Surface Hydrophobicity of αs1 -I, αs1 -Casein A and B and Its Implications in Cheese Structure

The first major proteolytic cleavage during Cheddar cheese maturation is the scission of α s1 -casein to give a small peptide and α s1 -I. Previously this proteolytic step was correlated with changes in the rheological properties of cheese, notably a lower elasticity and a decrease in the force required to fracture the cheese. Using cis -parinaric acid and 1,8-anilinonaphthalene sulfonate, we showed that α s1 -I and α s1 -casein A have lower surface hydrophobicities than α s1 -casein B. The peptide segment involving residues 14 to 24 of the α s1 -casein B sequence must be important in the formation of a hydrophobic interaction site, and an extensive network of hydrophobically bonded α s1 -casein molecules is probably important in young cheese as well as in concentrated casein solutions.