New oxidation destructive analysis (NODA)

Abstract

Beer pigments compose of caramels, melanoidins and polyphenols pigments, which can be prepared by heating or boiling of mild colored or colorless precursors, such as sugar or (-)-epicatechin. The natural pigments behave as natural pH and redox indicators. During preparation of caramels by sugar heating at 175 °C in oven, various sugars came into slight yellow (maltose), brown (glucose, mannose, ribose, xylose), or dark brown (arabinose, fructose) products. At heating, reductones were formed prior to caramel pigments. Redox indicators were added to beer and the absorbances (at 666 nm for methylene blue, 520 nm for methyl red and 610 nm for indigocarmine) were recorded before and after illumination with visible light (5 min) under aerobic and anaerobic condition. Natural or synthetic indicators can change their color reversibly or irreversibly. Reducing compounds can initialize oxygen free radical formation as well as their scavenging. 1,2-diaminobenzene addition supported the oxygen consumption in beer