EXTRUSION STUDIES ON TRITICALE AND IMPLICATIONS FOR STARCH DIGESTIBILITY

摘要

Triticale, a man-made cereal grain of wheat-rye crosses, is mainly used for feed, but its potential for specialty foods is high (Wu et al., 1978; Onwulata et al, 2000; Marciniak et al., 2008). Triticale can substitute up to 70% of wheat in bread, andthere was no effect on growth performance in pigs when triticale replaced barley and maize (Farrell et al., 1983; Tohver et al., 2005). However, although the lysine content of triticale is superior to wheat (Lupano and Anon, 1985), triticale products have been evaluated to be darker, tougher and harder than wheat products (Lorenz, 1974; Khan and Rashid, 1988; Onwulata et al., 2000). and replacing more than 67% of wheat with triticale reduced growth performance in grower pigs (Farrell et al, 1983). The deleterious effects of triticale are thought to be due iu antinutritional factors (e.g. tannins and trypsin inhibitors), but these are variety specific. Heat processing reduces antinutrients, and the heat, shear and pressure effects of extrusion are effective in this regard (Sun et al., 2006; Tran et al., 2008). Moreover, extrusion gelatinises starch and influences starch digestibility to extents dependent on process conditions. Although reports exist (Lorenz et al., 1974; Marciniak et al., 2008; Onwulata et al., 2000: Singh et al., 2001; Wu et al., 1978) on extrusion of triticale, information is limited on triticale starch digestibility and its relationship to the physical properties of triticale extrudates. This study investigated how extrusion influenced colour, specific volume and starch digestibility of triticale extrudates.