Covalent attachment of fenugreek gum to soy whey protein isolate through natural Maillard reaction for improved emulsion stability

Soy whey protein isolate (SWPI)-fenugreek gum (hydrolyzed and unhydrolyzed) conjugates were prepared by Maillard-type reaction in a controlled dry state condition (60 °C, 75% relative humidity for 3 days) to improve emulsification properties. Fenugreek gum was partially hydrolyzed using 0.05 M HCl at 90 °C for 10 min (HD10), 30 min (HD30) and 50 min (HD50) to examine if molecular weight had an effect on the emulsifying properties. The formation of SWPI-fenugreek gum conjugates was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Measurements of particle size distribution and average particle size have shown that conjugation of SWPI-fenugreek gum at 60 °C for 3 days was enough to produce relatively small droplet sizes in oil-in-water (o/w) emulsions. A ratio of 1:3 and 1:5 of SWPI:fenugreek gum was more effective in stabilizing emulsion compared to 1:1 ratio. Unhydrolyzed fenugreek gum conjugates exhibited better emulsifying properties compared to partially hydrolyzed fenugreek gum conjugates. The order of the conjugates in lowering the particle size of emulsions was as follows: SWPI-unhydrolzed fenugreek gum > SWPI-HD10 > SWPI-HD30 > SWPI-HD50. © 2012.