THE RELATIONSHIP BETWEEN THE CONSTITUENTS OF CELL-WALL POLYSACCHARIDES AND HARDNESS OF BRINED UME FRUIT

The cell wall polysaccharides in fresh and brined ume fruits were frac tionated, and the relation between their chemical composition and hard ness was investigated. The main components of each cell wall polysacch aride were as follows:pectin fraction (PS) containing galacturonic aci d (AGA), hemicellulose I fraction (HC-I) containing neutral sugars and proteins, hemicellulose II (HC-II) containing neutral sugars and ash, and cellulose fraction (CL) containing neutral sugars. In the Control (ume fruit brined with NaCl solution), there was a decrease in HC-I a nd CL in the cell wall, and an increase in PS, as well as a softening of texture. On the other hand, a decrease of PS and an increase of CL were observed in the Ca-added group (ume fruit brined with NaCl soluti on and Ca hydroxide), which maintained a hard texture. A decrease in t he methoxyl group and an increase in ash and Ca content were observed in PS of the Ca-added group. A decrease of neutral sugar (especially, glucose composition) and an increase in ash, Ca and AGA content were o bserved in CL. CL contained AGA and neutral sugars such as arabinose a nd galactose, which were thought to be firmly bound to cellulose micro fibrils. Therefore, it was assumed that the hardness in Umezuke may re flect a difference in the mechanism of bonding between CL existing in the secondary cell wall and other matrix polysaccharides.