Non‐starch polysaccharides from sunflower (<i>Helianthus annuus</i>) meal and palm kernel (<i>Elaeis guineenis</i>) meal—preparation of cell wall material and extraction of polysaccharide fractions

Abstract

Abstract Two different chemical methods, sequential extraction with alkali and sodium chlorite and treatment with 4‐methylmorpholine N‐oxide (MMNO), were applied to the extraction of non‐starch polysaccharides (NSP) from the enzymically deproteinated, water‐insoluble cell wall materials of sunflower ( Helianthus annuus L) meal and palm kernel (Elaeis guineensis Jacq ) meal. The NSP content accounted for 550 g kg −1 (sunflower meal) and 750 g kg −1 (palm kernel meal) of the cell wall materials. Neither of the treatments alone was capable of solubilising more than about half of the original NSP. Combined treatment using alkali/chlorite followed by MMNO completely dissolved cell wall material from palm kernel meal, whereas a small residue (40 g kg −1 of original NSP) was left in sunflower meal. Loss of NSP occurred with both methods (total NSP recovery ranging from 88% for alkali/chlorite extraction of sunflower to 64% for MMNO extraction of palm kernel). Due to differences in solubility revealed upon acidification and/or dialysis, extracts became subdivided into precipitates and soulble fractions. The sugar composition of the resulting fractions enabled a tentative identification of teh major non‐starch polysaccharides; sunflower meal was found to contain cellulose, (acidic) xylans, polyuronide‐containing fractions and xyloglucan; palm kernel meal was found to contain mannans, cellulose and xylans, with the major part of the mannans originating from the endosperm and the xylans being almost exclusively located in the endocarp.