Impact of Deep Eutectic Solvents on Extraction of Polyphenols from Grape Seeds and Skin

Abstract

In the past few years, research efforts have focused on plant exploitation for deriving some valuable compounds. Extraction has been usually performed using petrochemical and volatile organic solvents, but nowadays, increased recognition of environmental pollution has prompted the utilization of green solvents as alternatives. Therefore, the aim of the present study was to exploit deep eutectic solvents (DES) (choline chloride: citric acid and choline chloride: glucose) as solvents for extracting valuable phenolic antioxidants from grapes. Investigation was conducted on ten grape varieties, observing seeds and skin as different matrix. Total polyphenol content (TPC) was determined by Folin-Ciocalteu spectrophotometric microassay. Antioxidant activity was investigated using four different tests and results were combined in a unique Antioxidant Composite Index (ACI) to reveal comprehensive information about this biological activity. Polyphenol compounds were identified and quantified with the aim of HPLC-diode array detector (DAD). Overall results support that DES (particularly choline chloride: citric acid) were comparable to conventional solvent, and in most cases even outperformed acidified aqueous ethanol (concerning extraction efficiency and antioxidant activity). Regardless of varietal distinctions, grape seeds have higher antioxidant capacity compared to grape skin, and such findings are according to their phenol compound concentrations.

Discrimination of Kyoho grape (Vitis labruscana) skin, seed and flesh antioxidant activities by solvent extraction: application of advanced chemometrics

“…The presence of these phenolic compounds in grape skin, seed and flesh extracts were in accordance with the phenolic compounds available in different grape skin, seed and pulp extracts (Pantelić et al, 2016). The presence of major phenolic compounds, such as gallic acid, catechin and epicatechin in grape skin and seed extracts, were also reported by Dabetić et al (2020). However, it is important to note that each grape cultivar has its unique set of phenolic compounds based on differences in cultivars, environmental conditions and harvesting time.…”

“…The presence of major phenolic compounds, such as gallic acid, catechin and epicatechin in grape skin and seed extracts, were also reported by Dabetić et al . (2020). However, it is important to note that each grape cultivar has its unique set of phenolic compounds based on differences in cultivars, environmental conditions and harvesting time.…”

Ultrasound-Assisted Extraction of Anthocyanins Using Natural Deep Eutectic Solvents and Their Incorporation in Edible Films

“…The lyophilization method is based on freeze-drying the solution until a viscous liquid is obtained [ 10 , 11 ]. This method is often preferred for the extraction of heat-sensitive compounds such as anthocyanins [ 12 , 13 ]. The principal advantages of NADES are that their interaction confer excellent physical and chemical properties, such as low volatility, nonflammability, and adjustable viscosity [ 10 , 14 , 15 ], giving NADES solubilizing behavior that is different from other conventional solvents and has been used more recently in combination with ultrasound energy in order to increase extraction yield of natural products [ 16 , 17 , 18 , 19 , 20 ].…”

COSMOtherm as an Effective Tool for Selection of Deep Eutectic Solvents Based Ready-To-Use Extracts from Graševina Grape Pomace

“…The advantages of DES as extraction media are already known and proven, meaning that they are promising solvents for the extraction of the highest content of polyphenols and are safe to use [17][18][19][20]. DES are a mixture of a hydrogen bond donor (HBD), which can be sugars, polyols, amino acids, amides and a hydrogen bond acceptor (HBA) such as choline chloride in a defined stoichiometric ratio.…”