Supplementary Table 1: Effects of kefir fermented with or without 1% autolyzed yeast powder on dry matter intake, intestinal permeability, and rumen fermentation profile of Holstein calves.
Description
The water-soluble exopolysaccharide kefiran, which is responsible for the structure of kefir grains and the physicochemical properties of kefir has been identified as a potential source of bioactive components. Exopolysaccharides have been evaluated as prospective drug delivery vehicles, edible food coverings, and natural alternatives to antimicrobials. However, large-scale production of kefiran proves to be difficult and inefficient due to the complexities of fermentation. Addition of certain strains of Saccharomyces cerevisiae (SC) to kefir during fermentation can improve kefiran production under aerobic conditions compared to kefir grains fermented alone. To determine a more approachable and cost-effective approach to enhancing kefiran production in kefir, and an appropriate inclusion rate for use in an on-farm setting, evaluation of commercially available, food-grade distiller’s yeast and autolyzed yeast powder on kefiran yield was performed. Four different concentrations of SC on a weight-by-weight basis (w/w; g of SC per 20 g of kefir grain). Concentrations of 0%, 0.25%, 0.50%, and 1% were evaluated. Live dried, activated distiller’s yeast (DADY; Red Star; BSG Handcraft, Shakopee, MN) and dried autolyzed yeast powder (YP: MP Biomedicals, Santa Ana, CA) were evaluated at each concentration to determine which was the most effective in stimulating kefiran production. Fermentations with each inclusion level were performed in triplicate using whole, salable cow's milk. Exopolysaccharide production in kefir fermented with YP was improved compared with kefir fermented with DADY, with a 1% inclusion rate of YP yielding the most precipitate. Inclusion of autolyzed yeast powder during fermentation positively influenced EPS production and also increased amounts of viable Lactobacillus spp. in kefir compared to inclusion of dried, activated distiller’s yeast. Based on the results observed, and for ease of use for calculating YP inclusions in an on-farm setting, an inclusion rate of 1% YP was chosen for use in a field trial. The included table presents the means of fermentation data for kefir grains fermented with different concentrations of 0% (CON), dried, activated distiller’s yeast (DADY) or autolyzed yeast powder (YP).