Quality characteristics and moisture sorption isotherm of three varieties of dried sweet potato manufactured by hot air semi-drying followed by hot-pressing

This study compared the quality and moisture sorption properties of dried sweet potato prepared from three varieties (two yellow types and one purple type). Semi-dried sweet potato was subjected to a hot-pressing, which led to a final moisture content of 0.14-0.22 kg/kg solid (dry weight basis). The textural properties of the dried product depended on the sugar content of raw materials. In addition, the sugar content also influenced the MSI properties of the dried product. Based on the mathematical models, the GAB equation was revealed as the best model to explain the MSI properties of dried sweet potato. Among the varieties, Annou-beni (AB) showed the highest sugar content and would be the best variety from a taste point of view. Beni-haruka (BH) showed similar qualities to AB, while the less sugar content of this variety reflected that curing was essential for BH to improve consumers' preference. Shin-jami (SJ) had a weak point in sweetness since it possessed the lowest sugar content. However, the low sugar content of SJ with an attractive color trait induced an acceptable crispy texture and made the product healthier, and SJ could serve as a good sweet potato variety to make dried snack products.