Effect of heat-moisture treatment on rice starch of varying amylose content

Abstract

a b s t r a c tThe effect of heat-moisture treatment (HMT) on the properties of rice starches with high-, medium-and low-amylose content was investigated. The starches were adjusted to 15%, 20% and 25% moisture levels, and heated at 110°C for 1 h. The swelling power, solubility, pasting properties, morphology, enzymatic susceptibility and X-ray crystallinity of the starches were evaluated. HMT reduced the swelling power and solubility of the starches. The strongest effect of HMT occurred on the high-amylose starch; the pasting temperature was increased and the peak viscosity, breakdown, final viscosity and the setback were reduced. HMT increased the starch's susceptibility to a-amylase and promoted a reduction in the starch relative crystallinity.

Effect of Heat Moisture Treatment Using Different Solvents and Incubation Times on Resistant Starch Formation of Rice Flour

“…These results were consistent with other studies (Gunaratne and Hoover, 2002;Watcharatewinkula et al, 2009). In addition to the rearrangement of amylose and amylopectin inside the starch granules, as suggested by many researchers (Hoover and Vasanthan, 1994;Khunae et al, 2007;Zavareze et al, 2010), the interactions of starch granules and other flour components during the heat moisture treatment also strengthens the structure of the flours, as denoted by greater differences in enthalpy change before and after the heat moisture treatment of the flour samples. The full and partial gelatinization of starch granules could also be a reason for the markedly reduced viscosity of heat moisture treated flour.…”

Emulsifiers and thickeners on extrusion-cooked instant rice product

“…α-Amylase Susceptibility (AS) was measured following the modified procedure described in previous report (Zavareze et al 2010). Ten grams of sample flour was dispersed in 47 ml phosphate buffer (0.2M, pH 6.0).…”

The impact of heat-moisture treatment on the molecular structure and physicochemical properties of normal and waxy potato starches

“…Regardless of starch origin, HMT reduces granular swelling and anlylose leaching of many starches (Chung et al, 2009;Gunaratne et aI., 2010;Gunaratne and Hoover, 2002;Hoover et aI., 1994;Hoover and Manuel, 1996;Hoover and Vasanthan, 1994a;Hormdok, and Noomhorm, 2007;Olayinka et al, 2008;Sair, 1967;Zavareze et al, 2010). However, in some cereal starches, such as rye, barley, triticale, finger millet and wheat, amylose leaching has been shown to be increased on HMT, inspite of reduced granular swelling (Adebowale et al, 2005a;Kulp and Lorenz, 1981;Kurakake et al, 1996).…”

“…NPand WPstarches exhibited heterogeneity in degradation (NP>WP) Most studies have been on the impact ofHMT on the thermal properties, crystallinity and pasting propertiesofnorrnalstarches. Some researchers (Hoover and Manuel, 1996; Kweon el al., 2000;Zavareze et al, 2010) have attempted to explain the impact of HMT on the structure and physicochemical properties of starches varying in amylose content. However, the part played by amylose during HMT of starches is still not properly understood.…”

“…Furthermore, the impact ofHMT on starch digestibility has received only scant attention. Kweon et al (2000) and Zavareze et al (2010) studied the influence of moisture content during HMT on the digestibility of normal, waxy and high amylose maize (llOoC/16 h) and rice (llOoC/I h) starches, respectively. Digestibility of HMT maize starches by porcine pancreatic a-amylase (PPA) was shown to decrease in the moisture range of(15-21%) but to increase at 27% moisture (Kweon et al• 2000).…”