Ultrasonication-assisted polyol-osmosed persimmon candies: effect of ultrasonication and drying techniques on product quality†

Persimmon is a widely cultivated fruit known for its sweet and rich flavour and nutrition. However, this climacteric seasonal fruit is underutilized and scarcely processed. Persimmon has good potential for conversion into dehydrated fruit candies. To override the high calorific value associated with sugar-osmosed fruit candies, xylitol and erythritol were used as osmotic agents. The long processing duration for osmotic dehydration (OD) was aimed to be shortened through ultrasonication (US) for enhancing the mass transfer rate and product quality. The moisture ratio, weight loss, solid gain with osmotic agents, sucrose, erythritol and xylitol at 30–60% concentrations and 50–70 °C were modelled using non-linear models. The logistic model was found to be most appropriate to describe the kinetics of the OD process. Rates of OD varied in the following order: xylitol > erythritol > sucrose. US significantly affected the rate of polyol-osmosed dehydration and greatly improved textural and sensory qualities. To offer convenience attribute to the fruit, the osmosed fruits were converted into dry candies using a tray dryer and infra-red dryer and compared for nutritional, textural and sensory attributes. SEM images and lower bite force confirmed that US-OD followed by IR drying yielded much better quality of candies than conventional methods for all sweeteners. The highest carotenoid retention, L* values, and ascorbic acid retention were recorded for persimmon candies osmosed in 60% erythritol. This study provides valuable insights into the application of ultrasonication and polyols for the effective utilization of nutritious persimmon and caters to the needs of faster processing times, higher nutrient retention and low calorific load in fruit candies.