Studies On The Preparation And Emulsifying Properties Of Natural Flax Protein Emulsifier

At present,with the improvement of living standards,people’s requirements on the quality of life are also gradually improved.Food occupies an indispensable position in people’s life.After simple dietary conditions are satisfied,people begin to pursue green,natural and healthy food.Safe and non-toxic natural food additives gradually become the focus of researcher.Plant protein is an important resource for the development of natural emulsifiers due to its good emulsifying properties,wide source,low cost,complete kinds of amino acids and rich nutrition.In this paper,plant seed proteins with strong emulsifying ability were screened from 8 plant seeds with high protein content,including flax,pumpkin,Chinese prickly ash,Perilla,ginkgo,rape,grass pea and cowpea.And protease was used to prepare emulsifying liquid with good emulsifying characteristics.Then the preparation technology and influencing factors of enzymatic hydrolysis products were studied in order to provide more theoretical basis for the application of plant protein as natural emulsifier in food production and processing.The main research contents and results of this paper were as follows:(1)Seeds of flax,pumpkin,Chinese prickly ash,Perilla,ginkgo,rape,grass pea and cowpea were dried and crushed.Petroleum ether was used as the extraction agent for degreasing,and phosphate buffer solution was used to extract plant seed proteins.Then the emulsification and stability of these eight plant seed proteins were compared.The results showed that the best emulsifying capacity of these eight plant seed proteins was flax protein which was 57.89 m~2/g.Among the flax isolated proteins,the emulsifying activity index of the alcohol soluble protein was the highest,68.94 m~2/g.(2)Firstly,alcoholic flax protein was hydrolyzed with 3 kinds of proteases.Then the emulsifiability of the enzymatic hydrolysis products was determined and compared with the non-hydrolyzed alcohol soluble protein.The result of enzyme screening was alkaline protease.Then alkaline protease was used to hydrolyze the alcohol soluble flax protein,and the effects of single factor on the emulsifiability of enzymatic hydrolysis products were studied.Finally,the response surface test was used to optimize the enzymatic hydrolysis process of alcoholic flax proteolytic products.The results showed that the factors affecting the emulsifying activity index of the products were enzymatic hydrolysis time>enzymatic ratio>enzymatic pH.The optimum process combination of enzymatic hydrolysis were as follows:the time of enzymatic hydrolysis was 2.2 h,the enzyme base ratio was 4%,temperature was 45℃and the value of pH was 8.0.Under these conditions,the emulsifying activity of peptides was the best.EAI was 86.23 m~2/g.(3)The effects of different pH values,NaCl concentration,polypeptide concentration and oil phase volume fraction on emulsifying activity were studied.The results showed that alkaline protease was used to hydrolyze the protein within a certain pH range.The increase of pH value was helpful to the emulsifying ability of enzymatic hydrolysate.NaCl could weaken the emulsifying activity of enzymatic hydrolysates.In a certain range,the emulsifying activity of enzymatic hydrolysate was decreased with the increase of polypeptide concentration.In a certain range,with the increase of oil volume fraction,the emulsifying activity index of enzymatic hydrolysis products was increased.