Effect of radio frequency combined oven pretreatment on the drying characteristics and quality of sweet potatoes

Abstract

Dried sweet potato products with a soft texture and sweet flavor are very popular among consumers. Compared with the raw material, preserved sweet potato after pre-cooking has more benefits for the human body. Radio frequency combined with oven (RF-O) baking has been considered as an efficient method of cooking sweet potatoes that takes short time and maintains good product quality. To investigate the potential of RF-O cooking as a pretreatment method before drying sweet potatoes, the impact of RF-O cooking on the characteristics of hot air drying, hot air assisted RF drying, and RF combined with hot air drying was explored. After RF-O pretreatment, the trends of hot air assisted RF drying were similar to those of RF combined with hot air drying for samples. Compared to the hot air drying (210 min), hot air assisted RF drying (180 min) and RF combined hot air drying (200 min) showed a small advantage in drying time. All three drying treatments could provide high quality potatoes with similar color (∆E values of 9.81–11.12), texture (hardness values of 2360.67–3345.07 gf) and soluble solid content (20.72 % - 21.81 %). Therefore, RF-O cooking could be used as a short pretreatment for sweet potatoes before drying by providing guidance for the drying process in the food industry.