E (Kika) de la Garza American Institute for Goat Research, Langston University, Langston, OK 73050, USA.
J Dairy Sci. 2010 Apr;93(4):1345-54. doi: 10.3168/jds.2009-2366.
This study investigated the effect of somatic cell count (SCC) in goat milk on yield, free fatty acid (FFA) profile, and sensory quality of semisoft cheese. Sixty Alpine goats without evidence of clinical mastitis were assigned to 3 groups with milk SCC level of <500,000 (low), 500,000 to 1,000,000 (medium), and 1,000,000 to 1,500,000 (high) cells/mL. Thirty kilograms of goat milk with mean SCC levels of 410,000 (low), 770,000 (medium), and 1,250,000 (high) cells/mL was obtained for the manufacture of semisoft cheese for 2 consecutive weeks in 3 lactation stages. The composition of milk was analyzed and cheese yield was recorded on d 1. Cheese samples on d 1, 60, and 120 were analyzed for total sensory scores, flavor, and body and texture by a panel of 3 expert judges and were also analyzed for FFA. Results indicated that milk composition did not change when milk SCC varied from 214,000 to 1,450,000 cells/mL. Milk with higher SCC had a lower standard plate count, whereas coliform count and psychrotrophic bacteria count were not affected. However, milk components (fat, protein, lactose, casein, and total solids) among the 3 groups were similar. As a result, no significant differences in the yield of semisoft goat cheeses were detected. However, total sensory scores and body and texture scores for cheeses made from the high SCC milk were lower than those for cheeses made from the low and medium SCC milks. The difference in milk SCC levels also resulted in diverse changes in cheese texture (hardness, springiness, and so on) and FFA profiles. Individual and total FFA increased significantly during ripening, regardless the SCC levels. It is concluded that SCC in goat milk did not affect the yield of semisoft cheese but did result in inferior sensory quality of aged cheeses.
本研究旨在探讨羊奶体细胞计数(SCC)对半软奶酪产量、游离脂肪酸(FFA)谱和感官品质的影响。选择 60 只无临床乳腺炎证据的阿尔卑斯山羊,根据 SCC 水平分为 3 组,分别为<500,000(低)、500,000-1,000,000(中)和 1,000,000-1,500,000(高)细胞/ml。在 3 个泌乳阶段连续 2 周,用 SCC 均值分别为 410,000(低)、770,000(中)和 1,250,000(高)细胞/ml 的羊奶,制造 30kg 半软奶酪。于第 1 天分析奶样的成分并记录奶酪产量。第 1、60 和 120 天的奶酪样品由 3 位专家组成的小组进行总感官评分、风味、口感和质地分析,并进行 FFA 分析。结果表明,当 SCC 从 214,000 变化到 1,450,000 细胞/ml 时,奶成分没有变化。高 SCC 的奶样有较低的标准平板计数,而大肠菌群和嗜冷菌计数不受影响。然而,3 组奶样的成分(脂肪、蛋白质、乳糖、酪蛋白和总固体)相似。因此,半软山羊奶酪的产量没有显著差异。然而,高 SCC 奶样制成的奶酪的总感官评分和口感和质地评分低于低和中 SCC 奶样制成的奶酪。SCC 水平的差异也导致奶酪质地(硬度、弹性等)和 FFA 谱的变化。在成熟过程中,无论 SCC 水平如何,个体和总 FFA 均显著增加。结论是,羊奶的 SCC 不会影响半软奶酪的产量,但会导致陈奶酪的感官品质下降。