Extraction for profiling free and bound phenolic compounds in tea seed oil by deep eutectic solvents

Abstract

Bound phenolic compounds have rarely been reported in vegetable oils and this may be due to little research about the extraction. Deep eutectic solvents (DESs), recently applied in the extraction of phenolic compounds as alternatives to organic solvents, were adopted in the extraction of free and bound phenolic compounds from tea seed oil in this work. First, the phenolic compounds were analyzed by ultra‐high‐performance liquid chromatography with quadrupole‐time‐of‐flight and triple‐quadrupole tandem mass spectrometry (UHPLC‐Q‐TOF‐MS/MS) for characterization and UHPLC‐QqQ‐MS/MS for quantification and 25 phenolic compounds were found to exist in both free and bound forms. Then, DESs were screened for extraction of free and bound phenolic compounds from tea seed oil as the pretreatment for analysis and the results showed that hydrogen bond donors (HBDs) and temperature significantly affected the extraction efficiency of DESs. Finally, free phenolic compounds (83.91 µg/g) and bound phenolic compounds (25.71 µg/g), extracted by the DES with glycerol as HBD at 50 °C, were 51.0% and 93.2% higher than those extracted by methanol/water (60%, v/v), respectively. This work not only advanced the basic data of phenolic compounds in tea seed oil but also explored an efficient extraction method for scientific analysis of free and bound phenolic compounds.

Extraction Systems and Analytical Techniques for Food Phenolic Compounds: A Review

“…Of special interest are natural DES or NADES, which can even be present in food products without further purification of the extracts if they are, for example, safe for consumption and their use is approved by food safety administrations [ 73 ]. The properties of the DES solution can be modulated by changing its composition (compounds mixed and ratio) to increase the efficiency of the extraction of phenolic compounds, both free and bound ones [ 74 ].…”

Deep eutectic-like solvents: Promising green media for biomass treatment and preparation of nanomaterials

“…When the temperature is rather low, the viscosity increases and results in deficiency of interaction between the reactants (Procentese et al 2015;Mamilla et al 2019). However a higher temperature may lead to the condensation of reactants, such as the lignin (Alvarez-Vasco et al 2016), and that is also detrimental to the biomass treatment (Kohli et al 2020), even reducing the bioactivity of the extracts (Hsieh et al 2020;Wang et al 2020a). Furthermore, the solid-liquid ratio is another important factor.…”

Deep Eutectic Solvents for the Extraction of Bioactive Compounds from Natural Sources and Agricultural By-Products

“…An exhaustive revision of the literature shows that, apart from vegetables, plants, fruits or agricultural by-products, other natural matrices have also served as source of valuable compounds and as occur with previous sources, the use of NADESs as extraction solvents has been also carried out. In this sense, oils obtained from citric, cereals, olives, and palm [40][41][42][43][44][45][46] have been the products most widely evaluated using DESs, although flour [47], eggs [48] and milk [49] as well as nonagricultural by-products [10,50] have been also investigated. As can be seen in Table 3, the studies were focused on the search of different and varied types of molecules including phenolic compounds [40][41][42]46], flavonoids [40,43], terpenoids [10,42,44], proteins [48], lignans [45] or minerals [50].…”

“…[47] In this kind of application, again ChCl was the preferred HBA combined with alcohols, organic acids, sugars or urea [40,41,[43][44][45][46]50] although other quaternary ammonium salts combined with alcohols [42,47,48], lactic acid combined with glucose [49] or terpenes (menthol) together with myristic acid [10] have been also applied. In all cases, natural components were used, thus the application of NADESs has been the choice in the studies developed so far in this area.…”

“…However, the selection of the final applied solvent was based, in most cases, on the results obtained from previous studies in which several HBDs or even HBAs and variated molar ratio combinations were explored to reach the best extraction performance. In this sense, it should be highlighted the work carried out by Wang et al [41], in which liquid-liquid extraction (LLE) using NADESs was applied for profiling free and bound phenolic compounds in tea seed oil. The authors tested different binary and ternary DESs using ChCl as HBA and xylitol, malonic acid, glycerol, ethylene glycol and propylene glycol as HBDs and formed using variated molar ratio.…”