Influence of pre-treatment on drying kinetics and chemical composition of pea processing waste

Abstract

This study investigated the effects of different treatments such as hot water blanching and potassium metabisulphite (KMS) treatment after blanching, along with various air-drying temperatures on pea processing waste. The drying process was conducted using a laboratory tray dryer at temperatures of 50 °C, 60 °C, and 70 °C, as well as their combinations, for various durations. The equilibrium moisture content decreased with increasing drying air temperature owing to higher moisture diffusivity. The Logarithmic model showed the best fit to the drying data, exhibiting R² values ranging from 0.979 to 0.999. Chemical analysis of proximate composition, bioactive composition, chlorophyll content, and color (L*, a*, b*) was conducted to determine the optimal time-temperature combination. The results indicate that pea pods treated with KMS and dried at 60 °C for 5 h resulted in the highest retention of polyphenols (9%), ascorbic acid (20%), and chlorophyll content (17%) compared to blanched samples. Moreover, antioxidant content increased by 37–40% in pre-treated and dried pea pod powder relative to fresh pea pod. Additionally, pre-treatment process effectively preserved the color of pea pods, making it a desirable ingredient for various food products. This study contributes valuable insights into the optimization of pea processing waste utilization in the food industry.