Sequential‐combined solar energy assisted hot air and hot air‐assisted radio frequency drying to produce high‐quality dried whole apricots: An optimization study for process parameters

Abstract

A solar energy assisted hot air (SAAD) and its sequential combination with hot air-assisted radio frequency drying (HARFD) system was used to dry whole apricots. Sequentially combined drying conditions (pre-drying temperature (50–70°C), pre-drying time (300–1,140 min), distance between electrodes (77–85 mm), and radio frequency drying time (270–690 min)) were investigated and optimized using the Box–Behnken design for minimum browning and surface color and optimum texture and moisture content. Under optimum conditions of 63.5°C pre-drying temperature, 895 min pre-drying time, 77 mm distance between radio frequency electrodes, and 385 min radio frequency drying time; the moisture content, amount of browning products, total color change, and hardness were 22.31% ± 2.82%, 0.69 ± 0.03 (A420/g dry weight), 37.65 ± 2.23, and 1,293.46 ± 61.96 N, respectively. Sequential combination of SAAD with HARFD system provided high-quality whole apricots while reducing the processing time. Novelty impact statement Sequentially combined solar energy assisted hot air and hot air-assisted radio frequency drying system was used for the first time to dry whole apricots and process parameters were optimized to produce high-quality products using response surface methodology. The results showed that the applied sequential drying technique is promising to produce commercially marketable apricots in a short time with acceptable quality characteristics. Consequently, the sequentially combined drying system could be an alternative technology in industry.