Prevention of microbial and biofouling attachments in food processing applications using nanoengineered surfaces

Abstract

L. monocytogenes (1.9×108 CFU/mL) was used for bacterial adhesion testing of nanoengineered stainless steel surface, which may be more demanding for hygienic food processing equipment. The NS stainless steel surface was achieved by electropolishing the steel in a mixture of sulfuric and phosphoric acid. For NR stainless steel fabrication, the bare substrates were anodized in a mixture of perchloric acid and ethylene glycol to create two surfaces with two different in nanopore diameters ( 50 nm and 80 nm), so-called NP50 and NP80, respectively. Thereafter, the NS, NR50, and NR80 stainless steels were exposed to the L. monocytogenes solution in a stagnant environment for four hours. The enumerated average cell counts were 5×103, 5.0×101, and 2.8×101 CFU/cm2 for NS, NR50, and NR80, respectively. The results suggested that regardless of the substratum materials, nanoporous surface finishes could significantly inhibit the adhesion and attachment of L. monocytogenes. However, the statistical analysis indicated that the numbers of cells adhering to the 50 nm and the 80 nm nanoporous surfaces were not significantly different. The finding could be because besides the pore diameter, other surface parameters such as peak heights (or pillared magnitudes) and interpore distances might also play an important role on anti-adhesion of L. monocytogenes.