Wpływ wolnych glukozydów steroli na parametry niskotemperaturowe paliw i biopaliw

The depletion of primary energy sources and the increase in greenhouse gas emissions to the atmosphere necessitate taking action to seek alternative sources, including renewable energy sources. In March 2011, the European Commission issued a new White Paper – "Roadmap to a Single European Transport Area – Towards a competitive and resource efficient transport system" [White Paper; 2011]. The White Paper presents a vision of a competitive and sustainable transport system, ensuring its further growth and mobility while achieving the goal of reducing greenhouse gas emissions by 60% in 2050. The directions of development of motor fuels are mainly determined by the undesirable climate changes that negatively affect the environment, as well as by the constant development of engine designs in order to meet the increasing requirements of environmentalists and users. The modern world has realized that it is facing a serious environmental threat caused by CO2 emissions largely from car transport. Widely understood environmental protection, and also climate protection, requires the use of more eco-friendly engine fuels, which is reflected by European Union Directives and, consequently, in national legislation. A further increase in the share of biofuels and biocomponents in fuels intended for transport is expected, and these will not only be first generation fuels derived from vegetable oil transesterification (VOE) such as the currently commonly used fatty acid methyl esters (FAME) or fuels derived from the hydrotreatment of vegetable oils and animal fats (HVO), but also liquid fuels produced from biomass and bio-waste through thermochemical conversion. Low-temperature properties, and also the presence of biocomponents (FAME) in diesel fuel, which is the source of deposits in the engine and in its fuel system, causing many operational problems, are one of the important quality parameters of fuels intended for supplying diesel engines (ZS). FAME from rapeseed oil, widely used in the European Union as a biofuel for compression-ignition engines, has not, until recently, been suspected of affecting the performance parameters of the final product by the trace substances they contain, such as free sterol glucosides. In 2011, Polish fuel bases signaled the problem of a large amount of greasy deposits in tanks with a mixture of 5% (V/V) FAME in fuel for supplying diesel engines. Large amounts of free sterol glucosides were detected in these sediments using the research methodology developed by the author of this work. In the subject mixtures of commercial fuels and reference materials, relationships between low-temperature parameters such as cloud point CP, cold CFPP filter block temperature, CSFT cold filtration time on the one hand, and the content of FAME trace components from rapeseed oil: free sterol glucosides (FSG) and saturated monoacylglycerols (SMG) on the other hand, were determined. Keywords: low-temperature parameters, biodiesel, diesel fuel, free sterol glucosides

Gas Chromatographic Determination and Method Validation of Stigmasterol, Β-Sitosterol, Campesterol and Brassicasterol Contents of Turkish Cottonseed Oil Samples

Plant sterols are important agricultural products for human health and consequently, for nutrition industries. In the present study, free sterol contents of crude Turkish cottonseed oil samples have been determined in a single analytical run by using a solid phase extraction step prior to the detection with a gas chromatography coupled with a flame ionization detector. Free hydroxyl groups of Stigmasterol, β-Sitosterol, Campesterol and Brassicasterol were derivatized by using N-methyl-N-trimethylsilyl trifluoroacetamide to enhance their volatility and, sterol content of the samples were, then, separated from their matrix by using a octadecylsilane cartridge. The eluates were injected into the gas chromatographic system and satisfactory recovery ratios were obtained. After having validated the method, it was applied into the analysis for cottonseed oil samples for their free sterol levels.

Neutral lipids in cercariae, encysted metacercariae, and rediae of Echinostoma caproni

High performance thin-layer chromatography (HPTLC) was used to analyse the neutral lipids in the rediae, cercariae, and encysted metacercariae of Echinostoma caproni from Biomphalaria glabrata snails. Visual observations of the chromatograms showed that the most abundant lipid fraction in all stages was free sterol. Quantification of the free sterol revealed mean weights of 2.7 ± 0.64 ng per redia, 0.53 ± 0.023 ng per cercaria, and 0.081 ± 0.0098 ng per encysted metacercaria. Oil Red O staining of the larval stages confirmed the presence of lipids within the rediae and cercariae but did not show lipids in the encysted metacercariae. The dimunition in neutral lipids from the cercarial to the encysted metacercarial stage does not support a previous observation that fat increases in successive phases of the digenean life cycle.

Canopy Position and Heat Treatments Influence Gamma-irradiation-induced Changes in Phenylpropanoid Metabolism in Grapefruit

Irradiation is being evaluated as a quarantine treatment of grapefruit (Citrus paradisi Macf. `Marsh'), but it can cause damage to the fruit. Research was conducted to determine if preirradiation heat treatments would improve fruit tolerance to irradiation as they improve tolerance to low temperature injury and to determine if canopy position influenced fruit tolerance to irradiation. Initially, grapefruit were irradiated at 0 or 2.0 kGy at a dose rate of 0.14 kGy·min-1 and selected biochemical changes were monitored over time. There was a marked increase in phenylalanine ammonia-lyase (PAL) activity following irradiation. Maximum activity (≈18-fold increase) was attained 24 hours after irradiation. Subsequently, grapefruit were harvested from interior and exterior canopy positions and irradiated at 0 or 1.0 kGy at a dose rate of 0.15 kGy·min-1 before storage for 4 weeks at 10 °C. Following storage, pitting of flavedo was the most evident condition defect noted as a result of irradiation. Pitting was observed on 27% and 15% of irradiated exterior and interior canopy fruit, respectively, whereas there was no pitting on nonirradiated fruit. Heat treatment before irradiation decreased susceptibility of fruit to damage. Pitting was 26%, 19%, and 17% when fruit were held 2 hours at 20 (ambient), 38 or 42 °C, respectively. Irradiation-induced PAL activity was reduced by temperature conditioning at 38 or 42 °C. Exterior canopy fruit flavedo contained higher levels of total phenols, including flavanols and coumarins compared with interior canopy fruit. Deposition of lignin was not related to canopy position. Neither irradiation nor heat treatment had an effect on total phenols or lignin deposition. Generally, cholesterol, campesterol, stigmasterol, β-sitosterol, and isofucosterol were found to be higher in four steryl lipid fractions in exterior canopy fruit compared with interior canopy fruit. Irradiation increased campesterol in the free sterol and steryl glycoside fractions and decreased isofucosterol in the free sterol fraction. Heat treatments had no effect on individual sterol levels. It seems that irradiation causes a stress condition in the fruit, which leads to pitting of peel tissue. Heat treatment before irradiation reduced damaging effects of irradiation.

138 LIPID CHANGES IN TOMATO FRUIT MICROSOMAL MEMBRANES DURING RIPENING

A previous study of lipids from pericarp tissue of tomato fruit ranging from mature-green to red-ripe showed a large increase in total sterols accompanied by dramatic changes in sterol composition and conjugation with ripening. This study was conducted to determine whether similar changes occur in microsomal membranes derived from tomato fruit pericarp. Acylated steryl glycoside (ASG), the predominant steryl lipid, declined during ripening, with increases in steryl glycoside (SG) and free sterol (FS). Only minor changes in fatty acid composition were associated with the drop in ASG. The stigmasterol:sitosterol ratio increased throughout ripening, but much more in Fs than in SG or ASG. The ratio of FS to phospholipid (PL) increased with ripening. However, FS was never greater than 10 percent of the total membrane sterol (TMS), and TMS:PL actually declined over the middle stages of ripening. It is not known why tomato tissues maintain such high levels of ASG and SG, but sterol conjugation is thought to regulate the physical properties of cell membranes.