Optimization of ultrasound-microwave assisted acid extraction of pectin from potato pulp by response surface methodology and its characterization

• Published in: Food chemistry Vol. 289; pp. 351 - 359
• Main Authors: Yang, Jin-Shu, Mu, Tai-Hua, Ma, Meng-Mei
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15-08-2019
• Subjects: Acetylation; Hexuronic Acids - chemistry; Methylation; Microscopy, Electron, Scanning; Microwaves; Pectin; Pectins - analysis; Pectins - chemistry; Pectins - isolation & purification; Plant Extracts - chemistry; Plant Tubers - chemistry; Potato pulp; Solanum tuberosum - chemistry; Spectroscopy, Fourier Transform Infrared; Structural characteristics; Temperature; Ultrasonics; Ultrasound-microwave assisted acid extraction; d-Galactose (PubChem CID: 6036); BBD; Trifluoroacetic acid (PubChem CID: 6422); DM; Rha; Mw; Structural characteristics; SD; ANOVA; FTIR; RG-I; MF; Potato pulp; UMAE; RG-II; Ethanol (PubChem CID: 702); D2O; R2; Hydrochloric acid (PubChem CID: 313); GlcA; Sodium bisulfite (PubChem CID: 23665763); MALLS; Sulfuric acid (PubChem CID: 1118); l-Rhamnose (PubChem CID: 25310); Potassium bromide (PubChem CID: 253877); Xyl; Pectin; GalA; SEC; Ara; NMR; Sodium hydroxide (PubChem CID: 14798); Gal; CV; RI; SEM; Man; d-Galacturonic acid (PubChem CID: 439215); Ultrasound-microwave assisted acid extraction; DA; HG; Glc
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2019.03.027

•Potato pectin was obtained using ultrasound-microwave assisted HCl extraction.•The optimal extraction parameters were obtained by response surface methodology.•The maximum pectin yield reached to 22.86 ± 1.29% under the optimal conditions.•The branched RG-I domain (>60 mol%) was predominant in the potato pectin.•Potato pectin was the low methoxyl pectin with high degree of acetylation.
The ultrasound-microwave assisted HCl extraction of pectin from potato pulp was optimized using the response surface methodology. Effects of extraction temperature, pH, and time on the yield were evaluated, and structural characteristics of pectin extracted under optimal conditions were determined. The yield was 22.86 ± 1.29% under optimal conditions of temperature 93 °C, pH 2.0, and time 50 min. The obtained pectin was rich in branched rhamnogalacturonan I (61.54 mol%). Furthermore, the pectin was a low-methoxyl (degree of methylation, 32.58%) but highly acetylated (degree of acetylation, 17.84%) pectin and the molecular weight was 1.537 × 105 g/mol. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance indicated that pectin had a linear region of α-1, 4-linked galacturonic acids which could be methyl and acetyl-esterified, and rhamnose linked with galacturonic acid to form rhamnogalacturonan which was branched with side chains. Scanning electron microscopy showed most of pectin had a lamellae structure.