Storage and post-cold storage evaluation of exotic apple varieties harvested at different maturity levels using destructive and non- destructive techniques

Most of the studies have used destructive techniques to evaluate the storage parameters while various authors have explored acoustics and machine vision to determine the firmness and defects in apples respectively. However, in all the reported studies destructive and non-destructive techniques have been employed separately to study the storage behaviour of apples. In the present study both destructive and non-destructive techniques were used and were correlated to predict the storage behaviour of three exotic apple varieties; Gala Redlum, Red Velox and Super Chief grown under temperate conditions Himalayan conditions of Kashmir for the first time. Acoustic coefficient, firmness, pectin, juice yield, acidity, non-reducing sugars and overall acceptability decreased, whereas, cumulative physiological loss in weight (CPLW) and rot percentage increased from H1 to H3 irrespective of variety and storage conditions. Total soluble solids, total sugar, reducing sugar and anthocyanin content showed slight increase followed by a progressive decline under both the storage conditions. Early harvested apples (H1) showed higher spoilage and color change as compared to mid (H2) and late (H3) harvested apples irrespective of variety and storage conditions. Overall apples harvested at H1 had a shelf life of 60 days under ambient conditions and 130 days under cold storage conditions with a post-cold storage life of 10 days. Apples harvested at H2 had a shelf life of 75 days under ambient conditions and 170 days under cold storage conditions with a post-cold storage life of 15 days, while apples harvested at H3 had a shelf life of 60 days under ambient conditions and 110 days under cold conditions with a post-cold storage life of 10 days. Correlation analysis between destructive and non-destructive parameters was also performed. Acoustic coefficient showed significant positive correlation with firmness measured using texture analyzer (r = 0.71; 0.92, p <= 0.01) and negative correlations with starch content (r = -0.76, p <= 0.01) and CPLW (r = -0.72, p <= 0.01). Inference drawn from the study was that in future acoustics can emerge as a quick and reliablenon-destructive method to predict the storage behaviour of apples.