小米脂氧合酶活性与储藏稳定性关系

Relationship Between Lipoxygenase Activity and Storage Stability of Foxtail Millet

为研究小米中脂氧合酶(LOX)活性和储藏稳定性的关系,初步探索小米褪色机制,以褪色快的小米品种(‘谷丰2号’、‘公谷63号’)、褪色慢的小米品种(‘大青秸’、‘红苗牛头沟’)为试验材料,对其进行人工老化处理,并测定人工老化处理前后小米的脂氧合酶活性、米色、类胡萝卜素、丙二醛(MDA)含量的变化。同时,利用HPLC对小米类胡萝卜素提取液进行分析,比较4个小米品种中叶黄素、玉米黄质及β-胡萝卜素的变化差异,分析小米脂氧合酶活性与类胡萝卜素及其主要组分的相关性。结果表明,经老化处理后,4个小米品种的LOX活性、米色b*值和类胡萝卜素含量均下降,MDA含量升高。‘大青秸’、‘红苗牛头沟’小米与‘谷丰2号’、‘公谷63号’小米相比,其米色、类胡萝卜素含量和MDA含量变化较小,储藏稳定性较好。HPLC分析表明,老化处理前后4个小米品种叶黄素、玉米黄质的变化无明显差异,而β-胡萝卜素含量的变化存在明显差异;相关性分析表明,老化处理前后LOX活性与β-胡萝卜素含量呈负相关,表明LOX可能与β-胡萝卜素发生偶联,进而导致小米类胡萝卜素含量降低。本研究结果为耐储藏小米的遗传育种提供了一定的理论基础。

To investigate the fading mechanism and relationship between lipoxygenase（LOX） activity and storage stability of foxtail millet. The fast-fading（Gufeng 2 and Gonggu 63） and slow-fading（Daqingju and Hong miao niu tougou）varieties were selected. Four foxtail millet varieties were aged artificially,and the changes of LOX activity and color,carotenoid and malondialdehyde（MDA） content were analyzed. The extraction mixture of carotenoid were further measured by HPLC to compare the difference of lutein,zeaxanthin and β-carotene. These physiological indicators were subsequently used for correlation analysis. The results showed that after artificial ageing,the LOX activity,the color of foxtail millet and carotenoid content of the four cultivars were decreased,and the content of MDA was increased.However,compared with high LOX activities cultivates（Gufeng 2 and Gonggu 63）,low LOX activities cultivates（Daqingju and Hongmiao niutougou） were tested at good storage stability,and their carotenoid content decreased and MDA content rose at a slower rates. HPLC analysis showed that there was no significant difference between the decrease of lutein and zeaxanthin in four foxtail millet varieties,but there were significant difference in β-carotene content among the four foxtail millet varieties. The correlation analysis showed that LOX activity was negatively correlated with β-carotene,which indicated that LOX coupling with β-carotene,resulted in the reduction of carotenoid in foxtail millet.This study provides a theoretical basis for foxtail millet breeding with increasied stability.