Two-factor Central Composite Design Research Articles

A Phytochemical Approach to the Removal of Contaminants from Industrial Dyeing Wastewater

This study investigates the influence of photoperiod and wastewater concentration on the growth of microalgae and cyanobacteria for the removal of environmentally significant parameters (COD, BOD, Cr, Fe, color, chlorides, nitrogen compounds, and phosphates) from dyeing wastewater. A two-factor central composite design with surface response was employed, involving two algae species (Chlorella and Scenedesmus sp.) and two cyanobacteria species (Hapalosiphon and Oscillatoria sp.). The findings indicated that extended photoperiods (>13 h) and higher wastewater concentrations (70–80% v/v) enhanced biomass production across all strains. However, Hapalosiphon and Chlorella sp. (1.6 and 0.45 g/L) exhibited better tolerance to the wastewater’s high toxicity, resulting in higher biomass concentrations and improved COD and BOD removal by Hapalosiphon sp. (75% and 80%, respectively). Further analysis of the obtained biomass revealed their potential applications. Among the cyanobacteria, Hapalosiphon sp. synthesized the highest concentrations of total proteins and lipids (38% and 28% w/w, respectively), while Oscillatoria sp. displayed a high protein content (42% w/w). In contrast, the algae demonstrated a strong propensity for storing substantial quantities of total carbohydrates (65% and 57% w/w for Scenedesmus and Chlorella sp., respectively). These results signify the feasibility of cultivating photosynthetic microorganisms in industrial dyeing wastewater as a sustainable source of nutrients for targeted metabolite production.

Optimizing Food Processing through a New Approach to Response Surface Methodology.

In a previous study, 'response surface methodology (RSM) using a fullest balanced model' was proposed to improve the optimization of food processing when a standard second-order model has a significant lack of fit. However, that methodology can be used when each factor of the experimental design has five levels. In response surface experiments for optimization, not only five-level designs, but also three-level designs are used. Therefore, the present study aimed to improve the optimization of food processing when the experimental factors have three levels through a new approach to RSM. This approach employs three-step modeling based on a second-order model, a balanced higher-order model, and a balanced highest-order model. The dataset from the experimental data in a three-level, two-factor central composite design in a previous research was used to illustrate three-step modeling and the subsequent optimization. The proposed approach to RSM predicted improved results of optimization, which are different from the predicted optimization results in the previous research.

D-optimal mixture design optimized solid formulation containing fruits extracts of Momordica charantia and Abelmoschus esculentus.

Fruit extracts of Momordica charantia L. (Cucurbitaceae) and Abelmoschus esculentus (L.) Moench (Malvaceae) have shown promising antidiabetic activities in clinical trials. However, they remain underutilized due to insufficient standardization and lack of formulation containing their mixture. This study’s overall purpose was to develop and optimize a capsule dosage form containing dried fruit extracts of M. charantia and A. esculentus. The design of the experiment involved two steps; first, response surface methodology (RSM) with a five-level two-factor central composite rotatable design (CCRD) was employed to determine the optimal dose of a mixture of extracts for adequate glycemic control. The extract of M. charantia and A. esculentus were the independent variables while fasting plasma glucose (FPG) was the dependent factor. In the second step, a D-optimal mixture design was applied to study the interaction effect of the optimal dose and selected excipients on granules flowability and capsules’ disintegration time. Moreover, a second-order quadratic model determined the interrelationship of excipients and the desired capsules’ quality attributes. The validity of the predicted models was confirmed. The findings indicated that a combined dose of 175 A. esculentus and 281 M. charantia (mg/kg) significantly reduced the FPG level compared to vehicle at day 14 (mean difference -2.7 ± 0.21, p < 0.001). This dose was used to make a 600 mg capsule (DM083) with 76% drug loading. The DM083 had 40.4 ± 0.62 mg GAE/gDW total polyphenols, 12 peaks HPLC fingerprint, and 26.6 ± 4.75 min average disintegration time. Together, these findings showed that a mixture of M. charantia and A. esculentus fruit extracts could be formulated in a stable capsule dosage form with acceptable quality standards. Further biological studies such as toxicity assays and long-term efficacy studies of the developed capsules could be carried out before large-scale commercial production.

Optimization of oil-in-water emulsion capacity and stability of octenyl succinic anhydride-modified porang glucomannan (Amorphophallus muelleri Blume)

Surfactants are used to reduce surface and interfacial tension to form emulsions. Polysaccharides such as Porang Glucomannan (PG) with high viscosity can be used as surfactants. This research aimed to optimize the concentration of sodium carbonate (Na2CO3) and octenyl succinic anhydride (OSA) in modifying PG using a microwave. The optimization process is carried out using response surface methodology (RSM) with a two-factor central composite design (CCD), namely concentration of Na2CO3 (0.17–5.834%) and OSA (2.17–7.83%). The result showed that the concentration of Na2CO3 and OSA strongly influences emulsion capacity and stability. The optimum conditions that resulted in the highest emulsion capacity and stability were obtained at concentrations of Na2CO3 and OSA which were 2.25% and 6.19%, respectively. Degree of Substitution (DS), FTIR analysis, contact angle, and increased viscosity confirmed that OSA substitution occurred in PG. The characteristics of OSA-modified porang glucomannan (PGOS) such as: emulsion capacity and stability, Degree of Substitution (DS), contact angle, and viscosity increased to 34.6% and 32.5%, 1.02%, 92o, 5720 cP, respectively. FT-IR analysis confirmed the presence of OSA substitution at 1734 cm−1. PGOS can be used as a surfactant or gelator in oleogel production.

Study on optimization of coagulation-flocculation of fish market wastewater using bittern coagulant - response surface methodological approach.

Bittern contains a high ionic strength that can be used as an alternative coagulant in wastewater treatment. The magnesium content in the bittern could promote the removal of suspended particles and nutrients as settleable precipitates. This would create a more compact and manageable sludge. This study investigates the performance of bittern as a coagulant for fish market wastewater treatment. The effectiveness of bittern was evaluated based on the efficiency of pollutants removal and the amount of residual magnesium. The experiments were performed using a standard jar test. Response surface methodology (RSM) based on a two-factor central composite design (CCD) was used to design the experiment. The parameters involved were pH (7.5, 9, and 10.5) and coagulant dose (0.5, 1.5, 2.5 mL L-1). The maximum removal efficiencies (i.e., 93.3% TSS, 87.5% COD, 37.6% ammonium, and 91.3% phosphate) were recorded at pH 10.5 and 1.5 mL L-1 dose of bittern, while the optimum results (desirability value of 0.929) may occur at pH 10.5 and a dose of 1.284 mL L-1. Approximately 51% of struvite and 48% of calcite precipitates were identified in the generated sludge, which can possibly be used as supplementary material in agrochemical industry with further treatment.

Continuous Production of DHA and EPA Ethyl Esters via Lipase-Catalyzed Transesterification in an Ultrasonic Packed-Bed Bioreactor

Ethyl esters of omega-3 fatty acids are active pharmaceutical ingredients used for the reduction in triglycerides in the treatment of hyperlipidemia. Herein, an ultrasonic packed-bed bioreactor was developed for continuous production of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) ethyl esters from DHA+EPA concentrate and ethyl acetate (EA) using an immobilized lipase, Novozym® 435, as a biocatalyst. A three-level–two-factor central composite design combined with a response surface methodology (RSM) was employed to evaluate the packed-bed bioreactor with or without ultrasonication on the conversion of DHA + EPA ethyl ester. The highest conversion of 99% was achieved with ultrasonication at the condition of 1 mL min−1 flow rate and 100 mM DHA + EPA concentration. Our results also showed that the ultrasonic packed-bed bioreactor has a higher external mass transfer coefficient and a lower external substrate concentration on the surface of the immobilized enzyme. The effect of ultrasound was also demonstrated by a kinetic model in the batch reaction that the specificity constant (V′max/K2) in the ultrasonic bath was 8.9 times higher than that of the shaking bath, indicating the ultrasonication increased the affinity between enzymes and substrates and, therefore, increasing reaction rate. An experiment performed under the highest conversion conditions showed that the enzyme in the bioreactor remained stable at least for 5 days and maintained a 98% conversion.

Evaluating micellar liquid chromatographic methods on octadecyl particle-based and monolithic columns to predict the skin permeation of drug and cosmetic molecules

A micellar liquid chromatographic method was developed to assist in the modeling of the skin permeability of pharmaceutical and cosmetic compounds. The composition of the mobile phase was determined by means of a two-factor central composite design, after which it was tested on both a particle-based and monolithic column. The latter provided the opportunity to increase the flow rate from 1 to 8 mL/min without reaching too high backpressures. The micellar conditions allowed analyzing a large test set of compounds with diverse characteristics with just one mobile-phase composition. The obtained experimental chromatographic descriptors besides two sets of theoretical molecular descriptors were used to model the skin permeability coefficient log Kp, applying multiple linear regression and partial least squares regression approaches. The micellar method on the monolithic column provided useful models with similar or even slightly better performance parameters than the method on the particle-based column. Furthermore, a much faster analysis can be achieved when applying a flow rate of 8 mL/min, making the micellar monolithic method ideal to estimate skin permeability.

Production of new lipase from Preussia africana and partial characterization

The present work aims to study the production of a new extracellular lipase from the endophytic fungus Preussia africana isolated from red lapacho tree (Handroanthus impetiginosus). Tests were carried out in order to evaluate the influence of different inducing oils (sunflower, cotton, corn, palm kernel, canola and linseed) and carbon/nitrogen ratio (C/N of 11.73, 8.63 and 7.05) on submerged fermentation aiming at optimal production of a single extracellular lipase. Results show that an optimal lipase production of 14.5 kDa has been attained after 48 h of fermentation when sunflower oil was used in the C/N ratio of 8.63 in the fermentation medium. The produced lipase showed greater activity for oils that had higher percentage of unsaturated fatty acids in their composition. Characterization was performed using a two-factor central composite rotatable design (CCRD), and the pH 6 was found to be optimal (around 28 U/mL). The temperature range studied (from 20 to 54 °C) showed no difference for the lipase catalytic activity. This is an advantage, especially when aiming at its application in reactions of industrial interest.

Infrared heating under optimized conditions enhanced the pasting and swelling behaviour of cowpea starch

Native starches are not suitable for industrial use and must be modified for improved functionality. In this study, the effect of moisture preconditioning and infrared heating time on physicochemical properties of cowpea starch was investigated using a two-factor central composite rotatable design. Factors (moisture levels:10–40 g/100 g starch and infrared heating time:10–60 min) with their corresponding α mid-point values resulted in 13 experimental runs. Selected functional and pasting properties were determined as response variables. Starch samples produced under optimized conditions were compared with corn starch and their physicochemical properties determined. Except for pasting temperature, cowpea starch prepared using the optimal conditions (moisture: 46.21 g/100 g starch, dry basis and heating time of 32.88 min) had higher functional and pasting properties compared with the native cowpea starch. Infrared heating significantly reduced the gelatinization temperatures of cowpea starch but did not significantly change that of the corn starch. The crystallinity and double-helical order structure of moisture conditioned cowpea starch also reduced after modification. Cowpea starch showed a bigger granule size, higher swelling power but lower water absorption capacities and pasting properties compared with the control. The infrared heating process is a novel and promising modification method for improving the swelling properties of starch.

Effect of UV-C Irradiation and Lactic Acid Application on the Inactivation of Listeria monocytogenes and Lactic Acid Bacteria in Vacuum-Packaged Beef.

The objective of this study was to test the effect of the combined application of lactic acid (0–5%) (LA) and UV-C light (0–330 mJ/cm2) to reduce Listeria monocytogenes and lactic acid bacteria (LAB) on beef without major meat color (L *, a *, b *) change and its impact over time. A two-factor central composite design with five central points and response surface methodology (RSM) were used to optimize LA concentration and UV-C dose using 21 meat pieces (10 g) inoculated with L. monocytogenes (LM100A1). The optimal conditions were analyzed over 8 weeks. A quadratic model was obtained that predicted the L. monocytogenes log reduction in vacuum-packed beef treated with LA and UV-C. The maximum log reduction for L. monocytogenes (1.55 ± 0.41 log CFU/g) and LAB (1.55 ± 1.15 log CFU/g) with minimal impact on meat color was achieved with 2.6% LA and 330 mJ/cm2 UV-C. These conditions impaired L. monocytogenes growth and delayed LAB growth by 2 weeks in vacuum-packed meat samples throughout 8 weeks at 4 °C. This strategy might contribute to improving the safety and shelf life of vacuum-packed beef with a low impact on meat color.

Complying with the Guideline for Quality and Equivalence for Topical Semisolid Products: The Case of Clotrimazole Cream.

Semisolids constitute a significant proportion of topical pharmaceutical dosage forms available on the market, with creams being considered profitable systems for releasing active substances into the skin. This work aimed at the development of a generic Clotrimazole topical cream, based on the assumptions that assist the development of such formulations. First, the critical parameters to obtain a final formulation as similar as possible to the reference product were defined. Then, the percentages of cetyl palmitate and octyldodecanol were identified as critical variables and chosen for optimization in further studies. A “quality by design” approach was then used to identify the effect of process variability on the structural and functional similarity (Q3) of the generic product qualitatively (Q1) and quantitatively (Q2). A two-factor central composite orthogonal design was applied and eleven different formulations were developed and subjected to physicochemical characterization and product performance studies. The results were used to estimate the influence of the two variables in the variation of the responses, and to determine the optimum point of the tested factors, using a design space approach. Finally, an optimized formulation was obtained and analysed in parallel with the reference. The obtained results agreed with the prediction of the chemometric analysis, validating the reliability of the developed multivariate models. The in vitro release and permeation results were similar for the reference and the generic formulations, supporting the importance of interplaying microstructure properties with product performance and stability. Lastly, based on quality targets and response constraints, optimal working conditions were successfully achieved.

Microwave-Assisted Extraction of Andrographolide, 14-Deoxy-11,12- didehydroandrographolide and Neoandrographolide from Andrographis paniculata: An Optimisation Study

Background: Andrographis paniculata is often used as functional foods owing to its broad range of pharmaceutical activities due to the presence of main terpene compounds such as andrographolide, 14-deoxy-11,12-didehydroandrographolide and neoandrographolide. The aforementioned compounds must be extracted from the plant material before it can be routinely used as a functional food ingredient. Objective: This work presents an optimisation study of microwave-assisted extraction (MAE) of terpene from Andrographis paniculata. In this study, two factors at three-level central composite face centred design was employed to optimise the process variables, including the effect of microwave power (75-175 W) and ethanol concentration (20-85%) on extraction of terpene from Andrographis paniculata. Methods: The experimental design was set based on initial screening on the effect of mesh size and solid solvent ratio. The present work was performed at fixed mesh size and solid solvent ratio, which corresponds to the highest yield established experimentally. Two most significant factors, i.e. microwave power and ethanol concentration was chosen and further studied for optimisation using a response surface methodology. The three-level, two-factor central composite design (CCD) has been employed to determine the effect of microwave power (15, 25 and 35 W/mL) and ethanol concentration (20, 52.5 and 85%) on the yield of terpene extraction. Identification and quantification of the terpene were performed via Ultra-Performance Liquid Chromatography- Photodiode Array (UPLCPDA). Results: The regression analysis showed good fit of the experimental data to the quadratic equation with coefficient of determination (R2) value of 0.997. The optimum condition was found at microwave power of 140 W with 85% ethanol concentration, produced the highest yield of andrographolide (10.926 ± 0.053 mg/g DW), 14-deoxy-11,12-didehydroandrographolide (4.336 ± 0.215 mg/g DW) and neoandrographolide (5.698 ± 0.252 mg/g DW). The model developed through response surface modelling has a desirability of 97.5% and the error between the experiment and the model predictions ranged from 2.4 to 5.2%. Conclusion: A successful optimisation of terpene extraction from A. paniculata via MAE was achieved at microwave power of 140 W and 85% ethanol. The model developed from the regression analysis is sufficiently accurate and can be used to predict the yield of terpene extraction from A. paniculata.

Optimization of substrate composition in anaerobic co-digestion of agricultural waste using central composite design

Biochemical methane potential (BMP) tests and modelling of anaerobic co-digestion (AcoD) of ternary mixtures of agricultural waste, i.e., sugar beet root waste (BW), cow dung (CD), and poultry manure (PM), are presented. According to a two-factor central composite design (CCD), 12 BMP tests were conducted under mesophilic conditions for 30 days (d). CD mass fraction (0.146–0.854) in the animal manure mixture and C/N ratio (13.515–30.485) of ternary waste mixture were selected as process factors. Experimental values of ultimate cumulative methane yield as process response were in the range of 105.32–356.10 mL/g VS. A first-order rate model was applied to predict the process kinetics. Enhanced values of methane production rate, evaluated as rate constant (0.044–0.123 d−1), were obtained for lower levels of CD mass fraction and higher levels of C/N ratio. Response surface methodology (RSM) was applied to assess the effects of process factors on the response and to find the optimum factor levels leading to a maximum performance. A maximum value of response variable of 347.48 mL/g VS was predicted for a CD fraction of 0.323 and a C/N ratio of 26.24. Values of experimental ultimate methane yield of 358.45 ± 33.40 mL/g VS, obtained in the BMP tests at optimum levels of process factors, were close to that of the maximum response predicted by the statistical model, demonstrating the model validity. Moreover, a significant synergistic effect (an increase in methane yield by 41.2%) related to the weighed experimental BMP of substrate mixture was obtained under optimum conditions.

Roasting optimization and kinetics of raw and instant controlled pressure drop pre-treated coffee beans

Introduction: Coffee is one of the most widely consumed beverages in the world. The desired aroma and flavour of coffee are developed duringroasting which is the most important step in coffee processing. Instant Controlled Pressure Drop Process (DIC) technology is controlled hightemperature and short time process which been used successfully to improving the kinetics of drying, extraction, and decontamination of fresh and dried natural products. The main advantages of DIC are that it is a master controlled temperature and time process, the dwell times are short, reducing the chemical degradation, so new products with superior quality attributes may be developed. Materials and Methods: Two coffee beans varieties were investigated by Brazilian and Ethiopian sources. The raw beans were pre-treated using the DIC process under adopted conditions prior to roasting. A two-factor central composite design was used to optimize the settings of roasting time and roasting temperature on response variables of bulk, true and normalized density, and roasting degree. Also, microscopic analysis using Scanning Electron Microscopy (SEM) and kinetics of the roasting processes are included. Results and Discussion: The obtained results confirmed that the roasted DIC treated beans for both varieties have lower densities, higher roasting degree and lower activation energy needed for roasting compared to the raw beans. The physical properties’ magnitude is highly relevant to coffee origin. Roasting time and the temperature seemed to be of significant regarding all the physical characteristics of the beans, however, time was of topmost significance. Besides, treating coffee been by DIC prior to roasting leads to texture modification and conservation of time and energy needed for roasting. Conclusions: The physical properties of the roasted coffee beans are highly affected and changed with the coffee origin, roasting conditions and pre-treatment of coffee beans prior to roasting using the DIC process. The incorporation of the DIC process prior to roasting seemed to achieve more conservation of time and energy needed for roasting compared to the raw untreated beans. The higher degree of roasting and the competitive roasting activation energy of Brazilian coffee beans give aconclusion that more economic roasting process could be achieved with the Brazilian coffee. The pre-treatment by DIC enhances the remarkable reduction in coffee beans density and increasing in the roasting degrees that are in line with the industrial needs of coffee beverages. Response Surface Methodology is an efficient tool for optimization and mathematical modeling of the coffee roasting process.

Improving the Quality of Response Surface Analysis of an Experiment for Coffee-supplemented Milk Beverage: II. Heterogeneous Third-order Models and Multi-response Optimization.

This research was motivated by our encounter with the situation where an optimization was done based on statistically non-significant models having poor fits. Such a situation took place in a research to optimize manufacturing conditions for improving storage stability of coffee-supplemented milk beverage by using response surface methodology, where two responses are Y1=particle size and Y2=zeta-potential, two factors are F1=speed of primary homogenization (rpm) and F2=concentration of emulsifier (%), and the optimization objective is to simultaneously minimize Y1 and maximize Y2. For response surface analysis, practically, the second-order polynomial model is almost solely used. But, there exists the cases in which the second-order model fails to provide a good fit, to which remedies are seldom known to researchers. Thus, as an alternative to a failed second-order model, we present the heterogeneous third-order model, which can be used when the experimental plan is a two-factor central composite design having -1, 0, and 1 as the coded levels of factors. And, for multi-response optimization, we suggest a modified desirability function technique. Using these two methods, we have obtained statistical models with improved fits and multi-response optimization results with the predictions better than those in the previous research. Our predicted optimum combination of conditions is (F1, F2)=(5,000, 0.295), which is different from the previous combination. This research is expected to help improve the quality of response surface analysis in experimental sciences including food science of animal resources.

Ultrasound-Assisted Aqueous Extraction of Phenolic, Flavonoid Compounds and Antioxidant Activity of Mucuna macrocarpa Beans: Response Surface Methodology Optimization

Objective: This investigation was undertaken to optimize the effective extraction of total phenolics content (TPC), total flavonoids content (TFC), and antioxidant activity from the Mucuna macrocarpa (MM) beans. An ultrasound-assisted extraction (UAE) technique with water as an effective solvent was proposed for the response surface methodology (RSM) optimization.Methods: A three-level, two-factor central composite design (CCD) was employed to reveal the optimal points of variables. Different extraction times (5, 10, 15 minutes) and ultrasonic power levels (10, 20, 30 W) were used for the optimization. The experimental runs given by the RSM were evaluated for TPC, TFC, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (RSA), and N,N-dimethyl-p-phenylenediamine (DMPD) RSA and ferric reducing antioxidant power (FRAP).Results: The predicted times for maximum extraction of TPC (186.61 mg GAE g−1), TFC (148.87 mg QUE g−1), and DPPH RSA (99.37%), and DMPD RSA (50.58%) and FRAP (2.38 O.D. at 593 nm) were 12.57, 12.84, 12.43, 12.97, and 13.24 min, and ultrasonic power levels were found to be 27.30, 26.76, 26.22, 27.03, and 27.84 W, respectively. Reverse-phase high-performance liquid chromatography (RP-HPLC) analysis of phenolics compounds from the RSM optimized sample showed tannic acid (48.09 ± 1.92 mg/g), gallic acid (1.17 ± 0.19 mg/g), p-coumaric acid (0.56 ± 0.03 mg/g), and p-hydroxybenzoic acid (0.049 ± 0.01 mg/g) content.Conclusion: Water and ultrasonication were found to be an effective extraction solvent and technique. RSM was effectively employed to investigate the optimal process conditions for the maximum extraction of TPC, TFC, and antioxidant compounds from the MM beans. Further, MM beans can be explored as a prominent antioxidant source for the treatment of several disorders.

Polypropylene/chemically treated coir composites: optimizing coir delignification conditions using central composite design

The effect of alkaline treatment of coir on polypropylene/coir composite properties was investigated, using a two-factor central composite design where NaOH concentration and reaction time were varied. Alkaline treatment favored delignification, and at certain conditions, increased composite stiffness without loss in tensile strength. Increase in cellulose concentration likely increases the number of free hydroxyls, which is less favorable to composite mechanical properties. Treatments with 2 and 9% NaOH for 5 h resulted in cellulose concentration of about 50 and 70%, respectively. Treatments with high concentrations and for long periods are disadvantageous to composite properties, resulting in lower tensile strength likely due to the increased number of free hydroxyls as well as to possible breaks in cellulose structure. A desirability function, used to optimize the delignification process, revealed the highest tensile modulus and strength (3.5 GPa and 31 MPa, respectively) could be obtained at 5.75% NaOH and reaction time of 3 h.

Effects of electrode gap and electric current on chlorine generation of electrolyzed deep ocean water

Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmental friendly. A two-factor central composite design was adopted for studying the effects of electrode gap and electric current on chlorine generation efficiency of electrolyzed deep ocean water. Deep ocean water was electrolyzed in a glass electrolyzing cell equipped with platinum-plated titanium anode and cathode in a constant-current operation mode. Results showed that current density, chlorine concentration, and electrolyte temperature increased with electric current, while electric efficiency decreased with electric current and electrode gap. An electrode gap of less than 11.7 mm, and a low electric current appeared to be a more energy efficient design and operation condition for the electrolysis system.

Formulation and optimization of emulsions based on bitter fennel essential oil and EO/BO block copolymer surfactant

The influence of EO/BO block copolymer surfactant concentration in the range (1–5% (m/m)) and emulsification time on the emulsion stability and droplet size distribution of bitter fennel essential oil-in-water emulsions has been studied.Essential oils are promising material to be used for emulsion formulation with applications in cosmetics, food industry and agrochemicals. In the latter field these emulsions may be used as matrices for pesticides, where essential oils play the role of an eco-friendly solvent.A two-factor central composite design was conducted in order to optimize the emulsion formulation and processing. Emulsion stability has been studied as function of ageing time, by multiple light scattering (Turbiscan Lab-expert, Formulaction) and laser diffraction (Mastersizer X, Malvern). The surface response methodology allowed us to obtain a formulation comprising minimum droplet size and maximum stability by using a single step rotor/stator homogenization process.Creaming turned out to be the main destabilization mechanism. In order to improve emulsion stability the influence of high pressure homogenization (M110P, Microfluidics, MA, USA) and addition of a weighting agent (rosin gum) was studied. Although lower droplet sizes were obtained in both cases (D3,2 were in the range 0.30–0.35μm), emulsions were more unstable maybe due to Ostwald ripening phenomena.

Effects of electrolysis time and electric potential on chlorine generation of electrolyzed deep ocean water

Electrolyzed water is a sustainable disinfectant, which can comply with food safety regulations and is environmentally friendly. A two-factor central composite design was adopted for studying the effects of electrolysis time and electric potential on the chlorine generation efficiency of electrolyzed deep ocean water (DOW). DOW was electrolyzed in a glass electrolyzing cell equipped with platinum–plated titanium anode and cathode. The results showed that chlorine concentration reached maximal level in the batch process. Prolonged electrolysis reduced chlorine concentration in the electrolyte and was detrimental to electrolysis efficiency, especially under high electric potential conditions. Therefore, the optimal choice of electrolysis time depends on the electrolyzable chloride in DOW and cell potential adopted for electrolysis. The higher the electric potential, the faster the chlorine level reaches its maximum, but the lower the electric efficiency will be.