Rheology and microstructure characterisation of small intestinal digesta from pigs fed a red meat-containing Western-style diet

• Methodology for porcine small intestinal digesta characterisation developed.
• Systematic changes observed in digesta microstructure during small intestinal transit.
• Rheological properties reflect balance between digesta hydrolysis & net water uptake.
• Large variations in modulus & viscosity values for genetically-similar animals fed same diet.

A method to characterise rheological and microstructure features of whole digesta collected from pigs fed meat-containing western style diets is described. Digesta are shown to contain suspensions of meat fibre particles up to 300 μm in size which exhibit weak gel behaviour, have a dynamic viscosity higher than steady shear viscosity indicative of structural breakdown at the initiation of flow, and shear thinning behaviour under steady shear. The power law index approach is useful for capturing the overall features of rheological behaviour under both small (n*<0.3) and large deformation (typically 0.2 < n < 0.5) conditions. Values obtained for rheological parameters represent a balance between the digestion of structural components (meat particles and starch granules in this case) with the absorption of water along the small intestine, and result in the absence of any systematic pattern as a function of small intestinal site. Both primary rheological data (G′, G″, η, η*) and power law index parameters show a high level of variability between animals fed identical diets. This study provides a baseline from which to investigate the in vivo effects of hydrocolloids on the rheology of porcine digesta from diets representative of human meals.

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