Control of viscosity in starch and polysaccharide solutions with ultrasound after gelatinization

Ultrasound irradiation in the production of ethanol from biomass

“…According to Iida et al [82], the molecular weight of waxy maize starch sharply decreased in the initial period of 10-30 min sonication and thereafter the depolymerization continued slowly. Also, the starch molecule chains regularly decrease with increasing ultrasound intensity and progressively approach the minimum chain length [83].…”

“…The degree of granule disintegration increases as the swelling of the starch granules treated by heat proceeds as the temperature increases (Table 7). With the ultrasonic treatment as short as 1 min, the swelled granule disintegrates and a certain amount of the contents is solubilized [82]. With increasing ultrasound power and intensity, the swelling power increases.…”

“…The shear stress created by stable cavitation is considered effective if able to degrade high molecular weight polymers even without the presence of bubble collapse [101]. Ultrasonic treatment apparently expedites the polymer degradation of starch by separating the amylopectin chains and leaching out amylose chains from the collective entity [82]. The shear forces introduced by ultrasound waves can weaken the interactions between the polymer-molecules and as a result, the viscosity is reduced by the destruction of the polymer network [82].…”

“…Ultrasound irradiation can cause the physical degradation of starch granules, reduction in starch suspension viscosity as well as a decrease in molecular sizes of starch polymer [85b,90b,107]. A drastic decrease was observed in viscosity of the solutions with 5% and 10% of waxy maize, potato, tapioca, sweet potato, glucomannan (1%) and pectin that were sonicated for 30 min after gelatinization (Table 8) [82]. This viscosity reduction in the sonicated starch solutions was also observed even by cooling to room temperature.…”

“…This trend might be attributed to the fact that mechanical effects of ultrasound effectively develop in relatively low viscosity conditions, which are associated with higher temperature [82]. Because the cavitation effects at lower temperatures are more effective than the mechanical effects at higher temperature on the viscosity depression of starch solutions, the decrease in viscosity due to rising sonication temperatures is not so remarkable.…”