Effect of pH and calcium concentration on proteolysis in mozzarella cheese.
Low-moisture Mozzarella cheeses (LMMC), varying in calcium content and pH, were made using a starter culture (control; CL) or direct acidification (DA) with lactic acid or lactic acid and glucono-delta-lactone. The pH and calcium concentration significantly affected the type and extent of proteolysis in Mozzarella cheese during the 70-d storage period at 4 degrees C. For cheeses with a similar pH, reducing the calcium-to-casein ratio from -29 to 22 mg/g of protein resulted in marked increases in moisture content and in primary and secondary proteolysis, as indicated by polyacrylamide gel electrophoresis and higher levels of pH 4.6- and 5%-PTA-soluble N. Increasing the pH of DA cheeses of similar moisture content, from approximately 5.5 to 5.9, while maintaining the calcium-to-casein ratio almost constant at approximately 29 mg/g, resulted in a decrease in primary proteolysis but had no effect on secondary proteolysis. Comparison of CL and DA cheeses with a similar composition showed that the CL cheese had higher levels of alpha(s1)-CN degradation, pH 4.6- and 5%-PTA-soluble N. Analysis of pH 4.6-soluble N extracts by reverse-phase HPLC showed that the CL cheese had higher concentrations of compounds with low retention times, suggesting higher concentrations of low molecular mass peptides and free amino acids.
Feeney
E P
EP
Department of Food Science and Technology, University College, Cork, Ireland.
Guinee
T P
TP
Fox
P F
PF
D000818:Animals; D002118:Calcium / Q000032:analysis / Q000737:chemistry*; D002364:Caseins / Q000032:analysis / Q000378:metabolism*; D002611:Cheese / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D012085:Chymosin / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005511:Food Handling / Q000379:methods; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry; D008894:Milk Proteins / Q000737:chemistry*; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D011897:Random Allocation; D012995:Solubility; D013997:Time Factors
D002364:Caseins; D008894:Milk Proteins; D019344:Lactic Acid; D012085:Chymosin; D009584:Nitrogen; D002118:Calcium