Effects of lactoperoxidase on gelation properties of yogurt

The gelation pH of yogurt was determined using the hot wire method and comp ared with that measured with a dynamic oscillatory rheometer. The Delta the ta w of the hot wire probes began to increase when the increase of the stor age modulus (G') was observed with the dynamic oscillatory rheometer. This result indicated the hot wire method was effective for determining the gela tion pH of yogurt. By using this method, the effects of incubation temperat ure and addition of lactoperoxidase on the gelation pH of yogurt were studi ed. Higher incubation temperature or higher concentration of lactoperoxidas e increased the gelation pH of yogurt. The hydrophobicity of milk proteins was increased by addition of hypothiocyanite (OSCN-), formed by LP system. The increase in gelation pH of yogurt by lactoperoxidase was thought to be caused by the increase in protein hydrophobicity. (C) 1998 Canadian Institu te of Food Science and Technology. Published by Elsevier Science Ltd. All r ights reserved.