A soy protein product, which may be an isolate, produces transparent
heat-stable solutions at low pH values and is useful for the
fortification of soft drinks and sports drinks without precipitation of
protein. The soy protein product is obtained by extracting a soy protein
source material with an aqueous calcium salt solution to form an aqueous
soy protein solution, separating the aqueous soy protein solution from
residual soy protein source, adjusting the pH of the aqueous soy protein
solution to a pH of about 1.5 to about 4.4 to produce an acidified clear
soy protein solution, which may be dried, following optional
concentration and diafiltration, to provide the soy protein product.