不同干燥方式对香菜品质及自由基清除能力的影响

Effects of Different Drying Methods on Quality and Free Radical Scavenging Ability of Coriander

目的:为获得一种能最大程度保留香菜原有品质,且经济高效的香菜干燥方法。方法:对香菜分别进行热风干燥、微波干燥、热风-微波联合干燥和微波-热风联合干燥处理(联合干燥的水分含量转换点均为65%),分别测定干制后香菜的色度、复水比、还原糖、蛋白质、维生素C、总黄酮含量以及羟基自由基清除能力,综合评价不同干燥方式对香菜品质的影响。结果:热风干燥、微波干燥、热风-微波联合干燥和微波-热风联合干燥的香菜干制品,色度变化:热风-微波干燥>微波干燥>热风干燥>微波-热风干燥;复水比分别为4.35,4.92,4.97,5.15;还原糖含量分别为4.15,3.98,4.27,5.21 g/100 g;水溶性蛋白含量分别为1.05,1.19,1.51,1.26 mg/mL;维生素C含量分别为3.27,4.54,3.36,3.26 mg/100 g;总黄酮含量分别为47.06,50.54,49.15,54.81 mg/kg;羟自由基清除率分别为18.9,21.7,19.7,24.8 U/mg prot。综上可知,不同干燥方式对香菜色度、复水比和营养指标的影响:热风干燥的香菜复水比增幅最小,微波-热风干燥的香菜色度变化最小,具有最大的复水比,香菜中保留的还原糖和总黄酮含量最高,羟自由基清除率最高。热风-微波联合干燥的香菜中水溶性蛋白保留量最高,维生素C的保留量仅次于微波-热风干燥。热风干燥的香菜复水比最小,水溶性蛋白、维生素C和总黄酮的保留量及羟自由基清除率最低。结论:综合4种干燥方式的结果,联合干燥的营养成分指标高于单一干燥,而微波-热风干燥方式效果最好,不仅能缩短单一热风干燥所需要的时间,而且能减少微波对香菜营养物质的破坏,可以在保证香菜质量的前提下,节约时间,降低能耗。

Objective:To obtain an economical and efficient drying method of coriander which can retain the original quality of coriander to the greatest extent.Method:Coriander is treated with hot air drying,microwave drying,hot air-microwave combined drying and microwave-hot air combined drying(the moisture content conversion point of combined drying is 65%).The color,rehydration ratio,the content of reducing sugar,protein,vitamin C,total flavonoids and hydroxyl radical scavenging ability of coriander are determined respectively.The effects of different drying methods on the quality of coriander are evaluated comprehensively.Results:The color change of the dried coriander products by hot air drying,microwave drying,hot air-microwave combined drying and microwave-hot air combined drying is hot air-microwave drying>microwave drying>hot air drying>microwave-hot air drying;the rehydration ratios are 4.35,4.92,4.97,5.15 respectively;the reducing sugar content is 4.15, 3.98, 4.27, 5.21 g/100 g respectively;the water-soluble protein content is 1.05, 1.19 , 1.51, 1.26 mg/mL;the vitamin C content is 3.27, 4.54, 3.36 , 3.26 mg/100 g respectively;the content of total flavonoids is 47.06, 50.54, 49.15, 54.81 mg/kg respectively;the hydroxyl rad ical scavenging rates are 18.9, 21.7, 19.7, 24.8 U/mg prot respectively. In summary, the effects of different drying methods on the color, rehydration ratio and nutritional indexes of coriander are: the increase of rehydration ratio of coriander by hot air drying is the smallest, the color change of coriander by microwave-hot air drying is the smallest, with the largest rehydration ratio, the content of reducing sugar and total flavonoids retained in coriander is the highest, and the hydroxyl radical scavenging rate is the highest. The retention amount of water-soluble protein in coriander by hot air-microwave drying is the highest, and the retention amount of vitamin C is the second only to microwave-hot air drying.Coriander by hot air drying has the smallest rehydration ratio, the lowest retention amount of water-soluble protein, vitamin C and total flavonoids and the lowest hydroxyl radical scavenging rate. Conclusion: Combining the results of the four drying methods, the nutritional composition indexes of combined drying are higher than those of single drying, and microwave-hot air drying has the best effect, which can not only shorten the time needed for single hot air drying, but also reduce the damage of microwave to coriander nutrients. It can save time and reduce energy consumption on the premise of ensuring the quality of coriander.