§179.39 Ultraviolet radiation for the processing and treatment of food
Ultraviolet radiation for the processing and treatment of food may be safely used under the following conditions:
（a） The radiation sources consist of low pressure mercury lamps emitting 90 percent of the emission at a wavelength of 253.7 nanometers （2,537 Angstroms）.
（b） The ultraviolet radiation is used or intended for use as follows:
| Irradiated food | Limitations | Use |
| Food and food products | Without ozone production: high fat-content food irradiated in vacuum or in an inert atmosphere; intensity of radiation, 1 W (of 2,537 A. radiation) per 5 to 10 ft.2 | Surface microorganism control. |
| Potable water | Without ozone production; coefficient of absorption, 0.19 per cm or less; flow rate, 100 gal/h per watt of 2,537 A. radiation; water depth, 1 cm or less; lamp-operating temperature, 36 to 46 °C. | Sterilization of water used in food production. |
| Juice products | Turbulent flow through tubes with a minimum Reynolds number of 2,200. | Reduction of human pathogens and other microorganisms. |