Model experiments mimicking the human intestinal transit and metabolism of D‐galacturonic acid and amidated pectin

Abstract

In order to study the human intestinal transit and metabolism of D-galacturonic acid and amidated pectin a number of model experiments were carried out. Both substrates were incubated under aerobic conditions at 37 degrees C using saliva (2 min) and simulated gastric juice (4 h). Under anaerobic conditions the substrates were incubated at 37 degrees C using human ileostomy and colostomy fluids, each obtained from three different donors, for 10 and for 24 h, respectively. D-Galacturonic acid, SCFA (acetic acid, propionic acid, and butyric acid), as well as methanol were analyzed photometrically after carbazole reaction, GC-flame ionization detection (GC-FID), and headspace solid-phase microextraction GC/MS (HS-SPME-GC/MS), respectively. D-Galacturonic acid and amidated pectin were found to be stable during incubations with saliva and simulated gastric juice, whereas both substrates underwent degradation in the course of human ileostomy and colostomy fluid incubations. D-Galacturonic acid was practically completely decomposed within 10 h and SCFA, with acetic acid as the major representative, were formed up to 98% of the incubated substrate in colostomy effluent. The amidated pectin was only degraded in part, revealing stable amounts of 22-35% and 3-17% in ileostomy (after 10 h) and colostomy fluid (after 24 h), respectively. SCFA were generated up to 59% of the applied amidated pectin. In parallel, 19-60% and 52-67% of the available methyl ester groups were cleaved in the course of incubations with ileostomy and colostomy fluids, respectively. The results demonstrate for the first time that D-galacturonic acid and amidated pectin are stable in human saliva and simulated gastric juice. The degradation of both compounds during incubation with ileostomy effluent is highlighted, providing evidence for a considerable metabolic potential of the small intestine.

Non‐digestible oligosaccharides modulate intestinal immune activation and suppress cow's milk allergic symptoms

“…Currently, it is unknown whether addition of pAOS to GF results in alterations of the microflora which could contribute to differential immune activation of the intestinal mucosa. Indeed, one of the known functions of pAOS is that it can be fermented by luminal bacteria and acts as receptor analogue to inhibit adhesion of pathogens . Alternatively pAOS may have interfered directly with the immune cells .…”

Preparation and characterization of shellac‐coated anthocyanin pectin beads as dietary colonic delivery system

“…In the in vitro and ex vivo model system applied here for studying release properties, the effect of the enzymatic activity of human intestinal microbiota on the formulations' degradation is checked using IF and CF. These media have previously been shown to represent a reliable model to mimic human intestinal metabolism [26,40]. Thus, to simulate the transit of human stomach, ileum and colon APB were incubated 3 h in SGF (pH 2.0), 4 h in IF (pH 6.3) and, finally, 15 h in CF (pH 6.2).…”

“…Therefore, beads were incubated 3 h in SGF (pH 2.0), 4 h in IF (pH 6.3) and, finally, 15 h in CF (pH 6.2). IF and CF have been shown to represent a reliable model to mimic human intestinal metabolism [26,40]. Incubation times were chosen according to transit times in the human GIT [41].…”

“…As amidated pectin is not metabolized by endogenous digestive enzymes, it is stable in saliva and gastric juice. In the terminal ileum, slight degradation is found due to microbial activity, but the main part of the polymer reaches the colon where it is completely degraded by the microbiota [25][26][27]. Eubacterium eligens and Bacteroides thetaiotaomicron being potential members of the microbiota able to degrade amidated pectin [28,29].…”

25 Years Food Chemistry and Toxicology at the University of Kaiserslautern

“…Hydrolysis of polyphenol glucosides depended on the microflora and was abrogated by application of antibiotics [28]. An ex vivo ileo-/colostoma model was introduced as a promising tool to further investigate the intestinal transit and metabolism of various physiologically active compounds [29]. Another contribution presented evidence that a diet rich in products of the Maillard reaction was protective against Low Density Lipoprotein oxidation [30].…”