(PTFS10-02-24) Microbial Inulinase Promotes Fructan-Type FODMAP Hydrolysis From Wheat-Based Foods Under Simulated Oro-Gastric Conditions In Vitro

Objectives: The prevalence of non-allergic food intolerance is estimated to be up to 45% according to published surveys and clinical trials. One example is gastrointestinal (GI) sensitivity to fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) such as plant fructans—oligo- and polysaccharides largely comprised of the hexose sugar fructose. Fructans are resistant to human pancreatic enzymes, yet metabolized by intestinal microorganisms. To complement previous work on non-wheat substrates (e.g., garlic, onion), the objective of this study was to test the effects of microbial inulinase from Aspergillus tubingensis on hydrolyzing fructans from wheat-based foods in the INFOGEST static simulation of oro-gastric digestion.

Methods: INFOGEST simulations included a 2-min oral phase with porcine amylase and a 120-min gastric phase with porcine pepsin. Substrates included whole wheat couscous (Bob’s Red Mill®) and wheat farina (Cream of Wheat®). Free fructose concentrations and hexooligosaccharide (HOS) profiles of gastric digestas were measured by HPLC and LC-MS, respectively, to examine fructolytic activity. All simulations were performed in triplicate, and fructose concentrations are reported in mg fructose per g substrate.

Results: In simulated digestions of couscous, treatment with 5 doses of inulinase [125, 250, 500, 1000, and 1500 inulinase activity units (INU)] showed significant increases in gastric digesta fructose concentrations compared to control at all doses tested (all P < 0.0001), up to an 11.6-fold increase at 1,500 INU (3.82 vs. 0.32 mg/g, P < 0.0001). Simulated digestion of wheat farina showed significant increases in gastric digesta fructose concentrations compared to control at 125 INU and above (all P < 0.0001), up to a 5.7% increase at 1,500 INU (1.49 vs. 0.26 mg/g, P < 0.0001). LC-MS analysis of gastric digestas following simulated digestion of wheat farina showed increasing amounts of HOS with degree of polymerization 3 and higher (≥ DP3) with successively higher doses of inulinase, consistent with inulinase-mediated hydrolysis of high molecular weight hexans such as fructans.

Conclusions: These data demonstrate effective fructolytic activity of microbial inulinase toward wheat-based foods under physiologic gastric conditions in vitro and warrant further study in the context of FODMAP intolerance.

Funding Sources: BIO-CAT, Inc.