Effect of Conditioning Agents on the Structure of Tempered and Steam‐Flaked Sorghum

Abstract

Cereal Chem. 75(1):58-63Tempering agents affect the pericarp of steamed grain and the endosperm of steam-flaked sorghum. Examination by environmental scanning electron microscopy (ESEM) clearly showed that β−mercaptoethanol (BME), sulfurous acid (SA), phosphoric acid, and cellulase significantly altered the structure of the pericarp and endosperm during tempering. Lime and protease had a lesser effect on the pericarp structure of the kernels, and had little effect on the endosperm. Steamed flakes from the SA treatment were more translucent and durable than all other treatments. Flakes with BME were translucent and high in quality, but were more fragile than the SA flakes. Nontempered, water only, and commercial conditioner treatments produced flakes with the lowest quality. Peak, final, and breakdown Rapid Visco Analyzer (RVA) viscosities were low-est for the SA flakes due to disruption of the starch chains by the weak acid. BME viscosity values were higher than SA, but lower than the water and commercial tempering treatments. The commercial conditioner (15× normal concentration) did not alter kernel structure and did not cause any changes in the RVA profiles over kernels tempered with water alone. Starch gelatinization, measured by enzyme susceptible starch (ESS), was highest in the SA and BME flakes and lowest in the nontempered flakes. Feedlot operators may be able to save money by avoiding the use of chemical additives that do nothing to the grain. By using chemicals proven to have positive effects on flake quality, operators could save money by reducing the processing time and energy needed to produce good quality flakes.

Assessing Fermentation Quality of Grain Sorghum for Fuel Ethanol Production Using Rapid Visco‐Analyzer

“…Compared with wheat and corn, fewer studies have reported on using RVA to study grain sorghum and its associated products. RVA has been used mostly to investigate the pasting properties of isolated sorghum starches or starches in raw, dehulled, decorticated, flaked, and malted sorghum grains, with solid levels of 8.6-14.0% (w/w) in the slurries (Cruzy Celis et al 1996;Moheno-Pérez et al 1997;Taylor et al 1997;McDonough et al 1998;Beta et al 2000Beta et al , 2001Hugo et al 2000;Suhendro et al 2000;Xie and Seib 2000;Beta and Corke 2001a,b;Agu et al 2006). Previous studies reported RVA procedures with temperature profiles of 13, 18, and 22 min.…”

Resistant‐Type Starch in Sorghum Foods—Factors Involved and Health Implications

“…With a steam temperature of 99 °C and a gap between the corrugated flaking rollers of 45 µm, steam flaking of sorghum grain was shown to rupture the starch granules with release of starch to form a continuous phase, especially with preconditioning (tempering) of the grain, in addition to causing swelling and distortion of the gelatinized granules (Figure 1C). [ 75 ] With extrusion cooking, the cereal flour is subjected to multiple effects. [ 76 ] There is wet heating under pressure and mechanical shear stress in the extruder barrel and steam‐driven product expansion at the die.…”

Physical and Milling Characteristics of Wheat Kernels After Enzyme and Acid Treatments

“…Increasing the moisture content of wheat by tempering, usually from 11-12% to 16-18%, toughens (plasticizes) the bran layers and facilitates their removal as large pieces. Water uptake during tempering occurs in two distinct phases: adherence to the surface of the kernel and diffusion into the kernel (McDonough et al 1998). When added to temper water, conditioning agents, such as general surfactants, reduce water surface tension and help water adhere to the kernel surface.…”

“…When added to temper water, conditioning agents, such as general surfactants, reduce water surface tension and help water adhere to the kernel surface. McDonough et al (1998) reported the use of conditioning agents (β-mercaptoethanol and sulfurous acid) in the tempering and flaking of sorghum. These agents disrupted pericarp and endosperm structures in two ways: by removing or disturbing waxy layer outside the pericarp, and by disrupting disulfide bonds in sorghum protein throughout the kernel endosperm (McDonough et al 1998).…”

“…McDonough et al (1998) reported the use of conditioning agents (β-mercaptoethanol and sulfurous acid) in the tempering and flaking of sorghum. These agents disrupted pericarp and endosperm structures in two ways: by removing or disturbing waxy layer outside the pericarp, and by disrupting disulfide bonds in sorghum protein throughout the kernel endosperm (McDonough et al 1998). The seed coat of wheat contains a hydrophobic cutinous layer (MacMasters et al 1978) that can act as a water repellent.…”