Quality evaluation of spray-dried powder prepared from aonla juice blended with pigment-rich vegetable juice during storage

Abstract

Aonla is a rich source of natural ascorbic acid and polyphenols, while vegetables are rich source of pigments. The aim of the present study was to provide better nutritional quality of spray-dried aonla powder by enriching it with carotenes and anthocyanins. Spray-dried powder was prepared either from pure aonla juice or by blending it with 10 per cent carrot or/and beet juice using a laboratory model spray dryer. Powder samples were stored in food grade laminated aluminium foil pouches up to 6 months under ambient conditions. Ascorbic acid (3700 mg/100 g) and polyphenols (19.74%) were found highest in pure aonla powder. Blended powder of aonla and beet showed a significant increase in anthocyanins content from 0.47 to 14.25 mg/100 g, while that of aonla and carrot showed an increase in total carotenoids from 0.53 to 6.92 mg/100 g. The contents of ascorbic acid, total carotenoids and anthocyanins in powder prepared from blended juice of aonla, carrot and beet were observed to be 3478, 6.69 and 12.97 mg/100 g, respectively. During storage, an increase in anthocyanins and non-enzymatic browning were noticed in all spray-dried powder samples whereas, the contents of ascorbic acid and total carotenoids decreased. The amount of ascorbic acid was found highest (2442 mg/100 g) in pure aonla powder followed by powder obtained from mixed aonla and carrot juice (2193 mg/100 g) after 6 months of storage. The content of polyphenols did not change significantly during storage in any of the powder samples. The critical and danger points in terms of equilibrium moisture content (EMC) for spray-dried aonla powder were observed to be 1.96 and 1.86 per cent, respectively. At 50% relative humidity (RH) colour of the powder changed from white to brown and lump formation started. The liquefaction of powder started and mould growth appeared at 80% RH. Carotene and anthocyanins enriched spray-dried aonla powder could be prepared and stored in hermetically sealed packaging up to 6 months under ambient conditions without much deterioration in nutritional quality.