Tyrosinase-based nanobiosensor for environmental monitoring of hormones in river water.

This study explores the application of a tyrosinase cantilever nanobiosensor for detecting 17ß-estradiol and estrone in typical water systems. The physical-chemical parameters of water were evaluated within the Tigre River micro-basin in Erechim, RS, to determine water potability for urban populations. Water clarity, conductivity, and pH levels were essential markers, adhering to recognized standards for water quality and human consumption. The cantilever nanobiosensor demonstrated strong sensitivity and a broad linear range, with a limit of detection (<0.00051 ppb) surpassing other enzymatic biosensors and covering a range of 0.0001-100 ppb. The real water sample quality investigated in relation to contamination with 17ß-estradiol and estrone by nanobiosensor showed values below the LOD for both compounds. Recovery studies demonstrated the reliability of the nanobiosensor. Selectivity tests indicated minimal interference from structurally similar substances. This study validates the nanobiosensor's potential for environmental monitoring and hormone detection, aligning with standard practices.

Antioxidant activity of rosemary extract, acerola extract and a mixture of tocopherols in sausage during storage at 8 °C.

Sausage is an emulsified meat product that, due to its composition, undergoes physicochemical changes during its shelf life, which makes the use of additives for its conservation necessary. The goal of the present study was to evaluate the antioxidant capacity of rosemary extract, acerola extract, and a mixture of tocopherols applied to industrialized sausages during storage at 8 °C. The antioxidant activity (IC50) in vitro showed values of 0.043, 0.489, 0.494, and 0.509 mg/mL for sodium erythorbate, rosemary extract, acerola extract, and a mixture of tocopherols, respectively. Formulations of sausage obtained in industrial installations were evaluated in terms of physicochemical, microbiological, and sensorial analyses. The pH and acidity values were stable during 23 days of storage. Treatments 1 and 3 with acerola extract and a mixture of tocopherols associated with sodium erythorbate showed the best results against lipid oxidation (TBARs), respectively. The hydroperoxides were only found after the 12th day of storage, consequently reducing the formation of malondialdehyde. The treatments with natural antioxidants showed an antimicrobial effect for the group of mesophilic bacteria; their results did not exceed 4 log10 CFU/g, while the control reached 5 log10 CFU/g on the 23rd day of storage. In regard to other microorganisms evaluated, no significant differences were found between treatments with natural antioxidants. Thus, the natural extracts evaluated in association with sodium erythorbate contributed to the antioxidant action for the application on an industrial scale, as they improved the sausage characteristics after 23 days of storage at 8 °C. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05815-y.

Purification, bioactivity and application of maltobionic acid in active films.

The objective of this study was to purify sodium maltobionate using Zymomonas mobilis cells immobilized in situ on flexible polyurethane (PU) and convert it into maltobionic acid for further evaluation of bioactivity (iron chelating ability, antibacterial potential and cytoprotection) and incorporation into films based on cassava starch, chitosan, and cellulose acetate. Sodium maltobionate exhibited a purity of 98.1% and demonstrated an iron chelating ability of approximately 50% at concentrations ranging from 15 to 20 mg mL-1. Maltobionic acid displayed minimal inhibitory concentrations (MIC) of 8.5, 10.5, 8.0, and 8.0 mg mL-1 for Salmonella enterica serovar Choleraesuis, Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes, respectively. Maltobionic acid did not exhibit cytotoxicity in HEK-293 cells at concentrations up to 500 µg mL-1. Films incorporating 7.5% maltobionic acid into cassava starch and chitosan demonstrated inhibition of microbial growth, with halo sizes ranging from 15.67 to 22.33 mm. These films had a thickness of 0.17 and 0.13 mm, water solubility of 62.68% and 78.85%, and oil solubility of 6.23% and 11.91%, respectively. The cellulose acetate film exhibited a non-uniform visual appearance due to the low solubility of maltobionic acid in acetone. Mechanical and optical properties were enhanced with the addition of maltobionic acid to chitosan and cassava films. The chitosan film with 7.5% maltobionic acid demonstrated higher tensile strength (30.3 MPa) and elongation at break (9.0%). In contrast, the cassava starch film exhibited a high elastic modulus (1.7). Overall, maltobionic acid, with its antibacterial activity, holds promise for applications in active films suitable for food packaging. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03879-3.

Differentiating True and False Cinnamon: Exploring Multiple Approaches for Discrimination.

This study presents a comprehensive literature review that investigates the distinctions between true and false cinnamon. Given the intricate compositions of essential oils (EOs), various discrimination approaches were explored to ensure quality, safety, and authenticity, thereby establishing consumer confidence. Through the utilization of physical-chemical and instrumental analyses, the purity of EOs was evaluated via qualitative and quantitative assessments, enabling the identification of constituents or compounds within the oils. Consequently, a diverse array of techniques has been documented, encompassing organoleptic, physical, chemical, and instrumental methodologies, such as spectroscopic and chromatographic methods. Electronic noses (e-noses) exhibit significant potential for identifying cinnamon adulteration, presenting a rapid, non-destructive, and cost-effective approach. Leveraging their capability to detect and analyze volatile organic compound (VOC) profiles, e-noses can contribute to ensuring authenticity and quality in the food and fragrance industries. Continued research and development efforts in this domain will assuredly augment the capacities of this promising avenue, which is the utilization of Artificial Intelligence (AI) and Machine Learning (ML) algorithms in conjunction with spectroscopic data to combat cinnamon adulteration.

Kinetic and stoichiometric parameters in the fed-batch bioreactor production of poly(3-hydroxybutyrate) by Bacillus megaterium using different carbon sources.

This study investigates the effects of different strategies on poly(3-hydroxybutyrate)-P(3HB) production in a fed-batch bioreactor by Bacillus megaterium using candy industry effluent (CIE), sucrose, and rice parboiled water (RPW) as carbon sources. In biosynthesis, kinetic and stoichiometric parameters of substrate conversion into products and/or cells, productivity, instantaneous, and specific conversion rates were evaluated. The maximum concentration of P(3HB) was 4.00 g.L-1 (77% of the total dry mass) in 42 h of cultivation in minimal medium/RPW added with a carbon source based on CIE, demonstrating that the fed-batch provided an increase of approximately 22% in the polymer concentration and 32% in the overall productivity in relation to medium based on commercial sucrose. Fed-batch cultivation also had the advantage of avoiding the extra time required for inoculum preparation and sterilization of the bioreactor during the batch, which thereby increased the overall industrial importance of the process. Effluents from the candy, confectionery, and/or rice parboiling industries can be used as alternative substrates for P(3HB) production at a low cost.

Influence of redox potential on the accumulation of poly(3-hydroxybutyrate) by Bacillus megaterium.

The main goal of the present study was to evaluate the oxidation-reduction potential (ORP) on the production of poly(3-hydroxybutyrate) (P(3HB)) by Bacillus megaterium. Each microorganism has an optimal ORP range, and changes to the culture medium's ORP may redistribute the cell's metabolic flux, as such, the measurement and control of the ORP profile allows one to, in a way, manipulate the microbial metabolism, affecting the expression of certain enzymes and allowing for better control over the fermentative process. The ORP tests were carried out in a fermentation vessel coupled with an ORP probe, containing 1 L of mineral medium added with agroindustry byproducts (60% v/v of confectionery wastewater, and 40% v/v of rice parboiling water). The system's temperature was kept at 30 °C, with an agitation speed of 500 rpm. The vessel's airflow rate was controlled via a solenoid pump based on the ORP probe's data. Different ORP values were evaluated to verify their impact on biomass and polymer production. Cultures using OPR levels of 0 mV displayed the highest amounts of total biomass (5.00 g L-1) when compared to - 20 mV and - 40 mV (2.90 g L-1 and 0.53 g L-1, respectively). Similar results were also found for P(3HB)-to-biomass ratio, with polymer concentration being reduced when using ORP levels below 0 mV and with a maximum amount of polymer-to-biomass ratio of 69.87% after 48 h of culture. Furthermore, it was possible to observe that the culture's pH can also affect total biomass and polymer concentration, albeit to a lesser extent. Thus, when considering the data found during this study, it is possible to observe that ORP values can greatly impact B. megaterium cell's metabolism. Furthermore, the measurement and control of ORP levels may be an invaluable asset when trying to maximize polymer production under different culture conditions.

Antifungal activity and aroma persistence of free and encapsulated Cinnamomum cassia essential oil in maize.

The objective of this study was to evaluate the chemical composition and antifungal activity of free and encapsulated Cinnamomum cassia essential oil (EO) against Penicillium crustosum, Alternaria alternata, and Aspergillus flavus, and the aroma persistence in maize flour. Trans-cinnamaldehyde (TC) was identified as the major compound (86 %) in the C. cassia EO. The EO was encapsulated by spray-dryer with 45.26 % efficiency using gum arabic (GA) and maltodextrin (MD) in a ratio of 1:1 (m/m). C. cassia EO showed antifungal activity against A. alternata, A. flavus, and P. crustosum, with a minimum inhibitory concentration (MIC) of 0.5 % for both free and standard TC, and 5 % for the encapsulated EO. Fungal growth inhibition was evaluated under exposition to vapors at different concentrations of C. cassia EO and TC standard, with MIC of 6 % and 8 % against P. crustosum, 4 % and 1 % A. alternata, and 4 % A. flavus, respectively. The sensory analysis results of the free and encapsulated C. cassia EO in maize flour showed a significant difference between the treated samples in relation to the standard sample (p < 0.05). The sample with free EO has high aroma intensity persistence, while the samples treated with encapsulated EO were evaluated as being closer to the standard sample. The results suggest that the encapsulated C. cassia EOs can be used as natural alternatives to control fungi in maize flour.

Technological characteristics of tofu from soybean coagulated with cardoon flower extract.

The objective of the present study was to develop tofu with soybean-water soluble extract coagulated with cardoon flower (F1) and magnesium chloride (MgCl2, F2). The produced tofu was characterized in terms of physical, chemical, microbiological, and sensory properties during 14 days of storage. The yield of F1 was higher (p < 0.05) (195 g/100 soybean seeds) than F2 (162 g/100 soybean seeds). F1 presented higher moisture, protein, acidity, syneresis, and lipids when compared with F2, and a reduction of these contents during the storage. F1 presented lower hardness, stickiness, springiness, and cohesiveness compared with F2. The acceptability of F1 showed a score of 6.00 and F2 of 4.68, and the purchase intention was 3.22 for F1 and 2.23 for F2. This study recommended the use of cardoon flower at 35% level as it has great potential as a coagulant for the elaboration of tofu with higher yield, and acceptability and reasonable purchasing intention.

Lamivudine and Zidovudine-Loaded Nanostructures: Green Chemistry Preparation for Pediatric Oral Administration.

Here, we report on the development of lipid-based nanostructures containing zidovudine (1 mg/mL) and lamivudine (0.5 mg/mL) for oral administration in the pediatric population, eliminating the use of organic solvents, which is in accordance with green chemistry principles. The formulations were obtained by ultrasonication using monoolein (MN) or phytantriol (PN), which presented narrow size distributions with similar mean particle sizes (~150 nm) determined by laser diffraction. The zeta potential and the pH values of the formulations were around -4.0 mV and 6.0, respectively. MN presented a slightly higher incorporation rate compared to PN. Nanoemulsions were obtained when using monoolein, while cubosomes were obtained when using phytantriol, as confirmed by Small-Angle X-ray Scattering. The formulations enabled drug release control and protection against acid degradation. The drug incorporation was effective and the analyses using an electronic tongue indicated a difference in palatability between the nanotechnological samples in comparison with the drug solutions. In conclusion, PN was considered to have the strongest potential as a novel oral formulation for pediatric HIV treatment.

Evaluation of packaging systems with O2-absorbers on quality of minimally processed soybean sprouts.

This study evaluated the influence of O2-absorbing sachets into different packages polyethylene terephthalate (PET - E1), low density polyethylene (LDPE - E2), and PET/LDPE (E3) on the quality of minimally processed soybean sprouts (MP-sprouts). The MP-sprouts were stored up to 12 days and characterized for physicochemical, microbiological and sensory attributes. The O2-absorbing sachet showed changes during exposure to the environment by the formation of amorphous iron hydroxide, which was observed by the analysis of functional groups and XRD. The packaging used in the study showed high transmittance and clarity, and low Haze, being a good feature for storing the MP product. All packaging systems showed an increase in the volume of absorbed oxygen (cm3) up to 9 days of storage. The physic-chemical characteristics of the MP-sprouts stored for 12 days were preserved in the different packages, showing no difference regarding the use of the O2-absorbing sachet. The O2-absorbing sachet not influenced the quality of MP-sprouts during the stored (12 days). The best visual aspect was observed in PET package (with and without O2-absorbing sachet) being classified as excellent, without color change. The MP-sprouts also fulfilled the microbiological quality standards and presented 75.11% acceptability and 72.40% purchase intention.

Caracterização físico-química da farinha e dos extratos das sementes de abacate (Persea americana (Mill.) Lauraceae)

Introdução: as indústrias de processamento de frutas geram grande quantidade de biomassa residual que poderia ser reaproveitada. Considerando o elevado volume de resíduos produzidos pelo descarte das sementes do abacate e destacando o alto teor de compostos bioativos, é um produto interessante para ser avaliado. Objetivo: avaliar a composição centesimal da farinha das sementes de abacate e as propriedades antioxidantes e antimicrobianos dos seus extratos. Métodos: os extratos foram obtidos por maceração da farinha do caroço do abacate desidratada em diferentes temperaturas (4,25 e 60 °C) utilizando n-hexano e etanol como solventes. Resultados: verificou-se que a farinha é uma excelente fonte de carboidratos, com alto teor de fibras, proteínas e minerais (N, K, Mg e Ca, entre outros). A temperatura da extração influenciou tanto no rendimento como no conteúdo de fenóis totais, atividades antioxidantes e antimicrobianas dos extratos. Os extratos etanoicos obtidos à 60 °C apresentaram maior rendimento (18%) e teor de compostos fenólicos totais (~840 mgEAG/g). Também os extratos etanoicos apresentaram maior atividade antioxidante (IC50= 0,013 mg/mL e 0,018 mg/mL) em temperaturas mais baixas de extração, 4 °C e 25 °C, respectivamente. Já extrato hexanóico obtido à 4 °C apresentou maior atividade antimicrobiana para as quatro bactérias testadas (L. monocytogenes, S. aureus, S. choleraesuis e E. coli). Conclusão: a farinha obtida das sementes de abacate, apresentam alto valor biológico e podem ser usadas como suplementos na alimentação humana.

SUMMARY Introduction: The fruit processing industries generate a large amount of residual biomass that could be reused. Considering the high volume of residues produced by the disposal of avocado seeds and highlighting the high content of bioactive compounds. Aim: To evaluate the centesimal composition of avocado seed flour and the antioxidant and antimicrobial properties of its extracts. Methodology: The extracts were obtained by macerating the avocado seed flour dehydrated at different temperatures (4,25 and 60 °C) using n-hexane and ethanol as solvents. Results: The flour is an excellent source of carbohydrates, with a high content of fibers, proteins and minerals (N, K, Mg and Ca, among others). The extraction temperature has influence in the yield and the content of total phenols, antioxidant and antimicrobial activities of the extracts. The ethanolic extracts obtained at 60 °C showed high yield (18%) and content of total phenolic compounds (~840 mg GAE/g). In addition, ethanol extracts showed high antioxidant activity (IC50= 0.013 mg/mL and 0.018 mg/mL) at lower extraction temperatures, 4 °C and 25 °C, respectively. Hexanoic extract obtained at 4 °C, on the other hand, showed greater antimicrobial activity for the four tested bacteria (L. monocytogenes, S. aureus, S. choleraesuis and E. coli). Conclusion: The flour obtained from avocado seeds has a high biological value and can be used as supplements in human food.

Introducción: las industrias de procesamiento de frutas generan una gran cantidad de biomasa residual que podría reutilizarse. Considerando el alto volumen de residuos que produce la disposición de semillas de aguacate y destacando el alto contenido de compuestos bioactivos. Objetivo: evaluar la composición centesimal de la harina de semilla de aguacate y las propiedades antioxidantes y antimicrobianas de sus extractos. Metodología: los extractos se obtuvieron macerando la harina de semilla de aguacate deshidratada a diferentes temperaturas (4, 25 y 60 °C) utilizando n-hexano y etanol como solventes. Resultados: la harina es una excelente fuente de carbohidratos, con un alto contenido en fibras, proteínas y minerales (N, K, Mg y Ca, entre otros). La temperatura de extracción influye en el rendimiento y el contenido de fenoles totales, actividades antioxidantes y antimicrobianas de los extractos. Los extractos etanólicos obtenidos a 60 °C mostraron alto rendimiento (18%) y contenido de compuestos fenólicos totales (~ 840 mg GAE/g). Además, los extractos de etanol mostraron una alta actividad antioxidante (IC50 = 0,013 mg/mL y 0,018 mg/mL) a temperaturas de extracción más bajas, 4 °C y 25 °C, respectivamente. El extracto hexano obtenido a 4 °C, en cambio, mostró mayor actividad antimicrobiana para las cuatro bacterias ensayadas (L. monocytogenes, S. aureus, S. choleraesuis y E. coli). Conclusión: la harina obtenida a partir de semillas de aguacate tiene un alto valor biológico y puede ser utilizada como complemento en la alimentación humana.

Correction: Sexual pheromone detection using PANI·Ag nanohybrid and PANI/PSS nanocomposite nanosensors.

Correction for 'Sexual pheromone detection using PANI·Ag nanohybrid and PANI/PSS nanocomposite nanosensors' by Janine Martinazzo et al., Anal. Methods, 2021, 13, 3900-3908, DOI: 10.1039/d1ay00987g.

Sexual pheromone detection using PANI·Ag nanohybrid and PANI/PSS nanocomposite nanosensors.

In this study, polyaniline/poly(styrene sulfonate) (PANI/PSS) nanocomposite and polyaniline·silver (PANI·Ag) nanohybrid thin films were obtained in cantilever nanosensors surface. The developed films were characterized in relation to topography, roughness, thickness, height, and structural properties. The topography study revealed that both films have a globular morphology, thickness and height in nanoscale. The gas sensing performance was investigated for sexual pheromone from the neotropical brown stink bug, Euschistus heros (F.). The sensitivities of both nanosensors based on PANI/PSS nanocomposite and PANI·Ag nanohybrid films were similar. The PANI·Ag nanohybrid nanosensor had a limit of detection of less than 3.1 ppq and limit of quantification of 10.05 ppq. The nanosensor layers were analyzed by UV-vis and FTIR showing the incorporation of Ag nanoparticles in the nanohybrid. We found that pheromone compound was adsorbed in sensing layer resulting in a reduction in the resonance frequency. The detection mechanism help us understand the good results of LOD, LOQ, sensitivity, selectivity and repeatability. The presented device has great potential for detection of the sexual pheromone from E. heros.

Degradation of micropollutant cephalexin by ultraviolet (UV) and assessment of residual antimicrobial activity of transformation products.

Cephalexin (CEX) is an antibiotic commonly used to treat bacterial infections in humans and animals. However, it is also a micropollutant. Thus, this study evaluated the degradation of CEX using ultraviolet irradiation (UV-C) and analyzed the by-products as well as their residual antimicrobial activity. A reactor with a mercury vapor lamp was used for the degradation. Irradiated CEX solutions were collected over a period of 4 hours and analyzed using high-performance liquid chromatography coupled with mass spectrometry. For the residual antimicrobial activity the susceptibility test was performed using Staphylococcus aureus and Escherichia coli microorganisms by broth microdilution. It was found that CEX, after treatment, generated a metabolite with a mass of 150 m/z in 15 min. A four- and eightfold increase in the minimum inhibitory concentration of the drug against S. aureus and E. coli could be observed, respectively, after 20 min. Therefore, this treatment proved to be effective in the degradation of CEX, being able to degrade 81% of the initial molecule of the drug in 20 min. Furthermore, the antimicrobial activity of the CEX solution decreased as the irradiation time increased, indicating loss of antimicrobial function of the initial CEX molecule and the resulting by-products.

Electronic Nose Based on Carbon Nanocomposite Sensors for Clove Essential Oil Detection.

This work describes the development of an electronic nose (e-nose) based on carbon nanocomposites to detect clove essential oil (CEO), eugenol (EUG), and eugenyl acetate (EUG.ACET). Our e-nose system comprises an array of six sensing units modified with nanocomposites of poly(aniline), graphene oxide, and multiwalled carbon nanotubes doped with different acids, dodecyl benzene sulfonic acid, camphorsulfonic acid, and hydrochloric acid. The e-nose presented an excellent analytical performance to the detected analytes (CEO, EUG, and EUG.ACET) with high sensitivity and reversibility. The limit of detection was lower than 1.045 ppb, with response time (<13.26 s) and recovery time (<106.29 s) and low hysteresis. Information visualization methods (PCA and IDMAP) demonstrated that the e-nose was efficient to discriminate the different concentrations of analyte volatile oil compounds. PM-IRRAS measurements suggest that the doping mechanism of molecular architectures is composed of a change in the oscillation energy of the characteristic dipoles and changes in the molecular orientation dipoles C═C and C═O at 1615 and 1740 cm-1, respectively. The experimental results indicate that our e-nose system is promising for a rapid analysis method to monitor the quality of essential oils.

Interfacial and emulsifying properties of whey protein concentrate by ultrafiltration.

The aim of this study was to concentrate whey protein by ultrafiltration process, evaluating the pressure at 1-3 bar and temperature of 10-20℃. In the conditions that show the more protein concentration were evaluated the interfacial and emulsifying properties at pH 5.7 and 7.0. The whey concentrate at 10℃ and 1.5 bar showed the higher protein value 36% (w/w), with soluble protein of 33.82% (solubility of 93.94%) for pH 5.7 and 34% (solubility of 94.4%) for pH 7.0, respectively. The whey concentrate powder present particle size distribution between 0.4-110 um. The whey at pH 5.7 and 7.0 was not observed significant differences in the resistance parameters of the oil/water layer interface. The interfacial film formed by the proteins presented an essentially elastic behavior in both pH, and in pH 5.7 the emulsion was more stable with lower diameter droplets. The concentrate whey showed techno-functional properties (emulsification and solubility), which allow the use as ingredients in products of industrial interest in food products such as mayonnaise, ice cream, sauces, and others.

Cantilever Nanobiosensor Functionalized with Tyrosinase for Detection of Estrone and ß-estradiol in Water.

This work aimed to develop cantilever nanobiosensor functionalized with tyrosinase enzyme to detect 17ß-estradiol and estrone hormones. In this system, the tyrosinase enzyme was covalently immobilized by self-assembled monolayer onto the cantilever sensor surface. It was possible to verify that the high hormone concentration investigated resulted in high voltage response. The nanobiosensor presented a distinction between the concentrations evaluated and was verified sensitivities of 0.497 and 0.101 V/µg, limit of detection of 0.1 and 0.4 ng/L for the hormones 17ß-estradiol and estrone, respectively. The device showed good reversibility and during 30 days of storage maintained about 99% of the original signal. The cantilever nanobiosensor applied in different water samples (ultrapure, river, tap, and mineral) showed good performance, so could be readily extended toward the on-site monitoring of the other trace small molecular pollutants in environmental water matrices.

Heavy metals detection in river water with cantilever nanobiosensor.

Heavy metals can be highly toxic depending on the dose and the chemical form. In this context, sensing devices such as nanobiosensors have been presented as a promising tool to monitor contaminants at micro and nanoscale. In this work, cantilever nanobiosensors with phosphatase alkaline were developed and applied to detect heavy metals (Pb, Ni, Cd, Zn, Co, and Al) in river water. The nanobiosensor surface was functionalized by the self-assembled monolayers (SAM) technique using 16-mercaptohexadecanoic acid, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N- hydroxysuccinimide (NHS), and phosphatase alkaline enzyme. The sensing layer deposited on the cantilever surface presented a uniform morphology, at nanoscale, with 80 nm of thickness. The nanobiosensor showed a detection limit in the ppb range and high sensitivity, with a stability of fifteen days. The developed cantilever nanobiosensor is a simple tool, suitable for the direct detection of contaminants in river water.

Production of Ethyl Esters by Direct Transesterification of Microalga Biomass Using Propane as Pressurized Fluid.

This work aimed to produce ethyl esters from Chlorella vulgaris microalgae biomass, using an immobilized enzymatic catalyst associated with pressurized fluid (propane) by direct transesterification. In order to optimize the ethyl conversion, different temperatures (46.7-68.1 °C) and pressures (59.5-200.5 bar) were applied a central composite design rotational (CCDR) obtaining the high conversion (74.39%) at 50 °C and 180 bar. The molar ratio also was investigated showing conversions ~ 90% using a molar ratio of 1:24 (oil:ethanol). From the best transesterification conditions, 50 °C, 180 bar, 20% enzymatic concentration, and 1:24 oil:ethanol molar ratio were obtained with success 98.9% conversion in 7 h of reaction. The enzyme reuse maintained its activity for three successive cycles. Thus, this simple process was effective to convert microalgal biomass into ethyl ester by direct transesterification and demonstrate high yields.

Linseed (Linum usitatissimum) Oil Extraction Using Different Solvents.

This work aims at characterizing linseed oil obtained using different extraction methods (hexane, subcritical propane and pressurized ethanol), and comparing the results with commercial linseed oil extracted by cold mechanical press method. An experimental design helped to evaluate temperature and pressure effects on the oil extraction using propane and ethanol. Gas chromatography assisted in evaluating the essential fatty acids. There were no significant differences among the ω-3, 6 and 9 fatty acids from linseed oil obtained using the different extraction methods. Only the acidity of linseed oil extracted by subcritical propane (0.956%) showed significant differences among the physicochemical parameters. Extraction using organic solvent (Soxhlet) gave a 36.12% yield. Extraction using subcritical propane at 107 Pa and 40 °C for 1.5 h gave a better yield (28.39%) than pressurized ethanol (8.05%) under similar conditions. Linseed oil extraction using subcritical propane was economically viable, resulting in a 124.58 US$/L product cost. The results present subcritical propane extraction as a promising alternative for obtaining linseed oil at mild temperature and pressure conditions, without losing quality and quantity of fatty acids such as ω-3, 6 and 9.