MODEL DEVELOPMENT AND PROCESS OPTIMIZATION FOR SOLVENT EXTRACTION OF POLYPHENOLS FROM RED GRAPES USING BOX–BEHNKEN DESIGN

Optimization of Surfactant-Mediated Green Extraction of Phenolic Compounds from Grape Pomace Using Response Surface Methodology

Grape pomace is a by-product abundant in phenolic compounds that can be used in the food, cosmetic, and pharmaceutical industries. For the efficient extraction of such compounds, an aqueous solution of non-ionic surfactant Brij S20 was applied as a green extraction medium, and the optimization was performed using surface response methodology. The effects of four independent factors (surfactant concentration, time, pH, and solvent-to-material ratio) were evaluated, and total phenolic content (TPC), DPPH radical inhibition, and selected polyphenol compound concentrations were analyzed as responses. Using response surface methodology (RSM), five regression equations were derived and good adequacy of the models was confirmed. The solvent-to-material (SM) ratio was the most influential factor. Surfactant concentration of 3% (m/V), extraction time of 120 min, pH value of 4.06, and SM ratio of 50 mL/g were determined as optimum conditions to maximize all responses. Under the optimal conditions, the mean validated values obtained for TPC, DPPH, gallic acid, catechin, and quercetin concentrations were 968.50 ± 37.06 mg GAE/L, 61.41 ± 7.13%, 5.10 ± 0.05 mg/L, 10.62 ± 0.79 mg/L, and 6.04 ± 0.10 mg/L, respectively. Furthermore, the established conditions were applied for the extraction of phenolic compounds from grape pomace of four grape varieties. The proposed extraction method proved effective, providing extracts rich in polyphenols suitable for further applications.

Exploring new approach for resource utilization of crab shell waste: Optimized microwave torrefaction parameters and efficient self-desulfurization

Finding alternative energy sources and reducing the impact of waste on the environment are pressing global challenges. Crab shells possess the dual characteristics of a pollutant and a resource; therefore, transforming them into clean energy is an urgent issue that needs to be addressed for reducing environmental pollution. This study uses microwave torrefaction to treat crab shell waste efficiently and optimizes the torrefaction conditions through response surface methodology to rapid prepare derived fuel. At a microwave power of 2500 W, temperature of 225 °C, and a treatment duration of 11 min, the specific surface area of the crab shell derived fuel increased by 21.2%; furthermore, its high heating value increased from 14.41 to 18.18 MJ/kg and combustion and desulfurization performances improved considerably. As a proof-of-concept, these derived fuels were utilized as substitutes for fossil fuels and as desulfurization agents to capture SO2 in situ during coal combustion. Results indicated that after microwave torrefaction, the desulfurization capability of the crab shell derived fuel increased by 16.6%. At a derived fuel and coal blending ratio of 35%, SO2 emissions were reduced by 85.27%, with more desulfurization efficiency compared with conventional calcium-based dry desulfurization. To the best of our knowledge, this is the first report on using crab shell waste as derived fuel to achieve in situ SO2 capture. Given the low cost and renewability of crab shell, our study provides a promising strategy for the large-scale utilization of solid waste and its harmless disposal.

A Novel Bioflocculant Produced by Cobetia marina MCCC1113: Optimization of Fermentation Conditions by Response Surface Methodology and Evaluation of Flocculation Performance when Harvesting Microalgae

A preliminary study was carried out to optimize the culture medium conditions for producing a novel microbial flocculant from the marine bacterial species Cobetia marina. The optimal glucose, yeast extract, and glutamate contents were 30, 10, and 2 g/l, respectively, while the optimal initial pH of the culture medium was determined to be 8. Following response surface optimization, the maximum bioflocculant production level of 1.36 g/l was achieved, which was 43.40% higher than the original culture medium. Within 5 min, a 20.0% (v/v) dosage of the yielded bioflocculant applied to algal cultures resulted in the highest flocculating efficiency of 93.9% with Spirulina platensis. The bioflocculant from C. marina MCCC1113 may have promising application potential for highly productive microalgae collection, according to the findings of this study.

Effect of Temperatures on Polyphenols during Extraction

Background: Polyphenols are a set of bioactive compounds commonly found in plants. These compounds are of great interest, as they have shown high antioxidant power and are correlated to many health benefits. Hence, traditional methods of extraction such as solvent extraction, Soxhlet extraction and novel extraction technologies such as ultrasound-assisted extraction and subcritical water extraction (SWE) have been investigated for the extraction of polyphenols. Scope and Approach: Generally, for traditional extractions, the total phenolic content (TPC) is highest at an extraction temperature of 60–80 °C. For this reason, polyphenols are regularly regarded as heat-labile compounds. However, in many studies that investigated the optimal temperature for subcritical water extraction (SWE), temperatures as high as 100–200 °C have been reported. These SWE extractions showed extremely high yields and antioxidant capacities at these temperatures. This paper aimed to examine the relevant literature to identify and understand the mechanisms behind this discrepancy. Results: Thermal degradation is the most common explanation for the degradation of polyphenols. This may be the case for specific or sub-groups of phenolic acids. The different extraction temperatures may have also impacted the types of polyphenols extracted. At high extraction temperatures, the formation of new compounds known as Maillard reaction products may also influence the extracted polyphenols. The selection of source material for extraction, i.e., the plant matrix, and the effect of extraction conditions, i.e., oxidation and light exposure, are also discussed. The overestimation of total phenolic content by the Folin–Ciocâlteu assay is also discussed. There is also a lack of consensus in TPC’s correlation to antioxidant activity.

Modeling the influence of extraction parameters on the yield and chemical characteristics of microwave extracted mango (Mangifera indica L.) peel pectin by response surface methodology

Extraction is considered to be a critical unit operation to recover bioactive compounds from the in-situ state of many plant-based food processing wastes. The characteristics of pectin were predicted to vary with the source of raw material, extraction and post-extraction conditions. The study was focused to investigate the optimal conditions for extracting mango peel pectin (MPP) with increased yield and quality by microwave-assisted extraction (MAE). Box Behnken experimental design was used to model the influence of extraction parameters (microwave power, pH, and time) on the responses (yield, esterification degree, equivalent weight, anhydrouronic acid, and methoxyl content of pectin). The predicted models were adequately fitted to the experimental data (p ≤ 0.001) for all the response variables. A higher yield of pectin with better quality was obtained with optimal conditions of microwave power 606 watts (W), extraction time 5.15 min, and pH 1.83. The MPP obtained is categorized as low-methoxyl pectin as the range for the degree of esterification (DE) at all possible treatment variations remained below 50%. The study revealed that mango peel was an effective alternative source of pectin which could be extracted by microwave method on large scale.

Optimization of electrocoagulation process parameters for enhancing phosphate removal in a biofilm-electrocoagulation system

This study aimed to enhance the removal of phosphate in synthetic rural sewage by using a continuous electrocoagulation (EC) combined with biofilm process in an integrated system. Characteristic indexes of biofilm process effluent covering pH, dissolved oxygen (DO), suspended solids (SS), chemical oxygen demand (COD) and phosphate maintained a narrow fluctuation range and tended not readily to influence the phosphate removal of subsequent electrocoagulation. Three parameters including inter-electrode distance, current intensity and reaction time were selected to investigate the performance of enhancing phosphate removal. On the strength of single-factor tests, the Box-Behnken design (BBD) coupled with response surface methodology (RSM) was applied to investigate the individual and mutual interaction impacts of the major operating parameters and to optimize conditions. The optimum conditions were found to be inter-electrode distance of 1.8 cm, current density of 2.1 mA/cm² and EC reaction time of 34 min, and phosphate removal efficiency of 90.24% was achieved along with less than 1 mg/L in case of periodic polarity switching mode, which raised removal efficiency by 10.10% and reduced operating cost by 0.13 CNY/g PO₄^- compared to non-switching mode. The combination of biofilm processing and electrocoagulation treatment was proven to be a valid and feasible method for enhancing phosphate removal.

Optimization of Chitosan-Alginate Microparticles for Delivery of Mangostins to the Colon Area Using Box-Behnken Experimental Design

Chitosan-alginate microparticles loaded with hydrophobic mangostins present in the mangosteen rind extract have been formulated and optimized for colon-targeted bioactive drug delivery systems. The chitosan–mangostin microparticles were prepared using the ionotropic gelation method with sodium tripolyphosphate as the cross-linking agent of chitosan. The chitosan–mangostin microparticles were then encapsulated in alginate with calcium chloride as the linking agent. The mangostin release profile was optimized using the Box–Behnken design for response surface methodology with three independent variables: (A) chitosan–mangostin microparticle size, (B) alginate:chitosan mass ratio, and (C) concentration of calcium chloride. The following representative equation was obtained: percent cumulative release of mangostins (10 h) = 59.51 − 5.16A + 20.00B − 1.27C − 1.70AB − 5.43AC − 5.04BC + 0.0579A² + 10.25B² + 1.10C². Cumulative release of 97% was obtained under the following optimum condition for microparticle preparation: chitosan–mangosteen particle size < 100 µm, alginate:chitosan mass ratio of 0.5, and calcium chloride concentration of 4% w/v. The alginate to chitosan mass ratio is the statistically significant variable in the optimization of sequential release profile of mangostins in simulated gastrointestinal fluids. Furthermore, a sufficient amount of alginate is necessary to modify the chitosan microparticles and to achieve a complete release of mangostins. The results of this work indicate that the complete release of mangostins to the colon area can be achieved using the chitosan–alginate microparticles as the bioactive delivery system.

Optimization of Bioactive Substances in the Wastes of Some Selective Mediterranean Crops

Production of added products from industrial byproducts is a challenge for the current natural product industry and the extraction field more generally. Therefore, the aim of this study is to valorize the selected Mediterranean crops that can be applied as antioxidants, natural chelating agents, or even as biosolvents or biofuels after special treatment. In this study, the wastes of popular Mediterranean plants were extracted via homogenizer-assisted extraction (HAE) by applying response surface methodology (RSM) to examine the effects of process parameters on the total biophenolic contents (TBCs) of their residues. Box–Behnken design model equations calculated for each system were found significant (p < 0.0001) with an adequate value of determination coefficient (R2). Olive leaf had the highest TBC content (58.62 mg-GAE/g-DW with 0.1 g sample, 42.5% ethanol at 6522.2 rpm for 2 min), followed by mandarin peel (27.79 mg-GAE/g-DW with 0.1 g sample, 34.24% ethanol at 8772 rpm for 1.99 min), grapefruit peel (21.12 mg-GAE/g-DW with 0.1 g sample, 42.33% ethanol at 5000 rpm for 1.125 min) and lemon peel (16.89 mg-GAE/g-DW with 0.1 g sample, 33.62% ethanol at 5007 rpm for 1.282 min). The antioxidant activities of the extracts were measured by several in vitro studies. The most prominent biophenols of the wastes were quantified by high performance liquid chromatography (HPLC). Fourier-transform infrared-attenuated total reflectance (FTIR-ATR) and atomic force microscopy (AFM) techniques were also used for characterization.

Simultaneous Quantification of Seven Bioactive Flavonoids in Citri Reticulatae Pericarpium by Ultra-Fast Liquid Chromatography Coupled with Tandem Mass Spectrometry

INTRODUCTION

Citri Reticulatae Pericarpium (CRP) is a commonly-used traditional Chinese medicine with flavonoids as the major bioactive components. Nevertheless, the contents of the flavonoids in CRP of different sources may significantly vary affecting their therapeutic effects. Thus, the setting up of a reliable and comprehensive quality assessment method for flavonoids in CRP is necessary.

OBJECTIVE

To set up a rapid and sensitive ultra-fast liquid chromatography coupled with tandem mass spectrometry (UFLC-MS/MS) method for simultaneous quantification of seven bioactive flavonoids in CRP.

METHODS

A UFLC-MS/MS method coupled to ultrasound-assisted extraction was developed for simultaneous separation and quantification of seven flavonoids including hesperidin, neohesperidin, naringin, narirutin, tangeretin, nobiletin and sinensetin in 16 batches of CRP samples from different sources in China.

RESULTS

The established method showed good linearity for all analytes with correlation coefficient (R) over 0.9980, together with satisfactory accuracy, precision and reproducibility. Furthermore, the recoveries at the three spiked levels were higher than 89.71% with relative standard deviations (RSDs) lower than 5.19%. The results indicated that the contents of seven bioactive flavonoids in CRP varied significantly among different sources. Among the samples under study, hesperidin showed the highest contents in 16 samples ranged from 27.50 to 86.30 mg/g, the contents of hesperidin in CRP-15 and CRP-9 were 27.50 and 86.30 mg/g, respectively, while, the amount of narirutin was too low to be measured in some samples.

CONCLUSION

This study revealed that the developed UFLC-MS/MS method was simple, sensitive and reliable for simultaneous quantification of multi-components in CRP with potential perspective for quality control of complex matrices. Copyright © 2016 John Wiley & Sons, Ltd.

Optimization of Betulinic Acid Extraction from Tecomella undulata Bark Using a Box-Behnken Design and Its Densitometric Validation

Betulinic acid (BA) is a pentacyclic triterpenoid acid obtained from the stem bark of Tecomella undulata Seem. (Bignoniaceae). Development of an efficient extraction method for the isolation of BA is important as it has a wide range of pharmacological activity. A Box-Behnken design (BBD) was used to investigate the effect of extraction variables such as temperature (30-60 °C), time (4-8 h) and solvent to drug ratio (300-500 mL/100 g) on the maximization of BA yield and its quantification using validated densitometric high performance thin layer chromatography coupled with ultraviolet detection (HPTLC-VIS). A quadratic polynomial model was found to best fit the model with R² = 0.99. The optimized Soxhlet extraction yielded 2.449% w/w of BA at a temperature 53.86 °C, time 6.38 h and solvent to drug ratio 371 mL/100 g. BA in Tecomella undulata bark was detected at Rf value of 0.65 at 510 nm using the solvent system toluene-ethyl acetate-glacial acetic acid (8.5:1.5:0.02 v/v/v). The analytical method was validated and the linear regression analysis reflects good linear relationship (R² = 0.9902). Lower %RSD and SEM suggested that the developed HPTLC-VIS method was precise, accurate and robust. Therefore, these economical techniques are very efficient and promising for the extraction and quantification of pharmaceutically important BA.

Revealing the characteristics of a novel bioflocculant and its flocculation performance in Microcystis aeruginosa removal

In the present work, a novel bioflocculant, EPS-1, was prepared and used to flocculate the kaolin suspension and Microcystis aeruginosa. We focused on the characteristics and flocculation performance of EPS-1, especially with regard to its protein components. An important attribute of EPS-1 was its protein content, with 18 protein types identified that occupied a total content of 31.70% in the EPS-1. Moreover, the flocculating activity of these protein components was estimated to be no less than 33.93%. Additionally, polysaccharides that occupied 57.12% of the total EPS-1 content consisted of four monosaccharides: maltose, D-xylose, mannose, and D-fructose. In addition, carbonyl, amino, and hydroxyl groups were identified as the main functional groups. Three main elements, namely C1s, N1s, and O1s, were present in EPS-1 with relative atomic percentages of 62.63%, 24.91%, and 10.5%, respectively. Zeta potential analysis indicated that charge neutralization contributed to kaolin flocculation, but was not involved in M. aeruginosa flocculation. The flocculation conditions of EPS-1 were optimized, and the maximum flocculating efficiencies were 93.34% within 2 min for kaolin suspension and 87.98% within 10 min for M. aeruginosa. These results suggest that EPS-1 could be an alternative to chemical flocculants for treating wastewaters and cyanobacterium-polluted freshwater.

Preparation of a new-style composite containing a key bioflocculant produced by Pseudomonas aeruginosa ZJU1 and its flocculating effect on harmful algal blooms

A novel composite consisting of clay, bioflocculant, and inorganic flocculant was designed, and its flocculating effect on harmful algal blooms (HABs) was studied in this study. The extracellular polymeric substances (EPS), produced with a yield of 3.58±0.11 g/L by a newly isolated Pseudomonas aeruginosa ZJU1, was indicated to be a key component in the composite. The components and functional groups of the EPS were analyzed, and it showed that polysaccharides, proteins, and nucleic acids are the main components; polar functional groups in the EPS are responsible for its flocculating activity. The novel composite was optimized by the response surface methodology and after optimization, the optical components and contents of the composite were Kaolin 2.38 g/L, CaCl2 0.28 g/L, KAl(SO4)2 0.09 g/L, and EPS 1.75 mg/L. The flocculating rates of the composite were tested, and it could rapidly reach 100±0.13% within 2 min when OD680 of Microcystis aeruginosa was 0.1; it could reach 100±0.08% within 5 min for OD680 of M. aeruginosa in HABs up to 1.0. These results suggest that the novel composite will be a highly efficient material for the treatment of HABs caused by M. aeruginosa.

Modeling and optimization of supercritical fluid extraction of anthocyanin and phenolic compounds from Syzygium cumini fruit pulp

Supercritical carbon dioxide extraction (SC-CO2) of total anthocyanin and phenolic compounds from jamun fruits was investigated using three factors at three levels Box-Behnken response surface design. Experiments were conducted to evaluate the effects of three independent variables (pressure, temperature and co-solvent flow rate) on the maximum extraction yield of anthocyanin and phenolic compounds from jamun fruits. From the experimental data, second order polynomial mathematical models were developed with high coefficient of determination values (R (2) > 0.98). From response surface plots, pressure, temperature and co-solvent flow rate exhibited independent and interactive effects on the extraction yields. Pressure of 162 bar, extraction temperature at 50 °C and co-solvent flow rate of 2.0 g/min was identified as optimal conditions. Under these optimal conditions, the experimental value agreed well with the predicted values and indicates the suitability of developed models.