Effect Of Pre-emulsification Of Plant Lipid Treated By Ultrasound On The Functional Properties Of Chicken Breast Meat Myofibrillar Protein Composite Gel And Meat Batter Quality

Low temperature emulsion-type comminuted meat product is one of the most popular meat products,and it is a typical product in emulsion theory,the processing and application of meat science.This kind of products contains the muscle protein,moisture,fat,connective tissue and other ingredients.The emulsification of comminuted meat is a complex system of water-protein-fat in the processing procedure.In addition,fat plays a key role in increasing the taste and flavor of emulsion-type meat product.However,high levels of fat added in the products affect the physical health of consumers.The pre-emulsification method could reduce the amount of fat in emulsified meat products.In order to reduce the fat content,and make the emulsion-type comminuted meat product achieve good emulsification stability at the same time,this study was based on the application for new technology of pulsed ultrasound to improve the emulsification stability of pre-emulsion.This study includes three parts,the contents and results are as follows:1.Effect of ultrasound treatment on the emulsification stability of sodium caseinate-emulsified soybean oil emulsionIn order to improve the emulsifying stability of pre-cmulsified sodium caseinate-soybean oil emulsion,ultrasound was used.Effect of ultrasound time(0,3,6,9 and 12 min)with 20 kHz,450 W on pH value,conductivity,creaming index,droplet mean diameters and size distribution and viscosity of pre-emulsion were performed in this study.There was no significant difference among emulsions treated with different ultrasound time in pH and conductivity(P>0.05).Creaming rate tests showed that ultrasound-treated samples had similar creaming index at 0 h(P>0.05),but smaller than the control at 12 h,24 h and 36 h(P<0.05).With the increasing of ultrasound time,D4 3,D3 2 and D50 of sodium caseinate-emulsified soybean oil emulsion droplet decreased,and the viscosity of emulsion at a shear rate of 0.1 s-1 increased significantly(P<0.05).These findings show that ultrasound treatment of pre-emulsified emulsion stabilized using sodium caseinate could extend the storage period,reduce the particle size of emulsion,increase the viscosity,so as to improve the emulsification stability.2.Effect of pre-emulsification of plant lipid treated by ultrasound on the functional properties of chicken breast myofibrillar protein composite gelTo explore the effect of pre-emulsification of plant lipid treated by ultrasound on the functional properties of myofibrillar protein(MP)gel,pre-emulsified plant lipids prepared using ultrasound were used to replace animal fat incorporating into chicken breast MP.MP-soybean oil emulsion composite gels(SMG)were prepared from 3%chicken breast MP with 27.5%soybean oil incorporated as pre-emulsification with 0.5%sodium caseinate(0.6 mol·L-1 NaCl and 50 mmol·L-1 phosphate solution,pH 6.25).One-factor-at-a-time experiments were carried out to investigate the effect of different ultrasound treatment times on the texture[rheology and texture profile analysis(TPA)],water-and fat-binding(WFB)capacities,and microstructural properties of SMG.Rheological tests showed that ultrasound-treated samples formed a more viscoelastic gel than the control.WFB and textural properties were also significantly improved by pulsed ultrasound(P<0.05).The ultrasound-treated gels exhibited homogeneous fine network microstructures when the ultrasound time was 6 min.G'72? and G''72? were highly correlated(P<0.01)with WFB and TPA(hardness,springiness,chewiness,cohesiveness,and resilience).These findings show that ultrasound treatment has potential in improving the functional properties of myofibrillar protein-soybean oil emulsion composite gels.3.Effect of pre-emulsified emulsion treated with ultrasound on qualities of low-fat frankfurter-style sausagesPre-emulsified sodium caseinate-soybean oil emulsion prepared with pulsed ultrasound was used to replace pork back fat in frankfurter-style sausages.Effect of ultrasound pre-emulsified emulsion with different substitution rate(25%,50%,75%,100%)on the chemical composition,color parameters(L*,a*,b*),textural properties(hardness,chewiness,springiness,cohesiveness,resilience),water-and fat-binding(WFB)capacity(cooking loss,expressing loss),water distribution and microstructure of frankfurters was performed in this study.With the increasing of substitution rate,the moisture of frankfurters became lager,fat content and energy value became smaller(P<0.05).There was no significant difference among frankfurters in ash and protein content(P>0.05).L*value increased and a*value decreased significantly(P<0.05)with the increasing of substitution rate.Both of hardness and chewiness decreased as substitution rate increased but significantly higher than the control(P<0.05).Springiness,cohesiveness and resilience significantly increased with the increasing of substitution rate(P<0.05).Sausages formulated with pre-emulsions(75%and 100%replacer)had similar(P>0.05)springiness but higher resilience with the control(P<0.05).Compared with the control,sausages with the substitution rate of 50%,75%and 100%had higher cohesiveness(P<0.05).Cooking loss and expressing loss significantly increased with the increasing of substitution rate but lower than the control(P<0.05).T23 relaxation time increased from 57.22 ms to 64.57 ms,immobile water increased and bulk water decreased.Frankfurters formulated with ultrasound emulsion had homogeneous fine three-dimensional network textural property with smaller emulsion droplet.Ultrasound treatment can produce much smaller pre-emulsified emulsion droplets than conventional homogenization.Good water and fat absorbed and binding capacities and eating qualities can be achieved by incorporating ultrasound pre-emulsified emulsion stabilized using sodium caseinate in frankfurter-style sausages.In conculsion,pre-emulsified emulsion treated with ultrasound could reduce the particle size,improved emulsification stability,enhanced the interaction with myofibrillar protein,increased G' of myofibrillar protein composite gel,enabled better textural characteristics,and improved water-and fat-binding capacities of the emulsion-type meat products.