Xyloglucan and hemicelluloses in the cell wall during apple fruit development and ripening

Apple fruit (Malus domestica Borkh. cv. Braeburn) were harvested during fruit development. The tissue was treated with phenol, acetic acid and water (PAW) to deactivate enzymes followed by alpha-amylase in H2O to remove starch. Water soluble polysaccharides were obtained from both fractions. The hemicelluloses were extracted from apple cell walls with 6 M NaOH. The carbohydrate composition of the cell wall fractions and the molecular weight of the hemicelluloses were determined. There was no change in the molecular weight profile of hemicellulose fractions or of xyloglucan polymers as obtained by HPLC with a size exclusion column. The cell wall changes in relation to cell expansion mechanisms are discussed. (C) 1997 Elsevier Science Ireland Ltd.