Fermentation of the endosperm cell walls of monocotyledon and dicotyledon plant species by faecal microbes from pigs - The relationship between cell wall characteristics and fermentability

Cell walls from the endosperm of four monocotyledons (maize, wheat, rye, an d rice) and four dicotyledons (soya bean, lupin, faba bean, and pea) seeds were studied to relate cell wall composition and structure with fermentatio n characteristics. Cell wall material was isolated from the endosperm of th e mono- and dicotyledons. The fermentation characteristics of isolated cell walls from mono- and dicotyledons were analysed in two separate in vitro g as production experiments. At 0, 12, 24, 36, 48, and 144 h of fermentation, fermentation was stopped in selected bottles to analyse VFA production (14 4 h only) and sugar degradation patterns. The relationship between cell wal l characteristics (composition, particle size) and fermentation characteris tics (half-time of gas production acid maximal I ate of substrate degradati on) was analysed using linear regression. For the monocotyledon cell walls, the rate of substrate degradation was decreased by increasing particle siz e of the cell walls, a clear effect of cell wall composition on fermentatio n characteristics could not be determined, though this might have been obsc ured by the differences in particle size. During fermentation of the monoco tyledon cell wall, arabinoxylans (arabinose and xylose) and cellulose (gluc ose) appeared to be degraded simultaneously. For the dicotyledon cell walls , an increase in total sugar content decreased the half-time of gas product ion, though total sugar content was probably confounded with the crude prot ein content. During fermentation of the dicotyledon cell wall, pectins or p ectin-related sugars (galactose, arabinose, uronic acids) appeared to be de graded faster than cellulose, whereas for the monocotyledon cell walls, ara binoxylans and cellulose were degraded simultaneously. The differences in c ell wall fermentation and sugar degradation pattern between monocotyledon a nd dicotyledon cell walls are discussed in relation to differences in cell wall architecture. (C) 2000 Elsevier Science B.V. All rights reserved.