Isolation and characterization of insoluble date (Phoenix dactylifera L.) fibers

A comparative study of water insoluble fiber extraction and characterization was carried out in three potential cultivars of palm dates (Phoenix dactylifera L.): Barhee, Sultana and Owadi. Insoluble date fiber was extracted by multistage water extraction of date flesh using microwave (MW) heating followed by freeze-drying, and grinding. High-performance liquid chromatography (HPLC) analysis confirmed the absence of sugars in the fiber after the 6th extraction. The focus of this study was to characterize water insoluble date fiber through various techniques so that it can be used as an important ingredient in food formulation. The particle size of the fiber was measured by dynamic light scattering, and the particle diameters ranged between 700 and 1000 nm. The elemental determinations were performed by inductively coupled plasma optical emission spectrometry (ICP OES) which confirmed that date fibers are rich in potassium, calcium and magnesium (1.5-2.4 g/kg) and low in sodium content. Date fibers showed a high water and oil holding capacity. There were significant differences in tristimulus color values, mineral contents, water and oil holding capacities among date cultivars. These date fibers are good dietary sources with rich in mineral contents and have potential for development of health related foods.

► Insoluble date fiber was obtained through multistage microwave assisted hot water extraction. ► Date fiber particles are in nano-scale size. ► Fibers rich in minerals especially potassium. ► Water and oil holding capacities of fibers are very high. ► A potential ingredient for functional foods.