Extraction Of Phenolic Compounds Research Articles

Optimization of ultrasound-assisted extraction of phenolics from Cordia dichotoma leaves using response surface methodology

In this study, ultrasound-assisted extraction (UAE) was employed to extract phenolic compounds from Cordia dichotoma (C. Dichotoma) leaves. The extraction process was optimized using response surface methodology (RSM). The C. Dichotoma tree is found in tropical and subtropical areas and has medicinal properties. The obtained extracts were subjected to phytochemical screening using standard tests, antioxidant potential, and total phenolic content (TPC) of C. Dichotoma leaf extract by 2,2-diphenylpicrylhydrazyl assay and Folin-Ciocalteu assay respectively. The impact of process parameters like different solvents, solute-to-solvent ratio, ultrasonic power, and sonication time on TPC and antioxidant activity were studied. UAE offers a more rapid and efficient extraction process when compared to conventional extraction techniques such as Soxhlet extraction due to effective mass transfer. RSM models identified that ultrasonic power of 200 W and 30:1 (mL/g) solvent-to-solute ratio, using methanol, and a sonication time of 15 min are the optimal conditions for extraction of phenolics. FTIR analysis of methanolic extract confirmed the presence of phenolic functional groups. The compounds obtained from C. Dichotoma leaf extracts were identified by GCMS. UAE proves to be a promising technique for obtaining bioactive compounds with antioxidant potential from Cordia dichotoma leaves which can be potential applications in pharmaceutical, nutraceuticals, and functional food industries.

Green extraction of phenolic compounds from the by-product of purple araçá (Psidium myrtoides) with natural deep eutectic solvents assisted by ultrasound: Optimization, comparison, and bioactivity

The recovery of bioactive compounds is a promising approach for obtaining rich extracts from fruit by-products. This study investigated the influence of Natural Deep Eutectic Solvents (NADES) and Ultrasound-Assisted Extraction (UAE) on the phenolic content, antioxidant capacity, and in vitro antidiabetic activity of Psidium myrtoides by-product. Among eight NADES evaluated based on choline chloride, NADES ChCl:Gly (1:2) was selected for its efficiency in extracting total phenolic compounds (TPC) with high antioxidant capacity. The optimized conditions were 61 °C, a solid–liquid ratio of 100 mg 5 mL−1, and a 60-minute extraction time. ChCl:Gly exhibited superior TPC recovery (2.6-fold greater effectiveness) compared to the 60 % hydroethanolic solution. Twenty-six phenolic compounds were identified, including significant levels of catechin (336.48 mg g−1) and isoquercetin (26.09 mg g−1). Phenolic acids, such as p-anisic acid (5.47 mg g−1) and methoxyphenylacetic acid (0.23 mg g−1), were identified for the first time in the purple araçá by-product. The ChCl:Gly extract demonstrated the highest bioactivity, showcasing antioxidant and antidiabetic capacities. This study introduces an innovative and sustainable alternative for recovering phenolic compounds from fruit by-products, offering enhanced recovery efficiency and/or selectivity compared to organic solvents.

Effect of Ultrasound and Freeze‐Drying to Enhance the Extraction of Phenolic Compounds in Dragon Fruit Peels and Apply Them in Edible Starch‐Based Films

ABSTRACTIn this study, dragon fruit peels were subjected to different times (5, 10, 15, 20 and 25 min) of ultrasound pretreatment (4.870 W m−2/25°C) and then freeze‐drying (FD) (−56°C/48 h) to obtain powder particles, which underwent physical–chemical, functional and structural characterisation. Additionally, the extraction of total phenolic compound (TPC) was evaluated through ultrasound‐assisted kinetics and mechanical agitation. Finally, films based on black rice starch were developed with the addition (0.5, 1.5 and 2.5%) of dragon fruit peel powder particles, and their physical, barrier, antioxidant, structural and mechanical properties were evaluated. The results obtained showed that all particles had low water content (4.21%–6.58%) and high solubility (84.62%–88.73%) with a reduction in particle size (23.21–39.32 μm). In the extraction of TPC, the synergistic effect of the tested conditions increased efficiency, reaching 686.66 mg GAE/100 g for pretreated dragon fruit peel powder particles (25 min) in 180 min of extraction. Furthermore, the type ‘A’ crystallinity structure did not change significantly with pretreatment, but there was a reduction in peak area, reflecting on relative crystallinity, with a maximum decrease of 29.04%. The starch‐based films produced with 2.5% dragon fruit peel powder particles showed low solubility (28.72%) and low water vapour permeability (5.03 × 10−8 g mm s−1 m2 Pa), however, they contained higher levels of TPC (31.78 mg GAE/100 g film) and antioxidant activity (8.17 μmol TE/g film) that were easily migrated in aqueous medium. Furthermore, they also presented low values of tensile strength at break (3.41 MPa) and Young's modulus (4.18 MPa), as well as a high value of elongation at break (45.82%). Finally, our results highlight the potential of ultrasound as a pretreatment for FD of dragon fruit peels, paving the way for the development of rice starch‐based food packaging.

Eco-friendly and efficient extraction of phenolic compounds from Commiphora gileadensis bark using microwave-assisted extraction

Commiphora gileadensis (C. gileadensis) is a medicinal plant with a variety of biological activity; its bark has several therapeutic potentials, including the treatment of wounds, inflammatory diseases, and treating bacterial infections. This study utilized microwave-assisted extraction (MAE) to optimize the recovery and phenolic components of the ethanolic extracts of C. gileadensis bark. Different MAE process parameters (microwave power, irradiation time, sample/solvent ratio, extraction temperature, and solvent (ethanol) concentration) were studied for their impacts on the extraction process using One-Factor-At-a-Time (OFAT) method. The extracts were further characterized for the presence of different phytochemicals using Gas Chromatography-Mass Spectroscopy (FC-MS) and Fourier Transform Infrared Spectroscopy (FTIR) analyses. The experimental findings revealed that the maximum extraction yield, total phenolic content (TPC), and total flavonoid content (TFC) of the ethanolic extract of the of C. gileadensis bark using MAE process were 39.40 ± 0.47 w/w%, 166.41 ± 3.97 mg GAE/g d.w., and 52.83 ± 2.95 mg QE/g d.w., respectively. Furthermore, 30 phenolic constituents were discovered in the extract of C. gileadensis bark for the first time, and these compounds showed good in vitro antioxidant activity. Hence, MAE is a suitable technique for efficient and green extraction of different groups of phytochemicals of pharmaceutical importance from the bark of C. gileadensis.

Optimization of Ultrasonic-Assisted Extraction Condition for Total Phenolic Compounds from Citrus Hystrix Peel

This study aims to optimize the extraction conditions of Ultrasonic-Assisted Extraction (UAE) on the extraction of phenolic compound and antioxidant activity of Citrus Hystrix (C. Hystrix) peel. The experimental design was carried out using Face Centered Central Composite Design. A total of 20 sets of different combination experiment designs were generated from 3 parameters; temperature (30-50°C), time (20-40 min), and raw material to the solvent ratio (1:30-1:70). The highest yield of total phenolic compounds was 4.36 mg/g with the optimize extraction condition of , 30 min extraction time and 1:50 raw material to the solvent ratio. The result of this study indicates that the phenolic compounds extracted from C. Hystrix peel could have the potential to be used for pharmaceutical and food applications.

Extraction, characterization and optimization of phenolic compounds from Siam weed (Chromolaena odorata)

Extraction, characterization and optimization of phenolic compounds from Siam weed (Chromolaena odorata)

Formulation and Stability Assessment of Bakery Snacks Enriched with Encapsulated Phenolic Compounds from Lemnian Tomatoes and Pumpkin (Cucurbita moschata)

In recent years, the health-promoting properties of plant-derived compounds have garnered increasing scientific interest. Notably, tomatoes and pumpkins (Cucurbita moschata), renowned for their abundant phytochemicals and associated biological activities, have become focal points of research. This study investigated the extraction of phenolic compounds from tomatoes and pumpkins cultivated on Lemnos, an Aegean Island, aiming to enhance the nutritional profiles of food products. We established an extraction protocol for total phenolics and evaluated the antioxidant capacity using response surface methodology. Utilizing a central composite design, we optimized the extraction parameters, with time and ethanol concentration identified as critical factors (p < 0.05). The optimized extracts demonstrated substantial phenolic content (9.47 ± 0.08 and 4.52 ± 0.05 mg GAE/g for tomatoes and pumpkins, respectively) and antioxidant capabilities as determined by DPPH (7.65 ± 0.08 and 5.78 ± 0.05 μmol TE/g, respectively), ABTS (9.27 ± 0.02 and 3.95 ± 0.04 μmol TE/g, respectively), FRAP (5.25 ± 0.09 and 2.99 ± 0.03 μmol TE/g, respectively), and CUPRAC assays (2.3 ± 0.04 and 1.25 ± 0.03 μmol TE/g, respectively). Following extraction, the phenolic compounds were encapsulated using maltodextrin and subsequently freeze-dried, yielding high encapsulation efficiency. In alignment with a comprehensive strategy aimed at fostering functional snacks that enhance local economic and public health outcomes, vegetables sourced from local farms were employed to develop a savory cereal bar enriched with tomato extract and a sweet cookie infused with pumpkin extract.

Understanding microwave-assisted extraction of phenolic compounds from diverse food waste feedstocks

Microwave-assisted extraction (MAE) of natural antioxidants from food waste (FW) offers an economically appealing waste management strategy. However, MAE from mixed FW has received limited attention. We characterize five single waste streams (apple, coffee, olive, tomato, and potato peel waste) and study MAE of phenolic acids from select feedstocks and mixtures. This library of materials enables us to unravel the relationship of FW composition and physical properties with dielectric properties, heating, and extractive yields. Protein, ash, and moisture contents affect dielectric properties the most. Our study unveils the significance of moisture in free (> 20 wt%) and bound states (< 20 wt%) on FW dielectric properties, heating, and target acid yields (at least 33 % enhancement). Microwaves primarily heat the solvent (dimethylformamide) due to its superior dielectric properties compared to FW (dry and moist, single and mixtures) at ≤ 0.05 solid-to-liquid ratio (g/mL). High moisture content (> 20 wt%) provides higher phenolic yields at lower temperatures (< 100 °C) and shorter times (≤ 10 min) due to enhanced heat and mass transfer by microwaves. Further, our data indicates significant interactions between mixed FW components that drive 2–3x higher yields than those predicted from a simple additive model from single component results. Our work provides new insights for developing versatile MAE strategies to treat mixed FW feedstocks.

Green and efficient extraction of polyphenols from the leaves of Quercus dentata Thunb and in vitro antioxidant activities of polyphenol extract

The ultrasonic-coupled deep eutectic solvents method was firstly applied to extract phenolic compounds efficiently from the leaves of Quercus dentata Thunb. Five factors including type of deep eutectic solvent, water content, solid-liquid ratio, extraction time and extraction temperature were investigated based on total polyphenol content. The optimal extraction parameters were obtained through response surface methodology, that is, the deep eutectic solvent was composed of choline chloride and 1, 4-butanediol (molar ratio 1:2) with water content of 38%, the solid-liquid ratio was 1:30 g/mL, the extraction time was 31 min, the extraction temperature was 55 °C. At this condition, total polyphenol content reached the highest value of 78.56 ± 2.44 mg gallic acid/g. In addition, eleven phenolic compounds were identified by high performance liquid chromatography quadrupole/time-of flight mass spectrometry as flavonol glycosides. And then, the extraction showed good antioxidant activities in reducing transition metals (Fe3+, Cu2+, Mo6+) and scavenging free radicals (DPPH·, ABTS+·, O2−· and ·OH). Among them, the IC50 values of scavenging DPPH·, ABTS+·, O2−· and ·OH free radicals were 10.87 ± 0.25 μg mL−1, 8.04 ± 0.24 μg/mL, 149.47 ± 5.27 μg/mL and 131.73 ± 5.31 μg/mL, respectively. On the other hand, the extraction at the cellular level exerted its protective effect on PC12 cells by increasing the cell survival rate of H2O2-induced damaged cells, weakening the level of reactive oxygen species in damaged cells. Overall, this study provided a green and high-efficient strategy for extracting phenolic compounds with great antioxidant activities from Q. dentata leaves.

Green Synthesis of Chitosan-Coated Silver Nanoparticles (Ch-AgNPs): Harnessing Nature for Sustainable and Safe Nanomaterial Production

The production of silver nanoparticles (AgNPs) using green synthesis methods promotes the use of environmentally friendly materials and facilitates a more sustainable production process by reducing environmental impact. In addition, combining the metal nanoparticles with biopolymers are getting important to enhance the safety profiles of formulations to determine the biological activities. With this concept, AgNPs were synthesized by green synthesis method from Betula spp. tree branches as reported previously by us and in current study, synthesized AgNPs were coated by one of biopolymer. Herein, Chitosan was used as capping and stabilizing agent. Characterization of the biosynthesized silver nanoparticles (AgNPs) and Chitosan coated silver nanoparticles (Ch-AgNPs) were evaluated with various techniques. Through this analysis, it was elucidated that the phenolic compounds present in Betula extract and Chitosan played dual roles as both reducing and capping agents, facilitating the formation of Ch-AgNPs. Particular size analysis by dynamic light scattering (DLS) and scanning electron microscopy (SEM) indicated that the Ch-AgNPs ranged from 49 to 118 nm in size, with a narrow size distribution. X-Ray Differentiation (XRD) patterns confirmed the high crystallinity of the resulting particles. Fourier transform infrared (FTIR) analysis further supported these findings, revealing the involvement of phenolic compound extracts in both the formation and stabilization of AgNPs. Additionally, FTIR confirmed the surface modification of AgNPs by chitosan. The efficiency of surface modified Ch-AgNPs was compared with uncoated AgNPs for their antimicrobial activity, antiproliferative efficiency and biocompatibility. Cell culture studies demonstrated that AgNPs were less toxic to L929 cells while maintaining effective cytotoxicity against HT-29 cells. Moreover, surface modification with chitosan enhanced the toxicity of AgNPs against HT-29 cells Furthermore, the first synthesized and evaluated Ch-AgNPs with this study from Betula extract, exhibited potent antimicrobial activity against both Gram-positive and Gram-negative bacteria. Our findings indicate that novel synthesized Ch-AgNPs formula may present a biocompatible and safety approach for further anticancer and antimicrobial studies.

Preparation and Characterization of Natural Deep Eutectic Solvents (NADESs): Application in the Extraction of Phenolic Compounds from Araza Pulp (Eugenia stipitata).

Natural deep eutectic solvents (NADESs) of choline chloride (ChCl) and fructose, glucose, citric and malic acid with different water concentration were prepared and characterized. The pH ranged from 2.34 to 7.38. An increase in the intensity at 3300 cm-1 (FT-IR), by the interaction between the receptor and the hydrogen donor, occurred. The water content increased the intensity in the OH region without changing the vibrational mode. The same behavior occurred in Raman spectra. NADES without water showed a high density (1.234 to 1.375 g/mL) and viscosity (0.09991 to 0.46921 Pa·s). NADESs with 20% and 40% water were selected for extracting phenolic compounds from araza (Eugenia stipitata), using an ultrasonic system of bath, tip, and ethanol. Araza ethanol extract had a TPC (total phenolic compounds) of 325.19 mg GAE/g, and DPPH and ABTS of 12.00 and 291.31 µmolL-1 Trolox g-1. ChCl:citric acid (1:1) containing 40% water was the most efficient NADES in the tip ultrasound extraction: a TPC of 273.40 mg GAE/g; DPPH and ABTS of 31.55 and 204.9 µmolL-1 Trolox g-1; and an extraction yield of 84% related to ethanol. NADESs as solvents can be used directly by the food industry as a final product or ingredient, without purification, and proved to be versatile, with different properties.

Exploring phenolic compound extraction from marine seaweeds of south coast India: in vitro antioxidant and antimicrobial evaluation

Exploring phenolic compound extraction from marine seaweeds of south coast India: in vitro antioxidant and antimicrobial evaluation

Evaluation of the solvent effect on the extraction and antioxidant activity of phenolic compounds from the nettle (Urtica dioica L.) seeds: application of PCA and regression analyses

Evaluation of the solvent effect on the extraction and antioxidant activity of phenolic compounds from the nettle (Urtica dioica L.) seeds: application of PCA and regression analyses

Comparative rheology and antioxidant potential of high-methoxyl sugar acid gels of unrefined powder and acid-extracted pectin from two hawthorn (Crataegus pinnatifida) fruit cultivars

Hawthorn fruits (Crataegus pinnatifida) present high content of high-methoxyl pectin, able to gel under high-sugar acidic conditions. In this work, the proximate and phytochemical composition of two cultivars of hawthorn fruit and the gelling ability of their unrefined (not further processed) dried powders and their extracted pectins were evaluated and systematically compared with citrus pectins (CP1 and CP2). Mianqiu (MI), a less known cultivar, showed two-fold higher pectin content and titratable acidity than Dajinxing (DA), one of the most common cultivars. DA showed higher starch, insoluble dietary fiber, pasting viscosity and total and extractable (EPP) phenolic compounds. EPP content was almost two-fold higher in DA than MI, resulting in stronger antioxidant properties. All high-methoxyl sugar acid gels exhibited a predominantly elastic response. MI resulted in hawthorn-powder gels with higher elastic modulus (G′) after gel-making (initially stronger gels), and lower G′ increase during storage (hardening) than DA. Citrus pectins (CP2 > CP1) showed higher gel-strength and faster gelling ability than hawthorn pectin gels (DA > MI) based on the lower G’ and lack of gel formation after 90 min of cooling in hawthorn pectin-based gels. The gelation results were closely linked to the starch-to-pectin ratio, purity, and degree of methyl esterification.

Antityrosinase activity and LC-MS/MS analysis of optimized ultrasound-assisted condition extracts and fractions from strawberry tree (Arbutus unedo L.).

Investigation of utilization possibilities of natural sources has been an important area for research. Tyrosinase inhibitory activity plays a key role in food and medicine industry. Strawberry tree (Arbutus unedo), a widely distributed plant among Mediterranean countries, possess fruits and leaves with rich bioactive phytochemicals, especially polyphenolic compounds. In this study, we aimed to investigate the antityrosinase activity of the fruit and leaf extracts of the plant, and to determine the phenolic compounds that contribute to the antityrosinase activity. In this regard, we evaluated the effect of solvent composition on the extraction of phenolic compounds from A. unedo and on its antityrosinase activity using a simplex centroid design approach, and used chromatographic and LC-MS/MS techniques. The leaf extracts prepared using EtOH:water (50:50) provided higher TPC (456.39 mg GAE/g extract) and acetone:EtOH:water (33:33:33) provided higher TFC (56.15 mg QE/g extract) values than of fruit extracts. LC-MS/MS analysis revealed 23 phenolic/flavonoid compounds in leaf extracts (L1-8), and major metabolites were detected as quercitrin, quinic acid, catechin, tannic acid, isoquercitrin, gallic acid, and ellagic acid. Among the leaf extracts, L3 (aceton:water, 50:50) exhibited 72.01% tyrosinase inhibition at 500 μg/mL. After fractionation studies guided by antityrosinase activity, its subfraction L3-Fr2 exhibited 40.06% inhibition at 50 μg/mL concentration (IC50: 146 ± 7.75 μg/mL), and catechin (113.19 mg/g), tannic acid (53.14 mg/g), ellagic acid (22.14 mg/g), gallic acid (10.27 mg/g), and epicatechin gallate (8.65 mg/g) were determined as major metabolites. Its subfraction L3-Fr2-sub7 exhibited better antityrosinase activity (IC50: 206.23 ± 9.87 μg/mL), and quantitative analysis results revealed the presence of tannic acid (127.40 mg/g), gallic acid (13.96 mg/g), ellagic acid (7.66 mg/g), quercetin-3-O-glucuronide (5.06 mg/g), and quinic acid (3.2 mg/g) as major metabolites, and correlation analysis showed that ellagic acid and quinic acid were positively correlated with antityrosinase activity.

Extraction of phenolic compounds from lucuma (Pouteria lucuma) seeds with natural deep eutectic solvents: modelling using response surface methodology and artificial neural networks

The present study aimed to extract polyphenolic compounds from lucuma (Pouteria lucuma) seeds using natural deep eutectic solvents (NADES) as a green, efficient, and environmentally friendly extraction. This was optimized by using the Response Surface Method (RSM) and comparing its predictive capacity with Artificial Neural Networks (ANN) and Convolutional Neural Networks (CNN). Four NADES were prepared by mixing lactic acid (LA) with each of the following reagents: sodium acetate (SA), urea (U), glucose (G), and ammonium acetate (AA), separately. The yield of total phenolic compounds (TPC) obtained from lucuma seeds with each NADES was measured as an optimization criterion with the Box-Benhken design. The following factors were evaluated: time, temperature, and the lucuma seed flour (LSF): NADES ratio. The response variables were TPC and antioxidant activity. The LA-AA extract was selected because it exhibited the highest TPC value and was analyzed by UHPLC–MS (Ultra-performance Liquid Chromatography-Mass Spectrometry). From the RSM, the optimal extraction parameters were 80 min, 52°C, and LSF: NADES ratio of 8:100 (w/v), obtaining a TPC value of 3601.51 ± 0.51 mg GAE/100 g LFS. UHPLC–MS analysis evidenced the formation of epigallocatechin isomers from epigallocatechin gallate. The predictive ability of ANNs compared to RSM was demonstrated.

Untargeted Metabolomics Analysis Based on LC-QTOF-MS to Investigate the Phenolic Composition of Red and White Wines Elaborated from Sonicated Grapes.

Ultrasounds are considered an emerging technology in the wine industry. Concretely, in 2019, the International Organization of Vine and Wine (OIV) officially approved their use for the treatment of crushed grapes to increase the level of phenolic compound extraction. The main objective of this study was to validate an untargeted metabolomics approach as an analytical tool for identifying novel markers associated with sonication. To do so, the influence of a sonication treatment on the metabolic profile was studied in four typically commercial varietal wines, i.e., two red wines from 'Syrah' and 'Cabernet Sauvignon' grapes and two white wines from 'Macabeo' and 'Airén' grapes. A robust classification and prediction model was created employing supervised techniques such as partial least-squares discriminant analysis (PLS-DA). The findings indicated that the grapes subjected to high-power ultrasound conditions experienced cell wall disruption due to the cavitation phenomenon, resulting in significant changes in various phenolic compounds (including hydroxycinnamic acids and flavonoids) present in these wines compared to wines from non-sonicated grapes. Additionally, new metabolites were tentatively identified through untargeted metabolomics techniques. This study represents the successful application of the untargeted metabolomics approach employing a UHPLC-QTOF system to discern how grape sonication affects bioactive secondary metabolites in wines.

Exploring Phenolic Compounds Extraction from Saffron (C. sativus) Floral By-Products Using Ultrasound-Assisted Extraction, Deep Eutectic Solvent Extraction, and Subcritical Water Extraction.

Saffron (Crocus sativus) floral by-products are a source of phenolic compounds that can be recovered and used in the nutraceutical, pharmaceutical, or cosmetic industries. This study aimed to evaluate the phenolic compounds' extraction using green extraction techniques (GETs) in saffron floral by-products and to explore the influence of selected extraction techniques on the phytochemical composition of the extracts. Specifically, ultrasound-assisted extraction (UAE), subcritical water extraction (SWE), and deep eutectic solvents extraction (DESE) were used. Phenolic compounds were identified with (HR) LC-ESI-QTOF MS/MS analysis, and the quantitative analysis was performed with HPLC-PDA. Concerning the extraction techniques, UAE showed the highest amount for both anthocyanins and flavonoids with 50:50% v/v ethanol/water as solvent (93.43 ± 4.67 mg/g of dry plant, dp). Among SWE, extraction with 96% ethanol and t = 125 °C gave the best quantitative results. The 16 different solvent mixtures used for the DESE showed the highest amount of flavonoids (110.95 ± 5.55-73.25 ± 3.66 mg/g dp), while anthocyanins were better extracted with choline chloride:butane-1,4-diol (16.0 ± 0.80 mg/g dp). Consequently, GETs can be employed to extract the bioactive compounds from saffron floral by-products, implementing recycling and reduction of waste and fitting into the broader circular economy discussion.

Advanced NADES-based extraction processes for the recovery of phenolic compounds from Hass avocado residues: A sustainable valorization strategy

Natural Deep Eutectic Solvents (NADES) are eco-friendly solvents with considerable potential for extracting bioactive compounds. In this study, we aimed to extract phenolic compounds from Hass avocado residues (epicarp and seed) using NADES in combination with ultrasound-assisted extraction (UAE) and pressurized liquid extraction (PLE) as advanced processes. Ten eutectic mixtures, consisting of choline chloride (ChCl) or betaine as hydrogen bond acceptors (HBA), as well as fructose (Fru), glucose, lactic acid (Lac), citric acid, or glycerol as hydrogen bond donors (HBD), were prepared through stirring and heating. The estimated values for total phenol content (TPC), proanthocyanidin content (PAC), monomeric anthocyanin content (MAC), and antioxidant capacity of the extracts demonstrated a noticeable influence of these solvents. The PLE process significantly enhanced the extraction of phenolic compounds from the epicarp, as evidenced by TPC (185 ± 9 mg gallic acid equivalent/g dry sample) and PAC (77.8 ± 6 mg proanthocyanidin B2/g dry sample) values. Phytochemical characterization conducted via HPLC-QTOF-MS/MS revealed the great extraction capacity of ChCl:Fru and ChCl:Lac, and the improvement of extraction efficiency through PLE. The results suggest that employing these innovative solvents along with advanced extraction processes, especially under high pressures, provides a sustainable approach to recover extracts with high content of phenolic compounds from Hass avocado agro-industrial waste, thus enabling their valorization.

Extraction of phenolic compounds with antioxidant activity from olive pomace using natural deep eutectic solvents: modelling and optimization by response surface methodology

This work explored the use of natural deep eutectic solvents (NADES) for extracting phenolic compounds with antioxidant activity from Uruguayan olive pomace (OP), a by-product of olive oil mills. Among nine NADES tested, lactic acid-glucose (La-Gc) was the most effective solvent for phenolic compound extraction. Further investigation focused on optimizing the extraction process using La-Gc. Response surface methodology was employed to analyze the impact of extraction temperature, water content in NADES and solid–liquid ratio on total phenols content (TPC) and antioxidant activity (FRAP and DPPH assays). Temperature and solid–liquid ratio greatly influenced TPC and antioxidant activity, while water content in NADES only showed significant influence on antioxidant activity. The optimum extraction conditions that maximized TPC and antioxidant activity were 80 ∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${}^{\\circ }\ ext {C}$$\\end{document}, 68% (w/w) of water in NADES and solid–liquid ratio of 0.014 g/mL, showing a TPC of 15.56 mg GAE/g db, FRAP of 178.14 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}mol FSE/g db and DPPH of 72.75 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mu$$\\end{document}mol TRE/g db, with hydroxytyrosol content of 1.24 mg/g db. These values were significantly higher than those of extracts obtained from conventional solvents under identical extraction conditions. These results highlight the suitability of the present extraction method using La-Gc as solvent to obtain phenolic compounds with antioxidant activity from OP.