The foaming properties of whey protein isolate (WPI) in the presence of xan
than gum (XG) were investigated. XG dispersion did not exhibit any;foaming
properties. The optimal foaming overrun (FO), or the amount of air incorpor
ated 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 t
han that of WPI (868%) or egg white (879%) (P < 0.05). Optimal foam stabili
ty (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 WP
I 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%) wa
s 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 (Pi 0.05) when
the WPI-XG was heat treated (55 degrees C for 5 min). WPI-XG dispersions a
t acidic pH and temperatures below 85 degrees C have a variety of potential
applications in products such as protein beverages; angel food cake, and u
nique infant formulas.