Effects of Different Drying Methods on Drying Kinetic Models, Physicochemical Properties, and Drying Quality Composite Scores of Rosa roxburghii Tratt (Fruit)

Abstract

The aim of this study is to investigate efficient, cost-effective, and high-quality drying technologies for Rosa roxburghii Tratt. Five drying methods—hot air drying (HAD), microwave drying (MD), vacuum drying (VD), microwave vacuum drying (MVD), and freeze vacuum drying (FVD), were employed to dry Rosa roxburghii Tratt. The study focused on evaluating drying characteristics, colors, texture and structure, and microstructure, as well as the content of active ingredients and antioxidant activity of Rosa roxburghii Tratt. The results of drying kinetics indicated that the Wang and Singh model was the most suitable for FVD, while the Page model was optimal for the other four drying methods. Rosa roxburghii Tratt subjected to HAD exhibited the highest energy consumption per unit but the lowest ΔE and the highest TFC. The microstructure of Rosa roxburghii Tratt under different drying methods was analyzed. Rosa roxburghii Tratt dried using MD experienced serious cell rupture, resulting in a large loss of active ingredients and the worst antioxidant ability, but it had the fastest drying rate. On the other hand, Rosa roxburghii Tratt dried under VD had the microstructure with the least pore space, leading to slower drying speed and the highest total polyphenol content. Rosa roxburghii Tratt dried using MVD had the least hardness and chewiness, with slightly better ΔE and active ingredient content compared to MD. FVD Rosa roxburghii Tratt took the longest time to dry, with the greatest ΔE difference, hardness, and chewiness, but it had the highest Vitamin C content and the most powerful antioxidant ability. Principal component analysis (PCA)–entropy weighting method was used to provide comprehensive scores for the different drying methods, with FVD, HAD, VD, MVD, and MD were 0.8107, 0.7037, 0.4499, 0.2746, and 0.0586 respectively. Through comprehensive analysis, we demonstrated that the quality of Rosa roxburghii Tratt obtained via FVD and HAD is satisfactory. Additionally, HAD is characterized by its economic efficiency and convenience, providing valuable insights for the industrial production of Rosa roxburghii Tratt drying.