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

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 degrees 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 degrees 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 (A(420)/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.