The Effect of Freezing on Different Bacterial Counts in Raw Milk
The Effect of Freezing on Different Bacterial Counts in Raw Milk
复制标题
冷冻对原奶中不同细菌计数的影响
DOI：
10.5539/ijb.v7n4p9
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
N. I. Alrabadi
中科院分区：
文献类型：
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作者：
N. I. Alrabadi
研究了冷冻对原料乳中细菌总数的影响。具体而言，我们估计了总细菌计数和总大肠菌群、耐盐细菌、葡萄球菌属、嗜热乳杆菌，嗜热乳杆菌，明串珠菌属，乳球菌和链球菌。将30份生牛乳样品在-18-20°C下冷冻8周，并每周进行检测。结果表明，随着冷冻时间的延长，细菌总数显著下降。8周后，鲜乳中的菌落总数（6.5 × 105 cfu/ml）下降到冻乳中的（5.0 × 103 cfu/ml），差异有统计学意义（P1%）。不同菌群间细菌计数的下降程度不同。耐盐菌下降幅度最大，由9.8 × 105 cfu/ml降至7.6 × 103 cfu/ml，葡萄球菌下降幅度最小，由3.6 × 103 cfu/ml降至8.2 × 101 cfu/ml。该研究建议冷冻作为原料奶的重要储存方法。
This study had investigated the effect of freezing on the bacterial counts in raw milk. In specific, we estimated the total bacterial counts and the counts of total coliform, Salt tolerant bacteria, Staphylococcus spp ., Thermopilic Lactobacilli, Mesophilic Lactobacilli, Leuconostoc spp., Lactococci and Streptococci. Thirty samples of raw cow milk were frozen at -18-20°C for eight weeks and tested on a weekly basis. The results showed that the bacterial counts had significantly decreased as the freezing period increased. Thus, the total count had significantly decreased from (6.5*10 5 cfu/ml) in fresh milk to (5.0*10 3 cfu/ml) in frozen milk after eight weeks (P1%). The decrease in the bacterial counts was different between the different bacterial groups. The highest decrease was for Salt tolerant bacteria from (9.8*10 5 cfu/ml) to (7.6*10 3 cfu/ml), while the lowest decrease was for Staphylococcus spp from (3.6*10 3 cfu/ml) to (8.2*10 1 cfu/ml). The study recommends freezing as an important storage method for raw milk.