Influence of Osmotic Dehydration and Method of Drying on the Quality of Aonla Fruit

Abstract

Osmotic dehydration of aonla fruit was carried out to determine the Influence of osmotic solution and method of drying on the quality of aonla fruit. The destined aonla fruits with and without blanching were immersed in the mixture of salt and sugar solution. The salt concentration of the osmotic solution was kept constant (100 g) and the sugar concentrations were varied to bring the concentrations to 35, 45 and 55°B maintaining a fruit to syrup ratio of 1:3 by weight. The observations were recorded to study the influence of osmotic solution and time on water loss and solid gain. The subsequent drying was carried in hot air and vacuum driers at 50±5°C to a safe storage moisture level of 0.35 kg of water per kg of dry matter. The results showed the maximum water loss of 48.55% recorded for blanched fruit osmosed at 55°B and the minimum (27.61%) in unblanched fruit osmosed at 35°B. The solid gain was observed to be maximum (23.4%) in the blanched fruit compared to unblanched fruit (9.94%) at respective concentrations. Subsequent drying showed that drying was in falling rate and time taken was higher for untreated compared to treated. The blanching and method of drying had a significant effect on the quality of fruit. Colour was found better (Bright greenish-yellow) in blanched vacuum dried fruit followed by unblanched vacuum dried. The maximum amount of ascorbic acid was noticed in the freshly vacuum dried fruit (1780.2 mg/100 g) compared to osmosed fruits (534.8 to 1369.6 mg/100 g). Total sugar was found maximum in the osmosed vacuum dried fruit (82.2%) fruit compared to fresh once (24.6%) but the drying method had no significant effect on the retention of sugars.  The mean scores for sensory showed that overall acceptability was higher for blanched vacuum dried fruit followed by unblanched vacuum dried fruits.