Yield Of Phenolic Compounds Research Articles

HYDROGENATION OF ABIES WOOD ETHANOL-LIGNIN WITH HYDROGEN IN ETHANOL MEDIUM IN THE PRESENCE OF NiCuMo/SiO2 CATALYST

In the development of studies on the catalytic conversion of lignin to liquid hydrocarbons, the effect of the bifunctional NiCuMo/SiO2 catalyst on the yield and composition of abies wood ethanol-lignin hydrogenation products in ethanol medium at a temperature of 250 °C was established. According to thermogravimetric analysis data the main thermal decomposition of abies wood ethanol-lignin occurs in the range from 260 to 600 °C with the maximum rate of degradation (3.9%/min) at 398.3 °C. The catalyst increases the yield of liquid products from 75.0 to 88.0 wt%, and reduces the yield of solid residue from 14.0 to 0.6 wt%. The total yield of phenolic compounds of non-catalytic hydrogenation does not exceed 4.5 wt%. The bifunctional nickel-containing catalyst increases by two times (up to 9.2 wt.%) the yield of liquid phenolic products, among which dimers and 4-propyl guaiacol predominate. The molecular weight distribution of the liquid products of the catalytic hydrogenation of abies ethanol-lignin shifts to the low molecular weight region due to the increase in the content of dimeric and monomeric phenolic compounds in liquid products. The obtained methoxyphenols can be used as components of epoxy resins, polycarbonates, fuel additives, and in other areas.

Ultrasonic-Assisted Extraction of Phenolic Compounds, Flavonoids, and Antioxidants from Dill (Anethum graveolens L.).

This study evaluated the effect of ultrasonic-assisted extraction (UAE) on the isolation of phenolic compounds, flavonoids, and antioxidants from dill. UAE improved the extraction yields of total phenolic compounds and total flavonoid content as well as increased the antioxidant activities of all dill extracts. The optimum UAE condition to obtain highest total phenolic compounds, total flavonoid content, and antioxidant activities was 50% ethanol for 30 min giving 135.88 ± 3.23 mg gallic acid equivalent/g extract and 229.53 ± 4.97 mg rutin equivalent/g extract, respectively. Lowest IC50 values against 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals were 0.034 ± 0.00 mg/mL and 0.12 ± 0.00 mg/mL, respectively. Results indicated the capability of UAE in extracting biologically active compounds from dill as a prospective functional material.

High-Yield Recovery of Antioxidant Compounds from Bambusa chungii Culms Using Pressurized Hot Water Extraction.

A large amount of waste from Bambusa chungii culms is generated from the bamboo pulping industry, causing disposal problems. Nevertheless, bamboo culms are a suitable source of functional ingredients, such as antioxidant compounds. However, because of the high compactness and tightness in their material structure, obtaining phytochemicals from bamboo culms using conventional organic solvent extraction methods can be inefficient. In this research, we developed a pressurized hot water extraction (PHWE) method to recover 19 target phenolic compounds from Bambusa chungii culms. The extracted compounds were determined by ultra-high performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-QTOF-MS). The antioxidant potential of the extracts was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) assays. We investigated the effects of temperature, extraction time, and the material-to-liquid ratio on PHWE, and these parameters were optimized with a Box-Behnken design experiment and response surface tool. The optimal extraction condition was found at 170 °C, with a 1:30 g/mL material-to-liquid ratio and a 14 min extraction time. Following these optimal parameters, the total yield of target phenolic compounds (TYPC) reached 3.85 mg/g of raw material, and the half-maximal inhibitory concentrations (IC50) for the DPPH and ABTS tests were 94.7 mg/L and 21.88 mg/L, respectively. The FRAP value was 1.23 μmol FSE/mg of dried extract. A strong correlation between TYPC and the antioxidant activity of the extract was confirmed. The TYPC and antioxidant capacity of the optimal PHWE extract of the Bambusa chungii culms were both considerably higher than those of extracts obtained from conventional solvent extractions. These results indicated that PHWE is an excellent green technique for recovering phenolic compounds from bamboo culms, and the PHWE extracts of Bambusa chungii culms may be a good source of natural antioxidants.

Optimization of solvent extraction conditions of bioactive compound from wood apple (Limonia acidissima L.) fruit using ultrasonic assisted extraction

AbstractUltrasonic assisted extraction is a novel technique that can be applied to obtain bioactive compounds from plants with great efficiency. The aim of this study was to optimize the phenolic extraction efficiency and DPPHsc activity from the wood apple (Limonia acidissima L.) fruit. Phenols were extracted using different polar solvents, namely methanol and acetone. The conditions of extraction with the ultrasonic method using response surface methodology central composite design (CCD) and the variables include the solvent concentration of methanol and acetone (50%–100%), ultrasonic temperature (30–50°C), sonication duration (20–40 min), and ultrasonic frequency (25–45 kHz). Optimum extraction conditions were determined as follows: 61.5% of solvent concentration and extraction temperature of 50°C for 40 min of extraction time at 25 kHz ultrasonic frequency for methanol. For these extraction conditions in the case of methanol extract, the phenolic yield, total phenolic content, and DPPHsc were found to be 25.81%, 224.36 μg GAE/g, and 93.49%, respectively. For the acetone extract, optimum extraction conditions were as follows: 52.68% solvent concentration, 47.89°C temperature, 39.8 min, and 0.73 kHz ultrasonic frequency. The results obtained under these optimized conditions were 23.78% yield of phenolic extract, 290.76 μg GAE/g TPC, and 91.28% DPPHsc, for acetone. The result demonstrated that the highest phenolic efficiency, phenolic content, and DPPHsc were observed for the methanolic solvent extract. SEM images of ultrasonicated powder samples showed that sonication results in cell rupturing and thus increasing the mass transfer for bioactive compounds. Furthermore, the results of ultra‐high‐performance liquid chromatography (UHPLC) analysis of phenolic compounds from the methanolic extract of wood apple fruit pulp revealed the presence of gallic acid, catechin, caffeic acid, syringic acid, vanillic acid, and quercetin in a magnificent amount.Novelty impact statementTraditionally, solvent extraction techniques have been done in wood apple fruit; however, in this work, we add an advanced technology, the ultrasonic assisted extraction, which improves the extraction yield and efficiency of phenolic compounds using different organic solvents. After that study planned, SEM analysis shows a structural description which is evident that how this advanced technology shows a structural disruption that enhances extraction efficiency. After that study planned for chromatography by UHPLC that highlights the essential bioactive or phenolic compound obtained in the ultrasonic extract.

The Efficacy of Phenolic Compound Extraction from Potato Peel Waste

As an agroindustrial waste product, potato peels contain valuable phenolic compounds that can be extracted before they are sent to the landfill. Based on previous work, this study focused on determining the efficacies of phenolic compound extraction from potato peels using conventional shaking extraction (CSE) and both direct ultrasound-assisted extraction (DUAE), and indirect ultrasound-assisted extraction (IUAE). The yield curve associated with each extraction method was measured and characterized. The maximum yield of phenolic compounds and its dependence on processing parameters were evaluated. The applicability of the Peleg model for describing the yield curve was evaluated. Based on the Peleg model, a recovery ratio was defined to calculate its corresponding extraction rate. This extraction rate, combined with the yield, can be used for describing the efficacy of an extraction method. Our results indicate that the ultrasound-assisted extraction methods were capable of extracting phenolic compounds at a given recovery ratio one or two orders of magnitude faster than the CSE method. Models described in the article are expected to be useful in evaluating the extraction efficacy of valuable compounds from various agricultural or agroindustrial waste.

Phenol-rich bio-oil from pyrolysis of palm kernel shell and its isolated lignin

Phenol and phenolic compounds are the important chemicals for several industries. To reduce the dependence on the petroleum-based production, lignocellulosic biomass becomes the promising resource. Palm kernel shell and its real isolated lignin were comparatively studied for the potential on the production of phenol and phenolic compounds via the pyrolysis process. Both samples were subjected to various chemical and thermal analyses to compare their chemical structures and thermal behavior. The pyrolysis process of palm kernel shell and its lignin was performed with a fixed-bed reactor to generate bio-oil with a high fraction of phenol and phenolic compounds. The extraction process could affect the structure of lignin and the pyrolysis behavior of the lignin. Pyrolysis experiments showed that the isolated lignin gave a higher yield of bio-oil than the palm kernel shell and about twice the total fraction of phenol and phenolic compounds. Phenol production from palm kernel shell was highest at a pyrolysis temperature of 500 °C, while yields of other phenolic compounds were highest at 400 °C. Including phenol, H-type phenolic compounds were the main product from both palm kernel shell and its isolated lignin. C-type phenolic compounds were found in significant quantities in the bio-oil from lignin. The total fraction of phenol and other phenolic compounds from the lignin bio-oil was up to 78 % and higher than that from the palm kernel shell bio-oil. • Isolated lignin of PKS was studied for phenol and phenolic production. • Highest production of phenol was from the pyrolysis of PKS at 500 °C. • Lignin generated more total phenol and phenolic compounds than PKS. • Lignin gave 78 % of phenol and phenolic compounds in bio-oil.

Quantification of microstructural changes in artichoke by-products by image analysis after high-power ultrasound-assisted extraction of bioactive compounds

Image analysis of optical and scanning electron micrographs was successfully used to quantify the microstructural effect of ultrasound application (at 200 and 335 W/L) in artichoke stem samples during the extraction of phenolic compounds and chlorogenic acid. Three temperatures were evaluated (25, 40, and 60 °C) and ultrasound-assisted extraction was compared with mechanical assisted extraction (100 rpm). The low extraction yields of phenolic compounds and chlorogenic acid at 25 °C with mechanical agitation (3.9% and 0.9%) increased up to 96.7% and 78.5%, respectively, at 60 °C and 335 W/L ultrasonic power density. Breakages in plant tissue increased from 4.3% after extraction by mechanical agitation at 25 °C to 10.7% and 16.7% at 25 °C when US at 200 W/L and 335 W/L were applied, respectively. The combined effect of temperature and ultrasound during extraction promoted cell shrinkage, and thus, an increase in cell number per area, reaching the highest increase (36%) when extraction was performed at 60 °C and 335 W/L. The intensified ultrasonic-assisted extraction process affected the microstructure of the solid, with the magnitude of the effects depending on both the extraction temperature and the ultrasonic power density, which explains the increase in extraction yields.

Hyphenated Extraction of Valuable Compounds from Aesculus carnea: Ultrasound Extraction with Pulsed Electric Field Pretreatment

Wood-related procedures, such as lumberjacking and pruning, inevitably result in big piles of leaves, which are considered a major by-product. Extracting valuable compounds from natural by-products is an ongoing trend. In this work, the use of Pulsed Electric Field (PEF) was evaluated as a pretreatment step, prior to the ultrasound-assisted extraction of phenolic compounds from Aesculus carnea leaves. In addition, various solvent systems were examined, as well as the time of pretreatment with PEF. According to the results, up to 33% more phenolic compounds can be extracted, under optimum conditions (30% ethanol in water as solvent and PEF pretreatment for 30 min, compared to the same solvent, without PEF). Moreover, PEF treatment time was not (i.e., 30 and 60 min) and no differences were recorded, suggesting that a lower treatment time can yield the same extraction of phenolic compounds. As such, the use of PEF is highly recommended in combination with ultrasound extraction, to maximize the yield of phenolic compounds extracted from the leaves of Aesculus carnea.

Pressurized hot water extraction of crude polysaccharides, β-glucan, and phenolic compounds from dried gray oyster mushroom

This study aimed to investigate the effects of temperature (100 °C–140 °C), pressure (0.4–1.0 MPa), and extraction time (20–60 min) on the extraction yield of crude polysaccharides, β-glucan, and total phenolic compounds with pressurized hot water extraction of gray oyster mushrooms (Pleurotus sajor-caju (Fr.) Singer). The extraction conditions were optimized by maximizing all responses, using a central composite design (CCD)-based response surface methodology. Temperature mainly affected the increase in the extracted yield and phenolic content. However, exceeded temperature and extraction time negatively affected the β-glucan yield. The optimal extraction conditions were at 140 °C, 0.92 MPa, and 40 min with a corresponding extraction yield of 3.20 ± 0.17 g/100 g, as well as β-glucan and total phenolic contents of 43.84 ± 3.86 mg/100 g and 8.49 ± 0.66 mg gallic acid equivalent/100 g dried extract, respectively. The antioxidant activities of extracts were estimated by in vitro biological assays. The SC50 values of DPPH, NO, and ABTS assays were 1.66 ± 0.02, 1.50 ± 0.19, and 6.94 ± 1.04 mg/mL, respectively. This work demonstrates an alternative approach to valorize over-produced mushrooms.

Enhanced production of amylase, pyruvate and phenolic compounds from glucose by light-driven Aspergillus niger-CuS nanobiohybrids.

The demand for value-added compounds such as amylase, pyruvate and phenolic compounds produced by biological methods has prompted the rapid development of advanced technologies for their enhanced production. Nanobiohybrids (NBs) make use of both the microbial properties of whole-cell microorganisms and the light-harvesting efficiency of semiconductors. Photosynthetic NBs were constructed that link the biosynthetic pathways of Aspergillus niger with CuS nanoparticles. In this work, NB formation was confirmed by negative values of the interaction energy, i.e.,2.31 × 108 to -5.52 × 108 kJ mol-1 for CuS-Che NBs, whereas for CuS-Bio NBs the values were -2.31 × 108 to -4.62 × 108 kJ mol-1 for CuS-Bio NBs with spherical nanoparticle interaction. For CuS-Bio NBs with nanorod interaction, it ranged from -2.3 × 107 to -3.47 × 107 kJ mol-1 . Further, the morphological changes observed by scanning electron microscopy showed the presence of the elements Cu and S in the energy-dispersive X-ray spectra and the presence of CuS bonds in Fourier transform infrared spectroscopy indicate NB formation. In addition, the quenching effect in photoluminescence studies confirmed NB formation. Production yields of amylase, phenolic compounds and pyruvate amounted to 11.2 μmol L-1, 52.5 μmol L-1 and 28 nmol μL-1, respectively, in A. niger-CuS Bio NBs on the third day of incubation in the bioreactor. Moreover, A niger cells-CuS Bio NBs had amino acids and lipid yields of 6.2 mg mL-1 and 26.5 mg L-1, respectively. Furthermore, probable mechanisms for the enhanced production of amylase, pyruvate and phenolic compounds are proposed. Aspergillus niger-CuS NBs were used for the production of the amylase enzyme and value-added compounds such as pyruvate and phenolic compounds. Aspergillus niger-CuS Bio NBs showed a greater efficiency compared to A. niger-CuS Che NBs as the biologically produced CuS nanoparticles had a higher compatibility with A. niger cells. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Stabilization of peppermint polyphenols within crystalline sucrose matrix: Fortification of gummy candy as a food model system

In this study, the phenolic extract of peppermint was loaded within a sucrose matrix at three concentrations (3%, 5%, and 10%) by the co-crystallization process. Physical properties (flowability, color indices, density, solubility, and hygroscopicity), total phenolic content (TPC), and antioxidant properties (DPPH*, ABTS+, OH* radicals scavenging activity, and reducing power) and morphology of the samples were evaluated. The co-crystallized powders (Co-10%) were substituted with sucrose at different levels (25%, 50%, 75%, and 100%) in the gummy candy formulation. In this study, the encapsulation yield (EY) of phenolic compounds was about 82%. It was identified that increasing the concentration of the loaded within a sucrose matrix caused chroma and b* values of the samples to significantly increase. The powder containing 10% peppermint extract with the highest loading capacity (1.85 mg GAE/g) shows the highest antioxidant capacity in DPPH inhibitory (64.07%), ABTS+ (52.9%), TEAC (1.38 mM), OH radical scavenging activity (77.65), and reducing power (0.92 Abs700). Also, scanning electron microscopy images showed the clusters with porous structures in co-crystallized powders. The differential scanning calorimeter results of co-crystallized peppermint extract showed that the melting point slightly increased to a higher temperature. The gummy candy formulated using 75% co-crystallized powders had the highest score in terms of color, texture, and taste. In general, the co-crystallized powders replace with sucrose in various confectionery products, fruit desserts, jams, and functional foods. Novelty impact statement The co-crystallization is an effective method for encapsulating of the bioactive compounds. The gummy candy formulated using co-crystallized powders had the highest score in terms of color, texture, and taste. Color indices, texture, antioxidant activity, and sensory characteristics of gummy candies were affected by the concentration of active compounds.

Maximising Recovery of Bioactive Compounds from Coffee Pulp Waste Using Microwave-assisted Extraction

Coffee pulp is a major by-product generated from coffee bean production and is generally known as waste. This study employed response surface methodology (RSM) with Box Behnken Design (BBD) to determine the impact of extraction parameters and optimise the conditions for recovery of total phenolics, flavonoids, chlorogenic acid, and caffeine from coffee pulp using a commercial microwave-assisted extraction system (MAE) for further applications. The results showed that sample to solvent ratio and ethanol concentration significantly affected the recovery yields of bioactive compounds and antioxidant capacity. There were significant interactive effects between the radiation time and sample to solvent ratio, but no significant interactive impacts between radiation time and ethanol concentration, radiation time and power, sample to solvent ratio and power, and ethanol concentration and power on recovery of bioactive compounds and antioxidant capacity of the coffee pulp extract. The optimal conditions were found to be radiation time of 85 min, sample to solvent ratio of 1:100 g/100 ml, 42.5 % (v/v) aqueous ethanol solution, and machine power of 1000 W. Under these conditions, extraction yields of total phenolic compounds, flavonoids, chlorogenic acid, and caffeine were 38.68, 27.00, 6.95, and 5.47 (mg/g DW), respectively. The extract also had high antioxidant capacities, with values measured by ABTS, DPPH, and FRAP assays as 87.95, 9.3, 65.31 (mg TE/g DW), respectively. These conditions are recommended for the recovery of bioactive compounds from coffee pulp for further applications.

Investigation of phenolic, flavonoid, and antioxidant recovery and solubility from Roselle using supercritical carbon dioxide: Experiment and modeling

The purpose of this work was to determine the optimal conditions for recovering high yields of total phenolic compounds (TPC), total flavonoid compounds (TFC), and antioxidant activity (AA) from roselle (Hibiscus sabdariffa) by employing supercritical carbon dioxide (ScCO2). The solubility of yield, phenolic, and flavonoid in ScCO2 was estimated using solubility models. Pressure (10 to 20 MPa), temperature (40 to 60°C), and flow rate (3 to 5 ml/min) were used as factors in this investigation. According to the response surface methodology (RSM), the optimal conditions were 20 MPa, 40°C, and 4.875 ml/min, yielding 14.11%, 935.48 mgGAE/L TPC, 812.16 mgQUE/L TFC, and 98.59% antioxidant activity, respectively. With 5.29%, 1.28%, and 1.34% of average absolute relative deviation (AARD), the Putra model provided the best connection to the yield extract, phenolic, and flavonoid solubility. The use of RSM and modeling was effective in attaining a high production and concentration of phenolic compounds. Practical applications Roselle (Hibiscus sabdariffa) comprises several beneficial components, including phenolic, flavonoid, and antioxidant substances. It is used to treat pyrexia, liver damage, hypertension, and leukemia, among other conditions. Toxic and conventional solvents, on the other hand, have often been utilized to recover these valuable compounds. To alleviate these disadvantages, the important chemicals in roselle are extracted using supercritical carbon dioxide (ScCO2). The solubility behavior of oil yield, phenolic, and flavonoid compounds was determined in this work using a semi-empirical model. The data indicate that an endothermic process occurred to enhance the solubility of yield extract and the exothermic process is suitable for the phenolic and flavonoid recovery.

Optimization of Pulsed Electric Fields-Assisted Extraction of Phenolic Compounds From White Grape Pomace Using Response Surface Methodology

This study was focused on the optimization of the pulsed electric fields (PEF)-assisted extraction process using central composite design for response surface methodology from response surface methodology (RSM) with the aim to sustainably intensify the extractability of phenolic compounds from white grape pomace. The cell disintegration index (Zp) was used as response variable to identify the optimal PEF pre-treatment conditions of grape pomace in terms of field strength (E = 0.5–5 kV/cm) and energy input (WT = 1–20 kJ/kg), to be applied prior to the subsequent solid-liquid extraction (SLE) process. for both untreated and PEF-treated samples SLE process was optimized to determine the most effective combination of extraction temperature (20–50°C), extraction time (30–300 min), and solvent concentration (0–100% ethanol in water). Total phenolic content (TPC), flavonoid content (FC), and antioxidant activity (FRAP) of the obtained extracts were determined. The extracted compounds from untreated and PEF-treated samples at the optimal conditions were analyzed via HPLC-PDA analysis. Results revealed that, at a fixed extraction temperature (50°C), the application of PEF at optimal processing conditions (E = 3.8 kV/cm, WT = 10 kJ/kg) prior to SLE has the potential to reduce the solvent consumption (3–12%) and shorten the extraction time (23–103 min) to obtain the same recovery yield of phenolic compounds. Under optimized conditions, the extracts derived from PEF-treated samples showed significantly higher TPC (8%), FC (31%), and FRAP (36%) values, as compared to the control extraction. HPLC analyses revealed that epicatechin, p-coumaric acid, and quercetin were among the main phenolic compounds extracted, and no degradation phenomena occurred due to PEF application.

Effect of steam explosion pretreatment on the composition and bioactive characteristic of phenolic compounds in Chrysanthemum morifolium Ramat cv. Hangbaiju powder with various sieve fractions.

Steam explosion (SE) pretreatment is an efficient technique to promote the fiber degradation and disrupt materials' cell wall. In this study, the effect of SE pretreatment on the changes in phenolic profile, and the in vitro digestion property of a Chinese indigenous herb “Hangbaiju” (HBJ) powder with various sieve fractions (150‐, 180‐, 250‐, 425‐, and 850‐μm sieves) were studied. After SE pretreatment, the morphological structure, color attributes, and composition of phenolic compounds were altered significantly (p < .05). The composition and content of phenolic compounds were strongly correlated with particle sizes. The higher extraction yield of phenolic compounds was reached in the intermediate sieve fraction (ca. 250‐μm sieves). During in vitro digestion, the changes in phenolic compounds were significant due to the transition from an acidic to the alkaline environment (p < .05). Based on the multivariate statistical analysis, apigenin‐7‐O‐glucoside, luteolin‐7‐O‐glucoside, and linarin, were viewed as the characteristic compounds among various samples. The results highlighted that the phytochemical properties mainly including the composition of phenolic compounds, and in vitro digestion properties of HBJ powder with intermediate sieve fraction could be improved after SE pretreatment.

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Effect of Different Extraction Methods and Geographical Origins on the Total Phenolic Yield, Composition, and Antimicrobial Activity of Sugarcane Bagasse Extracts.

Several parameters, including particle size, solvent, temperature, and extraction method, affect phenolic compounds' extraction yield from a plant matrix. Considering the wide availability of sugarcane bagasse (SCB), this study analyzed the effect of different extraction methods and geographical origins on the yield, quality, and antimicrobial activity of phenolic compounds from SCB extracts. Samples from three geographical locations (Veracruz, Mexico; Santa Rosa, Texas, USA; and St. Mary, Louisiana, USA) were analyzed. Extraction was performed using an orbital shaker or ultrasonic bath at various times at a fixed temperature of 50°C, with 90% ethanol or methanol. The highest yield (5.91 mg GAE) was obtained using an orbital shaker for 24 h with 90% methanol as the solvent. HPLC-MS identified desferrioxamine b, baicalein, madecassic acid, and podototarin at different concentrations in all three SCB samples. The antimicrobial activity of these compounds was tested against Escherichia coli K12, Bacillus cereus, Enterobacter aerogenes, Streptococcus aureus, and Enterobacter cloacae. The antimicrobial activity was also tested against modifications of the Saccharomyces cerevisiae: the MutL Homolog 1 (MLH1), Slow Growth Suppressor (SGS1), O-6-MethylGuanine-DNA methyltransferase (MGT1), and RADiation sensitive (RAD14), carrying mutations related to different cancer types. In addition, the results were compared with the effect of ampicillin and kanamycin. The SCB extracts showed up to 90% growth inhibition against B. cereus at 200–800 μg/mL and 50% growth inhibition against S. aureus at 800 μg/mL. The inhibitory effect against modified yeast SGS1, RAD14, and MLH1 was 50–80% at 800 μg/mL. The percentage of inhibition and the phenolic compound contents differed depending on the origin of the SCB sample. These findings are promising for using this industrial byproduct to obtain compounds for nutraceutical, food additive, or medical uses.

Exploration of microwaves for biorefining of phenolic antioxidants from Citrus reticulata peels: Spectrophotometric and spectroscopic analyses

Citrus industries discard an enormous waste as a by-product during juice processing, which is attracting researchers due to its functional/nutraceutical properties. To utilize the functional potential of kinnow peels, bioactives have been extracted using several green extraction techniques. In the present research, the microwave-assisted technique has been used to extract bioactive phytochemicals (phenolic and total antioxidants) from kinnow peels. Process variables, such as microwave power, solvent concentration, liquid to solid ratio (LSR), and time, were studied to maximize the extract yield of phenolic and antioxidant compounds from kinnow peels. Maximum phenolic content (2.48 mg GAE/g peels) with antioxidant activity of 63.20% and 6.38 mmol Fe2+/100 g peels for DPPH and FRAP assays, respectively, was observed at 300 W, 80% ethanol, and LSR of 50 ml/g after 6 min extraction time. The presence of phenolic and antioxidant compounds was confirmed by FT-IR and GC-EI MS techniques. Novelty impact statement Microwave-assisted extraction has emerged as an efficient non-contact heating extraction technique. But there is inadequate data on the valorization of kinnow processing by-products using microwave-assisted extraction. The present research has been conducted to investigate the effect of process parameters of microwave-assisted technique on the extraction of phenolic and antioxidant compounds from kinnow peels. This study could encourage the scale-up process for the value addition of agro-industrial waste by efficient extraction of bioactive compounds from citrus processing by-products.

Enhancing aromatic yield from catalytic pyrolysis of Ca2+-loaded lignin coupled with metal-modified HZSM-5

Catalytic fast pyrolysis of lignin is easy to cause agglomeration and coking, resulting in low-yield aromatic hydrocarbons. Catalytic pyrolysis of modified lignin combined with metal-modified HZSM-5 was proposed to enhance the aromatic yield. The experiment results showed that chemical modification with Ca(OH)2 not only inhibited the agglomeration behavior of lignin but also increased the yield of light phenolic compounds. Moreover, Ca2+-loaded lignin combined with metal-modified HZSM-5 was conducive to the formation of aromatics. The total yield of aromatics from the catalytic fast pyrolysis of Ca2+-loaded lignin over Zn/HZSM-5 was improved from 31.1 to 46.1 mg/g. The mechanism insight showed that Ca2+ modification realized the chemical combination between Ca2+ and the functional groups which are responsible for the agglomeration of lignin, and then the introduction of the Zn species suppressed the hydrogen transfer reaction and enhanced the dehydrogenation pathway, resulting in the increase of aromatic yield.

Optimization of Microwave-Assisted Extraction of Polyphenols from Lemon Myrtle: Comparison of Modern and Conventional Extraction Techniques Based on Bioactivity and Total Polyphenols in Dry Extracts

The aromatic herb lemon myrtle is a good source of polyphenols, with high antioxidant and antimicrobial capacity. In this study, the green extraction technique microwave-assisted extraction (MAE) was applied and the extraction parameters were optimized using response surface methodology (RSM) to maximize the extraction yield of phenolic compound and antioxidant properties. Then, it was compared with other popular novel and conventional extraction techniques including ultrasound-assisted extraction (UAE) and shaking water bath (SWB) to identify the most effective technique for extraction of phenolic compounds from lemon myrtle. The results showed that the MAE parameters including radiation time, power, and sample to solvent ratio had a significant influence on the extraction yield of phenolic compounds and antioxidant capacity. The optimal MAE conditions were radiation time of 6 min, microwave power of 630 W, and sample to solvent ratio of 6 g/100 mL. Under optimal conditions, MAE dry extract had similar levels of total phenolic compounds (406.67 ± 8.57 mg GAE/g DW), flavonoids (384.57 ± 2.74 mg CE/g DW), proanthocyanidins (336.54 ± 7.09 mg CE/g DW), antioxidant properties, and antibacterial properties against (Staphylococcus lugdunensis and Bacillus cereus) with the other two methods. However, MAE is eight-times quicker and requires six-times less solvent volume as compared to UAE and SWB. Therefore, MAE is recommended for the extraction of polyphenols from lemon myrtle leaf.