No 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.

Microwave popping characteristics of a particular variety of paddy were studied using a domestic microwave oven. The experiments were carried out at 4 levels of moisture content (around 13%, 14%, 15% and 16% wb), 3 levels of power (600 W, 850 W and 1000 W) and 5 levels of heating time (40 s, 60 s, 80 s, 100 s and 120 s). A general factorial experiment design was followed, and effect of different treatment combinations on popping percentage and expansion ratio of the paddy was evaluated. The maximum popping percentage of 63.47% was obtained at a moisture content of 14.15% and energy level of 80 kJ (1000 W and 80 s) while the maximum expansion ratio of 4.42 was obtained at 14.94% moisture content and energy level of 68 kJ (850 W and 80 s). Optimum values of microwave power, time of heating and moisture content of paddy were achieved at 1000 W, 80 s and 15%, respectively, corresponding to popping percentage and expansion ratio of 58.73 and 3.58.

The objective of this study is to discuss the inhibitive behaviour of two inorganic corrosion inhibitors namely sodium nitrite, an anodic inhibitor and zinc oxide, a cathodic inhibitor on steel embedded in concrete containing quarry dust as fine aggregate. Each inhibitor was evaluated for various strength properties such as compressive strength, split tensile strength, flexural strength and bond strength in addition to water absorption capacity. The performance of the inhibitors on corrosion resistance was studied using impressed voltage method, rapid chloride ion penetration test, AC impedance measurement and weight loss measurement. The surface analysis of the embedded steel was carried out by scanning electron microscope analysis. Based on the results of strength and durability tests the optimum percentage of inhibitors to be added in quarry dust concrete was determined. The experimental results demonstrate that addition of inhibitors enhances the corrosion resistance properties and does not have any adverse effects on strength properties.