Textural properties and survival of Lactobacillus acidophilus, streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus of probiotic set yogurts produced by prebiotic stabilizers and different molasses types

Abstract

Set type probiotic yogurts were prepared by the addition of three types of molasses (grape, mulberry and carob) at the rate of 100 ml L-1 and two types of prebiotic stabilizers (pectin and guar gum) at the rate of 5 g L-1. The pH, whey separation, textural properties (firmness, consistency, cohesiveness and index of viscosity) and survival of Lactobacillus acidophilus, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus were evaluated during 14-day storage period. The pH values were not influenced by molasses types and stabilizer addition. Pectin-added yogurts had lower values than yogurts without stabilizers. No whey separation was observed in guar-added yogurts containing different molasses types. Stabilizer addition influenced textural properties of yogurts. Firmness and consistency values of yogurts were increased by pectin addition but decreased by the addition of guar gum. Guar gum addition also decreased cohesiveness and index of viscosity values of yogurts. The viable counts of L. acidophilus, S. thermophilus and L. delbrueckii subsp. bulgaricus in all yogurts were above 8 log cfu g-1 during storage period. Molasses types and stabilizer addition did not influence the counts of bacteria. Survival of starter and probiotic bacteria were not negatively affected by molasses addition.