Streptococcus thermophilus as adjunct culture for a semi-hard cows' milk cheese

Abstract

The influence of the addition of Streptococcus thermophilus as adjunct to the mesophilic starter on chemical, textural and sensory characteristics of a semi-hard cows' milk cheese was studied. Addition of the thermophilic adjunct increased αs1-casein hydrolysis and the level of N soluble at pH 4.6 after 30 d of ripening, reduced the level of N soluble in TCA and did not affect the level of N soluble in PTA. Lower apparent elastic modulus, breaking force and hardness were recorded for cheeses with thermophilic adjunct, as a consequence of the lower dry matter and the slightly enhanced casein hydrolysis. Flavour quality, flavour intensity and cheese bitterness were not affected by S. thermophilus addition. In cheese made from milk with Bacillus subtilis neutral proteinase added to accelerate ripening and induce bitter flavour formation, the use of S. thermophilus as adjunct enhanced proteolysis and produced a considerably higher concentration of N soluble in PTA. Textural characteristics were not affected. Flavour quality was improved and cheese bitterness significantly reduced by the addition of the thermophilic adjunct. ©Inra/Elsevier, Paris.