Effect Of High Pressure And Dietary Fiber On Gel Qualities Of Blend Surimi Gels

In this thesis, the effects of high pressure, soybean dietary fiber and polydextrose on gel properties of blend surimi gels were investigated. Changes of gel properties of different gels during frozen storage, with dietary fiber or not, induced by high pressure or heating, were also investigated. It was also studied that the cryoprotective effect of polydextrose on myofibrillar protein and surimi gels.The gel properties of gels induced by different high pressures were a little different between ribbon fish and silver carp. Compared with heat treatment, high pressure could improved significantly the gel strength, TPA and the water binding capacity of surimi gels of ribbon fish. However, the hardness and chewiness of silver carp surimi gels induced by high pressure were significantly lower than that induced by heat. But the high pressure of 400 MPa could improve the springiness, cohesiveness and water binding capacity of silver carp gels. The blend surimi gels at the ratio of 1:2 (ribbon fish: silver carp) had better gel properties than that of ribbon fish or silver carp alone, at the treatments of heat or high pressure of not less than 300 MPa.The gels with soybean dietary fiber showed a significant increase in gel strength, hardness, chewiness and decrease in expressible water and cooking loss. But with the addition of soybean dietary fiber up to 8%, the springiness of gels decreased significantly, and yellowness increased. However, the gels induced by high pressure had higher deformation, TPA and lower expressible water and yellowness.The addition of polydextrose below 4% did not have an obvious effect on gel strength, TPA and expressible water of gels induced by heat, but the addition of 8% which made the hardness of gels decrease and the expressible water and cooking loss increase significantly. Although 8% polydextrose also made the gel strength and TPA of gels induced by high pressure decrease, it was still obviously higher than that of gels induced by heat. Furthermore, the addition of polydextrose ranging from 1% to 4% could significantly improve the gel properties of gels induced by high pressure.The optimized most suitable technology of process was high pressure 400 MPa, soybean dietary fiber 4% and polydextrose 4%.There were no significant differences on the gel properties of gels with dietary fiber and induced by high pressure during frozen storage. After seven weeks, the gels still had good gel strength, water binding capacity and sensory qualities. But the gels, without dietary fiber and treated by heat, became a little wore after seven weeks and its water binding capacity decreased to 89.98%.4% polydextrose had a similar cryoprotective effect to 8% sucrose and sorbitol mixture on the myofibrillar protein and surimi gels. During frozen storage, polydextrose could hinder or mitigate the decrease of salt extractable protein content, Ca2+-ATPase activity, G′and sulphydryl content of myofibrillar protein and the gel strength of surimi gels.