الفهرس 
Effect of Postharvest Modified Atmosphere Packaging and/or Chitosan on Extending the Fruit Ripening Period and Quality Retention of Late Swelling Peach FruitOnly 14 pages are availabe for public view
 |  | from | 74 |  |  |
| | | from | 74 | | |
Abstract
The present study was carried out during 2016 and 2017 postharvest seasons on the
Late Swelling peach (Prunus Persica, L.) cultivar. Fruits were harvested at the early ripe stage (during the first week of June) and immediately transported to the postharvest laboratory of the Pomology Department, Faculty of Agriculture, Alexandria University.
Fruits were washed, air dried and sorted to remove any unsuitable fruits (mechanical damage, injured and discolored). Sorted fruits were divided into three groups for dipping in
three levels of chitosan solution (Chi.0, Chi.1 and Chi.2) for one minute then air dried.
Fruits of each group were packed in four types (72kg/type) of modified atmosphere
bagging (MAP0, MAP1, MAP2 and MAP3). In a randomized complete block design
(RCBD), 48 experimental units were arranged (3 Chi. × 4 MAP × 4 replicates). The Chi.1
was 1.5 and 3 while the Chi.2 was 3 and 6 g/L in the first and second season, respectively.
All experimental units were held at 10˚C and 90-95% R.H for 5 weeks in order to
investigate fruit shipping and/or marketability. The experiment was split plot design with two ways analysis of variance (ANOVA). The obtained results are summarized as follow:
Fruit physical characters
The MAP maintained fruit firmness from declining during storage, with no
significant differences occurred between the MAP2 and MAP3 in both seasons. The Chi.1 and Chi.2 decreased fruit firmness with no significant difference obtained between Chi.1 and Chi.2. In addition, the three types of MAP accompanied with any concentration of chitosan resulted in higher values of fruit firmness than unpacked fruits and treated with
any chitosan concentrations.
The packaging treatments affected the L* value during storage for ten days. The
Chi.1 and Chi.0 treatment had similar L* values and lower than the Chi.2 in the first season, however, these differences were not enough to be significant. The MAP0 + Chi.2 treatment had higher L* value than MAP0 + Chi.0 in the first season only. The three types of MAP in
both season and only MAP2 in the second increased the hº value with no significant differences obtaining among the three MAP1 types in both seasons. The hº value did not differ in both chitosan concentrations when compared with the undipped control fruits.
Results of the both seasons showed that the hº value did not differ significantly among the
MAP0 + Chi.0, Chi.1, and Chi.2. The three types of modified atmosphere packaging resulted in similar C value and significantly lower than the unpacked control fruits in the first
season only. The chitosan dipping did not affect the C value. The MAP0 + Chi.1 or Chi.2 resulted in lower C value than MAP0 + Chi.0 in the first season.
Fruit chemical characters All types of MAP maintained fruit acidity content during cold storage without
difference occurring among the three types. The chitosan dipping treatments maintained 57 the fruit acidity content in the 2017 season from declining during storage at 10oC.
Generally, the combination of the MAP and chitosan treatments had no significant influence on fruit acidity content.
The MAP1 and MAP2 resulted in higher TSS content during cold storage than the
unpacked control fruits in the first season, while, in the second season, the MAP3 gave higher fruit TSS content than MAP1. Neither of the chitosan levels affected fruit TSS content during both seasons. Moreover, results of 2016 showed that MAP2 + Chi.0 resulted
in higher TSS than MAP0 + Chi.1, MAP0 + Chi.2 and MAP3 + Chi.0.
The MAP1 (in both season) and MAP2 and MAP3 (in the second season) had lower
values of total sugars than the untreated fruits, with no significant difference occurring the three MAP types. The MAP1 and MAP2 had lower reducing sugars than MAP0, and the
MAP1 and MAP3 resulted in lower non-reduce sugars than MAP0 in the second season only. Both chitosan concentrations did not significantly affect the fruit reducing, nonreducing and total sugars. Generally, no interaction influence on fruit reducing, nonreducing and total sugars was obtained between the MAP and the chitosan applications The MAP1 and MAP2 in both seasons and MAP3 in the second one maintained chlorophyll content from declining during storage, with no significant differences noticed
among them. The Chi.1 dipping treatment had lower total chlorophyll content than the control and the Chi.2. in the first season only. In the first season MAP0+Chi.2 had higher
total chlorophyll content than the MAP0 + Chi.0. The MAP1 and MAP2 combined with the Chi.0 indicated higher total chlorophyll content than MAP0 combined with Chi.1, in both seasons, and MAP0 combined with Chi.2, in the second season during storage.
MAP1, MAP2 and MAP3 had similar values of fruit vitamin C content and higher
than the MAP0 during storage. Whereas, in the first season, the MAP0, MAP1 and MAP3had similar values of vitamin C content and lower than the MAP2. The Chi.1 had higher value of vitamin C than the Chi.0 and Chi.2 in the first season only and no significant interaction effect was obtained.
All types of modified atmosphere packing had similar anthocyanin content and lower than the unpacked fruit during storage for ten days. Neither of chitosan concentrations affected the fruit anthocyanin content. In general, no significant differences obtained
among any types of MAP accompanied with the Chi.1 or Chi.2 in both seasons.
The MAP2 had lower total carotenoids content than MAP0 and MAP1. Neither of
chitosan concentrations affected the fruit total carotenoids content. In general, no significant interaction influence was obtained.
Neither MAP types or chitosan dipping treatments and their combinations affected fruit total phenols content during storage for ten days.
58 All types of MAP (except MAP1 in the second season) decreased significantly fruit electrolyte leakage percent during storage for ten days. The Chi.2 decreased fruit electrolyte leakage in the second season. Additionally, MAP2 + Chi.1 or Chi.2, MAP3 + Chi.2 did not differ among each other and resulted in lower percent than MAP1 + Chi.2 in
the first season, while in the second one, The MAP1, MAP2 or MAP3 + Chi.1 or MAP1 + Chi.2 did not differ among each other and resulted in higher percent than MAP2 + Chi.2.