UV Disinfection of Juices

The Federal Register (April 24, 1 998) reported several cases of illness resulting from consumption of various types of juices, mostly unpasteurized apple cider. UV light disinfection is a nonthermal process which involves the exposure of pathogenic microorganisms light radiation, between 200-400 nm. UV light inactivates microorganisms by attacking their DNA, which renders them incapable of reproduction. A big obstacle in the application of UV light processing in fruit juices is the low transmittance at the UV range. For UV processing to be effective,the required dosage at specified wavelength must be delivered. A major focus of this project is to develop protocols to validate the UV dose for destruction of pathogens. Effectiveness of UV light against target pathogens and surrogates will be evaluated using a continuous type UV reactor. Chemical actinometry will be used to measure radiation dose in juices subjected to UV radiation. Natural components of juice will be monitored for suitability to use as radiation markers. Degradative photochemical reactions, such as browning and vitamin deterioration, will be studied in juices subjected to UV processing. Investigators also plan to submit a proposal for external funding at a later date. The most effective wavelength for disinfection is about 254 nm and it is usually produced using low pressure mercury lamps. However, the use of broader band light sources, i.e. medium pressure mercury lamps, which produces UV light at the range of 200-400 nm has been found effective against microorganisms that require high dosage for inactivation, e.g. cryptosporidium.