Evaluation of nutritional quality of aonla during freeze-drying

Freeze-drying of aonla for achieving maximum retention of nutrients was attempted in the present study. Three commercial varieties of aonla, viz. Krishna, Chakaiya and NA-7, were freeze-dried in the form of shreds, pieces (supari) and segments. The samples were first pre-freezed at –18°C in a deep freezer and then subjected to drying in a freeze drier. The temperature of the drying trays was maintained at 30°C, while the temperature of the chamber was kept at –55°C. The drying time of the shreds was least (3 h to 3 h 15 min), while segments took maximum time (9 h to 9 h 30 min). All the varieties behaved similarly during freeze-drying. The quality in terms of moisture, TSS, acidity, ascorbic acid and polyphenols was evaluated in fresh fruits as well as in freeze-dried samples at zero time and after 90 days of storage under ambient conditions. A slight decrease in the nutrients was noticed during freeze-drying of aonla. The retention of ascorbic acid and polyphenols was maximum in freezedried segments, in all the varieties tried, after 90 days of storage. Krishna was found to be least suitable for freezedrying among the varieties tested.