APPLICATIONS AND SOURCES OF ULTRAVIOLET 85 



of those methods, there must be a complete removal by centrifugiiig or 

 filtration of all clumps down to an empirically determined and specified 

 size. A machine or process should produce a specified degree of sterility 

 in test runs of plasma contaminated with a test organism of an ultra- 

 violet-exposure tolerance comparable with that of the hepatitis virus. 

 Sarcina Infca, whose packet growth habit may simulate the minute 

 clumps remaining in plasma after clarification, is suggested. 



In operation there should be a continuous record of plasma flow and 

 ultraviolet intensity, similar to the controls used in continuous methods of 

 milk pasteurization. A cadmium photocell (Figs. 2-1 and 5b), described 

 by Taylor and Haynes (1947), and a recording microammeter are suitable 

 for the ultraviolet control. The rate of flow may be controlled by a pump 

 with variable-speed drive. Rapidly operating relays and electric valves 

 should stop or divert the delivery of plasma from an intermediate storage 

 reservoir of a capacity much greater than that of the irradiating device. 



SYRUP, FRUIT-JUICE, AND WINE STORAGE 



The sugar content of sugar and fruit syrups is usually such as to 

 prevent fermentation even though a mold scum ma}^ form on exposed sur- 

 faces. Whenever there is condensation of moisture on the sides and tops 

 of syrup-storage tanks, it may dilute the surface layer of the stored syrup 

 enough to permit destructive and otherwise very objectionable fermen- 

 tation in addition to the usual mold formation. Germicidal tubes are 

 being used to prevent such fermentation and mold on the surfaces of 

 tank-stored sugar and fruit-juice syrups used for soft drinks and con- 

 fectionery. Continuous irradiation with an intensity of at least 5 ultra- 

 violet mw/sq ft is required. 



MEAT STORAGE 



The most extensive single industrial use of germicidal lamps is to 

 reduce the growth of bacteria and molds on the surface of meat and on 

 shelves, walls, and floors of retail-meat-storage refrigerators operated 

 at 35°-45°F. There is little need for such provisions in cold-storage 

 rooms operated below zero, nor has there been any such need in the larger 

 meat-processing factories where exact control of temperature, humidity, 

 and air movement produces similar results. Proper use of the ultraviolet 

 does not take the place of established periodic sanitary maintenance but 

 does supplement it by a continuous suppression of spoilage and odors. 

 The ultraviolet intensities required are of the order of only the 5 mwsci ft 

 effective for mold suppression in other applications. 



Ultraviolet is effectively used to suppress surface slime molds on meat 

 stored for 3 days at a temperature of about 60°F for rapid aging or 

 tenderization. Contrary to the impression of some, the ultraviolet has 

 no direct effect on the enzymatic tenderizing. 



