Effects Of Okara On The Gel Properties And Freeze-thaw Stability Of Silver Carp Surimi

Surimi products become increasingly popular as a high-grade aquatic processing product, they have high protein, low fat and are easy to digest, meanwhile, raw material is rich and not restricted by the size of the fish, in the processing also can be allocated reasonably according to the actual need, producing different flavor and specific functional products. Okara is the fibrous residue of soy food industry, and is rich in protein and dietary fiber, a certain amount of okara added into surimi products may enhance and improve the product’s flavor and taste. The aim of this study is to research the effects of okara’s addition levels, particle size and fat content on the silver carp surimi gel and its freeze-thaw stability.Firstly, the effect of okara addition levels on water holding capacity (WHC), texture, sensory, color and dynamic rheological property of surimi was studied. As okara concentration increased, WHC, texture, breaking force, gel strength and whiteness of surimi gels were significant decreased (P<0.05), but there was no difference (P>0.05) on WHC and gel strength when okara concentration above6%. Sensory scores decreased with okara concentration, all the sensory project grades were above4when okara addition amount was less than6%. Dynamic rheological test revealed that storage modulus and loss modulus decreased along with increasing okara concentration.Then, the effect of okara particle size on WHC, texture, sensory, color and dynamic rheological property of surimi was studied when okara adding amount remained unchanged. As okara particle size decreased, hardness, gumminess, chewiness, breaking force and gel strength were significant decreased (P<0.05), but there was no difference (P>0.05) on gel strength when okara particle size was less than387μm. Springiness, cohesiveness and whiteness of surimi gels increased gradually. All the sensory project grades except elasticity showed no significant change (P>0.05). Dynamic rheological test revealed storage modulus and loss modulus increased along with okara particle size decreasing. The study investigated the effect of okara oil content on WHC, texture, color and dynamic rheological property of surimi. As okara oil content decreased, WHC, texture, breaking force and gel strength of surimi gels increased slowly. Deoiling treatment increased L*value and whiteness of surimi gels. Dynamic rheological test revealed okara oil decreasing slowed storage modulus and loss modulus reduction.At last, the effects of okara on WHC, texture and color were studied during the freeze-thaw process. WHC, texture, breaking force, gel strength and whiteness of surimi gels were significant decreased (P<0.05). Deoiling treatment of okara increased WHC, texture, breaking force, gel strength and whiteness of surimi gels reduction comparing with okara if only focused on every freeze-thaw process. Thus okara seemed to be slow down quality changes caused by freezed and thawed.Results of the study provide a certain theoretical basis to add okara to produce more nutritious and healthy surimi products, meanwhile, analyses the effects of different okara composition on surimi gel and had an important reference to further academic research.