Effect of Atmospheric Oxidation on Bioavailability of Meat Iron and Liver Weights in Rats

Iron bioavailability of diets containing oxidized turkey and oxidized beef meat was investigated in two experiments. In both studies male, weanling rats were made anemic by consumption of a low iron diet and bleeding. The experimental diets were prepared so that meat was the only source of iron. Hemoglobin regeneration served as the basis for measuring iron utilization. In experiment 1, lyophilized, uncooked turkey meat was allowed to oxidize at 20-22°C for 0, 48, 96, 144, 216, or 264 hours and then fed to the rats. The length of oxidation time of the turkey meat did not significantly affect the growth of the rats or the bioavailability of the meat iron. In experiment 2, lyophilized, uncooked beef was allowed to oxidize at 20-22°C for 14 days. Anemic rats were fed diets composed of basal, basal + iron, basal + iron + formaldehyde, 100% fresh beef, 75% fresh 25% oxidized beef, 50% fresh-50% oxidized beef, 25% fresh-75% oxidized, 100% oxidized beef and 100% fresh beef + formaldehyde. Rats fed severely oxidized beef diets had decreased body weight, enlarged livers and depressed hematinic responses. Formaldehyde did not significantly affect iron utilization in rats fed basal diets, but depressed liver iron storage in rats fed fresh beef. A third experiment to further compare the chemical properties of uncooked, lyophilized hand deboned and mechanically deboned beef and turkey meat was performed. Analysis by the Thiobarbituric Acid Method, Formaldehyde Value, and Iodine Number indicated increased sophistication of testing methods for lyophilized meats needs to be developed. Although the Thiobarbituric Acid Method was successfully used in Experiment 1, unreliable results were obtained using this method in Experiment 3. It is assumed that this variability in results is due to using the Thiobarbituric Acid Method with a dry system. The problems encountered with the Formaldehyde Value included contamination of the water supply with aldehydes and unreliable reagent. The Iodine Number was unreliable used on meat samples. Possibly the fat could be extracted from the meat under cool nitrogen to prevent further oxidation of the fat. Then the iodine number could be determined on the extracted fat