Viability of Lactobacillus delbrueckii subsp. bulgaricus in commercial yogurt products sold in North Carolina

Lactobacillus delbrueckii subsp. bulgaricus is a key bacterium in yogurt production, contributing to its smooth texture, viscous consistency, and tangy flavor. Its role is vital for developing the desirable sensory attributes of yogurt, including flavor, aroma, and texture, which define product quality. This research investigated the probiotic potential and viability of yogurt products sold in North Carolina. Out of 67 plain yogurt samples from 33 different brands, 14 were chosen for further analysis based on criteria including cost, sugar levels, and the claims listed on their packaging. The viability of L. delbrueckii subsp. bulgaricus was assessed using MRS and mRCM-pyruvate media. The results revealed that viable counts varied from 0 to 7.97 Log cfu/mL. Out of the 14 yogurt products tested, 7 displayed viable counts on MRS media, while 8 exhibited viability on mRCM-pyruvate media. Overall, the findings suggested that most yogurt products in North Carolina contained L. delbrueckii subsp. bulgaricus at levels below those stated on product labels. These outcomes raise concerns regarding the survivability of L. delbrueckii subsp. bulgaricus in commercial yogurts, which may impact the ability of these products to deliver the intended probiotic health benefits to consumers. Ensuring viable culture levels is essential for maintaining product quality and consumer trust.