Faster Fermentation of Cooked Carrot Cell Clusters Compared to Cell Wall Fragments in Vitro by Porcine Feces

Abstract

Plant cell walls are the major structural component of fruits and vegetables, which break down to cell wall particles during ingestion (oral mastication) or food processing. The major health-promoting effect of cell walls occurs when they reach the colon and are fermented by the gut microbiota. In this study, the fermentation kinetics of carrot cell wall particle dispersions with different particle size and microstructure were investigated in vitro using porcine feces. The cumulative gas production and short-chain fatty acids (SCFAs) produced were measured at time intervals up to 48 h. The results show that larger cell clusters with an average particle size (d(0.5)) of 298 and 137 μm were more rapidly fermented and produced more SCFAs and gas than smaller single cells (75 μm) or cell fragments (50 μm), particularly between 8 and 20 h. Confocal microscopy suggests that the junctions between cells provides an environment that promotes bacterial growth, outweighing the greater specific surface area of smaller particles as a driver for more rapid fermentation. The study demonstrates that it may be possible, by controlling the size of cell wall particles, to design plant-based foods for fiber delivery and promotion of colon fermentation to maximize the potential for human health.

In vitro fermentation of chewed mango and banana: particle size, starch and vascular fibre effects

“…6 It appears that the plant cellular composition or architecture has a more significant impact than particle size or available surface area (exposed to the faecal microbiota). Larger banana particles may have contained a higher proportion of more fermentable cell wall structures.…”

“…6), 26 followed by in vitro gastrointestinal digestion 6 and centrifugation at 3000g for 10 min (Avant®JE centrifuge, JA14 rotor). 6), 26 followed by in vitro gastrointestinal digestion 6 and centrifugation at 3000g for 10 min (Avant®JE centrifuge, JA14 rotor).…”

“…[5][6][7][8][9] The volume of gas produced as a result of fermentation acts as an indicator of potential fermentability of the substrate in response to a controlled microbial population. [5][6][7][8][9] The volume of gas produced as a result of fermentation acts as an indicator of potential fermentability of the substrate in response to a controlled microbial population.…”

Food Structure and Carbohydrate Digestibility

“…Paradoxically, multicellular clumps of carrot cells were found to be more rapidly fermented than cell wall fragments, probably because the intercellular spaces and angles between cells in multicellular clusters provided colonization sites for colonic bacteria (Day et al 2012). There is, however, likely to be an optimal size at which increased colonization sites are counterbalanced by inaccessibility in large particles.…”

Fibrous Cellular Structures are Found in a Commercial Fruit Smoothie and Remain Intact during Simulated Digestion

“…These cellular structures remained visually intact during in vitro colonic fermentation with smaller particles (<1 mm) fermenting more rapidly that larger ones. In contrast, fermentation of carrot cell clusters showed that particles measuring approximately 150-300 µm were more rapidly fermented than smaller clusters or single cells [9]. These studies suggest that the intactness of cellular structures may affect fruit and vegetable functionality in the gut.…”