回温抑制鲜切马铃薯褐变及影响游离氨基酸代谢的研究

马铃薯鲜切后表面易发生褐变,严重影响其商品价值,为了解决低温贮藏后马铃薯鲜切褐变的问题,采用20℃下回温处理20 d,探讨其对鲜切马铃薯褐变、多酚氧化酶(PPO)、过氧化物酶(POD)活性、游离氨基酸及丙二醛(MDA)含量的影响。结果表明,回温处理显著地抑制了鲜切马铃薯的褐变,抑制了PPO和POD活性,降低了切前初始总游离氨基酸的含量；其中游离酪氨酸、缬氨酸、丝氨酸回温后及切后均显著低于对照；鲜切后贮藏前期,游离天冬氨酸、丙氨酸显著降低,游离甘氨酸显著升高；回温及鲜切后,游离脯氨酸的含量显著升高,MDA含量显著降低。由此表明,回温处理通过抑制马铃薯PPO和POD活性,影响游离酪氨酸、丝氨酸、天冬氨酸、缬氨酸、丙氨酸、甘氨酸的含量,提高脯氨酸并降低MDA含量,显著抑制了低温贮藏鲜切马铃薯的褐变。

Warming on Browning Inhibition and Free Amino Acid Metabolism of Fresh-cut Potatoes

The browning of fresh-cut potatoes occurs especially when tubers are stored at cold storage, which affects the commodity value. To solve this problem, warming treatment at 20°C for 20 d was applied and the effect on activities of PPO and POD, content of free amino acid and MDA were measured. The results showed that, warming treatment effectively inhibited the browning of fresh-cut potatoes and activities of PPO and POD. After warming treatment, the content of total free amino acid reduced significantly. The contents of free tyrosine, valine and serine during warming and post- cut period were lower than that of the control. The contents of free aspartic acid and alanine were lower while the content of free glycine was higher than control during the early stage of the post-cut storage. However, the content of free proline was higher than control both during pre- cut and post- cut period. Besides, warming treatment slowed down the accumulation of MDA content. The study shows that warming treatment of potato tubers after cold storage inhibits PPO and POD activities, influences the content of free tyrosine, serine, aspartic acid, valine, alanine and glycine, improves the content of free proline, reduces MDA accumulation and eventually inhibits the browning of fresh- cut potatoes.