engleski

Green extraction of polyphenols from whole cocoa beans

Objectives Conventional extraction techniques for plant phenolics are usually associated with high organic solvent consumption and long extraction times. Aiming to design a greener extraction method for cocoa beans polyphenols, natural deep eutectic solvents (NADES) could be combined with non-conventional energy sources. NADES are a green alternative to conventional solvents that can be coupled with highly efficient microwave-assisted and ultrasound- assisted extraction methods (MAE and UAE, respectively). Microwaves and ultrasound can also be applied simultaneously. Methods Three different NADES have been tested and compared. The best mixture was used for the extraction optimization under ultrasound and microwaves (UAE and MAE). The identification and quantification of phenolic compounds was performed by HPLC. Results NADES capacity to extract phenolic compounds varied considerably according to the target phenolic compounds and the NADES itself. In general, it was found that extraction efficiency strongly depends on hydrogen bond donor (HBD). In the case of total polyphenols (sum of all quantified polyphenols), the highest efficiency was obtained with choline chloride:glycerol (ChGly), followed by choline chloride:glucose (ChGlc) and choline chloride:citric acid (ChCit). The comparison with aqueous ethanol (60%, v/v) showed the higher polyphenols yields in NADES’ extracts. Comparison among MAE, UAE, MAE/UAE, extraction efficiency increased in the following order UAE < MAE/UAE < MAE. The use of NADES coupled with ultrasound and microwave irradiation could lead to highly efficient and truly eco- friendly extraction procedure.

ultrasound ; microwaves ; simultaneous ultrasound/microwaves ; natural deep eutectic solvents.

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