Two fractions of date-pits fibers were developed by alkaline digestion of whole date-pits powder at 70 °C for 24 h, one from the residue and other one from the supernatant after digestion. Residue and supernatant fibers showed higher hygroscopicity as compared to the date-pits powder (P < 0.05), while there was no significant difference between them (P > 0.05). Similar trends were also observed for water absorption and solubility. Higher absorption indicated that treated fibers could hold more water with higher swelling capacity. In addition, higher FTIR absorption bands of the residue and supernatant fibers at the selected functional groups indicated the molecular damage of the date-pits after digestion. Multivariate analysis of the FTIR spectra bands showed that date-pits powder, residue and supernatant fibers possed different molecular structure. Rigid proton mobility increased in the case of residue and supernatant fibers as compared to the date-pits powder, while mobility of semi-rigid and mobile protons decreased in the cases of residue and supernatant fibers. This indicated that the molecular structural damage occurred by alkaline treatment, and this increased mobility of the semi-rigid and mobile pools of protons and interfering each other, thus reduced the resultant mobility of these pools of protons. It was also evident that extracted supernatant fibers showed the aluminum chelating ability, thus had the ability to reduce aluminum toxicity. Graphical Abstract: [Figure not available: see fulltext.].
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