Response Surface Experimental Design Research Articles

Formulation of Saxagliptin Oral Films: Optimization, Physicochemical Characterization, In-Vivo Assessment, and In-Vitro Real-Time Release Monitoring via a Novel Polyaniline Nanoparticles-Based Solid-Contact Screen Printed Ion-Selective Electrode

Oral dispersible films have received broad interest due to fast drug absorption and no first-path metabolism, leading to high bioavailability and better patient compliance. Saxagliptin (SXG) is an antidiabetic drug that undergoes first-path metabolism, resulting in a less active metabolite, so the development of SXG oral dispersible films (SXG-ODFs) improves SXG bioavailability. The formula optimisation included a response surface experimental design and the impact of three formulation factors, the type and concentration of polymer and plasticiser concentration on in-vitro disintegration time and folding endurance. Two optimised SXG-ODFs prepared using either polyvinyl alcohol (PVA) or hydroxypropyl methylcellulose were investigated. SXG-ODFs prepared with PVA demonstrated a superior rapid disintegration time, ranging from 17 to 890 s, with the fastest disintegration time recorded at 17 s. These short durations can be attributed to the hydrophilic nature of PVA, facilitating rapid hydration and disintegration upon contact with saliva. Additionally, PVA-based films displayed remarkable folding endurance, surpassing 200 folds without rupture, indicating flexibility and stability. The high tensile strength of PVA-based films further underscores their robust mechanical properties, with tensile strength values reaching up to 4.53 MPa. SXG exhibits a UV absorption wavelength of around 212 nm, posing challenges for traditional quantitative spectrophotometric analysis, so a polyaniline nanoparticles-based solid-contact screen-printed ion-selective electrode (SP-ISE) was employed for the determination of SXG release profile effectively in comparison to HPLC. SP-ISE showed a better real-time release profile of SXG-ODFs, and the optimised formula showed lower blood glucose levels than commercial tablets.Graphical

Production of Mannooligosaccharides from Açaí Seed by Immobilized β-Mannanase

In this work, an enzyme cocktail with β-mannanase as the main activity was immobilized on epoxy resin foams filled with fibers from annatto capsules. The catalytic system was characterized by SEM, FTIR, and a mechanical crush resistance test. The behavior of the pH and temperature for the hydrolysis of the locust bean gum were also studied. With the same substrate and with respect to the free enzyme, the immobilized enzyme showed an activity retention of 79.61%. Its operational stability in ten reuse cycles did not show any statistically significant loss of activity. This catalytic system was used to study the preferential release of MOS of two to five degrees of polymerization from mannan present in dried and ground açaí seeds, which were not subjected to any other pretreatment. Using an experimental response surface design, the predicted quadratic models for the M2–M5 MOS content were obtained and they fit well with the experimental data, predicting a production range between 0.435 and 20 g/L of MOS (M2–M5). In addition, the production reached about 12 g/L under the optimized conditions. These results indicate that the used foamed epoxy resin supports and immobilization methodology are suitable for catalyzing the hydrolysis of mannan from açaí seeds.

Response surface experimental design for simultaneous chromatographic determination of two antiviral agents “Favipiravir and Remdesivir” in pharmaceuticals and spiked plasma samples

Response surface experimental design for simultaneous chromatographic determination of two antiviral agents “Favipiravir and Remdesivir” in pharmaceuticals and spiked plasma samples

Development and Optimization of Cassava (Manihot Esculenta) Peeling Machine

The conventional cassava peeling methods are inefficient, time-consuming, and labor-intensive This study aimed to create an enhanced cassava peeling machine with minimal flesh loss. The machine design includes components like a hopper, shafts, bearings, an electric motor, and a v belt connected to a pulley that drives the brush-equipped shaft. This locally sourced and fabricated machine, designed for 50kg of cassava tubers, was tested at operational speeds of 380, 420, and 460 rpm and retention times of 4, 6, and 8 minutes, optimizing the effects of machine speeds and peeling times on peeling efficiency using I-optimal Response Surface Experimental Design with a mean separation at P<0.05. Results pertaining to tuber properties, such as angle of repose, peel thickness, moisture content, peel penetration force, bulk density, and coefficient of friction, were utilized in the machine's design. The machine achieved maximum peeling efficiency of 74% at a speed of 380m/s when operated for 6 minutes. At this optimal efficiency, the machine reached an optimal throughput capacity of 171.4kg/h, with a 21% flesh loss, a peeling weight proportion of 25.8%, and minimal tuber damage (3.3%). The desirability, which signifies the extent to which these optimal values align with the optimization goal, was 0.83 (83%). In essence, this machine significantly advances cassava peeling mechanization.

Optimization of inclined coal seam tunnel section angle and anchor angle based on response surface method

The mining of inclined coal seams is often accompanied by problems such as difficult to control deformation of the tunnel roof and failure of anchor bolts. Taking the transportation channel of Jinping Coal Industry 1071-1 in Shanxi Xiangkuang Mine as the background, FLAC3D numerical simulation software was used, and the method of response surface experimental design and data analysis was used to systematically study the effects of the anchor installation angle and the roof inclination angle of the tunnel section on different inclination angles. Influence of the surrounding rock stability of coal seam roadways. On this basis, a multi-index tunnel support design evaluation method based on the response surface method was proposed, and the actual support plan was optimized and industrial tests were carried out based on the actual on-site support plan. The research results show that: in terms of inclined coal seam support, the degree of influence on the tunnel stability is in the following order: anchor installation angle > tunnel section roof inclination angle > coal seam inclination angle; the optimized support design obtained through the proposed technology The method has good application effect and can improve the stability of the roadway during the mining of the working face. It also proves the effectiveness of this technology and provides new ideas for the design of anchor support of inclined coal seam roadways and the optimization of roadway sections.

Evaluating the prediction power and accuracy of two smart response surface experimental designs after revisiting repaglinide floating tablets

BackgroundThere is a soar in the figure of companies aiming to achieve efficiency in undergoing experimental processes. Therefore, instead of deploying one-factor-at-a-time, design of experiments is becoming rampantly utilized in order to reduce the resources outflow. There are a copious of different smart designs which could be employed as design of experiments tools. Central composite and d-optimal designs were investigated in this paper. The purpose of this investigation was to compare the two designs and identify the most accurate design at analyzing, interpreting and making predictions with regards to the data offered. The aforementioned purpose was achieved by applying both designs to a preexisting study which sought to prolong the gastrointestinal retention of repaglinide tablets through deploying a full factorial design. Further optimization was performed using Design-Expert software after inducing an outlier point.ResultsR-squared, adjusted R-squared, predicted R-squared and adequate precision were computed in addition to acquiring diagnostics figures such as predicted versus actual, residual versus run, Box–Cox, contour plot and 3D surface plots. Model equations were also produced for each design. Results showed that both designs were successful at modeling the data both scoring r-squared values > 0.7 and adequate precision > 4 implying high fitting, prediction power and ability to navigate the experimental space using a reduced number of experimental runs. The d-optimal design obtained the least relative error of only 3.81%.ConclusionsIn conclusion, the d-optimal design provides a great tool for reduction of experimental testing which in turn diminishes resources consumption. Therefore, this design is favored to be enforced in the pharmaceutical sector.

Experimental and statistical investigation on flexural properties of FDM fabricated PLA specimens applying response surface methodology

Additive manufacturing (AM) is a modern technology currently adopted by manufacturing industries to benefit from its low-cost applications, versatility and fabrication of complex parts. Fused deposition modeling (FDM) is distinguished among the different AM technologies due to its fast, yet accurate operations. However the properties of fabricated components are strongly depended by FDM-related parameter settings. This work examines the effect of FDM-related parameters namely flow rate, printing speed and printing temperature on the response of flexural strength. Experiments according to L9 orthogonal array and a custom response surface experimental design were performed to obtain the results necessary for further examination and analysis corresponding to parameter effects on flexural strength and statistical outputs. Experiments were designed as per the ASTM D790 standard whilst failure modes of experimental samples were observed for correlating the independent printing parameters with the response of flexural strength. The full quadratic regression model generated for predicting results concerning flexural strength was found adequate for explaining the variation of FDM-related parameters on flexural strength response.

An efficient hybrid methodology for optimization of CO2 Huff-n-Puff EOR and sequestration in tight oil reservoirs

CO2 Huff-n-Puff is one of the effective enhanced oil recovery (EOR) methods in tight oil reservoirs, which is also attractive to sequestrating CO2 underground. Therefore, CO2 Huff-n-Puff EOR and sequestration project is particularly important both for oil and gas industry and environmental protection field. However, the technique has not gained industry-wide adoption partly due to knowledge gaps in efficient optimization of CO2 Huff-n-Puff EOR and sequestration using compositional numerical simulation. The purpose of this work is to propose an efficient hybrid optimization methodology which is called proxy-model-based optimization with initialization constraint. Two cases for single objective optimization and multi-objective co-optimization of CO2 Huff-n-Puff EOR and sequestration with two objective functions were investigated. Our findings suggest that the optimization performance of proxy-model-based optimization is highly dependent on the relative errors of the proxy model compared with simulator-based optimization. The optimization performance of proxy-model-based optimization with initialization constraint is 4∼10 % lower than that of simulator-based optimization, but the reduction in the number of simulations and improving the robustness of a stochastic optimizer are very attractive. In addition, different objective functions and optimization mode have different sensitive parameters. To the best of our knowledge, this is the first time to conduct single/multi-objective optimization of CO2 Huff-n-Puff EOR and sequestration in tight oil reservoirs based on numerical simulation technology, method of response surface experimental design and single/multi-objective particle swarm optimization algorithm. We believe the proposed methodology in this work is efficient especially for large reservoir simulations and rapid prediction of optimization schemes.

Study on the preparation and use of edible coating of fish scale chitosan and glycerol blended banana pseudostem starch for the preservation of apples, mangoes, and strawberries

Agro-industries and the fish processing sector generate large amounts of waste, which may be converted into useful ingredients for preserving fruit. Studies show that starch-based edible film still needs some improvement because it’s brittle and weaker, which might be improved by adding chitosan. The study aimed to investigate the optimal composition of edible film-forming material prepared from banana pseudostem starch and fish-scale chitosan to preserve the selected fruits. In the current study, chitosan and starch were extracted from the waste of Nile tilapia fish scale and Dwarf cavendish banana pseudostem as found to be 29.66 ± 0.46 % and 4.26 ± 0.21 %, respectively. Central composite response surface experimental design combined banana pseudostem starch, chitosan, and glycerol to prepare the edible films. Using the Design-expert program, the ideal film-forming composition with an overall acceptability of 0.968 was identified based on the physico-mechanical characteristics of the created composite edible films. It comprised 15 mL of 1 % banana pseudostem starch, 3.2 mL of 0.5 % chitosan, and 0.6 mL of 30 % glycerol. The persistence of the microbial load on coated and uncoated fruits throughout the storage was also assessed in the study. The microbial and fungal growth was significantly lower (>37 %) in optimal edible film-coated fruits than in the control fruits. After 28 days of storage of fruits at room temperature, the microbial count (in CFU/mL) on the edible coated surfaces of apples, mangoes, and strawberries was found to be 2.04 ± 0.32x103, 2.71 ± 0.29x103, and 2.5 ± 0.51x104, respectively. Also noticed the fungus counts of 1.86 ± 0.48x03 (in apples), 1.09 ± 0.11x104 (in mangoes), and 1.56 ± 0.04x104 (in strawberries) in the studied coated fruits after 28 days of storage. Furthermore, the film-coated fruits had a significantly lower weight loss than uncoated fruits. Thus, the studied banana pseudostem starch-chitosan-glycerol composite edible coating potentially preserves by inhibiting the development of natural microbes when storing apples, mangoes, and strawberries, and it is adequate to extend their shelf life.

Predicting minty compounds binary mixtures' pleasantness by odor intensity in aqueous solutions.

The aroma of mint is well-liked by the public, and key flavor odorants in mint aroma had been found, but how these molecules interact and form a satisfying odor remains a challenge. Quality, intensity, and pleasantness are our most basic perceptions of aromas; both intensity and pleasantness can be quantified. However, compared to intensity, research on pleasantness was lacking. Pleasantness was one of the most important indicators for formulating a satisfying mint flavor, and the study of binary mixtures was fundamental to our understanding of more complex mixtures. Therefore, the purpose of this study was to explore the characteristics of pleasantness as a function of concentration and, at the same time, to investigate the relationship between intensity and pleasantness in binary mixtures. Thirty sensory evaluation volunteers participated in the evaluation of the intensity and pleasantness of six key flavor odorants of mint and five binary mixtures. The results showed that the pleasantness increased first and then decreased or stabilized with the rising of concentration; even though the interactions in binary mixtures were not the same, their pleasantness could be predicted using the intensities of the components by Response Surface Design of Experiments, and the goodness of fit was greater than 0.92, indicating that the models had the great predictive ability. PRACTICAL APPLICATION: Whether blending flavors or evaluating them, a great deal of experience is required, yet the acquisition of this experience is a long process. Performing these tasks is difficult for the novice, and it helps to quantify the feeling for the flavor and build some mathematical models.

Tailoring the formulation of sugar-snap cookies to lower in vitro starch digestibility: A response surface modelling approach

An I-optimal response surface experimental design revealed impacts of dough moisture content (DMC, 14–22%) and level of wheat flour substitution (10–50%) by wheat gluten and one of six different native starches [wheat, (waxy) maize, rice, potato, pea] on sugar-snap cookie starch thermal properties, in vitro starch digestion, dough and cookie hardness and spread ratio. Increasing DMCs from 14 to 22% increased the cookie starch digestion rate constants of each starch source used. A linear increase of the constant by 25–30% across the 14 to 22% DMC range for all starches was predicted and validated. That cookie spread and hardness were related to the water retention capacity of the native starches used suggested that they underwent limited changes during baking. For each starch examined, formulations were optimized to lower in vitro starch digestion rate and extent, and cookie hardness, while maximizing dough spread ratio.

Agrofood Waste and By-Product Valorization, Extraction, and Characterization of Pectin from the Waste Biomass Fruit Peel of Aframomum angustifolium Using Response Surface Methodology as Alternative Sources of a Functional Pectin

Applications of pectin in the food industry are strongly influenced by their source, structures, and extraction methods, which affect their functionalities. This research aims to extract and assess pectin’s physicochemical and functional properties from waste biomass peels of Aframomum angustifolium as an alternate source using acid (AAE) and microwave extraction (MAE) methods. Pectin extracted from A. angustifolium was compared based on yield, color, moisture, equivalent weight, methoxyl content (MC), and degree of esterification (DegE). Response surface experimental design was used to study the effect of the extraction process pectin such as the yield and the DegE. MAE had a significantly higher % yield of 4.74 ± 0.1% and a lower equivalent weight of 852.49 ± 16.59 mg/ml than AAE with 3.09 ± 0.03% and 882.1 ± 9.04 mg/ml, respectively, with light brown color. The lower moisture contents of 6.5%, MC of 33.06%, and DegE of 67.96% were obtained by MAE compared to 6.9%, 31.85%, and 66.61%, respectively, for AAE. The time and temperature had a positive significant effect ( p < 0.05) on % pectin yield for MAE and AAE, while time and pH squared had a negative. Temperature squared had a negative significance on % DE, and pH had a positive significance using AAE and MAE. Optimal conditions for MAE obtained were the power of 555.18W, pH of 2.79, and time of 40.69 min with optimum desirability of 0.829, while for acid extraction, the temperature of 72.95°C, pH of 2.31, and time of 142.55 min with the desirability of 0.88. A highly functionalized pectin can be extracted from the peels of A. angustifolium as an alternate source.

Performance enhancement of up-flow anaerobic sludge blanket reactor for psychrophilic temperature during the dry season: Kality wastewater treatment plant

The main purpose of wastewater treatment plant (WWTP) is to reduce organic and inorganic pollutants to meet standards. But WWTPs employing up flow anaerobic sludge blanket (UASB) reactors under psychrophilic temperature are currently removing about 55% chemical oxygen demand (COD) and 70% total dissolved solids (TSS). The research was done to increase the treatment efficiencies of UASB reactor working under psychrophilic conditions through optimization of operational parameters like temperature, organic loading rate (OLR), pH and hydraulic retention time (HRT). Experimentation was carried out in a 0.0486 m3 square-shaped pilot-scale UASB reactor. Experimental design response surface method (RSM) for performance enhancement and optimization of UASB reactor operational parameters through five levels of central composite design (CCD) was used. The optimized operational parameters obtained from CCD-RSM were as follows: temperature of 21.58 °C, OLR of 2.99 kg COD/m3.d, HRT of 4.37hrs and pH of 6.3. Using optimized parameters, tests yielded efficiencies of 92.70%, 99.06%, and 94.50% for COD, TSS, and volatile suspended solid (VSS) respectively. The outlet concentrations of alkalinity, and volatile fatty acids (VFA), were found to be lower than the inlet concentrations. The alkalinity in the system accepts the hydrogen ion released by acids and the system is taken over by methanogensis to maintain the pH. The outlet concentration of sulfate ion was found to be increasing due to inhabitation of sulfur-reducing bacteria by an anaerobic condition of VFA and alkalinity at a pH less than 7.8.This process favors the production of CH4 than H2S gas. In general, there was a high likelihood of improving the performance of UASB reactor operating at psychrophilic temperature by optimizing operational parameters.

Molecularly imprinted polymers (MIPs) as efficient catalytic tools for the oxidative degradation of 4-nonylphenol and its by-products.

Water pollution is a current global concern caused by emerging pollutants like nonylphenol (NP). This endocrine disruptor cannot be efficiently removed with traditional wastewater treatment plants (WTPs). Therefore, this work aimed to evaluate the adsorption influence of molecularly imprinted polymers (MIPs) on the oxidative degradation (ozone and ultraviolet irradiations) of 4-nonylphenol (4-NP) and its by-products as a coadjuvant in WTPs. MIPs were synthesized and characterized; the effect of the degradation rate under system operating conditions was studied by Box-Behnken response surface design of experiments. The variables evaluated were 4-NP concentration, ozone exposure time, pH, and MIP amount. Results show that the MIPs synthesized by co-precipitation and bulk polymerizations obtained the highest retention rates (> 90%). The maximum adsorption capacities for 4-NP were 201.1mg L-1 and 500mg L-1, respectively. The degradation percentages under O3 and UV conditions reached 98-100% at 120s of exposure at different pHs. The degradation products of 4-NP were compounds with carboxylic and ketonic acids, and the MIP adsorption was between 50 and 60%. Our results present the first application of MIPs in oxidation processes for 4-NP, representing starting points for the use of highly selective materials to identify and remove emerging pollutants and their degradation by-products in environmental matrices.

Dialysis is a key factor modulating interactions between critical process parameters during the microfluidic preparation of lipid nanoparticles

Manufacturing lipid nanoparticles through microfluidic mixing can be approached from a Quality by Design perspective. Research involving critical process parameters seems to focus on the total flow and flow rate ratio, thus other process variables, such as dialysis, are underestimated. This study used a Design of Experiments to identify the influence of critical process parameters on particle size, polydispersity index, and zeta potential. A response surface Design of Experiments modeled the influence of: total flow (400 to 4000 μL min-1); flow rate ratio (3 to 9) and dialysis (yes/no). Results suggest that dialysis is a crucial parameter that strongly influences particle size and zeta potential and moderately affects polydispersity index. The flow rate ratio's relevance decreases when dialysis is performed. As the purification method can change the influence of other process parameters, it should be an integrated part of the microfluidic manufacturing of lipid nanoparticles instead of an extra step.

Impact of process parameters on the specific volume of wholemeal wheat bread made using sourdough- and baker's yeast-based leavening strategies

The final quality of wholemeal wheat bread is determined by the process parameter settings and leavening strategy. We hypothesise that the used leavening strategy may influence the optimal process parameter settings and, as such, the specific volume of the bread loaf. To analyse this interaction, bread was leavened with (i) a type 1 sourdough (SB), (ii) a type 1 sourdough combined with baker's yeast (YSB), or (iii) baker's yeast (YB). For each leavening strategy, the specific volume of bread, in response to variations in mixing time (4–10/4–14 min), water absorption (60–85 %), and proofing time (1–7/1–3 h), was analysed using an I-optimal response surface experimental design. Data modelling identified a substantially lower maximal specific volume of SB (2.13 mL/g), compared to YSB (3.30 mL/g) and YB (3.26 mL/g). The proofing time and water absorption mostly influenced the specific volume of the SB and YSB, respectively. However, the mixing and proofing times mainly affected the specific volume of YB. The type 1 sourdough reduced the mixing time and water absorption required for an optimal specific volume of bread compared to baker's yeast. These results challenge the idea of yielding higher volumes upon using sourdough compared to baker's yeast and highlight the importance of optimisation of bread dough formulations and breadmaking processes.

Influence of Cooling and Lubrication Parameters on Robot Bone Grinding Temperature and Prediction Modeling

In the process of robot bone grinding, a large amount of heat is generated, which will cause mechanical and thermal damage to bone tissues and nerves. It is necessary to study the influence of cooling and lubrication parameters on the robot bone grinding temperature and establish the prediction models among them. The FE model of single abrasive bone grinding was established to explore the influence of cooling and lubrication parameters on the bone grinding temperature. Response surface design of experiment was carried out to obtain the simulation results, and Design-Expert was used to establish a multiple regression prediction models of grinding temperature under the condition of different cooling and lubrication. Through the variance and response surface comparative analysis of the prediction model, the influence rules of the bone grinding parameters and the cooling and lubrication parameters on the bone grinding temperature was obtained. A robot bone grinding experiment was performed to prove the accuracy of FE simulation and prediction model. The research results show that the relationship between grinding temperature and cooling lubrication parameters obtained by FE simulation, RSM prediction and experiment verification is consistent, and the simulation model and prediction model of cooling and lubrication parameters are proven to be correct and effective. The influence rules and prediction effects obtained in this study will provide a reasonable scheme for doctors to implement robot bone grinding with high efficiency and low damage, and establish the theoretical basis for the effective control of robot bone grinding force thermal damage.

Optimization of the Epimedii Folium Mutton-Oil Processing Technology and Testing Its Effect on Zebrafish Embryonic Development.

As a traditional Chinese medicine (TCM), Epimedii folium (EF) has a history in medicine and food that is > 2,000 years old. Clinically, EF processed with mutton oil is often used as a medicine. In recent years, reports of safety risks and adverse reactions of products that use EF as a raw material have gradually increased. Processing can effectively improve the safety of TCM. According to TCM theory, mutton-oil processing can reduce the toxicity of EF and enhance its tonifying effect on the kidneys. However, there is a lack of systematic research and evaluation of EF mutton-oil processing technology. In this study, we used the Box-Behnken experimental design-response surface methodology to optimize the key parameters of the processing technology by assessing the contents of multiple components. The results showed that the optimal mutton-oil processing technology of EF was as follows: heating the mutton oil at 120 °C ± 10 °C, adding the crude EF, stir-frying it gently to 189 °C ± 10 °C until it is evenly shiny, and then removing it and cool. For every 100 kg of EF, 15 kg of mutton oil should be used. The toxicities and teratogenicities of an aqueous extract of crude and mutton-oil processed EF were compared in a zebrafish embryo developmental model. The results showed that the crude herb group was more likely to cause zebrafish deformities, and its half-maximal lethal EF concentration was lower. In conclusion, the optimized mutton-oil processing technology was stable and reliable, with good repeatability. At a certain dose, the aqueous extract of EF was toxic to the development of zebrafish embryos, and the toxicity was stronger for the crude drug than for the processed drug. The results showed that mutton-oil processing reduced the toxicity of crude EF. These findings can be used to improve the quality, uniformity, and clinical safety of mutton oil-processed EF.

Modelling and Optimizing the Effect of pH on Remediation of Crude Oil Polluted Soil with Biochar Blend: RSM Approach

This research modelled the effect of pH on the remediation of crude oil-polluted soil using biochar blend. The biochar blends, PL-500, pW-500, and RS-400, were made by pyrolyzing poultry litter, pine wood, and rice straw at varied temperatures and times. The pH of the crude oil polluted soil was 4.72. Response surface experimental design mixed biochar to remediate total petroleum hydrocarbons (TPH). Following 30 days of bioremediation, 15g PL-500, 3g PW-500 and 6g RS-400, removed a maximum of 46% TPH. The experimental data were statistically modelled and optimized using design expert software and response surface methods. Analysis of variance (ANOVA) was used to determine the significance of each regression coefficient. Biochar blend improved soil pH to 6.9 following remediation. ANOVA indicated that PL-500 was significant for predicting TPH % degradation at p =0.0290, suggesting that its high pH, nutrient, and soil water conservation values made it more effective in remediating TPH. The quadratic model predicts with R2 =0.8567. A model fit statistics were used to examine soil pH influence on TPH remediation. RSM study indicated a good positive association between statistical model and experiment with R2 = 0.7612. The model fits experimental data and predicts that . Remediation requires soil pH and biochar's alkalinity raised soil pH to 6.9, which promoted hydrocarbon-utilizing bacteria.

Inactivation of Listeria monocytogenes by pulsed light in packaged and sliced salpicão, a ready-to-eat traditional cured smoked meat sausage

The efficacy of pulsed light (PL) for the surface decontamination of a sliced ready-to-eat cured meat product, salpicão, was studied. The surface of the slices was inoculated with Listeria monocytogenes (107 cfu/g), and then PL treatment was applied. Microbial analyses (L. monocytogenes, coagulase-negative Staphylococci (CNS), Lactic acid bacteria (LAB) and Enterobacteriaceae) were performed immediately after the treatment. pH, aw, colour and volatile profile were also evaluated. Response Surface experimental Design was applied regarding factors voltage (ranging from 1828 to 3000 V) and distance (ranging from 2.6 to 5 cm) to the light source, and a maximum of 16.11 J/cm2 energy dose was achieved. A reduction of 1.58 log cfu/g in L. monocytogenes count was obtained when a fluence of 5.31 J/cm2 was applied. Enterobacteriaceae, LAB and CNS endogenous microbial populations were not influenced by PL treatment. PL application reduced a* values and influenced b* values without impacting the sample ΔE or L* values. The potential oxidative effect of this technology was evaluated by solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS), and no significant changes were verified after its application in this sliced cured meat product.