Construction Of Soybean Peptide Compound Emulsifier And Application In β-carotene Embedding

The soybean peptide aggregates(SPA)produced by the enzymatic hydrolysis are usually thrown away or made into animal food,causing waste of resources.In recent years,food safety issues and rapid population growth have brought more challenges to the food industry,they have driven the food industry to develop more efficient and high-value utilization of food waste or by-products.Soybean peptide particles(SPP)formed by self-assembly have excellent particle characteristics,this kind of emulsion is prepared and applied to embedding of bioactive substances.However,the delamination phenomenon of SPP emulsion inevitably occurs.In order to improve the anti-delamination stability of SPP emulsion,firstly,the soybean protein isolate(SPI)was hydrolyzed with alkaline protease Alcalase for 6 hours to obtain SPA,the SPA was self-assembled by ultrasound to form SPP,and the pH-stat method was used to prepare soybean peptides with DH of 0%,1%,2%,5%,and 10%.The gel imager,transmission electron microscope(TEM),particle size analyzer,intelligent modular rheometer and other methods were used to characterize SPA,SPP,and soybean peptides with different degrees of hydrolysis,to study solubility and emulsification of soybean peptide /SPP compound emulsion.At the same time,the ratio of soybean peptide with different degrees of hydrolysis and SPP were 0.1: 1,0.2: 1,and 0.4: 1 respectively,and a soybean peptide / SPP composite emulsion was prepared,the layered index,droplet size,and appearance of the composite emulsion,microscopic morphology of droplets,oxidative stability,surface charge were observed.Finally,β-carotene was embedded in soybean peptide composite emulsion with excellent properties,β-carotene content,carotene embedding rate,light and heat stability and storage stability were used as multiple indices to study β-carotene in different composite emulsions.The main findings are as follows:(1)SPA is composed of many low molecular weight peptide chains,with a large particle size of about 1768.1 nm;SPP particles after ultrasound are round and have a rough surface,with a particle size of 638.9 nm,the apparent viscosity of the solution is greater than SPA.Compared with SPP,the solubility of soy peptide / SPP composite emulsifiers shows a increasing trend when degrees vary,the solubility of DH 10% / SPP composite emulsifier is the largest;and the emulsification stability ratio of DH 0% soybean peptide composite emulsifier increased by about 60.81%.The emulsification stability of DH 1% composite emulsifier was the highest among the five composite emulsifiers.The soybean peptides of DH 2%,DH 5%,and DH 10% did not significantly improve emulsifier stability of emulsifier.(2)When the ratio of both soybean peptide and SPP is 0.1: 1,the soybean peptide composite emulsion with DH of 0% and 1% can better improve the anti-layering stability of the emulsion,in which the soybean peptide compound emulsion with DH of 1% has the best properties,good anti-oxidative stability,anti-flocculation and coalescence stability.The absolute value of the potential is higher,reaching 18.67 mV,and the interface protein adsorption rate is increased to 98.82%,which is higher than SPP emulsion.It is higher for 3.41%,and the viscosity of the whole system is high.When the ratio of soybean peptide and SPP is 0.4: 1,the delamination index of the composite emulsion is significantly increased,the droplet size is large,flocculation is easy to occur,the emulsion is easily oxidized,and the anti-delamination stability is poor.In addition,the anti-layering stability of the composite emulsion showed a decreasing trend with the increase of the degree of hydrolysis of the soybean peptide,and the layering stability of the 10% soybean peptide composite emulsion was the worst.(3)Compared with the SPP composite emulsion,the soybean peptide composite emulsion can improve the embedding rate of β-carotene.the DH 0% soybean peptide composite emulsion increased by 5%,and the DH 1% composite emulsion increased by 6%;The composite emulsion can significantly improve the photostability of β-carotene,the soybean peptide composite emulsion of DH 1% in the dark or indoor light shows excellent antioxidant capacity as well as improving the retention rate of β-carotene.,under daylight conditions,although it can be improved to a certain extent,the effect is not significant;in addition,the soybean peptide composite emulsion can significantly improve the thermal stability of β-carotene.At 25 ℃ and 37℃,the soybean peptide compound The β-carotene content in the emulsion changed little,and the β-carotene content in the compound emulsion decreased rapidly at 55℃.This article provides a theoretical basis for better utilization of soy peptide aggregates and improvement of the properties of bioactive substances.