Effect of foliar urea fertilisation on volatile compounds in Tempranillo wine.

BACKGROUND: The impact of fertilisation with three doses of foliar urea (0, 2 and 4 kg N ha(-1)) on the concentration of volatile compounds in Tempranillo wine was studied. RESULTS: The total concentration of alcohols decreased with the application of urea. The concentrations of ethyl hexanoate, ethyl octanoate and ethyl decanoate were highest in the wine resulting from the 4 kg N ha(-1) urea treatment. Fatty acids showed different individual responses to the application of urea. Sensory analysis indicated that the wines from urea-treated grapevines had higher aroma intensity and a more fruity character than the control wine. CONCLUSION: It may be concluded that foliar urea fertilisation shows itself to be efficient in small doses as a complement to soil fertilisation to improve wine aroma.

A species-specific method for detecting pathogenic Streptomyces species from soil and potato tubers in Argentina.

Potato common scab is caused by several soil-inhabiting pathogenic Streptomyces species. In the present study, a species-specific PCR method was used to detect Streptomyces species in potato tuber lesions and soils. Total genomic DNA from soil samples from six locations and tuber samples from four potato cultivars (Spunta, Shepody, Innovator and Russet Burbank) were assessed. Streptomyces scabies, Streptomyces acidiscabies, and Streptomyces turgidiscabies were detected in soybean, tobacco and potato soils and in all potato varieties except Russet Burbank. The phylogenetic analysis of the sequences obtained confirmed the identification. The method proposed proved to be time-saving and cost effective for the rapid detection of Streptomyces species. This is the first report of the detection of S. acidiscabies and S. turgidiscabies in soils and potato tubers from Argentina.

Foliar application of urea to Tempranillo vines increased the amino acid concentration of the must.

The aim of this study was to investigate the impact of fertilisation with foliar urea of Vitis vinifera var. Tempranillo on the concentration of amino acids in must and on their evolution during the final stage of grape ripening. Foliar urea fertilisation increased the concentration of amino nitrogen, ammonium nitrogen and yeast assimilable nitrogen (YAN) in Tempranillo must. In addition, fertilisation with foliar urea produced an increase in the concentration of many amino acids in the must. This increase was especially noticeable in the case of the most important amino acids for yeast metabolism throughout the alcoholic fermentation (arginine, glutamic acid, aspartic acid, histidine, serine and lysine). After comparing the results of this study with other ones, we may state that: in order to increase the amino acid concentration in must, it is important to apply the urea several times instead of making just one single application. Moreover, it is important to use a preparation of urea without biuret, which is a phytotoxic carbamyl urea formed as a condensation product arising from urea thermal decomposition.

Characterization of Fusarium graminearum isolates recovered from wheat samples from Argentina by Fourier transform infrared spectroscopy: Phenotypic diversity and detection of specific markers of aggressiveness.

Fusarium graminearum is the primary causal agent of Fusarium head blight of wheat in Argentina. This disease affects crop yields and grain quality also reducing the wheat end-use, and causing mycotoxin contamination. The aim of this work was to analyze the phenotypic characteristics associated with phenotypic diversity and aggressiveness of 34 F. graminearum sensu stricto isolates recovered from Argentinean fields in the 2008 growing season using the Fourier Transform Infrared (FTIR) dried film technology. We applied this technique also to search for spectral specific markers associated with aggressiveness. The combination of FTIR technology with hierarchical cluster analysis allowed us to determine that this population constitutes a highly diverse and heterogeneous group of fungi with significant phenotypic variance. Still, when the spectral features of a set of these isolates were compared against their aggressiveness, as measured by disease severity, thousand grains weight, and relative yield reduction, we found that the more aggressive isolates were richer in lipid content. Therefore, we could define several spectroscopic markers (>CH stretching modes in the 3000-2800 window, >CO and CO vibrational modes of esters at 1765-1707cm-1 and 1474-900cm-1, respectively), mostly assigned to lipid content that could be associated with F. graminearum aggressiveness. All together, by the application of FTIR techniques and simple multivariate analyses, it was possible to gain significant insights into the phenotypic characterization of F. graminearum local isolates, and to establish the existence of a direct relationship between lipid content and fungal aggressiveness. Considering that lipids have a major role as mediators in the interaction between plants and fungi our results could represent an attractive outcome in the study of Fusarium pathogenesis.

Effects of reduced levels of sulfite in wine production using mixtures with lysozyme and dimethyl dicarbonate on levels of volatile and biogenic amines.

Sulphur dioxide (SO2) is an important preservative for wine, but its presence in foods can cause allergies and this has given impetus to the research for alternatives. The aim of this study was to reduce levels of sulfite in wine production using mixtures with lysozyme and dimethyl dicarbonate and examine the influence on levels of volatile and biogenic amines. To do so, vinifications were carried out using lysozyme, dimethyl dicarbonate (DMDC) and mixtures of these with SO2 in different concentrations (25 and 50 mg l-1). Results were compared with a control vinification with only SO2 (50 mg l-1). Mixing low concentrations of SO2 with lysozyme and DMDC reduced the concentration of biogenic amines (histamine, tyramine, putrescine, cadaverine, phenylethylamine + spermidine and spermine). In general, the total concentration of volatile amines (dimethylamine, isopropylamine, isobutylamine, pyrrolidine, ethylamine, diethylamine, amylamine and hexylamine) was higher in the sample fermented only with SO2. The concentrations of amines with secondary amino groups (dimethylamine, diethylamine, pyrrolidine) were higher in the sample only fermented with SO2 than those fermented with DMDC and lysozyme or with a mixture of preservatives. When SO2 was the only preservative in wine, total amine concentration (biogenic and volatile amines) was higher than for the rest of the treatments. Lysozyme by itself, and lysozyme mixed with SO2, both reduced the formation of biogenic amines but given the antioxidant activity of SO2 the use of the preservative mixture seems more advisable.

Improvement of wine aromatic quality using mixtures of lysozyme and dimethyl dicarbonate, with low SO2 concentration.

The use of sulphur dioxide (SO2) in the treatment of foodstuffs presents some problems as it could lead to pseudo-allergies in some people. The aim of this research work was to study the addition of different preservative mixtures and their influence on the concentration of volatile compounds and sensorial quality in wine. To do so, vinifications were carried out using Garnacha must to which lysozyme, dimethyl dicarbonate (DMDC) and mixtures of these with SO2 were added at different doses (25 and 50 mg l(-1)). The results were compared with a control sample to which only SO2 had been added (50 mg l(-1)). In general, mixtures of SO2 with lysozyme and DMDC favoured the formation of volatile compounds in the wines. Wines obtained from the mixtures of lysozyme and DMDC with 25 mg l(-1) of SO2 had better sensorial quality than the wines obtained with 50 mg l(-1) as the only preservative used.

Sorption of 4-ethylguaiacol and 4-ethylphenol on yeast cell walls, using a synthetic wine.

4-Ethylphenol (4-EP) and 4-ethylguaiacol (4-EG) are the identified volatile phenolic compounds associated with off-odour in wine. The aim of this work was to investigate the kinetics and thermodynamics of sorption of 4-EG and 4-EP by yeast cell walls, using a synthetic wine. Results showed that the sorption capacity by yeast cell walls for 4-EG was greater than that for 4-EP and that the kinetics of 4-EG were quicker, although the unions were weaker than in the case of 4-EP. The retention of these compounds was by means of specific chemical sorption. The process of sorption of these compounds to the yeast walls could be due to their binding to the residual lipids, as well as to interaction of 4-EP and 4-EG (positively charged compounds), with the functional groups of the mannoproteins and the free amino acids of the surface of the cell walls.

SO(2) protects the amino nitrogen metabolism of Saccharomyces cerevisiae under thermal stress.

Thermal stress conditions during alcoholic fermentation modify yeasts' plasma membrane since they become more hyperfluid, which results in a loss of bilayer integrity. In this study, the influence of elevated temperatures on nitrogen metabolism of a Saccharomyces cerevisiae strain was studied, as well as the effect of different concentrations of SO(2) on nitrogen metabolism under thermal stress conditions. The results obtained revealed that amino nitrogen consumption was lower in the fermentation sample subjected to thermal stress than in the control, and differences in amino acid consumption preferences were also detected, especially at the beginning of the fermentation. Under thermal stress conditions, among the three doses of SO(2) studied (0, 35, 70 mg l(-1) SO(2) ), the highest dose was observed to favour amino acid utilization during the fermentative process, whereas sugar consumption presented higher rates at medium doses.

Circulating 92-kilodalton matrix metalloproteinase (MMP-9) activity is enhanced in the euglobulin plasma fraction of head and neck squamous cell carcinoma.

BACKGROUND: Cancer lethality is usually the result of local invasion and metastasis of neoplastic cells from the primary tumor. Because of their ability to degrade extracellular matrix components (EMC), matrix metalloproteinases (MMPs) have been implicated in the breakdown of basement membranes and underlying stroma, thereby facilitating tumor growth and invasion. METHODS: The authors quantitated, by gelatin zymography and densitometric analysis, MMP activity in the euglobulin plasma fraction of 50 healthy controls and 91 head and neck squamous cell carcinoma (HNSCC) patients (51 from the larynx and 40 from the oropharynx). RESULTS: The median value for 92-kilodalton (kD) MMP (MMP-9) activity was increased significantly in laryngeal (Md 2.1 arbitrary units (AU)/mL plasma; range, 0.2-6.4) and oropharyngeal patients (Md 2.08 AU/mL; range, 0.0-5.0) with respect to the controls (Md 0.48 AU/mL; range, 0.0-1.8). Both groups of cancer patients showed a similar behavior. Multivariate analysis indicated that circulating 92-kD MMP activity was not predicted by the clinical-pathologic parameters such as tumor stage, histologic grade, and metastatic lymph nodes. There was no association between high levels of MMP-9 activity and either cigarette smoking or alcohol consumption, major risk factors for developing HNSCC. CONCLUSIONS: The authors found a significant increase of MMP-9 plasma activity both in laryngeal and oropharyngeal squamous cell carcinoma patients as compared with healthy controls. Further studies are necessary to establish its usefulness in the clinical management of these patients.

A species-specific method for detecting pathogenic Streptomyces species from soil and potato tubers in Argentina / A species-specific method for detecting pathogenic Streptomyces species from soil and potato tubers in Argentina.

Potato common scab is caused by several soil-inhabiting pathogenic Streptomyces species. In the present study, a species-specific PCR method was used to detect Streptomyces species in potato tuber lesions and soils. Total genomic DNA from soil samples from six locations and tuber samples from four potato cultivars (Spunta, Shepody, Innovator and Russet Burbank) were assessed. Streptomyces scabies, Streptomyces acidiscabies, and Streptomyces turgidiscabies were detected in soybean, tobacco and potato soils and in all potato varieties except Russet Burbank. The phylogenetic analysis of the sequences obtained confirmed the identification. The method proposed proved to be time-saving and cost effective for the rapid detection of Streptomyces species. This is the first report of the detection of S. acidiscabies and S. turgidiscabies in soils and potato tubers from Argentina.