14B-15 |
Use of dielectric properties to determine starch gelatinization |
O. SIPAHIOGLU, Department of Food Sciences, United Arab Emirates University, Al Maqam Campus, Department of Food Sytems, P.O.Box 17555, Al Ain, United Arab Emirates, C. Bircan, Department of Food Science, Adnan Menderes University, Gida Bilimi Bolumu, Ziraat Fakultesi, Aydin, Turkey, and S. A. Barringer, Dept. of Food Science & Technology, Ohio State Univ., 2015 Fyffe Ct., 317 Parker Food Science Bldg., Columbus, OH 43210-1007. Dielectric constant and dielectric loss factor of foods are affected by the amount and the mobility of water. Gelation of proteins and starches affect water mobility. Recent research has shown that it is possible to determine protein denaturation because it is marked by an abrupt change in the dielectric properties in protein solutions and meats. Therefore, it might be possible to determine the gelatinization temperature of starch solutions using the dielectric properties. The objectives were to demonstrate that starch gelatinization can be detected by the dielectric properties, and to determine the influence of this change on the dielectric property values. Dielectric constant and dielectric loss factor of suspensions, pastes and settled solutions of potato starch with varying moisture contents (80-99% w/w) were measured from 20 to 95°C using a network analyzer from 915 to 2450MHz. The dielectric constant of pasted starch samples was higher than the suspended starch solutions at the same moisture content. The settled starch samples were considerably lower than the other two. Dielectric constant decreased or stayed constant with temperature until gelatinization. It abruptly increased at gelatinization for settled starch samples. The lower the amount of starch, the higher the change in dielectric constant. The magnitude of change was lower for suspended starch samples. No change was observed for pasted starch samples. The dielectric loss factor of all samples decreased with temperature. An abrupt change around the gelatinization temperature was observed with suspended and settled starch samples but not with pasted samples. However, the change was more noticeable with the dielectric constant than the dielectric loss factor. Starch gelatinization can be observed through this new method.
Session 14B, Food Chemistry: Physicochemical properties
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