Preparation Of Pickering High Internal Phase Emulsion Stabilized By Modified Glycinin Particles And Its Application As Fat Replacement In Sausages

Pickering high internal phase emulsion has important application value and broad application prospect in low-fat meat products.The stability of emulsion is the key to affect the quality of low fat meat products.Therefore,in this paper,the combined modified glycinin particles by heating-ultrasonic-p H migration was taken as the research object to prepare the Pickering high internal phase emulsion with good stability,and then the Pickering emulsion was applied to the production of sausages.The main results are as follows:1.The optimal concentration of modified glycinin particles and oil-phase volume fraction for the preparation of Pickering high internal phase emulsion was studied through evaluating emulsifying activity(EAI)and emulsifying stability(ESI),particle size,rheological properties,micromorphology,interfacial protein content,intermolecular interaction force,secondary structure,oxidative stability and appearance changes.The results showed that,when the protein particles concentration was 4%and the oil-phase volume fraction was 80%,the modified glycinin particles have the highest EAI(7.36 m~2/g)and ESI(99.0%).Moreover,the particle size of the emulsion is the smallest(5207.5 nm)and the apparent viscosity and storage modulus(G’)are the largest,with the emulsion droplets evenly distributed as shown by CLSM.Meanwhile,the content of interfacial protein in Pickering emulsions was the highest(74.88%).The main intermolecular interactions were ionic bonds,disulfide bonds and hydrophobic interactions.The secondary structure content wasα-helix,random coil,β-sheet andβ-turn in descending order.The sulfhydryls of the Pickering emulsion stabilized by 4%glycinin particles with 80%oil-phase volume fraction increases by95.38%,while the carbonyls decreased by 45.27%.At this time,the TBARS value was the smallest(1.2769 mg/kg).The emulsion showed no creaming and demulsification phenomenons when stored at 4℃for more than 300 d,indicating the storage stability is good.2.The effects of external conditions(p H,ionic strength,temperature,freeze-thaw cycles and cryopreservation)on the stability of Pickering high internal phase emulsions were studied with EAI,ESI,particle size,rheological properties,degree of fat oxidation and appearance changes as evaluation indicators.The results showed that,when the p H was 2,8 and 10,the appearance of the emulsion stabilized by 4%glycinin particles with 80%oil-phase volume fraction had no obvious changes when stored at 4℃for 300 d.Meanwhile,the EAI(12.08m~2/g)and ESI(82.15%)of the glycinin particles were the highest,the particle size was the smallest(4736.44 nm),and the rheological properties were the strongest.With the ionic strength increased from 0.1 M to 0.6 M,the EAI and ESI of the emulsion respectively decreased 1.12 times and 0.71 times,while the particle size increased by 0.19 times.However,the emulsin was stable when stored at 4°C for up to 300 d.When heated at 100°C for 5-60min,the particle size of the emulsion increased by 0.7 times,and the emulsion was stable with storing at 4°C for at least 300 d.When the emulsion underwent repeated freeze-thaw cycles(freezing at-20℃for 48 h,defreezing at room temperature for 4 h),the particle size of the emulsion increased significantly(P<0.05)with the increase of the number of freeze-thaw cycles(0～5 times).Flocculation occurred at the third freeze-thaw cycle.The particle size of the emulsion increased by 19%and the TABRS increased by 0.72 times during low temperature storage(4℃,15 d),but the appearance of the emulsion did not change significantly.It can be seen that the Pickering high internal phase emulsion stabilized by modified glycinin particles was well resistant to extreme acidity and alkalinity(p H2,8,10),high ionic strength(0.6 M),high temperature(100°C,60 min),freeze-thaw cycles(<3 times),and showed strong anti-fat oxidation ability when stored at 4℃.3.The effects of Pickering high internal phase emulsion replacing pork backfat with different proportions on the quality of sausages were studied using texture,tenderness,microstructure,cooking loss,sensory evaluation,color and fat oxidation degree as evaluation indexes.The results showed that,when the emulsion substitution ratio was 100%,the sausage was rich in viscoelastic network structures with,significantly improved texture properties(P<0.05),the disappearance of holes inside as shown by SEM,a highest shear stress of 7.06 N and a lowest cooking loss of 2.26%.The sensory evaluation results further confirmed that the various indicators of emulsion substitution sausages were significantly higher than those of the control group,and the acceptability was good.The brightness L*value increased by16.5%,and the redness a*value and yellowness b*value decreased by 53.74%and 44.94%,respectively.During the storage period(4℃,15 d),the TBARS value was still significantly lower than that of the control group(P<0.05),showing strong antioxidant effect.It can be seen that the Pickering high internal phase emulsion prepared by modified glycinin particles can be used as a fat substitute in the production of sausages.In summary,the optimal concentration of modified glycinin particles and oil-phase volume fraction for the preparation of Pickering high internal phase emulsion were determined,and the influences of external conditions on the stability of Pickering high internal phase emulsion stabilized by modified glycinin particles was clarified.Low-fat sausages substituted with 100%emulsion were successfully produced.It provides new ideas and data support for the industrial production of food-grade Pickering emulsion and the development of meat products with fat substitution.