Journal of Agricultural Engineering

Soy protein isolate (SPI) were obtained through ultrafiltration using 10 kDa hollow fibre cartridge, 117.21 kPa trans-membrane pressure and 3.5 volume concentration ratio. SPI prepared by ultrafiltration possessed highest protein content (88±0.3%) and 91.09±0.84% nitrogen solubility index (NSI) as compared to 84±0.5% protein content and 19.29±0.74% NSI for acid precipitated and 85±0.5% protein content for commercially available SPI. Ultra filtered SPI also possessed highest value of emulsion stability (ES) of 51.96±1.42%, whereas commercially available SPI exhibited the least value of 48.38±0.015 per cent. Highest value of oil absorption capacity (OAC) was 2.15±0.04 g.g⁻¹ of protein for ultra-filtered, followed by 1.94±0.01 g.g⁻¹ of protein for commercially available, and 1.73±0.04g.g⁻¹ of protein for acid precipitated SPI. The hydrophilic lipophilic index (HLI) values for both ultra-filtrated and commercial SPIs were more than 2, indicating hydrophilic-lipophilic balance of proteins. However, water absorption capacity (WAC) and emulsion capacity were less for ultra-filtered sample as compared to commercially available counterpart. Commercially available SPI had highest value of 6.84±0.08 ml.g⁻¹ of protein, whereas it was least at 1.67±0.016 ml.g⁻¹ of protein for acid precipitated SPI.