SELECTIVE DEPLETION OF RIBOFLAVINE FROM BEER USING MEMBRANES INCORPORATING IMPRINTED POLYMER PARTICLES

The synthesis and characterization of imprinted polymer composite membranes and use of the membranes for depleting riboflavine from beer are hereby reported. The membranes were prepared by phase inversion of a suspension of imprinted polymer particles, which had previously been shown to exhibit selective recognition of vitamin B2 in aqueous media in a solution of poly-methylmethacrylate and polyethylenglycol in acetone. Membranes with different loads of imprinted particles were prepared and characterized by scanning electron microscopy, Fourier-transform infrared chemical imaging and permeability measurements. Subsequently they were tested in both static and dynamic partitioning experiments concerning their ability to bind riboflavine versus other competing solutes such as lumichrome and uridine. The membranes exhibited a pronounced selectivity for riboflavine and were capable of partially depleting nearly 80% of the vitamin from beer. Meanwhile, a membrane prepared identically using nonimprinted particles resulted in a maximum removal of nearly 50%, however, with low selectivity. PRACTICAL APPLICATIONS Membranes incorporating molecularly imprinted polymer particles is a new tool for food processing allowing the traceless removal of preselected substances, e.g., flavors, spoilage agents or impurities. As suggested by the results presented in this contribution, such membranes could potentially find use in the brewing industry for selective depletion of riboflavine thus leading to enhanced beer stability.