Decolorized porcine globin gels produced by heat-induced gelation. Physical and rheological characterization

Abstract

Decolorized porcine globin gels have been developed due to their many potential applications in the area of food technology. In this study they are presented as possible foodstuffs, thickeners or films to cover food products. A precipitating agent and a bleaching agent were used to obtain decolorized globin from hemoglobin. To characterize these films, it was necessary to study their rheology and their resistance to external temperature. Rheological measurements were taken to characterize the gels in combination with the analysis of their microstructure, particle size, thermal behavior and water holding capacity. Results showed that G′ (the elastic modulus) was higher than G″ (the viscous modulus) and that the gelation point decreased with increasing pH for all the samples. Decolorized globin gels behaved dilatantly and presented a viscoelastic response, which was very suitable to form films to cover foodstuffs. DSC analysis corroborated the results obtained from rheological determinations and size distribution measurements presented unimodal curves for all the films. At basic pH, the globin gels were composed of tiny protein aggregates, forming a compact network without spaces between the particles in gels produced at pH 2. Gels produced at neutral pH were composed of a few large protein aggregates embedded in a matrix of smaller diameter particles. Furthermore, these gels presented an elevated moisture content and a very high WHC, which are desirable properties due to their potential applications.