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摘要
Glutaminase (EC 3.2.1.5) was applied in the present work to deamidate soybean protein isolates with limited extent, and some reaction conditions were selected. Three deamidated soybean protein isolates products with degree of deamidation of 3.5, 5.6, and 6.6% were prepared with reaction conditions as follows: soybean protein isolates concentration of 5% (w/v), glutaminase addition level of 400 U/kg soybean protein isolates, reaction temperature of 37 degrees C, and reaction times of 12, 24, and 36 h, respectively. SDS-PAGE and size exclusion chromatography analysis showed that glutaminase exhibited weak ability to catalyze the hydrolysis of the peptide bonds in soybean protein isolates. The results indicated that the deamidated soybean protein isolates prepared showed improved solubility in a pH range of 3 to 10, and had higher emulsion stability on the oil-in-water dispersions when compared to the original soybean protein isolates, but had poor emulsifying activity. Rheological assay revealed that the suspensions prepared by the deamidated soybean protein isolates products showed higher apparent viscosity, and the values of apparent viscosity depended on the degree of deamidation of the deamidated soybean protein isolates product and the addition level of Ca2+ in the suspensions. The storage modulus G' and viscous modulus G '' of the prepared suspensions gave similar behaviors as apparent viscosity. Three deamidated soybean protein isolates products prepared contained better iron (II)-chelating activity than the original soybean protein isolates as the evaluated index showed an increase of 19 to 30%. Limited deamidation of soybean protein isolates by glutaminase showed beneficial impacts on the selected properties of deamidated soybean protein isolates totally, and might be served as a practical approach to prepare multifunctional ingredients for the food industry.
- 出版日期2012
- 单位东北农业大学
