The effect of modified atmosphere packaging on postharvest performance of two loquat cultivars

Abstract

Loquat (Eriobotrya japonica (Thunb.) Lindl.) is the only fruit tree crop in the Mediterranean zone with ripening period during early spring, particularly when specific preharvest practices are applied such as cultivation under plastic cover. Loquat fruit is characterised by its refreshing taste and it is highly appreciated by consumers. However, loquat fruit is characterised by relatively short storage potential partially due to senescence and/or chilling related disorders. The aim of the current study was the evaluation of Xtend® packaging as a means of modified atmosphere packaging (MAP) on postharvest performance of fruit from the main loquat cultivars grown in Cyprus, namely ‘Karantoki’ and ‘Morphitiki’. Fruit were subjected to cold storage in conventional refrigerator (4°C) for 3 weeks and subsequently allowed at room temperature for 0, 2, 4 and 7 days, respectively. For each treatment, 30 fruits were used to determine weight loss, peel colour differentiations (CIEL*, a*, b*), flesh firmness (Texture analyser, Stable Micro Systems), soluble solids content (SSC) and titratable acidity (TA). ‘Morphitiki’ presented better phenotypic appearance compared to ‘Karantoki’ after extended storage, mainly due to reduced weight loss. Application of MAP significantly reduced weight loss after removal from cold storage. However, extended maintenance at room temperature (4 and 7 days) deteriorated the performance of both cultivars. As a technological perspective of the current study, data suggest that ‘Morphitiki’ fruit subjected to MAP can be refrigerated up to 3 weeks, provided they are consumed within two days after removal from storage.

Full text

Acta Hortic. 1242. ISHS 2019. DOI 10.17660/ActaHortic.2019.1241.108
Proc. III Int. Symp. on Horticulture in Europe – SHE2016
Eds.: P. Kalaitzis et al.
729
The effect of modified atmosphere packaging on
postharvest performance of two loquat cultivars
M. Hadjipieri, K. Gavriel, G. Sismanidis and G.A. Manganaris
Cyprus University of Technology, Department of Agricultural Sciences, Biotechnology & Food Science, 3603
Lemesos, Cyprus.
Abstract
Loquat (Eriobotrya japonica (Thunb.) Lindl.) is the only fruit tree crop in the
Mediterranean zone with ripening period during early spring, particularly when
specific preharvest practices are applied such as cultivation under plastic cover. Loquat
fruit is characterised by its refreshing taste and it is highly appreciated by consumers.
However, loquat fruit is characterised by relatively short storage potential partially due
to senescence and/or chilling related disorders. The aim of the current study was the
evaluation of Xtend® packaging as a means of modified atmosphere packaging (MAP)
on postharvest performance of fruit from the main loquat cultivars grown in Cyprus,
namely ‘Karantoki’ and ‘Morphitiki’. Fruit were subjected to cold storage in
conventional refrigerator (4°C) for 3 weeks and subsequently allowed at room
temperature for 0, 2, 4 and 7 days, respectively. For each treatment, 30 fruits were used
to determine weight loss, peel colour differentiations (CIEL*, a*, b*), flesh firmness
(Texture analyser, Stable Micro Systems), soluble solids content (SSC) and titratable
acidity (TA). ‘Morphitiki’ presented better phenotypic appearance compared to
‘Karantoki’ after extended storage, mainly due to reduced weight loss. Application of
MAP significantly reduced weight loss after removal from cold storage. However,
extended maintenance at room temperature (4 and 7 days) deteriorated the
performance of both cultivars. As a technological perspective of the current study, data
suggest that ‘Morphitiki’ fruit subjected to MAP can be refrigerated up to 3 weeks,
provided they are consumed within two days after removal from storage.
Keywords: Eriobotrya japonica, cold storage, weight loss, soluble solids content, titratable
acidity, chilling
INTRODUCTION
Loquat is a highly perishable commodity with relatively short shelf life period (Tian et
al., 2007), while fruit can be cold stored at high relative humidity for up to 3 weeks (Kader,
2002). Due to its perishability, alternative methods to conventional cold storage (CS) with the
aim to expand its market life were dissected such as: modified atmosphere packaging (MAP)
(Ding et al., 2006; Pareek et al., 2014), controlled atmosphere (Ding et al., 2006), paper bags
packaging and 1-methylcyclopropene (Zheng et al., 2010; Cao et al., 2011). The minimum safe
cold storage temperature ranges from 0 to 10°C, highly dependent on the sensitivity of cultivar
on chilling injury (CI) symptoms. Loquat fruits conditioned at 1°C for 30 days in polyethylene
bags with small holes kept their original quality and chemical characteristics intact (Ding et
al., 1998). Cold storage at 5°C in polyethylene bags of 20 μm width and with internal gas
content 4% Ο2 and 5% CΟ2 showed better performance, while organic acids and carotenoid
contents registered higher values compared to control (Ding et al., 2002).
Loquat cultivation in Cyprus is mainly based in two traditional cultivars, namely
‘Morphitiki’ and ‘Karantoki’ (Figure 1), for which relatively few data exist about their storage
potential and postharvest performance. ‘Morphitiki’ has rounded to egg fruit shape, juicy
white to yellow flesh with refreshing taste (Goulas et al., 2014). ‘Karantoki’ bears larger pear-
shaped fruit and shows earlier fruit maturation (ca. 15 days earlier than ‘Morphitiki’). MAP
treatment has been successfully applied in an array of commodities; in the current study its
effect in loquat fruit was dissected.

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Figure 1. Mature ‘Karantoki’ (a) and ‘Morphitiki’ (b) fruits with distinct anatomical
properties.
MATERIALS AND METHODS
Fruit material (‘Morphitiki’ and ‘Karantoki’) were harvested from a covered commercial
orchard (Episkopi, Limassol, Cyprus), based on size uniformity and external colour. Fruit were
initially used for the determination of physical dimensions and colour and subsequently for
analytical studies as described below. For each cultivar and storage treatment, lots of 30 fruits
(three 10-fruit sub-lots) were used. Fruit (control and MAP-treated) were placed into a
conventional refrigerator at 4°C (CS) for 3 weeks and subsequently evaluated after 0, 2, 4 and
7 days shelf life, respectively. The specific packaging is used worldwide for storing an array of
commodities, such as pomegranates, cherries, bananas, fresh vegetables, citrus and stone
fruits (DECCO-UPL 2005). Weight loss (WL), colour parameters, flesh firmness, soluble solids
content (SSC) and titratable acidity (TA) were determined.
Weight loss (WL) % was monitored as follows: (Α-Β)/Α×100, where A was the fruit
weight at harvest and B was the fruit weight after the shelf life period. The colour parameters
CIE L* (brightness or lightness; 0 = black, 100 = white), a* (-a* = greenness, +a* = redness) and
b* (-b* = blueness, +b* = yellowness) were measured in the peel tissue at both sides of each
fruit, using a Minolta chromatometer (CR-400, Konica Minolta). Flesh firmness (FF) was
determined on opposite sides of the equator of each fruit with a penetrometer (TA.XT plus,
Stable Micro Systems, Surrey, UK) fitted with a 3-mm plunger at 1 mm s-1 speed and 5 mm
depth; the two readings were averaged for each fruit and results expressed in g. Soluble solids
content (SSC) of the juice was measured with a digital refractometer (DR103L, Sun
Instruments Corp., USA) and data were expressed as %. Titratable acidity (TA) was measured
using an automatic titrator (DL22 Mettler Toledo titrator, Mettler-Toledo, Inc., Columbus, Ohio,
USA) and determined by titrating 5 mL of juice with 0.1 N NaOH to a pH end point of 8.1.
Results were expressed as g malic acid 100 g-1 FW. Ripening index (RI) was calculated as the
SSC/TA ratio.
Data were analysed based on the ANOVA method according to 2×1×8-9 factorial design
(2 cultivars × 1 method × 8-9 treatments) with 30 replications for treatments combinations.
Means were compared with the Duncan test at P≤0.05. All statistical analyses were carried
out using the software package SPSS v22.0 (SPSS Inc., Chicago, USA).
RESULTS AND DISCUSSION
Modified atmosphere packaging led to reduced weight loss (Table 1), in accordance with
similar studies in other loquat cultivars (Amoró s et al., 2008). However, extended shelf life (4
or 7 days) after removal from cold storage led to substantially high weight loss in all cases.
‘Karantoki’ fruit showed higher weight losses after removal from cold storage, and intense
shriveling after extended shelf life period (Figure 2).

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Table 1. Weight loss (%), ripening index (SSC/TA), flesh firmness (g) of ‘Karantoki’ and
‘Morphitiki’ fruits at harvest and after refrigerated storage (cold storage, CS) with or
without modified atmosphere packaging (MAP) and additional maintenance at room
temperature (shelf life, SL) for 0, 2, 4 and 7 days, respectively. Results are the means
± standard error. The statistical analysis for each parameter shows the statistical
difference between the two cultivars and the storage treatments.
Treatment
Weight loss (%)
Ripening index (SSC/TA)
Flesh firmness (g)
Karantoki
Morphitiki
Karantoki
Morphitiki
Karantoki
Morphitiki
Harvest
37.3±1.2g
19.3±2.5i
105.4±4.5f
130.1±7.2 cde
3 w CS + 0 d SL
3.5±0.2i
3.6±0.1i
67.6±5.0ef
35.7±8.8gh
125.3±4.7de
142.0±3.4 abcd
3 w CS + 2 d SL
7.5±0.4f
6.4±0.2g
77.9±1.5bcde
40.7±0.7g
142.0±9.6abcd
135.5±4.3 bcde
3 w CS + 4 d SL
8.7±0.3d
9.6±0.2e
83.6±2.0bcd
68.9±4.6ef
126.4±4.4 cde
133.5±4.9 bcde
3 w CS + 7 d SL
14.2±0.6a
10.5±0.3c
99.9±2.4a
76.6±2.1cde
119.0±6.8 ef
130.4±4.7 cde
3 w ΜΑΡ + 0 d SL
0.7±0.04j
0.7±0.04j
63.1±3.07f
25.3±2.4fhi
145.3±5.6 abc
150.7±4.9 ab
3 w ΜΑΡ + 2 d SL
5.0±0.2h
3.4±0.1i
77.8±4.6bcde
35.7±3.8gh
135.1±6.6 bcde
154.8±5.1a
3 w ΜΑΡ + 4 d SL
9.3±0.3e
7.2±0.4f
88.3±2.1b
42.2±4.5g
139.2±5.5 abcd
150.6±5.4ab
3 w ΜΑΡ + 7 d SL
15.0±0.5b
1.8±0.5d
86.2±3.82bc
73.9±0.6def
128.7±5.2 cde
141.7±3.1 abcd
Figure 2. Phenotypic appearance of ‘Karantoki’ (a) and ‘Morphitiki’ fruits (b) after 3-week
refrigerated storage under modified atmosphere packaging and additional
maintenance at room temperature (shelf life, SL) for 4 days.
Flesh firmness registered higher values after removal from cold storage in both cultivars
compared to harvest, both in control and MAP-treated fruit; ‘Morphitiki’ fruit presented
higher firmness values than ‘Karantoki’ (Tabl e 1 ). Notably, an increase in tissue firmness of
specific loquat cultivars during postharvest was reported, being attributed to lignin
biosynthesis (Cai et al., 2006); while in other loquat cultivars, extended storage (6 weeks) led
to firmness reduction (Amoró s et al., 2008).
Ripening index increased with the progress of shelf life period (Table 1). ‘Karantoki’
fruit possessed higher values, mainly due to lower titratable acidity, particularly after
extended shelf life, as elsewhere described (Goulas et al., 2014). Both cultivars presented
higher RI after CS with or without MAP treatment after shelf life of 7 days. Modifications in
SSC were less intense compared to TA during the shelf life period for both cultivars (data not
shown).
Regarding colour parameters, L* values went descending compared to harvest in both
cultivars (Table 2). According to Amoró s et al. (2008), L* values reduced in loquat fruit after
CS treatments and subsequent maintenance at room temperature with only a slight decrease
when the fruit was treated with MAP and then maintained at room temperature. The a*
parameter showed an increase during SL after removal from CS, registering the highest values
in ‘Morphitiki’ fruits after postharvest maintenance for 4 and 7 days, both in control and MAP-
treated fruits. This is a typical phenomenon, also monitored in other loquat cultivars where

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the a* parameter was increased during SL after CS treatment (Amorós et al., 2008). The b*
values went descending compared to harvest in both cultivars for both treatments. According
to Amoró s et al. (2008), the b* parameter showed a decrease during CS as well as CS and SL,
while MAP treatment did not affect it. Notably, the ratio a*/b* in our study indicated that the
‘Morphitiki’ cultivar had a more desirable colour which, over time, got deeper but was not
affected by the MAP treatment as it showed no statistical difference in all corresponding
treatments (Table 2).
Table 2. Colour parameters for ‘Karantoki’ and ‘Morphitiki’ fruits at harvest and after
refrigerated storage (cold storage, CS), with or without modified atmosphere
packaging (MAP) and additional maintenance at room temperature (shelf life, SL) for
0, 2, 4 and 7 days, respectively. Results are the means ± standard error. The statistical
analysis for each parameter (L*, a*, b* and a*/b* ratio) shows the statistical
difference between the two cultivars and the treatments.
Treatment
L*
a*
b*
a*/ b*
Karantoki
Morphitiki
Karantoki
Morphitiki
Karantoki
Morphitiki
Karantoki
Morphitiki
Harvest
64.6±
0.4b
67.7±
0.3a
2.6±
0.4jk
5.1±
0.4efg
46.0±
0.6b
48.5±
0.6a
0.06ij
0.11 gh
3 w CS +
0 d SL
49.8±
1.1gh
48.4±
1.2h
3.2±
0.2ij
5.5±
0.3def
38.7±
0.8hi
36.9±
0.7i
0.09hi
0.15cd
3 w CS +
2 d SL
53.8±
0.9def
53.9±
0.9def
4.1±
0.2ghi
6.8±
0.3b
40.5±
0.7fgh
41.6±
0.7efg
0.10 gh
0.17bc
3 w CS +
4 d SL
54.7±
0.8cdef
55.9±
0.6cde
4.8±
0.8efgh
8.1±
0.3a
42.4±
0.6def
43.8±
0.6cde
0.11fg
0.19b
3 w CS +
7 d SL
54.9±
1cde
53.1±
1.2ef
6.2±
0.3bcd
8.9±
0.3a
44.5±
0.8bcd
42.0±
1.3ef
0.14def
0.22a
3 w ΜΑΡ +
0 d SL
56.3±
0.8cd
53.7±
1.0def
2.8±
0.2jk
5.6±
0.4cde
42.1±
0.6ef
40.3±
0.7fgh
0.07ij
0.14def
3 w ΜΑΡ +
2 d SL
51.8±
0.9fg
49.0±
1.3h
3.9±
0.2hi
6.6±
0.4bc
40.3±
0.6fgh
38.9±
0.8hi
0.10 gh
0.17bc
3 w ΜΑΡ +
4 d SL
49.2±
1.0gh
57.4±
0.8c
4.6±
0.2efgh
8.1±
0.4a
39.3±
0.7gh
45.3±
0.8b
0.12efg
0.18b
3 w ΜΑΡ +
7 d SL
56.3±
0.9cd
58.2±
1.3cde
6.4±
0.4bcd
8.9±
0.4a
44.6±
1.0bcd
42.6±
1.4def
0.14cde
0.22a
CONCLUSIONS
Results indicated the beneficial effect of MAP in maintaining postharvest appearance of
loquat fruit, even under extended conventional refrigerated storage, provided that they will
be consumed in a short period after removal from storage. Furthermore, ‘Morphitiki’ fruits
presented appreciable better appearance compared to ‘Karantoki’ fruit; the latter were
characterized by high levels of weight loss that led to both quantitative and qualitative losses,
particularly after extended shelf life periods (Figure 2). Therefore, the significance of
genotype is also highlighted in the current study.
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