Influence of pH on rheological properties of porcine myofibrillar protein during heat induced gelation

Texture of meaat products is dependent on the gelation characteristics of myofibrillar protein. Gaining an understanding of the gelation mechanism of meat gel systems is beneficial for the development of processed meat products as well as maintaining quality in meat products. The aim of this study was to investigate the impact of pH (5.6, 6.0, 6.5, and 7.0) on heat-induced gelation properties of myofibrillar proteins from porcine semimembranosus muscle. Dynamic rheological measurements were taken as the temperature increased by 1 degrees C/min from 20 to 85 degrees C, followed by a holding phase at 85 degrees C for 3 min to ensure complete gelation and during a subsequent cooling where the temperature dropped from 85 to 5 degrees C at a rate of 5 degrees C/min. Storage modulus (G') increased as gel formation occurred, but decreased after reaching the temperature of myosin denaturation (52 degrees C) until approximately 60 degrees C when the gel strength increased again. This resulted in a peak and subsequent depression in the data. This depression in the curve was more pronounced with increasing pH. Results indicate protein denaturation and gel formation are pH dependent. Furthermore, rate of gelation appears to influence water-holding capacity. (c) 2005 Elsevier Ltd. All rights reserved.