United States Patent Number: 4,689,151, August 25, 1987. 11 pages. Also available from the United States Patent and Trademark Office. Website: http://www.uspto.gov
NOTE: At the time of publication, the author Rafael Riménez-Flores was affiliated with the University of California - Davis. Currently, May 2008, he is Professor of Dairy Science at California Polytechnic State University - San Luis Obispo, CA.
A method of removing penicillin G and/or pharmaceutical antibiotics which contaminated milk by:
(a) Subjecting the contaminated milk to an ultrafiltration process which produces a permeate containing the contamining antibiotic and a retentate comprising milk proteins and fats.
(b) Adding a non-antibiotic containing retentate diluting (washing) aqueous fluid including uncontaminated ultrafiltered milk permeate, uncontaminated whole milk, uncontaminated skim milk, or uncontaminated acid or sweet whey, or a mixture thereof to the retentate to dilute the retentate.
(c) Subjecting the diluted (washed) retentate to the ultrafiltration process from additional antibiotic containing permeate thereby forming a milk product comprising retentate having a reduced level of or substantially free of antibiotics.
(d) After the last dilution (wash) step and the milk retentate is returned to selected protein concentration the retentate is reconstituted with either uncontaminated ultrafiltrated milk permeate, or uncontaminated whole milk, or uncontaminated skim milk, or acid whey or sweet whey.