(1.华南农业大学 食品学院, 广东 广州 510640;2.广东省农业科学院 蚕业与农产品加工研究所/ 农业农村部功能食品重点实验室/广东省农产品加工重点实验室, 广东 广州 510610;3.仲恺农业工程学院, 广东 广州 510225)
(1.College of Food Science, South China Agricultural University, Guangzhou 510640, China;2.Sericulture and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences/ Key Laboratory of Functional Food, Ministry of Agriculture and Rural Affairs/Guangdong Key Laboratory of Agricultural Products Processing, Guangzhou 510610, China;3.Zhongkai College of Agricultural Engineering, Guangzhou 510225, China)
In order to provide theoretical support and technical guidance for improving the quality of dried food, the effects of osmosis and freezing pretreatment on the drying characteristics of blueberry were investigated. In this study, blueberries were treated with different combination modes of osmosis (trehalose, calcium chloride, sucrose) and freeze-thaw (liquid nitrogen -80℃, room temperature) before the same drying treatment (hot air, 30 h, 60 ℃), and the dehydration rate, water content, color, texture, total sugar content and antioxidant active substances were determined and compared. The results showed that different combination of osmosis and freeze-thaw pretreatment had a significant effect on the physical and chemical quality of blueberry. The freezing-thawing-osmotic-drying group was the best, and compared with the single osmotic group, the single freezing-thawing group, and the untreated group, the dehydration rate was increased by 5.55%, 6.39% and 36.91%, the hardness was enhanced by 8.59%, 39.80%, 909.00%, the retention rate of total sugar content was elevated by 1.10,1.44,2.70 times, and the antioxidant activity (total phenol, anthocyanin, oxygen radical absorbance capacity) was increased by more than 16%, respectively. In conclusion, freezing-thawing treatment could improve the osmotic influence on drying characteristics of blueberry, the combination of them had significant synergy on the enhancement of drying rate and drying quality.