Studies on Sulfur Stain of Internal Wall of Cans

Part I. Corrosion factors in asparagus

Abstract

The existence of the unknown substance (s) was suggested, which was entirely different from so-called "corrosion factors" such as nitrates, anthocyan pigments, cysteine and cystine and presumably plays the main role in the corrosion reaction in canned asparagus.
White asparagus was extracted with 75% ethanol and the fractions with ion exchange resins and ethereal extraction were examined as to the corrosion activities.
Both the sulfur-staining and corroding activities were found in the effluent from Dowex 50W×8 (H⁺ form). Further fractions with Amberlite IR-45 (OH^- form) treatment showed considerable activities of sulfur stain and corrosion.
By paper chromatograms of the hydrolyzates of the fractions, citric and tartaric acids were detected, which were not detected on paper even after extraction of the unhydrolyzed fraction with ether for 120 hours. The hydrolyzates and one of the ethereal extracts contained significant amount of glutamic acid.
It is assumed that at least one of the sulfur-staining and corroding factors in the fresh plants is the loose conjugate of glutamic acid and the organic acids. Results obtained from the fractionation studies also strongly indicates that sulfur containing carbohydrates and organic acids are involved in the sulfur-staining reaction of the internal wall of canned asparagus.