Infrared drying effects on the quality of jujube and process optimization using response surface methodology

Abstract

This study developed a specialized laboratory-scale apparatus utilizing infrared technology to optimize the infrared drying process and investigate water transfer dynamics and structural transformations during infrared radiation drying (IRD) of jujube. Key parameters, including rehydration ratio, color deviation, and Vitamin C (VC) retention rate, were assessed for Xinjiang gray jujube were assessed. Additionally. Comparative analyses were conducted to evaluate microstructural, physicochemical, and volatile component differences between IRD and hot air drying (HAD) methodologies. Response surface analysis was employed to optimize IRD parameters. The results identified optimal conditions as an infrared temperature of 55 °C, a loading capacity of 490 g, and an infrared radiation distance of 11 cm, resulting in a rehydration ratio of 1.75, a color deviation of 3.01, and a VC retention rate of 59.10g/100g. IRD demonstrated superior performance compared to HAD, with a 34.88g/100g improvement in VC retention rate and a 42.90g/100g reduction in drying time. Additionally, jujube dried using IRD exhibited a denser microstructure than those dried by HAD. These findings highlight the effectiveness of IRD in accelerating drying processes while maintaining high jujube quality, thereby providing a robust theoretical foundation for future jujube drying research.