Thermal gelation properties of myofibrillar protein and gelatin combinations

Partially purified myofibrillar protein was prepared from post-rigor beef muscle tissue. Gelation properties of myofibrillar protein (6-12%), commercial gelatin (1-12%) and combinations of gelatin and myofibrillar (8-12% protein) were compared. Gels were prepared by combining protein, buffer and 2% NaCl with appropriate volumes of water and heating to 70C at 1.4C/min. Samples were cooled to 4C and gel characteristics were evaluated using texture profile analyses. Gel strength increased as protein concentration increased in pure myofibrillar or pure gelatin gels. However, gelatin plus myofibrillar combinations were weaker than gels consisting of either protein alone at similar protein concentrations. The negative impact on gel strength of myofibrillar-gelatin combinations suggests that the two proteins gel by different and apparently incompatible mechanisms producing an overall gelweakening effect. These results indicate that adding gelatin can be detrimental to gel characteristics of muscle food products.