Effect of biological enzyme pretreatment on the kinetics, microstructure, and quality of vacuum drying of wolfberry
Tiejian Yuan, Da Zhang, Xiaoqiong Li, Peng Xu, Zhentao Zhang, Yu Yang, Junling Yang, Yan He, Ramadan ElGamal
Abstract
To explore the feasibility of enzyme pretreatment for optimizing the drying process of wolfberry, enzyme dewaxing pretreatment was used in this study firstly to enhance the vacuum drying rate and quality of wolfberry. This study investigated the effects of four single enzymes and a mixture of enzymes for dewaxing on the color, polysaccharides, flavonoids, total phenolics, and antioxidant capacity of wolfberry vacuum drying treatment. Compared to the untreated samples, the mixed enzyme treatment group exhibited a 57.29% reduction in drying time and a decrease in activation energy from 27.48 kJ/mol to 25.56 kJ/mol. Additionally, it demonstrated the highest rehydration rate, polysaccharide content, total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical scavenging activity, as well as the smallest color difference and water activity. Scanning electron microscopy revealed that these characteristics originate from the most pore microstructure. By selectively breaking down the wax layer, higher connectivity pores are formed to facilitate water migration and evaporation. The optimal process for enzyme dewaxing pretreatment is Pectinase + Cutinase, with a temperature of 50 °C and a soaking time of 30 min. • The Optimal enzyme dewaxing pretreatment: Pectinase + Cutinase at 50 °C for 30 min. • The mixed enzyme pretreatment could shorten the drying time by 57.29%. • Mixed enzyme treatment group exhibits superior quality attributes. • Enzyme pretreatment selectively disrupts the wax layer. • Enzyme pretreatment creates more pores, promoting water migration and evaporation.