Abstract:
Wheat Gluten Protein (WGP) prepared by gluten through hydration build a great and compact network structure, which has great viscoelasticity, extensibility and film formability. However, the structure is easy to break after heating due to low stability and water-holding capacity. In this research, a blended system was established to contain the vegetable protein, hydrophilic colloid, and coagulating gelatinase using the wheat gluten, Soy Isolated Protein (SPI), Methylcellulose (MC), and Glutamine Transaminase (TG). It is vital to investigate the effects and relationship between above components of the physicochemical properties, gel properties and structure in the blended adhesion system. The results showed that the SPI, MC and TG were added step by step to WGP and the disulfide bond content in the mixed system decreased by 81.03%, increased by 248.50% and 0.70%, the free sulfhydryl group content increased by 68.79%, 28.90% and 20.44%. Meanwhile, the surface hydrophobicity increased by 5.07%, decreased by 6.85%, and increased by 17.17%, decreased by molecule weight of glutenin component increased gradually with the gradual addition of WGP into the mixed system. The water holding capacity increased by 5.25%, 2.91%, and 2.79%, and the gel strength increased by 104.14%, 24.66%, and 3.52%. When it comes to the molecular weight, SPI could perturb the WGP network structure, and the less soluble parts of SPI intersect with WGP leading to the disappearance of some subunits. The MC was added to strengthen the cross-linking between proteins, further producing increasing aggregates for the molecular weight, but the TG enzymes dispersed the large aggregates into the uniform small aggregates. During the progressive addition of the three fractions, the tangles of molecular chains in the gel system increased with the degree of gelation, and the storage modulus and loss modulus rise gradually. The TG enzyme was added to prevent the transforming of α-helix structure into β-turn and irregular coil structure, leading to the increase in the α-helix and β-sheet content. The intermolecular entanglement points of the gel in the blend bonding system promoted stronger gel property. This showed that the addition of SPI partially destructed the network structure of WGP, but the MC and TG enzymes would promote the aggregation degree and strength of protein gel. The gel structure was formed by SPI bind to the WGP covalent, disulfide bonds, and hydrophobic interactions. The MC was added to cause the double protein water loss aggregation through hydrogen bonding. The TG enzyme was further induced to promote the crosslinking between SPI and WGP to make the skeleton network structure closely. The SEM observation indicated that the SPI was embedded in the WGP network skeleton, forming a new architecture as half network and half filling. With the addition of MC and TG enzymes in turn, on the basis of a large number of cross-linked filamentous structures, local continuous membrane structures were formed to cover the particles by Soybean Drawing Protein (SDP). It showed that the SDP particles were completely and tightly wrapped in the gluten SPI-MC-TG enzyme blend adhesive system. The SDP based meatloaf was made using this bonding system, and four raw materials were added to the rehydrated SDP in turn, which showed that the hardness, cohesion, chewiness, and elasticity of the meatloaf were improved. Therefore, it is an effective way to establish the gluten based blending adhesive system for better quality meat products, particularly with the SDP as the main raw material.