Study on raisin quality and storability affected by coating of guar gum and glycerol combinations

Abstract

Raisin is an important agriculture product which turns sticky and hard due to syrup exudation and loss of water during storage. Surface coating provides protective layer to the product and it is found to reduce losses and extended life. Present study was carried out at ICAR-National Research Centre of Grapes, Pune during 2018. Manjari Kishmish raisins having 15 per cent moisture were utilized to study influence of guar gum coating on quality and storage. Different combinations of guar gum with glycerol were applied for 2 minutes on raisins and compared with control. The coated raisins were stored at 25±2 °C for a period of 40 days. Physiological loss in weight (PLW), antioxidant activities (DPPH assay) and colour intensity were noted at interval of 10 days. Minimum PLW (1.13%) was recorded in T3 followed by T2 on 40th day of storage. T3 was registered with better antioxidant activities (38.12%). Minimum color intensity (0.14%) was also observed in T3 on 40th day of storage. Poor condition of raisins were recorded in control. On the basis of data collected during study it is concluded that coating of raisins with 0.25% guar gum with 40 per cent glycerol extended storage life and maintained good colour with higher antioxidant activities.