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

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

Application of differential pH technique to the determination of urea in Italian wines

A method for the quantification of urea in wine, based on measuring the change in pH when urease is added to the sample, is presented and compared to the conventional dual enzyme (urease/glutamate dehydrogenase) approach. The method is linear in the range 0-30 mg·l-1 in red, white and “raisin” wines, and the detection limit (0.3 mg·l-1) is lower than for the usual enzymatic method. The differential pH technique presented here gives accurate quantification of urea in wine, being unaffected by the presence of ammonium. The amounts of urea in 195 still and sparkling commercially available wines with designation of geographic origin from the most renowned Italian grape growing areas were quantified. 17.4 % of samples were over the 3 mg·l-1 level suggested by the International Organisation of Vine and Wine for urease treatment to limit the potential risk for ethyl carbamate formation during wine ageing. Yeast strains EC1118 and SP665 can minimise urea content in wine.

Observation of subdiffusion of a disordered interacting system

We study the transport dynamics of matter-waves in the presence of disorder and nonlinearity. An atomic Bose-Einstein condensate that is localized in a quasiperiodic lattice in the absence of atom-atom interaction shows instead a slow expansion with a subdiffusive behavior when a controlled repulsive interaction is added. The measured features of the subdiffusion are compared to numerical simulations and a heuristic model. The observations confirm the nature of subdiffusion as interaction-assisted hopping between localized states and highlight a role of the spatial correlation of the disorder.Comment: 8 pages, to be published on Physical Review Letter

Changes in the contents of micro- and trace-elements in wine due to winemaking treatments

Forty-four mineral elements quantified by ICP-OES and ICP-MS were measured in wines, (a) after wine fining, at three pH levels with 10 different bentonites (1 g·l-1), (b) after addition of yeast hulls from 2 suppliers to wine (180 and 360 mg·1-1). Bentonite fining resulted in statistically significant increases of the large majority of elements, but in significant lower levels of Cu, K, Rb and Zn. The addition of yeast hulls caused a statistically significant depletion of the contents of Ce, Cu, Fe, La, Sb, U, V and Y.

Distribution of rare earth elements in Vitis vinifera L. 'Chardonnay' berries

The content of 13 rare earth elements (REEs) in the skin, flesh and seeds of 'Chardonnay' berries harvested at technological ripeness in 2 vineyards in Trentino (Italy) with calcareous soils was analysed using inductively coupled plasma mass spectrometry. The total REE content of the berry was 2.1 and 2.7 ug·kg-1 fresh weight (median value, N = 20) respectively in the 2 vineyards, La, Ce and Nd making up about 80 %. Despite the significantly different amounts of REEs in the berries of the 2 vineyards, the percentage content of each element as compared to the total amount of REEs and the percentage distribution in the 3 parts (skin, flesh and seeds) were similar. Overall, 57 % of REEs were localized in the skin, 40 % in the flesh and 3 % in the seeds (median value, N = 40). Most of the elements prevailed in the skin, while there were negligible amounts in the seeds, where the percentage of Eu was around 20 times higher than in the other parts.

Confirming the function of a Final Bronze Age wine processing site in the Nuraghe Genna Maria in Villanovaforru (South Sardinia)

The stone artefact in the hut γ of the NuragheGenna Maria, object of this study, is part of a compound still unpublished today and dated to the Nuragic period. It was found during a 1991 excavation, revealing a situation unchanged since the collapse occurred between the 10th and 9th century B.C., thus preserving the situation at the time of the collapse to this day. The presence of tartaric acid - the marker considered to determinate the presence of wines or products deriving from grapes - has been determined using HPLC-DAD and UHPLC-HQOMS. So the findings under examination, together with the overall evaluation of the archaeological aspects examined, suggests to positively consider the stone artifact as a "laccus" (the latin word for wine presses, still used in the Sardinian language today ) for grape crushing. The internal slope of the floor of the "laccus" allowed the extraction of juice with rapid separation of juice from berry skins. The presence in Sardinia of a large number of "stone wine presses" ("palmenti" in Italian) such as that of the Nuraghe Genna Maria studied in this article, brings a contribution to their dating and confirm the existence of an oenological industry on the island in the Archaic period (9th-10th century B.C.)

The Enzymatic Activity and Molecular Characterization of a Secreted Subtilisin-Like Protease in Microsporum gypseum and Trichophyton vanbreuseghemii

Background: Subtilisin -like proteases are the group of proteases including keratinases found in dermatophytes which de­graded keratin. Determination of the proteases activity of Trichophyton vanbreuseghemii isolates which were obtained from soil and clinical and soil isolates of Microsporum gypseum in Iran and characterization of their genome were aim of present study.Methods: Ezymatic activity was determined by use of chromogenic substrates. The genes, which coded subtilisin-like pro­teases in above-mentioned dermatophytes, was identified and amplified by using specific primers in PCR. Results: The highest yield of enzyme production was observed in only one isolate of T. vanbreuseghemii Ir-84 whereas low enzyme activity was observed in M. gypseum isolates. Homology study of obtained nucleotide as well as amino acid sequences indicated different rates of homology with other subtilisin-like proteases genes in other pathogenic dermato­phytes. Conclusion: Intra-strain differences were observed in production of serine proteinases and molecular characterization of genes encoding such enzymes could be of great interest for studies on pathogenicity and other purposes

Rapid quantification of 4-ethylphenol in wine using high-performance liquid chromatography with a fluorimetric detector

A rapid method was established for quantifying 4-ethylphenol in wine using HPLC with a detector usually present in wine laboratories. It does not require sample preparation and carries out chromatographic separation in less than 5 min, making control of wine production processes easier. The method is linear up to 2000 μg·l-1 with RSD < 3 % over 20 μg·L-1 and gives a detection limit of 4.0 μg·L-1. It was validated in comparison with the HPLC-coulometric array detector, giving comparable results. Its application to the analysis of 720 DOC and table Italian red wines revealed that the 45 % of them had contents of 4-ethylphenol potentially affecting sensory perception of the aroma.