Enhanced Polysaccharide Extraction from Chlorella pyrenoidosa Using Microwave-Assisted Technique and Response Surface Methodology Approach

The growing popularity of integration of functional compounds into food and pharmaceutical products has greatly influenced the intense investigation of aromatic plants as its notable sources. One of the insufficiently explored plant species—Mountain Germander (Teucrium montanum)—may represent a prominent source of biologically active components—polyphenols. Hence, to maximally enhance their recovery, conventional (HAE) and non-thermal extraction methods—microwave-assisted extraction (MAE) and subcritical water extraction (SWE) were employed by using multiple response surface methodology (RSM). Optimization of temperature, solid-to-solvent ratio, and extraction time was evaluated by measuring total phenolic content (TPC) and antioxidant capacity (DPPH and ABTS assays), with the further estimation of the extraction efficiency of two selected phenylethanoid glycosides present in final extracts—verbascoside and echinacoside determined by HPLC analysis. The optimum HAE, MAE, and SWE extraction conditions with the highest measured dependent variables were, as follows: 100 °C, 0.5 g/50 mL and 30 min, 90 °C, 0.5 g/50 mL and 9 min, 200 °C, 0.5 g/50 mL and 15 min, respectively. Regarding examined phenylethanoid glycosides, HAE extract showed to be its richest source (16.64 mg/g dw) while SWE was estimated as at least suitable extraction technique (5.42 mg/g dw). In conclusion, this study outlined the most appropriate extraction technique and conditions for the recovery of selected phenolic compounds using RSM and gave closely insight into the antioxidative potential of valuable ethnomedicinal plant from the Balkan peninsula—Teucrium montanum

The partitioning and purification of lectins from the crude extract of Cratylia mollis seeds (Cramoll 1,4) was investigated in aqueous two-phase systems (ATPS). A factorial design model (24) was used to evaluate the influence of polyethylene glycol (PEG) molar mass (1500–8000 g/mol), PEG concentration (12.5–17.5% w/w), phosphate (10–15% w/w) concentration, and pH (6–8) on the differential partitioning, purification factor, and yield of the lectin. Polymer and salt concentration were the most important variables affecting partition of lectin and used to find optimum purification factor by experimental Box–Behnken design together with the response surface methodology (RSM). ATPS showed best conditions composed by 13.9% PEG1500, 15.3% phosphate buffer at pH 6, which ensured purification factor of 4.70. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis showed a single band of protein with 26.1 kDa. Furthermore, results demonstrated a thermostable lectin presenting activity until 60 °C and lost hemagglutinating activity at 80 °C. According to the obtained data it can be inferred that the ATPS optimization using RSM approach can be applied for recovery and purification of lectins.

This research work was carried out to explore the influence of extraction methods on the extraction of antioxidant from Asparagus racemosus roots. The microwave‐assisted extraction (MAE) method was more efficient as compared with continuous shaking extraction (CSE) method in terms of total phenolic content (TPC), total flavonoids content (TFC), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and total antioxidant capacity (TAC) content in the ethanolic extract of A. racemosus roots. Box–Behnken experimental design of response surface methodology (RSM) was used to optimize MAE method for three process parameters viz. solvent concentration (SC: 40%–90% v/v), extraction time (ET: 10–30 min), and microwave power (MP: 360–720 W). Model fitness of the experimental data was determined by multiple regression analysis and analysis of variance. The optimum targeted parameters were obtained as 65% v/v SC, 23 min ET, and 560 W MP, and the corresponding responses TPC, TFC, DPPH, FRAP, and TAC were found to be 9.377 mg GAE/g, 177.03 mg QE/g, 65.70%, 193.35 mM Fe+2/g, and 496.97 mg AAE/g with a desirability of 0.95. Fuzzy modeling with Mamdani‐type fuzzy inference was also utilized to obtain the most optimal conditions for specified process parameters and responses under the set of rules for process parameters and responses. The estimated results of responses by both RSM and fuzzy model showed good agreement with the experimental values.

Today, the principles of green chemistry are being fundamentally applied in the chemical industry, such as the nitrobenzene industry, which is an essential intermediate for various commercial products.Research on the application of response surface methodology (RSM) to optimize nitrobenzene synthesis was conducted using a sulfated silica (SO 4 /SiO 2 ) catalyst and batch microwave reactor.The nitrobenzene synthesis process was carried out according to RSM using a central composite design (CCD) design for three independent variables, consisting of sulfuric acid concentration on the silica (%), stirring time (min), and reaction temperature (C), and the response variable of nitrobenzene yield (%).The results showed that a three-factorial design using the response surface method could determine the optimum conditions for obtaining nitrobenzene products in a batch microwave reactor.The optimum condition for a nitrobenzene yield of 63.38 % can be obtained at a sulfuric acid concentration on the silica of 91.20 %, stirring time of 140.45 min, and reaction temperature of 58.14 C.From the 20 experiments conducted, the SO 4 /SiO 2 catalyst showed a selectivity of 100 %, which means that this solid acid catalyst can potentially work well in converting benzene to nitrobenzene.

Evaluation of microwave-assisted and pressurized liquid extractions to obtain β-d-glucans from mushrooms

High-intensity ultrasound-assisted extraction was used to extract total soluble phenols, flavonoids, and anthocyanins from Beta vulgaris stems, and to evaluate their antioxidant activities (DPPH, ABTS, and FRAP). The effect of extraction time (X1: 2, 4, and 6 min), ultrasound power (X2: 80%, 90% and 100%), and liquid-to-solid ratio (X3: 10:1, 15:1, and 20:1 mL/g) was investigated using response surface methodology. The high-intensity ultrasound-assisted extraction models for all responses were adjusted to a 2nd-order polynomial equation (R2 = 0.94 - 0.99, lack of fit > 0.05). Optimal high-intensity ultrasound-assisted extraction conditions differ for each response, X1: 3.08 min, X2: 100%, and X3: 17.32:1 mL/g for total soluble phenols, X1: 5.99 min, X2: 95.04% and X3: 17.28:1 mL/g for total flavonoids, and X1: 6 min, X2: 92.24%, and X3: 12.97:1 mL/g for total anthocyanins. Moreover, all evaluated conditions exhibited antioxidant properties by DPPH, ABTS, and FRAP. Furthermore, the validated high-intensity ultrasound-assisted extraction conditions (3.08 min for extraction time, 100% power ultrasound, and 17.32 mL/g of liquid-to-solid ratio) yielded 2.35 times higher soluble phenols content than conventional extraction method (magnetic stirring at 400 rpm for 60 min), with higher (p ˂ 0.05) flavonoids, ABTS, and FRAP values, and similar values (p > 0.05) for anthocyanins and DPPH. Furthermore, shikimic, protocatechuic, 4-hydroxybenzoic, gallic, chlorogenic, neochlorogenic, and trans-ferulic acids were higher under high-intensity ultrasound-assisted extraction than conventional extraction according to the HPLC analysis. It demonstrated that high-intensity ultrasound-assisted extraction is an efficacious technology for extracting bioactive molecules. In addition, future research could focus on isolating and purifying the phenolic compounds extracted from B. vulgaris stem powder, which have potential applications in food and non-food industries. HIGHLIGHTS Beta vulgaris stems are a source of phytochemicals Ultrasound is a viable technology for extracting bioactive compounds Beta vulgaris extracts exhibited antioxidant properties GRAPHICAL ABSTRACT

Utilization of sage by-products as raw material for antioxidants recovery—Ultrasound versus microwave-assisted extraction

In the present work, the response surface methodology (RSM) approach has been used to investigate the mechanism of interface slip damping in layered tack-welded structures with varying surface roughness. Many experiments have been conducted on a number of mild steel specimens with various roughness conditions at the interfaces to study their effect on the damping capacity of the layered and jointed welded structures. The response is modeled using the RSM approach on experimental data. The significant coefficients are obtained by performing the analysis of variance at a 5% level of significance. The natural frequency and amplitude of excitation, kinematic coefficient of friction, surface roughness and relative dynamic slip at the interfaces have been observed to play vital roles on the damping capacity of such structures. The model sufficiency has been found to be satisfactory as the coefficient of determination (R2) and adjusted R2-statistic (R2adj) are found to be 96.9% and 96.8%, respectively.

The aim of the study was to optimized cyclodextrin glycosyltransferase (CGTase) production using local isolated strain MK6 which was identified as Bacillus sp. Optimum activity obtained at temperature of 70 °C and the enzyme shows a wide range of pH stability ranging from 4-10 when stored at 4 °C for 24 h and temperature stability ranging from 30-80 °C at 1 h incubation period. The CGTase activity was even maintained at 0.4 U mL-1 at 90 °C for 40 min incubation. Prior to optimization of CGTase production, selection for the best carbon source through detection using modified phenolphthalein method containing different types of starch were performed. Sago starch gave significant result and was used for further optimization using statistical analysis namely Response Surface Methodology (RSM) approach. The optimal calculated values were 3.34% sago starch, initial pH of 10.15 and agitation speed of 187 rpm; with predicted activity of 2.07 U mL-1 of CGTase. These predicted optimal parameters were confirmed in the laboratory and the final CGTase activity obtained was very close to the predicted value of 2.56 U mL-1.

The focus on ammonium hydroxide, biodiesels and their combustion technology has garnered significant attention in pursuing carbon-neutral and carbon-free fuels to address greenhouse gas emissions (GHG) and mitigate global warming. Low-temperature combustion (LTC) has been introduced as an alternative method to conventional compression ignition (CI) combustion. Reactivity controlled compression ignition (RCCI) can be achieved by introducing highly reactive waste cooking oil methyl ester (WCOME) oil directly into the manifold in intervals of 10% energy and injecting low-reactive ammonium hydroxide at 20%–50%. Utilizing the response surface methodology (RSM) approach, it was determined that for optimal operation in RCCI mode, an ideal ammonium hydroxide energy sharing (AHES) of 43% would account for the varying parameters and their effects on emissions and performance. The results of the experiments predicted a brake thermal efficiency (BTHE) of 34.85% and a brake specific energy consumption (BSEC) of 10.69 MJ/kWh. Meanwhile, a notable decrease in exhaust emissions was observed for HC, CO, CO 2 , NO x and smoke by 41.54%, 38.89%, 48.89%, 51.27% and 65.80% respectively when compared to conventional biodiesel combustion (CBC). The experimental result at maximum load operation with an AHES of 50% indicates that RCCI combustion led to an increase in thermal efficiency from 30.36% to 35.42%, and the in-cylinder pressure and heat release rate dropped from 83.42 bar to 59.64 bar and 78.68 kJ to 60.92 kJ, respectively. There was a significant reduction in HC, CO, CO 2 , NO x and smoke emissions recorded as 58.76 ppm, 0.11%v, 1.61%v, 442 ppm and 6.64 N, respectively, compared to CBC.

We successfully extracted isoliquiritigenin from Glycyrrhiza uralensis via fermentation with Aspergillus niger and ultrasonic-assisted extraction. In brief, we used A. niger fermentation to culture G. uralensis powder, and we optimized some key parameters such as reaction conditions of pH, inoculation concentration of A. niger, fermentation time, and solid-liquid ratio. Based on a single-factor experiment, we utilized the response surface methodology (RSM) approach to optimize this extraction procedure. Using the RSM approach, optimized conditions of pH = 3.694, the solid-liquid ratio = 1 : 2.155, and the inoculation concentration of A. niger = 1466745 were selected. Optimized conditions resulted in an extraction efficiency of 1.525 mg/g. These results showed that the extraction of isoliquiritigenin was most affected by pH and then the time of fermentation and the solid-liquid ratio. Overall, the developed extraction technique yielded 5 times the amount of isoliquiritigenin when compared to traditional methods.

Optimization of microwave-assisted carbohydrate extraction from indigenous Scenedesmus sp. grown in brewery effluent using response surface methodology

Microwave-assisted aqueous two-phase extraction of isoflavonoids from Dalbergia odorifera T. Chen leaves

A central composite design combined with response surface methodology was utilized to optimise microwave-assisted extraction of flavonoids from young barley leaves. The results showed that using water as solvent, the optimum conditions of microwave-assisted extraction were extracted twice at 1.27 W g−1microwave power and liquid-solid ratio 34.02 ml g−1for 11.12 min. The maximum extraction yield of flavonoids (rutin equivalents) was 80.78±0.52%. Compared with conventional extraction method, the microwave-assisted extraction was more efficient as the extraction time was only 6.18% of conventional extraction, but the extraction yield of flavonoids was increased by 5.47%. The main flavonoid components from the young barley leaf extract were probably 33.36% of isoorientin-7-O-glueoside and 54.17% of isovitexin-7-O-glucoside, based on the HPLC-MS analysis. The barley leaf extract exhibited strong reducing power as well as the DPPH radical scavenging capacity.

Microwave-assisted extraction (MAE) has emerged as an efficient extraction technique for various kinds of biological samples due to its low usage of extraction solvents and shorter extraction time. This review will focus on the recent developments and advantages of incorporating MAE in sample preparation protocols for the analysis of small molecules in plant, food and clinical samples in recent years. The operating principles of this technique and the key parameters influencing its extraction efficiency, including the nature of solvent, temperature, power and extraction time and their limitations are first mentioned. This is followed by a discussion on the advantages of applying MAE to extract organic contaminants in food for routine food safety analysis and active ingredients recovery. The successful application of MAE technique to recover bioactive compounds from plants in drug discovery studies and quality control purposes is then described. Additionally, the feasibility of using green solvents such as water, micelle and ionic liquids with MAE for plant metabolite profiling studies is evaluated and the associated challenges discussed. Finally, the application of MAE in clinical samples is highlighted. The use of MAE in this field is currently limited to the targeted detection of small molecules in human samples, due to a lack of knowledge of its effects on thermally labile metabolites. Consequently, the need for additional studies on how MAE impacts the recoveries of different metabolite classes in mammalian samples is discussed. The outcome of these studies can potentially broaden MAE applications in the clinical field.