Color “L*” and “a*” changes of control and treated strawberry during storage.

Treatments 0 1 2

Storage time (week)/L* valueControl 34.83 � 1.94 30.98 � 0.82 29.96 � 1ATCO-100 34.83 � 1.94 33.63 � 1.94 33.23 � 0ATCO-210 34.83 � 1.94 33.33 � 1.79 33.06 � 1Overall 34.83 � 1.94A 32.65 � 0.17AB 32.08 � 1Storage time (week)/a* valueCONTROL 36.07 � 1.49 32.31 � 0.33 28.83 � 0ATCO-100 36.07 � 1.49 34.85 � 1.48 31.83 � 1ATCO-210 36.07 � 1.49 34.55 � 1.97 31.86 � 0OVERALL 36.07 � 1.49A 33.90 � 1.66A 30.84 � 1

Control (without absorber), ATCO-100 (Absorption capacity of 100mL O2), ATCO-210 (Abssignificant (p > 0.05). Main effect of treatments and storage times were statistically signAeC Mean in the same row with different letters are significantly different (p � 0.05).aeb Mean in the same column with different letters are significantly different (p � 0.05)

packages triggered the solubilization of the cell wall constituentsand affected the adhesiveness values (Del-Valle et al., 2005; Pitt,1992).

Use of the term springiness is related with elastical capacity offood which goes back to undeformed structure after force isremoved (de Huidobro et al., 2005). We observed from Fig. 4c that,springiness values decreased during the storage for all groups. Forstrawberries exposed to O2 absorbers, springiness decreasedslightly (from 0.63 to 0.57 and 0.55 for ATCO-100 and ATCO-210,respectively) whereas springiness values of control decreasedsharply (from 0.63 to 0.51). This result may be explained by the factthat O2 absorbers maintained the cell to cell adhesion and cell wallstability (Hernandez-Munoz et al., 2008).

The term cohesiveness can be explained with difficulty degreein breaking down and strength of the internal bonds of food(Spaziani et al., 2009; Yang et al., 2007). The Fig. 4d shows thatthere has been a sharp drop in the value of cohesiveness for controlduring the storage. Observed decrease in cohesiveness value ofcontrol strawberries could be attributed to cell to cell debondingand cell breakage (Harker, Elgar, Watkins, Jackson, & Hallett, 2000).

Gumminess refers to the required force to breakdown food forswallowing. As shown in Fig. 4e, there is a clear trend of decreasinggumminess value throughout the storage. Gumminess value ofstrawberry was not affected by the absorption capacity ofabsorbers. However significant differences were observed betweencontrol and O2 absorbers. These differences may be related toprevention the loss in cell turgidity pressure and loss of extracel-lular and vascular air (Del-Valle et al., 2005) by O2 absorbers whichdecreased the respiration.

Chewiness is defined as the required energy tomasticate samplefor swallowing (Huang, Kennedy, Li, Xu, & Xie, 2007). Fig. 4fprovides the results obtained from the chewiness analysis of allgroups. After first week, chewiness values of strawberries exposedto ATCO-210 and control decreased significantly until end of thestorage. During the storage, strawberries packaged with ATCO-100had significantly higher chewiness value than ATCO-210 andcontrol. Lower chewiness values of control may have been due todepolymerization of pectin degradation of middle lamella (Vicente,Ortugno, Powell, Greve, & Labavitch, 2007).

Resilience described as the redeformation capacity of fruit afterforce removed. Fig. 4g presents the experimental data on resiliencevalues over four weeks of storage. Resilience values were similarregardless of different O2 absorber capacities during the storage. Interms of resilience, significant difference found between O2absorbers and control. A possible explanation for this might be thatO2 absorbers retarded the respiration and slowed down theenzymes which uses cell wall polysaccharides as a substrate(Toivonen & Brummell, 2008).

3 4 Overall

.22 28.97 � 1.19 28.68 � 0.14 30.68 � 2.51a

.03 32.75 � 0.31 32.09 � 2.11 33.31 � 1.51b

.72 31.85 � 0.13 31.52 � 0.26 32.92 � 1.63b

.90B 31.19 � 1.85B 30.77 � 1.89B

.09 26.02 � 1.68 25.68 � 2.12 29.78 � 4.28a

.78 28.52 � 0.09 27.23 � 1.99 31.70 � 3.79b

.38 28.07 � 0.52 27.07 � 0.09 31.52 � 3.79b

.76B 27.54 � 1.43C 26.66 � 1.51C

orption capacity of 210mL O2). Interaction (treatment� storage time) was found notificant (p � 0.05).

.

M.S. Aday, C. Caner / LWT - Food Science and Technology 52 (2013) 102e109 107

3.7. Decay incidence

Strawberry has a short life due to mold growth caused byBotrytis cinerea which is responsible for economic losses (Zhanget al., 2007). The packages with O2 absorbers had significanteffect on mold reduction on day 21 and 28. Control showed thehighest spoilage with a percentage of 66% and 72% at day 21 and 28,respectively. In the third week and at the end of the storage,strawberries packaged with ATCO-100 absorbers were infected by

A

C

E

Storage Time (Weeks)

Firm

ness

(g)

200300400500600700800900

1000110012001300

Storage Time (Weeks)0 1 2 3 4 5

0 1 2 3 4 5

0 1 2 3 4 5

0 1 2 3 4 5

Sprin

gnes

s (D

imen

sion

less

)

0,460,470,480,490,500,510,520,530,540,550,560,570,580,590,600,610,620,630,640,650,66

Storage Time (Weeks)

Gum

min

ess

(g)

100

150

200

250

300

350

400

450

500

550

G

Storage Time (Weeks)

Res

ilienc

e (D

imen

sion

less

)

0,160,170,180,190,200,210,220,230,240,250,260,27

Fig. 4. Texture parameters [a) firmness, b) adhesiveness, c) springness, d) cohesiveness, econtrol (without absorber) (B) ATCO-100 (absorption capacity of 100 mL O2) (;) ATCO-21replicates.

gray molds with rate of 11% and 15%, while the decay incidence ofATCO 210 was 14% and 20%, respectively. There were no significantdifference between ATCO-100 and ATCO-210. The results revealedthat, O2 absorbers were effective to inactivate the molds.

3.8. Sensory analysis

According to panelists, strawberries exposed to O2 absorbersshowed better scores than control for all attributes. Control group

B

D

F

Storage Time (Weeks)Ad

hesi

vene

ss (g

.s)

2,002,252,502,753,003,253,503,754,004,254,504,755,005,255,505,756,00

0 1 2 3 4 5

0 1 2 3 4 5

0 1 2 3 4 5

Storage Time (Weeks)

Coh

esiv

enes

s (D

imen

sion

less

)

0,46

0,47

0,48

0,49

0,50

0,51

0,52

0,53

0,54

0,55

Storage Time (Weeks)

Che

win

ess

(g)

75100125150175200225250275300325

) gumminess, f) chewiness, g) resilience] changes of strawberry during storage. [(C)0 (absorption capacity of 210 mL O2)]. Vertical bars denote standard deviation of three

Table 4Sensory characteristics of control and treated strawberries.

Treatments Sensory evaluation

Global appearance Color Flavor Texture General acceptability

Control 4.66 � 1.32a 4.81 � 1.09a 5.27 � 1.07a 6.00 � 1.28a 5.50 � 1.15aATCO-100 6.11 � 0.47b 6.96 � 0.78b 6.61 � 0.69b 7.11 � 0.96b 7.50 � 0.51bATCO-210 6.58 � 0.50b 6.47 � 0.51b 6.94 � 0.42b 7.47 � 0.62b 8.00 � 0.35b

Control (without absorber), ATCO-100 (Absorption capacity of 100 mL O2), ATCO-210 (Absorption capacity of 210 mL O2).aeb Mean in the same column with different letters are significantly different (p � 0.05).

M.S. Aday, C. Caner / LWT - Food Science and Technology 52 (2013) 102e109108

had the values with the range of marketability (around 5) exceptcolor and global appearance, but strawberries exposed to O2absorbers showed higher preference with the values around 7 forall parameters (Table 4). No significant differences were detected bypanelists between ATCO-100 and ATCO-210 for sensorial attributes.Our sensorial analysis scores were in accordance with instrumentalcolor and texture values. Control strawberries with low color (a*and L*) and firmness values received low scores by panelists forglobal appearance, color and texture attributes when comparedwith strawberries exposed to O2 absorbers.

Fig. 5. Average relative absorbance spectra of strawberry obtained in reflectancemodes at the beginning and at the end of storage. [( ) day 0-control (withoutabsorber), ( ) week 4-control, ( ) week 4-ATCO-100 (absorption capacity of100 mL O2), ( ) week 4-ATCO-210 (absorption capacity of 210 mL O2)].

Fig. 6. Average relative absorbance spectra of strawberries obtained in transmissionmodes at the beginning and at the end of storage. [( ) day 0-control (withoutabsorber), ( ) week 4-Control, ( ) week 4-ATCO-100 (absorption capacity of100 mL O2), ( ) week 4-ATCO-210 (absorption capacity of 210 mL O2)].

3.9. FT-NIR evaluation

The Fourier Transform near-infrared spectroscopy is nonde-structive method and can be used to identify the overtones andfunctional groups (eOH, eCH, eNH, eSH, etc.) in foods rapidly(Luck, Buge, Plettenberg, & Hoffmann, 2010). Spectra’s of the controland treated strawberries on week zero and week four are shown inFigs. 5 and 6. Main absorption bands for water can be determined at760, 970, 1170 and 1450 nm (Nicolai et al., 2007). From the data inFig. 5, Control 0 had the highest absorbance band at 1450 nm relatedwith water content as expected. After four weeks of storage, ex-pected decreasewas observed for both control and treated groups at1450 nm. But control showed the biggest diminishment comparedwith treated groups. This observed decline, might be associatedwith water loss. O2 absorbers slowed down the respiration rate andlowered the metabolic activity and prevented water loss by the cellbreakdown (Del-Valle et al., 2005). Absorption band at 980 nmwasrelated to carbohydrate bands (Bobelyn et al., 2010). As detailed inFig. 6, the peak height at 980 nm was highest on week 0, as pre-dicted. At the end of the storage, control had the lowest absorptionband at 980 nmwhen compared with treated groups. A reasonableexplanation for this decrease may be that cell wall structure ofcontrol strawberry degraded by pectin solubilization, pectincleavage due to high rate of carbohydrate metabolism and fungaldecay (Vicente, Costa, Martinez, Chaves, & Civello, 2005). Anotherpossible rationalization for this reduction could be high activity ofdifferent enzymes (endoglucanases, xyloglucan, xylanase, etc.) indepolymerization of cell wall (Martinez & Civello, 2008).

4. Conclusion

This paper has given the reasons for the widespread use of O2absorbers in active food packaging. Strawberry has a short life dueto high consumption rate of O2. The results showed that O2absorbers could be used to slow down strawberry metabolism andmold growth since O2 absorber groups maintained the qualitybetter than control group at refrigerated temperatures. It is inter-esting to note that there were no significant differences betweenATCO-100 and ATCO-210 in terms of quality analysis. The secondmajor finding of this study was that FT-NIR represents an innova-tive alternative to monitor fruit quality changes such as strawberry.This study has also highlighted the effectiveness of O2 absorbers onfresh strawberry quality during twenty one days of storage. Aftertwenty one days of storage, control strawberries were notmarketable due to losing of visual quality but still consumableaccording to panelists. Future studies should focus on enhancingquality of strawberries combining with active packaging technol-ogies and innovative preservation methods.

Acknowledgements

This study was founded by the BAP, COMU contract/grantnumber: BAP 2010/151. We would like to thank Standa Industrie(Caen, France) and EMCO Packaging Systems (Kent, UK) (O2absorber sachets) for their support.

M.S. Aday, C. Caner / LWT - Food Science and Technology 52 (2013) 102e109 109

References

Álvarez, M. F. (2000). Revisión: Envasado activo de los alimentos [Review: activefood packaging]. Food Science and Technology International, 6(2), 97e108.

Aday, M. S., & Caner, C. (2010). Understanding the effects of various edible coatingson the storability of fresh cherry. Packaging Technology and Science, 23(8),441e456.

Aday, M. S., & Caner, C. (2011). The applications of ‘active packaging and chlorinedioxide’ for extended shelf life of fresh strawberries. Packaging Technology andScience, 24(3), 123e136.

Aday, M. S., Caner, C., & Rahvalı, F. (2011). Effect of oxygen and carbon dioxideabsorbers on strawberry quality. Postharvest Biology and Technology, 62(2),179e187.

Aguiló-Aguayo, I., Oms-Oliu, G., Soliva-Fortuny, R., & Martín-Belloso, O. (2009).Changes in quality attributes throughout storage of strawberry juice processedby high-intensity pulsed electric fields or heat treatments. LWT e Food Scienceand Technology, 42(4), 813e818.

Ali, Z. M., Chin, L.-H., Marimuthu, M., & Lazan, H. (2004). Low temperature storageand modified atmosphere packaging of carambola fruit and their effects onripening related texture changes, wall modification and chilling injury symp-toms. Postharvest Biology and Technology, 33(2), 181e192.

Almenar, E., Del-Valle, V., Hernández-Muñoz, P., Lagarón, J. M., Catalá, R., &Gavara, R. (2007). Equilibrium modified atmosphere packaging of wild straw-berries. Journal of the Science of Food and Agriculture, 87(10), 1931e1939.

Bobelyn, E., Serban, A.-S., Nicu, M., Lammertyn, J., Nicolai, B. M., & Saeys, W. (2010).Postharvest quality of apple predicted by NIR-spectroscopy: study of the effectof biological variability on spectra and model performance. Postharvest Biologyand Technology, 55(3), 133e143.

Caner, C., & Aday, M. S. (2009). Maintaining quality of fresh strawberries throughvarious modified atmosphere packaging. Packaging Technology and Science,22(2), 115e122.

Caner, C., Aday, M., & Demir, M. (2008). Extending the quality of fresh strawberriesby equilibrium modified atmosphere packaging. European Food Research andTechnology, 227(6), 1575e1583.

Charles, F., Guillaume, C., & Gontard, N. (2008). Effect of passive and active modifiedatmosphere packaging on quality changes of fresh endives. Postharvest Biologyand Technology, 48(1), 22e29.

Charles, F., Sanchez, J., & Gontard, N. (2003). Active modified atmosphere packagingof fresh fruits and vegetables: modeling with tomatoes and oxygen absorber.Journal of Food Science, 68(5), 1736e1742.

Charles, F., Sanchez, J., & Gontard, N. (2006). Absorption kinetics of oxygen andcarbon dioxide scavengers as part of active modified atmosphere packaging.Journal of Food Engineering, 72(1), 1e7.

Chen, C. C., & Paull, R. E. (2001). Fruit temperature and crown removal on theoccurrence of pineapple fruit translucency. Scientia Horticulturae, 88(2), 85e95.

de Huidobro, F. R., Miguel, E., Blazquez, B., & Onega, E. (2005). A comparisonbetween two methods (Warner-Bratzler and texture profile analysis) for testingeither raw meat or cooked meat. Meat Science, 69(3), 527e536.

Del-Valle, V., Hernandez-Munoz, P., Guarda, A., & Galotto, M. J. (2005). Developmentof a cactus-mucilage edible coating (Opuntia ficus indica) and its application toextend strawberry (Fragaria ananassa) shelf-life. Food Chemistry, 91(4), 751e756.

Fan, X. T., & Sokorai, K. J. B. (2005). Assessment of radiation sensitivity of fresh-cutvegetables using electrolyte leakage measurement. Postharvest Biology andTechnology, 36(2), 191e197.

Fan, Y., Xu, Y., Wang, D. F., Zhang, L., Sun, J. P., Sun, L. P., et al. (2009). Effect of alginatecoating combined with yeast antagonist on strawberry (Fragaria � ananassa)preservation quality. Postharvest Biology and Technology, 53(1e2), 84e90.

Feng, G., Yang, H., & Li, Y. (2005). Kinetics of relative electrical conductivity and corre-lationwith gas composition in modified atmosphere packaged bayberries (Myricarubra Siebold and Zuccarini). LWT e Food Science and Technology, 38(3), 249e254.

Fonseca, S. C., Oliveira, F. A. R., & Brecht, J. K. (2002). Modelling respiration rate offresh fruits and vegetables for modified atmosphere packages: a review. Journalof Food Engineering, 52(2), 99e119.

Harker, F. R., Elgar, H. J., Watkins, C. B., Jackson, P. J., & Hallett, I. C. (2000). Physicaland mechanical changes in strawberry fruit after high carbon dioxide treat-ments. Postharvest Biology and Technology, 19(2), 139e146.

Hernandez-Munoz, P., Almenar, E., Del Valle, V., Velez, D., & Gavara, R. (2008). Effectof chitosan coating combined with postharvest calcium treatment on straw-berry (Fragaria x ananassa) quality during refrigerated storage. Food Chemistry,110(2), 428e435.

Huang, M., Kennedy, J. F., Li, B., Xu, X., & Xie, B. J. (2007). Characters of rice starch gelmodified by gellan, carrageenan, and glucomannan: a texture profile analysisstudy. Carbohydrate Polymers, 69(3), 411e418.

Joles, D. W., Cameron, A. C., Shirazi, A., Petracek, P. D., & Beaudry, R. M. (1994).Modified-atmosphere packaging of ‘Heritage’ red raspberry fruit: respiratoryresponse to reduced oxygen, enhanced carbon dioxide, and temperature.Journal of the American Society for Horticultural Science, 119(3), 540e545.

Li, T., Zhang, M., & Wang, S. (2008). Effects of temperature on Agrocybe chaxinguquality stored in modified atmosphere packages with silicon gum filmwindows. LWT e Food Science and Technology, 41(6), 965e973.

Luck, S., Buge, G., Plettenberg, H., & Hoffmann, M. (2010). Near-infrared spectros-copy for process control and optimization of biogas plants. Engineering in LifeSciences, 10(6), 537e543.

Martinez, G. A., & Civello, P. M. (2008). Effect of heat treatments on gene expressionand enzyme activities associated to cell wall degradation in strawberry fruit.Postharvest Biology and Technology, 49(1), 38e45.

Martinez-Ferrer, M., Harper, C., Perez-Muroz, F., & Chaparro, M. (2002). Modifiedatmosphere packaging of minimally processed mango and pineapple fruits.Journal of Food Science, 67(9), 3365e3371.

Miltz, J., & Perry, M. (2005). Evaluation of the performance of iron-based oxygenscavengers, with comments on their optimal applications. Packaging Technologyand Science, 18(1), 21e27.

Moreno, J., Simpson, R., Baeza, A., Morales, J., Muñoz, C., Sastry, S., et al. (2012).Effect of ohmic heating and vacuum impregnation on the osmodehydrationkinetics and microstructure of strawberries (cv. Camarosa). LWT e Food Scienceand Technology, 45(2), 148e154.

Nicolai, B. M., Beullens, K., Bobelyn, E., Peirs, A., Saeys, W., Theron, K. I., et al. (2007).Nondestructive measurement of fruit and vegetable quality by means of NIRspectroscopy: a review. Postharvest Biology and Technology, 46(2), 99e118.

Pitt, R. E. (1992). Viscoelastic properties of fruits and vegetables. In M. A. Rao, &J. F. Steffe (Eds.), Viscoelastic properties of foods. New York: Elsevier.

Rodrigo, D., van Loey, A., & Hendrickx, M. (2007). Combined thermal and highpressure colour degradation of tomato puree and strawberry juice. Journal ofFood Engineering, 79(2), 553e560.

Spaziani, M., del Torre, M., & Stecchini, M. L. (2009). Changes of physicochemical,microbiological, and textural properties during ripening of Italian low-acidsausages. Proteolysis, sensory and volatile profiles. Meat Science, 81(1), 77e85.

Tarr, C. R., & Clingeleffer, P. R. (2005). Use of an oxygen absorber for disinfestation ofconsumer packages of dried vine fruit and its effect on fruit colour. Journal ofStored Products Research, 41(1), 77e89.

Toivonen, P. M. A., & Brummell, D. A. (2008). Biochemical bases of appearance andtexture changes in fresh-cut fruit and vegetables. Postharvest Biology andTechnology, 48(1), 1e14.

Vicente, A. R., Costa, M. L., Martinez, G. A., Chaves, A. R., & Civello, P. M. (2005). Effectof heat treatments on cell wall degradation and softening in strawberry fruit.Postharvest Biology and Technology, 38(3), 213e222.

Vicente, A. R., Ortugno, C., Powell, A. L. T., Greve, L. C., & Labavitch, J. M. (2007).Temporal sequence of cell wall disassembly events in developing fruits. 1.Analysis of raspberry (Rubus idaeus). Journal of Agricultural and Food Chemistry,55(10), 4119e4124.

Yang, Z. F., Zheng, Y. H., Cao, S. F., Tang, S. S., Ma, S. J., & Li, N. (2007). Effects ofstorage temperature on textural properties of Chinese bayberry fruit. Journal ofTexture Studies, 38(1), 166e177.

Zhang, H. Y., Wang, L., Dong, Y., Jiang, S., Cao, H., & Meng, R. J. (2007). Postharvestbiological control of gray mold decay of strawberry with Rhodotorula glutinis.Biological Control, 40(2), 287e292.