Age-Related Changes in the Water Phase of Mozzarella Cheese

Changes in the water-holding capacity of low moisture Mozzarella cheese during aging were evaluated by measuring the amount of serum expressed from the cheese upon centrifugation at 12,500 x g for 75 min at 25•C.Low moisture Mozzarella cheeses (n =3) were obtained the day after commercial manufacture and stored at 4•C.Expressible serum was obtained at 2, 4, 8, 12, and 16 d after manufacture; analyzed for concentrations of CP and protein that was soluble at pH 4.6, Ca, P, K, Mg, Na, and Zn; and evaluated for proteins and peptides by urea-PAGE.Quantity of expressible serum decreased dramatically during storage, indicating substantial increase in water-holding capacity.Both CP and protein that was soluble at pH 4.6 in expressible serum increased during storage; however, CP content was higher and increased faster than protein that was soluble at pH 4.6.Urea-PAGE confinned that unhydrolyzed cxsi-, CX s 2-, and especially t3-CN accounted for a large share of the CP in the expressible serum.Concentration of Zn increased during aging, unlike that of other elements.A model that is based on the swelling and solubilizing action of NaCI on the protein matrix is proposed to account for the increases in water-holding capacity and the unhydrolyzed caseins in the water phase of Mozzarella cheese during aging.