Department of Dairy and Animal Science, The Pennsylvania State University, University Park 16802, USA.
J Dairy Sci. 2010 Mar;93(3):961-7. doi: 10.3168/jds.2009-2388.
A study was conducted to identify the optimal temperature and time at which heat treatment of bovine colostrum would least change viscosity and IgG concentrations yet reduce bacterial count. First-milking colostrum with >50g of immunoglobulins/L (measured by colostrometer) was collected from 30 Holstein cows. Aliquots of colostrum were heated for 0, 30, 60, or 90min at 57, 60, or 63 degrees C in a water bath. Samples were examined for viscosity, IgG(1), and IgG(2) concentrations, standard plate count, coagulase-negative staphylococci, environmental streptococci, coliform, gram-negative noncoliform, Streptococcus agalactiae, and Staphylococcus aureus counts. All heat treatments reduced counts of all bacteria groups measured compared with untreated colostrum samples. Heat treatment at >or=60 degrees C denatured IgG(1) compared with untreated colostrum; however, colostral IgG(2) levels were not reduced when temperature was held at 60 degrees C for <60min. Viscosity was not affected when temperature was held at 60 degrees C for <60min. In this study, heat treatment of bovine colostrum at 60 degrees C for 30 or 60min reduced bacterial count, slightly reduced IgG concentration, and did not affect viscosity.
一项研究旨在确定牛初乳热处理的最佳温度和时间，以最大限度地降低其粘度和 IgG 浓度的变化，同时降低细菌数量。从 30 头荷斯坦奶牛中收集初乳量大于 50g/升的初乳（用乳脂计测量）。将初乳等分试样在水浴中于 57、60 或 63°C 下加热 0、30、60 或 90min。检查样品的粘度、IgG(1)和 IgG(2)浓度、标准平板计数、凝固酶阴性葡萄球菌、环境链球菌、大肠菌群、革兰氏阴性非大肠菌群、无乳链球菌和金黄色葡萄球菌计数。与未处理的初乳样品相比，所有热处理均降低了所测量的所有细菌群的数量。与未经处理的初乳相比，>60°C 的热处理使 IgG(1)变性；然而，当温度保持在 60°C 以下 60min 时，初乳 IgG(2)水平并未降低。当温度保持在 60°C 以下 60min 时，粘度不受影响。在这项研究中，牛初乳在 60°C 下处理 30 或 60min 可降低细菌数量，略微降低 IgG 浓度，且不影响粘度。
