Studies Of The Modification Of Alcohol Leached Soy Protein Concentrate By Ammonia Treatment

Modification of ALSPC using ammonia as alkaline reagent through stirring, homo- geneous, flash depressing temperature, vacuum condensation, spray dryness was investigated in this paper. In order to obtain a functional ALSPC(FSPC), some single factor and orthogonal experiments changing protein concentration,ammonia contents and the mixing temperature were carried out. The self-made ALSPC was modified according to jinhai ALSPC modification conditions. The optimal modification conditions of Jinhai ALSPC were protein solution concentration 8% , the addition of ammonia 0.57%(w/w), stirring time 30min and temperature 80℃. Compared to the optimal modification conditions of Jinhai ALSPC , the addition of ammonia to the self-made ALSPC was only 0.38%(w/w).The structure and function of soybean protein is relative, so the functions can be predicted through the structure, at the same time, the composition and structure can also be understood by the functions. The surface hydrophobicity, sulfhydryl group, disulfide bond and protein relative molecular weight distribution of Jinhai ALSPC treated with ammonia were characterized. Furthermore, the correlation analysis between structure and functional properties was also discussed in the paper. The results have shown that ammonia treatment on ALSPC had significant impact on the surface hydrobicity and protein relative molecular weight distribution,but no obvious impact on the sulfhydryl group and disulfide bond. There were positive correlation between NSI and surface hydrophobicity and soluble protein aggregates, but negative correlation between NSI and sulfhydryl and disulfide bond. There were positive correlation between emulsion and surface hydrophobicity and soluble protein aggregates,while negative correlation between emulsion and sulfhydryl and disulfide bond. There were no significant correlation between gel and surface hydrophobicity,sulfhydryl group, disulfide bond and soluble aggregates.Sensory analysis results have shown that ammonia modification can improve the flavor & smell of ALSPC. In addition, the ash content, the solubility at different pH and the flavor of the FSPC were determined. And the results have revealed that the ash content decreased with more ammonia addition, aldehydes, nonanal, benzaldehyde and other peculiar smell compents of modified ALSPC was reduced. This has great implication significance to food industuy.