Date of Award

1986

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Raw, broiled and fried beef liver samples were stored at -20(DEGREES)C in either vacuum or air-saturated packages. At periods of 30, 60 and 90 days the folates were extracted and analyzed by reverse phase high performance liquid chromatography (HPLC). Tetrahydrofolic acid (THF), dihydrofolic acid (DHF), 5-CH(,3)-THF, 5-CHO-THF and pteroylglutamic acid (PGA) were identified and quantitated. Two major folate oxidation products, pterin-6-carboxylic acid (pt-6-COOH) and p-aminobenzoylglutamic acid (p-ABG) were also detected. The total folate content of beef liver was higher than previously reported. PGA was not found in any of the samples but a large peak corresponding to the retention time of DHF was observed. The order of stability of the folates towards cooking was: DHF < 5-CH(,3)-THF < 5-CHO-THF < THF. The stability of THF may have been a function of the reduction of DHF. Levels of 5-CH(,3)-THF, THF and DHF decreased during frozen storage while those of 5-CHO-THF generally increased. These trends were not always linear over time. Folate interconversions and deconjugation of pteroylpolyglutamates during storage was suspected. The HPLC quantitation of total folates consistently resulted in higher values than that by the Lactobacillus casei microbiological assays.

Pages

173

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