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Effects of Novel Infrared Heat Treatments and Tempering on Rice Pasting Properties

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  2021 ASABE Annual International Virtual Meeting  2100800.(doi:10.13031/aim.202100800)
Authors:   Abass A Oduola, Griffiths G Atungulu
Keywords:   Infrared, Intensities, Pasting properties, Rice, Tempering, Wavelength.

Abstract. Infrared (IR) heating technique has been identified to be advantageous in rapid drying and preserving rice quality. The objectives of this study were to investigate (i) the effect of using selected IR wavelengths treatment on the pasting properties of rice and, (ii) the effects of a tempering step, added to selected IR wavelength treatment, on the pasting properties of rice. Long-grain rough rice (XL 745) with initial moisture content (MC) of 18.4% wet basis (w.b.) was used for this experiment. The samples were treated using nine IR intensities (ranging from 15.71 to 0.73 kW/m2), three product-to-emitter distances (110, 275, and 440 mm), and three heating durations (10, 20, and 30 s). After the IR heat treatment, the samples were tempered in an incubator set at 60oC for 4 hours. The treated samples were conditioned to 12.5% MC (w.b.), milled, and ground. The pasting properties of the rice flour were determined. Rice treated with an IR intensity of 15.71 kW/m2 for 30 s resulted in a significant reduction of peak viscosity from 2511.67 to 1997.33 centipoise (cP). The final viscosity of rice treated at IR intensity of 15.71 kW/m2 for 30 s was reduced from 2902 to 2592.5 cP. After adding the tempering step into the process, the peak viscosity of rice treated using IR intensity of 15.71 kW/m2 for 30 s was reduced from 2511.67 to 1503 cP. Incorporating a tempering step into the treatment process resulted in higher reductions in peak, final, breakdown, and trough viscosities of the sample.

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