In vitro fermentation characteristics of two mushroom species, an herb, and their polysaccharide fractions, using chicken cecal contents as inoculum.

In vitro fermentabilities of two mushrooms (Lentinus edodes--LenS; Tremella fuciformis--TreS), an herb (Astragalus membranaceus--AstS), and their polysaccharide fractions (LenE, TreE, and AstE) were investigated using microflora from chicken ceca. Polysaccharides were extracted using the hot water method. The mushrooms had lower polysaccharide yields (8 to 10%) than the herb (31%). Fermentation kinetics were determined using the in vitro cumulative gas production technique. End-products, such as gas, volatile fatty acids (VFA), and ammonia, were also determined. The gas profiles of intact materials were similar for AstS and LenS. The TreS had a diphasic digestion pattern. The extracts had similar profiles to the intact materials though gas production rates were faster. Intact materials tended to produce less VFA than the extracts though LenS and AstE had the highest total VFA production overall. Intact materials contained more protein than the extracts, and therefore resulted in more branched-chain fatty acids and ammonia. Fermentation kinetics and end-point products demonstrated differences in availability of substrates between the mushrooms and herb. These medicinal mushroom and herb materials, particularly their polysaccharide extracts, show promise in altering microbial activities and composition in chicken ceca. In vivo experiments are necessary for confirmation of this hypothesis.