Kinetics of color changes of popped rice during microwave popping: Effect of salt and moisture content

Abstract

Paddy, coated with a dielectric salt was popped using microwave energy. The kinetics of color changes of the popped rice with the variation of heating time (0–60 s), sample moisture content (12–18% wb), and level of salt coating (0–5% w/w) were studied. The parameters, estimating the change in color of the popped rice, were measured in terms of L*, a*, b* color coordinate system using a Chroma‐meter. The total color change (ΔE*), chroma (C*), hue angle (H*), and browning index (BI*) were estimated from these measured parameters. The shift in color change with microwave popped paddy was found darker side with the increase in heating time and salt content. These color changes showed that, ΔE* was fitted well to zero‐order kinetic model, while BI* followed a first‐order kinetic model. All these color parameters were fitted to a quadratic equation as a function of salt and moisture content. Both ΔE* and BI* increased with the increase in salt:moisture ratio. Practical applications The color development in the product during microwave popping of paddy is an important sensory quality attribute concerning consumer acceptability. The popping characteristics of paddy and simultaneously kinetics of its color changes are closely associated with the factors like moisture content, level of salt (dielectric) coating and heating time adopted in domestic MW oven. Modeling of the kinetics of color changes could be a useful practical tool in predicting the final and acceptable color of the product. Estimation of heating time for desirable color development of the product could be arrived with certain ratio of salt to moisture contents of the paddy.

Optimization of preconditioning process of pressure parboiled brown rice (unpolished) for microwave puffing and its comparison with hot sand bed puffing

“…In the case of sand‐bed puffing, salt content beyond 4% level showed insignificant effect ( p > .05; vide Figure b). Similar finding was also observed by Devi and Das () in microwave popping of paddy at different levels of salt coating. Effect of preconditioning temperature on the WI was insignificant ( p > .05) for microwave puffed brown rice, while this was found to be highly significant ( p < .001) with positive linear term and negative quadratic ( p < .05) terms for sand bed puffing.…”

“…Salt improves thermal conductivity and dielectric loss factor of rice kernel. The former helps puffing using sand-bed and the latter helps in puffing using microwave energy (Devi & Das, 2017;Arnaud, 1963;Hoke et al, 2005;van der Sman & Bows, 2017). Additionally, preconditioning process makes the kernel surface hard and compact with starch-salt interaction (Das et al, 2015;Mohapatra, 2010).…”

“…Puffing of rice and popping of paddy using microwave energy have been reported by several workers (Devi & Das, 2017;Maisont & Narkrugsa, 2009;Mohapatra & Das, 2011;Swarnakar et al, 2014).…”

Characteristics and process optimization of rice snack (khao‐tan) puffing by home microwave oven

“…The coefficient of the linear term of each factor indicated that yellowness increased when the IMC decreased and when MWP and PT increased, as shown in Figure . When the IMC increased, the yellowness value decreased (Devi & Das, ). The experiment was also showed that increasing the heating time might increase brownness in popped rice.…”

Kinetic Analysis of the Color of Larch Sapwood and Heartwood during Heat Treatment

“…Kinetics studies are generally used to study the color changes in fruits and vegetables, such as chestnuts [21], grapes [22], and rice [23]. The zero-or first-order reaction is suitable for most kinetic analyses, which are mostly applied in the food industry [24].…”