Central Composite Rotatable Experimental Design Research Articles

Modeling and Optimization of Microwave Osmotic Dehydration of Apple Cylinders Under Continuous-Flow Spray Mode Processing Conditions

The objective of this study was to model and optimize the mass transfer behavior during microwave osmotic dehydration of apple cylinders under continuous-flow spray mode processing conditions. Data needed for the model development and optimization were obtained using a central composite rotatable experimental design involving sucrose concentration (33.3–66.8°B), temperature (33.3–66.8 °C), flow rate (2,120–3,480 ml/min), and contact times (5–55 min); and the response variables were moisture loss, solids gain, and weight loss. Mass transfer kinetics was evaluated based on the empirical Azuara model and the conventional diffusion model. Diffusivities of both moisture loss (Dm) and solids gain (Ds) obtained from the diffusion model were related to sucrose concentration, temperature, and flow rate. Optimization was evaluated using a desirability function model which could be used with several imposed constraints. The optimum conditions obtained depended on the imposed constraints. A set of constraints involving maximizing moisture loss and weight reduction while keeping the solids gain below 3.5% gave the following optimal conditions: a 30-min osmotic treatment at 65°B, 60 °C, and 2,800 ml/min flow rate yielding a moisture loss of 40.9%, weight reduction of 37.7%, with a solids gain of 3.32%.

Influence of pumpkin seed oil in continuous phase on droplet size and stability of water-in-oil emulsions

The aim of this work was to contribute to the optimized production of water-in-oil emulsions with pumpkin seed oil in the oil phase using a high-speed homogenizer. Pumpkin seed oil is a valuable natural source of essential fatty acids and biologically active micronutrients that contribute to its nutritive value and medical uses, and reduce interfacial tension between water and the oil phases. Therefore, pumpkin seed oil can be considered as a prosperous oil phase whose use can possibly decrease the amount of some emulsifier that is normally involved in every emulsification process. A central composite rotatable experimental design was implemented to analyze the impact of the contents of polyglycerol polyricinoleate and pumpkin seed oil in the continuous phase, as well as water phase content in the emulsion on droplet size distribution and the response surface methodology was used to obtain optimal conditions for water-in-oil emulsion preparation. Mean size diameter of water droplets was in a range from 400 to 850 nm, with mean peak width of 100 to 220 nm, respectively. The influence of all three investigated factors on the emulsification was determined. Additionally, the emulsions prepared with pumpkin seed oil showed a higher stability during the storage time compared to the emulsions with sunflower oil.

Simultaneous abiotic reduction–biotic oxidation in a microbial-MnO 2-catalyzed Fenton-like system

The possibility of simultaneous activity of superoxide-mediated transformations and heterotrophic aerobic bacterial metabolism was investigated in catalyzed H 2O 2 propagations (CHP; i.e., modified Fenton's reagent) systems containing Escherichia coli. Two probe compounds were used: glucose for the detection of heterotrophic metabolism of E. coli, and tetrachloromethane (CCl 4) for the detection of superoxide generated in a MnO 2-catalyzed CHP system. In the MnO 2-catalyzed CHP system without bacteria, only CCl 4 loss was observed; in contrast, only glucose degradation occurred E. coli systems without CHP reagents. In combined microbial-MnO 2 CHP reactions, loss of both probes was observed. Glucose assimilation decreased and CCl 4 transformation increased as a function of H 2O 2 concentration. Central composite rotatable experimental designs were used to determine that the conditions providing maximum simultaneous abiotic–biotic reactions were a biomass level of 10 9 CFU/mL, 0.5 mM H 2O 2, and 0.5 g MnO 2. These results demonstrate that bacterial metabolism can occur in the presence of superoxide-mediated transformations. Such coexisting reactions may occur when H 2O 2 is injected into MnO 2-rich regions of the subsurface as a microbial oxygen source or for in situ oxidation; however, process control of such coexisting transformations may be difficult to achieve in the subsurface due to heterogeneity. Alternatively, hybrid abiotic reduction–biotic oxidation systems could be used for the treatment of industrial effluents or dilute solvent wastes that contain traces of highly halogenated compounds.

Coagulation Kinetics of High Pressure Treated Acidified Milk Gel for Preparation Chhana (An Indian Soft Cottage Cheese)

Chhana, an Indian cottage cheese, is one of the most popular heat-acid coagulated milk products. It forms the base material for a variety of milk-based sweets. Application of high pressure treatment for denaturation of milk protein has successfully been carried out. In the present study, high pressure in the range of 200–400 MPa for 0 to 100 min at coagulation temperature of 30–70°C was applied at constant acidity of milk-acid mixture in order to study the coagulated milk gel properties for preparation of chhana. The experiments were conducted using a central composite rotatable experimental design. Linear and non-linear regression equations, using the coded values of the independent variables were developed to study the effect of process variables on coagulated gel properties viz., lag time, mean coagulation rate and inflexion time. The optimum values of independent variables corresponding to minimum lag time, maximum coagulation rate and minimum inflexion time was obtained were high pressure - 280 MPa; pressurization time - 47 min; and coagulation time - 52°C. At this optimum condition of independent variables the lag time, mean coagulation time and inflexion time were 0.0028 min, 3.87 min, and 5.19 min, respectively.

OPTIMIZATION OF SYNBIOTIC FERMENTED FOOD FROM HYDROSOLUBLE SOY EXTRACT APPLYING EXPERIMENTAL DESIGN AND SENSORY ANALYSIS TECHNIQUES

ABSTRACT In this work, a synbiotic food from hydrosoluble soy extract was developed and tested. Food products made from soymilk have frequently been rejected because of their peculiar leguminous flavor. Although lactic fermentation promotes an improvement in final flavor, Bifidobacterium produces acetic acid, which renders off flavor in the product. To improve sensory features of soymilk's synbiotic beverage, 16 flavor compounds were evaluated by preliminary affective tests using hedonic scale. The ideal sweetness and flavor were optimized using experimental design and just‐about‐right scale. Sucrose concentration presented the highest significant effect (P ≤ 0.05). Products with higher sucrose contents (9.0–11.2 g/100 mL) and 0.08–0.16 g/100 mL of flavoring presented ideal sweetness. For ideal flavor, 11 g/100 mL sucrose content or higher with any amount of flavoring was considered ideal. In conclusion, predictive models for responses with respect to the ideal flavor and sweetness, overall acceptance and purchasing attitude of a soymilk symbiotic food were obtained and validated, with highly accepted and positive purchase intent (70%) by target public.PRACTICAL APPLICATIONSThe use of the just‐about‐right scale in sensory test is employed to measure the ideal amount of a determined compound that should be added to promote greater acceptance and preference according to the taste panel. Given that the sensory tests for the choice of the ideal are carried out in a linear manner and with one variable at a time, the present study has innovated in the application of the just‐about‐right scale, simultaneously evaluating two aspects of the ideal (sweetness and flavor) with a central composite rotatable design experimental design, and using the response surface methodology applied in the optimization of soymilk's symbiotic food. Predictive models for responses could be obtained to different sensorial optimizations in food researches.

Production of biofuels, limonene and pectin from citrus wastes

Production of ethanol, biogas, pectin and limonene from citrus wastes (CWs) by an integrated process was investigated. CWs were hydrolyzed by dilute-acid process in a pilot plant reactor equipped with an explosive drainage. Hydrolysis variables including temperature and residence time were optimized by applying a central composite rotatable experimental design (CCRD). The best sugar yield (0.41 g/g of the total dry CWs) was obtained by dilute-acid hydrolysis at 150 °C and 6 min residence time. At this condition, high solubilization of pectin present in the CWs was obtained, and 77.6% of total pectin content of CWs could be recovered by solvent recovery. Degree of esterification and ash content of produced pectin were 63.7% and 4.23%, respectively. In addition, the limonene of the CWs was effectively removed through flashing of the hydrolyzates into an expansion tank. The sugars present in the hydrolyzates were converted to ethanol using baker’s yeast, while an ethanol yield of 0.43 g/g of the fermentable sugars was obtained. Then, the stillage and the remaining solid materials of the hydrolyzed CWs were anaerobically digested to obtain biogas. In summary, one ton of CWs with 20% dry weight resulted in 39.64 l ethanol, 45 m 3 methane, 8.9 l limonene, and 38.8 kg pectin.

COMPARATIVE STUDY OF WIRELESS VERSUS STANDARD THERMOCOUPLES FOR DATA GATHERING AND ANALYSES IN ROTARY COOKERS

ABSTRACT The performance of a wireless temperature sensor was compared with that of a conventional thermocouple for gathering heat penetration data. A central composite rotatable design experimental design with three different processing conditions (glycerin concentration [70–100%], retort temperature [111.6–128.4C] and retort speed [4–24 rpm]) were employed using 307 × 409 cans containing the particulate fluid to compare the performance of the two devices. Experiments were performed in a fixed axial mode of rotation in a rotary cooker, and only liquid temperature was measured using both temperature sensors. The heating rate index, fh, cook value to lethality ratio, CO/FO, were evaluated and compared using a t-test. Statistically there were no differences (P > 0.05) in the performance of the two systems with respect to the parameters tested; however, compared with conventional thermocouples, the wireless sensors were more stable, and more practical for use in rotary cookers especially for free axially rotating cans. PRACTICAL APPLICATIONS In order to meet the recent industrial demand to optimize the thermal process in rotary cookers, it is imperative that time-temperature data during processing be accurately gathered. To gather temperature data in rotary retorts, standard thermocouples equipped with a slip ring assembly are used together with a data acquisition set up. A biaxially rotating can, as in continuous cooker simulators, would require two such slip rings: one at the can level and one at the retort level, making the data gathering more cumbersome. To assist in such scenarios, use of self-contained “wireless” sensors is more practical. This study focuses on concerns about using wireless sensors due to their own volume influencing the temperature measurement at the critical control point. This study will demonstrate that wireless sensors could potentially replace standard thermocouples for the measurement of temperature for convection-heated food in large size 307 × 409 cans.

Comparison of Artificial Neural Network (ANN) and Response Surface Methodology (RSM) in the Prediction of Quality Parameters of Spray-Dried Pomegranate Juice

Response surface methodology (RSM) is a frequently used method for empirical modeling and prediction in the processing of biological media. The artificial neural network (ANN) has recently grown to be one of the most efficient methods for empirical modeling and prediction, especially for nonlinear systems. This article presents comparative studies between an ANN and RSM in the modeling and prediction of quality parameters of spray-dried pomegranate juice. In this study, the effects of the carrier type, carrier concentration, and concentration of crystalline cellulose in a pomegranate juice spray-drying process were investigated on five quality parameters—drying yield, solubility, color change, total anthocyanin content, and antioxidant activity—using RSM and ANN methods. A central composite rotatable experimental design (CCRD) and a feed-forward multilayered perceptron (MLP) ANN trained using back-propagation algorithms for three independent variables were developed to predict the five outputs. The final selected ANN model (3-10-8-5) was compared to the RSM model for its modeling and predictive abilities. The predictive abilities of both the ANN and RSM were compared using a separate dataset of 18 unseen experiments based on RMSE (root mean square error), MAE (mean absolute error), and R2 (correlation coefficient) for each output parameter. The results indicate the superiority of a properly trained ANN in capturing the nonlinear behavior of the system and the simultaneous prediction of five outputs.

Synthesis of structured lipid with balanced omega-3: Omega-6 ratio by lipase-catalyzed acidolysis reaction: Optimization of reaction using response surface methodology

The present study deals with the production of structured lipid containing omega-3 and omega-6 fatty acids in the ratio of 1:1 by incorporating omega-3 fatty acids (α-linolenic acid) from linseed oil into groundnut oil using lipase (Lipozyme IM from Rhizomucor miehei) catalyzed acidolysis reaction in hexane. The reaction conditions were optimized by response surface methodology with a four-variable five-level central composite rotatable experimental design. The influence of four independent parameters, namely ratio of fatty acid concentrate from linseed to groundnut oil (0.66–1.98, w/w), reaction temperature (30–60 °C), enzyme concentration (1–5%) and reaction time (2–54 h) on omega-3 fatty acids incorporation into groundnut oil were optimized. Optimal conditions for the structured lipid containing omega-3 to omega-6 fatty acids in the ratio of 1:1 were determined to be; enzyme concentration 3.75% (w/w), temperature 37.5 °C, incubation time 30.81 h and ratio of free fatty acid concentrate from linseed oil to groundnut oil 1.16 (w/w).

Multiresponse optimization based on the desirability function for a pervaporation process for producing anhydrous ethanol

A pervaporation process for producing anhydrous ethanol from industrial ethyl alcohol (95% v/v) was performed with a commercial PVA/PAN membrane. A central composite rotatable experimental design together with response surface methodology was implemented for studying and modeling the influence of operating conditions in terms of the temperature and the flow rate of the feed on the pervaporation performance, namely, the permeate flux and the separation factor. To obtain a trade-off between the permeate flux and the separation factor, a method for si- multaneous optimization of multiple responses based on an overall desirability function was used. The optimization resulted in a feed temperature of 66 o C and a feed flow rate of 42 L/h. These operating conditions are expected to respond with a permeate flux of 0.107 kg/m 2 h and a separation factor of 40, which correspond to a satisfactory overall desirability.

The Effect of Additives on Vacuum Dried Honey Powder Properties

Vacuum drying of liquid honey was carried out using three additives, i.e., maltodextrin (drying agent), glycerol monostreate (flowability agent) and tricalcium phosphate (anti-caking agent). The drying experiments were conducted through a central composite rotatable (CCR) type experimental design with three levels and five variables to study the effect of the additives on the vacuum dried honey powder properties. The maximum and minimum level of malto dextrin, glycerol monostreate and tricalcium phosphate used in the experiments were 0.6-0.35 kg.kg dry honey solid-1, 0.02-0.01 kg.kg dry honey solid-1 and 0.02-0.01 kg.kg dry honey solid-1, respectively. The amount of maltodextrin, glycerol monostereate, and tricalcium phosphate required to reduce powder stickiness and caking and increase powder flowability were optimized based on the commercially available honey powder properties. At the optimum ranges of maltodextrin (0.429-0.55 kg.kg dry honey solid-1), glycerol monostereate (0.0121-0.0157 kg.kg dry honey solid-1), and tricalcium phosphate (0.0147-0.0156 kg.kg dry honey solid-1), the range of powder properties were: hygroscopicity= 8.33-10.27%; degree of caking=10.24-11.50%; flowability=22-24.56s; overall colour difference=5.8-7.9 and sticky point temperature = 45.5-50.65°C.

Oxidation by Fenton's reagent combined with biological treatment applied to a creosote-comtaminated soil

In this study, we investigated the feasibility of using Fenton oxidation to remove sorbed polycyclic aromatic hydrocarbons (PAHs) in aged soil samples with creosote oil from a wood preserving site. The optimal dosage of reagents was determined by a statistical method, the central composite rotatable experimental design. The maximum PAH removal was 80% with a molar ratio of oxidant/catalyst equal to 90:1. In general low molecular weight PAHs (3 rings) were degraded more efficiently than higher molecular weight PAHs (4 and 5 rings). The hydrogen peroxide decomposition kinetic was studied in the presence of KH 2PO 4 as stabilizer. The kinetic data were fitted to a simple model, the pseudo-first-order which describes the hydrogen peroxide decomposition. The PAH kinetic degradation was also studied, and demonstrated that non-stabilized hydrogen peroxide was consumed in less than 30 min, whilst PAH removal continued for up to 24 h. In a second part of the work, a combined chemical and biological treatment of the soil was carried out and shown to be dependent on the pre-oxidation step. Different reagent doses (H 2O 2:Fe) were used (10, 20, 40, 60:1) in the pre-treatment step. An excess of hydrogen peroxide resulted in a poor biological removal, thus the optimal molar ratio of H 2O 2:Fe for the combined process was 20:1. The combined treatment resulted in a maximum total PAH removal of 75% with a 30% increase in removal due to the biodegradation step. The sample with highest PAH removal in the pre-oxidation step led to no further increase in removal by biological treatment. This suggests that the more aggressive chemical pre-oxidation does not favour biological treatment. The physico-chemical properties of the pollutants were an important factor in the PAH removal as they influenced chemical, biological and combined treatments.

Biscoitos de polvilho azedo enriquecidos com fibras solúveis e insolúveis

This work evaluated the use of wheat bran and polidextrose as fiber sources to enrich fermented cassava starch biscuits. The Response Surface Methodology was used to verify the influence of the addition of these fiber sources on the quality parameters of the biscuits. The responses of the 22 central composite rotational experimental design that were evaluated were specific volume, hardness, and moisture and color - parameters L, a*, and b*. For the specific volume and hardness responses, all factors were significant: 95% confidence level, with R² of 0.9307 and 0.8091, respectively. Analyzing the surfaces obtained it could be observed that the wheat bran and polidextrose reduced the specific volume and the wheat bran had a greater effect in increasing hardness. The substitution of fermented cassava starch by wheat bran and polidextrose in proportions of 1.5 and 5%, respectively, produced a fiber-rich sample with 6.23% dietary fiber (calculated theoretically) without affecting the expansion and texture characteristics negatively and with a good sensory acceptance.

Optimization study of citrus wastes saccharification by dilute-acid hydrolysis

The effects of time, acid concentration, temperature and solid concentra-tion on dilute-acid hydrolysis of orange peels were investigated. A central composite rotatable experimental design (CCRD) was applied to study the individual effects of these hydrolysis factors and also their inter-dependence effects. The enzymatic hydrolysis of the peels by cellulase, β-glucosidase, and pectinase enzymes resulted in 72% dissolution of the peels, including 18.7% galacturonic acid and 53.3% of a total of glucose, fructose, galactose, and arabinose. Dilute-acid hydrolysis up to 210°C was not able to hydrolyze pectin to galacturonic acid. However, the sugar polymers were hydrolyzed at relatively low temperature. The optimum results were obtained at 116°C, 0.5% sulfuric acid concentration, 6% solid fraction, and 12.9 min retention time. Under these conditions, the total sugars obtained at 41.8% dry peels and 2.6% of total hexose sugars were further degraded to hydroxymethylfurfural (HMF). No furfural was detected through these experiments from decomposition of pentoses.

Optimization of process variables for the preparation of expanded finger millet using response surface methodology

The decorticated finger millet was subjected to high temperature short time treatment to prepare expanded millet, a ready-to-eat new generation product. It was observed that, flattening the grains to the desired shape factor and the moisture content were critical factors for obtaining the millet with maximum expansion ratio. Accordingly, the effect of moisture content of the millet prior to flattening, the shape factor and drying time and their complex interaction on the expansion ratio of the millet were determined. Besides, the bulk density, sphericity, hardness and overall acceptability of the expanded millet were also evaluated using a central composite rotatable experimental design. Based on the design, the optimal conditions for obtaining fully expanded millet were, moisture content of about 40% prior to flattening, shape factor ranging from 0.52 to 0.58 and drying time varying from 136 to 150 min. The product prepared under these conditions had an expansion ratio ( Y 1) ⩾ 4.6, bulk density ( Y 2) ⩽ 0.17 g/cm 3, sphericity ( Y 3) ⩾ 0.90, hardness/texture ( Y 4) ⩽ 5.0 N and the overall acceptability ( Y 5) ⩾ 7.2.

Optimization of starch oleate derivatives from native corn and hydrolyzed corn starch by response surface methodology

Conditions for the preparation of starch oleates of native and hydrolyzed corn starch were compared with the aim of developing a hydrophobic starch as gum arabic substitute for use as a wall material in microencapsulation. Optimization of the reaction parameters for maximization of degree of substitution (DS) of starch oleate was carried out using response surface methodology (RSM). Corn starch and maltodextrins of dextrose equivalent (DE) 12 and 18 were used in the study. A central composite rotatable experimental design (CCRD) was chosen to explain the combined effects of the three parameters, viz., oleic acid concentration, reaction time and reaction temperature to design minimum number of experiments. The optimal levels of the three parameters for corn starch (50 g) were an oleic acid concentration of 1.2 g, a reaction time of 201 min at 160 °C, wherein a maximum DS of 0.021 was obtained. For maltodextrin of 12 DE, 1.53 g oleic acid concentration, a reaction time of 334 min at 150 °C gave a corresponding DS of 0.0353. Similarly, for 18 DE, 1.36 g oleic acid concentration, a reaction time of 300 min at 129 °C gave a DS of 0.053. The optimized samples were compared to gum arabic with respect to emulsifying capacity.

Bread from composite cassava-wheat flour: I. Effect of baking time and temperature on some physical properties of bread loaf

Abstract The use of composite cassava-wheat (CCW) flour for commercial breadmaking purposes and consumption of CCW bread are relatively new in Nigeria. This study investigated the effect of baking temperature and time on some physical properties of bread from composite flour made by mixing cassava and wheat flour at ratio of 10:90 (w/w). A central composite rotatable experimental design was used while the baking temperature and time investigated ranged from 190 to 240 °C and 20 to 40 min, respectively. Loaf volume, weight and specific volume varied significantly ( p 3 , 162 to 183 g and 3.31 to 5.32 cm 3 /g, respectively. The tristimulus color parameters such as L ∗ (lightness) and brownness index (BI) of the crust varied significantly ( p p 3 , 0.69 to 0.80, 13.00 to 18.05 mm and 0.90 to 2.05 kgf, respectively. Due to the complex effect of temperature and time combination, most of the measured properties could not be reliably predicted from the second order response surface regression equations except the loaf weight and crumb moisture. Further studies are required to optimize the CCW bread baking process based on some storage and consumption qualities.

OPTIMIZATION OF ENZYMIC EXTRACTION OF EDIBLE GELATIN FROM CATTLE BONES USING RESPONSE SURFACE METHODOLOGY (RSM)

Gelatin is a protein hydrocolloid. Because of its unique characteristics such as gel forming, thickening, stabilizing, emulsifiing, foam and film forming, is widely used in food industries. In this research, in order to optimize the factors which affect enzymatic extraction method of gelatin ,the effects of three variables, enzyme concentrations(2-10 ppm), time(8-16 hours) and temperature(60-80 ˚C) on the yield of extraction, gel strength, viscosity and absorption in 420 nm were investigated. The rotatable central composite experimental design was used, and the data were analyzed by using of response surface regression(RSREG).Correlation coefficients of fitted regression models of yield, gel strength, viscosity and absorption for enzyme extraction method were determined as 0.953 , 0.998 , 0.995 and 0.935 , respectively.Analysis of variance for the overall effects of process variables in enzymatic extraction method on regression models showed that the enzyme concentration, the time of enzyme treatments and temperature had significant effects on gel strength and viscosity regression models, however the effect of temperature on both yield and absorption regression models was not significant(p > 0.05).The optimum conditions obtained from response surface regression models in enzymatic extraction method for yield, gel strength, viscosity and absorption which were verified experimentalls were (6.1 ppm, 15.6 hours, 70 ˚C), (9.1 ppm, 11.9 hours, 70.3 ˚C), (7.86 ppm, 14.9 hours, 77.5 ˚C) and (2.8 ppm, 10 hours, 60 ˚C), respectively. Key words: gelatin, enzymatic extraction, response surface optimization

Response surface analysis of electro jet drilled holes

Modern trend towards miniaturization has given a new impetus to the development of nontraditional small hole drilling techniques. Electro jet drilling (EJD) is one such promising technique which is finding ever increasing applications in several industries including aerospace, space, medical, automobile and microfabrication (electronic and computers). The present study investigates the relationships and parametric interactions between three controllable variables on the material removal, radial overcut and hole taper in the EJD process. Experiments have been conducted on SUPERNI 263A workpieces. Applied voltage, electrolyte concentration and feed rate were selected as independent process variables. The responses have been modelled using a response surface model based on a central composite rotatable experimental design. The significant coefficients were obtained by performing analysis of variance (ANOVA) at 1% and 5% level of significance. It was found that applied voltage, electrolyte concentration and feed rate have significant effect on the material removal, radial overcut and hole taper.

Simultaneous Optimization of a Multi‐response System by Desirability Function Analysis of Boondi‐making: A Case Study

ABSTRACTResponse surface methodology (RSM) was used to investigate the influence of 3 important independent processing variables–batter concentration (36% to 44%), frying temperature (160 °C to 200 °C), frying time (180 to 300 s)–on the various quality characteristics of the fried chickpea batter balls called boondi. Instrumental color parameters L, a b, and tan‐1(b/a), oil content, and sensory attributes like color, oily appearance, uniformity of boondi, crumbliness, and overall quality (OQ) were measured and used as response variables. The effects of the processing variables of frying were studied by adopting a standard Central Composite Rotatable (CCR) experimental design. The response variables were fitted to predictive quadratic polynomial models using multiple regression. Applying the desirability function analysis (DFA), optimal‐quality boondi was obtained with a maximum overall quality score of 12.7 on a 15‐cm quantitative descriptive analysis (QDA) scale, when the batter concentration, frying temperature, and frying time were 40.4%, 182 °C, and 240 s, respectively.