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EFFECT OF HARVESTING DATES, ANTIOXIDANTS AND STORAGE TEMPERATURE ON RAISIN RECOVERY AND QUALITY OF SEEDLESS GRAPE VARIETIES

KrishiKosh

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Title EFFECT OF HARVESTING DATES, ANTIOXIDANTS AND STORAGE TEMPERATURE ON RAISIN RECOVERY AND QUALITY OF SEEDLESS GRAPE VARIETIES
 
Creator VENKATRAM AMBOTU
 
Contributor Dr. A. S. Padmavathamma
 
Subject sensory attributes.,quantitative and qualitative characteristics,antioxidants
 
Description The investigation was planned and executed in the Grape Research Station, Rajendranagar, Dr.Y.S.R. Horticultural University during the year 2012–14, to study the influence of harvesting dates, antioxidants (ascorbic acid, AA and benzyl adenine, BA) with alkaline emulsion of ethyl oleate (AEEO) pre-drying treatments and storage temperature (5±1oC, 18±1oC and ambient condition) on recovery and quality of dried off (tray dried) or dried-on-vine (DOV) raisins prepared from five seedless varieties of grapes viz., Thompson Seedless, 2A Clone, Sonaka, Manik Chaman and Merbein Seedless. The four experiments were laid out in factorial completely randomized design with three replications. The raisins was evaluated for quantitative and qualitative characteristics viz., green, brown and mixed colored raisins, raisin recovery, average raisin weight, raisin yield, raisin wastes, drying ratio, drying rate, drying time, raisin size, raisin surface texture, moisture content, total soluble solids (TSS), acidity, brix-acid ratio, sugars (total, reducing, non-reducing), ascorbic acid, Hunter color L* (lightness), a* and b* values, weight loss and sensory attributes.
Harvest date results showed that raisins prepared from well matured grapes i.e. harvested between 19th April to 1st May claimed lowest brown and mixed colored raisins, and correspondingly increased green colored raisins. Significantly maximum raisin recovery of 26.20% was recorded in Thompson Seedless harvested on 19th April. Raisin weight, yield, size, TSS, brix-acid ratio, sugars and Hunter color L*, -a* (greenness) and b* (yellowness) values increased with succeeding harvest dates and recorded maximum in fifth harvest. Thompson Seedless raisins were superior compared to others in term of quality. The drying ratio, drying time, moisture content and acidity were lowest in fifth (19th April to 1st May). The grapes dried early in cultivar Merbein Seedless and it takes only 13.27 days to dry followed by 2A Clone, Thompson Seedless, Manik Chaman and Sonaka in order. The organoleptic score for color and appearance, texture, flavour, taste and overall acceptability of raisins was noted by the Panelists and maximum recorded in Manik Chaman which was comparable with Thompson Seedless.
The grapes were dried in ventilated rooms in trays after pre-drying treatment with various concentrations of antioxidants (500, 750 and 1000 ppm of AA and 50, 100, 150 ppm of BA) with alkaline emulsion of ethyl oleate, among which AEEO with AA 1000 ppm showed maximum recovery, greenness, weight, yield, size, TSS, brix-acid ratio, sugars and lowest drying ratio, drying time, acidity, brown and mixed colored raisins. Raisins prepared by AEEO with AA 1000 ppm as a pretreatment showed their effectiveness to retain higher L*, -a* (greenness) and b* (yellowness) values, color homogeneity and sensory attributes. Regarding varieties, Thompson Seedless raisins were superior for studied characteristics. The Manik Chaman raisins were superior for sensory attributes, which was on par with Thompson Seedless whereas it was lowest for Sonaka.
For dry-on-vine (DOV) raisin making, AEEO with AA 1000 ppm pre-drying treatment showed their effect to record highest average raisin weight, raisin yield, raisin size, TSS, brix- acid ratio, sugars (total, reducing and non-reducing), ascorbic acid and L*, a* and b* values. Significantly highest ascorbic acid content and lowest acidity and moisture content of raisins was recorded in AEEO with AA 1000 ppm pretreatment. Regarding varieties, Manik Chaman were superior for DOV raisin making with their rich contribution of bright colour and excellent raisin qualities, which was comparable with Thompson Seedless. The results also revealed that Merbein Seedless is dried in short time, it was taken 20.03 days to dry followed by 2A Clone, Thompson Seedless, Manik Chaman and Sonaka.
The raisins stored at 5±1oC in 400 guage LDPE bags recorded maximum moisture content, TSS, brix-acid ratio, sugars, ascorbic acid and L*, a* and b* values. Raisins stored at 5±1oC retained greenness upto 93.68 days followed 18±1oC (78.38 days), whereas at ambient condition the greenness retained only 35.09 days. With respect to varieties, Thompson Seedless raisins were good for retention of greenness (77.46 days) and quality during storage. The quality of raisins was decreased with advancement of storage temperature and storage period.
From this finding it can be concluded that the Thompson Seedless bunches were harvested between 9th to 19th April in Hyderabad area, then dipped in AEEO with ascorbic acid 1000 ppm as a pre-drying treatment and raisins stored in 5±1oC in 400 guage LDPE bags was retained maximum greenness as well as quality of raisins.
 
Date 2016-07-25T10:37:31Z
2016-07-25T10:37:31Z
2015-04
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/69664
 
Language en
 
Format application/pdf
 
Publisher Dr.Y.S.R. HORTICULTURAL UNIVERSITY