Effect of phenylalanine treatment on chilling tolerance and biochemical attributes of grape during postharvest cold storage

Abstract

BACKGROUND: phenylalanine treatment affect on chilling tolerance during postharvest cold storage. OBJECTIVE: This work aimed to investigate exogenous application of phenylalanine (Phe; 0, 15 and 30 mM) on berry phenolic compounds, quality and chilling tolerance of ‘Red Sahebi’ grape during 60 days at 1°C. METHODS: Every 15 days (storage durations were 0, 15, 30, 45, and 60 days), approximately 150 gr of grape bunches were sampled randomly from cool chamber for following physicochemical and microbial analysis. RESULTS: Phe-treated grape at 30 mM maintained higher titratable acid, total sensory score, total soluble solid, soluble sugars, organic acids, and antioxidant capacity compared to control grapes. At the end of storage time, 30 mM Phe-treated grapes showed higher flavonols (11% myricetin, 20% quercetin, and 23% kaempferol), flavanols (22% catechin, 34% epicatechin, and 40% epigallocatechin) and anthocyanins (42% malvidin-3-O-glucoside, 30% delphinidin-3-O-glucoside, 25% cyanidin-3-O-glucoside, and 23% pelargonidin-3-O-glucoside) compared to control samples due to lower polyphenol oxidase but higher antioxidant enzyme activities. Also, 30 mM Phe was found to be effective for berry trans-resveratrol and phenolic acid preservation, displayed less fungal decay. The efficiency of Phe on chilling tolerance was monitored by lower rachis browning, electrolyte leakage, and malondialdehyde but higher abscisic acid content. CONCLUSION: Phenylalanine application retained higher TA, TSS, and vitamin C, antioxidant capacity and total sensory score in treated fruits and alleviates chilling injury of table grape during cold storage.