A composition of chemically purified soluble mannans from legumes' seeds (e.g. Ceratonia siliqua, Caesalpinia spinosa Trigonelle foenum-graecum, and Cyamopsis tetragonolobus) and their use in the assembly of palatable dietary supplements is disclosed herein. The fractionation process provides high-quality physiologically soluble, chemically modified and purified homogeneous size polysaccharide fibers, devoid of natural impurities, for example proteins, alkaloids, glycoalkaloids, and/or environmental impurities including heavy metals, agricultural residues and microbial toxins. This process provides hypoallergenic dietary fibers devoid of any potential allergens, cytotoxins, and gastrointestinal toxins. A sequential process for assembly of the soluble fibers with plurality of molecular weights to create a time controlled dissolution of the functional high and low molecular weight fibers for improving solubility and palatability with improved dietary performance in the oral and gastro-intestinal system is also disclosed herein.
