RESUMO
This research investigated the improvement in the texture of chicken and beef sausages induced by using microbial transglutaminase (MTG). The ε-(γ-glutamyl)lysine (G-L) content and the extractability of myofibrillar proteins from these sausages were also investigated. Treatment with MTG significantly affected the breaking strength score in both meat types, especially for beef cooked at 80°C (p<0.001). The protein concentration of both meat types treated with MTG and extracted in water-soluble protein solution (WSP) was slightly decreased; compared with a significant decrease (p<0.003) in samples extracted in Guba-Straub-ATP solution (GS-ATP). The variation in protein extractability of both meat types could lead to some considerations of the mechanisms and the high affinity reaction between MTG and myosin heavy chain (MHC). SDS-PAGE analysis revealed significant changes in the density of the bands after adding MTG, especially for the beef samples. The G-L content in the presence of MTG was double that in control samples of both meat types. The amount of crosslinking in chicken and beef meat was different and found to be reasonable. Collectively, this suggests that the binding ability of myofibrillar proteins with MTG is strong and dominated by MHC. There was a unique reaction among MHC proteins with MTG molecules considered as a very advantageous reaction. This leads us to suggest that the functional properties of MTG make it a beneficial protein-binding agent, positively helping the functionality of proteins to improve the texture and gelation of meat products that are treated mechanically, such as sausages. Some variation in gel improvement level between chicken and beef sausages was observed; this resulted from the variation in meat proteins in response to MTG, as well as to the original glutamyl and lysine contents.