Influence of sweetener type on growth, activity, and viability of yogurt cultures

Three different floral sources of honey (sage, alfalfa, sourwood) were compared to sucrose, high fructose corn syrup (HFCS) and inulin in their ability to support growth, activity and viability of yogurt cultures: Streptococcus salivarius subsp. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus acidophilus, and Bifdobacterium bifidum. The effect of yogurt ingredients on cultures was also investigated. A consumer panel determined sensory attributes of the product. Viability of lactic acid bacteria (LAB) and bifidobacteria in yogurt was investigated during 42 d of refrigerated storage. Each culture underwent three successive 24 h transfers at 37°C in MRS or MRSL media. Subsequently, the cultures were resuspended in 12% non-fat dry milk and 5 or 10% (w/v) of each sweetener was added. Controls were devoid of sweetener. Each sample was inoculated with 5% (v/v) cultures listed above and incubated (37°C/24 h). Overall, growth of LAB and bifidobacteria were enhanced in the presence of honey in a similar manner to HFCS particularly at 10% sweetener level. Yogurt ingredients had no inhibitory effect on growth of cultures. Sensory evaluation showed consumers' preference for sucrose and HFCS rather than honey. Viability of LAB and bifidobacteria was retained above 85% and 90% respectively for all treatments with the exception of yogurt sweetened with sourwood honey.