Pekkanen T J, Raevuori M
Nord Vet Med. 1976 Jul-Aug;28(7-8):381-4.
When 59 buttermilk samples were tested for the presence of antibiotics or chemostherapeutic substances by a method using the spores of Bacillus stearothermophilus var. chalidolactis all samples gave a positive reaction corresponding to about 0.01 IU penicillin per ml. When the buttermilk samples were diluted 1:1 (v/v) by a phosphate buffer, pH 6.8, only 2 were positive which were confirmed to contain penicillin. The mean pH of the unbuffered buttermilks was found to be 4.53 +/- 0.11 and when buffered 6.46 +/- 0.05. An in vitro addition of benzylpenicillin to buttermilk, to a concentration of 0.01 IU per ml, resulted in a significantly higher concentration of penicillin in the casein fraction than in the buttermilk or in the whey (Table I).
当采用嗜热脂肪芽孢杆菌嗜热栖热亚种的孢子对59份酪乳样品进行抗生素或化学治疗物质检测时，所有样品均呈现阳性反应，相当于每毫升约含0.01国际单位青霉素。当酪乳样品用pH 6.8的磷酸盐缓冲液按1:1（体积/体积）稀释时，只有2份呈阳性，经确认含有青霉素。未缓冲酪乳的平均pH值为4.53±0.11，缓冲后的pH值为6.46±0.05。在酪乳中体外添加苄青霉素至浓度为每毫升0.01国际单位时，酪蛋白部分中的青霉素浓度显著高于酪乳或乳清中的浓度（表I）。
