不同干燥方法对核桃品质及不饱和脂肪酸稳定性的影响

为考察不同干燥方法对货架期核桃坚果营养品质的影响,以恒温热风干燥方法为对照,采用变温热风干燥和远红外干燥方法对采后鲜核桃进行干燥,室温(24℃)存放,分析比较核桃不饱和脂肪酸及品质稳定性。结果表明,远红外干燥至大约4%的水分含量所需时间为对照组的一半。贮藏6个月后,变温热风干燥组核桃油酸、亚油酸和亚麻酸分别降低了9.59%,10.58%和12.71%;远红外干燥组分别降低了7.49%,7.34%和6.77%;对照组分别降低了14.44%,11.79%和15.50%。3组核桃的过氧化值和羰基价依次分别是0.88,2.94,0.60,2.08,0.98,3.52 meq/kg。远红外干燥不仅能缩短干燥时间,而且能延缓核桃的氧化酸败,更好的保持核桃的品质。

Effects of Different Drying Methods on Quality of Walnuts and Stability of Unsaturated Fatty Acids

In order to investigate effects of different drying methods on the nutritional quality of walnuts, the fresh walnuts were dried by the changeable-temperature hot air drying and far-infrared radiation drying methods and the conventional hot air drying method was used as the control. The nutrition functional component and quality stability of walnuts stored at room temperature were compared. The results showed that the far-infrared drying method could half decrease the dry time compared with the control method when the water content of walnuts was 4%. After 6-month storage, the contents of oleic acid, linoleic acid, and linolenic acid of walnuts dried by the changeable-temperature hot air method were reduced 9.59%, 10.58%, and 12.71%, respectively. As for walnuts dried with the far-infrared radiation method, they were reduced 7.49%, 7.34%, and 6.77%, respectively and the contents of oleic acid, linoleic acid, and linolenic acid of walnuts in the control group were reduced 14.44%, 11.79%, and 15.50%, respectively. The peroxide values of walnuts treated by the changeable-temperature hot air method, far-infrared radiation method, and the conventional hot air drying method were 0.88,2.94, and 0.60meq/kg, respectively while the carbonyl values of walnuts treated by the three methods were 2.08,0.98, and 3.52meq/kg, respectively. Compared with the conventional hot air drying method, the far infrared-assisted hot air drying method not only reduced the drying time but also retarded the development of oxidative rancidity, and improved the quality of walnuts.