Effect of different drying methods on the quality and microstructure of fresh jujube crisp slices

This study investigated the effects of different drying methods, including hot-air drying (HD), freeze drying (FD), and pressure-differential puffing drying (PPD), on the quality and microstructure of fresh jujube crisp slices. Our data confirmed that PPD has the best effect, followed by FD and HD. Crisps dried using FD had good color and the best rehydration rate, shrinkage volume rate, and apparent density. The color, rehydration, and hardness of fragile chips by PPD and FD were similar; jujube slice volume shrinkage and density increase were due to water evaporation during drying. The bioavailability and microstructure of PPD was the best. Polysaccharide and total phenol bioavailability was the highest in PPD samples and remained stable, with clear porous structure and a smaller folding structure, indicating that PPD maintains the porous cell structure. Thus, PPD provides high quality fresh jujube crisp slice products due to uniform honeycomb network and less collapsed structure. Practical applications Jujube is a fruit grown in China. This study provides technical information and theoretical basis for the production of puffed dry food, which is widely used in food production. First, the crisps obtained can be directly graded, packaged, sold, and transformed into green snack food; these techniques can be applied to other fruits, such as cantaloupe, apricot, and carrot. Second, dried fruits and vegetables were directly processed into ultra-micro nutrient powder, which retains its flavor to a large extent. Furthermore, the dried powder may be used as auxiliary materials or seasoning in the processing of other foods to improve the color and flavor of the product. Processing fresh jujube into crisps can widen its industrial applications and add value to its products.