Dynamic rheological behavior of meat proteins during acid‐induced gelation

Abstract

Glucono‐δ‐lactone (gdl) is used to promoting gelification of muscle proteins in restructured foods. Protein gelification can be achieved by lowering enough the pH to promote interactions between protein molecules. The gdl was added to a muscle extract (1.2 % w/w) at 4, 12, 20 and 28°C and pH and rheological behavior were observed using a controlled stress rheometer. Changes in pH induced by gdl hydrolysis were more noticeable at 28°C (final pH 4.40) than at 4°C (final pH 5.02). The gdl hydrolysis rate depends on temperature, being lower at low temperature and increasing with temperature. This temperature influence on pH decrease was reflected on muscle protein gels viscoelastic behavior, where the proteins cross‐linking were caused by the acidification, enough to form a gel structure. Maximum storage (G') and loss (G”) modules were achieved at pH values between 4.5‐5.5, near to myofibrillar proteins isoelectric point. Samples presented a liquid‐like behavior (G'>G") during the acid‐induced gelation. Stronger gels were formed at high temperatures. At this point, loss of solubility and structure were caused by an excess of acid in the medium.