Abstract: The microbial life and color life of fresh meat products are extended by placing fresh meat in a tray, sealing the fresh meat in the tray in an atmosphere that excludes oxygen and contains carbon monoxide, and applying ionizing radiation to the tray containing the fresh meat. The color life of the fresh meat in the tray may be controlled (such as to be equal to or less than the microbial life) by employing a permeable element and an impermeable element to seal the fresh meat in the tray. The impermeable element is removed at a time after ionizing radiation has been applied, so that the atmosphere that excludes oxygen and contains carbon monoxide is exchanged for ambient atmosphere, resulting in predictable limiting of color life of the fresh meat.

Abstract: Articles are irradiated by positioning an article to be irradiated in a processing area, controlling an atmosphere in the processing area to exclude oxygen, and applying radiation to the article in the processing area. In one embodiment, the article is positioned in the processing area by conveying the article on a top surface of a product conveyor in the processing area. One exemplary article for irradiation is a tray of fresh ground meat. The tray of fresh ground meat that is positioned in the processing area for irradiation may itself exclude oxygen as well.