牛奶中乳过氧化物酶系统及其抗菌作用的研究

Study on the Lactoperoxicdase-Thiocynate-Hyarogen Peroxide System and its Antibacterial Activity in the Milk

采用中国黑白花奶牛混合鲜奶,研究了乳过氧化物酶(LP)活力,H_2O_2对乳过氧化物酶系统(LPS)的体外活化作用,并用滴定酸度评价奶的抗菌活性。结果表明:牛奶中LP活力很高,70℃加热15分钟酶活力损失约60％。LP能催化H_2O_2氧化SCN^-,随H_2O_2浓度增加(0～0.5mmol/L),30℃保温5分钟SCN^-相对含量由100％下降至57.4％,加入I^-能促进SCN^-消失。用H_2O_2活化的牛奶抗菌活性增强,且当SCN同H_2O_2浓度相等时效果最佳。I^-对这种抗菌作用有一定削弱作用。中草药水抽提物对LPS有一定影响,加入0.5％的葛根或丹皮水抽提液能增加活化奶和原奶的抗菌活性,并加速SCN^-消失。牛奶中LPS的研究对奶牛乳房炎、犊牛腹泻的防治及奶的保鲜、加工等有一定意义。

Mixed fresh skim milk of Chinese Holstein Cows was used in this experiment to study the activity of lactoperoxidase (LP), and the activation of lactoperoxidase-thioeynate-Hydrogen Peroxide system(LPS)in vitro. The antibacterial activity of LPS was assessed by titrating the acidity of the milk. The results showed that the activity of LP in the milk was very high, and its activity decreased by approximately 60 percent after heated at 70℃ for 15 min. SCN- was oxidated by LP catalysed-H_2o_2, and in 5 min after adding H_2O_2, the relative concentration of SCN^-at 30℃ decreased from 100% to 57.4% with the increased of H_2O_2 concentration (0～0.5mmol/L). the disappearance of SCN^- was accelerated by I^-. The antibacterial activity of 24 hrs of milk at 37℃ increased by adding H_2O_2, and reached its maximum when the concentrations of SCN^- and H_2O_2 were equal, but was weakened by adding I^-. LPS was affected by adding water soluble components of traditional Chinese Herbal medicine, the antibacterial activity of activated milk on raw skim milk was increased by adding 0. 5 percent (v/v)solution of water soluble extracts of Kudzu Vine root or the root bark of the tree Peony.