Studies on Sulfur Stain of Internal Wall of Cans

Part II. Amino acid composition of tomato fruit and its relation to the corrosion of internal wall of canned tomato fruit

Abstract

The internal wall corrosion of canned asparagus accompanies no sulfur stain, and obviously differs from that of canned orange juice.
Fresh asparagus has been analyzed in our laboratory as to its amino acid composition in relation to the internal wall corrosion of canned asparagus, and it was shown that one of the corrosion factors of canned asparagus is considered to be a compRund of glutamic acid and organic acids.
In order to ascertain the corrosion factors of tomato fruit, investigations were made on its amino acid composition as well as on the relation between the composition and corrosion of internal wall of the canned plant.
Tomato fruit was extracted with 75% ethanol. Glutamic acid was found to be the major component among amino acids. The extracts were fractionated with ion exchange resins and acid fraction "A-2" was partially hydrolyzed for 2 hours at 100°C with 2.4N HCl, and the hydrolyzate was further fractionated with cation exchange resin. The corrosive activity of each fraction was examined.
The corrosion factors of tomato fruit are adsorbed to anion exchange resin (OH^- form), but not to cation exchange resin (H⁺ form). From resin analysis and paper chromatography, it is concluded that the corrosion factors in tomato fruit are acidic substance and one of them is a conjugated compound of glutamic acid and organic acids.