Effects of ultrasound–calcium chloride pretreatment and microwave power level on quality characteristics of banana crisps dried with belt conveyor combined microwave–hot air/microwave puffing

Dried banana crisps produced by a belt conveyor combined with microwave-assisted hot air drying/microwave puffing (HAMW/MW-Puffing) exhibit substantial surface browning. To improve crisp quality, we tested various pretreatments prior to the HAMW/MW-Puffing drying process on banana slices (2.5 mm): distilled water (DW), calcium chloride (CA), ultrasound (US), or a combined method (USCA). Except for DW, all pretreatments significantly reduced the brown coloration, increased the volume ratio, and decreased the hardness of dried crisps. The USCA pretreatment coupled with 200 W microwave power resulted in the highest volume ratio (75.0%) and the lowest hardness (19.6 N). Increasing the microwave power yielded more browning, a harder texture, shorter drying time, and lower specific energy consumption (SEC). To balance product quality and SEC, USCA pretreatment at 300 W microwave power is recommended as the condition with the highest composite score under the evaluated criteria. Nevertheless, the overall preference score of USCA-treated samples was lower than that of the commercial product.