The influence of alkaline earth metal equilibria on the rheological, melting and textural properties of Cheddar cheese

摘要

The total calcium content of cheese, along with changes in the equilibrium between soluble and casein (CN)-bound calcium during ripening can have a major impact on its rheological, functional and textural properties; however, little is known about the effect of other alkaline earth metals. NaCl was partially substituted with MgCl_2 or SrCl_2 (8·7 and 11 ·4 g/kg curd, respectively) atthe salting stage of cheesemaking to study their effects on cheese. Three cheeses were produced: Mg supplemented (+Mg), Sr supplemented (+Sr) and a control Cheddar cheese. Ca, Mg and Sr contents of cheese and expressible serum obtained therefrom were determined by atomic absorption spectroscopy. Addition of Mg~(2+)or Sr~(2+) had no effect on % moisture, protein, fat and extent of proteolysis. A proportion of the added Mg~(2+)and Sr~(2+) became CN-bound. The level of CN-bound Mg was higher in the +Mg cheese than the control throughout ripening. The level of CN-bound Ca and Mg decreased during ripening in all cheeses, as did % CN-bound Sr in the + Sr cheese. The presence of Sr~(2+) increased % CN-bound Ca and Mg at a number of ripening times. Adding Mg~(2+) had no effect on % CN-bound Ca. The +Sr cheese exhibited a higher C at 70℃ and a lower LT_(max) than the control and +Mg cheeses throughout ripening. The +Sr cheese had significantly lower meltability compared with the control and + Mg cheeses after 2 months of ripening. Hardness values of the + Sr cheese were higher at week 2 than the +Mg and control cheeses. Addition of Mg~(2+) did not influence the physical properties of cheese. Supplementing cheese with Sr appeared to have effects analogous to those previously reported for increasing Ca content. Sr~(2+) may form and/or modify nanocluster crosslinks causing an increase in the strength of the para-casein matrix.