Reddy C A, Henderson H E, Erdman M D
Appl Environ Microbiol. 1976 Dec;32(6):769-76. doi: 10.1128/aem.32.6.769-776.1976.
A simple and efficient process for the production of a ruminant feed supplement, rich in crude protein (defined as total N X 6.25), by bacterial fermentation of cheese whey has been developed. The lactose in unpasteurized whey is fermented to lactate acid by Lactobacillus bulgaricus at a temperature of 43 degrees C and pH 5.5. The lactic acid produced is continually neutralized with ammonia to form ammonium lactate. The fermented product is concentrated by evaporation to a solids content of about 70% and adjusted to pH 6.8 with additional ammonia. The concentrated product contains about 55% crude protein. Approximately 6 to 8% of the crude protein is derived from bacterial cells. 17% from whey proteins, and 75 to 77% from ammonium lactate. The efficiency of conversion of lactose to lactic acid usually exceeds 95%. The fermentation time is greatly reduced upon the addition of 0.2% yeast extract or 0.1% corn steep liquor as a source of growth factors. Whey containing lactose at concentrations up to 7% can be fermented efficiently, but at higher concentrations lactose is fermented incompletely. The process has been scaled up to a pilot plant level, and 40 tons of concentrated product were produced fro animal feeding trials, without ever encountering putrefactive spoilage.
已开发出一种通过干酪乳清的细菌发酵生产富含粗蛋白（定义为总氮×6.25）的反刍动物饲料添加剂的简单高效方法。在43摄氏度和pH值5.5的条件下，保加利亚乳杆菌将未巴氏杀菌乳清中的乳糖发酵成乳酸。产生的乳酸用氨持续中和以形成乳酸铵。发酵产物通过蒸发浓缩至固体含量约为70%，并用额外的氨将pH值调至6.8。浓缩产物含有约55%的粗蛋白。约6%至8%的粗蛋白来自细菌细胞，17%来自乳清蛋白，75%至77%来自乳酸铵。乳糖转化为乳酸的效率通常超过95%。添加0.2%酵母提取物或0.1%玉米浆作为生长因子来源时，发酵时间会大大缩短。乳糖浓度高达7%的乳清可以有效发酵，但浓度更高时乳糖发酵不完全。该工艺已扩大到中试工厂规模，已生产出40吨浓缩产物用于动物饲养试验，从未遇到过腐败变质问题。
