Pulsed Ultraviolet Light Decontamination of Meat Conveyor Surfaces

Contact with continuous belt conveyors during processing results in opportunities for pathogenic and spoilage microorganisms to contaminate meat products. The objective of this project is to investigate the germicidal response on the surface of food-grade conveyor belt materials treated with pulsed ultraviolet (PUV) light. Four conveyor belt types including: a stainless-steel chain-link belt, a polytetrafluoroethylene (PTFE)-coated fabric belt, a solid pliable polymer belt, and a rigid-linked polymer belt, were evaluated for the inactivation of Escherichia coli K12-NSR strain and lactic acid bacteria (LAB). Prior to bacterial inoculation, samples were classified as soiled or unsoiled, based on the presence or absence of pork intramuscular fluid on the surfaces of the conveyor samples. Using a variable speed conveyor, equipped with a Xenon flashlamp positioned 10-cm above the surface, each belt sample was exposed to PUV light at three fixed conveyor speeds: 3.05, 15.24, and 30.48 cm/sec, resulting in a total energy exposure of 3.31, 0.66 and 0.33 J/cm2, respectively. For samples inoculated with E. coli K12-NSR, the surface condition (soiled or unsoiled) by treatment interaction was significant for microbial inactivation on the surface of the rigid polymer linked belt (P < 0.05). For samples inoculated with the LAB cocktail, the same interaction was significant for the PTFE-coated fabric belt and the solid pliable polymer belt (P < 0.05). Microbial reduction ranged from 0.74 to 5.04 log10 CFU/cm2 for E. coli K12-NSR and 0.63 to 4.61 Log10 CFU/cm2 for LAB for the evaluated treatment parameters. The results of this project demonstrate that PUV light is an effective means of decontamination for conveyor belts during food processing.

Optimum Lasing Cavity for Erbium Doped Zinc Tellurite Glass Rods Embedded with Ag Nanoparticles

A laser cavity was constructed for excitation of erbium doped zinc tellurite glass rods embedded with various concentration of Ag nanoparticles. Central to the system is a Xenon flashlamp for optical pumping, and mirrors to amplify the light waves. The amorphousity of the glass rod was studied by X-ray diffraction and the existence of silver nanoparticles inside the glass was confirmed by high resolution transmission electron microscopy analysis. The photoluminescence properties and differential thermal analysis curve of the samples confirmed the compatibility of the rods as gain medium. The rods were successfully fabricated and incorporated inside the laser cavity. The output of the laser with erbium doped zinc tellurite glass rods embedded with Ag nanoparticles was characterized via spectrum analyser and was found that the spectrum dominated at line 473 nm and 506 nm. The beam profiler was utilized to detect and display the laser beam in 3D.