Thermal gelation properties of two different composition sardine (Sardina pilchardus) muscles with addition of non-muscle proteins and hydrocolloids

A Thermal Scanning Rigidity Monitor was used to study heat gelation in two sardine minces (S1 and S2) differing in compositional properties (fat content (S1=4.3%, S2=9.6%) and water content (S1=76.5%, S2=72.0%)), protein functionality (soluble protein (S1=62.6%, S2=49.8%) and viscosity (S1=3140 cP, S2=2323 cP)), as well as the contribution to gelation of a number of nonmuscle proteins (egg white, soy protein, sodium caseinate, wheat gluten) and hydrocolloids (iota-carrageenan and starch). The batter of the mince, characterised by higher protein solubility and viscosity and lower fat content (S1), exhibited greater structural stability at temperatures above 50 degrees C. The addition of gelling ingredients always produced an increase in maximum rigidity values, except in the case of sodium caseinate or starch-containing batters of mince with low protein solubility and viscosity (S2), where the rigidity is considerably inferior throughout the experimental temperature range. Of the non-muscle proteins assayed, batters contanining egg white presented the highest rigidity at maximum gelation peak, mainly in the low quality mince (S2). Iota-carrageenan also increased rigidity considerably with respect to the controls. Addition of starch gave less rigidity than iota-carrageenan, although it helped stabilise the formed gel at high temperatures (80 degrees C). Copyright (C) 1996 Elsevier Science Ltd.