■为了研究添加酸奶发酵剂的保存效果,山梨酸钾和柠檬酸对需氧细菌的计数,乳杆菌属。,嗜热链球菌和大肠杆菌,白利糖度百分比,pH值,蛋白质,在环境温度下储存的初乳收集后0、7和14天的脂肪和无水乳糖浓度。
■从怀卡托地区的10个农场收集大约2升的第一挤奶初乳。混合后,它被分成五个400毫升的子样本,并随机分配给一个对照(两个子样本),或者用酸奶治疗,山梨酸钾,或柠檬酸防腐剂。在整个试验过程中,样品在环境温度下保持在实验室中,盖子微开,并且使用无菌刮刀每天搅拌15-30秒。在第0、7和14天测试子样品。在第0天和第14天,需氧细菌(通过需氧平板计数(APC)),乳杆菌属。,大肠杆菌和嗜热链球菌计数,pH值,白利糖度百分比,蛋白质,脂肪和无水乳糖进行测量。在第7天仅完成细菌计数。数据使用非参数聚类引导抽样进行分析,以估计治疗的效果,时间,以及它们对结果变量的相互作用。
■与对照样品相比,在第7天,山梨酸钾的APC(1.0(90%CI=0.6-1.6)×108cfu/mL)比酸奶(7.3(90%CI=4.1-11)×108cfu/mL)低约7倍,并且比柠檬酸低约3倍(3.2(90%CI=0.2-4.3)×108cfu/mL),保持低到第14天。在第7天,与对照样品相比,所有防腐剂都降低了大肠杆菌的生长,但是山梨酸钾的生长低于其他防腐剂。对于乳酸杆菌。,在第7天,具有酸奶防腐剂的样品具有比其他两种防腐剂更大的计数。与其他处理相比,山梨酸钾降低了嗜热链球菌的生长,特别是在第7天,与其他三组相比,嗜热链球菌每毫升少7-10倍。随着时间的推移,所有组都显示出明显的酸化,几天内和治疗组的变化很小。无论治疗如何,都没有证据表明脂肪或蛋白质百分比随时间的变化。
■需氧菌和大肠杆菌在未保存的初乳中广泛增殖。与未保存的初乳相比,所有防腐剂都减少了大肠杆菌计数,但是山梨酸钾在减少大肠杆菌和需氧细菌方面比酸奶或柠檬酸更有效。
UNASSIGNED: To investigate the effect of
preservation by addition of yoghurt starter, potassium sorbate and citric acid on counts of aerobic bacteria, Lactobacillus spp., Streptococcus thermophilus and coliforms, Brix percentage, pH, protein, fat and anhydrous lactose concentrations at 0, 7 and 14 days after collection for colostrum stored at ambient temperature.
UNASSIGNED: Approximately 2 L of first milking colostrum was collected from 10 farms in the Waikato region. Following mixing, it was split into five 400-mL sub-samples and allocated randomly to a control (two sub-samples), or treatment with yoghurt, potassium sorbate, or citric acid preservative. Throughout the trial samples remained in the laboratory at ambient temperature with the lids slightly ajar, and were stirred daily for 15-30 seconds using a sterile spatula. Sub-samples were tested on Days 0, 7 and 14. On Days 0 and 14 aerobic bacteria (by aerobic plate count (APC)), Lactobacillus spp., coliforms and Streptococcus thermophilus counts, pH, Brix percentage, protein, fat and anhydrous lactose were measured. On Day 7 only bacterial counts were completed.The data were analysed using non-parametric clustered bootstrap sampling to estimate the effect of treatment, time, and their interaction on the outcome variables.
UNASSIGNED: Compared to control samples, on Day 7 the APC for potassium sorbate (1.0 (90% CI = 0.6-1.6) × 108 cfu/mL) was approximately seven-fold lower than for yoghurt (7.3 (90% CI = 4.1-11) × 108 cfu/mL), and approximately three-fold lower than citric acid (3.2 (90% CI = 0.2-4.3) × 108 cfu/mL) remaining low to Day 14. All preservatives reduced coliform growth compared to control samples at Day 7 but growth was lower for potassium sorbate than the other preservatives. For Lactobacillus spp., at Day 7, samples with yoghurt preservative had greater counts than the other two preservatives. Potassium sorbate reduced growth of S. thermophilus compared to the other treatments, especially at Day 7, with 7-10 times fewer S. thermophilus per mL compared to the other three groups. All groups showed an obvious acidification over time, with very little variation within days and treatment groups. There was no evidence for change in fat or protein percentage over time regardless of treatment.
UNASSIGNED: Aerobic and coliform bacteria proliferate extensively in unpreserved colostrum. All preservatives decreased coliform counts compared to un-preserved colostrum, but potassium sorbate was more effective at decreasing both coliforms and aerobic bacteria than either yoghurt or citric acid.