干燥方式对紫苏叶品质的影响

Effects of Drying Methods on Quality of Perilla frutescens Leaves

为评价不同干燥方式对紫苏叶品质的影响,采用热泵干燥(heat pump drying,HPD)、远红外干燥(far-infrared drying,FIRD)、真空冷冻干燥(vacuum freeze drying,VFD)、热风干燥(hot air drying,HAD)4种干燥方式对紫苏叶进行处理,测定其基本营养成分含量、活性成分含量及抗氧化能力,并利用隶属函数法进行综合评价,采用顶空固相微萃取-气质联用技术鉴定其挥发性物质。结果表明,VFD处理的紫苏叶中蛋白质、粗脂肪、黄酮、多酚、迷迭香酸含量最高,色差值最小,DPPH、ABTS~+自由基清除能力最强;HPD处理的紫苏叶中还原糖含量最高;经4种干燥方式处理后,紫苏叶中挥发性物质的种类与相对含量都有不同程度的增减,烯烃类和醛类为主要挥发性物质。综合评价表明,VFD处理的紫苏叶品质优于其他干燥处理,但能耗较高;HPD处理的紫苏叶品质优于HAD和FIRD,是紫苏叶干燥处理的一种较好选择。

To evaluate the effects of different drying methods on the quality of Perilla frutescens leaves,four drying methods,namely heat pump drying(HPD),far-infrared drying(FIRD),vacuum freeze drying(VFD)and hot air drying(HAD),are used to treat Perilla frutescens leaves.The content of basic nutritional components,the content of active components and antioxidant capacity are measured,and comprehensive evaluation is conducted using the membership function method.The volatile substances are identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry.The results show that the Perilla frutescens leaves treated with VFD have the highest content of proteins,crude fat,flavonoids,polyphenols and rosmarinic acid,the smallest color difference value,and the strongest DPPH and ABTS+free radical scavenging capacity.The Perilla frutescens leaves treated with HPD have the highest content of reducing sugar.After being treated with the four drying methods,the types and relative content of volatile substances of Perilla frutescens leaves have varying degrees of increase or decrease,with alkenes and aldehydes as the main volatile substances.The comprehensive evaluation indicates that the quality of Perilla frutescens leaves treated with VFD is superior to that of other drying methods,but the energy consumption is higher.The quality of Perilla frutescens leaves treated with HPD is better than that of HAD and FIRD,making HPD a better choice for the drying treatment of Perilla frutescens leaves.