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    ThesisItemOpen Access
    POST HARVEST BIOCHEMICAL CHANGES IN CABBAGE (Brassica oleraceae var. capitata L.) IN RELATION TO PRE- HARVEST WATER STRESS
    (iochemistry Dept., N.M. College of Agriculture, Navsari Agricultural University, Navsari, 2014-12) Mehta, Amit A.; Singh, Diwakar
    Cabbage (Brassica oleraceae var. capitata L.) is an economically important vegetable crop and is rich source of phytochemicals including amino acids, glucosinolates, flavonoids, vitamins and mineral nutrients. Quality losses in cabbage are in the forms of yellowing of outer leaves, core elongation, internal yellowing in the apex region, leaf abscission and sometimes rootlet development at the core-end. Losses are enhanced by extended storage, higher temperatures, low relative humidity, physical damage, and chilling injury. Many pre-harvest and post harvest factors influence the cabbage. Other pre-harvest factors include climatic conditions and cultural practices. Present study was planned with the hypothesis that pre-harvest water stress may have positive effect on post harvest shelf life in cabbage. Cabbage crop was subjected to water stress during cabbage head development stage and cabbage leaf overlapping stage. Moderate and high water stress was given to the cabbage crop, while recommended dose of irrigation served as control. Highest number of leaves and head height was observed in control after water stress. Highest head weight was observed in treatment T1=High water stress (6 irrigations: Water stress at head development and leaf overlapping stage). The effect of pre harvest water stress was studied on cabbage storage quality during post harvest at 0,2,4,6,8 and 10 days after harvest (dah). Total chlorophyll content was highest in control at 0 day. The highest protein content in leaf was observed in treatment T1=(high water stress) at 10 dah. The highest total free amino acid was found in T1=(high water stress) at 10 day after harvest. The ascorbic acid level in cabbage was appreciably higher in treatment T1 at 0 dah. Chlorophyll and ascorbic acid content decreased with the increasing days after harvest, whereas protein and aminoacids were increasing with the increasing days after harvest. Highest POX activity was recorded in treatment T1 at 10 day after harvest. Highest AAO activity was observed in treatment T1 at 6 dah. The highest PPO enzyme activity was observed in leaves of cabbage in treatment T1 at 10 dah. All these three enzymes (POX, AAO and PPO) showed increased activity with increasing days after harvest. Phenol profiling using HPTLC showed the presence of two phenolic acids i.e. caffeic acid and ferulic acid, which were observed in cabbage head during water stress. Caffeic acid content increased in water stressed cabbage up to 10 dah. While, the percent area of caffeic acid was highest in treatment T1 at 10 dah. The percent area of ferulic acid was highest in treatment T1 at 10 dah. Both of these phenolics also increased with the increasing post harvest storage. GC-MS analysis showed that desulfosinigrin and desulfoglucobrassicin were abundant as glucosinolates in the cabbage head. Desulfosinigrin was decreased due to increasing water stress, while desulfoglucobrassicin was increased due to moderate water stress (T2) but drastically reduced thereafter at high water stress (T1). Protein profiling was also done from cabbage head at different duration of post harvest. At 0 dah all treatments showed similar banding pattern, and at 2 dah it was observed that under treatment T1 & T2 the proteins are over expressed as compared to control T3. ~ 43 kDa and ~ 66 kDa sized protein showed dense band in T1, T2 and T3 (control). With the increasing post harvest duration the protein expression was increased. Among different treatment conditions and post harvest stages no polymorphic protein bands were resolved, but the band intensity was differing among different treatment conditions as well as at different stages of post harvest storage. Thus, it may be concluded that the pre-harvest water stress have some positive effect on the post harvest shelf life and also improves the quality due to decrease in glucosinolates of cabbage.