Influence of carboxy methylcellulose, chitosan and beeswax coatings on cold storage life and quality of Kinnow mandarin fruit

Edible coatings are safer for human health and environment compared to synthetic waxes. The aim of this study was to assess the influence of different edible coatings on extending cold storage life and maintaining fruit quality of `Kinnow' mandarin (Citrus nobilis L. x Citrus deliciosa L.). Kinnow fruit coating treatments included 1.0, 1.5 and 2.0 g L-1 carboxy methylcellulose (CMC), 0.5, 1.0 and 1.5 g L-1 chitosan and 5, 10 and 15 g L-1 beeswax were contrasted to the uncoated (control) fruit. The coated and uncoated fruit were kept under cold storage conditions (5-7 degrees C and 90-95% RH) up to 75 days. The fruit were sampled following 30, 45, 60 and 75 days cold storage and evaluated for different quality parameters and scanning electron microscopy of the peel surface. The results indicate variability among the different polymer coatings for weight loss, spoilage loss, juice content, firmness, pectin content, the activity of pectin methylesterase and cellulase, soluble solids concentration (SSC), titratable acidity (TA), ascorbic acid content, total carotenoids content and organoleptic sensory attributes. Improved fruit gloss was observed in all coatings treatments, however, with the extension of the cold storage period, the fruit coated with chitosan and beeswax showed outward ruptures on the rind. Amongst all, the coatings tested, CMC (2.0 g L-1) coating was the most effective in maintaining various fruit quality parameters such as SSC, TA, vitamin C, sensory attributes and retarding the activities of cell wall degrading enzymes such as pectin methylesterase and cellulase up to 60 days in cold storage.