Efficient and low-cost alternative of lipase concentration aiming at the application in the treatment of waste cooking oils.

In this study, we evaluated the concentration of lipases from Aspergillus niger using efficient and low-cost methods aiming at application in the treatment of waste cooking oils. The change in ionic strength of the medium by the addition of salt and precipitation with ethanol increased the specific activity from 2.90 to 28.50 U/mg, resulting in a purification factor of 9.82-fold. The use of acetone resulted in a specific activity of 33.63 U/mg, resulting in a purification factor of 11.60-fold. After that, the concentrated lipase was used in the hydrolysis of waste cooking oil and 753.07 and 421.60 µmol/mL of free fatty acids were obtained for the enzyme precipitated with ethanol and acetone, respectively. The hydrolysis of waste cooking oil catalyzed by homemade purified lipase in ultrasonic media can be considered a pretreatment of oil by converting a significant amount of triglycerides into free fatty acids.

Purification of inulinases by changing the ionic strength of the medium and precipitation with alcohols.

The present study evaluated the purification of inulinase by changing the ionic strength of the medium by addition of NaCl and CaCl2 followed by precipitation with n-propyl alcohol or iso-propyl alcohol. The effects of the concentration of alcohols and the rate of addition of alcohols in the crude extract on the purification yield and purification factor were evaluated. Precipitation caused an activation of enzyme and allowed purification factors up to 2.4-fold for both alcohols. The purification factor was affected positively by the modification of the ionic strength of the medium to 0.5 mol.L-1 NaCl before precipitation with the alcohol (n-propyl or iso-propyl). A purification factor of 4.8-fold and an enzyme yield of 78.1 % could be achieved by the addition of 0.5 mol.L-1 of NaCl to the crude extract, followed by the precipitation with 50 % (v/v) of n-propyl alcohol, added at a flow rate of 19.9 mL/min.

Characterization of a commercial cellulase for hydrolysis of agroindustrial substrates.

This work is focused on the characterization of a commercial cellulase in terms of optimum pH and temperature, stability to pH and temperature and affinity of this enzyme to several substrates, determining the Michaelis-Menten parameters. Maximum activity of cellulase was obtained for the temperature range from 40 to 50 °C and pH from 5.2 to 5.5. Enzyme activity decreased only 15% after 150 h of reaction at temperatures between 30 and 50 °C. No loss of activity was observed at pH 5.0 and 5.5. The cellulase showed satisfactory results in the hydrolysis of agroindustrial substrates, since similar activity was verified on filter paper and other agroindustrial substrates.

Insecticidal and repellency activity of essential oil of Eucalyptus sp. against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae).

BACKGROUND: The objective of this work was to evaluate the insecticidal and repellent effect of essential oils of Eucalyptus dunnii, E. saligna, E. benthamii, E. globulus and E. viminalis in the control of Sitophilus zeamais in maize grains. RESULTS: The essential oils chemical composition showed that the E. benthamii presents the cis-ocimene (56.88%) as major compound. Results permitted us to verify that the evaluated species presented different insecticidal action under Sitophilus zeamais. About 100% of mortality was achieved with doses of 65, 100 and 400 microL for E. dunnii, E. saligna and E. benthamii, respectively. After regression analysis the LD(50) values were calculated and E. dunnii was shown to be the most efficient (25.03 microL), followed by E. saligna (37.93 microL) and E. benthamii (121.09 microL). Using the previously calculated LD(50) values, the repellency activity was calculated, allowing us to conclude that all species presented significant values in terms of this important parameter. CONCLUSION: The essential oil of Eucalyptus sp. presented insecticidal and repellency against Sitophilus zeamais Motschulsky (Coleoptera, Curculionidae). Although from an economic point of view synthetic chemicals are still more frequently used as repellents, natural products (essential oils) have the potential to provide efficient and safer repellents for humans and the environment.

Extraction and characterization of volatile compounds in Maytenus ilicifolia, using high-pressure CO2.

This work is focused on the chemical characterization of Maytenus ilicifolia extracts obtained from high-pressure CO2 extraction. The experiments were performed in a laboratory-scale unit, where the effect of particle size (35-200 mesh), CO2 mass flow rate (1-3 g/min), temperature (293-323 K), pressure (100-250 bar), and extraction time was investigated in terms of liquid yield and chemical composition of the extracts. Results show that the particle size and CO2 mass flow rate did not affect the liquid yield, whereas the extraction temperature and solvent density exerted a pronounced effect on both liquid yield and chemical distribution of volatile compounds. The extracts were chemically analyzed with regard to phytol, squalene, vitamin E, stigmasterol, friedelan-3-ol, friedelin, dodecanoic acid and geranyl acetate in a GC/MSD.

Purification of inulinases by changing the ionic strength of the medium and precipitation with alcohols

ABSTRACT The present study evaluated the purification of inulinase by changing the ionic strength of the medium by addition of NaCl and CaCl2 followed by precipitation with n-propyl alcohol or iso-propyl alcohol. The effects of the concentration of alcohols and the rate of addition of alcohols in the crude extract on the purification yield and purification factor were evaluated. Precipitation caused an activation of enzyme and allowed purification factors up to 2.4-fold for both alcohols. The purification factor was affected positively by the modification of the ionic strength of the medium to 0.5 mol.L-1 NaCl before precipitation with the alcohol (n-propyl or iso-propyl). A purification factor of 4.8-fold and an enzyme yield of 78.1 % could be achieved by the addition of 0.5 mol.L-1 of NaCl to the crude extract, followed by the precipitation with 50 % (v/v) of n-propyl alcohol, added at a flow rate of 19.9 mL/min.