Viability of Bifidobacteria Strains in Yogurt with Added Oat Beta‐Glucan and Corn Starch during Cold Storage

Abstract: Probiotics must be consumed at a level of 10 7 CFU/mL for successful colonization of the gut. In yogurts containing beneficial cultures, the survival of probiotic strains can quickly decline below this critical concentration during cold storage. We hypothesized that beta‐glucan would increase the viability of bifidobacteria strains in yogurt during cold storage. Yogurts were produced containing 0.44% beta‐glucan (concentrated or freeze‐dried) extracted from whole oat flour and/or 1.33% modified corn starch, and bifidobacteria ( B. breve or B. longum ) at a concentration of at least 10 9 CFU/mL. All yogurts were stored at 4 °C. Bifidobacteria and yogurt cultures, Streptococcus thermophilus and Lactobacillus delbureckii subsp. bulgaricus , were enumerated from undisturbed aliquots before fermentation, after fermentation, and once a week for 5 wk. S. thermophilus and L. bulgaricus maintained a concentration of at least 10 8 CFU/mL in yogurts containing concentrated or freeze‐dried beta‐glucan regardless of starch addition, and in the control with no added beta‐glucan or starch. Similarly, the probiotic, Bifidobacterium breve , survived above a therapeutic level in all treatments. The addition of beta‐glucan prolonged the survival of Bifidobacterium longum at a concentration of at least 10 7 CFU/mL by up to 2 wk on average beyond the control. Further, the inclusion of concentrated beta‐glucan in yogurt improved survival of B. longum above 10 7 CFU/mL by 1 wk longer than did freeze‐dried beta‐glucan. Study results suggest that beta‐glucan has a protective effect on bifidobacteria in yogurt when stressed by low‐temperature storage. Practical Application: This study suggests that beta‐glucan (oat fiber) may improve bifidobacteria survival in yogurt during refrigerated storage.