Use of Novel Surface Modification Techniques to Reduce Biofilms on Plate Heat Exchanger Plates

Modifying the surface properties of plate heat exchangers (PHE) will reduce the surface energy of plates, the rate of absorption of foulants and microbial attachment, and reduce the risk for spores and thermoduric bacteria in finished products. Surface modifications and coatings for stainless steel (SS) coupons and plates will be selected based on high clean-in-place (CIP) chemical resistance, high temperature resistance, high thermal conductivity, oleophobicity, and low surface energy. The selected coatings will be applied to the SS coupons and plates using spin coating or dip coating methods. Raw milk will be pasteurized with the original plates and the modified surfaces. The modified surfaces will be compared with the original surfaces in terms of biofilm/deposited layer thickness. </P>Researchers will determine if CIP will remove biofilms from the surfaces of these plates. Initial screening of these surfaces will be done by developing single and mixed species biofilms on SS coupons of the modified surfaces. After the initial screening, a lab scale PHE will be used to recirculate milk inoculated with specific thermoduric isolates for 20 h. Samples will be drawn at regular intervals to evaluate the growth of thermoduric thermophiles and their spores. After each run, a study will be conducted to screen CIP protocols for their efficacy in cleaning these thermoduric biofilms. The most effective surface treatment selected from the lab scale experiments will then be evaluated on an industrial scale PHE. Industrial plates will also be evaluated in terms of effectiveness in reducing the biofilm formation.