Measuring Thiamine Disulfide Reducing Substances in Cheddar Cheese

Abstract

The content of thiamine-disulfide (TDS) reducing materials of commercial Cheddar cheese samples ranged from 2.3 to 30.2 mg cysteine HC1 equiv./100 g. The average TDS was 15.9. Generally, one- to 12-mo.-old cheese contained higher concentrations than 16- to 18-mo.-old cheese. The method modification involved sample preparation, which included the maceration of 1 g of freshly drawn cheese in 5 ml of 2% sodium-citrate, 1 ml of TDS substrate and 4 drops of isobutyl alcohol. The reaction was stopped after 2 hr. by addition of 10% trichloroacetic-acid (TCA) to a final volume of 10 ml. Active sulfhydryl groups exposed during the ripening process constitute the major portion of TDS reducing materials. The contributions of H2S were less than 2% of the TDS.