43-8 |
Effects of varying pH in porcine myofibrillar protein on rheological and water holding properties |
A. D. WESTPHALEN, Agricultural Engineeering, Iowa State University, Ames, IA 50011, J. L. Briggs, Thermo Electron Corp., 5225 Verona Rd., Madison, WI 53711-4495, and S. M. Lonergan, Iowa State Univ., 2372 Kildee Hall, Ames, IA 50011. Texture of meat products is dependent on the gelation characteristics of myofibrillar protein. Gaining an understanding of the gelation properties 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 (6.0, 6.5, and 7.0) on heat-induced gelation properties of myofibrillar proteins from porcine semimembranosus muscle. Dynamic rheological measurements were taken during heating where the temperature increased by 1°C/ min from 20 - 85°C, following a holding phase at 85°C for 5 minutes to ensure complete gelation and during subsequent cooling where the temperature dropped from 85 - 5°C at a rate of 5°C/min. The changes in the storage modulus (G’) during the heating phase indicated that protein denaturation surpassed the gel formation once the denaturation temperature was reached (51°C) until the temperature reached 60°C, which was indicated as a dip in the storage modulus as a function of temperature. This dip in the curve was more pronounced as pH was increased, indicating a greater rate of denaturation with increased pH. The final storage modulus after cooling was similar regardless of the pH. Water-holding capacity of the cooked gel was determined to have an inverse relationship with the storage modulus of the cooked protein. Results of the current study indicate that protein denaturation and gel formation are pH dependent. Furthermore, rate of gel formation may influence water holding capacity.
Session 43, Food Engineering: Rheology and texture
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