Effects Of Probiotics And Tea Polyphenols On Acids Production During The Simulated Colonic Fermentation Of Two Dietary Fibers

Resistant starch (RS), konjac glucomannan (KGM), probiotics, and polyphenols all have health-promoting effects. RS and KGM are dietary fibers that cannot be digested in the small intestine but fermented by the intestinal flora in the large intestine. In the present study, RS and KGM were used as two substrates, and fermented by healthy adult fecal extract under the stimulated conditions of the large intestines to quantify the levels of three short chain fatty acids (SCFAs; acetic, propionic and butyric acid) and lactic acid in the fermentation system. Exogenous probiotics were added into fermentation system to assess the possible interactions between probiotics and acids production. At the same time, mixed probiotics and direct-vat-starter (DVS) were also added into fermentation system of RS to shows their effects on acids production. Moreover, tea polyphenols was applied in the RS and KGM fermentation system to investigate its effects on acids production. The main results are listed as below.(1) When RS and KGM were fermented by fecal extract at12and9g·L-1,37℃for0-48h respectively, only acetic, butyric and lactic acids (but not propionic acid) generated from RS were significantly increased, while those acids generated from KGM was all significantly increased.(2) When RS was fermented by fecal extract and exogenous probiotics, it was found that Bifidobacterium infantis increased acetic acid production by198%, Lactobacillus brevis and B. infantis increased propionic acid production by554%, B. longum, B. infantis, Enterococcus faecalis increased butyric acid production by216%, while E. faecalis increased lactic acid production by58%.(3) When KGM was fermented by fecal extract and exogenous probiotics. L. brevis, L. helveticus, L. casei and Streptococcus thermophilus increased acetic acid production by143-227%, L. brevis increased propionic and butyric acid production by187%and347%, respectively, while E. faecalis decreased lactic acid production by40%.(4) When RS was fermented by fecal extract and mixed exogenous probiotics, the added mixed probiotics had different impacts on acids production. Two probiotics strains with lower ability to enhance acetic and propionic acids production could bring about a synergic effect on two acids production significantly. On the contrary, two probiotics strains with better ability to enhance acetic and propionic acids did not result in a synergic effect. When two probiotics strains with better ability to enhance butyric and lactic acids production were used together, the production of two acids increased significantly.(5) When RS was fermented by fecal extract and one DVS, the kinds of DVS had impacts on the production of four acids. DVS showed weaker capacity on acids production than added exogenous probiotics or mixed probiotics.(6) When RS and KGM were fermented by fecal extract and exogenous probiotics, tea polyphenols added into fermentation system could facilitate lactic acid production but inhibit acetic, propionic and butyric acids production. The probiotics inoculated could weaken the inhibitory effects of tea polyphenols on acids production, which resulted in enhanced acetic, propionic and butyric acids production but decreased lactic acid production.It was thus concluded that exogenous probiotics and tea polyphenols had effects on in vitro colonic fermentation of RS and KGM, resulting in modified production profiles of four organic acids (acetic, propionic, butyric and lactic acids) in fermentation system.