Heat-induced gelation properties of chicken breast muscle salt soluble proteins when mixed with β-lactoglobulin or an α-lactalbumin enriched protein fraction

The heat-induced gelation properties of mixed protein systems containing chicken breast muscle salt-soluble proteins (SSP) and β-lactoglobulin (β-Ig) or SSP and an α-lactalbumin-enriched fraction (α-Ia) in 0-6 M NaCl, pH 6-5, were investigated using dynamic rheology. At 70°C, SSP had greater storage modulus (G') values than mixtures containing SSP/α-Ig. However, at 90°C, mixtures containing 80:20 and 60:40 SSP: β-Ig had higher G' values than SSP alone, indicating that denaturation of β-Ig directly or indirectly facilitates the formation of a more rigid gel structure. On subsequent cooling to 20°C, the extent of structure formation, as reflected by G' values, was greater for SSP than for mixtures containing SSP/β-Ig, which suggests that the denatured β-Ig is unable to interact with the SSP during cooling. Mixtures containing SSP and an α-la-enriched fraction had lower G' values than SSP at 90°C and on subsequent cooling to 20°C, which reflects the poor gelling properties of α-la. A fibrous network was observed when the microstructure of the SSP and 40:60 SSP: α-Ia gels were examined using scanning electron microscopy, while aggregated networks were seen in the β-Ig and 40:60 SSP: β-Ig gels. No significant differences ( p > 0.05) were observed between the water holding capacity (WHC) of SSP and SSP/β-Ig gels. Gels formed from a mixture of SSP and the α-la-enriched fraction had lower WHC than the SSP gels. The myosin heavy chain was a major contributor to gel structure formation in all mixed gel systems.