Optimization Of Microwave-assisted Extraction Research Articles

Untargeted metabolomics, optimization of microwave-assisted extraction using Box-Behnken design and evaluation of antioxidant, and antidiabetic activities of sugarcane bagasse.

The fruit wastes, in particular agricultural wastes, are considered potential and inexpensive sources of bioactive compounds. The current study was aimed at the preparation of an optimized extract of sugarcane bagasse using microwave-assisted extraction (MAE) technology and comparative evaluation of chemical composition, antioxidant, and antidiabetic activities with extract prepared through maceration technique. Box-Behnken Design (BDD) with response surface methodology was applied to observe interactions of three independent variables (ethanol concentrations [%], microwave power [W], and extraction time [min]) on the dependent variables (total phenolic content [TPC] and antioxidant status via 2,2-diphenyl-1-picrylhydrazyl [DPPH] to establish optimal extraction conditions. The ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) analysis was applied for untargeted metabolite profiling, and in vitro assays were used for evaluation of the antidiabetic and antioxidant potential of the extract. Moreover, an in silico study was used to predict the interaction of five dominant compounds from the UHPLC-Q-TOF-MS profile against the dipeptidyl peptidase-IV (DPP-IV) enzyme. The optimal conditions for the extraction were established at 60% (v/v) ethanol, 500 W microwave power, and 5 min time with TPC 12.83 ± 0.66 mg GAE/g d.w. and DPPH 45.09 ± 0.07%. The UHPLC-Q-TOF-MS analysis revealed the presence of a total of 106 compounds in the extract. Moreover, the extract prepared through MAE technology presented higher TPC and DPPH findings than the extract prepared through maceration. Similarly, the extract was also found with good antidiabetic activity by inhibiting the DPP-IV enzyme which was also rectified theoretically by a molecular docking study. The current study presents a sustainable and an optimized approach for the preparation of sugarcane bagasse extract with functional phytoconstituents and higher antidiabetic and antioxidant activities.

Extraction of phenolic compounds from edible flowers (Phlogacanthus thyrsiflorus) using ultrasound‐microwave‐assisted extraction and its screening by HPLC

AbstractPhlogacanthus thyrsiflorus flowers have been consumed as a traditional delicacy in the north‐eastern region of India. The present investigation utilized the microwave‐assisted extraction (MAE) technique in conjunction with an ultrasound pretreatment (at 250 W for 15 min) to extract phenolic compounds from Phlogacanthus thyrsiflorus flowers. Here, independent factors for optimization of MAE were microwave power (300, 500, and 700 W) and extraction time (2, 4, and 6 min), and responses were total phenolic content (TPC), total flavonoid content (TFC) and DPPH (2,2‐dipheny‐1‐picrylhydrazyl) activity. For the experimental design, a Response surface methodology and a central composite design were followed. The optimum MAE condition was found at microwave power 700 W for 5 min resulting 30.204 mg GAE/g TPC, 81.26% DPPH and 22.50 mg QAE/g of TFC. The extraction of phenolic compounds was significantly impacted by both the microwave power and the extraction time. The high‐performance liquid chromatography (HPLC) analysis detected various phenolic compounds in both conventional and MAE extracts. However, compared to conventional extract, the majority of the identified phenolic compounds were found to be higher in quantities in MAE extract. These results highlighted that MAE‐optimized flower extract could be beneficial as a functional ingredient for food product development.Practical applicationsPhlogacanthus thyrsiflorus is a highly nutritious flower with medicinal properties. Though traditionally edible flowers have been consumed in the northeastern part of India but people are still neophobic and there is scanty awareness available regarding the benefits of consuming edible flowers. This scientific justification regarding the advantages of edible flowers makes them appealing for future novel use in food technology and also for further scientific study. High perishability of flowers makes them limited for market viability and extraction of its phenolic compounds is one of the novel solutions to utilize the flowers before spoilage. Also, using ultrasound as a pretreatment could enhance the efficiency of microwave‐assisted extraction techniques for a higher yield of phenolic compounds. Microwave‐assisted extraction technique as its novel and was proven an easy successful extraction technique on this flower. Also, the study of phenolic compounds through HPLC provides important information regarding the presence of various phenolic compounds in the Phlogacanthus thyrsiflorus flower. This research can be supportive of both food technology and the medicinal industry.

Combinatorial preparation and structural characterization of anthocyanins and aglycones from Purple-heart Radish for evaluation of physicochemical stability and pancreatic lipase inhibitory activity

In this study, an efficient approach to preparation of different anthocyanins from Purple-heart Radish was developed by combining microwave-assisted extraction (MAE), macroporous resin purification (MRP) and ultrasound-assisted acid hydrolysis (UAAH) for evaluation of physicochemical stability and pancreatic lipase (PL) inhibitory activity. By optimization of MAE, MRP and UAAH processes, the anthocyanins reached the yield of 6.081 ± 0.106 mg/g, the purity of 78.54 ± 0.62 % (w/w) and the content of 76.29 ± 1.31 % (w/w), respectively. With high-resolution UHPLC-Q-Orbitrap/MS, 15 anthocyanins were identified as pelargonins with diverse glucosides and confirmed by pelargonidin standard. By glycosylation, pelargonins exhibited higher stability in different pH, temperature, light, metal ions environments than that of pelargonidin. However, PL inhibitory assay, kinetic analysis and molecular docking demonstrated that pelargonidin had higher PL inhibitory activity than pelargonins even though with similar binding sites and a dose–effect relationship. The above results revealed that the effect of glycosylation and deglycosylation on PL inhibitory activity and physicochemical stability.

Production of Encapsulated Hydrogel Beads and Sugar-Free Beverage from Gilaburu Fruit Rich in Antioxidants, Antidiabetic Bioactives, and its Microwave-Assisted Extraction Optimization

Production of Encapsulated Hydrogel Beads and Sugar-Free Beverage from Gilaburu Fruit Rich in Antioxidants, Antidiabetic Bioactives, and its Microwave-Assisted Extraction Optimization

Solanesol sequential extraction from tobacco leaves using microwave-ultrasound-assisted extraction (MUAE): MAE optimization

Solanesol (C45H74O) is an aliphatic terpene alcohol of nine isoprene units found in the tobacco plant (Nicotiana Tabacum L.). The long and complex biosynthetic pathway of solanesol makes the extraction method still the best way to obtain solanesol. This work evaluates the optimum conditions for sequential extraction from tobacco leaves using microwave-ultrasound-assisted extraction (MUAE) as a green extraction method. There were two stages of extraction (sequential): first, microwave-assisted extraction (MAE), followed by ultrasound-assisted extraction (UAE). At the MAE stage, dry tobacco powder was extracted with variations of water-to-solid (feed) ratio (S/F) from 1:1 to 10:1 (mL/g), power from 200 to 800 W, and time from 0.5 to 2 min. Optimum conditions were obtained at 6:1 (mL/g), 400 W, and 1.5 min, respectively. The UAE stage was fixed with the solvent-to-solid (feed) ratio (S/F), solvent ratio (v/v), time, and temperature of 40:1, 1:2 (PE:ethanolic acid), 30 min, and 40 °C, respectively. The optimum solanesol yield was 3.0 % (w/w), and a nicotine yield of 1.41 % (%w/w) was obtained under the same conditions. The resulting crude solanesol was then purified using silica gel column chromatography (CC), resulting in a purity of 85 %. The yield of extracted solanesol is much higher than in other studies due to the use of fresh leaves and MUAE method.

Optimization of microwave-assisted extraction in the purification of triglycerides from non-edible crude Calophyllum inophyllum oil as biodiesel feedstock using artificial intelligence

Crude nyamplung Calophyllum inophyllum is a potential non-edible feedstock for biodiesel production. Calophyllum Inophyllum oil (CCIO) is a non-edible oil that has a high content of triglyceride (TG) and free fatty acid (FFA). This study aims to optimize microwave-assisted power and extraction time of triglyceride purification from C. inophyllum crude oil for biodiesel. This work deployed Artificial Intelligence (AI) algorithms consisting of eight Machine Learning (ML) algorithms and found the most accurate model, then optimized using the Particle Swarm Optimization (PSO) algorithm.The result of machine learning modelling Random Forest achieved higher accuracy in R-Square and lower Mean Square Error (MSE) than any other models. Overall, in R-Square average across all variables was 0.949 ± 0.026 and the MSE average of 0.097 ± 0.068. This result can be interpreted as a mean deviation between the predicted value and an accurate value of less than 0.1 for all variables. The optimum of the TG compound resulted in the power of 462.3 W and time of 39.12 min that equalled at 84.02% and FFA equalled at 6.92%. The TG have increased by 11% from the reference range, which states conventional methods from crude oil. Comparison with the MAE method has a minimum fitness value difference of 0.0006 but has a smaller accuracy of less than 1%. Implementing this prediction and optimization method can shorten the extraction time by 5.8 min and reduce energy consumption or system work by 130 kJ. This method can be used for input parameter model prediction and parameter optimization in purification for biodiesel feedstock. Further research can be carried out using other artificial intelligence methods to optimize biodiesel production.

Microwave-assisted extraction optimization of sesquiterpene lactones from Inula helenium roots: A sustainable approach to reduce energy consumption and carbon footprint.

Inula helenium roots are consumed as natural flavor components and raw or cooked as food, and their extracts are rich in sesquiterpene lactones such as alantolactone (AL) and isoalantolactone (IAL), which have recently attracted great attention due to their pharmacological properties. The industrial utilization of these compounds requires the development of green, efficient, cost-effective, and sustainable extraction protocols. Therefore, this study focused on the optimization of microwave-assisted extraction (MAE) process variables using Face-Centered Central Composite Design (FC-CCD). Then, maceration was applied as a conventional technique, and these techniques were compared in terms of extraction efficiency, morphological changes, antimicrobial activities, carbon emissions, and energy consumption. As a result, optimal MAE conditions, i.e., EtOH: water ratio (X 1) = 100:0, liquid/sample ratio (X 2) = 30:1 mL/g, microwave power (X 3) = 300 W, and irradiation time (X 4) = 5 min, were obtained with AL and IAL yields of 54.99 ± 0.11 (mg/g) and 48.40 ± 0.19 (mg/g), respectively. The extract obtained by MAE had similar or better activity than positive controls in most cases and formed the largest inhibition zones against E. coli (29.5 ± 0.71 mm) and A. niger (34.75 ± 1.06 mm). Morphological changes of I. helenium roots after extraction were observed by scanning electron microscopy. Additionally, MAE was 43.4 times faster than maceration, resulting in 228.6 times less energy consumption and carbon emissions. Based on these findings, it is recommended to use MAE as an industrial green technique for the extraction of sesquiterpene lactones with potential applications in nutraceuticals and food products in terms of sustainable economy and environmental protection.

Optimization of microwave-assisted extraction (MAE) of key phenolic compounds from pigeon pea (Cajanus cajan L.), their characterization, and measurement of their anti-diabetic and cytotoxic potential

Optimization of microwave-assisted extraction (MAE) of key phenolic compounds from pigeon pea (Cajanus cajan L.), their characterization, and measurement of their anti-diabetic and cytotoxic potential

Microwave-assisted extraction optimization and conventional extraction of phenolic compounds from coriander leaves: UHPLC characterization and antioxidant activity

Background: Qualitative and quantitative investigations of bioactive compounds in plant materials are heavily based on the selection of an accurate extraction method. Aims: That’s why; this work consists of a comparative study between Microwave Assisted Extraction (MAE) and Conventional Extraction (CE), based on the total phenolic compounds (TPC) yield, phenolic profile, and antioxidant activity of coriander leaves powder (Coriandrum sativum L.). Material and Methods: MAE was optimized and performed using the Response Surface Methodology (RSM), and was modeled by using a second-order regression equation. While CE was done using the classic water bath method. Results: Under the optimal conditions, the recovery of TPC yield obtained was 37.94 ± 2.06 mg (MAE) vs 44.47 ± 0.57 mg GAE/g DW (CE). The UHPLC characterization showed a close phenolic composition of the two extracts, mainly represented by quercetin glucosides and by dimethoxycinnamoyl hexoside. No significant difference (p>0.05) was recorded in terms of the antioxidant activity of both extracts, as estimated by Ferric reducing antioxidant power (FRAP), Nitric oxide (NO•), and superoxide anion (O2•-) scavenging tests. Conclusions: Hence, the exploitation of MAE has many valuable advantages, as the processing time is brief and the antioxidant activities and phenolic composition were not affected by the extraction process.

Microwave-Assisted Extraction Optimization and Effect of Drying Temperature on Catechins, Procyanidins and Theobromine in Cocoa Beans.

Cocoa beans (Theobroma cacao L.) are an important source of polyphenols. Nevertheless, the content of these compounds is influenced by post-harvest processes. In this sense, the concentration of polyphenols can decrease by more than 50% during drying. In this study, the process of procyanidins extraction was optimized and the stability of catechins, procyanidins, and theobromine to different drying temperatures was evaluated. First, the effectiveness of methanol, ethanol, acetone, and water as extract solvents was determined. A Box-Behnken design and response surface methodology were used to optimize the Microwave-Assisted Extraction (MAE) process. The ratios of methanol-water, time, and temperature of extraction were selected as independent variables, whereas the concentration of procyanidins was used as a response variable. Concerning the drying, the samples were dried using five temperatures, and a sample freeze-dried was used as a control. The quantitative analyses were carried out by HPLC-DAD-ESI-IT-MS. The optimal MAE conditions were 67 °C, 56 min, and 73% methanol. Regarding the drying, the maximum contents of procyanidins were obtained at 40 °C. To our knowledge, this is the first time that the stability of dimers, trimers, and tetramers of procyanidins on drying temperature was evaluated. In conclusion, drying at 40 °C presented better results than the freeze-drying method.

Process Optimization of Microwave-Assisted Extraction of Chlorophyll, Carotenoid and Phenolic Compounds from Chlorella vulgaris and Comparison with Conventional and Supercritical Fluid Extraction

The production of bioactive products from microalgae biomass with efficient and environmentally friendly technologies is a field of great research interest. The present work focuses on the recovery of high-added value bioactive components from Chlorella vulgaris through microwave-assisted extraction (MAE) with aq. ethanol 90% v/v. The effect of extraction temperature (40–60 °C), duration (5–25 min), solvent-to-biomass ratio (20–90 mLsolv/gbiom), and microwave power (300–800 watts) was investigated regarding the extraction yield, extract’s chlorophyll, carotenoid and phenolic content, and antioxidant activity. MAE optimization at 60 °C, 300 watts, 14 min, and 22 mLsolv/gbiom led to 11.14% w/w yield, 63.36 mg/gextr total chlorophylls, 7.06 mg/gextr selected carotenoids of astaxanthin, lutein and β-carotene, 24.88 mg/gextr total carotenoids, 9.34 mgGA/gextr total phenolics, and 40.49 mgextr/mgDPPH IC50 (antioxidant activity indicator). Moreover, the conventional solid-liquid extraction (SLE) with aq. ethanol 90% v/v, the supercritical fluid extraction (SFE) with CO2, as well as SFE with cosolvent addition (10% w/w ethanol), were also performed for comparison purposes. The results revealed that SLE presented the highest yield. However, the non-conventional methods of MAE and SFE led to extracts of competitive or even better quality under significantly shorter extraction duration.

Optimization of Microwave-assisted Extraction Technique for Flavonoids and Phenolics from the Leaves of Oroxylum indicum (L.) Kurtz Using Taguchi L9 Orthogonal Design

Background An experimental design to obtain bioactive ingredients from Oroxylum indicum (L.) Kurtz was performed applying microwave-assisted extraction (MAE). Recently, tremendous research interest and benefits have been observed for extracting active constituents from plant materials using the microwave. Objectives This work aimed to develop an optimized, green, efficient, alternative procedure for extracting flavonoid and phenolic (total flavonoid content [TFC] and total phenolic content [TPC]) from leaves of Oroxylum indicum (L.) Kurtz. Materials and Methods A total of 1 g of the powdered sample was extracted using classical Soxhlet apparatus for 48 hr to ensure exhaustive extraction; simultaneously, maceration and ultrasound-assisted extraction were also carried out using 1 g of the plant sample for 12 hr and 60 min at 25˚C, respectively. The optimization of MAE was done using Taguchi L9 orthogonal design. The optimum operating conditions were microwave power (160 W), soaking time (4 min), irradiation time (4 min), and temperature (57˚C). Results The microwave method has shown 70% higher yield than other conventional techniques in a shorter time, along with increased TFC and TPC. Conclusion The TPC, TFC, and total antioxidant capacity (TAC) values are higher in the extract obtained by MAE extracts in comparison to other techniques. The extraction technique will be an ideal tool to safeguard the thermolabile plant constituents that will be more environmentally friendly.

Characterization and Cytotoxic Activity of Microwave-Assisted Extracted Crude Fucoidans from Different Brown Seaweeds.

Microwave-assisted extraction (MAE) is recognized as a green method for extraction of natural products. The current research aimed to explore the MAE for fucoidans extraction from different brown seaweeds, including Fucus vesiculosus, F. spiralis, and Laminaria saccharina. Following several solvent-extraction pre-treatment steps and MAE optimization, the algal biomasses were extracted in a ratio of 1:25 in 0.1 M HCl containing 2 M CaCl2 for 1.0 min. The results showed that L. saccharina's extract was different from the others, regarding the highest sugar content reached 0.47 mg glucose equivalent/mg extract being confirmed by monosaccharide composition analysis and the lowest fucoidan content and sulfation degree at 0.09 mg/mg extract and 0.13, respectively. Moreover, these findings were confirmed by tentative structural elucidation based on Fourier-transform infrared spectrometry which also showed a different spectrum. However, the MAE enhanced melanoidins formation in products, which was confirmed by the intense band at 1420 cm-1. Interestingly, the results of monomeric composition showed that fucoidan extract by MAE from F. vesiculosus belonged to sulfated galactofucans which are known for their potential bioactivities. Furthermore, the cytotoxic activity of the four fucoidans in concentrations ranging from 4.9 µg/mL to 2500 µg/mL was investigated and correlated with the chemical characterization showing that F. vesiculosus_MAE fucoidan was the most potent and safest. The current research revealed the chemical heterogeneity of fucoidans regarding taxonomical class and used greener extraction method of fucoidans toward the achievement of the UN sustainability goals.

Optimization of microwave-assisted extraction on polyphenol metabolite from Eleutherine bulbosa (Mill.) urb. bulbs using response surface methodology.

Eleutherine bulbosa bulbs, an endemic plant in Indonesia, have enormous potential as raw materials for pharmaceutical products. Therefore, it is necessary to strengthen and develop extraction methods that are easy, rapid, and efficient to enrich targeted secondary metabolites. This study aims to optimize the microwave-assisted extraction (MAE) method conditions for polyphenol metabolite from E. bulbosa bulbs. The MAE method (with different conditions) was applied to extract total polyphenol content (TPC) from E. bulbosa bulbs. TPC values were determined using a 96-well microplate reader spectrophotometry method and Folin-Ciocalteu reagent. The variables of MAE, as an experimental design-independent variable, were involved. The MAE method condition was optimized using response surface methodology (RSM) and Box-Behnken design based on the TPC value. The MAE condition was optimized with 60% ethanol, sample-solvent ratio of 1:10 g/mL, and 50% Watts of microwave power for 10 min. The quadratic regression analysis was achieved to predict the TPC value using the equation: TPC value = 28.63-5.545A +2.211B -0.741C +1.995D - 4.045AB +0.856AC -7.541BC +1.961CD -8.342A2-0.071B2 +1.840C2-1.535D2. For the scale-up confirmation test, a 50-g sample was used to prove the validity of the equation to predict the TPC value, yielding 35.33 ± 2.13 mg gallic acid equivalent/g samples. The optimum of the MAE condition recommended based on the results of RSM analysis can be applied directly to the enrichment of polyphenols metabolite constituent of E. bulbosa easily, cheaply, quickly, and efficiently.

Optimization of Microwave-Assisted Extraction and Matrix Solid-Phase Dispersion for the Extraction of Polyphenolic Compounds from Grape Skin

Polyphenols are organic compounds that can be found in food, especially in fruits, vegetables, and their products. It was shown that their presence significantly affects the properties of food products and that the consumption of food rich in phenolic compounds has a beneficial effect on human health. The subjects of this research were polyphenols: anthocyanins, flavonols, and flavan-3-ols in the skin of grapevine variety Regent. Polyphenols from grape skins were extracted via microwave-assisted extraction (MAE) and matrix solid-phase dispersion (MSPD) as unconventional and green techniques. Therefore, the main aim of this work was to optimize the conditions for the extraction of polyphenolic compounds from grape skin using MAE and MSPD. The extracts were analyzed using high-performance liquid chromatography with a diode array detector and fluorescence detector. Analyses showed that MAE was a very effective method for extracting polyphenolic compounds from grape skin with 10 mL of 60% ethanol for 5 min at 40 °C. The best results for the MSPD extraction of polyphenolic compounds from grape skin were obtained with phenyl as an MSPD sorbent with 10 mL of acetonitrile:water 50:50 v/v as an elution solvent. This scientific research can be used for the better use of grapes as a basis for obtaining flavonoids for commercial purposes.

Polyphenols Recovery from Thymus serpyllum Industrial Waste Using Microwave-Assisted Extraction-Comparative RSM and ANN Approach for Process Optimization.

The aim of this study was to valorize Thymus serpyllum L. herbal dust, the particular fraction distinguished as industrial waste from filter-tea production. This work demonstrated comparable analysis considering model fitting, influence analysis and optimization of microwave-assisted extraction (MAE) of bioactive compounds from the aforementioned herbal dust using face-centered central composite experimental design within the response surface methodology (RSM), as well as artificial neural networks (ANN). In order to increase yield and amount of compounds of interest and minimize solvent, time and energy consumption, the ethanol concentration (45, 60 and 75%), extraction time (5, 12.5 and 20 min), liquid–solid ratio (10, 20 and 30 mL/g) and irradiation power (400, 600 and 800 W) were used as independent variables. Total extraction yield (Y), total phenols yield (TP), as well as antioxidant activity parameters obtained by DPPH and ABTS assays, were selected as responses. It could be concluded that the MAE technique is an efficient approach for the extraction of biologically active compounds from T. serpyllum herbal dust, which represents a high-value source of natural antioxidants with great potential for further use in various forms within different branches of industry.

Towards the Optimization of Microwave-Assisted Extraction and the Assessment of Chemical Profile, Antioxidant and Antimicrobial Activity of Wine Lees Extracts

Wine lees, a sub-exploited byproduct of vinification, is considered a rich source of bioactive compounds, such as (poly)phenols, anthocyanins and tannins. Thus, the effective and rapid recovery of these biomolecules and the assessment of the bioactive properties of wine lees extracts is of utmost importance. Towards this direction, microwave-assisted extraction (MAE) factors (i.e., extraction time, microwave power and solvent/material ratio) were optimized using experimental design models in order to maximize the (poly)phenolic yield of the extracts. After optimizing the MAE process, the total phenolic content (TPC) as well as the antiradical, antioxidant and antimicrobial activity of the extracts were evaluated. Furthermore, Fourier transform infrared spectroscopy (FTIR) was employed to investigate the chemical profile of wine lees extracts. Red varieties exhibited higher biological activity than white varieties. The geographical origin and fermentation stage were also considered as critical factors. The white variety Moschofilero presented the highest antioxidant, antiradical and antimicrobial activity, while Merlot and Agiorgitiko samples showed noteworthy activities among red varieties. Moreover, IR spectra confirmed the presence of sugars, amino acids, organic acids and aromatic compounds. Thus, an efficient, rapid and eco-friendly process was proposed for further valorization of wine lees extracts.

Non-conventional techniques for the extraction of antioxidant compounds and lycopene from industrial tomato pomace (Solanum lycopersicum L.) using spouted bed drying as a pre-treatment

This study aimed to use the non-conventional microwave-assisted extraction (MAE) and pressurized liquid extraction (PLE) techniques for recovering bioactive compounds from tomato pomace, a valuable agro-industrial waste. The raw material was previously dried using a spouted bed dryer and then submitted to extraction with green solvents. A response surface methodology (RSM) performed the optimization of MAE and PLE. Next, the yield and the antioxidant activity results were maximized, and the lycopene content of the optimum MAE and PLE extracts was assessed by high-performance liquid chromatography (HPLC). Additionally, a fraction of raw material was oven dried as a comparison. The PLE extract exhibited the highest antioxidant activity, whereas the MAE extract showed the highest lycopene content (59.66 µg lycopene/g extract), which represents a 66.93% lycopene recovery compared to a standard technique with acetone. The remarkable results show that the non-conventional drying and extraction techniques were effective in valorizing this neglected material.

Recovery of bioactive components from avocado peels using microwave-assisted extraction

The avocado processing industry generates large amounts of avocado peels, which contain large amounts of high value-added compounds with antioxidant capabilities that have not yet been explored. Optimization of microwave-assisted extraction (MAE) of bioactive compounds from avocado peels with high antioxidant capacity was the objective of present work. Two experimental designs were implemented, using acetone 70% and ethanol at different concentrations, finding at 74.48 °C by 14.32 min and 66.37 °C by 0.97 min with 42.58% of ethanol as optimal conditions to obtain the highest antioxidant capacity, respectively. Optimized extracts with acetone and ethanol showed a high polyphenolic content (379.28 ± 19.35 and 354.43 ± 16.85 mg GAE/g dry extract, respectively); high antioxidant activity measured by DPPH (268.04 ± 25.11 and 233.85 ± 13.58 mgET/g dry extract, respectively); ABTS (895.19 ± 30.41 and 949.41 ± 7.42 mgET/g dry extract, respectively); ORAC (648.88 ± 28.66 and 692.06 ± 28.80 mgET/g dry extract, respectively), results reported for the first time. Fiber bonded phenolics compounds was extracted of MAE residues show a significant antioxidant activity. HPLC-MS analysis of optimized extracts showed the present of diverse phenolic acids, numerous procyanidins dimer A and B in different isomer shapes, catechin, epicatechin and perseitol.

Development of a colorless Centella asiatica (L.) Urb. extract using a natural deep eutectic solvent (NADES) and microwave-assisted extraction (MAE) optimized by response surface methodology.

This study outlines a green process for Centella asiatica (L.) Urb. (CA) extraction. Natural deep eutectic solvents (NADESs) and microwave-assisted extraction (MAE) were combined to provide a high bioactive compound yield and high antioxidant activity. Among the NADESs evaluated, the combination of acetylcholine chloride : malic acid : water (1 : 2 : 2): water (40 : 60) was the best for extraction. These conditions provide high madecassoside (MS) (21.7 mg g−1 dry weight) and asiaticoside (AS) (12.7 mg g−1 dry weight) yields, with greater than 80% (v/v) EtOH (13.3 mg g−1 MS and 7.80 mg g−1 AS). In addition, the extracts from this process showed higher antioxidant activity (IC50 = 0.26 mg mL−1) than the CA aqueous EtOH and water extracts. Moreover, the color of the extract products was less green than that of the extracts prepared using EtOH and aqueous EtOH as solvents, which are suitable for cosmeceutical products. Response surface methodology (RSM) was used for MAE optimization. The ANOVA data from the central composition design (CCD) of RSM were fitted with quadratic models yielding acceptable R2 (>0.93), adjusted R2 (>0.87), predicted R2 (>0.81), and nonsignificant lack of fit (p > 0.05) values. The quadratic model was validated using optimal conditions (30 s, power 300 W, and a liquid to solid ratio 20 mL g−1), and the model validation showed more than 80% accuracy in both MS and AS yields. This research presented an effective green process for CA extraction, which resulted in an environmentally friendly CA extract requiring little energy consumption and no organic solvents.