The use of active PET to package rosé wine: Changes of aromatic profile by chemical evolution and by transfers

Active Polyethylene Terephthalate (PET) bottles containing 1 or 3% of oxygen scavenger (named 1osPET and 3osPET) were used to pack rosé wine. Changes in the aromatic profiles were monitored during 12 months and compared to those of a wine packed in glass bottles. Wine in 1osPET bottles was differentiated from wine in glass or 3osPET bottles by ten aging markers such as cis-dioxane, ethyl pyruvate or furfural. Only trans-1,3-dioxolane allowed to discriminate wine in glass and in 3osPET bottles. Methionol, an oxygen sensitive aroma compound, was preserved in glass and 3osPET bottles but was slightly degraded (15%) in 1osPET bottles. Chemical reactions were the main cause of the aroma compound degradation. Indeed, the total amount of compounds sorbed only reached 160 μg considering the bottles and the joint of cap after 12 months of storage. The use of PET with 3% of oxygen scavenger is adapted to pack wine for at least 12 months

Influence of volatile thiols in the development of blackcurrant aroma in red wine

A strong blackcurrant aroma was recently perceived in some red wines originating from the same appellation. Varietal thiols such as 4-mercapto-4-methyl-2-pentanone (4MMP), 3-(mercapto)hexyl acetate (3MHA) and 3-mercapto-1-hexanol (3MH) are compounds potentially responsible for the development of this aroma. In order to demonstrate the correlation between thiols concentrations in red wines and blackcurrant aroma intensity, a multiple variable analysis was realised with thiols concentrations obtained by chemical analysis and blackcurrant aroma intensities obtained by descriptive sensory analysis. The 4MMP concentration was very well correlated to the blackcurrant aroma, and 3MHA and 3MH present at high concentrations act as enhancers of the perception of this aroma. This correlation was further supported after performing a sensory comparison by classification test. The different factors that could impact on the development of blackcurrant aroma in red wine were discussed

Field—Based Supercritical Fluid Extraction of Hydrocarbons at Industrially Contaminated Sites

Examination of organic pollutants in groundwaters should also consider the source of the pollution, which is often a solid matrix such as soil, landfill waste, or sediment. This premise should be viewed alongside the growing trend towards field-based characterisation of contaminated sites for reasons of speed and cost. Field-based methods for the extraction of organic compounds from solid samples are generally cumbersome, time consuming, or inefficient. This paper describes the development of a field-based supercritical fluid extraction (SFE) system for the recovery of organic contaminants (benzene, toluene, ethylbenzene, and xylene and polynuclear aromatic hydrocarbons) from soils. A simple, compact, and robust SFE system has been constructed and was found to offer the same extraction efficiency as a well-established laboratory SFE system. Extraction optimisation was statistically evaluated using a factorial analysis procedure. Under optimised conditions, the device yielded recovery efficiencies of >70% with RSD values of 4% against the standard EPA Soxhlet method, compared with a mean recovery efficiency of 48% for a commercially available field-extraction kit. The device will next be evaluated with real samples prior to field deployment

Aromatic evolution of wine packed in virgin and recycled PET bottles

The evolution of the aromatic profile of a rose wine packed in glass, virgin and recycled PET bottles was studied. Wine stored in PET and glass bottles was clearly differentiated after 5 months of storage but only by a limited number of compounds. More pronounced decrease of oxygen sensitive compounds such as methionol was observed in PET bottles as well as the apparition of oxidative and ageing aroma compounds such as ethyl pyruvate, furfural or dioxanes in higher concentration. Compared to virgin PET bottles, recycled PET bottles induced slight changes favouring the presence of esters and alcohols. The chemical evolution of wine was the most important phenomenon that explains the loss of flavour rather than the sorption into PET. Because of their moderate oxygen permeability, the use of virgin PET and recycled PET bottles could be adapted for short conservation of wine but detrimental to aromatic quality if long conservation is intended

The reduction of plant sink/source does not systematically improve the metabolic composition of Vitis vinifera white fruit

International audienceThe quality of wine grapes depends on the balance between primary and secondary metabolites. Unlike many perennial crops that accumulate starch in the fruits before ripening, the non-climacteric grapes ripe with no previous carbon reserves. Based on the assumption that fruit carbon sink is limiting metabolite accumulation in grapes, bunch thinning is performed to limit plant Sink/Source (S/S). We studied the effects of severe bunch thinning on the accumulation of primary metabolites and on four families of glycosylated aroma precursors (GAPs) at the arrest of fruit phloem unloading of two white grape Vitis vinifera cvs. At plant level, crop reduction resulted in significant losses of metabolites to be accumulated in the fruits: i.e. up to 72% for sugars, 75% for organic acids and GAPs. Nevertheless, S/S manipulation could not modify the balance between GAPs and primary metabolites or increase the concentration in GAPs in the physiologically ripe grape

Rapid quantification of clove (Syzygium aromaticum) and spearmint (Mentha spicata) essential oils encapsulated in a complex organic matrix using an ATR-FTIR spectroscopic method

Essential oils (EOs) are often encapsulated in various and complex matrices to protect them against potential degradation or to control their release. To achieve an optimum use in food products, their rapid and precise quantification after encapsulation and storage is required. Hence, a rapid ATR-FTIR method was developed and tested with two encapsulated essential oils (EOs): clove (Syzygium aromaticum) and spearmint (Mentha spicata);. Despite, the complexity of the matrix, this method coupled with univariate or multivariate regression models exhibited high potential for global quantification of the two encapsulated EOs. For clove EO, in relation to the major presence of eugenol and eugenol acetate, an analysis based on a unique band (1514 cm(-1)) was sufficient to obtain a good prediction with RMSEP value of 0.0173 g of EO per g of matrix. For spearmint oil which is characterized by numerous terpenoid compound, three bands (799, 885, and 1680-1676 cm(-1)) were suitable for a good prediction with RMSEP value of 0.0133. ATR-FTIR method was compared with a reference gas chromatography FID quantitative method in an EO release experiment and its efficiency was evaluated through modeling by the Avrami equation. Beside time saving, the ATR-FTIR method was also capable of monitoring the EO profile. This method could be easily adapted as a routine analysis in the EOs industry as quality control

Evolution of S-Cysteinylated and S-Glutathionylated Thiol Precursors during Oxidation of Melon B. and Sauvignon blanc Musts

Thiol precursor content in Melon B. and Sauvignon blanc grape juices obtained under vacuum was determined by quantifying cysteinylated and glutathionylated conjugates of 3-mercaptohexan-1-ol (3MH) and 4-methyl-4-mercaptopentan-2-one (4MMP). This characterization allowed the study of thiol precursor evolution during ripening of Sauvignon blanc grapes in several viticultural situations together with grape reaction product (GRP) and the main substrate of polyphenoloxidase, that is, caftaric acid. Concentration of precursors greatly increased during ripening except for the cysteinylated conjugate of 4MMP. Precursor evolution was also monitored during the oxidation of grape juice. Addition of oxygen to a grape juice set off the enzymatic oxidation of hydroxycinnamic acids but did not negatively affect precursor concentrations. Part of the glutathionylated precursor of the 3MH was produced during prefermentative operations (up to 140% in Sauvignon blanc). Consequently, this precursor naturally occurring in grapes was also formed during prefermentative operations. The proportion of biogenetic and prefermentary formation of the glutathionylated precursor of 3MH was different under industrial conditions depending on the grape variety considered. Addition of glutathione and hexenal in grape juices of Melon B. and Sauvignon induced an increase of the production of 3MH and consequently of its acetate in the resulting wines. Residual glutathione in must has to be preserved to enhance the aromatic potential of grapes

A new green insecticide for stored wheat grains: Efficiency against Rhyzopertha dominica and risk assessment

International audienceThis work evidenced the insecticidal activity of encapsulated Mentha spicata essential oil (EO) against Rhyzopertha dominica in presence of stored wheat grain and evaluated the residual EO amount in wheat grains after treatment. EO distribution in the different fractions recovered after grain milling was also determined. The mortality rate against R. dominica reached more than 90% and was dependent on the amount of EO released from the encapsulation matrix. The quantification of the two major compounds of EO, (R)-limonene and (R)-carvone, showed that wheat grains contained different amount depending on the storage conditions. When wheat grains were stored in open jars, the EO residual amount in grains was especially low (1.98 mg/kg) compared to amount in closed jar (51.6 mg/kg). The flour resulting from milling contained lower amount of EO compounds in comparison with the bran fractions. The contact of wheat grains with EO clearly modified the native aromatic profile of the wheat flour as the most represented compounds were those belonging to the EO. In the native flour, ten volatile compounds, mainly alcohols and aldehydes due to oxidation of lipids were identified, which represented only 14% of the aromatic profile when the wheat grains were treated by EO. However, when the storage condition of grains mimics the silos conditions, the level of (R)-carvone, the major component of spearmint EO is found around 3 mg/kg of flour which was far below its currently use in bakery products

Effect of the plant sink/source balance on the metabolic content of the Vitis vinifera L. red grape

International audienceDespite their low concentrations, secondary metabolites are essential to the organoleptic quality of grapevine fruit. Anthocyanins of the fruit skin cells are the principal components of the pigmentation of the red grape. Glycosylated aroma precursors (GAPs), i.e. alcohols, C-13-norisoprenoids, phenols and terpenes determine the aroma potential of the juice and the resulting wine. The regulation of the sink/source (S/S) balance is considered as a one of the more powerful tools to adapt grape composition to technological objectives. In this study, we have manipulated the S/S of Vitis vinifera varieties and quantified the changes on the accumulation of secondary metabolites at the arrest of phloem unloading in the grape. The results demonstrated that the manipulation of the S/S doesn't de-correlate the accumulation of secondary versus primary metabolites. Decreasing S/S drastically limited the accumulation of either primary metabolites (till -70 %), anthocyanins (till -70 %) and GAPs (till -81 %) per plant, with a huge production shortfall of molecules of interest per cultivated area unit

Improved method to quantitatively determine powerful odorant volatile thiols in wine by headspace solid-phase microextraction after derivatization

Correspondance auteur: Rigou P. [email protected] audienceA solid-phase microextraction (SMPE) method coupled to a gas chromatography-mass spectrometry analysis was optimized to analyze the pentafluorobenzyl bromide (PFBBr) derivatives of the volatile thiols 4-methyl-4-mercapto-2-pentanone (4MMP), 3-mercaptohexyl acetate (3MHA) and 3-mercaptohexanol (3MH) in wine. This method used deuterated analogue compounds as internal standards. It allowed us to significantly reduce the matrix effect, resulted in good repeatability for all the compounds (RDS < 9.5% for 4MMP; <6% for 3MH and <4.1% for 3MHA) with limits of detection below their odour thresholds. The method was validated using white, rose and red wines. When applied to analyze different wines, quantities closed to the odour threshold were determined