Kotz C M, Furne J K, Savaiano D A, Levitt M D
University of Minnesota, Department of Food Science and Nutrition, St. Paul 55108.
J Dairy Sci. 1994 Dec;77(12):3538-44. doi: 10.3168/jds.S0022-0302(94)77296-9.
Lactose in yogurt is better absorbed by lactase-deficient subjects than is an equivalent quantity of lactose in milk, presumably because of the microbial activity of the beta-galactosidase present in yogurt. In this study, we describe a process that increases the beta-galactosidase of yogurt 5- to 6-fold and the ability of this high lactase yogurt to enhance lactose absorption in lactase-deficient subjects. These subjects ingested the yogurt meals after a 12-h fast, and lactose malabsorption was determined by measuring breath hydrogen. Breath hydrogen was reduced 39% following ingestion of high lactase yogurt from that after consumption of conventional yogurt, indicating that the high lactase yogurt enhanced lactose absorption. However, the reduction after high lactase yogurt was less than expected, given the 5- to 6-fold increment in beta-galactosidase measured in vitro. In vivo activity of beta-galactosidase requires that the enzyme resist acid denaturation in the stomach. The beta-galactosidase in high lactase yogurt was much less acid resistant than was the beta-galactosidase in conventional yogurt, and the relative inability of high lactase yogurt to enhance lactose absorption was likely due to the destruction of the beta-galactosidase in the stomach.
与牛奶中等量的乳糖相比，乳糖不耐受的受试者对酸奶中的乳糖吸收更好，这可能是因为酸奶中存在的β-半乳糖苷酶具有微生物活性。在本研究中，我们描述了一种将酸奶中β-半乳糖苷酶增加5至6倍的方法，以及这种高乳糖酶酸奶增强乳糖不耐受受试者乳糖吸收的能力。这些受试者在禁食12小时后食用酸奶餐，通过测量呼出气中的氢气来确定乳糖吸收不良情况。摄入高乳糖酶酸奶后呼出气中的氢气比食用传统酸奶后减少了39%，这表明高乳糖酶酸奶增强了乳糖吸收。然而，鉴于体外测量的β-半乳糖苷酶增加了5至6倍，高乳糖酶酸奶后的减少幅度低于预期。β-半乳糖苷酶的体内活性要求该酶在胃中抵抗酸变性。高乳糖酶酸奶中的β-半乳糖苷酶比传统酸奶中的β-半乳糖苷酶耐酸性差得多，高乳糖酶酸奶增强乳糖吸收的相对能力不足可能是由于胃中β-半乳糖苷酶被破坏。
