Environment and Hybrid Influences on Rapid-Visco-Analysis Flour Properties of Food-Grade Grain Sorghum
Grain processors would benefi t from informa- tion about the production environment and the infl uences of the sorghum (Sorghum bicolor (L.) Moench) hybrid on food-grade fl our proper- ties. The objective of this study was to deter- mine the effects of environment and hybrid on rapid-visco-analysis (RVA) fl our properties of commercially available food-grade sorghum. A randomized complete block experiment was planted in 12 environments, which included the 2004 and 2005 growing seasons and irrigated and dryland water regimes in eastern, central, and west central Nebraska, and a dryland, low-N environment in eastern Nebraska. The environment accounted for 71-85% of the total variation in RVA parameters, while the hybrid accounted for 11-23% and the environment- by-hybrid interaction, 1-3%. Unfortunately, the results of this experiment suggest that it is dif- fi cult to predict the effect that environment will have on resulting sorghum-fl our parameters. Although of secondary importance in terms of total variation in sorghum-fl our RVA properties, the choice of hybrid predictably and signifi - cantly contributes to sorghum-starch viscosity properties. Food-grade hybrids were grouped based on viscosity properties into those best suited for dry-mill and alkaline-cooked prod- ucts (Asgrow Orbit; Sorghum Partners NK1486) and those best suited for porridge, consumable alcohol, and ethanol production (Kelly Green Seeds KG6902; NC+ Hybrids 7W92; Asgrow Eclipse; and Fontanelle W-1000). These results were consistent with those previously reported for grain density.
Crop Rotation and Soil Amendment Alters Sorghum Grain Quality
Soybean [Glycine max (L.) Merr.] rotation enhances grain sorghum [Sorghum bicolor (L.) Moench] yield, but influence on grain quality has not been measured. The objective was to determine the effect of cropping sequence (CS) and soil amendment (SA) on grain yield and quality. Sorghum grain yield and quality, soil NO 3 -N and water were measured in a rotation study in 2003 and 2004 on a Sharpsburg silty clay loam (fine, smectitic, mesic Typic Argiudoll). Cropping sequences were continuous sorghum, and sorghum rotated with non-nodulating and nodulating soybean. Soil amendments consisted of no amendment, manure (17-26 Mg dry matter ha -1 yr1), and N (84 kg ha-1 yr1). CS x SA interaction effects were found for most parameters. Rotation with non-nodulating soybean without SA increased yield by 2.6 to 2.8 Mg ha-1 over continuous sorghum without SA. Rotation without SA with nodulating soybean further increased yield by 1.7 to 1.8 Mg ha-1 over rotation with non-nodulating soybean. Grain N increased by 0.5 to 1.0, 2.5 to 5.0, and 3.3 to 4.9 g kg-1 for N application to continuous sorghum and sorghum rotated with non-nodulating and nodulating soybean, respectively. Tangential abrasive dehulling device (TADD) removal indicated that continuous sorghum without SA produced the softest grain with 43 to 44% TADD removal, and sorghum rotated with nodulating soybean with manure produced the hardest grain with 22 to 27% TADD removal. As food end-use opportunities for sorghum grain evolve, use of crop rotation and SA application will be important to produce grain with desirable quality attributes.
FACTORS INFLUENCING BETA-AMYLASE ACTIVITY IN SORGHUM MALT
An investigation into factors influencing beta-amylase activity in sorghum malt confirmed that ungerminated sorghum grain exhibited essentially no beta-amylase activity. Malted sorghum had beta-amylase activity less than 25% of the level in barley malt. Neither reducing agents nor papain affected beta-amylase activity in sorghum, indicating that the enzyme is not in a bound form, unlike in barley. Isoelectric focusing indicated that sorghum beta-amylase comprises just one major and one minor isozyme of pl approximately 4.4–4.5, unlike the many isozymes all of higher pl in barley. However, like barley, sorghum beta-amylase was more temperature-labile than its alpha-amylase. Beta-amylase activity in sorghum malt was increased by germination time, high germination moisture and over the germination temperature range investigated (24–32°C), 24°C gave the highest activity. The beta-amylase activity of sorghum malts was significantly correlated with malt diastatic power, despite the fact that alpha-amylase and not beta-amylase is the predominant diastatic enzyme in sorghum malt.