Maximizing polyphenol yield: ultrasound-assisted extraction and antimicrobial potential of mango peel.

This study investigated the ultrasound-assisted extraction (UAE) techniques used to enhance the polyphenols and antioxidants of mango peel extract (MPE). Additionally, it explored the bacteriostatic activity of MPE against various microorganisms. The UAE method was optimized using response surface methodology (RSM) at different times, temperatures, and ratios, with optimal conditions found to be 35 minutes, 45 °C, and a 1:35 ratio. The optimized yield results for total polyphenol content (TPC) were 17.33 ± 1.57 mg GAE/g, total flavonoid content (TFC) was 12.14 ± 0.29 mg QE/g, and radical scavenging activity (RSA) was 72.11 ± 2.19%. These response models were extremely significant with p-values less than 0.05. MPE showed selective effectiveness against Bacillus cereus, Geobacillus stearothermophilus, and Escherichia coli (E. coli). The results highlight the potential of mango peel as a sustainable source of bioactive compounds, contributing to waste reduction in the food industry and the development of natural antimicrobial agents. This study contributes to further research on the application of MPE in processed foods.

Modified zero-valent iron nanoparticles enhanced remediation of PCBs-contaminated soil.

The high toxicity and persistence of polychlorinated biphenyls (PCBs) in the environment require effective remediation of PCBs-contaminated soil. This study used polylactic acid (PLA) and polyethylene glycol 4000 (PEG-4000) to modify zero-valent iron nanoparticles (nZVI) and conducted characterization analysis. It was found that when the addition amount of PLA was 2 %, the dispersion of modified nZVI was better. The initial pH and water to soil ratio were subjected to single factor experiments and fitted using RSM response surface methodology. The optimal reaction conditions were obtained as follows: the addition amount was 84 g·kg-1, the initial pH was 5.41, and the optimal removal rate was 74 % when the ratio of water to soil was 1.8:1. PLA and PEG-4000 were biodegradable substances that played crucial roles in enhancing the effectiveness of nZVI for PCBs-contaminated soil. By encapsulating nZVI with PLA, we significantly reduced its oxidation when exposed to air. Additionally, the inclusion of PEG-4000 helped prevent the particles from clumping together. The synergistic effect of them increased the effective reaction of nZVI and PCBs and ultimately leading to more efficient remediation. This study offered a new pathway for the efficient green remediation of PCBs-contaminated soil.

Scenedesmus rubescens Heterotrophic Production Strategies for Added Value Biomass.

Microalgae attract interest worldwide due to their potential for several applications. Scenedesmus is one of the first in vitro cultured algae due to their rapid growth and handling easiness. Within this genus, cells exhibit a highly resistant wall and propagate both auto- and heterotrophically. The main goal of the present work is to find scalable ways to produce a highly concentrated biomass of Scenedesmus rubescens in heterotrophic conditions. Scenedesmus rubescens growth was improved at the lab-scale by 3.2-fold (from 4.1 to 13 g/L of dry weight) through medium optimization by response surface methodology. Afterwards, scale-up was evaluated in 7 L stirred-tank reactor under fed-batch operation. Then, the optimized medium resulted in an overall productivity of 8.63 g/L/day and a maximum biomass concentration of 69.5 g/L. S. rubescens protein content achieved approximately 31% of dry weight, similar to the protein content of Chlorella vulgaris in heterotrophy.

Optimization of anaerobic digestion parameters for biogas production from pineapple wastes co-digested with livestock wastes.

The demand for energy has been growing over the years to match development and population growth. The current sustainable development model advocates for the use of renewable (green) energy sources with an aim of lowering carbon emissions thereby mitigating the effects of climate change. A circular economy aspires to keep materials in use for as long as possible thus the reuse of agricultural waste especially in energy generation is a step in this direction. This study reports on the optimization of anaerobic digestion parameters for biogas production when wastes from pineapple are co-digested with those from livestock. The volume of biogas yield was optimized with regards to temperature, pH value, and mixing ratio of the substrates using Box Behnken Design (BBD), a class of Response Surface Methodology (RSM). This was achieved through a software package, Design Expert 13.The experiments were performed using Rehau home gas systems of 6 m3 in Jomo Kenyatta University of Agriculture and Technology. Pineapple wastes were co-digested with livestock waste in the ratio of 1:1, 1:2 and 1:3. The numerical optimization results revealed that the maximum biogas yield was 1.98 m3 when the pH was set at 6.0, temperature at 30 °C and pineapple mixing ratio at 62.5%. The results from this study can form a basis for policy makers in formulating strategies to guide adoption of biogas generated from agricultural waste as a key green energy for the economy.

Avaliação do impacto da temperatura e da concentração de IPTG na expressão da proteína Rzv-TSP2 derivada de Schistosoma mansoni

Schistosomiasis is endemic in tropical countries and affects 240 million people around the world, with the poorest countries and regions being the most affected because they have poor or no sanitation conditions. In Brazil, the parasite Schistosoma mansoni is the cause of the disease, whose records point 423,117 cases in the country between the years 2009 and 2019. A vaccine would be the best way to reduce the occurrence of schistosomiasis, however, due to its chronic nature of infections, it has not yet been possible to create a vaccine that produces consistent immunogenicity. Therefore, the aim of this work is to optimize the production of the vaccine candidate SmTSP-2 (protein located in the tegument of the parasite) fused to rizavidin, aiming its use in the construction of a Multiple Antigen Presenting System (MAPS). For this, two independent variables involved in the expression process were evaluated: temperature and concentration of the expression inducer IPTG. Using the Response Surface Methodology (RSM) and analyzing the results in Western Blot, it was possible to observe that temperature has a more significant role in protein expression compared to IPTG concentration: at 22oC the expression of Rzv-TSP2 occurred in soluble and insoluble fractions, in both IPTG concentrations tested (0.1 mM and 1 mM). At 37°C, the protein was only expressed in the insoluble fraction at 1 mM IPTG concentration.

A esquistossomose é endêmica em países tropicais e afeta 240 milhões de pessoas ao redor do mundo, sendo os países e regiões mais pobres os mais afetados por possuírem condições de saneamento precárias ou inexistentes. No Brasil, o parasito Schistosoma mansoni é o causador da doença, cujo os registros apontam 423.117 casos no país entre os anos de 2009 e 2019. Uma vacina seria a melhor maneira de reduzir a ocorrência da esquistossomose, entretanto, devido ao seu caráter crônico de infecções, ainda não foi possível criar uma vacina que produzisse uma imunogenicida de consistente. Dado a isso, o objetivo deste trabalho é otimizar a produção do candidato vacinal SmTSP-2 (proteína localizada no tegumento do parasito) fusionada a rizavidina, visando sua utilização na construção de um sistema de apresentação de múltiplos antígenos (MAPS). Para isso, foram avaliadas duas variáveis independentes envolvidas no processo de expressão: temperatura e concentração do indutor de expressão IPTG. Utilizando a metodologia RSM (Response Surface Methodology) e analisando os resultados por Western Blot, foi possível observar que a temperatura possui um papel mais significativo na expressão da proteína em comparação a concentração de IPTG. Enquanto a 22oC a expressão de Rzv-TSP2 se deu nas frações solúvel e insolúvel, em ambas as concentrações de IPTG testadas (0,1 mM e 1 mM), na temperatura de 37oC as proteínas só foram expressas na fração insolúvel, sob a concentração de 1 mM de IPTG.

Application of response surface methodology (RSM) for optimization of the supercritical CO2 extract of oil from Zanthoxylum bungeanum pericarp: Yield, composition and gastric protective effect.

Supercritical carbon-dioxide (SC-CO2) is a promising two-phase technology for flavor components (volatile oil and alkylamides) extract from Zanthoxylum bungeanum pericarp. However, the gastric protective effect of SC-CO2 extract from Z. bungeanum (SZB) have not been systematically investigated. In this study, response surface methodology (RSM) was employed to optimize the yield of SZB, and the average yield of 11.07 % were obtained under optimal parameters (30 MPa, 43 °C and time 75 min). Here, limonene, linalool and hydroxy-α-sanshool were identified as the main compounds of SZB by GC-MS and UPLC-Q-Extractive Orbitrap/MS analysis. When the gastric protective effect of SZB (5, 10 and 20 mg/kg, p.o.) were evaluated, significant increase in body weight and organ indexes of rat, and decreased gastric lesion were observed. Furthermore, nineteen serum metabolites were regarded as the potential biomarkers for the gastric protective effect of SZB. Collectively, this study provides a comprehensive perspective into the chemical composition analysis and gastric protective effect of Z. bungeanum SC-CO2 extract.

PERISCOPE-Opt: Machine learning-based prediction of optimal fermentation conditions and yields of recombinant periplasmic protein expressed in Escherichia coli.

Optimization of the fermentation process for recombinant protein production (RPP) is often resource-intensive. Machine learning (ML) approaches are helpful in minimizing the experimentations and find vast applications in RPP. However, these ML-based tools primarily focus on features with respect to amino-acid-sequence, ruling out the influence of fermentation process conditions. The present study combines the features derived from fermentation process conditions with that from amino acid-sequence to construct an ML-based model that predicts the maximal protein yields and the corresponding fermentation conditions for the expression of target recombinant protein in the Escherichia coli periplasm. Two sets of XGBoost classifiers were employed in the first stage to classify the expression levels of the target protein as high (>50 mg/L), medium (between 0.5 and 50 mg/L), or low (<0.5 mg/L). The second-stage framework consisted of three regression models involving support vector machines and random forest to predict the expression yields corresponding to each expression-level-class. Independent tests showed that the predictor achieved an overall average accuracy of 75% and a Pearson coefficient correlation of 0.91 for the correctly classified instances. Therefore, our model offers a reliable substitution of numerous trial-and-error experiments to identify the optimal fermentation conditions and yield for RPP. It is also implemented as an open-access webserver, PERISCOPE-Opt (http://periscope-opt.erc.monash.edu).

"Q-markers targeted screening" strategy for comprehensive qualitative and quantitative analysis in fingerprints of Angelica dahurica with chemometric methods.

Angelica dahurica is a famous functional food and herb. To guarantee quality of A. dahurica, a strategy "Q-markers targeted screening" was successfully developed by sufficient extraction of compounds and the targeted screening of qualitative and quantitative markers calculated through chemometric methods based fingerprints. Accelerated solvent extraction was selected due to its prominent advantages exhibiting the maximum extraction yields and varieties of compounds and especially excellent reproducibility (RSD < 1). After extraction, the fingerprints of A. dahuricae samples were established. For the preliminary herb authenticity, the targeted screening of 23 quantitative markers were performed by similarity analysis and hierarchical cluster analysis based on the fingerprints, which were identified by liquid chromatography tandem mass spectrometry (LC-MS). Subsequently, for further quality control, the targeted screening of nine quantitative markers were done by similarity analysis & linear discriminant analysis, which were determined by LC. Lastly, the strategy was successfully applied to quality assessment of A. dahurica samples.

Pomegranate peels waste hydrolyzate optimization by Response Surface Methodology for Bioethanol production.

Unwanted agricultural waste is largely comprised of lignocellulosic substrate which could be transformed into sugars. The production of bioethanol from garbage manifested an agreeable proposal towards waste management as well as energy causation. The goal of this work is to optimize parameters for generation of bioethanol through fermentation by different yeast strains while Saccharomyces cerevisiae used as standard strain. The low cost fermentable sugars from pomegranate peels waste (PPW) were obtained by hydrolysis with HNO3 (1 to 5%). The optimum levels of hydrolysis time and temperature were elucidated via RSM (CCD) ranging from 30 to 60 min and 50 to 100 °C respectively. The result shows that optimum values (g/L) for reducing sugars was 61.45 ± 0.01 while for total carbohydrates was 236 ± 0.01. These values were found when PPW was hydrolyzed with 3% HNO3, at 75 °C for one hour. The hydrolyzates obtained from the dilute HNO3 pretreated PPW yielded a maximum of 0.43 ± 0.04, 0.41 ± 0.03 g ethanol per g of reducing sugars by both Metchnikowia sp. Y31 and M. cibodasensis Y34 at day 7 of ethanologenic experiment. The current study exhibited that by fermentation of dilute HNO3 hydrolyzates of PPW could develop copious amount of ethanol by optimized conditions.

Punica granatum waste to ethanol valorisation employing optimized levels of saccharification and fermentation.

Pomegranate peels (PPW) as municipal waste is inexpensive biomass that could be a renewable source of sugars particularly rich in hemicellulosic contents. The subsequent conversion of available sugars in PPW can provide prospective strategy for cost-effective bioenergy production. In this study, an experimental setup based on CCD was implemented with the aim of bioconversion of biomass into bioethanol. The factors considered were Hydrochloric acid concentration (X1), the hydrolysis temperature (X2) and time (X3) for optimization with dilute Hydrochloric acid (HCl) saccharification. The present study investigates the optimised level of bioethanol synthesis from acid pre-treated PPW explained by RSM. Subsequently, three yeasts viz. Saccharomyces cerevisiae K7, Metschnikowia sp. Y31 and M. cibodasensis Y34 were utilized for fermentation of acid hydrolysed and detoxified feed stocks. Optimum values of reducing sugars 48.02 ± 0.02 (gL-1) and total carbohydrates 205.88 ± 0.13 (gL-1) were found when PPW was hydrolyzed with 1% HCl concentration at 100˚C of temperature for 30 min. Later on, fermentation of PPWH after detoxification with 2.5% activated charcoal. The significant ethanol (g ethanol/g of reducing sugars) yields after fermentation with Metschnikowia sp. Y31 and M. cibodasensis Y34 found to be 0.40 ± 0.03 on day 5 and 0.41 ± 0.02 on last day of experiment correspondingly. Saccharomyces cerevisiae K7 also produce maximum ethanol 0.40 ± 0.00 on last day of incubation utilizing the PPWH. The bioconversion of commonly available PPW into bioethanol as emphasize in this study could be a hopeful expectation and also cost-effective to meet today energy crisis.

Optimization of growing conditions for pigments production from microalga Navicula incerta using response surface methodology and its antioxidant capacity.

Navicula incerta is a marine microalga distributed in Baja California, México, commonly used in aquaculture nutrition, and has been extended to human food, biomedical, and pharmaceutical industries due to its high biological activity. Therefore, the study aimed to optimize culture conditions to produce antioxidant pigments. A central composite experimental design and response surface methodology (RSM) was employed to analyze the best culture conditions. The medium (nitrogen-deficient concentrations), salinity (PSU = Practical Salinity Unity [g/kg]), age of culture (days), and solvent extraction (ethanol, methanol, and acetone) were the factors used for the experiment. Chlorophyll a (Chl a) and total carotenoids (T-Car), determined spectroscopically, were used as the response variables. The antioxidant capacity was evaluated by DPPH• and ABTS•+ radical inhibition, FRAP, and anti-hemolytic activity. According to the overlay plots, the optimum growth conditions for Chl a and T-Car production were the following conditions: medium = 0.44 mol·L-1 of NaNO3, salinity = 40 PSU, age of culture: 3.5 days, and solvent = methanol. The pigment extracts obtained in these optimized conditions had high antioxidant activity in ABTS•+ (86.2-92.1% of inhibition) and anti-hemolytic activity (81.8-96.7% of hemolysis inhibition). Low inhibition (33-35%) was observed in DPPH•. The highest value of FRAP (766.03 ± 16.62 µmol TE/g) was observed in the acetonic extract. The results demonstrated that RSM could obtain an extract with high antioxidant capacity with potential applications in the biomedical and pharmaceutical industry, which encourages the use of natural resources for chemoprevention of chronic-degenerative pathologies.

Statistically Designed Extraction of Herbs Using Ultrasound Waves: A Review.

BACKGROUND: Extraction is the foremost step to isolate the natural constituents from a medicinal plant and leads the process of development of herbal formulation from bench to bed. INTRODUCTION: In the field of extraction, the optimization approach helps in achieving better yield and quality where a response of concern is determined or influenced by various variables. This review aimed at congregating the application of different statistical designs (CCD/BBD) to optimize the Ultrasound assisted extraction (UAE) parameters for the recovery of various plant actives belonging to different categories. METHODOLOGY: The literature published during the last decade in the various reputed databases (Web of Science, Pubmed, Scopus) was reviewed and compiled to reveal the role of response surface methodology in optimizing the influential parameters involved in the ultrasound assisted extraction of herbs. CONCLUSION: From the present investigations, it can be concluded that the different variables, such as sonication power, temperature, time, solute to solvent ratio are generally optimized in UAE of herbs. Moreover, it has also been evidenced from the review of published data that the flavonoids/phenolic acids (>50%) leads the race for the extraction of plants using sound waves. It can be said that the statistically designed UAE has a vast prospective in bringing about a green mutiny in the herbal drug industry and the modeling of various parameters shall be able to absolutely build up a complete drug innovation course (bench to bed).

Advanced process integration for supercritical production of biodiesel: Residual waste heat recovery via organic Rankine cycle (ORC).

Biodiesel production using supercritical methanolysis has received immense interest over the last few years. It has the ability to convert high acid value feedstock into biodiesel using a single-pot reaction. However, the energy intensive process is the main disadvantage of supercritical biodiesel process. Herein, a conceptual design for the integration of supercritical biodiesel process with organic Rankine cycle (ORC) is presented to recover residual hot streams and to generate electric power. This article provides energy and techno-economic comparative study for three developed scenarios as follows: original process with no energy integration (Scenario 1), energy integrated process (Scenario 2) and advanced energy integrated process with ORC (Scenario 3). The developed integrated biodiesel process with ORC resulted in electric power generation that has not only satisfied the process electric requirement but also provided excess power of 257 kW for 8,000 tonnes/annum biodiesel plant. The techno-economic comparative analysis resulted in favouring the third scenario with 36% increase in the process profitability than the second scenario. Sensitivity analysis has shown that biodiesel price variation has significant effect on the process profitability. In summary, integrating supercritical biodiesel production process with ORC appears to be a promising approach for enhancing the process techno-economic profitability and viability.

Design and characterization of Squalene-Gusperimus nanoparticles for modulation of innate immunity.

Immunosuppressive drugs are widely used for the treatment of autoimmune diseases and to prevent rejection in organ transplantation. Gusperimus is a relatively safe immunosuppressive drug with low cytotoxicity and reversible side effects. It is highly hydrophilic and unstable. Therefore, it requires administration in high doses which increases its side effects. To overcome this, here we encapsulated gusperimus as squalene-gusperimus nanoparticles (Sq-GusNPs). These nanoparticles (NPs) were obtained from nanoassembly of the squalene gusperimus (Sq-Gus) bioconjugate in water, which was synthesized starting from squalene. The size, charge, and dispersity of the Sq-GusNPs were optimized using the response surface methodology (RSM). The colloidal stability of the Sq-GusNPs was tested using an experimental block design at different storage temperatures after preparing them at different pH conditions. Sq-GusNPs showed to be colloidally stable, non-cytotoxic, readily taken up by cells, and with an anti-inflammatory effect sustained over time. We demonstrate that gusperimus was stabilized through its conjugation with squalene and subsequent formation of NPs allowing its controlled release. Overall, the Sq-GusNPs have the potential to be used as an alternative in approaches for the treatment of different pathologies where a controlled release of gusperimus could be required.

Kerf Taper Defect Minimization Based on Abrasive Waterjet Machining of Low Thickness Thermoplastic Carbon Fiber Composites C/TPU.

Carbon fiber-reinforced thermoplastics (CFRTPs) are materials of great interest in industry. Like thermosets composite materials, they have an excellent weight/mechanical properties ratio and a high degree of automation in their manufacture and recyclability. However, these materials present difficulties in their machining due to their nature. Their anisotropy, together with their low glass transition temperature, can produce important defects in their machining. A process able to machine these materials correctly by producing very small thermal defects is abrasive waterjet machining. However, the dispersion of the waterjet produces a reduction in kinetic energy, which decreases its cutting capacity. This results in an inherent defect called a kerf taper. Also, machining these materials with reduced thicknesses can increase this defect due to the formation of a damage zone at the beginning of cut due to the abrasive particles. This paper studies the influence of cutting parameters on the kerf taper generated during waterjet machining of a thin-walled thermoplastic composite material (carbon/polyurethane, C/TPU). This influence was studied by means of an ANOVA statistical analysis, and a mathematical model was obtained by means of a response surface methodology (RSM). Kerf taper defect was evaluated using a new image processing methodology, where the initial and final damage zone was separated from the kerf taper defect. Finally, a combination of a hydraulic pressure of 3400 bar with a feed rate of 100 mm/min and an abrasive mass flow of 170 g/min produces the minimum kerf taper angle.

Optimization of enzymatic hydrolysis of cellulosic fraction obtained from stranded driftwood feedstocks for lipid production by Solicoccozyma terricola.

Stranded driftwood feedstocks may represent, after pretreatment with steam explosion and enzymatic hydrolysis, a cheap C-source for producing biochemicals and biofuels using oleaginous yeasts. The hydrolysis was optimized using a response surface methodology (RSM). The solid loading (SL) and the dosage of enzyme cocktail (ED) were variated following a central composite design (CCD) aimed at optimizing the conversion of carbohydrates into lipids (YL) by the yeast Solicoccozyma terricola DBVPG 5870. A second-order polynomial equation was computed for describing the effect of ED and SL on YL. The best combination (ED = 3.10%; SL = 22.07%) for releasing the optimal concentration of carbohydrates which gave the highest predicted YL (27.32%) was then validated by a new hydrolysis. The resulting value of YL (25.26%) was close to the theoretical maximum value. Interestingly, fatty acid profile achieved under the optimized conditions was similar to that reported for palm oil.

Response surface based optimization of laccase production from Bacillus sp. MSK-01 using fruit juice waste as an effective substrate.

Laccases are multicopper oxidases containing four copper atoms per monomer distributed in three redox sites. Because of its tremendous applications in different areas, isolation of new laccases with wide range of industrial implementation. The present study focuses on the optimization of laccase production from Bacillus sp. MSK-01 under solid state fermentation conditions using fruit juice waste as the substrate. MSKLAC was produced extracellularly by the bacteria. This laccase was able to oxidize ABTS and syringaldazine. Various nutritional and environmental factors were utilized for increasing the enzyme yield. Plackett Burman was used to study the influence of input parameters on laccase yield. Tween-80, initial moisture ratio and magnesium sulphate were the major influencing factor affecting laccase yield. Central composite design of RSM was used for the modelling of experiment. Desirability approach was used to optimize laccase yield. Maximum laccase yield of 1645 IUg-1 was obtained when 0.55% of tween -80, 1:2.34 initial moisture ratio and 300µM magnesium sulphate was used. A 470 fold increase in the yield of laccase from unoptimized condition was obtained.

Increasing Yield and Antioxidative Performance of Litchi Pericarp Procyanidins in Baked Food by Ultrasound-Assisted Extraction Coupled with Enzymatic Treatment.

Extraction with organic solvents is a traditional method to isolate bioactive compounds, which is energy-wasting and time-consuming. Therefore, enzyme and ultrasound treatments were combined to assist the extraction of oligomeric procyanidins from litchi pericarp (LPOPC), as an innovative approach to replace conventional extraction methods. Under optimum conditions (enzyme concentration 0.12 mg/mL, ultrasonic power 300 W, ultrasonic time 80 min, and liquid/solid ratio 10 mL/g), the yield of LPOPC could be improved up to 13.5%. HPLC analysis indicated that the oligomeric procyanidins (OPC) content of LPOPC from proposed extraction was up to 89.6%, mainly including (-)-epicatechin, procyanidin A1, A2, and A-type procyanidin trimer. Moreover, LPOPC powder was added in baked food to inhibit the lipid peroxidation. It was found that 0.2% (w/w) of LPOPC could maintain the quality of cookies in the first 7 days, by decreasing the peroxide values. The procyanidin dimers and trimers in LPOPC played more important roles as antioxidants compared to monomers during storage. The results also showed that the combined extraction process can be considered as a useful and efficient method for the extraction of functional components from other plant sources.

Enhanced production of total flavones from Inonotus baumii by multiple strategies.

As one kind of important secondary metabolites produced by Inonotus baumii, flavones can be applied in food, medicine, and other industries due to their biological activities such as antioxidant, anticancer, and antibacterial activity. To enhance total flavone production in submerged fermentation of I. baumii, three different strategies, optimization of fermentation parameters by statistical designs including Plackett-Burman design and response surface methodology, addition of precursors and elicitors, and two-phase culture, were used. The production of total flavones (PTF) reached 1532.83 mg/L when the optimized medium was used. All precursors and elicitors can increase the PTF. The maximum PTF (2184.06 mg/L, up to 1.57-fold) was obtained with the addition of both AgNO3 and glutathione in fermentation media. Interestingly, when 0.5% (w/v) DM130 macroporous resin as adsorbent was added to fermentation broth on day 4 of culture, the highest production reached 2407.79 mg/L with this two-phase culture strategy. These methods can be further applied to large-scale industrial production and broaden the application of flavones.

Ultrasound-assisted extraction process of phenolic antioxidants from Olive leaves: a nutraceutical study using RSM and LC-ESI-DAD-MS.

In recent years, there has been an ever growing interest in finding new natural sources of food antioxidants. As a main fruit crop, olive is also valued due to its phenolic-containing leaves. Mathematically based optimization methods are used as powerful tools to extract different antioxidant compounds. The present study is aimed to provide an efficient extraction method for total phenol content (TPC), total flavonoid content (TFC) and antioxidant ability (DPPH scavenging assay and FRAP). The effects of ultrasonic temperature (35-65 °C), ultrasonic time (5-15 min), and ethanol to water ratio (Et: W) (25-75%) were evaluated. Second-order polynomial models were used through a rotatable Box-Behnken design (BBD) consisting of 15 experimental runs with three replicates at the center point. Interactional effects of the studied factors were significant in most cases for all responses. The highest extraction efficiency was found to be fifty-one percent of ethanol (65 °C, 15 min) to water ratio. Under optimal conditions, values for TPC, TFC, DPPHsc and FRAP assay were 183.4 (mg GAE. g-1 DW), 696.77 (mg Quercetin. g-1 DW), 78.98 (DPPHsc %) and 1942 µmol Fe+2/g DW, respectively. R2 values (R2 > 0.92) showed that RSM models could efficiently predict the yield of all responses. In the LC-ESI-MS-DAD profiling of the optimized extract, 27 compounds were identified with oleuropein as the main compound. In the present study, olive leaf is introduced as a promising source of natural antioxidant and can be used in food industries following further studies.