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Functionalized mesh materials for Listeria mitigation in milk and milk­ derived products processed in dairy plants


Obj 1. Synthesize functionalized feed spacer mesh material through a multi-step process including initiator generation, synthesis of modified polystyrene, and reaction to form quaternary amines. Obj 2. Synthesize a second block by adding selective adsorptive sites to the functionalized feed spacer mesh Obj 3. Characterize the functionalized material Obj 4. Demonstrate stability in conditions relevant to membrane clean-in-place (CIP) methods, hot water, and autoclave conditions. Obj 5. Demonstrate anti-microbial activity to LM Obj 6. Demonstrate sterilizability with hot water and steam Obj 7. Demonstrate enhanced adsorption of LM Abstract: The proposed research will develop a new technology for Listeria control in dairy. Raw milk is pasteurized prior to further processing because it may contain Listeria and other microbial contamination. The pasteurization process will only destroy Listeria if it is improperly applied. Listeria that remains or is reintroduced by contamination can be adsorbed or destroyed during downstream processing of milk during membrane filtration by using a functionalized feed spacer material in a spiral membrane element. The feed spacer is a mesh material and the surface will be modified to promote Listeria adsorption. The coating chemistry is based on the receptor chemistry of cells lining the intestine which are strongly bound by Listeria surface protein. Anti-microbial agents immobilized on the surface can then kill the Listeria. Sterilizing the membrane element with hot water or steam will also kill adsorbed Listeria. The functionalized mesh can be applied broadly in dairy plants for a range of milk and milk-based streams, including brine streams. The feed spacer mesh is an integral part of all spiral wound membrane elements, and can be applied with any membrane, such as ultrafiltration of raw milk. The mesh can also be applied in the absence of a membrane in recirculating systems to inhibit Listeria growth. The starting material is temperature resistant polypropylene and grafts are chemically bound to the surface. The modified material can be applied in temperature-stable sanitary elements, and may be steam sterilizable after Listeria adsorption and material saturation.

Stephen MC Ritchie, Ryan Summers
The University of Alabama
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