Estimation of the fermentability of dietary fibrein vitro: a European interlaboratory study

Abstract

Five European laboratories tested a simple in vitro batch system for dietary fibre fermentation studies, The inoculum was composed of fresh human faeces mixed with a carbonatephosphate buffer complex supplemented with trace elements and urea. Five dietary fibre sources (cellulose, sugarbeet fibre, soyabean fibre, maize bran and pectin) were used by each laboratory on three occasions to determine pH, residual non-starch polysaccharides (NSP) and short-chain fatty acid production during fermentation. Cellulose and maize bran degradabilities were very low (7.2 (SE 10.8) and 6 2 (SE 9.1) % respectively after 24h), whereas pectin and soyabean fibre were highly degraded (97.4 (~~4 . 4 ) and 91.1 ( s~3 . 4 ) % respectively after 24 h). Sugarbeet fibre exhibited an intermediate level of degradability (595 (SE 149) %). Short-chain fatty acid production was closely related to NSP degradation (r 0.99). Although each variable was ranked similarly by all laboratories, some differences occurred with respect to absolute values. However, the adaptation of donors to the experimental substrates was not an influential factor. Interlaboratory differences could be reduced either by adding less substrate during incubations or using less-diluted inocula. In vitro fermentations with inocula made from human faeces and from rat caecal contents gave similar results. There was a close correspondence between the data obtained in the present experiment and those previously published in in vivo studies in the rat using the same fibres. The in v i m batch system tested during the present study provides a rapid means of obtaining quantitative estimates of the fermentation and the estimation of the energy content of new sources of dietary fibre.

Mechanisms of action of β-glucan in postprandial glucose metabolism in healthy men

“…First, the presence of ®bers may actually prevent the digestion and absorption of part of the ingested carbohydrate (Tsuji et al, 1992;Jenkins et al, 1987). Second, soluble ®bers (and any unabsorbed carbohydrate) will be fermented by the bacterial¯ora in the large intestine, thus releasing short chain fatty acids (acetate, propionate, butyrate) (Barry et al, 1995) which may be absorbed into the systemic circulation and exert metabolic effects. It may be hypothesized that such compounds may decrease postprandial glycemia by inhibiting endogenous glucose production or by increasing extrahepatic insulin actions.…”

Bebida à base de flocos de abóbora com inulina: características prebióticas e aceitabilidade

“…Para avaliar o efeito prebiótico foi realizada a fermentação das três formulações segundo a metodologia proposta por Barry et al 13 e Cambrodón & Martín-Carrón 14 . No processo de fermentação, as amostras pesando 100mg foram colocadas em tubos de ensaio com 8mL do meio de fermentação 13 , incubadas a 37ºC, em jarra de Gaspak com sistema anaeróbico, durante 12 horas.…”

“…No processo de fermentação, as amostras pesando 100mg foram colocadas em tubos de ensaio com 8mL do meio de fermentação 13 , incubadas a 37ºC, em jarra de Gaspak com sistema anaeróbico, durante 12 horas. Posteriormente, a cada tubo de ensaio foram adicionados 2mL do inóculo, preparado a partir de fezes de lactentes suspensas no meio de fermentação, elaborado segundo Barry et al 13 , na proporção de 10mL/g de fezes, incubadas a 37°C, sob anaerobiose durante 12 horas. Os tubos foram mantidos em sistema anaeróbico, em banho-maria com agitação e temperatura controlada a 37°C, permanecendo nessas condições durante o período de fermentação.…”

Chicory increases acetate turnover, but not propionate and butyrate peripheral turnovers in rats

“…[1-14 C]acetate, Na salt (50 mCi), [1-14 C]propionate, Na salt (250 mCi) and [1-14 C]butyrate, Na salt (50 mCi) were purchased from NENe Life Science Products, Inc. (Boston, MA, USA). [1,[2][3][4][5][6][7][8][9][10][11][12][13] C 2 ]acetate, [1][2][3][4][5][6][7][8][9][10][11][12][13] C]acetate, [1-13 C]propionate and [1-13 C]butyrate Na salt tracers were purchased from Cambridge Isotope Laboratories (Andover, MA, USA). A conventional diet was used in experiments 1 and 2, which contained 23·5 % protein, 5·5 % fat, 52 % carbohydrate and 3 % fibre (Kliba 3310; Promivi Kliba SA, Kaiseraugst, Switzerland).…”

“…After the last feeding by oral administration, the catheters were inserted under anaesthesia and a first arterial blood sample was collected (800 ml). Each rat was then administered, intravenously, a primed continuous infusion of [1,[2][3][4][5][6][7][8][9][10][11][12][13] C 2 ]acetate, [1-13 C]propionate and [1-13 C]butyrate simultaneously (all tracers solubilised in 0·9 % NaCl sterile solution; 287 (SEM 5), 97 (SEM 2) and 49 (SEM 1) mmol/kg priming doses and 2·84 (SEM 0·04), 0·96 (SEM 0·01) and 0·48 (SEM 0·01) mmol/kg per min infusion rates, respectively). Arterial blood samples (800 ml) were collected at 60, 75, 90, 105 and 120 min.…”