Extraction process optimization for maximizing total polyphenol content in cashew nut testa (Anacardium occidentale L.) extract

Optimization of ultrasound-assisted extraction of phenolic content & antioxidant activity of hog plum (Spondias pinnata L. f. kurz) pulp by response surface methodology

The present study aims to optimize the natural deep eutectic solvent (NADES) as a green solvent-based microwave-assisted extraction (MAE) of total polyphenols content (TPC) from Mitragyna speciosa Korth Havil leaves using response surface methodology (RSM). Preparation of natural deep eutectic solvent (NADES) as a green solvent was performed by melting the two-component of malic acid and glucose using a magnetic stirrer. The leaves sample was extracted using the NADES-MAE method with various extraction conditions with four factors and three levels (Box Behnken Design) and optimized using RSM with licensed software of Design Expert V12. TPC was determined using a Folin-Ciocalteau reagent and absorbance was measured on a UV-VIS spectrophotometer at 770 nm and gallic acid as a standard. This study was obtained the optimum extraction conditions include: NADES ratio (malic acid: glucose) of 1:2 g/g, 50% microwave power, a solvent-sampel ratio of 12:1 mL/g, and extraction time for 7 minutes. The optimum conditions were obtained according to the equation formula: TPC = 165.17 – 33.97X1 + 38.36X2 – 6.08X3 + 16.12X4 – 62.77X1X2 + 79.61X12X2, where a R2 value = 0.7102 with a TPC prediction of 402.087±43.81 mg GAE/g sample. These conditions can be used to extract TPC from this plant efficiently, quickly, easily, and environmentally friendly.

Recently, the interest towards phenol compounds has progressed. In this study, a response surface methodology (RSM) was applied to predict the optimum conditions for extraction of phenolic from red rice bran. Firstly, the effects of ethanol concentration (20–80%), added acetic acid concentration (0–20%), extraction time (0–6.5 hours), temperature (25–100oC), number of extraction cycles (1–4) and solid–solvent ratio (1/4–1/10 w/v) on total polyphenolic content (TPC) of red rice bran were found. After that, three parameters such as solvent concentration (48–68%), added acetic acid concentration (10–15%) and extraction time (120–240 min) were able to be optimized using the Box Behnken design (BBD) with a quadratic regression model built by using RSM. The experiment was designed according to 30 runs with 2 blocks; each block consists of 3 central points and 1 replicate. This design was set up for 3 factors to optimise the response in term of TPC extraction. The extracts were analyzed the TPC spectrophotometrically according to the Folin-Ciocalteu colorimetric assay. The optimal extraction conditions were determined as follows: ethanol concentration of 54.5%, added acetic acid concentration of 13.1%, extraction time of 210 min, temperature of 40oC, 3 cycles of extraction and solid–solvent ratio 1/6 w/v. Using these extraction conditions, the experimental yield of TPC was 2391.1±5.9 mg GAE/100 g dry weight (dw) that was in close significant agreement with predicted value (p < 0.05). The experimental results were fitted to a second order quadratic polynomial model, and they have shown a good fit to the proposed model (R2 = 0.99). With these conditions, the antioxidant capacity assayed by 1,1–diphenyl–2–picrylhydrazyl (DPPH) radical–scavenging activity in term of IC50 value of extract was 108.1±2.9 μg dw/mL. The study result indicates the suitability of the developed model and the success of RSM in optimizing the extraction conditions.

The Moroccan picholine tree’s leaves contain phenolic compounds that benefit human health. However, the amount and type of these compounds can vary based on factors such as the extraction method and conditions. This study aimed to improve phenolic compounds’ extraction while minimising harmful chemicals’ use. It has been found that using ethanol as a solvent with ultrasonic extraction is the most effective and environmentally friendly technique. Several parameters, such as the extraction time, solid/solvent ratio, and ethanol concentration as independent variables, were evaluated using a surface response method (RSM) based on the Box–Behnken design (BBD) to optimize the extraction conditions. The experimental data were fitted to a second-order polynomial equation using multiple regression analysis and also examined using the appropriate statistical methods. In optimal conditions, the ultrasonic time, the ratio (solvent/solid) and the concentration (ethanol/water), the content of total polyphenols (TPC), total flavonoids (TFC), and antioxidant activity (by DPPH, ABTS, FRAP) were, respectively, 74.45 ± 1.22 mg EAG/g DM, 17.08 ± 1.85 mg EC/g DM, 83.45 ± 0.89% 82.85 ± 1.52%, and 85.01 ± 2.35%. The identification of phenolic compounds by chromatography coupled with mass spectrum (HPLC-MS) under optimal conditions with two successive extractions showed the presence of hydroxytyrosol, catechin, caffeic acid, vanillin, naringin, oleuropein, quercetin, and kaempferol at high concentrations.

Background: In this study, microwave extraction was used, which is an effective method to extract useful bioactive substances as it requires low quantities of solvent and short time periods. The aim of this study was to determine the optimal extraction conditions for Agrimonia pilosa Ledeb. Methods and Results: The independent variables were ethanol concentration, microwave power, and extraction time, each of which had five levels. The dependent variables were total polyphenol and total flavonoid content, and DPPH radical scavenging activity. To determine the optimal extraction conditions for bioactive compounds, a response surface methodology was employed. Contour maps were generated from polynomial equations. The optimal conditions were then assumed by superimposing these contour maps. Based on the resulting graph, the optimal microwave extraction conditions for Agrimonia pilosa Ledeb were determined as 42 - 48% ethanol concentration, 240 - 280W microwave power, and 13 - 20 min of extraction time. Conclusions: Ethanol concentration had a significant effect on microwave extraction, in terms of total polyphenol and total flavonoid content, as well as DPPH radical scavenging activity. Microwave power and extraction time influenced the total polyphenol content, but not the total flavonoid content or the DPPH radical scavenging activity.

In this study, the extraction of phenolic compounds from Pouzolzia Zeylanica L. Benn was conducted by using pure water as a solvent. The optimal conditions for the extraction of three phenolic compounds such as polyphenols, flavonoids and tannins were determined by using response surface methodology (RSM). A central composite design (CCD) was applied to investigate the effects of three independent variables, namely the ratio of water-to-dried material (20:1 to 30:1, v/w), temperature (70 to 90oC ) and time extraction (20 to 40 minutes). The dependent variables were total polyphenol content (TPC), total flavonoid content (TFC) and tannin content (TC). A second-order polynomial model was used for predicting the response. Optimized conditions for bioactive compounds extraction, water-to-dried material ratio, time and temperature extraction were 27 (v/w), 30 minutes and 81oC, respectively. The experimental values agreed with predicted values within a 95% confidence interval. Total polyphenol, flavonoid and tannin content extracted by these optimized conditions were achieved (521 mgGAE/100g dried material (DM), 363 mgQE/100g DM and 643 mgTAE/100g DM, respectively).

본 연구에서는 치아씨의 항산화 활성을 증가시키기 위하여 추출용매 종류와 용매농도, 추출시간과 추출온도를 달리하여 총 폴리페놀 함량과 DPPH 라디칼 소거능을 측정한 후 반응표면분석을 이용하여 최적조건을 수립하였다. 치아씨 추출조건은 에탄올과 메탄올용매 모두에서 추출용매 60%, 추출시간 130분과 추출온도 <TEX>$20^{\circ}C$</TEX>에서 총 폴리페놀 871.00mg%(<TEX>$R^2=0.9507$</TEX>), 557.70mg%(<TEX>$R^2=0.9784$</TEX>)로 가장 함량이 많았고, DPPH 라디칼 소거능은 72.14%(<TEX>$R^2=0.9675$</TEX>), 52.79%(<TEX>$R^2=0.9524$</TEX>)의 항산화력을 보였다. 용매종류에서는 에탄올 추출용매가 메탄올 추출용매보다 같은 조건에서는 월등히 높은 항산화력을 보여 에탄올이 치아씨 추출용매로 더 우수한 용매로 선정되었다. 또한 반응표면분석 결과, 용매추출 조건에서는 에탄올 용매에서는 용매추출 시간이나 온도보다는 용매농도에 가장 큰 영향을 받았고, 메탄올 추출조건에서는 용매추출 시간에서 가장 큰 영향력을 주었다. 반응표면분석 후 용매 농도, 시간과 온도의 최적 추출조건의 범위는 에탄올 추출조건은 에탄올농도 63%, 추출시간 100분과 추출온도 <TEX>$18^{\circ}C$</TEX>가 최적조건이고, 메탄올 추출조건에서는 추출농도 65%, 추출시간 120분과 추출온도 <TEX>$16^{\circ}C$</TEX>를 보였다. The purpose of this study was to determine the optimum conditions of solvent extraction type and solvent concentration (60, 70, 80%, v/v), extraction time (30, 80, 130 mins) and extraction temperature (10, 15, <TEX>$20^{\circ}C$</TEX>) in order to increase the antioxidant activity of the chia seed. The total polyphenol content and DPPH radical scavenging activity was measured by using response surface methodology (RSM) to establish the optimal conditions. Using ethanol and methanol extractions at extraction concentrations of 60%, and time and temperature of 130 mins and <TEX>$20^{\circ}C$</TEX>, the maximum total polyphenol content was 871.00 mg% (<TEX>$R^2=0.9507$</TEX>) and 557.70 mg% (<TEX>$R^2=0.9784$</TEX>) for ethanol and methanol extraction respectively. Using the same extraction conditions, the maximum level of DPPH radical scavenging activity was 72.14% (<TEX>$R^2=0.9675$</TEX>) and 52.79% (<TEX>$R^2=0.9524$</TEX>) for ethanol and methanol extraction respectively. The results indicate that ethanol extracts showed a higher antioxidant activity than methanol extracts. The ethanol extraction conditions of response surface analysis (RSA) were affected more by ethanol concentration than by extraction time or temperature. In contrast, the methanol extraction conditions of response surface analysis (RSA) were affected more by extraction time. Based on the RSM, the optimum ethanol extraction conditions were the following: extraction concentration, 63%: time, 100 mins: and temperature, <TEX>$18^{\circ}C$</TEX>. The optimum methanol extraction conditions were the following: extraction concentration, 65%; time, 120 mins; and temperature, <TEX>$16^{\circ}C$</TEX>.

Banana peel contains starch, protein, fat, total fiber, unsaturated fatty acids, pectin, amino acids, polyphenols and micronutrients. Horn banana peelhas many benefits, namely it can be processed into a natural antioxidant material that can minimize banana skin waste. The banana peel extraction method used is Ultrasound Assisted Extraction. Ultrasound Assisted Extraction at optimal conditions produces good levels of total polyphenols with a short extraction time. In the use of ultrasonic no additional chemicals or other materials are needed. This study aims to determine the effect of extraction time (10, 20, 30 minutes), extraction temperature (20, 30, 40℃) and solvent ratio (gr/mL) (1:25, 1:30, 1:35) on polyphenols. The Design Expert V13 program with Response Surface Methodology (RSM) Box-Behnken Design (BBD) was used to determine the combination of extraction parameters that lead to optimal results for total polyphenol content. Based on the research that has been done, it can be stated that the extraction parameters affect the total polyphenol content. The highest total polyphenol content was 61,007 mg GAE/g sample with the extraction conditions at an extraction temperature of 30℃, an extraction time of 30 minutes, and a ratio of banana peel powder to a dissolution of 1:30 g/mL. Keywords : Banana Peel, Polyphenols, Ultrasound Assisted Extraction

Grape seed is a potential source of edible protein, so effective extraction of protein component from grape seed seems to be very important. However, so far, such information is unavailable. In this study, the conditions for protein extraction from the grape seeds were optimized by the single factor test and the response surface methodology (RSM). A box-behnken design (BBD) was used for experimental design and analysis of the results to obtain the optimal extraction conditions. Solvent/meal ratio, extraction temperature, pH and extraction time were found to have a significant effect on the protein yield. From the single factor test, the optimal range of extraction conditions was obtained. Based on the RSM analysis, optimum extraction parameters were obtained as following: solvent/meal ratio 22.5/1 (v/w), extraction temperature 35°C, pH 9.8, and extraction time 29 min. Under the optimized conditions, the experimental values were in good agreement with those predicted by the model. These results help design the process of optimal protein extraction from grape seeds for future use in food industry.

Phillyrin is an abundant naturally occurring lignan, which makes it a potentially important raw material for a precursor of biologically active compounds. The objective of the current study was to optimize the extraction conditions for phillyrin from Forsythia suspensa. The optimum conditions were evaluated with preliminary experiments and optimized using response surface methodology. Statistical analysis of results showed that the linear and quadric terms of these four variables had significant effects, and evident interaction existing between extraction time and extraction temperature was also found to contribute to the response at a significant level. The extraction conditions were further investigated with Box-Behnken design. The fitted second-order model revealed that the optimal conditions consisted of methanol concentration of 21.17%, extraction time 85.43 min, extraction temperature 66.81°C and ratio of liquid to material 11.2. Under the optimized condition, the experimental value of 0.801±0.012 mg/g was well in close agreement with the value predicted by the model. Moreover, the yield of phillyrin in the condition was higher than that of the non-optimized condition. These results help in designing the process of optimal phillyrin from F. suspensa. Key words: Forsythia suspensa, phillyrin, optimum conditions, response surface methodology; box-behnken design.

Optimized microwave-assisted azadirachtin extraction using response surface methodology

Grape seeds are a major by-product of the winemaking industry and a great source of bioactive compounds such as polyphenols and proteins. These compounds have a wide range of applications including those in nutraceutical products and cosmetics and within the wine industry itself. Subcritical water extraction (SWE) was explored as a global method to valorize grape seed by-products for their different bioactive compounds in the context of waste valorization, green chemistry (solvent-free extraction), and circular economy. A Box–Behnken design was applied to generate mathematical responses and the ANOVA analysis determined the optimal extraction conditions (pressure, temperature, and time of extraction) for different responses such as total polyphenol content (TPC), antioxidant activity (AA), and total protein (Tprot). Extraction temperature was found to be the most significant factor influencing all responses while pressure had no significant impact on them. Optimal conditions were derived from the mathematical models for each response. For polyphenol extraction, the optimal conditions were as follows: 170 °C and 20 bar for 39 min with 288 mg GAE/g DM. To achieve the highest AA, SWE parameters should be set at 165 °C and 20 bar for 51 min with 332 mg TROLOX/g DM. For the extraction of proteins, it is necessary to work at 105 °C and 20 bar for 10 min (78 mg BSA/g DM) to preserve protein functionality. In comparison, conventional solvent extraction was unable to outperform SWE with values under the SWE results. Given the high content of polyphenols found in the extracts, an HPLC analysis was conducted. The following compounds were detected and quantified: protocatechuic acid (7.75 mg/g extract), gallic acid (6.63 mg/g extract), delphinidin chloride (1.44 mg/g extract), catechin (0.36 mg/g extract), gentisic acid (0.197 mg/g extract), and some epicatechin (0.07 mg/g extract). Additionally, Maillard reaction products (MRPs) were detected at high temperatures, with 5-hydroxymethylfurfural (5-HMF) appearing in extracts processed at 165 °C and above. The presence of MRPs, known for their antioxidant and bioactive properties, may have contributed to the increased AA observed in these extracts. These findings are significant because a solvent-free extraction process like SWE offers a sustainable approach to repurposing winemaking by-products, with potential applications in the wine and food industries.

Coffee leaves contain various bioactive compounds that are beneficial for human health. However, there are very limited researches related to the extraction of the bioactive phytochemicals from coffee leaves. In the present study, the extraction conditions for bioactive components from coffee leaves were optimized using Taguchi design and response surface methodology (RSM). Taguchi design was used to screen significant factors that affected the yield of phytochemicals including trigonelline, caffeine, chlorogenic acids, mangiferin, and rutin, total phenolic content (TPC) and antioxidant activity. Sequentially, a Box-Behnken design (BBD) was used to optimize the extraction conditions. Three factors including Liquid-to-solid (L:S) ratio, ethanol concentration, and extraction temperature that significantly affected most of the phytochemical yields and antioxidant activity were selected from the six variables using Taguchi design. The optimal extraction conditions obtained from RSM were 30.3:1 L:S ratio, 54.5% ethanol, and 80°C when simultaneously considered four responses, including TPC, the yields of mangiferin and 5-CQA and DPPH scavenging capacity. Under the optimal conditions, the experimental results for the above four responses were 62.1mg gallic acid/g, 4.1mg/g, 11.4mg/g, and 356.9µmol Trolox/g, respectively, which were close to the predicted values. About 97% of phytochemicals can be extracted in the first two times of extraction. In conclusion, the combination of Taguchi design and response surface methodology can be successfully used to screen and optimize the significant factors that affected the bioactive components extracted from coffee leaves. PRACTICAL APPLICATION: Coffee leaves, the byproducts of coffee plants, are considered no- or low-value although it has a long history for using them as tea-like beverage and ethnomedicine by locals in the coffee plant growing countries. Bioactive components extracted from coffee leaves can be used as ingredients in functional beverages, functional food, and natural health products. These applications will add values to coffee leaves as well as increase the incomes of coffee farmers and workers.

The efficient extraction of polyphenols from pomegranate peels using a deep eutectic solvent (DES) and ultrasound-assisted extraction (UAE) was investigated. A Box-Behnken design was used to investigate the effects of four independent variables (water content, liquid-to-solid ratio, ultrasonic power, and extraction time) on total polyphenol content (TPC), punicalagin content (PC), and ellagic acid content (EC). Optimized DES-based UAE conditions were as follows: TPC (water content, 29.30%; liquid-to-solid ratio, 53.50 mL/g; ultrasonic power, 238.20W; extraction time, 29.50min), PC (water content, 25.65%; liquid-to-solid ratio, 44.20 mL/g; ultrasonic power, 120W; extraction time, 20min), and EC (water content, 33.13%; liquid-to-solid ratio, 60 mL/g; ultrasonic power, 300W; extraction time, 20min). Under these optimal conditions, the experimental values for TPC, PC, and EC were 67.50mg GAE/g, 130.65mg/g, and 2.04mg/g, respectively; these values were consistent with the predicted values.

Many studies have explored the extraction of bioactive compounds from different onion solid wastes, such as bulb, skin, and peel. However, onion leaves have received limited attention despite their potential as a valuable source of nutraceutical compounds. This study aimed to valorise, for the first time, the agricultural waste in the form of spring onion leaves (CN, Cipollotto Nocerino) to obtain antioxidant-rich polyphenolic extracts. A Box–Behnken design (BBD) was used to assess the impact of microwave-assisted extraction (MAE) variables (temperature, time, extraction volume, and ethanol concentration) on total polyphenol content (TPC) measured by Folin–Ciocalteu method and the antioxidant power determined by FRAP assay. Response surface methodology (RSM) was applied, and regression equations, analysis of variance, and 3D response curves were developed. Our results highlighted that the TPC values range from 0.76 to 1.43 mg GAE g−1 dw, while the FRAP values range from 8.25 to 14.80 mmol Fe(II)E g−1 dw. The optimal extraction conditions predicted by the model were 60 °C, 22 min, ethanol concentration 51% (v/v), and solvent volume 11 mL. These conditions resulted in TPC and FRAP values of 1.35 mg GAE g−1 dw and 14.02 mmol Fe(II)E g−1 dw, respectively. Furthermore, the extract obtained under optimized conditions was characterized by UHPLC-ESI-Orbitrap-MS analysis. LC/MS–MS platform allowed us to tentatively identify various compounds belonging to the class of flavonoids, saponins, fatty acids, and lipids. Finally, the ability of CN optimal extract to inhibit the intracellular reactive oxygen species (ROS) release in a hepatocarcinoma cell line using an H2O2-induced oxidative stress model, was evaluated. The results highlighted the potential of CN extract as a valuable source of polyphenols with significant antioxidant properties, suitable for various applications in the food and pharmaceutical industries.