Changes in Hardness and Cell Wall Polysaccharides of Small Size Ume 'Koshu Koume' Fruit during Maturation and Its Brining

Abstract

The changes in cell wall polysaccharides constituents in relation to hardness in small size ume fruit and Koumezuke (brined small size ume fruit) were investigated. While small size ume fruit softened in texture during maturation, the cell wall polysaccharides contents reduced to half from 2937mg/100g to 1460mg/100g. At the same time, the content of the pectin fraction was increased 44.3-0.1%, and that of hemicellulose II and cellulose fractions were decreased, 17.4-11.9% and25.9-21.9%, respectively. Koumezuke, brined in the solution calcium hydroxide was added and had a hard texture, had a constantly larger content of the cell wall polysaccharides than the fruit brined only with NaCl. The decrease was observed in pectin and hemicellulose I fractions components, on the other hand, hemicellulose II and cellulose fractions components were increased. Furthermore, ash and Ca bound to crude cell wall were remarkably larger in Koumezuke, and in the pectin fraction of Koumezuke, AGA content was small and neutral sugar content was large. From these results, the maintenance of hardness of ume were only performed in case of brining with calcium hydroxide. This phenomena was supposed to be caused by the fortified cell wall with calcium hydroxide, and it was caused by the increasing of hemicellulose II and cellulose fractions tightly bound to the cell wall which was formed through an obstruction of resolve of HSP and its combining with other cell wall constituents.