Microwave-assisted phosphorylation of soybean protein isolates and their physicochemical properties

Abstract

Wang X.B., Chi Y.J. (2012): Microwave-assisted phosphorylation of soybean protein isolates and their physicochemical properties. Czech J. Food Sci., 30: 99-107.In order to improve the functional properties of soybean protein isolates (SPI), microwave-assisted phosphorylation (MAP) was applied. The result showed that after microwaving at 600 W for 3 min, the phosphorylation level of SPI reached 35.72 mg/g, emulsifying activity and stability were increased 2 times and 1.4 times, respectively, the solubility was increased by 26.0% and the apparent viscosity was decreased by 13.5%. The charge density, content of sulfhydryl groups, and surface hydrophobicity increased significantly. The infra-red spectroscopic analysis indicated PO 4 3-primary and lysine residues for phosphoric acid esterification. The change of amide bond Ι and fluorescence spectrum of variation suggested that the MAP made the secondary and tertiary structures of SPI into a compact conformation. Compared to the regular phosphorylation, the preparation time applied in MAP of SPI was much shorter. These results indicated that MAP can be used as an efficient method to improve the functional properties of SPI.

Functional properties and structural characteristics of phosphorylated pea protein isolate

“…So far, no one has phosphorylated PPI, so our results can only be compared with other protein phosphorylation results. Wang & Chi () had phosphorylated SPI. The results showed that the solubility of SPI after phosphorylation increased by 26%, which was lower than that of our results.…”

Effects of ultrasound pre-treatment on the structure of β-conglycinin and glycinin and the antioxidant activity of their hydrolysates

“…The FTIR spectra were recorded with 64 scans at 4 cm À1 resolution from 4000 to 400 cm À1 at 25°C. The software ''Peakfit Version 4.12" was used to analyze the secondary structure of protein, and ''Gaussian peak fitting" was the algorithm used (Wang & Chi, 2012).…”

Change in texture improvement of low-fat tofu by means of low-fat soymilk protein denaturation

“…The surface sulfhydryl group and cysteine content of soymilk is shown in Table . Some processing methods such as heating, high pressure, oxidation and reduction may lead to chemical, conformational and changes in environment of sulfhydryl groups . Compared to full‐fat soymilk (20.75 µmol g −1 ), low‐fat soymilk had a similar content, 19.30 µmol g −1 , of surface SH group ( P > 0.05).…”

“…Some processing methods such as heating, high pressure, oxidation and reduction may lead to chemical, conformational and changes in environment of sulfhydryl groups. 24 Compared to full-fat soymilk (20.75 μmol g −1 ), low-fat soymilk had a similar content, 19.30 μmol g −1 , of surface SH group (P > 0.05). After the two-step heating method, the surface SH group content of low-fat soymilk increased to 26.64 μmol g −1 .…”