Pulsed UV (PUV) power techniques were studied as a nonthermal, residue-free alternative to contact pesticides and to evaluate the surface disinfection of fresh fruits using this type of extremely rapid, high-peak power UV beams. Coherent 248-nm beams from excimer lasers were used to simulate a variety of pulsed light sources now commercially available. Surface disinfection on a series of fresh fruits (i.e., apples, kiwi, lemon, nectarines, oranges, peaches, pears, raspberries, and grapes), representing economically important commodities, were studied and evaluated. Plant (fungal) pathogens were rapidly (<10 s), efficiently (>5 log), and reproducibly killed on fruit surfaces. However, in naturally infected or inoculated (sprayed) fruits, a fraction of the inoculum may penetrate into the epidermis or locate in injured tissue in crevices or in surface irregularities. Under these conditions, only partial disinfection was obtained due to UV shielding (shadowing) effects, which prevent the highly directional, coherent PUV beam from reaching its target. For maximum disinfection efficiency, coherent PUV sources must be combined with dispersing reflectors, and fruits must be handled to ensure uniform exposure to multidirectional incident beams. New, existing, noncoherent, broadband, pulsed light beams (high in UV emission) from arc lamps appear to provide adequate PUV light sources capable of meeting the conditions for commercial applications in slight-modified conveyorized operations. Therefore, PUV techniques may provide effective, commercial-scale, reliable, and viable residue-free alternatives to chemical (contact) pesticides.

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Inactivation of Toxoplasma gondii oocysts occurred with exposure to pulsed and continuous UV radiation, as evidenced by mouse bioassay. Even at doses of ≥500 mJ/cm2, some oocysts retained their viability.

Radiofrequency (RF) heating was investigated as an alternative to cooking, drying or chemical disinfection for the preservation of fishmeal and shown to be a highly effective process without any detectable effects, particularly on proteins, lipids or in vivo digestibility. The uniform and deep penetration of RF waves resulted in rapid and homogeneous heating allowing ∼4 times lower thermal loads to be used for >5 log 10 (>99.999%) reduction in infection levels for Salmonella spp and for Escherichia coli O157:H7. Simultaneously, the natural flora was reduced by >3 log 10 (>99.9%). The RF process can be operated in the 70-90 • C range and with high energy-use efficiency (∼50%), which compares well with the 10-15% efficiency for conventional surface heating methods. Industry and expert laboratories confirmed these results. RF heating is thus a new alternative thermal process that is particularly appropriate for disinfecting fishmeal or for reprocessing it rapidly and efficiently with full retention of its natural attributes.

Radiofrequency (RF) power was investigated as a new, physical (nonchemical), thermal process to disinfect wastewater from dairy and animal facilities. Samples (n = 38) from 8 dairy, 2 calf, and 3 swine facilities in California were collected over a 3-yr period and characterized for their dielectric properties, chemical composition, and suitability for thermal processing using RF power. To establish efficacy for disinfection, selected samples were inoculated with high levels (10(6) to 10(9) cfu/mL) of bacterial pathogens such as Salmonella sp., Escherichia coli O157:H7, and Mycobacterium avium ssp. paratuberculosis and processed with an RF prototype system. The capabilities of RF power as a method for thermal disinfection of wastewater were demonstrated when bacteria pathogens were completely and rapidly (<1 min) inactivated when temperatures of 60 to 65 degrees C were achieved. Furthermore, RF technology can be used for large-scale, batch or continuous and portable applications, allowing significant improvements in energy-use efficiencies compared with conventional thermal (surface heating) technologies. Therefore, RF power has potential as an alternative to disinfect dairy/animal farm wastewater before recycling.