ISOLATION AND CHARACTERIZATION OF CELL-WALL POLYMERS FROM OLIVE PULP (OLEA-EUROPAEA L)

Cell wall material (CWM) was prepared from olive pulp, which is rich i n oil. Polymers were solubilised from the CWM by sequential extraction with rans-1,2-cyclohexanediamine-N,N,N',N'-tettraacetic acid, sodium salt; Na2CO3; 1 M KOH; 4 M KOH; and 4 M KOH+borate to leave the cellul ose-rich residue (CR). A suspension of this residue, on neutralisation , released a pectic material, to give residue CR1. The residue CR1 con tained cross-linked pectic polysaccharides and some cell wall glycopro teins which were solubilised with chlorite-acetic acid. The polymers f rom the Various extracts were fractionated by graded precipitation wit h ethanol prior to anion-exchange chromatography, and selected fractio ns were subjected to methylation analysis. Closely related pectic poly saccharides rich in arabinose were the major components of the cell wa lls and they differed in their ease of extraction from the wall matrix . Significant amounts of acidic xylans were isolated from the precipit ates obtained on neutralisation of the 1 M KOH extracts, and a large p roportion of these would have been derived from the lignified sclereid s; the xyloglucans from the supernatant fractions had xylans associate d with them. However, significant amounts of xyloglucans associated wi th glucomannans, but virtually free of xylans, were isolated from the 'neutral fractions' of the supernatant solutions from the 4 M KOH and 4 M KOH+borate extracts. These 'neutral fractions' also contained sign ificant amounts of hydroxyproline-rich cell wall glycoproteins. The an omeric configurations of the sugars in the glucuronoxylans were determ ined by C-13 NMR spectroscopy. The structural features of the wall pol ymers are discussed in relation to the structure of the cell wall of t he fruit pulp.