Effect of degradation on the porosity and surface area of forage cell walls of differing lignin content

P T Gardner, T J Wood, A Chesson, T Stuchbury

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Cell walls, prepared from the stems of wheat, maize, lucerne and rape and from timothy grass, were degraded using a commercial cellulase enzyme preparation. Timothy and lucerne were extensively degraded (60-70% loss of dry matter) while dry matter losses from the more lignified maize, rape and wheat samples were substantially less (30-40%). Residues obtained after 6 and 72h degradation and original preparations were examined for pore structure and surface area by nitrogen adsorption. The pore regime of all of the samples fell within the range 0.5-5 nm radius with pores of 1-2nm radius predominating. Degradation had little impact on pore regimes or mean pore radius which were essentially the same as the starting material. The exception was timothy where the mean pore radius fell from 2.80 to 2.36 nm (P < 0.001) accompanied by a fall in available surface area (2.49 to 1.39m(2)g(-1) P < 0.001). Wheat showed a similar fall in available surface area after 72h degradation (3.29 to 2.49m(2)g(-1) P < 0.05) but no significant differences were seen in the remaining samples. In a separate experiment, effect of lignification on pore structure was examined using sequential sections taken from a newly extended maize internode. The phenolic content differed two-fold between the youngest and oldest sections and there was an accompanying steady decrease in electronegativity which weakly correlated with the phenolic content (r(2) = 0.504). Na significant differences were seen in pore volume, mean pore radius or pore regimes along the internode, but the available surface area increased significantly with maturity (P < 0.01) and was strongly correlated with the phenolic content (r(2) = 0.896). Since porosity is defined by the spacing between polymers of the wall, a considerable commonality of three-dimensional structure evidently existed amongst the cell walls of the plants examined which was little affected by lignification or degradation. This is consistent with exclusion of enzymes by the wall which ensures that bacterial attack in the rumen and elsewhere proceeds by a process of surface erosion. (C) 1999 Society of Chemical Industry.

Original languageEnglish
Pages (from-to)11-18
Number of pages8
JournalJournal of the Science of Food and Agriculture
Volume79
Publication statusPublished - 1999

Keywords

  • timothy grass
  • lucerne stem
  • wheat straw
  • maize internode
  • rape stem
  • cell wall
  • porosity
  • surface area
  • gas adsorption
  • enzymatic degradation
  • digestibility
  • PHYSICAL-PROPERTIES
  • SOLUTE EXCLUSION
  • PORE-SIZE
  • CELLULOSE
  • CHROMATOGRAPHY
  • DIGESTIBILITY
  • RUMEN

Cite this

Effect of degradation on the porosity and surface area of forage cell walls of differing lignin content. / Gardner, P T ; Wood, T J ; Chesson, A ; Stuchbury, T .

In: Journal of the Science of Food and Agriculture, Vol. 79, 1999, p. 11-18.

Research output: Contribution to journalArticle

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abstract = "Cell walls, prepared from the stems of wheat, maize, lucerne and rape and from timothy grass, were degraded using a commercial cellulase enzyme preparation. Timothy and lucerne were extensively degraded (60-70{\%} loss of dry matter) while dry matter losses from the more lignified maize, rape and wheat samples were substantially less (30-40{\%}). Residues obtained after 6 and 72h degradation and original preparations were examined for pore structure and surface area by nitrogen adsorption. The pore regime of all of the samples fell within the range 0.5-5 nm radius with pores of 1-2nm radius predominating. Degradation had little impact on pore regimes or mean pore radius which were essentially the same as the starting material. The exception was timothy where the mean pore radius fell from 2.80 to 2.36 nm (P < 0.001) accompanied by a fall in available surface area (2.49 to 1.39m(2)g(-1) P < 0.001). Wheat showed a similar fall in available surface area after 72h degradation (3.29 to 2.49m(2)g(-1) P < 0.05) but no significant differences were seen in the remaining samples. In a separate experiment, effect of lignification on pore structure was examined using sequential sections taken from a newly extended maize internode. The phenolic content differed two-fold between the youngest and oldest sections and there was an accompanying steady decrease in electronegativity which weakly correlated with the phenolic content (r(2) = 0.504). Na significant differences were seen in pore volume, mean pore radius or pore regimes along the internode, but the available surface area increased significantly with maturity (P < 0.01) and was strongly correlated with the phenolic content (r(2) = 0.896). Since porosity is defined by the spacing between polymers of the wall, a considerable commonality of three-dimensional structure evidently existed amongst the cell walls of the plants examined which was little affected by lignification or degradation. This is consistent with exclusion of enzymes by the wall which ensures that bacterial attack in the rumen and elsewhere proceeds by a process of surface erosion. (C) 1999 Society of Chemical Industry.",
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T1 - Effect of degradation on the porosity and surface area of forage cell walls of differing lignin content

AU - Gardner, P T

AU - Wood, T J

AU - Chesson, A

AU - Stuchbury, T

PY - 1999

Y1 - 1999

N2 - Cell walls, prepared from the stems of wheat, maize, lucerne and rape and from timothy grass, were degraded using a commercial cellulase enzyme preparation. Timothy and lucerne were extensively degraded (60-70% loss of dry matter) while dry matter losses from the more lignified maize, rape and wheat samples were substantially less (30-40%). Residues obtained after 6 and 72h degradation and original preparations were examined for pore structure and surface area by nitrogen adsorption. The pore regime of all of the samples fell within the range 0.5-5 nm radius with pores of 1-2nm radius predominating. Degradation had little impact on pore regimes or mean pore radius which were essentially the same as the starting material. The exception was timothy where the mean pore radius fell from 2.80 to 2.36 nm (P < 0.001) accompanied by a fall in available surface area (2.49 to 1.39m(2)g(-1) P < 0.001). Wheat showed a similar fall in available surface area after 72h degradation (3.29 to 2.49m(2)g(-1) P < 0.05) but no significant differences were seen in the remaining samples. In a separate experiment, effect of lignification on pore structure was examined using sequential sections taken from a newly extended maize internode. The phenolic content differed two-fold between the youngest and oldest sections and there was an accompanying steady decrease in electronegativity which weakly correlated with the phenolic content (r(2) = 0.504). Na significant differences were seen in pore volume, mean pore radius or pore regimes along the internode, but the available surface area increased significantly with maturity (P < 0.01) and was strongly correlated with the phenolic content (r(2) = 0.896). Since porosity is defined by the spacing between polymers of the wall, a considerable commonality of three-dimensional structure evidently existed amongst the cell walls of the plants examined which was little affected by lignification or degradation. This is consistent with exclusion of enzymes by the wall which ensures that bacterial attack in the rumen and elsewhere proceeds by a process of surface erosion. (C) 1999 Society of Chemical Industry.

AB - Cell walls, prepared from the stems of wheat, maize, lucerne and rape and from timothy grass, were degraded using a commercial cellulase enzyme preparation. Timothy and lucerne were extensively degraded (60-70% loss of dry matter) while dry matter losses from the more lignified maize, rape and wheat samples were substantially less (30-40%). Residues obtained after 6 and 72h degradation and original preparations were examined for pore structure and surface area by nitrogen adsorption. The pore regime of all of the samples fell within the range 0.5-5 nm radius with pores of 1-2nm radius predominating. Degradation had little impact on pore regimes or mean pore radius which were essentially the same as the starting material. The exception was timothy where the mean pore radius fell from 2.80 to 2.36 nm (P < 0.001) accompanied by a fall in available surface area (2.49 to 1.39m(2)g(-1) P < 0.001). Wheat showed a similar fall in available surface area after 72h degradation (3.29 to 2.49m(2)g(-1) P < 0.05) but no significant differences were seen in the remaining samples. In a separate experiment, effect of lignification on pore structure was examined using sequential sections taken from a newly extended maize internode. The phenolic content differed two-fold between the youngest and oldest sections and there was an accompanying steady decrease in electronegativity which weakly correlated with the phenolic content (r(2) = 0.504). Na significant differences were seen in pore volume, mean pore radius or pore regimes along the internode, but the available surface area increased significantly with maturity (P < 0.01) and was strongly correlated with the phenolic content (r(2) = 0.896). Since porosity is defined by the spacing between polymers of the wall, a considerable commonality of three-dimensional structure evidently existed amongst the cell walls of the plants examined which was little affected by lignification or degradation. This is consistent with exclusion of enzymes by the wall which ensures that bacterial attack in the rumen and elsewhere proceeds by a process of surface erosion. (C) 1999 Society of Chemical Industry.

KW - timothy grass

KW - lucerne stem

KW - wheat straw

KW - maize internode

KW - rape stem

KW - cell wall

KW - porosity

KW - surface area

KW - gas adsorption

KW - enzymatic degradation

KW - digestibility

KW - PHYSICAL-PROPERTIES

KW - SOLUTE EXCLUSION

KW - PORE-SIZE

KW - CELLULOSE

KW - CHROMATOGRAPHY

KW - DIGESTIBILITY

KW - RUMEN

M3 - Article

VL - 79

SP - 11

EP - 18

JO - Journal of the Science of Food and Agriculture

JF - Journal of the Science of Food and Agriculture

SN - 0022-5142

ER -