Abstract
Yogurt is one of the main food products that contain probiotic bacteria. Probiotic bacteria should be of not less than log 8 Colony-forming unit per ml (CFU/ml) in yogurt products to be effective as probiotic product. The objectives of this study were to investigate the initial enumeration and the viability of probiotic bacteria in the yogurt marketed in Saudi Arabia under refrigerated storage conditions. Twenty yogurt samples were collected and stored in 4 degrees C, and then enumeration was conducted using the specific growth agar for the probiotic bacteria. In addition, pH measurements and water holding capacity were conducted. The results of this study showed that the initial enumeration of both S. thermophilus and Lactobacillus delbrueckii spp. Bulgaricus was higher than log 8 CFU/ml in all the commercial products studied. However, the initial enumeration of bifidobacteria was considerably low (0.8-4.5 log CFU/ml) in all the commercial products studied. Viability of both S. thermophilus and Lactobacillus delbrueckii spp in all commercial products slightly decreased during the 4-week refrigeration period. However, the viability of bifidobacteria in the commercial products was slightly decreased up to 3 weeks of recreation. In week 4, the viability of bifidobacteria in all the commercial products studied was drastically decreased. Different techniques should be adopted to improve the initial enumeration of bifidobacteria in commercial yogurt products and to improve its viability during storage conditions. (C) 2020 The Authors. Published by IASE.