Use of Galactose-Fermenting Streptococcus thermophilus in the Manufacture of Swiss, Mozzarella, and Short-Method Cheddar Cheese

Abstract

Galactose-fermenting (galactose-positive) strains of Streptococcus thermophilus, alone and combined with galactose-positive and galactose-negative strains of Lactobacillus bulgaricus, were used as starter cultures in the manufacture of Swiss and Mozzarella cheese and were paired with Streptococcus lactis (also galactose-positive) in short-method Cheddar cheese manufacture. Experimental Swiss cheese made with the galactose-positive Streptococcus thermophilus starter alone contained a large amount of galactose (ca. 26 to 28 µmol/g of curd) 28h after hooping compared with control Swiss (< 2 µmol/g) made with a nongalactose fermenting strain of Streptococcus thermophilus and a galactose-positive strain of Lactobacillus bulgaricus. Mozzarella and short-method Cheddar made with only galactose-positive Streptococcus thermophilus also contained large amounts of galactose. Swiss cheese made with a galactose-positive strain of Streptococcus thermophilus and a galactose-negative strain of Lactobacillus bulgaricus had little galactose remaining after 28h, indicating that the Lactobacillus had a stimulatory effect on galactose metabolism in Streptococcus thermophilus. These results indicate that galactose-fermenting Streptococcus thermophilus may have limited potential when used as single strain starter cultures in Swiss cheese, but may be useful when combined with galactose-positive Lactobacillus in the manufacture of Mozzarella cheese.