Research On Egg White Protein-based Fat Substitute And Its Application In Ice Cream

Fat is not only an important source of fatty acids,but also one of the main factors affecting the taste and flavor of food such as gloss,hardness,elasticity,viscosity and lubricity.However,high fat intake leads to high calories,so fat-free and low-fat foods are becoming more and more popular.Simply reducing the fat content of the food will make the product taste rough,so the development of low-calorie fat substitutes is getting more and more attention.Protein is one of the commonly used raw materials for fat substitutes.As the main material in food,egg white is rich in a variety of proteins.Egg white-based fat substitutes can enhance the uniformity of low-fat foods and play an important role in food processing and production.At present,there are relatively few studies on egg white protein-based fat substitutes.In this paper,the conditions of egg white-based fat substitutes were optimized by single factor and response surface combination.The mechanism of egg white and xanthan gel formation was investigated by infrared spectroscopy(FTIR)and scanning electron microscopy(SEM).The product is applied to ice cream to reduce the fat content of the product.The research conclusions are as follows:(1)The effects of polysaccharide type and addition amount,total gel solid content,heating temperature,heating time and gel micronization time on the gel properties of egg white gel were investigated by single factor and response surface optimization experiments.The test results show that the optimum process parameters for preparing egg white-based fat substitutes are 6% total solid content,xanthan gum concentration 0.06wt%,gelation temperature 90 oC,heating time 25 min and micronization time 10 min.The substitute has rheological properties similar to cream.(2)The low field nuclear magnetic resonance(LF-NMR),scanning electron microscopy(SEM)and infrared spectroscopy(FTIR)were used to investigate the gel formation mechanism of xanthan gum(XG)and egg white(EW).The results showed that xanthan gum changed the secondary structure of egg white protein,which ?-helix was decreased and ?-sheet was increased.And the content of disulfide bond was increased.The hardness,viscosity and elasticity of egg white gel were improved.The change of egg white gel viscosity is mainly due to the interaction of xanthan gum and ovalbumin.The partial electrostatic interaction between xanthan gum and ovalbumin was observed,which the electrostatic repulsion of the mixed gel was reduced and the content of ovalbumin disulfide bonds was increased,thereby enhancing the viscosity of the egg white protein gel.(3)The purpose of this research was to investigate egg white-xanthan gum(EW-XG)complex as a fat substitute to reduce the fat in high-fat ice cream to get low fat ice cream.The effect of lipid-replacement in ice cream was analyzed by physicochemical properties measurement,sensory evaluation and microstructure observation.The results showed thatoverrun was increased from 54.9% to 72.6% and melting rate was decreased from 48.32%to 24.3% when 15% fat substitute was added.And the amounts of bubbles and fat aggregation were also increased.Therefore,ice cream was best accepted at addition of15% fat substitute.