Department of Biological Sciences, University of Limerick, Limerick, V94 T9PX, Ireland.
Department of Food Science, University of Guelph, Guelph, Ontario, N1G 2W1, Canada.
J Dairy Sci. 2020 Dec;103(12):10963-10985. doi: 10.3168/jds.2020-18960. Epub 2020 Oct 1.
The importance of starter cultures to cheese manufacture and ripening is well known. Starters are inoculated into cheese milk at a level of ∼10 cfu/mL either from a bulk culture or using commercial direct-to-vat cultures. Before ripening, starters grow in the milk to reach populations of 10 to 10 cfu/g of curd depending on processing variables such as cook temperature, inclusion of washing steps, degree of partitioning with curds and whey, and importantly salt addition rate. Inherent strain-related properties also determine final populations in the curd following manufacture and include temperature sensitivity, salt sensitivity, presence of prophage, autolytic and permeabilization properties (which are influenced by processing steps), presence and type of cell envelope proteinase, and metabolic activity. Ripening of important industrial cheese varieties such as Cheddar, Dutch, Swiss, and Italian-type cheese varieties is characterized by extended storage under temperature-controlled conditions enabling characteristic flavor and texture development to occur. Over ripening, microbiological, biochemical and enzymatic changes occur with a decline in starter viability, release of intracellular enzymes, hydrolysis of proteins, carbohydrates and lipids, and formation of a range of volatile and nonvolatile flavor components. Recent reports suggest that starter strains may be present during the later stages of ripening and therefore their potential role needs to be reconsidered. This review will focus on our current understanding of starter viability and vitality during cheese ripening and will also review the area of starter permeabilization, autolysis, and enzyme release.
众所周知，起始培养物对奶酪的制造和成熟非常重要。起始培养物以约 10 cfu/mL 的水平接种到奶酪乳中，无论是来自批量培养物还是使用商业直接到罐培养物。在成熟之前，起始培养物在牛奶中生长，达到 10 到 10 cfu/g 凝乳的种群，具体取决于加工变量，如烹饪温度、是否包含洗涤步骤、凝乳和乳清的分区程度，以及重要的盐添加率。固有菌株相关特性也决定了制造后凝乳中的最终种群，包括温度敏感性、盐敏感性、存在噬菌体、自溶和渗透特性（受加工步骤影响）、存在和类型的细胞包膜蛋白酶和代谢活性。切达干酪、荷兰干酪、瑞士干酪和意大利干酪等重要工业奶酪品种的成熟特征是在控温条件下进行长时间储存，从而使特征风味和质地得以发展。过度成熟会导致微生物学、生物化学和酶学变化，起始培养物的活力下降，细胞内酶的释放，蛋白质、碳水化合物和脂肪的水解，以及一系列挥发性和非挥发性风味成分的形成。最近的报告表明，在成熟的后期阶段可能存在起始菌株，因此需要重新考虑它们的潜在作用。本综述将重点介绍我们目前对奶酪成熟过程中起始培养物活力和生命力的理解，并回顾起始培养物渗透、自溶和酶释放的领域。
