Effect of salt and fat reduction on the composition, lactose metabolism, water activity and microbiology of Cheddar cheese

There is an increasing focus on the development of cheese with reduced-fat and salt contents, owing to greater consumer focus on the profiling and intake management of nutrients. The current study evaluated the effects of reducing fat and salt, each by 30 and 50%, on the composition, microbiological and biochemical characteristics of Cheddar-style cheese over a 270-day ripening period. Reducing salt from 1.9 to 1.2 or 0.9% (w/w) significantly increased (P < 0.05) moisture, lactic acid, lactic acid-to-protein ratio and water activity and reduced the mean level of residual lactose and starter culture die-off during ripening. Reducing fat from 33 to 22 or 16% (w/w) resulted in significant increases in moisture, protein and lactic acid and reductions in salt-in-moisture, moisture-in-non-fat substances and lactic acid-to-protein ratio. Lactose content, pH and water activity were significantly affected by the interaction of fat and salt. The pH changed during the course of ripening, decreasing in full-fat full-salt cheese, increasing in half-fat reduced-salt and half-fat half-salt cheeses and remaining constant in other cheeses with different fat and salt levels. After 270 days of maturation at 8 A degrees C, the full-fat full-salt cheese had lower concentrations of lactic acid and free amino acids and pH and a higher lactic acid-to-protein ratio than the reduced-fat reduced-salt or half-fat half-salt cheeses. The current results, together with a follow-on communication on the impacts of reducing fat and salt on physical and sensory properties, will provide a knowledge platform which should facilitate the commercial development of reduced-salt, reduced-fat, dry-salted cheeses.