SummaryAn improved distillation method is described for the quantitative determination of malonaldehyde in foods containing oxidized fats. The procedure is compared with other methods in current use for the determination of malonaldehyde. A high correlation of TBA numbers with rancid odor in cooked meats was established.

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Female athymic nude mice were implanted subcutaneously with human breast carcinoma MDA-MB231. Seven to ten days later, the mice were divided into groups and fed a purified diet containing the following types of fat (% of diet): (i) 20% corn oil (CO); (ii) 15% CO:5% fish (menhaden) oil (FO); (iii) 10% CO:10% FO; (iv) 5% CO:15% FO; (v) 1% CO:19% FO; and (vi) 1% CO:19% FO plus antioxidants (alpha-tocopherol acetate, 2000 IU/kg diet and tertiary butyl-hydroquinone, 2% of total fat). The linoleic acid levels (% of diet) of the groups were 12.0, 9.1, 6.2, 3.3, 0.9 and 0.9%, respectively. After 6-8 wk, the carcinomas were assessed for tumor volume (cm3) and assayed for thiobarbituric acid reactive substances (TBARS). Human breast carcinoma growth was suppressed in mice consuming FO diets without antioxidants as compared to mice fed CO; the greater the amount of dietary FO fed, the greater the carcinoma growth suppression (P < 0.05). The addition of antioxidants to the FO diet significantly (P < 0.05) reversed the FO-induced carcinoma growth suppression. Concentrations of TBARS in the human breast carcinomas were increased in all the FO (without antioxidants) fed mice, compared to mice fed CO; the level of increase in TBARS was directly related to the increase in the level of FO fed (P < 0.05). The addition of antioxidants to the FO diet significantly (P < 0.05) reduced the concentration of TBARS in the breast carcinomas.(ABSTRACT TRUNCATED AT 250 WORDS)

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Photooxidation of olive oil, bleached to remove most non-triglyceride components, was studied to elucidate the role of added chlorophyll a, pheophytin a and b, c~-and 3-carotene, d~-tocopherol and nickel dibutyldithiocarbamate.Chlorophyll functioned as a photosensitizer resulting in rapid oxidation of the oil and the added components and loss of color. a-and 3-carotene acted essentially equally as singlet oxygen quenchers. c~-tocopherol had little apparent effect on the oxidation rate. Carotenes and tocopherols apparently were destroyed more rapidly when chlorophyll was present. The ratio of peroxide value to conjugated dienoic acids formed developed greater values when chlorophyll was present, thus suggesting a singlet oxygen effect in the system. Pheophytin also proved m be an oxidation promoter.