Ultrasound pretreatment as an alternative to improve essential oils extraction

Abstract

Essential oils are substances originated from plants in general. These compounds are well known to have a high biological activity, specially the antioxidant and antimicrobial. Several extraction techniques are employed to obtain these substances. However, the majority of these techniques require a long extraction time. In this sense, innovative and alternative extraction techniques, such as ultrasound, have recently been the target of studies. In view of the small amount of publications using ultrasonic pretreatment, this review aimed to congregate current relevant information on ultrasound-assisted extraction of essential oils. In this sense, theoretical aspects, such as the main factors that influence the performance of this technique as well as the advantages and disadvantages of the use of ultrasound as an environmental friendly alternative technique to improve the extraction of essential oil in comparison to traditional methods, are shown. Considering the available studies in the literature on essential oil extraction using ultrasonic pretreatment, low frequencies ranged from 20 to 50kWz and times ranged from 20 to 40min were used. The use of ultrasonic pretreatment represents a time reduction to near 70% in relation to the conventional hydrodistillation. Also, these conditions enabled a growth in the extraction of bioactive compounds and consequently improving the antioxidant and antimicrobial activities of essential oils.

Valorization of Sweet Lime Peel for the Extraction of Essential Oil by Solvent Free Microwave Extraction Enhanced with Ultrasound Pretreatment

“…The second stage involves the external diffusion of soluble constituents through the porous structure of the residual solids and its transfer from the solution in contact with the particles to the bulk of the solution [ 27 ]. The use of ultrasonic pre-treatment helps to reduce the extraction time and enabled a growth in the extraction of bioactive compounds and consequently improving the antioxidant and antimicrobial activities of essential oils [ 28 ].…”

Strategies for the synthesis of fluorinated polyesters

“…19 The increase of the surface contact created might have also accelerate the polymerization reaction. [20][21][22] The vacuum effect on polyesters synthesis is of extreme importance since the residual alcohols and water can be further eliminated from the reaction under higher vacuum, which facilitates the chain growth of copolyesters. It is also noteworthy the conversion differences observed, for the same reactional conditions, between the three uorinated di-esters starting reactants.…”

Optimal Extraction of Ocimum basilicum Essential Oil by Association of Ultrasound and Hydrodistillation and Its Potential as a Biopesticide Against a Major Stored Grains Pest

“…Considering that the quality of the oil is related to its chemical composition, the choice of an adequate extraction method is extremely important [ 5 ]. The employed method should not influence the composition and avoiding the decomposition of compounds of interest, in order to maintain the quality of the final product [ 6 , 7 ].…”

“…Ultrasonication is another promising technique that has been applied in the pre-treatment of plant parts. It is applied to avoid the use of solvents and reduce the processing time for the extraction of essential oils [ 5 ]. The technique has also been applied to improve the extraction of polysaccharides and essential oils from plant material, mainly through the phenomenon of cavitation [ 15 , 16 ].…”