关键词: 肌原纤维蛋白, 甘蔗膳食纤维, 凝胶特性, 微观结构, 质构

Abstract:

【Objective】 The relationships between the myofibrillar protein gel networks, the spatial distribution of dietary fiber and protein, and the textural property of composite gel were investigated in present study. The aim of this study was to expound the mechanism of myofibrillar protein gel influenced by modified sugarcane dietary fiber (SDF), so as to provide a theoretical basis for the application of sugarcane dietary fiber as fat replacement in low-fat sausage. 【Method】 The present study modified the physicochemical properties of sugarcane dietary fiber by hydrogen peroxide treatment. The myofibrillar protein with various concentrations and particle sizes of sugarcane dietary fiber were set as the model system. The treatment without SDF was the control; the treatment with 1%, 2% and 3% 50-mesh SDF addition respectively named T150, T250 and T350; the treatment with 1%, 2% and 3% 100-mesh SDF addition respectively named T100, T200 and T300.The dynamic rheological properties were analyzed by the rheometer; the true fracture stress and strain of composite gels were analyzed by the textural instrument; the spatial distribution of sugarcane dietary fiber in the MP gels were observed by the paraffin section, the microstructure and corresponding image analysis of myofibrillar protein gel networks were analyzed by the SEM and the image analysis software. 【Result】 With the increase of concentrations and particle sizes of sugarcane dietary fiber, the centrifugal loss of composite gel significantly reduced, while the storage module (G') significantly increased. The result showed that the SDF addition significantly increased the fracture stress, while the SDF addition significantly reduced the fracture strain. Paraffin section showed that the sugarcane dietary fiber did not directly interact with protein. The dietary fiber just simply trapped in the protein networks and formed numerous various shapes and volumes cavities. The SEM showed that the myofibrillar protein networks under the control were filled with the connected moisture channels, and the existing of the moisture channel seriously hindered the interaction of the hydrophobic groupings, leading to the loose networks. The dietary fiber addition reduced the cross-linked moisture channels, and promoted the formation of compact and well-aggregated MP gel networks. The image analysis results showed that the treatment T350 had the highest fractal dimension value of 1.8670 and the lowest lacunary value of 0.19.【Conclusion】 The composite gel was comprise of the frame structure formed by the heat-induced gel protein networks and the filled structure formed by the SDF as the filling phase and protein matrix as the continuous phase. The physicochemical properties of SDF proved that the water holding capability was correlated with the particle size. Hence, the treatment with 3% 50-mesh sugarcane dietary fiber could promote the aggregation of myofibrillar protein through moisture stability, and had the highest stress. But the 50-mesh SDF was inelastic structure and formed various shapes and volumes cavities in gel networks, which significantly reduced the strain of composite gel. In conclusion, the 100-mesh SDF (smaller particle size) as fat replacement could significantly increase the stress of composite gel, and ultimately maintain the elasticity of the composite gel.

Key words: myofibrillar protein, sugarcane dietary fiber, gelation property, microstructure, textural property