title: The influence of alkaline earth metal equilibria on the rheological, melting and textural properties of Cheddar cheese.
abstract: 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 MgCl2 or SrCl2 (8·7 and 11·4 g/kg curd, respectively) at the 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 Mg2+ or Sr2+ had no effect on % moisture, protein, fat and extent of proteolysis. A proportion of the added Mg2+ and Sr2+ 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 Sr2+ increased % CN-bound Ca and Mg at a number of ripening times. Adding Mg2+ had no effect on % CN-bound Ca. The +Sr cheese exhibited a higher G' at 70 °C and a lower LTmax 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 Mg2+ 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. Sr2+ may form and/or modify nanocluster crosslinks causing an increase in the strength of the para-casein matrix.
authors.affiliation: School of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
authors.forename: Darren R
authors.initials: DR
authors.lastname: Cooke
authors.forename: Paul L H
authors.initials: PL
authors.lastname: McSweeney
mesh_terms: D002118:Calcium / Q000737:chemistry; D002611:Cheese / Q000032:analysis* / Q000592:standards*; D005504:Food Analysis / Q000592:standards*; D005511:Food Handling / Q000379:methods; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry*; D012212:Rheology; D013324:Strontium / Q000737:chemistry*; D013997:Time Factors
chemical_list: D008274:Magnesium; D002118:Calcium; D013324:Strontium