1,091 research outputs found

    Status of yeast assimilable nitrogen in Italian grape musts and effects of variety, ripening and vintage

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    The content of promptly assimilable nitrogen by yeast (PAN) was analysed in 586 juices from technologically ripe grapes collected in several Italian regions. A spectrophotometric method within the reach of each wine laboratory was used, adapting a previous method of the American Society of Brewing Chemists used for wort to grape juices. 58.3 % of the samples were below the classic deficiency threshold of 140 mg·l-1. Among varieties and vintages there were significant differences. An overall trend of PAN to slightly decrease with ripening was observed. The variability of the PAN content of numerous samples harvested in a vineyard to check ripeness seems to be larger than that for sugars and total acidity

    Assessment of the susceptibility of roads to flooding based on geographical information – test in a flash flood prone area (the Gard region, France)

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    International audienceIn flash flood prone areas, roads are often the first assets affected by inundations which make rescue operations difficult and represent a major threat to lives: almost half of the victims are car passengers trapped by floods. In the past years, the Gard region (France) road management services have realized an extensive inventory of the known road sub- mersions that occurred during the last 40 years. This inven- tory provided an unique opportunity to analyse the causes of road flooding in an area frequently affected by severe flash floods. It will be used to develop a road submersion suscep- tibility rating method, representing the first element of a road warning system.This paper presents the results of the analysis of this data set. A companion paper will show how the proposed road susceptibility rating method can be combined with dis- tributed rainfall-runoff simulations to provide accurate road submersion risk maps.The very low correlation between the various possible ex- planatory factors and the susceptibility to flooding measured by the number of past observed submersions implied the use of particular statistical analysis methods based on the general principals of the discriminant analysis.The analysis led to the definition of four susceptibility classes for river crossing road sections. Validation tests con- firmed that this classification is robust, at least in the con- sidered area. One major outcome of the analysis is that the susceptibility to flooding is rather linked to the location of the road sections than to the size of the river crossing structure (bridge or culvert)

    Aroma components of Galician Albariño, Loureira and Godello wines

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    Wines of the three most interesting Galician white grape varieties have been deeply analyzed for three aroma categories: the volatile compounds, except for monoterpenols, the monoterpenols and the bound forms. Many compounds showed significant differences between the wine groups, as proved by Tukey's test, e.g. for methanol, trans and cis 3-hexen-1-ols and relevant ratio, benzaldehyde and 4-vinylguaiacol in the first category, and for the most part of compounds of the other two categories. Loureira and most Albariño wines contain linalool and ho-trienol at a level of sensorial contribution. The relevant average terpene profiles show many similarities, especially for Albariño and particularly if considering the contents and relevant ratios of furan and pyran linalool oxide isomers, of ho-diendiols I and II and of geraniol. On the other hand differences could be stated for some compounds, mostly under the bound forms. Godello wines, with the poorest content of monoterpenols under both forms, are principally characterized by a marked level of bound benzaldehyde, with contemporary presence of a considerable average level of the free form. PCA data treatments on both monoterpenols and aglycons from the bound forms, showed a good separation among the groups as well a good homogeneity and varietal correspondence of the wines

    Structural identification and presence of some p-menth-1-enediols in grape products

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    The present work aims at clearing the structure of some p-menthenediols, which are already known to be present in musts and wines as glycosides, referred to as isomers 1, 2 and 3. Isomers 2 and 3 correspond to cis-p-menth-1-ene-6,8-diol and p-menth-1-ene-7,8-diol; isomer 1, which is only found in traces, is probably identical with trans- p-menth-1-ene-6,8-diol. Their concentration is reported for both free and bound forms in musts from some varieties and compared with the alpha-terpineol and 2-exo-hydroxy-1,8-cineole concentrations. In general, the free forms were scarcely present; among the bound forms p-menth-1-ene-7,8-diol first and then cis-p-menth-1-ene-6,8-diol prevailed. Besides improvement of varietal classification, the compounds identified give evidence of allylic hydroxylase activity in grape berries
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