Lara Tat

University of Udine, Udine, Friuli Venezia Giulia, Italy

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Publications (14)22.81 Total impact

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    ABSTRACT: Edible films may act as carriers of active molecules, such as flavours. This possibility confers to them the status of active packaging. Two different film forming biopolymers, gluten and iota-carrageenans, have been compared. D-limonene was added to the two film formulations and its release kinetics from emulsion based edible films was assessed with HS-SPME. Results obtained for edible films were compared with D-limonene released from the fatty matrix called Grindsted Barrier System 2000 (GBS). Comparing iota-carrageenans with gluten emulsified film, the latter showed more interesting encapsulating properties: in fact, D-limonene was retained by gluten film during the process needed for film preparation, and it was released gradually during analysis time. D-limonene did not show great affinity to iota-carrageenans film, maybe due to high aroma compound hydrophobicity. Carvone release from the three different matrices was also measured to verify the effect of oxygen barrier performances of edible films to prevent D-limonene oxidation. Further investigations were carried out by FT-IR and liquid permeability measurements. Gluten film seemed to better protect D-limonene from oxidation. Gluten-based edible films represent an interesting opportunity as active packaging: they could retain and release aroma compounds gradually, showing different mechanical and nutritional properties from those of lipid based ingredients.
    No preview · Article · Nov 2012 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: The effects of three preparation techniques on the oenological properties of a yeast autolysate were investigated: enzymatic autolysis, thermolysis, and the combination of a slow freezing-defrosting and mechanical disruption were carried out on a commercial formulation of active dry yeasts (Saccharomyces cerevisiae). The powders obtained by freeze drying, were characterized: volatile compounds were analyzed by SPME-GC with mass spectrometric (MS) and olfactometric detection (O); the release of colloids in winelike solution was studied by SDS-PAGE and size exclusion chromatography (SEC). Finally, the effects of the powders addition on the aroma composition of a white wine were investigated by SPME-GC-MS, SPME-GC-O, and sensory evaluation. The products obtained were quite different from each other. In particular, enzymatic autolysis led to higher contents of nonglycosilated soluble proteins in the powders and determined a higher retention of wine aroma compounds. On the contrary, thermal autolysate was richer in glycoproteins, and it was able to increase the wine aroma intensity; nevertheless, in the wines treated with such preparation, a slight yeastlike olfactory note was perceived.
    No preview · Article · Mar 2012 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: The addition of a commercial yeast autolysate to a model solution of five typical wine aroma compounds (ethyl octanoate, linalool, 2-phenylethanol, β-ionone and octanoic acid) was investigated considering different variables, such as temperature, pH and the presence of highly concentrated natural volatile substances in wine (e.g. 3-methyl-1-butanol). The interactions of such compounds with both yeast walls and released colloids were studied using gas chromatography, with liquid-liquid extraction and solid-phase microextraction. The results were compared with those obtained by adding the commercial product to a white table wine, spiked with the five standard compounds. The data confirmed that yeast walls mainly bind less polar molecules: their loss in synthetic medium seemed to increase at higher pH values. Temperature and pH affected differently the interactions between yeast colloids and volatile compounds in wine and model solution: in complex solutions (as the addition of 3-methyl-1-butanol demonstrated) the interaction mechanisms could be influenced by competitive or other matrix-related effects, which can reduce the binding of single compounds, or even enhance their volatility.
    Preview · Article · Jul 2011 · Food Chemistry
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    ABSTRACT: Some modifications to a previous nondestructive colorimetric method that permits evaluation of the oxygen diffusion rate through wine closures were proposed. The method is based on the reaction of indigo carmine solution with oxygen and the tristimulus measurement of the consequent color change. Simplified preparation and measurement procedures were set up, allowing the analysis of a large number of samples simultaneously. The method was applied to the evaluation of the variability within the lot of 20 different types of stoppers (synthetic, produced by molding, and natural cork). The closures were tested at a storage temperature of 26 degrees C. With regard to oxygen permeability, the natural cork stopper showed a low homogeneity within the lot, especially during the first month after bottling, whereas the synthetic closure showed a greater steadiness in the performance. The limits of the colorimetric method were also analyzed, and three possible causes of degradation of the indigo carmine solution were identified: oxygen, light, and heat.
    No preview · Article · Feb 2010 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: Aglianico del Vulture wines are typical and promising production of Basilicata Province. Nevertheless, its potential quality is often affected by the presence of a strong honey-like odour. This problem was studied using SPME-GC-MS and SPMEGC- O; ethyl phenylacetate (EPhA), was identified as the main responsible of this olfactory character. This volatile compound is detectable in all wines, but it is particularly abundant in Aglianico wines; its sensory threshold was determined. Moreover, in order to study the relationship between EPhA concentration and wine sensory perception, another sensory test was performed on Aglianico wines affected by different levels of defect: an Attribute Difference Test. EPhA concentrations higher than the detected sensory threshold (about 70 ?g L-1) gave to the wines a strong honey-like character, that seemed to compromise its pleasantness. Further deepening are necessary to study the main variables connected to the formation of this compound in Aglianico, and to suggest possible technological approaches to reduce the problem.
    No preview · Article · Oct 2007 · Acta horticulturae
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    ABSTRACT: Interest in high-quality and peculiar products is a recent trend in the enological field; for this reason, production of wines from autochthonous vine varieties is requested by consumers. Aglianico wine from the Italian region "Basilicata" is an example of a promising product strictly connected to the territory; nevertheless, it is affected by a frequent sweet-like off-flavor. In this study the compositional cause of this off-flavor was investigated by SPME-GC-olfactometry, SPME-GC-MS, and sensory tests. Ethyl phenylacetate (EPhA) was found to be the compound mainly responsible, and its sensory threshold was determined near 73 microg/L; products with the odorant concentration near and up to these values were always recognized as significantly different from the other wines and were often far from wine technical pleasantness; besides EPhA gave to the wines a strong honey-like character. Some preliminary hypotheses about its mechanism of formation (shikimate pathway) are presented in this study: these hypotheses could explain the correlation between EPhA and volatile phenols that was found by both sensory tests and GC quantitative analysis of wines affected by different levels of defect.
    No preview · Article · Jul 2007 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: A qualitative study of volatile compounds in three commercial yeast extracts and autolysates was performed by solid-phase microextraction-gas chromatography with mass spectrometric and olfactometric detection; their addition to white wines and their effect on wine aroma composition were investigated by analytical, olfactometric and sensory evaluations. More than 160 volatile compounds were detected in the headspace of the commercial powders (some not previously reported in literature), and their olfactory characters were described. Yeast derivatives strongly modified wine aroma composition, either affecting the volatility of wine aroma compounds or by releasing exogenous volatiles. Dosage appeared to be fundamental: low amounts increased the volatility of some esters, giving more flowery and fruity notes to the wine; higher amounts increased fatty acid content in the wine headspace, producing yeasty, herbaceous and cheese-like smells. Sensory tests demonstrated that yeast derivatives would not be suitable for wines with a typical varietal aroma.
    No preview · Article · Dec 2006 · Food Chemistry

  • No preview · Article · Jan 2006
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    ABSTRACT: Different novel fibers for solid-phase microextraction were developed in the last years. The aims of this work were the study of their performances in wine headspace analysis, and the optimization of some analytical conditions. The fibers were evaluated for their sensitivity and repeatability; the results showed a strongly different behavior for the different solid-phases, both for the different zones of the chromatogram and for different levels of concentration. A Divinylbenzene/Carboxen/Polydimethylsiloxane fiber coating appeared the most suitable for the analysis of aromatic fraction of wines in its totality. For specific applications, the choice of a suitable solid-phase, depends on the class of compounds be analyzed.
    No preview · Article · Nov 2005 · Food Chemistry
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    ABSTRACT: The use of yeast polysaccharides in the stabilization of the phenolic fraction of red wines, is a recent application. Increasing amounts of an industrial product made by thermal lysis of yeast cell walls were added to two red wines: the effects on phenolic and coloring fraction were studied, in relation to bottle storage. The effects on wine color and astringency, showed strongly dependence to the characteristics of the wine and to the dosage; they were limited to short times of conservation. In fact, a loss in the positive effects on color intensity was observed during the bottle storage, probably as a result of the modifications in the colloidal equilibrium during conservation. The complexity of the conditioning factors makes other studies necessaries, in order to optimize this kind of technology.
    No preview · Article · Apr 2005 · Journal International des Sciences de la Vigne et du Vin
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    ABSTRACT: Headspace analysis of white truffle (Tuber magnatum Pico) using solid-phase micro extraction (SPME) together with gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS) allowed some typical compounds of these fungi to be identified and characterised. Bis(methylthio)methane and dimethyl sulphide (DMS) were the most important compounds from both a quantitative and qualitative point of view. Dimethyl sulphoxide (DMSO), dimethyl sulphone and (methylsulfinyl)(met hylthio)methane were identified for the first time in white truffle. The results of headspace analysis of fresh and stored white truffles showed very important changes in the aroma profile, with the formation or increase of several compounds including alcohols and acids.
    No preview · Article · Jan 2005 · Italian Journal of Food Science
  • Roberto Zironi · Lara Tat
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    ABSTRACT: Durante mucho tiempo, la producción italiana de espumosos, los reconocidos como spumanti, ha sido considerada como un pariente pobre del más noble y renombrado champán francés. En los últimos años se observa una importante revalorización de la «tradición nacional» en este sector, gracias al descubrimiento, en este producto, de aquellos perfumes y aromas característicos de las diversas zonas de producción que tanto atraen al consumidor. Y es que, además de los espumosos, Italia cuenta con una remarcable producción de vinos frisantes o de aguja, que se diferencian de los primeros por la cantidad de anhídrido carbónico que contienen.
    No preview · Article · Jan 2005

  • No preview · Article · Oct 2004 · Sciences des Aliments
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    ABSTRACT: Polysaccharides play an important role in wine stability, due to their ability to take part in colloidal equilibrium ; addition of yeast derivative products are a novel rapid way to enrich colloidal structure of white wines and to increase their stability. Different amounts of an industrial formulate made by thermal lysis of yeast cell walls, and their effects on tartaric and protein stability were evaluated for three white wines, fifteen days and ten months after bottling. The lysate had some good stabilizing properties in the short period, but it determined a loss in stability of wines in long storage conditions (both tartaric and protein) ; this effect was strongly affected by dosage. A possible explanation could be linked to interactions between colloidal particles determining an increase in their size during storage time ; the consequent precipitation phenomena could determine a loss in stabilizing factors of wines during bottle storage ; this effect seemed to be emphasized by the added lysate.
    No preview · Article · Jan 2004 · Sciences des Aliments