Date of Award:

5-1991

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Science

Committee Chair(s)

Arthur W. Mahoney

Committee

Arthur W. Mahoney

Committee

Deloy G. Hendricks

Committee

James Gessaman

Abstract

The validity of the Homsey method for heme iron, modified Schricker and sodium pyrophosphate extraction methods for nonheme iron and atomic absorption spectrophotometry (AAS) and ferrozine methods for total iron were determined using spikes of hemoglobin, ground beef baked to different degrees of doneness, proportional beef liver:catfish mixtures and National Institute of Science and Technology reference materials.

The mean spike recoveries of 0.01g and 0.02g Hb in raw beef and raw chicken samples were 96.7% of the heme iron for the Homsey method, 97.9% of the total iron for the ferrozine method, and 85.7% of the total iron for the AAS technique.

In ground beef patties baked rare, medium and well-done, the nonheme iron values increased with doneness as determined by both methods and there were no significant differences between the mean values obtained by the two methods. The sum of heme and nonheme iron equalled total iron in beef patties baked rare and medium. The Homsey method seemed to overestimate the heme iron content in well-done beef possibly due to browning. The total iron content remained constant. However, total iron determined by the ferrozine method was higher (p < .05) than that analyzed by the AAS method.

Heme and nonheme iron values were plotted against beef liver concentrations in the beef liver:catfish mixtures, and the correlation coefficients obtained were 0.994 for the Homsey method, 0.991 for the modified Schricker method, and 0.995 for the sodium pyrophosphate method. Heme iron plus nonheme iron equalled total iron for all the mixtures. Student's t test revealed no significant difference between ferrozine total iron values and NIST-certified concentrations, but the AAS total iron values were significantly (p < .05) lower than the NIST-certified values.

The Hornsey method was validated for all samples except well-done beef. The two nonheme iron methods were reliable and accurate. While the fenozine technique was consistent, reliable and accurate, the AAS method was able to detect, on an average, only 80-85% of the total iron present. There was no interference of the sample mineral matrix with the detection ability of the AAS method.

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