Adsa Logo White Adsa Title White

Valorization of Greek yogurt acid whey using filtration and acid-catalyzed lactose hydrolysis.

M. Lindsay




Valorization of Greek yogurt acid whey using filtration and acid-catalyzed lactose hydrolysis.
M. Lindsay*1, M. Molitor3, K. Huang1, C. Maravelias1, J. Dumesic1, S. Rankin2, G. Huber1. 1Department of Chemical and Biological Engineering, University of Wisconsin-Madison Madison, WI, 2Department of Food Science, University of Wisconsin-Madison Madison, WI, 3Center for Dairy Research, University of Wisconsin-Madison Madison, WI.

Utilizing Greek yogurt acid whey (GAW) in an environmentally and economically sustainable process is highly desirable. This study uses a novel, catalytic approach to convert GAW into 3 different products: 1) whey protein, 2) milk minerals, and 3) glucose-galactose syrup. The first step in our process involves ultrafiltration (UF) of the GAW to produce a protein and fat-rich retentate. The UF permeate undergoes nanofiltration (NF) in which organic acids, monovalent ions, and some galactose leave as permeate, which can be further utilized as a food ingredient. The NF permeate is heated and brought to pH 7 to precipitate calcium phosphate. The calcium phosphate is harvested as the high-value product milk minerals using a recently developed method involving a combination of hydrocyclone, microfiltration (MF), and spray dryer processing which allows for control of the particle size. To prepare for the catalytic hydrolysis reaction, the MF permeate undergoes acidification to pH 1.3 using cation-exchange resins that remove 70% of the nitrogen species which cause catalyst and product degradation. We have demonstrated that a hydrolysis reaction using a sulfuric acid catalyst is orders of magnitude faster than enzymatic processes and achieves a glucose and galactose yield of 83%. Finally, anion exchange resin adsorption, evaporation and activated carbon filtration produce a purified glucose-galactose syrup which can be used as a sweetener. We have demonstrated this technology at the pilot scale (>100 gallons/h) at the pilot plant operated by the Center for Dairy Research at Babcock Hall in UW-Madison. An economic analysis of this process shows that Greek yogurt producers could have an additional revenue of over $3 million per year by applying this technology.

Keywords: waste reduction, catalysis, filtration.

Biography: I am a graduate student in Chemical and Biological Engineering at the University of Wisconsin-Madison with an expected graduation date of August, 2021. My research involving the development of products such as milk minerals and a sweetener syrup from dairy waste has led to a patent application and two publications. My engineering background combined with my knowledge of dairy processes allows me to develop novel solutions to problems in the dairy industry.