Abstract: To screen and identify silage fermentation products that inhibit β-carotene loss during the fermentation process,the effects of temperature (low temperature,3℃~20℃;30℃) and storage time (10,20,40,and 70 d) on the fermentation quality and β-Carotene loss of alfalfa silage were investigated. The main specific fermentation products in alfalfa silage with low β-carotene loss was identified and the mechanism for reducing β-carotene loss was revealed. The results showed that alfalfa silage stored at 30℃ had high butyric acid content and poor fermentation quality but had less β-carotene loss compared with the low temperature. Furthermore,alfalfa silage stored at 30℃ contained 5 specific silage fermentation products,and squalene content was the highest among them,which can inhibit the β-carotene destruction by lactic acid and volatile fatty acids. The inhibition effect of squalene on β-carotene destruction by acetic acid and butyric acid was better than that of lactic acid and propionic acid. Thus,it was squalene that was found out to have a function to inhibit β-carotene loss in the alfalfa silage,which revealed the mechanism of reducing β-carotene loss during ensiling of alfalfa.

Key words: Silage fermentation products, Squalene, β-Carotene

摘要： 为筛选和鉴定出抑制β-胡萝卜素损失的青贮发酵产物，本研究探讨了温度(低温3℃~20℃和30℃)和贮藏时间(10，20，40和70 d)对紫花苜蓿(Medicago sativa L.)青贮发酵品质和β-胡萝卜素损失的影响，鉴定了β-胡萝卜素损失低的紫花苜蓿青贮饲料中的主要特异性青贮发酵产物，揭示了其降低β-胡萝卜素损失的机制。结果表明：与低温贮藏相比，30℃贮藏70 d的紫花苜蓿青贮饲料丁酸含量高，发酵品质差，但β-胡萝卜素损失少，含有5种特异性青贮发酵产物。其中角鲨烯含量最高，可抑制乳酸和挥发性脂肪酸对β-胡萝卜素的破坏，且抑制乙酸和丁酸破坏β-胡萝卜素的效果优于乳酸和丙酸。因此，本研究发现了抑制β-胡萝卜素损失的角鲨烯，揭示了其在青贮过程中降低β-胡萝卜素损失的机制。

关键词: 青贮发酵产物, 角鲨烯, β-胡萝卜素