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  • Highly efficient extraction of anthocyanins from grape skin using deep eutectic solvents as green and tunable media.

Highly efficient extraction of anthocyanins from grape skin using deep eutectic solvents as green and tunable media.

Archives of pharmacal research (2015-11-05)
Kyung Min Jeong, Jing Zhao, Yan Jin, Seong Rok Heo, Se Young Han, Da Eun Yoo, Jeongmi Lee
ABSTRACT

Deep eutectic solvents (DESs) were investigated as tunable, environmentally benign, yet superior extraction media to enhance the extraction of anthocyanins from grape skin, which is usually discarded as waste. Ten DESs containing choline chloride as hydrogen bond acceptor combined with different hydrogen bond donors were screened for high extraction efficiencies based on the anthocyanin extraction yields. As a result, citric acid, D-(+)-maltose, and fructose were selected as the effective DES components, and the newly designed DES, CM-6 that is composed of citric acid and D-(+)-maltose at 4:1 molar ratio, exhibited significantly higher levels of anthocyanin extraction yields than conventional extraction solvents such as 80% aqueous methanol. The final extraction method was established based on the ultrasound-assisted extraction under conditions optimized using response surface methodology. Its extraction yields were double or even higher than those of conventional methods that are time-consuming and use volatile organic solvents. Our method is truly a green method for anthocyanin extraction with great extraction efficiency using a minimal amount of time and solvent. Moreover, this study suggested that grape skin, the by-products of grape juice processing, could serve as a valuable source for safe, natural colorants or antioxidants by use of the eco-friendly extraction solvent, CM-6.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
DL-Malic acid, 99%
Sigma-Aldrich
Sucrose, SAJ first grade
Sigma-Aldrich
Ethanol, ≥99.5%
Sigma-Aldrich
Phenol, SAJ first grade, ≥98.0%
Sigma-Aldrich
Citric acid, SAJ first grade, ≥99.5%
Sigma-Aldrich
Phenol, ≥99.0%
Sigma-Aldrich
Ethanol, JIS 300, ≥99.5%, for residue analysis
Sigma-Aldrich
Sucrose, JIS special grade
Sigma-Aldrich
Phenol, ≥99.0%
Sigma-Aldrich
DL-Malic acid, SAJ first grade, ≥99.0%
Sigma-Aldrich
Ethanol, JIS 1000, ≥99.5%, for residue analysis
Sigma-Aldrich
Ethanol, ≥99.5%, suitable for absorption spectrum analysis
Sigma-Aldrich
Ethanol, ≥99.5%, suitable for HPLC
Sigma-Aldrich
Formic acid, JIS special grade, ≥98.0%
Sigma-Aldrich
Ethanol, ≥99.5%, suitable for fluorescence
Sigma-Aldrich
Ethanol, ≥99.5%, SAJ super special grade
Sigma-Aldrich
Ethanol, JIS special grade, ≥99.5%
Sigma-Aldrich
Ethanol, SAJ first grade, ≥99.5%
Sigma-Aldrich
Glycerol, JIS special grade, ≥99.0%
Sigma-Aldrich
Glycerol, SAJ first grade, ≥98.0%
Sigma-Aldrich
Phenol, JIS special grade, ≥99.0%
Sigma-Aldrich
Formic acid, SAJ first grade, 88.0-89.5%
Supelco
Phenol solution, certified reference material, 500 μg/mL in methanol
Supelco
Phenol solution, 5000 μg/mL in methanol, certified reference material
Sigma-Aldrich
Citric acid, ACS reagent, ≥99.5%
Sigma-Aldrich
Glycerol, FCC, FG
Sigma-Aldrich
Phenol, unstabilized, ReagentPlus®, ≥99%
Sigma-Aldrich
Phenol, ACS reagent, ≥99.0%
Sigma-Aldrich
Phenol, puriss., meets analytical specification of Ph. Eur., BP, USP, 99.5-100.5% (GC)
Sigma-Aldrich
Choline chloride, BioUltra, ≥99.0% (AT)