Effect of xanthan gum on enhancing the foaming properties of soy protein isolate

The foaming properties of whey protein isolate (WPI) in the presence of xanthan gum (XG) were investigated. XG dispersion did not exhibit any foaming properties. The optimal foaming overrun (FO), or the amount of air incorporated into the dispersion, was obtained from the dispersion of 5% WPI and 0.05% XG at 949%. This WPI-XG dispersion had a significantly higher overrun than that of WPI (868%) or egg white (879%) (P<0.05). Optimal foam stability (FS) of 216 min was obtained at 5% WPI and 0.2% XG; however, the overrun was reduced slightly (844%). XG increased stability to 15 times that of WPI alone. The overrun of 5% WPI plus 0.05% XG was further increased to 1343% when 1 M NaCl was added (P<0.05). However, FS (51 min) was significantly reduced. A significant increase in the FO of 5% WPI plus 0.05% XG (1081%) was observed when pH was adjusted to 5.0 with no significant change in FS (56 min) (P<0.05). The FO (1457%) was significantly increased (P<0.05) when the WPI-XG was heat treated (55°C for 5 min). WPI-XG dispersions at acidic pH and temperatures below 85°C have a variety of potential applications in products such as protein beverages, angel food cake, and unique infant formulas.