The Modification Of Insoluble Soy Peptide Aggregate(ISPA):Application In The Whipped Cream

Whipped cream is a whipped foaming product,the emulsion needs to maintain relative stability before whipping.Casein is a mian component of whipped cream,which has a high price.During the enzymatic hydrolysis of soy protein,the undesirable insoluble soy peptide aggregates(ISPA)is formed.The ISPA is hard to be utilized in virtue of its poor solubility,but it is rich in protein and has high nutrition,which has the potential value.The purpose of this paper is to improve the solubility,emulsifying ability and foaming ability of ISPA,then replace partial casein for preparing whipped cream in good quality,improving the added value of ISPA and reducing the costs of whipped creamFirstly,different pretreatments(sonication,homogeneous)combined with alkaline dissolution(pH10,pH12)were used to modify ISPA,and the changes in the structure and functional properties of ISPA were studied.Then the oil-water interfical properties and emulsion properties of modified ISPA were explored.Finally,the effect of the ratio between modified ISPA and casein on the quality of whipped cream was investigatedPhysical-alkaline treatment apparently changed the structure and functional properties of ISPA.The structure of modified ISPA was looser,the surface hydrophobicity was improved,and the solubility and emulsifying ability were enhanced.The ISPA had better foaming properties after treated by alkaline at pH10(1.73?2.24 times of commercial SPI),better emulsifying ability at pH12(1.26?2.02 times of commercial SPI).Compared with single alkaline treatment,ultrasonic pretreatment was helpful to enhance the foaming properties of ISPAPhysical-alkaline treatment distinctly influenced the interfacial properties and emulsion properties of ISPA.The interfacial activity of ISPA treated with alkaline at pH12 was lower than that at pH10,but formed a stronger viscoelastic interfacial film.Ultrasound and homogeneous pretreatment were beneficial to enhance the interface film.The electrostatic repulsion between the droplets of emulsion stabilized by modified ISPA was enhanced,the droplets were reduced and distributed more uniform.Compared to SPI,the stability of emulsion prepared by ISPA modified at pH 10 was similar with it,the stability of emulsion prepared by ISPA modified at pH 12 was betterThe ratio between modified ISPA(ultrasonic-pH10 treatment)and casein significantly affected the quality of whipped cream.For the sensory quality of whipped cream,casein group(without ISPA)was the best,untreated ISPA group(10%casein was replaced with untreated ISPA)was the worst.With the ratio of modified ISPA and casein increased,the particle size in emulsion increased,the apparent viscosity and storage modulus(G')increased first and then decreased,the loss tangent(tan?)and whipping time decreased first and then increased,the sensory quality of cream first increased and then decreased,therefore the best ratio between modified ISPA and casein was 1:4,here all the indicators of cream reached peak value,and the sensory quality was better.The results of correlation analysis showed that G' and tan? of the emulsions had a significant effect on the whipping time.