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For the aroma enhancement research of heated cigarettes, it is worth exploring whether tobacco can be pyrolyzed into pyrolysis liquids containing a large number of volatile aroma components. In this study, tobacco pyrolysis liquids were prepared in subcritical/supercritical ethanol, and their applications in the aroma enhancement of heated cigarettes were investigated. The optimal conditions of supercritical liquefaction reactions were determined by optimizing the reaction time, liquid/solid mass ratio and temperature conditions. Moreover, the effect of supercritical liquefaction conditions on volatile aroma components in tobacco pyrolysis liquids was investigated by GC-MS. The results indicated that the reaction temperature had the most significant impact on the tobacco pyrolysis reaction, and higher reaction temperature promoted the pyrolysis conversion of tobacco, resulting in enhanced tobacco conversion and a high content of volatile components in the tobacco pyrolysis liquid. The optimal reaction conditions for the preparation of tobacco pyrolysis liquid were found to be a temperature of 220°C, a liquid/solid mass ratio = 15, and a 2-h reaction time. Meanwhile, the content of ester compounds and nicotine in the tobacco pyrolysis liquid increased significantly with the increase of reaction temperature. Sub/ supercritical ethanol treatment significantly destroyed the surface structure of tobacco, and the degree of tobacco depolymerization increased when temperature rised. The analysis of aroma compounds in the smoke of heated cigarettes indicated that the tobacco pyrolysis liquid could significantly increase the release of aromatic substances and has a significant aroma-enhancing effect. This article proposed and prepared tobacco pyrolysis liquid in subcritical/supercritical ethanol and explored its potential application in the aroma enhancement of heated cigarettes, offering a new route for flavor enhancement technology for this type of product. [ABSTRACT FROM AUTHOR]

Background. Phytosterols are mainly known as a cholesterol-lowering factor, although they form oxidation products during food storage and processing. Moreover, phytosterol oxidation products (POP) can be absorbed and found in human serum, so there is the need to investigate their impact on different kinds of cells. Material and methods. Esters of fatty acids (oleic, linoleic and linolenic) with stigmasterol were synthetized and heated at 180°C, for 1-12 hours. The cytotoxic effect on the leukemic cells of unheated stigmasteryl esters and the mixture of compounds after heating was determined using MTT assays. POP were identified using GC-MS. The total number of POP was analysed by SPE fractionation and GC-FID separation. Dimers, trimers and oligomers in non-polar fraction were determined by gel permeation chromatography with refractive index detection. Results. After heating, stigmasterol oxidation products were formed (up to 1.1 mg/g ester). The heating increased the potency of the compounds to reduce cell population and form POPs and oligomers in a timedependent manner. Conclusion. The cytotoxicity depends on the kind of ester, dose and time. The strongest cytotoxic effect was found after 72 hours of cell treatment. Among the three stigmasteryl esters tested the most cytotoxic effect was caused by stigmasteryl linoleate. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method for ester determination in brandies was developed. • Response surface methodology (RSM) was used for HS-SPME optimization. • A desirability function allowed to optimize multiple metabolite responses. • The method developed was used to characterize the ester profile of sherry brandies. • Differences in the ester profile related to the ageing of brandies were revealed. A specific method for the simultaneous quantification of 28 esters in brandies using headspace solid-phase microextraction and gas-chromatography coupled to mass spectrometry (HS-SPME-GC–MS) was optimised and validated. First, the optimal extraction conditions were determined by using response surface methodology, which were obtained for an extraction temperature of 33 °C for 55 min and a sample dilution of 7.2 % v/v ethanol. Eight deuterated ethyl esters were used as internal standards to provide specificity for the method, which was successfully validated in terms of linearity (R2 > 0.981), repeatability (1 % < RSD < 30 %), reproducibility (1 % < RSD < 18 %), sensitivity (1.1 μg/L < LOQ < 1878 μg/L), accuracy (81 % < recovery < 118 %), and matrix effect. Then, the optimised method was tested on Spanish sherry brandies matured through the traditional dynamic ageing system of Criaderas and Solera , observing an overall decrease in most of the esters during their first years of ageing, although an increase in ethyl esters of branched acids was found. These results confirmed the suitability of the developed method for the determination of esters in brandies and provide the basis for further studies on brandy esters. [ABSTRACT FROM AUTHOR]

A dynamic headspace sorptive extraction (DHS) combined with thermal desorption (TD) and coupled with gas chromatography–mass spectrometry (GC/MS) was developed for the determination of 11 esters which contribute to the fruity aroma in sweet wines. A full factorial (4 factors, 2 level) experiment design was used to optimize the extraction conditions and the results were evaluated by multiple linear regression (MLR) and principal component analysis (PCA). The esters showed optimal extraction using an extraction temperature of 30°C during 20min, and a subsequent purge volume of 300mL and dry volume of 50mL. Afterwards, quantification was achieved using calibration curves constructed for each ester with linear regression equations having correlation coefficients (R 2) ranging from 0.9894 to 0.9981. The proposed method was successfully validated and showed good intermediate precision, repeatability and accuracy values for all the monitored compounds. Finally, the method was applied to quantify esters, with fruity aromatic notes, of sweet white and red wines, elaborated with different winemaking processes. [ABSTRACT FROM AUTHOR]

The irradiation of four Italian white wines with a visible light comparable to that encountered in the market place showed a modification in the amount of aliphatic esters in the wines. Aliphatic esters are responsible for fruity aromas in wines. The first wine studied was the Gewürztraminer, a white wine from Alto Adige (Northern Italy). The amounts of the esters presents in the wine decreased. All the curves follow a pseudo-first-order kinetics. This behaviour can be explained assuming a photooxidation process catalysed by riboflavin. When Arneis Blangè was irradiated, ethyl acetate showed an increase after one day of irradiation; its content then decreased and after five days' irradiation its concentration reached a maximum. Conversely, the concentration of other aliphatic esters decreased after one day's irradiation and then increased progressively to reach a maximum after five days' irradiation. The same behaviour was observed with Pecorino wine. In this case, the concentration of the aliphatic esters decreased until the second day of irradiation but increased after five days' irradiation. In the case of the irradiation of Lighea Zibibbo all the esters showed an increase in concentration after one day of irradiation. The concentration decreased after two days' irradiation, and then increased to reach a maximum after seven days of irradiation. The increase in the amount of esters in some wines and, by contrast, the decrease in the same compounds in Gewürztraminer can be explained by considering that, during the irradiation, the pH of Gewürztraminer did not change, while the pH of Arneis Blangè changed following a curve similar to that showed by the concentration of esters. The pH change can be explained assuming the presence of a photocatalytic process induced by the presence of metals in the wines and influencing the amount of tartaric acid. [ABSTRACT FROM AUTHOR]

In an effort to understand the nature and toxicity of petroleum hydrocarbon degradation metabolites, 2-dimensional gas chromatography linked to a time-of-flight mass spectrometer (GC×GC-TOFMS) was used to conduct nontargeted analysis of the extracts of 61 groundwater samples collected from 10 fuel release sites. An unexpected result was the tentative identification of 197 unique esters. Although esters are known to be part of specific hydrocarbon degradative pathways, they are not commonly considered or evaluated in field studies of petroleum biodegradation. In addition to describing the compounds identified, the present study discusses the role for nontargeted analysis in environmental studies. Overall, the low toxicological profile of the identified esters, along with the limited potential for exposure, renders them unlikely to pose any significant health risk. Environ Toxicol Chem 2015;34:1959-1961. © 2015 The Authors. Published by Wiley Periodicals, Inc., on behalf of SETAC. [ABSTRACT FROM AUTHOR]

• Monitoring MCPD esters and glycidyl esters with HS–SPME–GC–MS instead of liquid injection–GC–MS. • Derivatization, derivatives extraction and desorption with automated equipment. • Employing PBS in the derivatization system for the protection of the SPME fiber. • Screening parameters of SPME fiber with DSD prior to optimization with CCD. • Alkaline hydrolysis is less stable than acidic hydrolysis of MCPD esters. This study aimed to develop a headspace solid-phase microextraction gas chromatography–mass spectrometry (HS–SPME–GC–MS) method for the quantification of 3-monochloropropane-1,2-diol fatty acid esters (3-MCPDEs) and 2-monochloropropane-1,3-diol fatty acid esters (2-MCPDEs), and semi-quantification of glycidyl fatty acid esters (GEs) in edible oils. A central composite design was implemented to optimize the derivatization temperature and extraction time, which were 100 °C and 80 min, respectively. HS–SPME coupled with in-situ derivatization was more straightforward (three steps) and sensitive, with a limit of detection of 16% (3.9 µg/L) and 11% (5.3 µg/L) higher than that of liquid injection method, for 3-MCPD and 2-MCPD, respectively. The recoveries of 3-MCPD and 2-MCPD were in the range of 91.1% to 102.1%, with a relative standard deviation ranging from 0.08 to 9.29%. The validated methodology was successfully applied to oil samples. Further efforts will focus on shortening the extraction time, as 80 min is relatively long. [ABSTRACT FROM AUTHOR]