Ca-binding compounds in cell wall of peanut shell

Abstract

Ca compounds combined with the cell wall of the peanut shell were investigated by molecular sieve chromatography. The supernatant centrifuged after digestion of the cell wall by cellulase and the ligneous substances extracted with dimethylsulfoxide were loaded on a Sephadex gel column, respectively. In the former a part of Ca was eluted with the phenolic acids and carbohydrates, while in the latter Ca was eluted with lignin and the carbohydrates in the void volume. The major components of the phenolic acids were p-coumaric, caffeic, and ferulic acids. In the normal shell, the molar ratio of Ca to caffeic acid of the phenol-carbohydrate complexes was approximately 1, while in the Ca deficient shell the ratio decreased to about 0.7, mainly due to an increase in the caffeic acid moiety of the complexes. In the cell wall of the peanut shell, the presence of a Ca chelate bridge more stable than ionic bonds was suggested.

Key Words:

• calcium
• phenol-carbohydrate complex
• caffeic acid
• cell wall of peanut shell