Effects of Microwave, Infrared and Laser Beams on Physicochemical and Functional Characteristics of Cornstarch

Background and Objectives: Modifying characteristics of starch to change or improve its quality characteristics was carried out using various methods including irradiation with electromagnetic waves in the present study.Materials & Methods: Aiming use of a safe method to modify the functional characteristics of starch, effects of microwave, infrared and laser beams on characteristics of cornstarch were investigated for 15 and 30 min at 60 C.Water and oil absorption, transparency, swelling solubility, carbonyl and carboxyl contents, thermal characteristics and rheology of the treated samples were investigated as well. Results:The waves included significant effects on changes in the quality characteristics of the cornstarch, especially their functional characteristics.Using waves and increasing its duration by changing the structure of starch and intermolecular bonds increased solubility and water and oil absorption powers and decreased transparency.The highest solubility and absorptions of water and oil were observed in treated starch with microwave for 30 min and the highest swelling power was observed in starch treated with laser for 15 min.Using waves with increased oxidation caused increases in carbonyl and carboxyl contents with various intensities in the treated starches.Starting temperature of the gelatinization of the treated samples increased and temperature of the end of the gelatinization decreased and therefore melting temperature of the crystals and the necessary energy in the treated samples were estimated lower, compared to the control.Starch suspension showed shear thinning behaviors and consistency coefficient and flow index of the control sample were higher and lower than those of the treated samples, respectively. Conclusion:Selection of the appropriate treatment conditions varies depending on the desired characteristics of starch.The treated starch for 30 min with microwaves was reported superior to other samples for the most functional characteristics.