SUBACUTE TOXICITY OF MILDLY OXIDIZED INSTANT NOODLES IN MICE

Abstract

A 28-day sub-acute toxicity test using moderately oxidized fats and oils (peroxide value [PV] 85.0–334.7 mEq oxygen/kg) extracted from deteriorated instant noodles was performed in mice to evaluate general toxicity. Toxicity was evaluated by general behavior, survival rate, clinical hematology, clinical chemistry, organ weights, changes in body weight and histopathologic examination. None of the mice died due to the toxicity of the oxidized fats and oils. Fats and oils oxidized to at least 300 mEq oxygen/kg attenuated weight gain compared with the control mice, but mice fed fats and oils oxidized to less than 150 mEq oxygen/kg gained weight similar to the control mice. Thus, fats and oils oxidized to approximately 300 mEq oxygen/kg induce general toxicity, but are not lethal. In contrast, liver weight and blood cholesterol levels tended to increase in all test oil groups. Thus, body function is affected by even mildly oxidized fats and oils (100 mEq oxygen/kg); hence, ingestion of degraded foods should be avoided. PRACTICAL APPLICATIONS Japan had a food poisoning epidemic caused by the degradation of fats and oils in instant noodles about 40 years ago. The peroxide value of the oxidized fats and oils in the degraded noodles ranged from 100 to 1,000 mEq oxygen/kg. According to the detailed investigation of the degraded noodles, the Ministry of Health and Welfare, currently the Ministry of Health, Labor, and Welfare in Japan, set the standards in the Food Sanitation Law to protect against food poisoning and to control the quality of instant noodles. Recently, there was a movement to set a standard for instant noodles in the Codex Alimentarius Commission. Probably, food standards for other kinds of lipid-containing foods might be prepared in the Codex Alimentarius Commission in the near future. General toxicity tests have so far focused on highly oxidized fats and oils (>400 mEq oxygen/kg) and have not considered the moderately oxidized products (<400 mEq oxygen/kg). Therefore, general toxicity testing on the moderately oxidized fats and oils was carried out, and the results can provide new information when new food standards containing fats and oils are prepared.