quality of 'arkin' carambolas with or without …
TRANSCRIPT
Proc. Fla. State Hort. Soc. 104:118-122. 1991.
QUALITY OF 'ARKIN' CARAMBOLAS WITH OR WITHOUT CONDITIONING
FOLLOWED BY LOW-TEMPERATURE QUARANTINE TREATMENT
W. R. Miller and R. E. McDonald
USDA-ARS
2120 Camden Road
Orlando, FL 32803
M. Nisperos-Carriedo
USDA-ARS
600 Avenue S., N.W.
P.O. Box 1909
Winter Haven, FL 33883-1009
Additional index words, postharvest, condition, Caribbean
fruit fly, Anastrepha suspensa (Loew), Averrhoa carambola L.
Abstact. Carambolas (Averrhoa carambola L.) from Florida that
are shipped to some domestic markets require quarantine cer
tification against the Caribbean fruit fly (Anastrepha sus
pensa Loew). 'Arkin' carambolas, with green or yellow peel,
were subjected to a conditioning treatment (15C for 3 days)
prior to a quarantine procedure of cold treatment (1C for 15
days) for the purpose of reducing the development of
symptoms of physiological deterioration. In addition, several
different coatings were applied to the fruit prior to treatment.
After cold treatment and storage for 7 days at 5C plus 3 days
at 15C, green fruit or fruit that were conditioned but not cold
treated, lost 15% more weight than either yellow fruit or those
that were cold-treated without conditioning. Film-wrapping
reduced weight loss 9-fold, and fruit were firmer compared
to fruit with other surface coatings, 1) edible composite of
1.5% Na carboxymethylcellulose and emulsifiers; 2) lanolin;
and 3) noncoated (control). Peel discoloration (bronzing) was
41% higher on yellow fruit compared with green fruit but was
decreased slightly by conditioning before cold treatment. Film-
wrapping significantly improved the maintenance of most
quality attributes and results indicated cold treatment without
conditioning can be successfully applied to carambolas without
adverse physiological deterioration.
A successful cold treatment was developed for grape
fruit by first subjecting them to a conditioning regime at
15C for 7 days prior to exposure to a low-temperature
treatment (Hatton and Cubbedge, 1982). This conditioning
regime significantly and consistently reduced or eliminated
chilling injury damage to the peel of grapefruit during
recommended shipping and storage conditions during and
after cold treatment. In addition to the cold treatment,
investations have also been conducted with carambolas to
determine the effectiveness of heat, such as hot water
(Hallman, 1989; Hallman, 1990; Hallman, 1991; Hallman
and Sharp, 1990) and hot air (Miller et al., 1990; Sharp
and Hallman, in press) as methods for quarantine security
against the CFF. Hot air at temperatures above 47C and
time durations that provide effective mortality to the CFF
were found to cause excessive injury or deterioration to
the fruit during subsequent storage (Miller et al., 1990).
The purpose of this study was to determine (1) if condition
ing of green- or yellow-peel carambolas at 15C for 3 days
prior to cold treatment will reduce fruit deterioration after
cold treatment, and (2) the effect of various fruit coatings
on fruit quality, with or without conditioning and cold treat
ment.
Materials and Methods
Mention of a trademark, warranty, proprietary product, or vendor
does not constitute a guarantee by the U.S. Department ot Agriculture
and does not imply its approval to the exclusion of other products or
vendors that may also be suitable.
118
Carambolas were harvested on February 11, 1991, from
a plantation in Dade County, Florida and supplied by J. R.
Brooks and Son, Inc., Homestead, Florida. The experiment
required an initial pool of freshly-harvested fruit of two
peel color lots, which consisted of 500 mature fruit, each
with green peel or yellow color break. The fruit were wrap
ped in tissue paper and packed 25 fruit (large, average
about 125 g) each into commercial fiberboard boxes and
stored overnight at 5C. Fruit were not washed and no fun
gicide was applied. The following morning, fruit were taken
by air-conditioned automobile to the U.S. Citrus and Sub
tropical Products Laboratory, Winter Haven, Florida, for
treatment preparation. Three replications of 6 fruit each
(18 fruit) for 4 time/temperature treatment regimes (with/
without conditioning and with/without cold treatment) (72
fruit) of each of 2 peel colors (green or yellow) were pre
pared for each of 4 fruit-coating treatments.
The 4 fruit-coating treatments were: Coat 1 - poly heat-
shrink film (W. R. Grace and Co., RD 106-antifog, 60
gauge), Coat 2 - lanolin-covered stem scar, Coat 3 - edible
composite consisting of 1.5% Na carboxymethylcellulose
and emulsifiers (CCE), and Coat 4 - noncoated (control)
fruit. The heat-shrink film was applied to individual fruit
using a hot-wire Weldomatic sealer (Weldotron Corp., Pis-
cataway, New Jersey, Model 6001) and a Weldomatic heat
tunnel. For Coat 2, a thin layer of hydrous lanolin was
applied to the stem scar or localized stem-scar area of fruit
by spatula. The edible coating formulation was applied to
the total surface area of fruit by soft brush, then fruit were
dried with a fan for 1 hr at 21C. Noncoated fruit had no
preparation. After preparation, fruit were re wrapped in
tissue paper (except film-wrapped fruit), and 24 fruit each
(6 fruit each of the 4 coat treatments) were placed into 24
(12 boxes with green-peel fruit and 12 with color-break
fruit) commercial carambola boxes. The fiberboard box
design was two-piece, full-telescoping with 4 ventilation
holes (12 x 32 mm) each on the top and bottom surfaces,
and 2 holes (9 x 45 mm) each on 2 opposite sides. Fruit
were separated from each other with honeycomb partitions,
and foam pads were used between fruit and the inside of
the box top and bottom surfaces. The accessory material
used in the box rendered most ventilation capacity nonfunc
tional.
After fruit were boxed, they were taken to the U.S.
Horticultural Research Laboratory in Orlando, Florida and
placed into 4 time/temperature treatments, 3 boxes each
of green- and yellow-peel fruit. The 4 time/temperature
regimes were: Trt 1 - 1C for 15 days; Trt 2 - conditioning
at 15C for 3 days then 1C for 15 days; Trt 3 - fruit at 5C,
Proc. Fla. State Hort. Soc. 104: 1991.
no conditioning and no cold treatment; and Trt 4 - con
ditioned without cold treatment. The treatment time for
conditioning (15C) and cold treatment (1C) did not start
until core pulp temperature of fruit reached the target
temperature (about 48 hrs). After conditioning and cold
treatments were completed, fruit were placed at 5C
(Campbell et al., 1987) for 7 days, after which all fruit were
held at 15C for 3 days.
Fruit were inspected after the following storage time/
temperature regimes: 1) 12 hr at 5C, 2) completion of 3-day
conditioning (only fruit of Trt 2 and Trt 4), 3) completion
of cold treatment, 4) 7 days at 5C, and 5) 7 days at 5C plus
3 days at 15C. At each inspection, individual fruit were
weighed and subjectively rated for pulp firmness, peel
color, and symptoms of decay, pitting, peel discoloration,
stem-end breakdown, shriveling and deterioration at the
margins of the ribs, as described earlier (Miller et al., 1990).
Fruit maturity was rated mature or immature based on
fruit shape, size, and peel color. Peel color was also meas
ured using the CIE (1976) 'L*', 'a*', and 'b*' color scale
(Minolta colorimeter, Model CR200, Osaka, Japan) on 3
ribs of 3 fruit of each of the 4 coating treatments after each
fruit inspection. The 3 film-wrapped fruit used for color
readings were unwrapped and then rewrapped after
measuring peel color. Air samples for O2 and CO2 determi
nation by GLC were taken by syringe from the periphery
(between fruit and film) of film-wrapped yellow fruit of
Trts 2 and 4 after each inspection. Objective firmness of
fruit was determined using an Instron Food Texture Sys
tem (Canton, MA) with a 9 mm (0.375-inch) diameter cylin
der set to penetrate 3 mm at a speed of 5 cm per min with
the instrument calibrated to 98 N full scale. In addition,
total soluble solids (TSS), acidity (expressed as % anhydrous
oxalic acid), and pH were determined initially from samples
of green and yellow fruit, and after the final inspections.
Taste and texture ratings were scored on a hedonic scale
of 1-100 and made by an informal taste panel of 9 persons
after the final inspection.
All data were averaged over the three replications and
subjected to Duncan's multiple range test or analyzed as a
factorial experiment with 2 peel colors, 2 conditionings, 2
cold treatments, and 4 coatings using ANOVA procedures
(SAS, 1982).
Results and Discussion
Initial condition of carambolas (after 12 hr at 5C).
Prior to conditioning or cold treatment, the fruit were
free of pitting, bronzing, stem-end breakdown, and shrivel
ing; however, the average index value (range 1-5; no dam
age to severe damage, respectively) for fin browning was
1.8 (slight necrotic tissue) and did not differ by fruit peel
color. Carambolas with green peel color were firmer (42.0
N) than yellow fruit (36.0 N). The CIE (1976) color values
for peel of green and yellow fruit were: 'L*' (lightness to
darkness) = 43.2 and 44.1, 'a*' (green to red) = -7.6 and
-5.6, and 'b*' (blue to yellow) = 17.8 and 18.8, respectively.
Percentage of total soluble solids were 7.3 and 8.4, percent
acidity measured 0.21 and 0.18, and pH values were 3.4
and 3.7 for green and yellow fruit, respectively. The initial
taste and texture of yellow fruit was significantly preferred
over that of green fruit.
Proc. Fla. State Hort. Soc. 104: 1991.
After conditioning.
Three days of conditioning at 15C did not significantly
change peel color of green or yellow fruit (about 0.2 change
in index values for 'L*\ 'a*' or 'b*'). Weight loss averaged
1.2% for green fruit and 1.0% for yellow fruit. Conditioned
fruit wrapped in film lost only 0.2% in weight compared
to 1.5% for all other nonwrapped conditioned fruit. Fin
browning was slightly increased to an average index value
of 2.2 during 3 days of conditioning.
After cold treatment.
Average color values for both green and yellow fruit
indicate darkening in color of the peel ('L*' = —1.0 unit
change), an increase in yellow ('b*' = +1.0 unit change)
with a small decrease in greenness ('a*' = +0.5 unit change).
Fruit conditioned prior to cold treatment lost 1.0% more
weight than those not conditioned, and peel color had no
effect on weight loss after cold treatment. Fruit wrapped
in film lost 0.3% weight compared to an average of 3.2%
for all other fruit. Fruit-softening correlated well with
weight loss, as film-wrapped fruit remained firm (index
value 1.0) and all other fruit softened (average index value
1.2) slightly. Peel discoloration described as bronzing de
veloped more on yellow fruit (index value 1.6) compared
to green fruit (index value 1.1). Conditioning had no effect
on the developmnt of bronzing. However, fruit exposed to
cold treatment had slight, but significantly, more bronzing
than those not cold-treated. Only film-wrapped fruit
showed no bronzing.
Stem-end breakdown developed in all fruit not wrapped
in film, and it was slightly more prevalent in yellow com
pared with green fruit and slightly more in conditioned
fruit compared with those not conditioned. Oxygen meas
ured about 21.8% for wrapped yellow fruit in trts 3 and 4,
whereas CO2 was 0.18% and 0.22% for trts 3 and 4, respec
tively.
After 7 days storage at 5C plus 3 days at 15C, final inspection.
Green fruit and those conditioned and not subjected to
the cold treatment, each lost 15% more weight than yellow
or nonconditioned, cold-treated fruit. Film-wrapping re
duced weight loss 9-fold compared to the average of other
fruit surface treatments (Table 1). Wrapped fruit were sig
nificantly firmer than fruit of other surface treatments, and
this difference is shown by the objective measurements of
firmness.
The incidence of peel discoloration described as bronz
ing was 41% higher on yellow-peel fruit than green fruit
after the final inspection. Bronzing was increased slightly
by the cold treatment compared with control fruit not cold-
treated, and bronzing was slightly reduced (by 0.5 index
value) by conditioning prior to cold treatment. Fruit wrap
ped in film developed only a trace of bronzing on very few
fruit, and they were significantly less bronzed than fruit of
other surface coatings. The deterioration of tissue at the
margins of the ribs was significantly reduced in film-wrap
ped fruit compared with the other surface treatments.
Other differences in the amount of browning of rib tissue
among the main factors, although significant, are of little
practical importance.
119
Table 1. Percentage weight loss and condition of green or yellow carambolas with four surface coatings and subjected to a cold treatment (1C for 15 days) with or without prior conditioning (15C for 3 days) and after storage.
Treatment7storage
After 7 days at 5C plus 3 days at
Green fruit
Trtl
Trt2
Trt3
Trt4
Yellow fruit
Trtl
Trt2
Trt3
Trt4
Peel Color
Green
Yellow
Conditioning
No condition
Condition
Cold Treatment
No cold trt
Cold trt
Coatings
Film
Lanolin
Antiox
Control
Main factors or interactions
dP
1 color
1 condition
1 cold trt
3 coat
1 color x cond
1 color x cold
1 cond x cold
3 coat x color
3 coat x cond
3 coat x cold
Weight loss
%
15C
4.1bw
4.6bc
4.6bc
4.9c
3.0a
4.3b
4.2b
4.3b
4.5
3.9
3.9
4.5
4.5
3.9
0.6a
5.4b
5.4b
5.5b
10.5*u
9.11*
7.26*
141.4*
1.03ns
0.54ns
3.59*
1.03ns
0.42ns
0.36ns
Firmnessy
(Sub)
1.4a
1.6bc
1.7c
1.5abc
1.4ab
1.6bc
1.6bc
1.6bc
1.6
1.6
1.5
1.6
1.6
1.5
1.0a
1.8bc
1.6b
1.8c
3.05*
0.10ns
0.18ns
3.05*
0.01ns
0.01ns
0.62*
0.06ns
0.06ns
0.07ns
Firmness
(N)
X10
3.9d
3.3c
3.2c
2.9b
3.3c
3.1 be
2.6a
2.6a
3.3
2.7
3.3
3.0
2.8
3.4
3.4b
3.1a
3.0a
3.0a
4.45*
2.10*
7.62*
0.82*
0.54*
0.05ns
0.29ns
0.18ns
0.15ns
0.03ns
Bronze
scald
3.0bc
2.5b
2.6b
1.6a
3.9d
3.4cd
3.0bc
3.3c
2.4
3.4
3.1
2.7
2.6
3.2
1.3a
3.2b
3.5bc
3.6c
22.43*
3.92*
7.26*
26.52*
1.76ns
0.17ns
0.09ns
1.39*
0.24ns
0.54ns
Stem end
Indexx
1.5ab
1.4a
1.7bc
2.1d
1.6ab
1.5a
1.9cd
2.4e
1.7
1.8
1.7
1.8
2.0
1.5
1.1a
2.0b
2.0b
2.0b
0.40*
0.60*
5.90*
5.34*
0.04ns
0.18ns
1.50*
0.06ns
0.14ns
0.50*
Shrivel
1.2a
1.3ab
1.4bc
1.7d
1.4bc
1.3ab
1.5c
1.7d
1.4
1.5
1.4
1.5
1.5
1.3
1.0a
1.4b
1.6c
1.7c
0.15*
0.30*
1.35*
1.90*
0.14ns
0.02ns
0.24*
0.01ns
0.06ns
0.22*
Fin brn
4.1ab
4.1ab
3.9a
4.4d
4.2bc
4. lab
4.1ab
4.3cd
4.1
4.2
4.1
4.2
4.2
4.1
3.0a
4.4b
4.7c
4.4b
0.06ns
0.67*
0.24ns
13.37*
0.22ns
0.02ns
1.08*
0.04ns
0.19*
0.16ns
no conditioning and no treatments: Trt 1 = cold treatment at 1C for 15 days; Trt 2 = 3 days at 15C (conditioning) and cold treatment; Trt 3 cold treatment; Trt 4 = conditioning and no cold treatment.
yFirmness rating (1 = firm, 2 = fairly firm, 3 = flaccid).
xIndex ratings: 1-5, based on surface area affected. (1 = no disorder; 2 = slight; 3 = moderate; 4 = severe; and 5 = extreme damage.) wmeans separation in columns by Duncan's multiple range test (P < 0.05). vdegrees of freedom.
u*, ns indicates statistical significance at P < 0.05, and nonsignificant.
Stem-end breakdown developed significantly more on
fruit that were conditioned and not subjected to cold treat
ment (Trt 4) compared with fruit of other treatments re
gardless of fruit peel color, but cold treatment reduced
SEB compared with fruit not subjected to the cold treat
ment. Film-wrapped fruit had only a trace of SEB on a few
fruit compared with fruit of all other surface coatings.
Shriveling that developed at the stem end was less prevalent
on cold-treated fruit than those not cold-treated, and
slightly but significantly more SEB was observed on green-
peel fruit and those which were conditioned compared with
yellow or nonconditioned fruit, respectively. Film-wrap
ping eliminated shriveling.
There was only a trace of pitting observed on some fruit
with lanolin and those with the CCE coating, and the devel
opment of pitting was not significantly effected by the main
factors of peel color, conditioning, or cold treatment. No
120
pitting developed on wrapped fruit or those without coating
(controls). There was, however, a tendency for pitting to
develop only on green-peel fruit and those conditioned but
not cold-treated. Brown scald, relatively small (from 2-10
mm in diameter) mottled areas on peel, developed on a
few fruit of all treatments, and film-wrapped fruit had less
brown scald than lanolin or CCE coated fruit, but was simi
lar to the amount observed on control fruit.
As expected, fruit with green peel at the start of the
experiment retained more green than fruit of the initial
yellow-peel lot after the final inspection based on the mag
nitude of color 'a*' and 'b*' values (Table 2). Conditioned
fruit were lighter and had less green peel than noncon
ditioned fruit. Film-wrapped fruit retained more green in
peel color compared with fruit of all other surface treat
ments. Fruit of the green-peel lot had lower TSS, higher
acidity, and lower pH than fruit of the yellow-peel color
Proc. Fla. State Hort. Soc. 104: 1991.
We conclude that the cold treatment as applied in this
study, which has previously been accepted for domestic
quarantine purposes, is not detrimental to carambola. We
suggest that users of cold treatment for carambolas treat
fruit as soon as possible after harvest, and if storage prior
to treatment is required, that fruit weight loss be minimized
by holding them in refrigeration rooms. It should not be
concluded from this study that 15C for 3 days is a recom
mended conditioning temperature for carambola, because
only this single temperature was investigated. In an unpub
lished preliminary study, we observed no difference in qual
ity attributes of carambolas conditioned for 3 or 7 days at
15C prior to cold treatment at 1C for 15 days; therefore,
3-day conditioning was used in this study. Future investiga
tions should be conducted which include other conditioning
temperatures and time durations to determine potential
beneficial effects on fruit quality during low-temperature
treatment.
This study also shows that film wrapping of carambolas
significantly improved the maintenance of most quality at
tributes included in this report compared to other surface
coatings or control fruit. Fruit appearance was improved
due to a reduction in bronzing, and weight loss was reduced
9-fold and fruit remained very firm with a corresponding
near elimination of SEB and shriveling. No beneficial effect
was provided by the CCE coating, which was included in
this study primarily to determine its effect on peel discolora
tion. Although the CCE coating compound was unstable at
5C (sticky) compared with 15 or 21C, the fruit responded
similarly as did those with lanolin at the stem scar and
control fruit.
Literature Cited
1. Campbell, C. A., D. J. Huber, and K. Koch. 1987. Postharvest re
sponse of carambolas to storage at low temperatures. Proc. State
Hort. Soc. 100:272-275.
2. Gould, W. P. and J. L. Sharp. 1990. Cold-storage quarantine treat
ment for carambolas infested with the Caribbean fruit fly (Diptera:
Tephritidae). J. Econ. Entomol. 83:458-460.
3. Hallman, G. J. 1989. Quality of carambolas subjected to hot-water
immersion quarantine treatment. Proc. Fla. State Hort. Soc. 102:155-
156.
4. Hallman, G. J. 1990. Survival and reproduction of Caribbean fruit
fly (Diptera: Tephritidae) adults immersed in hot water as third
instars. J. Econ. Entomol. 83:2331-2334.
5. Hallman, G. J. and J. L. Sharp. 1990. Hot-water immersion quaran
tine treatment for carambolas infested with Caribbean fruit fly (Dipt
era: Tephritidae). J. Econ. Entomol. 83:1471-1474.
6. Hallman, G. J. 1991. Quality of carambolas subjected to postharvest
hot-water immersion and vapor-heat treatments. HortScience
26:286-287.
7. Hatton, T. T. and R. H. Cubbedge. 1982. Conditioning Florida
grapefruit to reduce chilling injury during low-temperature storage.
J. Amer. Hort. Sci. 107:57-60.
8. Miller, W. R., R. E. McDonald, and J. L. Sharp. 1990. Condition of
Florida carambolas after hot-air treatment and storage. Proc. Fla.
State Hort. Soc. 103:238-241.
9. Sharp, J. L. and G. J. Halman. 199X. Hot-air quarantine treatment
for carambolas infested with the carambola fruit fly (Diptera: Tep
hritidae). J. Econ. Entomol. (accepted for publication, Sept. 1991).
10. SAS Institute. 1982. SAS User's Guide: Statistics. SAS Institute. Cary,
NC.
Proc. Fla. State Hort. Soc. 104:122-125. 1991.
DEVELOPMENT OF AN EDIBLE COATING FOR
EXTENDING POSTHARVEST LIFE OF SELECTED FRUITS AND VEGETABLES
Myrna O. Nisperos-Carriedo,
Elizabeth A. Baldwin and Philip E. Shaw
U.S. Citrus and Subtropical Products Laboratory*
600 Avenue S, N.W.
P.O. Box 1909
Winter Haven, FL 33883-1909
Additional index words. Shelf-life, permeability, ripening, en
zymatic browning, flavor volatiles.
Abstract. An edible composite coating was developed and
tested on various fresh fruits and vegetables for extension of
shelf-life by retardation of ripening, prevention of enzymatic
browning or retention of fresh flavor and aroma. The USDA
experimentaf coating retarded ripening in some climacteric
fruits such as tomatoes, mangoes, papayas and bananas, as
evidenced by color and ethylene data differences. Valencia
oranges showed increases in some flavor volatiles including
'South Atlantic Area, Agricultural Research Service, U.S. Department
of Agriculture.
Mention of a trademark or proprietary product is for identification
only and does not imply a warranty or guarantee of the product by the
U.S. Department of Agriculture over other products which may also be
suitable.
122
alcohols, and the increases were greater in those coated with
a commercial water wax. The undesirable enzymatic browning
reactions in mushroom slices were prevented by the applica
tion of the edible coating. The anti-browning property of the
coating was further improved by the incorporation of an anti-
oxidant and a chelator.
Fruits and vegetables undergo progressive deterioration
after harvest due to desiccation, microbial growth and
biochemical processes. Several processes have been de
veloped that extend product shelf-life by retarding respira
tion rate and moisture loss, and by inhibiting the growth
of aerobic microorganisms. Some of these processes include
controlled atmosphere, hypobaric storage and the use of
protective films. Recently, the application of edible coatings
that can simulate controlled atmosphere storage to prolong
product freshness is becoming a popular concept (Nisperos-
Carriedo et al., 1990; Nisperos-Carriedo and Baldwin,
1988; Dhalla and Hanson, 1988; Kester and Fennema,
1986; Banks, 1985; Lowings and Cutts, 1982). Edible coat
ing is defined as a thin layer of material which can be eaten
by the consumer and which provides a barrier to moisture,
oxygen and solute movement for the food (Guilbert, 1986).
It can be developed from proteins, polysaccharides, lipids
or from a blend of these groups of materials (Kester and
Fennema, 1986). The ability of these coatings to extend
Proc. Fla. State Hort. Soc. 104: 1991.