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Ultrasound-microwave assisted extraction of pectin from fig (Ficus carica L.) skin: Optimization, characterization and bioactivity

Gharibzahedi, Seyed Mohammad Taghi, Smith, Brennan, Guo, Ya
Carbohydrate polymers 2019 v.222 pp. 114992
Ficus carica, Fourier transform infrared spectroscopy, antioxidant activity, arabinose, cytotoxicity, figs, fucose, galactose, glucose, image analysis, irradiation, liquids, mannose, mathematical models, moieties, molecular weight, pectins, rhamnose, scanning electron microscopy, sonication, uronic acids
Four operating parameters in ultrasound-microwave assisted extraction (UMAE) process including sonication time (ST, 10–30 min), microwave power (MP, 300–600 W), irradiation time (IT, 5–15 min), and the liquid to solid ratio (LSR, 10–30 mL/g) on the extraction yield of pectin from fig skin were optimized. The yield (13.97%) of pectin with an average molecular mass of 6.89 × 103 kDa was maximized at 21.35 min ST, 580.9 W MP, 11.67 min IT, and 24.66 mL/g LSR based on a second-order polynomial model (R2 = 0.986) with a high level of significance (p < 0.0001). Field emission-scanning electron microscopy (FE-SEM) imaging and Fourier transform-infrared (FTIR) spectra of the pectin extracted under optimal conditions exhibited a disintegrated network in structural morphology and the main functional groups, respectively. The extracted low-methoxyl pectin (DE = 33.65%) with high lightness contained considerable amounts of uronic acids and neutral monosaccharides (glucose, fucose, arabinose, galactose, rhamnose, and mannose). A strong dose-depended behavior for antioxidant functions and cytotoxic inhibitory activities of pectin against HepG2 and A549 cells was found.