The effect of ultrasound on lipase-catalyzed hydrolysis of soy oil in solvent-free system.

Comparative studies of lipase-catalyzed hydrolysis of soy oil in solvent-free system were carried out in shaking bath and in ultrasonic bath. A suitable ultrasonic power of 1.64 W cm(-2) was determined to guarantee satisfactory hydrolysis extent and lipase activity. The influence of temperature, pH, enzyme concentration and water/oil ratio was investigated subsequently. Compared with that in shaking bath, optimum temperature and inactivation temperature of lipase in ultrasonic bath were about 5-10 degrees C higher, while pH effect in ultrasonic bath was similar; ultrasound also led to a smooth increase of reaction rate at relatively higher enzyme loading and less use of water to saturate hydrolysis substrate. In optimum conditions, the overall hydrolysis reaction rate in the ultrasonic bath process was above 2-fold than that in the shaking bath process.

Influence of bleaching by ultrasound on fatty acids and minor compounds of olive oil. Qualitative and quantitative analysis of volatile compounds (by SPME coupled to GC/MS).

The effects of bleaching using high power ultrasound (20 kHz) on the quality of olive oil were considered in this study, in order to verify the modifications that can occur in fatty acid composition and minor compounds. During the treatment of olive oil under ultrasonic waves, a rancid odour has been detected. Treated olive oils show no significant changes in their chemical composition but the presence of some volatile compounds, due to ultrasonic treatment. Some off-flavour compounds (hexanal, hept-2-enal and 2(E),4(E)-decadienal) resulting from the sonodegradation of olive oil have been identified. A wide variety of analytical techniques (GLC, HPLC and GC/MS) were used to follow the quality of bleached olive oils with ultrasonic waves by the determination of the amounts of certain minor compounds such as sterols and tocopherols. Steradienes, resulting from the dehydration of sterols, were detected with small quantities especially in severe conditions of sonication. Solid phase micro-extraction (SPME) coupled to gas chromatography was known to be a sensitive technique to follow changes in the oxidative state of vegetable oils by measuring the amount of volatile materials produced during the refining process.

Effects of whole body exposure to extremely low frequency electromagnetic fields (ELF-EMF) on serum and liver lipid levels, in the rat.

BACKGROUND: [corrected] The effects of extremely low-frequency electromagnetic fields (ELF-EMF) on the blood serum and liver lipid concentrations of male Wistar rats were assessed. METHODS: Animals were exposed to a single stimulation (2 h) of ELF-EMF (60 Hz, 2.4 mT) or sham-stimulated and thereafter sacrificed at different times (24, 48 or 96 h after beginning the exposure). RESULTS: Blood lipids showed, at 48 h stimulated animals, a significant increase of cholesterol associated to high density lipoproteins (HDL-C) than those observed at any other studied time. Free fatty acid serum presented at 24 h significant increases in comparison with control group. The other serum lipids, triacylglycerols and total cholesterol did not show differences between groups, at any time evaluated. No statistical differences were shown on total lipids of the liver but total cholesterol was elevated at 24 h with a significant decrease at 96 h (p = 0.026). The ELF-EMF stimulation increased the liver content of lipoperoxides at 24 h. CONCLUSION: Single exposures to ELF-EMF increases the serum values of HDL-C, the liver content of lipoperoxides and decreases total cholesterol of the liver. The mechanisms for the effects of ELF-EMF on lipid metabolism are not well understand yet, but could be associated to the nitric oxide synthase EMF-stimulation.

Metabolic changes after non-lethal x-irradiation of rats. II. Serum and tissue lipids.

Male rats of the Wistar strain were subjected to whole-body X-irradiation with 2.39 Gy (250 R) and after irradiation they were pair-fed with the sham-irradiated control group. One, 6 and 24 h, 2, 3, 7, 14, 21, 28, and 38 days after exposure the animals were sacrificed and examined for serum and some tissue lipids. In the first hours an increase in lipolysis in the white adipose tissue and accumulation of NEFA and TG in the liver predominated; PL level increased in serum and liver and decreased in bone marrow and thymus. The later phase was characterized by hypertriacylglycerolaemia and a transient hypercholesterolaemia; accumulation of TG in bone marrow was the most important change, however. Changes in the lipid composition of the serum and tissues, except for an increase in TG level in thymus, returned to normal levels at the end of the observation period. Pair-feeding provided an equivalent nutritional situation in irradiated and sham-irradiated animals and thus eliminated the non-specific changes caused by different levels of food intake in both groups of animals, especially in the initial period. A sufficiently long observation period is necessary for estimating the kinetics of metabolic changes in rats exposed to non-lethal doses of X-irradiation.

Changes in whole-body metabolic parameters associated with radiation.

Continuous irradiation of experimental animals is an appropriate model for the research in space radiobiology. The onset and recovery of radiation injury can be estimated on the basis of the concentration/content of glycogen in liver, the phospholipid content in thymus and other radiosensitive organs and the triacylglycerol concentration in bone marrow. Further, the picture of the metabolism in irradiated organism may be completed by the analysis of serum glucocorticoid and thyroid hormone levels.

An ultrasonic-accelerated oxidation method for determining the oxidative stability of biodiesel.

Biodiesel is considered an alternative energy because it is produced from fats and vegetable oils by means of transesterification. Furthermore, it consists of fatty acid alkyl esters (FAAS) which have a great influence on biodiesel fuel properties and in the storage lifetime of biodiesel itself. The biodiesel storage stability is directly related to the oxidative stability parameter (Induction Time - IT) which is determined by means of the Rancimat® method. This method uses condutimetric monitoring and induces the degradation of FAAS by heating the sample at a constant temperature. The European Committee for Standardization established a standard (EN 14214) to determine the oxidative stability of biodiesel, which requires it to reach a minimum induction period of 6h as tested by Rancimat® method at 110°C. In this research, we aimed at developing a fast and simple alternative method to determine the induction time (IT) based on the FAAS ultrasonic-accelerated oxidation. The sonodegradation of biodiesel samples was induced by means of an ultrasonic homogenizer fitted with an immersible horn at 480Watts of power and 20 duty cycles. The UV-Vis spectrometry was used to monitor the FAAS sonodegradation by measuring the absorbance at 270nm every 2. Biodiesel samples from different feedstock were studied in this work. In all cases, IT was established as the inflection point of the absorbance versus time curve. The induction time values of all biodiesel samples determined using the proposed method was in accordance with those measured through the Rancimat® reference method by showing a R(2)=0.998.

Microwave-accelerated energy-efficient esterification of free fatty acid with a heterogeneous catalyst.

This paper shows energy-efficiency of microwave-accelerated esterification of free fatty acid with a heterogeneous catalyst by net microwave power measurement. In the reaction condition of 5 wt% sulfated zirconia and 1:20 M ratio of oil to methanol at 60°C and atmospheric pressure, more than 90% conversion of the esterification was achieved in 20 min by microwave heating, while it took about 130 min by conventional heating. Electric energy consumption for the microwave heating in this accelerated esterification was only 67% of estimated minimum heat energy demand because of significantly reduced reaction time.

[Endogenous phospholipase hydrolysis in radiation injury of animals]. / Endogennyi fosfolipaznyi gidroliz pri luchevom porazhenii zhivotnykh.

A study was made of the free fatty acid (FFA) content of homogenates of brain, thymus, liver, kidneys, erythrocytes, small intestine mucosa, and spleen of X-irradiated (7.76 Gy) rats. The increased FFA content was exhibited by all the organs under study. The increase was maximum in the thymus. Calcium ions were shown to play a defined role in the radiation enhancement of endogenous phospholipase hydrolysis.

[Effect of ionizing radiation on the functional state of snail neurons. Phospholipid composition and levels of free fatty acids]. / Deistvie ioniziruiushchei radiatsii na funktsional'noe sostoianie neironov vinogradnoi ulitki. Fosfolipidnyi sostav i uroven' svobodnykh zhirnykh kislot.

A study was made of the effect of ionizing radiation on the phospholipid composition and the level of free fatty acids in nervous ganglia of edible snails (Helix pomatia). Ionizing radiation was shown to decrease the total content of phospholipids and to change certain fractions and accumulation of lysoforms. The increase in the free fatty acid content indicated an activation of endogenous phospholipase hydrolysis. Model experiments on treatment of nervous ganglia with phospholipase A2 demonstrated a similarity of radiation-induced changes in the phospholipid content.

[Effect of tocopherol on free fatty acid levels in the erythrocyte membranes of rats undergoing x-ray irradiation]. / Vliianie tokoferola na uroven' svobodnykh zhirnykh kislot v membranakh éritrotsitov krys pri rentgenovskom obluchenii.

The effect of tocopherol on the level of free fatty acids was quantitatively estimated at early times after irradiation. Tocopherol was shown to retard the growth of the free fatty acid level in rat erythrocyte membranes during the first 24 h following irradiation.

[The content of phospholipids and free fatty acids in the sarcoplasmic reticulum membranes in the early stage of an x-ray radiation lesion]. / Soderzhanie fosfolipidov i svobodnykh zhirnykh kislot v membrannakh sarkoplazmaticheskogo retikuluma na rannem étape porazheniia rentgenovskim izlucheniem.

One and 24 h following single X-irradiation (0.21 C/kg) of rabbit hind leg the content of free fatty acids and phospholipid lysoforms increased in the sarcoplasmic reticulum (SR) membrane of skeletal muscles. The results obtained are important in estimating the mechanisms of action of ionizing radiation on the structural and functional properties of SR.

[The biological effects in animals in relation to the accident at the Chernobyl Atomic Electric Power Station. 7. The content of lipid peroxidation products and free fatty acids and the catalase activity in a number of organs and tissues of rats]. / Biologicheskie éffekty u zhivotnykh v sviazi s avariei na Chernobyl'skoi AES. Soobshchenie 7. Soderzhanie nekotorykh produktov perekisnogo okisleniia lipidov, svobodnykh zhirnykh kislot i aktivnost' katalazy v riade organov i tkanei krys.

The content of malonic dialdehyde, dienic conjugates and free fatty acids, and catalase activity were determined in some organs and tissues of chronically irradiated rats. Certain regularities were found in lipid metabolism changes. The MIGI-K preparation was shown to normalize some indices under study.

[Effects of ubiquinone-9 on lipids of nuclei and chromatin of the rat liver under continuous irradiation]. / Vliianie ubikhinona-9 na lipidy iader i khromatina pecheni krys v usloviiakh khronicheskogo oblucheniia.

The influence of continuous gamma irradiation on the lipids of nuclei and chromatin of rat liver at a dose-rate of 0,129 Gy/day for 155 days (a total dose of 20 Gy) and by feeding of ubiquinone-9 has been studied. The amount of phosphatidylcholine with phosphatidylserine and phosphatidyl-ethanolamine in liver nuclei of irradiated rats was found to increase. Ubiquinone-9 had a normalizing effect. A decrease of cardiolipin was observed in the liver chromatin of irradiated rats. The amount of free fatty acids had a tendency to decrease in homogenate, nuclei and liver chromatin of irradiated rats. Ubiquinone was found to increase the amount of free fatty acids up to the control level. The amount of cholesterol in nuclei was increased after irradiation and that in chromatin tended to rise. Ubiquinone-9 significantly decreased the amount of cholesterol in nuclei and chromatin of irradiated rats.