真空冷冻与热风联合干燥对桑葚干品质的影响

Effect of freeze-hot air drying on the quality of dried mulberry

为提高桑葚干的品质,比较了真空冷冻干燥、热风干燥和真空冷冻联合热风干燥对桑葚干品质的影响,对干燥后桑葚干的色泽、硬度、脆性、复水比及总花色苷及单体酚类物质的保留量、DPPH·清除能力进行分析。结果表明,真空冷冻干燥的桑葚干品质最好,而较短时长(18~24 h)的真空冷冻干燥联合较高温度(85℃)的热风干燥能提高干燥效率,其总花色苷、绿原酸、芦丁的含量也显著高于热风干燥;桑葚中总酚、总花色苷、矢车菊素-3-葡萄糖苷、矢车菊素-3-芸香糖苷、槲皮素、绿原酸的含量与抗氧化能力具有显著的正相关性。

In order to improve the quality of dried mulberry, the effect of freeze drying, hot air drying and freeze-hot air drying on the quality of mulberry was investigated. The color, hardness, crispness, rehydration ratio, the content of total anthocyanins and individual phenolic compounds, and DPPH radical scavenging activity were determined. Results showed that the quality of freeze dried mulberry fruits was best. However, short time(18-24 h) freeze drying combined with high temperature(85℃) hot air drying could improve drying efficiency. The contents of total anthocyanins, chlorogenic acid and rutin in freeze-hot air drying mulberries were significantly higher than those in hot air drying fruits. Correlation analysis also showed that total phenolics, total anthocyanins, cyanidin-3-glucoside, cyanidin-3-rutinoside, quercetin, chlorogenic acid content had significant positive correlation with antioxidant capacity.