Casein retention in curd and loss of casein into whey at chymosin-induced coagulation of milk

Abstract

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.

RNA sequencing to study gene expression and single nucleotide polymorphism variation associated with citrate content in cow milk

“…This explains the common practice in commercial cheese making of adding calcium chloride in cheese making before the enzymatic coagulation step so coagulation takes place normally, but aging cheeses with high citrate levels develop better flavors (Dudley and Steele, 2005;Brickley et al, 2009). Furthermore, an increasing concentration of lactose in milk has been shown to exert a beneficial effect on the formation of acid-induced milk gels (Hallén et al, 2010). In this context, lactose is the most important osmoregulator of milk synthesis and is, to some extent, correlated with the total protein and casein content of milk, whereby lower levels of citrate content in milk induced the caseins to become overloaded with calcium, and then precipitate (Hallén et al, 2007).…”

Composition of major proteins in cow milk differing in mean protein concentration during the first 155 days of lactation and the influence of season as well as short-term restricted feeding in early and mid-lactation

“…The yield and composition of major bovine milk proteins determine the value of the product, depending on how the milk will be used. For cheese making a higher casein content, particularly higher κ-CN, correlates to increased curd yield, stronger curd firmness, and less casein loss in whey (Hallen et al, 2010). The composition of milk and milk proteins is influenced by many factors.…”

Factor analysis as a tool to estimate association among individual proteins and other milk components with casein micelle size and cheese yield

“…Wedholm et al (2006) reported that cheese yield was improved at increasing concentrations of κ-casein (κ-CN), α S 1-casein (α S 1-CN), β-casein (β-CN) and β-lactoglobulin (β-LG) in milk. Hallén et al (2010) also detected that increased κ-CN was associated with higher amount of casein retained in curd.…”