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Reproducible Ethanol-Induced Precipitation and Systematic Characterization of an α-D-Glucopyranose-Rich Solid from Khalas Date Fruit (Phoenix dactylifera L.)

Year: 2026
Type: article
Abstract: In an attempt to prepare ethanolic extracts of date fruit (Phoenix dactylifera L.) from the Khalas variety, a white solid precipitate was reproducibly obtained from three independent batches. A systematic analytical approach established that the isolated solid consisted predominantly of α-D-glucopyranose together with a small amount of D-fructose. TLC indicated monosaccharide behavior, LC–MS confirmed the presence of hexose species, and NMR spectroscopy established α-D-glucopyranose as the predominant component while providing spectroscopic support for a minor D-fructose component. Following identification of these two hexoses, polarimetric analysis based on their opposite specific rotations yielded an estimated composition of 93.8% D-glucose and 6.2% D-fructose under the applied binary glucose–fructose model. The α-anomeric proton (H-1) appeared as a doublet at δ 5.20 ppm (J = 3.5 Hz), consistent with an axial–equatorial relationship between H-1 and H-2. Mutarotation in aqueous solution shifted the equilibrium toward the thermodynamically more stable β-anomer, as evidenced by the decrease in the relative integral of the α-anomeric doublet at δ 5.20 ppm and the corresponding increase in the β-anomeric doublet at δ 4.62 ppm (J = 8.0 Hz), consistent with a diaxial relationship between H-1 and H-2. The present findings demonstrate the reproducible direct ethanol-induced isolation of an α-D-glucopyranose-rich solid from Khalas date fruit without prior aqueous extraction, together with anomer-specific characterization of the isolated material and its subsequent mutarotation in aqueous solution.
Source: Foods
DOI: 10.3390/foods15203632
Language: English
Subfield: Plant Science
Open Access status: gold
Estimated APC paid: $3,499
OpenAlex ID: W7221620554
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Cites: 32
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