Effects of copper fungicide spraying on volatile thiols of the varietal aroma of Sauvignon blanc, Cabernet Sauvignon and Merlot wines

In a three-year experiment, the effect of pre-veraison copper sprayings of vines on must composition and some volatile thiols contributing to the varietal aroma of Sauvignon blanc, Cabernet Sauvignon and Merlot wines was studied in comparison with folpet sprayings in the Bordeaux winegrowing region. The readivity of copper residues with thiols, mainly during the alcoholic fermentation, had a dramatic effect on the concentration of 4-mercapto-4-methylpentan-2-one and 3-mercaptohexanol in wines. However, copper sprayings, preferentially on the foliage, did not significantly increase copper residues in must; thiol concentrations in wines were very close to those found in wines obtained from vines sprayed with folpet. Therefore, this mode of spraying can be used to avoid the effects of copper treatment at veraison on the volatile thiols of the wines varietal aroma.

Transcriptomic analysis of the late stages of grapevine (Vitis vinifera cv. Cabernet Sauvignon) berry ripening reveals significant induction of ethylene signaling and flavor pathways in the skin

Background: Grapevine berry, a nonclimacteric fruit, has three developmental stages; the last one is when berrycolor and sugar increase. Flavors derived from terpenoid and fatty acid metabolism develop at the very end of thisripening stage. The transcriptomic response of pulp and skin of Cabernet Sauvignon berries in the late stages ofripening between 22 and 37 \ub0Brix was assessed using whole-genome micorarrays.Results: The transcript abundance of approximately 18,000 genes changed with \ub0Brix and tissue type. There were alarge number of changes in many gene ontology (GO) categories involving metabolism, signaling and abioticstress. GO categories reflecting tissue differences were overrepresented in photosynthesis, isoprenoid metabolismand pigment biosynthesis. Detailed analysis of the interaction of the skin and pulp with \ub0Brix revealed that therewere statistically significantly higher abundances of transcripts changing with \ub0Brix in the skin that were involved inethylene signaling, isoprenoid and fatty acid metabolism. Many transcripts were peaking around known optimalfruit stages for flavor production. The transcript abundance of approximately two-thirds of the AP2/ERF superfamilyof transcription factors changed during these developmental stages. The transcript abundance of a unique clade ofERF6-type transcription factors had the largest changes in the skin and clustered with genes involved in ethylene,senescence, and fruit flavor production including ACC oxidase, terpene synthases, and lipoxygenases. The transcriptabundance of important transcription factors involved in fruit ripening was also higher in the skin.Conclusions: A detailed analysis of the transcriptome dynamics during late stages of ripening of grapevine berriesrevealed that these berries went through massive transcriptional changes in gene ontology categories involvingchemical signaling and metabolism in both the pulp and skin, particularly in the skin. Changes in the transcriptabundance of genes involved in the ethylene signaling pathway of this nonclimacteric fruit were statisticallysignificant in the late stages of ripening when the production of transcripts for important flavor and aroma compoundswere at their highest. Ethylene transcription factors known to play a role in leaf senescence also appear to play a role infruit senescence. Ethylene may play a bigger role than previously thought in this non-climacteric fruit

Identification d'un thiol fortement odorant, le 2-méthyl-3-furanthiol, dans les vins

L'extraction de thiols volatils présents dans les vins a été réalisée avec une technique de distillation sous vide à basse temperature couplée à un piégeage spécifique et réversible de ces composés avec un sel organomercurique, le p-hydroxymercuribenzoate. Aprés décombinaison des thiols en présence d'un excés de cystéine, l'analyse des extraits organiques par chromatographie en phase gazeuse avec divers modes de détection (olfactométrie, photométrie de flamme et spectrométrie de masse) a conduit à l'identification du 2-méthyl-3-furanthiol, un composé fortement odorant (seuil de perception: 0,4-1,0 ng·l-1 dans l'eau), déjà mis en évidence dans le café, la viande cuite et les extraits de levures. Identification of a very odoriferous thiol, 2 methyl-3-furanthiol, in winesVolatile thiols present in wines were extracted with a vacuum distillation technique at low temperature coupled with a specific, reversible capture by an organomercuric salt (p-hydroxymercuribenzoate). After decombination of the thiols with an excess of cystein, the analysis of the organic extracts by gas chromatography with different detection modes (olfactometry, flame photometry and mass spectrometry), led to the identification of 2-methyl-3-furanthiol, a very odoriferous compound (odor threshold. 0.4-1.0 ng.l-1 water). already described in coffee, cooked meat and yeast extracts

Finite Element Modeling and Optimization of Tube-Shaped Ultrasonic Motors

SPIE - The International Society for Optical EngineeringSmart Structures and Materials 2003: Smart Structures and Integrated Systems -- 3 March 2003 through 6 March 2003 -- San Diego, CA -- 61916Recent developments in ultrasonic motor design have demonstrated that small size tube-shaped motors could be fabricated at low cost. Motors with diameters between 15 and 2.5mm have been fabricated and tested. The performance evaluation of these motors is still in progress, but have already shown promising results: the smallest ones exhibit no-load speeds in the range of 70rad/s and blocked torques close to 0.9mN·m. In this paper, we review the operating principle of these devices and several implementation examples. Then, we show how the finite element method (ATILA) can be used, in combination with genetic optimization procedures, to design tube-shaped motors in various dimensions and for different performance objectives. Several design examples are presented and discussed