The impact of refractance window drying on the physicochemical properties and bioactive compounds of malbhog banana slice and pulp

Abstract

The present study aimed to design and evaluate the effect of different drying methods, viz. refractance window drying (RWD), hot air drying (HD), freeze-drying (FD) and vacuum drying (VD) on qualitative properties such as crude fiber, ash content, total phenolic content (TPC), total flavonoid content (TFC), Antioxidant activity (AA), FTIR spectra, color and texture of banana slice and pulp fractions. In this experimental investigation, malbhog variety banana was selected. The average drying time of the banana sample in RWD, HD, FD and VD was found as 760 min, 930 min, 1125 min and 975 min at drying temperatures of 60 °C, 60 °C, -40 °C and 60 °C respectively. A qualitative evaluation revealed that the anti-oxidant, phenolic and flavonoid content were rich in freeze-dried and RWD-dried samples compared to that of hot air-dried and vacuum-dried samples. The color retention was also significant in FD and RWD samples. Total phenolic content (TPC) of 441mg GAE/100 gm and crude fiber content of 1.92% was found to be higher in RWD banana samples in comparison to other drying methods. Antibrowning agents coated dried banana samples viz. slice and pulp has shown less color change and nutrient retention as compared to untreated dried banana samples. The highest nutrient retention in less drying time was found in RWD banana samples.