Patent ID: 7005506

Claim:
A method for preparing an albumin isolate from a substance containing albumin, the method comprising: grinding the substance to a flour; suspending the flour in an aqueous solution to form a dispersion; subjecting the flour in the dispersion to an at least two stage alkaline extraction treatment in the presence of at least one protease to extract the albumin from the flour into the aqueous solution, the protease having an activity in the alkaline extraction treatment, in both of the at least two stages pH-values of the dispersion being approximately 8 to 11.5, and temperatures of the dispersion being from approximately 30 to 60° C.; in the first stage, the flour being treated with a lower concentration of the at least one protease in relation to a weight of the albumin in the dispersion, with a pH of approximately 8 to 10 and with a temperature of about 30 to 60° C.; at the end of the first stage, the dispersion being separated into a first overflow containing albumin extracted from the flour, and a fraction of the dispersion containing the remaining flour; in the second stage, the flour remaining in the fraction of the dispersion being treated with a higher concentration of the at least one protease in relation to the weight of the albumin in the dispersion, with a pH of approximately 10.5 to 11.5 and with a temperature of about 30 to 45° C., provided it is lower than in the first stage; at the end of the second stage, the dispersion being separated into a second overflow containing albumin extracted from the flour, and a sub-fraction of the fraction of the dispersion containing the remaining flour; after separating the dispersion at the end of the second stage, the second overflow being fed back to the first stage of the alkaline extraction treatment of the flour in the dispersion; after separating the dispersion at the end of the first stage, precipitating the albumin from the first overflow using an acid solution of at least one mineral acid by lowering the pH to isoelectric point of the albumin; and neutralizing the precipitated albumin.