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.

Lab-made electronic-nose with polyaniline sensor array used in classification of different aromas in gummy candies.

Aroma is closely related to the food product acceptability and an important product quality indicator. Electronic-nose (E-nose) systems are an interesting alternative to traditional methods of aroma analyses. A lab-made E-nose system equipped with an array of sensing units comprised by gold interdigitated microelectrodes (IDEs) using polyaniline (Pani) as sensitive layers deposited by the in situ and Layer-by-layer (LbL) methods was used to analyze aromas in gummy candies. Different concentrations from artificial aromas (apple, strawberry and grape), added to the gummy candies were evaluated. Our system presented 21.6 mV.ppb-1 sensitivity, ppb range detection limit, and good reversibility, around 97.6%. The sensitive layers of Pani films was adequate deposited on IDEs observed by the Attenuated Total Reflection/Fourier-transform infrared spectroscopy (ATR/FTIR). Linear Discriminant Analysis (LDA) was able to classify apple, strawberry, and grape aromas added to gummy candies using saturation potential values from the E-nose system, demonstrating its applicability in food matrices.

Use of pervaporation process for the recovery of aroma compounds produced by P. fermentans in sugarcane molasses.

Natural fruity aroma was produced during submerged fermentation by Pichia fermentans using sugarcane molasses as a cultivation broth. The aroma compounds were recovered from the fermentation by a pervaporation process using a polydimethylsiloxane membrane (Pervap 4060-Sulzer). Isoamyl acetate, a characteristic compound associated with fruity aromas, was the major compound produced. The pervaporation module was fed at three different temperatures to test the best conditions to recover the natural fruity aroma. The total flux (J T), partial fluxes of each component (J i), and enrichment factors (ß) were determined within the tested ranges. The process was performed at 45 °C, a feed flow of 1.5 mL/min and 0.1 kPa, for a duration of 13 h to concentrate the natural flavor. The pervaporation process can concentrate the isoamyl acetate from fermented broth from 9 to 61.8 mg/L in the first hour of pervaporation. As a single step of downstream operation, pervaporation was efficient for recovering and concentrating the natural fruity aroma. The obtained product was colorless and had a characteristic banana flavor.

Mathematical model of the binding of allosteric effectors to the Escherichia coli PII signal transduction protein GlnB.

PII proteins are important regulators of nitrogen metabolism in a wide variety of organisms: the binding of the allosteric effectors ATP, ADP, and 2-oxoglutarate (2-OG) to PII proteins affects their ability to interact with target proteins. We modeled the simultaneous binding of ATP, ADP, and 2-OG to one PII protein, namely GlnB of Escherichia coli, using a modeling approach that allows the prediction of the proportions of individual binding states. Four models with different binding rules were compared. We selected one of these models (that assumes that the binding of the first nucleotide to GlnB makes it harder for subsequent nucleotides to bind) and used it to explore how physiological concentrations of ATP, ADP, and 2-OG would affect the proportions of those states of GlnB that interact with the target proteins ATase and NtrB. Our simulations indicate that GlnB can, as suggested by previous researchers, act as a sensor of both 2-OG and the ATP:ADP ratio. We conclude that our modeling approach will be an important tool in future studies concerning the PII binding states and their interactions with target proteins.