Changes in Hardness and Cell Wall Polysaccharides in Koumezuke (Salted Small Mume Fruit)

Abstract

The relation between cell wall polysaccharide constituents and hardness of Koumezuke (salted small mume fruit) were investigated. 1) The cell wall polysaccharides of small mume fruit consisted of 35-45% pectin, 30-37% hemicellulose and 25-28% cellulose. An increase of pectin content, and a decrease of hemicellulose II (soluble in 17.5% NaOH) and cellulose content were observed during maturation. 2) When mume fruit was salted with Ca (OH)₂, pectin and hemicellulose I (soluble in 5% NaOH) in the cell wall showed decrease, but cellulose and hemicellulose II showed an increase. And the increase of pectin was observed in the fruit salted without Ca (OH)₂. 3) In the cell wall pectin of Koumezuke, a decrease of the methoxyl group and increases of ash and Ca content were observed during salting. These increases were remarkably observed in the Koumezuke which maintained fruit hardness by salting with Ca (OH)₂. 4) Three main pectin fractions in fresh small mume fruit and Koumezuke were eluted by 0.10-NaOH, 0.30 M and 0.20 M-phosphate buffer on DE AE-cellulose chromatogram.