Functional Properties And Application In Meat Products Of Pork Liver Water-soluble Protein

As the fat substitute in low fat processing of emulsified meat products,the emulsion consisted of protein,water and planting oil,because it can reduce fat content,increase protein content and improve the fatty acid composition at the same time,has become a hot research at home and abroad in recent years.Pork liver is one of the main byproducts of pork,rich in protein,minerals and vitamins,etc.,the nutrition is extremely rich in food resources.Pork liver water-soluble protein as the main protein of liver,with good emulsification,its functional properties have not yet a more comprehensive study.In this paper,For the actual production of liver,and to provide a theoretical basis of pork liver protein,the liver and liver protein as the object of study to explore the impact of different environmental conditions on its functional properties,and further study on the emulsifying properties of pork liver protein-soybean oil,and finally the application of pork liver protein-soybean oil emulsion in low-Emulsified meat emulsion.The main findings are as follows:1.Nutritional characteristics of liver and liver protein.The ratio of essential amino acids to total amino acids in the liver water-soluble protein is more than 40%,which is a high quality protein source,beyond the WHO / FAO reference protein model.2.Effects of different environmental conditions on the functional properties of pork liver water-soluble protein.The solubility,hydrophobicity,turbidity,foaming activity and stability of the soluble protein were significantly changed with different pH,temperature,protein concentration and ionic strength(P <0.05).At pH 4-5,the solubility,foaming activity,emulsifying activity and stability of pork liver were the lowest,the turbidity and foam stability were the highest.When the temperature was 50-60 ℃,The solubility,turbidity,foaming activity and stability,the emulsifying activity and the stability of the water-soluble protein were the best.With the increase of the protein concentration,the solubility and the emulsifying activity of the protein were decreased,Activity and stability,emulsification stability showed an increasing trend.When the concentration of sodium chloride was 0.2mol/L,the solubility,foaming activity,emulsifying activity and stability of liver protein were the highest,but under the condition of high salt,solubility,foaming activity,emulsifying activity and stability increased with the increase of salt concentration.In conclusion,the amino acid composition of pork liver water-soluble protein is balanced,and the solubility,foaming and emulsifying properties are good.It is not only a high class resource of protein,its good functional characteristics also are also valuable.3.Study on the stability of protein content oil phase in protein emulsification system.With the increase of protein content,the emulsifying activity and the emulsion index of the emulsified system decreased and the emulsifying stability and apparent viscosity were significantly increasing(P <0.05).In the protein concentration of 0.125% and 0.25%,the homogenization of the emulsion was not uniform,we can clearly see unemulsified oil droplets,the final flocculation phenomenon,and the formation of unstable emulsion system;with the liver protein concentration increased,the particle size of emulsified particles gradually became smaller and the distribution was uniform,the interface protein concentration increased,the apparent viscosity and emulsifying stability increased,and the emulsion index decreased.With the increase of the oil phase,the emulsifying activity and apparent viscosity of the porcine liver protein emulsified system increased gradually,and the emulsion stability increased first and then decreased.When the oil phase volume is less than 37.5%,the emulsion index increases and the emulsion stability decreases.With the increase of the volume fraction of the oil phase,the apparent viscosity of the emulsified system increases,the emulsion index decreases,the emulsification stability increases,The oil droplet size gradually increased,when the oil phase is greater than 45%.There is a phenomenon of aggregation,because some oil droplets can not be emulsified.4.Effects of pork liver water soluble protein-soybean oil emulsion on the conversion of pork fat to low-fat emulsified meat(P <0.05).With the increase of the proportion of emulsions,the proportion of saturated fatty acids in meat emulsion decreased,and the content of saturated fatty acids in the low-salt and low-fat emulsified meat emulsion increased significantly.The ratio of unsaturated fatty acids and monounsaturated fatty acids increased to improve the fatty acid composition of emulsified meat emulsion.The L *,a * and b * values of heat-induced gel increased significantly with the increase of proportion of emulsions(P <0.05),The loss of cooking,the water loss rate and the oil loss rate decreased first and then increased.When the ratio of pork fat was more than 75%,the emulsified meat emulsion had the special smell of soybean and liver,and the acceptability was decreased.In general,low-salt low-fat emulsified meat emulsion which pork liver water soluble protein-soybean oil instead of lard,reduced the fat content,significantly improved the product’s juicy,increased protein content and unsaturated fatty acid content,and significantly improved the chemical composition of the meat and fatty acid at the same time.Sensory evaluation in the replacement of less than 75% when the difference is not significant,compared with the low salt control,cooking loss and texture also improved,but still less than high salt control.Therefore,the alternative ratio of 50% of the pork liver water soluble protein-soybean oil pre-emulsion instead of pork fat,can make the product’s chemical composition and nutritional value is improved,the product texture,sensory index are not adversely affected.