不同灭酶方式对黑青稞籽粒结构、营养组成及抗氧化性能的影响

为防止青稞氧化哈败，本研究采用微波、炒制及过热蒸汽三种常用的处理方式对黑青稞进行灭酶，考察达到相同的灭酶效果时，不同灭酶方式对黑青稞的微观结构、营养成分、酚类物质及抗氧化能力的影响。结果表明:三种处理后的黑青稞籽粒在表观上均出现不同程度的膨化与褐变，175 ℃下炒制20 min的颜色变化及等效半径最大，微波及过热蒸汽使籽粒膨化程度相似；灭酶处理后青稞在微观上出现出明显的缝隙，甚至孔隙。在微波和过热蒸汽处理组样品的维管束处出现较大的孔洞。青稞在灭酶处理后总酚（降低14.71%~20.52%）和总黄酮（降低11.39%~45.15%）含量均显著下降，其中经150 ℃炒制处理20 min的青稞样品的黄酮和酚类含量最低，而微波处理对总酚含量影响比其他两种处理更低，过热蒸汽处理对总黄酮含量的影响最小。除微波处理外，其他灭酶方式均使青稞的抗氧化能力上升，但不同灭酶处理后青稞抗氧化能力变化与总酚和总黄酮含量的变化趋势不完全一致，在灭酶率50%及60%的处理条件下，抗氧化能力排序均为过热蒸汽处理>炒制处理>微波处理。三种灭酶热处理在灭酶的同时均可有效提高青稞的营养品质，但综合评估，过热蒸汽处理是三种处理中的最优选择。

Effects of Different Methods of Inactivating Enzyme on Grain Structure,Nutrient Composition and Antioxidant Activity of Black Highland Barley

In order to prevent the oxidative rancidity of highland barley, three common treatment methods of microwave, roasting and superheated steam were used to inactivate the enzyme of black highland barley. Then the changes of microstructure, nutrient composition, phenolic compounds and antioxidant capacity before and after inactivation of enzymes treatment were evaluated when the same enzyme inactivation effect was achieved. The experimental results showed that different methods of inactivating enzyme resulted in different degrees of expansion and browning of highland barley. The color change and equivalent radius of highland barley roasted at 175 ℃ for 20 min was the largest, the equivalent radius of highland barley grain was similar after microwave and superheated steam treatment. By observing the electron microscope of highland barley treated with different methods of inactivating enzyme, it could be found that there were gaps and pores in the cross section of grain, and even large holes in vascular bundles. In addition, total phenols (decreased by 14.71%~20.52%) and total flavonoids (decreased by 11.39%~45.15%) decreased significantly after three treatments, and the content of flavonoids and phenols in highland barley roasted at 150 ℃ for 20 min was the lowest. While the effect of microwave treatment on the content of total phenols was lower than the other two treatments, and the effect of superheated steam treatment on the content of total flavonoids was the least. But DPPH free radical scavenging rate, ABTS+ scavenging rate and antioxidant activity increased except microwave treatment. However, the change trend of antioxidant capacity of highland barley after different enzyme inactivation treatments was not completely consistent with the change trend of total phenol and total flavonoids. Under the treatment conditions of enzyme inactivation rate of 50% and 60%, the antioxidant capacity of highland barley treated with superheated steam was the highest, followed by roasting treatment, and the antioxidant capacity of microwave treatment was the lowest. In summary, it can be concluded that the three treatments can be used to inactivate enzyme and can effectively improve the nutritional quality of highland barley. However, the comprehensive evaluation shows that superheated steam treatment is the best choice among the three treatments.