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.
Department of Food Science and Technology, University College, Cork, Ireland.
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Feeney
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Guinee
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Fox
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