Amino Acid Composition of Protein Bound to Cell Wall Polysaccharide of Fresh and Salted Mume Fruit

Abstract

Cell wall polysaccharides from fresh and salted mume were fractionated, and the quality of glycoprotein bound to the polysaccharide and amino acid composition were investigated. The content of glycoprotein in hemicellulose- I fraction was the highest and that in pectic substances, cellulose and hemicellulose- II fractions became successively lower in this order.
For each fraction, the composition ratio of each amino acid to the total amino acids was different, however, hydroxyproline, glutamic acid and aspartic acid were common to all the fractions. A difference in amino acid composition was found between the Control (brined with NaCl solution) and the Ca-added group (brined with NaCl solution and calcium hydroxide), and especially the behavior of hydroxyproline was quite different. The hydroxyproline of the Control group increased in the pectic substances fraction while it decreased in the hemicellulose-I fraction. On the contrary, hydroxyproline content of the Ca-added group, which presented quite a hard texture, increased in hemicellulose- II and cellulose fractions.
From these results, it was suggested that the increase of the hydroxyproline content in hemicellulose- II and cellulose fractions, whose affinity to the cell wall is stronger than pectin and hemicellulose- I fractions, contributes to the strength of the cell wall structure, in the case where the hardness of mume texture is maintained by the addition of calcium hydroxide.