Fabrication of Laboratory Scale Ohmic Heater and Its Application in Wheat Bran Stabilization

Abstract

A laboratory scale ohmic heater was developed and assessed its performance on stabilization of raw wheat bran. Electrical conductivity (EC) of wheat bran samples was measured at three moisture content (w.b.) 40, 50 and 60%, respectively, by applying voltage gradients from 35 to 50 V/cm. The EC increased significantly with increase in temperature and moisture content. From the temperature range of 25–90C, the range of EC values (siemens per meter) for wheat bran were observed from 0.04 to 0.12, 0.05 to 0.20 and 0.15 to 0.50 S/m at 40, 50 and 60% moisture content (w.b.), respectively. The treated (ohmically heated) and control (raw) wheat bran sample was stored under accelerated storage conditions. The free fatty acid (FFA) concentration of the treated samples showed a very slow growth in comparison to the control for storage period of 90 days. It was observed that ohmic heating is a significant method for effective stabilization of wheat bran. Practical Applications Wheat bran is easily available and a by-product in wheat milling industry. Wheat bran contains good amount of fibers, protein, minerals and fat but its applications are limited due to formation of free fatty acid. Due to their high levels of polyunsaturated fatty acids and enzymes, wheat germs are susceptible to deterioration. Therefore, they are stabilized and dried in a gentle heat treatment process. The following are the benefits of stabilization: (a) no partial deoiling, (b) increase in vitamin E content, (c) high nutritional value and density, (d) delicious taste: nutty and crisp and (e) pure wheat product. In this study, ohmic heating was performed rather than conventional methods to stabilize the wheat bran. The application of ohmic heating on wheat bran will provide solutions to the food industries as it has various applications in food, fermentation, feed and medicine industries.