| Whey protein can form amyloid fibril polymer under low pH and low ionic strength and high temperature for a long time.In the formation process,fibril polymer first undergoes primary nucleation process to form homogeneous nuclei(primary nuclei).After undergoing secondary nucleation process to form mature fibril(secondary nuclei),there are many studies on the mechanism of fibril self-assembly,polymerization kinetics,but lack of two nuclear-induced functional studies.Therefore,this subject has studied the treatment of whey protein conc entrates in different ways to change their structure,so that the polymerization forms conventional polymers and fibril polymers,through thiosulfurin T(Th T),transmission electron microscopy(TEM),surface hydrophobicity,particles Analysis of the diameter and Zeta potential,to explore the difference in the emulsifying properties of the two polymers,as well as the different size of the polymer,the amount of nuclei induced fibril changes,the different pH environment and the effect of different fibril polymer formation on its emulsification,The effect of fibril concentration and fibril formation on the stability of the prepared Pickering emulsion was investigated.The specific research results are as follows:The difference in emulsifying properties between fibril polymer and conventional polymer: TEM results show that the fibril polymer formed by WPC spontaneously is an elongated rod-like structure,which is completely different from the larger cluster of conventional polymers,and the formation of polymer will be The emulsification activity and emulsion stability of WPC are improved,and the emulsification activity and emulsion stabil ity of the fibril polymer are significantly higher than that of the conventional polymer,which is 1.39 times and 1.60 times that of the conventional polymer,and the potential increase is 1.98 times that of the conventional polymer.Surface hydrophobicity is more advantageous than conventional polymers to improve emulsifying properties.The effect of the size of the fibril polymer on the emulsifying property: high-speed shearing of the fibril can break the fibril into small fragments,and the emulsification of the fibril can be effectively improved;after the fibril is subjected to ultrasonic treatment at 19 k HZ,the structural damage is small,Th The change of T is not obvious,and the effect on its emulsification is not obvious.The fibril is hydrolyzed by alkaline protease,the structure is destroyed into a short fibril segment,Th T is decreased by 26.1%,and the emulsification activity and emulsification of the fibril after hydrolysis for 5 h.Stability decreased by 36.32% and 57.63%.The effect of nucleation-inducing on emulsification: nuclear induction can increase the speed of WPC fibril formation and fibril volume,and effectively improve the emulsification.The emulsification activity of WPC induced by homogeneous and secondary nuclei is 1.12 times and 1.20 times that of WPC spontaneously.Sex is 1.12 times and 1.17 times more spontaneous than WPC.The fluorescence intensity of WPC 2 h induced by homogeneous nuclear induced WPC around 3 h and secondary nuclei was consistent with the Th T value of WPC spontaneously formed for 10 h,and the Th T value of WPC 10 h induced by homogeneous nuclei and secondary nuclei was The WPC spontaneously increased by 1.22 times and 1.21 times,and the potential increment increased by 2.14 mv and 2.41 mv,respectively.The nano-scale and micro-scale particle size increase was significantly increased compared with WPC spontaneously;the fibril induced by alkaline protease was enhanced.From the induction of 2h,the emulsification activity and emulsion stability increased with the increase of the degree of hydrolyzed fibril.When induced for 10 h,the emulsification activity and emulsion stability of the fibril hydrolysate hydrolyzed for 5h were 1.96 hydrolysis 0h.With a magnification of 3.58 times,the fluorescence intensi ty,particle size increase,and potential increase also gradually increase.Effect of pH on whey protein concentrate emulsion: pH near the isoelectric point(5.0)reduces the emulsifying properties of conventional milk and fibril polymers,but nuclear induction is more resistant to isoelectric points than conventional milk and WPC spontaneous At this time,the emulsification activity induced by WPC spontaneous,secondary induction and fibril hydrolysate was 1.59,1.78 and 1.86 times of that of conventional milk,but the emulsion stabilization time(emulsion stability reached 50%)was less than 30 min.When the pH is far from the isoelectric point,the emulsifying property can be effectively improved at a lower pH or a higher pH,and the emulsifying property is pH 5.0 < pH 2.0 < pH 12.In an alkaline environment,the higher the pH,the stronger the emulsifiability,and the emulsification activity and emulsion stability are maximized at pH 12.0.The increase of fibril content by nuclear-induced WPC can improve the emulsifying property.The emulsifying property of WPC induced by fibril hydrolysate is obviously higher than that of conventional milk,WPC spontaneous and secondary nuclear induced WPC,and the emulsion can be allowed to stand for 27 hours under the e nvironment of pH 12.0.Half of the initial stability was 7.71 times,1.23 times,and 1.08 times that of conventional milk,WPC spontaneous and secondary nuclear induction.Comparison of performance differences between different fibril formation methods: The formation of fibril polymer by nuclear induction can significantly increase the amount of fibril formed by WPC compared with WPC,thereby improving the emulsifying property,and the fibril hydrolyzate induces a greater increase.The emulsification activi ty of the secondary nuclear induction and the fibril hydrolyzate induced fibril-forming polymer formation was 1.20 times and 1.26 times that of WPC spontaneously,and the emulsion stability was 1.17 times and 1.35 times that of WPC spontaneously.Th T value,nano-scale particle size increase and potential increase are all nuclear-induced fibril-forming polymers.Compared with WPC,the fibril hydrolysate is induced in a higher way than nuclear induction,while fibril hydrolyzate induces micron-sized particle growth.The amount is lower than the core induction,and the formed fibril size is smaller,but the fibril amount is higher,and the ability to improve the WPC emulsifiability is stronger.Effect of fibril polymer on the stability of stable Pickering emulsion: When the particle concentration is 10mg/m L-50mg/m L,the milking index of Pickering emulsion gradually decreases with the increase of fibril concentration,at low concentration,milky The liquid is more likely to precipitate fat and water phase;the stability of the Pickering emulsion can also be improved by increasing the amount of fibril by nuclear-induced WPC,wherein the Pickering emulsion induced by the fibril hydrolysate is the most stable.At a particle concentration of 50 mg/m L,the height of the emulsion layer after 28 days of standing on the Pickering emulsion induced by WPC and fibril hydrolyzate induced by WPC and fibril hydrolysate was 1.26 times and 1.03 times higher than that of WPC spontaneous mode. |
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