In vitro evaluation of the effects of steam-flaking conditions on starch availability of barley grain

Abstract

ABSTRACT Objective The objective was to determine how steam-flaking conditions affect starch availability of barley grain. Materials and Methods Five independent sources of barley were used in a 3 × 3 + 1 factorial with the main effects of steam-conditioning duration (5, 20, or 35 min) and flaking density [targeting 0.43 (HFD), 0.34 (MFD), and 0.25 (LFD) kg/L] compared with samples that were not processed (control). Samples were analyzed for 7-h in vitro digestibility, amyloglucosidase reactive soluble starch (AGR), and 6-h amylase reactive insoluble starch (ARIS). Insoluble reactive starch, digestive insoluble starch, and predicted ruminal starch digestion (PRSD) were calculated. Results and Discussion Flaking densities were 0.47 ± 0.031 kg/L (HFD), 0.37 ± 0.021 kg/L (MFD), and 0.32 ± 0.010 kg/L (LFD). The control barley had less AGR, ARIS, insoluble reactive starch, and PRSD (P Implications and Applications Relative to the nonprocessed barley grain, steam-conditioning increased starch reactivity, but steam-conditioning durations greater than 5 min had minimal additive effects. Decreasing the flaking density of barley grain increased starch reactivity.