Effect of extrusion temperature and pre-extrusion particle size on starch digestion kinetics in barley and sorghum grain extrudates

Particle size heterogeneity in milled barley and sorghum grains: Effects on physico-chemical properties and starch digestibility

“…Similar effects of particle size, after segregation by size, on viscosity have been reported in maize (Onwulata and Konstance, 2006). Particle size after segregation of milled grains has also been shown to have a major effect on response to hydrothermal treatments such as extrusion (Al-Rabadi et al, 2011a) and subsequent starch digestion by amylase after extrusion (Al-Rabadi et al, 2011b). In addition to particle size as previously discussed, differences in the amount of starch (Table 2) are expected to affect at least the quantitative value of viscosity parameters.…”

“…However, this is often done with a low level of water addition and at a relatively low temperatures (such as cold pelleting treatment), resulting in only partial starch gelatinisation (1e20% of the starch present) (Svihus et al, 2005). Since large particles absorb proportionately less water than small particles, the starch they contain will gelatinise to a lesser extent (Al-Rabadi et al, 2011b), and there will be an increase in their digestibility compared to small grain fragments. Thus the larger grain fractions with the lowest digestibility are least likely to benefit from typical animal feed processing methods, but most likely to maintain desirable slow digestion properties in processed human food.…”

Densely packed matrices as rate determining features in starch hydrolysis

“…Individual particles e.g. granular starches or processed starches vary in their response to enzymatic susceptibility (Al-Rabadi, Torley, Williams, Bryden, & Gidley, 2011;Dhital, Shrestha, & Gidley, 2010), and what behaves as resistant starch in one person may not behave the same way in another (Englyst, Kingman, Hudson, & Cummings, 1996), presumably because of differences in enzyme secretion levels, passage rates etc. For a given starch sample, only the mean value of digestion rate/extent for whole populations of particles can be measured under defined experimental conditions and enzyme concentration.…”

Brief history and future of animal simulation models for science and application

“…However, some aspects of these mechanisms have been undertaken in models of human metabolic control and should now be attempted in animal systems (Dalla Man et al 2007;Farhy 2010;Chambers et al 2013). Furthermore, recent research shows that the rate of digestion of grains and pulses in the small intestine of pigs is closely related to the diffusion rates of amylolytic and protease enzymes into the feed particles (Al-Rabadi et al 2009, 2011a, 2011bMahasukhonthachat et al 2010aMahasukhonthachat et al , 2010bDhital et al 2010;Tinus et al 2012). The rate of enzyme diffusion appears to be influenced by several factors including particle size, physical and chemical characteristics of the grain such as degree of compaction, hardness, endosperm cell-wall integrity, gelatinisation, retrogradation of starch and surface hardening of pellets.…”