等离子体处理对小米内源酶活性及其品质的影响

Effects of Plasma Treatment on the Endogenous Enzyme Activity and Quality of Foxtail Millet

摘要:

该研究以陕西米脂小米为研究对象，考察了介质阻挡放电-空气等离子体处理对小米脂氧合酶与脂肪酶的活性、色度、总黄色素等的影响。研究发现等离子体对小米内源酶活性具有显著的钝化作用，例如电压为25 kV条件下处理12 min时，小米脂氧合酶与脂肪酶相对活性分别降低至31.15%与25.22%。另外，经15 kV和25 kV处理12 min后，小米色度没有显著变化（p>0.05）；当电压升至35 kV且处理同样时间后，小米L值从58.27升高至62.68，而b*值分别从43.06降低至38.74，变化显著（p<0.05），该结果与小米总黄色素含量的变化一致，说明电压过高时等离子体处理对小米色素成分具有一定的破坏作用。进一步研究了小米DPPH清除自由基能力、丙二醛产生量与小米形态的变化，结果显示经等离子体处理后小米在形态、DPPH清除自由基能力与丙二醛产生方面无明显变化（p>0.05）。结果表明等离子体处理可钝化小米中的脂氧合酶与脂肪酶，并一定程度维持小米的外观品质。该研究为运用该技术延缓小米陈化方面提供了一定的理论依据。

Abstract:

The effects of dielectric barrier discharge-atmospheric cold plasma (DBD-ACP) on the lipoxygenase and lipase activities and the physiochemical properties (chromaticity, total yellow pigment content, and DPPH free radical scavenging capacity) of foxtail millet (Mizhi, Shaanxi) were investigated. DBD-ACP was found to have a significant inactivation effect on the activities of endogenous enzymes in foxtail millet (p<0.05). For example, treatment at a voltage of 25 kV for 12 min decreased the relative activities of lipoxygenase and lipase to 31.15% and 25.22%, respectively. The chromaticity indicators (L and b*) of millet did not change significantly (p>0.05) after DBD-ACP treatment under 15 kV and 25 kV for 12 min; whereas increasing the voltage to 35 kV under the same treatment time led to a significant increase in the L value from 58.27 to 62.68, and a decrease in the b* value from 43.06 to 38.74 (p<0.05). These results were consistent with the changes in the total yellow pigment content of foxtail millet, indicating that the DBD-ACP treatment had a certain destructive effect on the pigment components in millet at excessively high voltages. The changes in the DPPH scavenging ability, malondialdehyde (MDA) production, and morphology of foxtail millet were further studied. The results showed that there were no significant changes in DPPH scavenging ability, MDA production, and morphology of foxtail millet after DBD-ACP treatment (p>0.05). These results suggest that DBD-ACP can be used for the inactivation of lipoxygenase and lipase, while also maintaining the appearance quality of foxtail millet to some extent. This study provides a theoretical basis for the application of DBD-ACP technology in the inactivation of endogenous enzymes to delay the aging of millet and stabilize its appearance quality.