Optimum Conditions for the Interaction of Food Gums with the Anthrone Reagent

Abstract

SUMMARY Optimum conditions for the reaction of food gums with the anthrone reagent vary from one gum to another. The sulfated, carboxylic acid type and mixed polysaccharides produced colors with absorption maxima at 620 mμ. The uranic acid type of polysaccharides, pectin and sodium alginate (Kelco Gel HV), produced colors exhibiting absorption maxima at 520 mμ. In all cases, color intensity increased with increasing temperature. The heating time necessary for maximum color development at 99°C varied from 4 to 10‐min, depending on the hydrocolloid in question. With pectin and sodium alginate, although color intensity increased with heating time at 99°C, no definite heating time for maximum color development was observed up to 60 min. In most cases, aging led to a rapid decrease in color intensity, except for pectin and sodium alginate, in which cases color intensity increased.

Reaction of Sugar Alcohols with the Anthrone Reagent

“…Methods have ALCOHOL REACTIONS WITH ANTHRONE REAGENT been proposed for the separation of these alcohols (Genest and Chapman, 1962 ;Jones and Wall, 1960;Moore et al, 1960). Since the absorption maximum for the sugars and most other polysaccharides is at 620 mp, interference by small amounts of sugars would be minimal, and becomes even less because extended heating of the sugar-or carbohydrate-anthrone mixture destroys the color (Helbert and Brown, 1955 ;Graham, 1962). Uranic acids and their polymers Brown, 1956, 1957) and alginates (Graham, 1962) will interfere since they produce a red color that absorbs maximally at around 540 mp and this color is intensified by prolonged heating.…”

“…with the anthrone reagent (Graham, 1962) it was noted that several of the sugar alcohols produced color if the mixtures were heated for 30 min or more. Since information is scant on the interaction of the sugar alcohols with the anthrone reagent, a thorough investigation was deemed profitable.…”