The kinetics of nutritional quality changes during winter jujube slices drying process

Abstract

The purpose of this research is to investigate the kinetics of nutrient’s change (vitamin C, reducing sugar, and total acidity) of winter jujube slices that are submitted to drying at different temperatures (55, 60, 65, and 70°C) and air velocities (3, 6, and 9 m/s) during the air-impingement drying process. Results showed that the content of vitamin C and reducing sugar, and total acidity decreased with increasing drying time. Furthermore, analysis of variance indicated that the drying temperature, air velocity, and time had a significant effect on the loss of vitamin C and reducing sugar, and on total acidity (P < 0.05). Zero-order, first-order, and Weibull models were used to fit the experimental data, Weibull model was considered as the most suitable one for the degradation kinetics of vitamin C and reducing sugar, and change of total acidity in samples dried at different temperatures and air velocities. According to the Arrhenius formula, the activation energy of vitamin C, reducing sugar, and total acidity change kinetics were 63.78, 36.48, and 153.51 kJ/mol, respectively. This research can provide some references for enhancing dried product quality in the jujube drying industry.