Effects of Different Drying Methods on the Quality, Nutritional Components, and In Vitro Bioaccessibility of...

This study systematically compared the effects of vacuum freeze drying (FD), vacuum microwave drying (MVD), hot air drying (HAD), and their combined drying methods (MVD-FD, HAD-FD, MVD-HAD) on the physical properties, nutritional components, and bioaccessibility of active compounds in kiwifruit. Two typical kiwifruit varieties, Zespri Green and Zespri SunGold, were used as raw materials. The results indicated that both FD and MVD-FD were effective in preserving kiwifruit color, while the MVD-FD samples additionally possessed moderate hardness and favorable textural properties. The FD samples displayed a uniform porous structure, while the MVD-FD samples showed variably compressed pores. In terms of nutrient retention, the FD and MVD-FD methods yielded the highest contents of total acid, total sugar, polyphenols, ascorbic acid, lutein, and zeaxanthin. In vitro digestion demonstrated that MVD-FD significantly enhanced the bioaccessibility of active compounds compared to FD, including polyphenols, ascorbic acid, lutein, and zeaxanthin. In conclusion, MVD-FD is considered a suitable method for producing high-quality kiwifruit dried products with enhanced nutritional value.