Rheological and physical characteristics of non-fat set yogurt prepared with EPS-producing Streptococcus thermophilus and an H+-ATPase-defective mutant Lactobacillus delbrueckii subsp. bulgaricus

Abstract

The rheological and physical characteristics of non-fat set yogurt produced using co-cultures of ropy EPS-producing Streptococcus thermophilus S3.3 and Lactobacillus delbrueckii subsp. bulgaricus LTM and of Streptococcus thermophilus S3.3 and Lactobacillus delbrueckii subsp. bulgaricus H+-ATPase-defective mutant L6 under different conditions were studied. Yogurts produced with mutant L6 had a higher pH and water-holding capacity and better textural properties compared to those produced with the LTM strain. The highest storage modulus (G′) and thixotropic loops were found for yogurt made with L6 at 42°C on day 21 of cold storage. This yogurt contained a network of thick, continuous protein aggregates and large void spaces.