Manufacture of Cheddar cheese with and without adjunct lactobacilli under controlled microbiological conditions

Cheddar cheeses were manufactured under controlled microbiological conditions to study the influence of selected strains of mesophilic lactobacilli on proteolysis and flavour development. In each of two trials, a control cheese (containing only a Lactococcus starter) and four experimental cheeses (containing the Lactococcus starter and adjunct lactobacilli) were manufactured. The Lactobacillus inocula were Lb. casei ssp. casei (4 strains), Lb. casei ssp. pseudoplantarum (4 strains), Lb. curvatus (4 strains) or Lb. plantarum (2 strains). In the experimental cheeses, counts of lactobacilli ranged from 10⁴ to 10⁵ cfu g^-1 at milling and increased to ~5 x 10⁷ cfu g^-1 after 4 weeks. Control cheeses remained free of lactobacilli for up to 97 days and thereafter the counts did not exceed ~5 x 10⁵ cfu g^-1. Addition of lactobacilli positively influenced flavour acceptability of the cheese after ripening for 6 months at 7°C. Cheeses manufactured with Lb. plantarum or Lb. casei ssp. pseudoplantarum adjuncts received the best grades. PAGE and RP-HPLC indicated only relatively minor differences in proteolysis between the control and experimental cheeses; however, the experimental cheeses showed higher levels of free amino acids, as well as differences in profiles of individual free amino acids, when compared to the controls. The addition of low numbers of selected strains of Lactobacillus spp. to cheesemilk, while having only a relatively minor influence on proteolysis, positively influenced by quality of Cheddar cheese.