Fruit and vegetable insoluble dietary fibre in vitro fermentation characteristics depend on cell wall type

• Published in: Bioactive carbohydrates and dietary fibre Vol. 23; p. 100223
• Main Authors: Widaningrum, Flanagan, Bernadine M., Williams, Barbara A., Sonni, Francesca, Mikkelsen, Deirdre, Gidley, Michael J.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2020
• Subjects: Cell walls; In vitro fermentation; Insoluble dietary fibre; Pig model; Short-chain fatty acids; Short-chain fatty acids; Pig model; In vitro fermentation; Cell walls; Insoluble dietary fibre
• ISSN: 2212-6198; 2212-6198
• DOI: 10.1016/j.bcdf.2020.100223

Dietary fibres (DF) are polysaccharides and their assemblies resistant to digestive enzyme hydrolysis in the stomach or small intestine. Upon reaching the large intestine, DF are fermented by gut microbes, generating end-products such as short-chain fatty acids (SCFA) which are useful for many metabolic functions associated with host health. Research to date has focussed on the fermentation of the soluble fraction of DF extracted from food plants, with less information available on the insoluble fraction (IDF). As nutritional benefits are obtained from the consumption of adequate quantities of DF including both soluble and insoluble fractions, a study to investigate fermentability of naturally occurring IDF from a range of fruits and vegetables was conducted. IDF from spinach, carrot, celery, apple, and banana were isolated by mincing and then subjected to washing processes to represent gastrointestinal digestion and remove soluble fibres. The remaining insoluble fibres were fermented in vitro with a well-defined faecal inoculum from pigs fed a controlled diet free of fruit and vegetables. All the IDF substrates were fermented extensively as reflected by gas and short chain fatty acid production. Apple was the most rapidly and completely fermented, followed by celery, carrot, spinach and banana. Fast fermentation was associated with higher levels of pectin and primary cell walls, whereas slower fermentation was associated with secondary (thickened) cell walls, starch and lignin. This work has indicated that the insoluble fractions of the fruit and vegetable fibres tested are highly (and variably) fermented, consistent with them making a significant contribution to gut fermentation. [Display omitted]