STUDIES ON INFLUENCE OF RAYS UPON FILM PACKING-I

During the past ten years, varieties of plastic film have been developed; many of them are now used for food packing. It is generally accepted that various rays cause discoloration, oxidation and rottening of food components. However, little has been studied on such influences especially of ultraviolet ray through transparent film materials. The authors carried out an investigation on influences of rays on oil materials absorbed on sponge, which were packed in film materials having various permeability against rays and oxygen, by determining oxidation of each packed material. It was found that the ultraviolet ray from a fade meter caused the strongest oxidation of the oil materials; sun beams caused a considerable oxidation; while no oxidation resulted from radiation by the germicidal ray from a lamp. The oil materials packed without sponge or those absorbed onto sponge and vacuum-packed both to minimize the contact with oxygen underwent oxidation larger by oxygen permeating through the film rather than by ultraviolet rays. On the other hand, the oil materials absorbed onto sponge and packed in different films to allow to contact with oxygen were oxidized most strongly by the ray of 3, 850Å and less strongly with sun beams. The ray of 2, 540Å, caused no or little oxidation of the materials.