常温真空包装对保持小米储藏品质的影响

为了探究一种有效的小米储藏方法,以晋谷42号小米为试材,采用0.08 mm厚尼龙(polyamide,PA)复合聚乙烯(polyethylene,PE)袋包装,常温((20±2)℃)环境中储藏,研究小米在常规、常规密闭和真空包装储藏120 d品质指标的变化规律。结果表明:相对于常规包装,真空包装储藏有效降低脂肪氧合酶的活性(P<0.05),延缓小米脂质的氧化分解(P<0.05),抑制小米游离脂肪酸含量的升高(P<0.05),较好地保持了小米的水分(P<0.05),延缓了小米黄色素的损耗(P<0.05),较好地保持了小米的亮度(P<0.05)、米黄色(P<0.05)以及弹性(P<0.05)和黏附性(P<0.05);常规密闭包装具有一定的储藏效果,但不及真空包装。因此,常温下真空包装储藏可以有效延缓小米的陈化,保持小米的储藏品质。研究结果为小米储藏,提升小米储藏品质提供了理论依据和技术支持。

Effect of vacuum packaging at room temperature on maintaining storage quality of millet

Millet is the product of the husk removal of Foxtail Millet, one of the oldest crops in the world, which originated in the Yellow River basin, and now widely planted in the northern region of China. Millet serves as a kind of common coarse cereals, and natural health-care product, which can be used both as food and medicine,attracting a large amount of consumers.However, the storage of millet become challenge because the millet easy to change without the protection of shell. In the storage process, the millet can be disturbed by many parameters, including temperature, humidity, oxygen and microorganism,to deteriorate product quality, such as aging, fever, mildew, insect damage, etc. Therefore, it is necessary to explore the effective methods forthe millet storage and preservation, in order to ensure the stability of millet quality and food security.This study aims to investigate some effects of vacuum packaging on the storage quality of the millet. In this experiment, Jingu42 millet was used as the test material. The test millet was packed in 0.08 mm thick polyamidecomposite polyethylene bags,each containing 400 g. Samples were randomly divided into three groups. The first group of millet was sealed with vacuum(absolute vacuum is 0.01 MPa) for storage. The second group of millet was conventional closed storage. The third group of millet was conventional storage as the control condition. All samples were stored at room temperature. Taking a bag of millet every 30 days to measure the relevant indicators, such as the crude fat, free fatty acid, lipoxygenase(LOX) activity, water content, yellow pigment, color difference and texture,5 times in total(150 days).The results showed that compared with the conventional storage, the vacuum packaging storage can effectively inhibit lipoxygenase activity(P<0.05), delay the oxidative decomposition of millet lipid(P<0.05), reduce the levels of the free fatty acids in millet(P<0.05), better maintain millet moisture(P<0.05), reduce millet yellow pigment loss(P<0.05), better keep the brightness(P<0.05), beige(P<0.05), elasticity(P<0.05) and adhesion(P<0.05), of the millet. Isolation of air and reduction of oxygen during storage can effectively delay the aging of millet, and maintain the taste of millet. At room temperature, the storage effect of millet is betterthan beforein the0.08 mm thick polyamide composite polyethylene bag under conventional closed storage, but not as good as the vacuum packaging. The storage effect of the conventional storagewas the worst. The reason for this phenomenon can be related to the oxygen content in the storage environment under different packaging methods. The quality of millet was easily deteriorated by the conventional packaging storage, because the millet was in full contact with the air,if the storage environment was rich in oxygen. The oxygen content in the environment was relatively fixed under the condition of conventional closed storage, while with the consumption of millet itself, the oxygen content was less and less, which can inhibit the oxidation of millet lipid to a certain extent(P<0.05), slow down the loss of yellow pigment, and delay the aging of millet.Under the vacuum packing mode,most of the oxygen in the storage environment was pumped out to the outside, and the oxygen content in the storage environment was greatly reduced, which effectively insulated the contact between millet and oxygen, so the vacuum packing effectively delayed the quality deterioration of millet. The storage of millet in vacuum packaging at room temperature can keep good storage quality. The results of this study have a promising practical significance for guiding the storage of millet and improving millet quality. This finding canalso provide a theoretical basis for the promotion and application of vacuum storage technology in grain production.