Browsing by Author "Urtubia, Alejandra"

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    Exploring the applicability of MIR spectroscopy to detect early indications of wine fermentation problems
    (ELSEVIER SCI LTD, 2008) Urtubia, Alejandra; Perez correa, J. Ricardo; Pizarro, Francisco; Agosin, Eduardo
    In this study we explore the applicability of MIR technology to detect early indications of wine fermentation problems. An oenologist could improve the chances of a vinification process finishing optimally if anomalies are detected early. A comparative analysis of three fermentations with artificial musts was performed; one of normal behaviour, one subject to a temperature gradient, and the third deficient in assimilable nitrogen. We tracked each fermentation through changes in spectra in addition to changes in must composition. It was easier to detect anomalous behaviour by monitoring wine metabolite concentrations than through direct spectra analysis, nevertheless, calibrations needed to be derived from fermenting must samples and so cost more. All measured compounds (glucose, fructose, ethanol, glycerol, succinic and acetic acids) exhibited behavioural changes at 30 h of fermentation in nitrogen deficient musts. Temperature deviations were reflected in the anomalous behaviour of ethanol, glycerol, succinic acid and acetic acid. (c) 2007 Elsevier Ltd. All rights reserved.
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    Influence of Organic Nitrogen Derived from Recycled Wine Lees and Inorganic Nitrogen on the Chemical Composition of Cabernet Sauvignon Wines Fermented in the Presence of Non-Saccharomyces Yeasts Candida boidinii, C. oleophila, and C. zemplinina
    (Multidisciplinary Digital Publishing Institute (MDPI), 2024) López Lira, Claudia; Valencia, Pedro; Urtubia, Alejandra; Landaeta Campos, Esteban Alonso; Tapia, Ricardo A.; Franco Melazzini, Wendy Verónica
    In this study, the influences of inorganic nitrogen source (INS) and organic nitrogen source (ONS) supplementation during the wine fermentation process using three non-Saccharomyces yeasts (Candida zemplinina, Candida oleophila, and Candida boidinii) were analyzed. Diamine phosphate (DAP) was used as an INS, and lees enzymatic hydrolysate was used as an ONS. Complete alcoholic fermentation and a higher concentration of volatile compounds were obtained in fermentations with ONS, mainly esters from 81 to 4564 µg/L, alcohols from 231 to 7294 µg/L, and isoamyl acetate ester compounds from 12.3–22.8 ppb, with a very marked odorant activity value (OAV). In addition, malic acid was detected due to its influence on yeast metabolism and, consequently, on aroma production. Using a Y15 enzymatic autoanalyzer, residues of 1.30 g/L in ONS and 1.35 g/L in INS were obtained on the last day of alcoholic fermentation. In summary, we obtained promising results concerning the production of wine with enhanced functionalities due to higher concentrations of some volatile and polyphenolic compounds.
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    Screening and Selection of Native Lactic Acid Bacteria Isolated from Chilean Grapes
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025) Vargas Luna, Carla; Godoy, Liliana; Benavides, Sergio; Ceppi de Lecco, Consuelo; Urtubia, Alejandra; Franco, Wendy
    © 2025 by the authors.The aim of this study was investigating the biological diversity of lactic acid bacteria isolated from Chilean grapes and identifying potential candidates for use as malolactic fermentation starter cultures. The isolated bacteria underwent a comprehensive six-stage screening process, which was mutually exclusive except for the evaluation of tyramine production and citric acid intake. This process included morphological, metabolic, fermentation yield, and resistance tests to identify promising malolactic strains. Morphological assessments led to the selection of 23 isolates, which were genetically identified as Levilactobacillus brevis (65% abundance) and Leuconostoc mesenteroides (35% abundance). Among these, eight strains exhibited low sugar metabolism rates, while three demonstrated competitive growth and malolactic activity in a synthetic medium containing 10% ethanol, outperforming a commercial strain. Low consumption was observed in the qualitative citric acid intake test, whereas a positive response was noted for tyramine production. At the conclusion of the sequential selection criteria, Levilactobacillus brevis BCV-46 exhibited the most favorable characteristics for potential use as a malolactic starter culture, successfully withstanding the combined stress factors of ethanol, pH, and SO2.
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    Technical Feasibility of Glucose Oxidase as a Prefermentation Treatment for Lowering the Alcoholic Degree of Red Wine
    (2017) Valencia, Pedro; Espinoza, Karen; Ramírez, Cristián; Franco, Wendy; Urtubia, Alejandra
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    Using data mining techniques to predict industrial wine problem fermentations
    (ELSEVIER SCI LTD, 2007) Urtubia, Alejandra; Perez Correa, J. Ricardo; Soto, Alvaro; Pszczolkowski, Philippo
    Winemakers currently lack the tools to identify early signs of undesirable fermentation behavior and so are unable to take possible mitigating actions. Data collected from tracking 24 industrial fermentations of Cabernet sauvignon were used in this study to explore how useful is data mining to detect anomalous behaviors in advance. A database held periodic measurements of 29 components that included sugar, alcohols, organic acids and amino acids. Owing to the scale of the problem, we used a two-stage classification procedure. First PCA was used to reduce system dimensionality while preserving metabolite interaction information. Cluster analysis (K-Means) was then performed on the lower-dimensioned system to group fermentations into clusters of similar behavior. Numerous classifications were explored depending on the data used. Initially data from just the first three days were assessed, and then the entire data set was used. Information from the first three days' fermentation behavior provides important clues about the final classification. We also found a strong association between problematic fermentations and specific patterns found by the data mining tools. In short, data from the first three days contain sufficient information to establish the likelihood of a fermentation finishing normally. Results from this study are most encouraging. Data from many more fermentations and of different varieties needs to be collected, however, to develop a reliable and more broadly applicable diagnostic tool. (c) 2006 Elsevier Ltd. All rights reserved.