555. Aroma-producing group ‘N’ streptococci isolated from Cheddar cheese curd

Abstract

A high proportion of the group ‘N’ streptococci, isolated from Cheddar cheese curd, produced volatile acids and acetoin, in varying degrees, in milk culture. The active acetoin-producing strains closely resembled type strains of Str. diacetilactis (Matuszew-ski) and Str. citrophilus P.R.M. but differed from them in producing acetoin in lactose broth. The weak acetoin-producing strains resembled Str. cremoris HP in this characteristic, but in their morphological and cultural reactions, mor e closely resembled Str. lactis. The titratable acidity in milk cultures varied inversely with the production of volatile acids and acetoin.