Fundamentals of Microwave Extraction

Veggi, Priscilla C.; Martínez, Julián; Meireles, M. Angela A.

doi:10.1007/978-1-4614-4830-3_2

Cited by 141 publications

(153 citation statements)

References 82 publications

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“…As a result of these processes, hydrogen bonds are disrupted, which improves the solvent penetration into the matrix, allowing the extraction of components (22). Aside from the applied method, the extraction of phenolics is affected by many factors such as the type and polarity of the used solvent, physical and chemical characteristics of the samples, time and temperature of extraction, sample-to-solvent ratio and the characteristics of the matrix including particle size (23)(24)(25). Furthermore, the efficiency of the extraction of the phenolics by MAE is affected by the microwave power which controls the set temperature (25,26).…”

Section: Mae and Other Advanced Techniquesmentioning

confidence: 99%

“…Theoretically, when the solvent has high dielectric constant and dielectric loss constant, the capacity of the solvent to absorb the microwave energy is high (25,27). Depending on the values of these constants, the most suitable solvents for the MAE of plant bioactive compounds are water, ethanol, acetone, methanol, propan-2-ol and acetonitrile (28).…”

Section: Mae and Other Advanced Techniquesmentioning

confidence: 99%

“…The increase of temperature and extraction time results in the improved extraction yield, but high temperatures and prolonged extraction time may cause the degradation of the thermolabile bioactive compounds (29,30). In order to avoid degradation and oxidation, it is crucial to select properly the extraction temperature and time of MAE, which is quite short in comparison with conventional techniques (25). Dragović-Uzelac et al (24) concluded that extending the extraction time from 3 to 9 min increased the extraction yield of sage extracts and at 9 min the maximum extraction was achieved.…”

Section: Mae and Other Advanced Techniquesmentioning

confidence: 99%

“…The diameter of 90 % of the particles was smaller than 349 μm. Finer particles of the sample enhance penetration of the microwaves (25) and increase the contact surface area of the sample and the solvent material, which can result in the improvement of extraction efficiency (25,26).…”

Section: Plant Materialsmentioning

confidence: 99%

“…From the results shown in Table 2, it is clear that the aqueous solution of ethanol was more efficient solvent than the aqueous solution of methanol in extracting TPC, TF and total flavonols from the extracts of blackthorn flowers, regardless of the volume fraction in the solution. Higher antioxidant capacity of the extracts was also evaluated in ethanol solutions, although ethanol has lower dielectric constant (24.3) and dielectric loss constant (2.500) than methanol (32.6 and 6.400, respectively) (25), which can lead to a conclusion that differences in these constants do not differ enough to cause major distinctions in extraction yield. Furthermore, the extraction of phenolics depends on many other factors (the interactions between the sample and the solvent, the solubility of the sample in the solvent, the hydrophobicity and acid-base properties of the sample and solvent, etc.).…”

Section: Influence Of Solvent Type and Volume Fraction Of Alcohol In mentioning

confidence: 99%

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The Effect of Microwave-Assisted Extraction on the Phenolic Compounds and Antioxidant Capacity of Blackthorn Flowers

Lovrić

Putnik

Jukić

et al. 2017

Food Technol. Biotechnol.

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Blackthorn or sloe (Prunus spinosa L.) from the family Rosaceae is a widespread wild plant growing from south--central Europe down to eastern Asia Minor and northwards to Scandinavia in open woodlands and forest margins. Nearly all parts of the plant including fruit, bark, root, leaves and flowers have been used since ancient times for the treatment of various ailments. The blackthorn flowers, which are usually processed by drying and used as tea, syrup, fresh juice or tincture to treat various diseases, may have wide potential applications in food and pharmaceutical industries (1,2). Despite a great potential and the long tradition of use in folk medicine, systematic phytochemical investigations of this plant are still missing. Previous investigations refer mainly to flavonoid SummaryThis research was undertaken to investigate the influence of extraction parameters during microwave-assisted extraction on total phenolic content, total flavonoids, total hydroxycinnamic acids and total flavonols of blackthorn flowers as well as to evaluate the antioxidant capacity by two different methods (2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity and ferric reducing antioxidant power assays). The investigated extraction parameters were: solvent type and volume fraction of alcohol in solvent (50 and 70 % aqueous solutions of ethanol and methanol), extraction time (5, 15 and 25 min) and extraction temperature (40, 50 and 60 °C) controlled by microwave power of 100, 200 and 300 W. Multivariate analysis of variance (MANOVA) was used to evaluate the differences at a 95 % confidence level (p≤0.05). The obtained results show that aqueous solution of ethanol was more appropriate solvent for extraction of phenolic compounds (total flavonoids, total hydroxycinnamic acids and total flavonols) than aqueous solution of methanol. The amount of phenolic compounds was higher in 70 % aqueous solution of ethanol or methanol, while higher antioxidant capacity was observed in 50 % aqueous solution of methanol. Higher temperature of extraction improved the amount of phenolic compounds and also antioxidant capacity determined by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity assay. Extensive duration of extraction (15-to 25-minute interval) has a significant effect only on the increase of total phenolic content, while specific phenolic compound content and antioxidant capacity were the highest when microwave extraction time of 5 min was applied.

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Section: Mae and Other Advanced Techniquesmentioning

confidence: 99%

Section: Mae and Other Advanced Techniquesmentioning

confidence: 99%

Section: Mae and Other Advanced Techniquesmentioning

confidence: 99%

Section: Plant Materialsmentioning

confidence: 99%

Section: Influence Of Solvent Type and Volume Fraction Of Alcohol In mentioning

confidence: 99%

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The Effect of Microwave-Assisted Extraction on the Phenolic Compounds and Antioxidant Capacity of Blackthorn Flowers

Lovrić

Putnik

Jukić

et al. 2017

Food Technol. Biotechnol.

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Betalains

Miguel

2019

Encyclopedia of Life Sciences

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For long time ago that red beetroot (betalains) has been used as food colouring agent. The development of the organic synthesis led to the production of cheaper food synthetic colorants derived from aniline and other organic compounds that also presenting higher chemical stability and tinctorial strength than natural ones. However, consumers' growing interest in natural products shifted the research goal towards the natural colorants with the objective to improve their chemical stability in diverse food matrices and to find less time‐consuming and more environmental friendly techniques of extraction. Beyond the colouring property of betalains, they exhibit beneficial properties for human health, although their transformations in the organism do not permit explain such biological properties, unless their metabolites also possess activity. This is other research field that starts increasing. Plant and microorganism biotechnology can be a tool for obtaining new natural betalains as well as for enlightening their biosynthetic pathways. Key Concepts New data on the betalain biosynthesis. Betalain bioavailability in animals and humans. Betalain beneficial properties and their molecular mechanisms. Betalains as natural pigments. Encapsulation of betalains.

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Dielectric properties in microwave‐assisted solvent extraction—Present trends and future outlook

Ibrahim

Zaini

2018

Asia-Pacific J Chem Eng

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Fundamentals of Microwave Extraction

Cited by 141 publications

References 82 publications

The Effect of Microwave-Assisted Extraction on the Phenolic Compounds and Antioxidant Capacity of Blackthorn Flowers

The Effect of Microwave-Assisted Extraction on the Phenolic Compounds and Antioxidant Capacity of Blackthorn Flowers

Betalains

Dielectric properties in microwave‐assisted solvent extraction—Present trends and future outlook

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