Galacto-oligosaccharides (GOS) and oligosaccharides in general have received a lot of attention recently, mainly due to their many beneficial health effects and wide applications as prebiotic food. Enzyme immobilization on cotton cloth activated with tosyl chloride provides many advantages, including high GOS yield, high reactor productivity, improved thermal stability, and good long-term operating life. The porous cotton cloth gives low pressure drop, good mechanical strength, high surface areas for enzyme immobilization, and low mass transfer limitations, and is inexpensive and easy to scale up. The feasibility of using such an enzyme reactor for GOS production from whey lactose will be studied in this project. If successful, the abundant lactose in whey, a byproduct from cheese manufacturing, can be economically converted to a high-value prebiotic product. Depending on the enzyme source and reaction conditions, the GOS yield may vary from below 20% to as high as 67% (w/w). Methods to enhance GOS production and product yield will be evaluated to improve the production economics. Nanofiltration to separate GOS from lactose and monosaccharides also will be studied. A nanofiltration process may be efficiently used to separate the GOS present in the reactor product stream and recycle the unreacted lactose for improved product purity and yield. ANTICIPATED RESULTS & POTENTIAL COMMERCIAL APPLICATIONS OF RESEARCH The proposed process would produce a high-value product (more than $10/lb) that can be used as a health-promoting food ingredient and dietary supplement from the surplus whey permeate and lactose (less than $0.4/lb) currently produced in the dairy industry. The market for GOS is at $200 million per year in Japan alone. The large, potential U.S. and worldwide markets should exceed $1 billion. Thus, a cost-effective enzyme technology to produce GOS from whey lactose should increase the product value and reduce the waste (whey permeate) disposal problem facing the dairy industry.
