Quality evaluation of aonla powder obtained by differentdrying techniques

The effect of different drying methods such as freeze, spray, solar, cabinet and sun drying on physico-chemical properties of aonla powder in terms of solubility in water, colour, ascorbic acid and polyphenols contents has been evaluated. Spray drying took least time for powder preparation (1 l/h) but yield was not satisfactory (6.3% only), while cabinet drying had best yield (14.6%) and moderate drying time (6 h). When solubility of powder in water was considered, which helped the powder to be used as ready-to-serve health drink as well as in encapsulated form in medicine, spray drying was found best (10 g/10 ml). Colour of spray and freeze dried powder was attractive white in comparison to brownish colour of powder by traditional techniques. Maximum contents of ascorbic acid and polyphenols were found in freeze dried powder (3593 mg/100 g and 23.6%) followed by spray dried (3282 mg/100g and 21.99%) and cabinet dried (3243 mg/100 g and 20.10%) powder. Though the contents of polyphenols did not differ significantly in five different drying techniques, ascorbic acid content varied considerably. In terms of quality parameters, the order of different drying methods is as follows: spray drying > freeze drying > cabinet drying > solar drying > sun drying