ROBERT A. EVANGELISTA

CONVERSION of MEMBRANE PROCESSED WHEY into PROTEIN and ETHANOL using IMMOBILIZED YEAST FERMENTATION

HOME Please click the camera icons to view photos.

Cheese whey, the green-yellow waste liquid that remains after the curd is separated from whole or skim milk, contains almost all of the water, salts, and milk sugar or lactose, and about twenty five percent of the protein in the original milk. The purpose of this research project was to convert a dairy waste, cheese whey, into a high value added food product, whey protein concentrate, and a liquid fuel, ethyl alcohol or ethanol. Three process steps--- ultrafiltration, reverse osmosis, and fermentation---transformed whey into “whey wine,” the end point of this research.

 

Ultrafiltration

Ultrafiltration (UF) is a semi-permeable membrane process, like the lining of your lungs, which allows small molecules to pass or permeate the membrane, called the permeate, and retains and concentrates larger molecules behind the membrane, called the retentate or concentrate. The UF permeate contained water, salts and lactose; the retentate or concentrate was whey protein concentrate. The protein in whey protein concentrate has a higher protein efficiency ratio, the mix of amino acids as needed by the human body, compared to the original milk or cheese and is one of today’s “superfoods.”

 

Reverse Osmosis

Like UF, reverse osmosis (RO) is also a semi-permeable membrane process, which allows molecules smaller in size or having a certain chemical characteristic to permeate the membrane, while retaining and concentrating molecules larger in size or of a different chemical characteristic. The RO permeate was pure water that could be discharged directly to the environment. The RO retentate or concentrate was called whey permeate concentrate, the material that permeated the ultrafilter and was subsequently concentrated by reverse osmosis. Whey permeate concentrate, with its concentrated lactose and salts, was the substance fermented into ethanol.

 

Immobilized Yeast Fementation

Fermentation is a biological process whereby a microorganism, a yeast in this research, performs the metamorphosis of lactose into ethanol. Shake flask studies, containing traditional free yeast, tested the feasibility of converting whey permeate concentrate into ethanol. In the next phase, a selected type of yeast was immobilized and placed into a bioreactor. The immobilized yeast bioreactors had distinct advantages for the rapid processing of whey into ethanol.

 

The application of this research will convert a traditional linear industrial process into a cyclic process, much like nature.

 

More Information

R. Evangelista, Conversion of Membrane Processed Whey into Protein and Ethanol using Immobilized Yeast Fermentation. Prepared for the U.S. Department of Energy, 1983. PDF 5.7 MB

Note: Acrobat PDF file is best viewed with Mozilla Firefox or Apple Safari browsers.