Publications by authors named "Isabel Lopez-Alfaro"

Cork taint provides off-odors and changes negatively wine composition. In fact, it is one of the most important causes of discarding bottled wine. 2,4,6-Trichloroanisole (TCA) is the most known molecule responsible of that problem.

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In winemaking, excessive production of acetic acid by acetic acid bacteria poses a major challenge, leading to rejection of wine by consumers. The aim of this study was to devise an economically viable and easy-to-use liquid culture medium for the preventive detection of microorganisms capable of generating acetic acid in wine. The modified medium incorporated specific nutrients that favored the growth of acetic acid bacteria and increased selectivity.

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The aim of the study was to determine the differences in the microbiological, physical-chemical, aromatic and phenolic composition between two winemaking methods: carbonic maceration and the standard method of destemming and crushing. We analysed 84 commercial Rioja wines made from the Tempranillo grape variety during the 2017 vintage, 40 had been made by carbonic maceration and 44 by destemming and crushing. Despite the heterogeneity within the two groups of wines, it was possible to differentiate between them.

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The phenolic compounds of red wines are responsible for their color, astringency, and antioxidant properties. The fermentative yeasts might be used to modulate wines in terms of their color, aroma and probably healthy properties. In this study, six non- species were tested because they might enhance the properties of red Tempranillo wines from Rioja.

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Nine non-Saccharomyces yeasts belonging to 6 species (Torulaspora delbrueckii, Metschnikowia pulcherrima, Lachancea thermotolerans, Zygosaccharomyces bailii, Williopsis pratensis and Candida zeylanoides) and two mixed inoculum of T. delbrueckii and L. thermotolerans were screened for aroma formation and fermentative behaviour in sequential inoculations with Saccharomyces cerevisiae.

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Background: This research was aimed to study the influence on grape and wine quality and on the fermentation processes of the application of a preventive biological treatment against Botrytis cinerea in Tempranillo Rioja grapevines. For this purpose, a biofungicide containing Bacillus subtilis QST713 was applied twice to the vineyard.

Results: Results were compared with non-treated samples from the same vineyard and with samples treated with a chemical fungicide composed of fenhexamid.

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This study was aimed to measure the impact of the application of a bio-fungicide against on the microbiota involved in the alcoholic fermentation (AF) of Tempranillo Rioja wines. For this purpose, a bio-fungicide composed of the biological control bacterium QST713 was applied to the vineyard. The microbial diversity was analyzed from grape biofilm to wine.

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This study was performed with the aim of reducing the microbial communities of wines after alcoholic fermentation to improve the establishment of commercial Oenococcus oeni inoculum for developing the malolactic fermentation. Microbial community reduction was accomplished by applying Pulsed Electric Field (PEF) technology to four different wines. Overall, significant reductions in yeast population were observed.

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Ninety-seven non- wine yeast strains belonging to ten different genera and species ( spp. and spp.; , , , , and were screened for 13 enzymes related to wine aroma, color and clarity.

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The main aim of this study was to describe the impact of foliar phenylalanine and urea application on grape and must microbial populations. The tool used to perform the ecological study was DGGE conducted with several infusions in non-enriched and enriched liquid media, as well as direct DNA extractions of grapes and musts. A total of 75 microbial species were found in the study.

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The Oenococcus oeni populations of Tempranillo wines from Castilla La Mancha and La Rioja winemaking regions were analysed from one to three years and up to ten wineries. The objective was to evaluate the genetic variability and the O. oeni population structure.

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The importance of phenolic compounds for grape and wine quality has drawn attention to studying different practices with the aim of increasing their content. Cluster application of elicitors is a viticultural practice that has shown promising results in recent years. However, cluster application requires a previous defoliation, which is time-consuming and expensive.

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The presence and distribution of genotypes from malolactic starter cultures between the autochthonous microbiota in fermenting Rioja wines have been studied in this paper. The commercial cultures characterization allowed to identify different species and common pulsed field gel electrophoresis and randomly amplified polymorphic DNA genotypes in several brands of Oenococcus oeni starter cultures. Four indistinguishable genotypes were found between the commercial and the autochthonous O.

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Oenococcus oeni is usually the main lactic acid bacteria (LAB) responsible for conducting malolactic fermentation (MLF) in wines. Pulsed Field Gel Electrophoresis (PFGE) is one of the most common methods used to identify different genotypes among the wine LAB populations. Although PFGE is a powerful typing tool, it is time-consuming and its results are not easily exchangeable between laboratories so typing methods such as Multilocus Sequence Typing (MLST) have been developed.

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The purpose of this paper was to study the effect of pulsed electric fields (PEF) on the stilbene content of three grape varieties. For this purpose, four different PEF treatments were applied using a continuous system over three varieties, Graciano, Tempranillo and Grenache, destemmed and crushed. In addition, the influence of PEF on their physicochemical composition was studied.

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Lactic acid bacteria populations of red wine samples from industrial fermentations, including two different vinification methods were studied. For this investigation, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis was employed to supplement previous results that were obtained by culture-dependent methods. PCR-DGGE was aimed to study two targeted genes, 16S ribosomal DNA (rDNA) and rpoB, and the results were useful to evaluate the microbial populations in wine samples.

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Ecology of the lactic acid bacteria (LAB) during alcoholic fermentation (AF) and spontaneous malolactic fermentation (MLF) of Tempranillo wines from four wineries of La Rioja has been studied analyzing the influence of the winemaking method, processing conditions, and geographical origin. Five different LAB species were isolated during AF, while, during MLF, only Oenococcus oeni was detected. Although the clonal diversity of O.

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Diversity of lactic acid bacteria (LAB) species has been analyzed for three consecutive years (2006, 2007, and 2008) during alcoholic and malolactic fermentations of Tempranillo wine in a winery at La Rioja. The results showed differences in malolactic fermentation duration, and in both diversity of LAB species and diversity of Oenococcus oeni genotypes. O.

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