No abstract

This study focuses on the development of an in vitro digestion model simulating oral, gastric and small intestinal fluids, applicable to the digestion of all three macronutrients, carbohydrates, proteins and lipids. To that aim, the effect of integrating intestinal mucosal enzymes in the small intestinal phase of the digestion reaction was investigated, together with that of other parameters including pepsin and pancreatin concentration, and pH of the small intestinal phase. Individual carbohydrate and protein ingredients for which digestive properties in vivo are generally understood (i.e. common corn starch, whey protein isolate) were used as reference substrates to validate the model and, at the end of development, the model was applied to evaluate the digestion of a reference lipid ingredient (i.e. olive oil) and of all three macronutrients present in a whole food system. Carbohydrate, protein and lipid hydrolysis was monitored, respectively, by quantitation of glucose, free amino groups and free fatty acids released at different times of digestion. The results demonstrate that including intestinal mucosal enzymes in the intestinal phase of digestion in vitro allows efficient digestion of starch and other carbohydrates into final product glucose and it also influences protein hydrolysis. Digestion profiles consistent with published in vitro and in vivo data support the validity of the developed method as an advanced tool for screening digestion of all three macronutrients whether presented alone or in a whole food system, all in a single digestion reaction.

Formulation and processing can improve nutritional, functional, and health attributes of foods. In breads, addition of whole wheat (WW) enhances content of dietary fiber, proteins, and non‐nutrients: minerals and antioxidants. Bioaccessibility of these compounds is partial due to cross‐linking to polymers and/or physical entrapment within the complex plant cell wall matrix and can be improved by technological processes. We study the effect of two bioprocessing techniques: A) Enzyme (pre‐ vs in situ treatment), B) dough mixing method (straight vs sponge and dough), in the release of antioxidants (free Ferulic Acid (FA) and Steryl Ferulates), in vitro digestibility, and antioxidant bioaccessibility in WW or Aleurone‐containing WW (AL‐WW) breads. Sponge and‐dough processing and enzyme treatment increases 1.5‐4.0 times the free FA in AL‐WW breads but only in‐situ enzyme treatment enhances free FA (about 1.4 times) in WW breads. Free Steryl Ferulates also increased with both processing methods in AL‐WW breads. Straight dough but not enzyme treatment enhances in vitro digestibility of AL‐WW bread starch fractions while the combination of sponge time and enzyme treatment benefit in vitro digestibility of WW bread. Bioaccessibility of antioxidant compounds (ORAC) is higher in AL‐WW vs WW bread. Thus, nutritional properties and health benefits of bread are influenced by formulation and processing techniques.

Enhancing overall health status through nutrition has growing interest in humans and animals and thus, the market for food and feed formulations with added functional dietary ingredients is on the rise. Health‐promoting properties of wheat are documented in vivo and in vitro, and are partially attributed to antioxidant compounds in the bran fraction. Cargill isolates the aleurone fraction from wheat bran which is used as an ingredient in companion animal diets with the expectation of promoting a healthier diet. However, for bioactive compounds to be efficacious, they must be bioaccessible (available for absorption) during the digestive process. Our studies indicated antioxidants from aleurone are more bioaccessible than those from beet pulp fiber (BP) in an in vitro dynamic digestive system (TNO) validated for the GI‐tract of dogs. Results show low molecular weight antioxidant compounds become bioaccessible in the jejunum compartment of the small intestine but not in the ileum (TIMdog‐1), and antioxidant activity is comparable among the substrates. Furthermore, additional antioxidant compounds are released during fermentation (lower GI, TIMdog‐2) of the non‐digested fraction, with cumulative antioxidant activity being about 25% higher from aleurone than BP. Thus, supplementing pet food with wheat aleurone fractions may be a strategy for improved health benefits in a canine diet.

Objectives To evaluate the bioaccessibility of bioactive compounds present in Corn Bran using an in vitro gastrointestinal digestion model and to explore reducing particle size as a strategy to modify bioaccessibility. Methods Corn Bran (coarse and cryoground) was submitted to an in vitro digestion model of the upper gastro-intestinal tract. Supernatants of samples taken at different times of gastric and small intestinal digestion were analyzed by LC-MS to quantify phenolic acids and phytosterols. Undigested materials were acid hydrolyzed for 4 hours at room temperature and bioactive compounds quantified by LC-MS. Particle size and cell integrity of study materials were analyzed by Malvern Mastersizer 3000 Laser Light Diffraction Particle Size Analyzer and SEM, respectively. Results Average particle size of undigested coarse and cryoground Corn Bran materials was 645 μm and 62 μm, respectively. Microscopy revealed a very significant breakup of the cells in the cryoground material. LC-MS analysis confirmed high abundance of phenolic acids and phytosterols. There was minimal impact of particle size on in vitro bioaccessibility of most bioactive compounds tested. However, distinct bioaccessibility responses were observed. The release of phenolic acids happened during the small intestinal phase and it increased with time of digestion. The most abundant phenolic acid in Corn Bran, ferulic acid, showed very low bioaccessibility (<2%) at the end of digestion, likely representing the free (non-bound) fraction. Comparatively, higher release at end of digestion, was observed for coumaric (∼35%), vanillic (∼25%), sinapic and caffeic (both at around 20%) acids, and bioaccessibility of syringic acid was about 7%. In contrast, for Phytosterols (Campestanyl ferulate and Oryzanol-Campesteryl ferulate) about 60% release was observed at very early stages of the small intestinal digestion, and less than 20% release was measured at end of digestion which suggests chemical instability and/or transformation of these compounds in the digestion reaction. Conclusions In vitro bioaccessibility assessment of phytochemicals in Corn Bran demonstrated distinct release responses for different classes of compounds, indicating that the breakdown of digestive components of the Corn Bran matrix by the host enzymes differently impacts the rate of release. Funding Sources Cargill Inc.