Department of Food Science, Swedish University of Agricultural Sciences, Uppsala, Sweden.
J Dairy Res. 2010 Feb;77(1):71-6. doi: 10.1017/S0022029909990434. Epub 2009 Nov 26.
Impact of milk protein composition on casein (CN) retention in curd during the milk coagulation process was studied using a model cheese making system. Individual milk samples from 110 cows in mid lactation of the Swedish Red and Swedish Holstein breeds with known genotypes of beta-casein, kappa-casein and beta-lactoglobulin were defatted, coagulated with chymosin, subjected to syneresis and subsequent pressing simulated by centrifugation. The results indicated that kappa-casein concentration of milk plays an important role in the curd formation process and initial syneresis (whey after cutting), whereas an increased CN ratio was associated with less casein in whey after simulated pressing. Increased kappa-casein concentration of milk also characterized the milk samples with no measurable loss of casein in whey, compared with milk samples with casein lost in whey, both after cutting and after simulated pressing. Concentrations of alphas1-casein, beta-casein, and total casein in milk were positively associated with fresh curd yield, which showed a strong correlation with amount of casein retained in curd. No effect of protein genotype on fresh curd yield or casein in whey was found. The beta-lactoglobulin BB genotype was associated with increased casein retention in curd, most likely due to the association of this genotype with CN ratio.
本研究使用模型干酪制作系统，考察了乳蛋白组成对乳凝固过程中酪蛋白（CN）在凝块中保留的影响。从产奶中期的瑞典红牛（Swedish Red）和瑞典荷斯坦（Swedish Holstein）品种的 110 头奶牛中分别采集了个体奶样，已知其β-酪蛋白、κ-酪蛋白和β-乳球蛋白的基因型。这些奶样经过脱脂、凝乳酶凝乳、排乳清（切割后）和随后的离心模拟压榨。结果表明，乳κ-酪蛋白浓度在凝乳形成过程和初始排乳清（切割后）中起着重要作用，而增加 CN 比值与模拟压榨后的乳清中较少的酪蛋白有关。乳中κ-酪蛋白浓度的增加还可以区分那些在乳清中没有可测量的酪蛋白损失的奶样，与那些在乳清中损失酪蛋白的奶样相比，无论是切割后还是模拟压榨后，这些奶样中都没有乳清中的酪蛋白。乳中αs1-酪蛋白、β-酪蛋白和总酪蛋白浓度与新鲜凝块产率呈正相关，这与凝块中保留的酪蛋白量有很强的相关性。未发现蛋白质基因型对新鲜凝块产率或乳清中酪蛋白有影响。β-乳球蛋白 BB 基因型与凝块中酪蛋白保留增加有关，这很可能是由于该基因型与 CN 比值有关。
