1Ph. D. Scholar, Indian Agricultural Research Institute, New Delhi (Central Institute of Agricultural Engineering, Bhopal campus)
2Principal Scientist, Centre of Excellence of Soybean Processing and Utilization Unit Central Institute of Agricultural Engineering, Bhopal
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.
Soy protein isolate, ultrafiltration, acid precipitation, functional properties
