干制方式对紫淮山全粉的物理特性及其抗氧化能力的影响

Effect of Drying Methods on Physical Properties and Antioxidant Capabilities of Purple Yam Flour

采用热风干燥,喷雾干燥,真空冷冻干燥和喷雾冷冻干燥对紫淮山进行干燥制粉,研究不同干燥方式对紫淮山全粉的水溶性指数、碘蓝值、色差、总酚、花色苷、及抗氧化能力的影响。结果表明,4种干燥方式所制得产品在水溶性指数、碘蓝值、色差等方面具有显著性差异(p<0.05)。喷雾干燥法和喷雾冷冻干燥法制取的紫淮山全粉比热风干制和真空冷冻干制所得产品具有更高的水溶性指数和碘蓝值,热风干燥制得紫淮山全粉颜色褐变最为严重,喷雾冷冻干燥的紫淮山全粉的花色苷和总酚含量最高,分别达到14.17 mg/100 g和288.39 mg/100 g,其DPPH自由基和OH自由基清除率也最高。根据相关性分析得知紫淮山全粉中花色苷和总酚含量均与清除自由基能力存在显著的正相关关系(p<0.01)。喷雾冷冻干燥和真空冷冻干燥所制全粉与喷雾干燥和热风干燥制粉比较,总酚、花色苷等抗氧化物质保留率高,具有更好的品质。

Hot air drying,spray drying,vacuum freeze drying and spray freeze drying were used in drying purple yam and producing flour.The effects of 4 different drying methods on physical properties including water solubility index,starch-iodine value,numerical total color difference,antioxidant capabilities and total phenolics content,anthocyanins content of the whole flour were studied.The results indicated that there were significant differences in water solubility index,starch-iodine value and numerical total color difference between the aforementioned 4 drying methods(p<0.05).The flour produced by spray drying and spray freeze drying had higher water solubility index and starch-iodine value than those by hot air drying and vacuum freeze drying.Serious browning was took place during hot air drying procedure.The contents of anthocyanins and total phenolics in the flour produced by spray-freeze drying method was 14.17 mg/100 g,288.39 mg/100 g respectively,which was highest and had strongest DPPH and OH free radical scavenging capability in which produced by the aforementioned methods.Meanwhile,the anthocyanin and total phenolics content in purple yam flour were in positive correlation with free radical scavenging capability(p<0.01).Spray freeze-drying and vacuum freeze drying benefited the quality of purple yam flour with higher contents of total phenolics and anthocyanins.