Date (Phoenix dactylifera L.) polysaccharides: a review on Chemical structure and nutritional properties

Polysaccharides are polymers of sugars linked by glycosidic bonds. They have many nutritional benefits, including prebiotic effects, anti-inflammation, and gut microbiota modulation. Molecular structure investigation helps to understand polysaccharides’ functional, conformational properties and biological activities, facilitating their applications in food and nutraceuticals products. Date fruit (Phoenix dactylifera L.) is an ancient plant cultivated in tropical and subtropical areas. The most abundant bioactive compounds of date fruit are polysaccharides. Several investigations reported that date polysaccharides are biologically active compounds. Date flesh contains around 14% polysaccharide; it constitutes 80% of date seed weight (dry based). Date flesh polysaccharides consist of a particular type of (1→3)-β-D-glucopyranosyl residues with (1→6)-linked branched saccharide residues. Date seed also contains xylan as the primary hemicellulose polymer. Xylan structurally consists of β-1,4-linked D-xylose as the main string with different side chains like L-arabinose, D-galactose, and acetyl groups. The structural analysis of polysaccharides is possible through several specialized techniques. Molecular weight-based separation, monosaccharide composition, linkage patterns, anomeric configuration, and sequences of monosaccharides are the essential properties to be characterized in these investigations. The current review collects comprehensive information about date polysaccharides’ chemical and nutritional properties.