Abstract
Colonic fermentation of resistant starch provides health benefits to the host. However, physical characteristics of the food matrix could limit the availability of starch and other dietary fibres for microbiota utilization. In this study, the influence of food structural aspects was studied by using cotyledon cells from red kidney beans with different levels of cellular integrity. In-vitro colonic fermentation was conducted in the simulator of the human intestinal microbial ecosystem (SHIME®) where the utilization of starch and other non-starch polysaccharides was investigated along the three colon regions. Results indicate that plant cell integrity modulates nutrient utilization by gut microbiota where higher amounts of starch were delivered to distal regions of the colon in intact samples. Other dietary fibre constituents, such as pectin, were also differentially fermented depending on the level of cellular integrity. Moreover, bean supplementation produced changes in microbiota population favouring the proliferation of Bifidobacterium species.
Highlights
Colonic fermentation of carbohydrates provides beneficial physiological effects for human health (Sonnenburg & Sonnenburg, 2014)
As seen in the figure, AC was the portion with the highest levels of unfermented starch, followed by transverse colon (TC) and descending colon (DC) independently of the treatment considered (ICC, Mechanically damaged cells (MDC))
For Intact cotyledon cells (ICC) samples, large amounts of unfermented starch were recovered in AC during the first 6 days of fermentation, where nearly 30% of the feed collected was constituted by starch
Summary
Colonic fermentation of carbohydrates provides beneficial physiological effects for human health (Sonnenburg & Sonnenburg, 2014). Non-digestible polysaccharides, commonly known as dietary fibre, are the primary source of carbon and energy for gut microbiota which favours bacterial diversity (Sonnenburg et al, 2016), production of gas, organic acids and short chain fatty acids (SCFA) (Hernández-Salazar et al, 2010; Slavin, 2013). It has been found that dietary fibres are not fermented by the gut microbiota and a hierarchic order is followed where simple sugars, oligosaccharides and starch are preferred over soluble and insoluble non-starch polysaccharides (NSP) (Bach Knudsen, 2015). It has been shown that the presence of RS delays the fermentation of other non-starch polysaccharides towards distal parts of the colon (Jonathan et al, 2013) thereby decreasing protein fermentation which has been shown to produce toxic compounds such as ammonia, phenols, amines, thiols and branched chain fatty acids. The amount of RS in the diet will vary depending on food composition, structure and the cooking methods applied
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