Lucía González-Arenzana

Pulsed electric field treatment enhanced stilbene content in Graciano, Tempranillo and Grenache grape varieties

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. PEF treatments did not affect the pH or total acidity of Graciano, however, musts from Tempranillo and Grenache had higher pH values and lower total acidity. In the three varieties, all treatments resulted in an increase of potassium content, deeper colour intensity and total polyphenol index and lower tonality, more pronounced in the treatments with higher time and energy. The stilbene content of the must significantly increased with respect to the control. This increase depended on the variety and the treatment applied. Tempranillo increased up 200% the total stilbene concentration, Grenache 60% and Graciano 50%. For the three varieties, the treatment with the highest time and energy was the most effective on the total stilbene extraction. These results indicate that PEF could be a suitable technology for obtaining musts with deeper colour and higher phenolic content, including resveratrol and piceid.

Phenylalanine and urea foliar applications to grapevine: effect on wine phenolic content.

Phenolic compounds play a key role in the organoleptic properties of wines. Viticultural practices may influence grape and wine phenolic content, thus determining their quality. The objective of this study was to evaluate the effect of foliar applications of phenylalanine and urea, at two different doses, on wine phenolic composition. Grapes were harvested at their optimal technological maturity and their respective wines were elaborated at small scale. Wine detailed phenolic composition was determined. Results revealed that the content of several anthocyanins and flavonols was enhanced by the application of both phenylalanine doses and by the application of the low dose of urea. In contrast, flavanols and non-flavonoid compounds were less affected by the foliar treatments. The findings seem to be related to the time of application, since anthocyanins and flavonols are accumulated after veraison. In conclusion, nitrogen foliar fertilization increased the phenolic content of Tempranillo wines. This could be of interest since anthocyanins and flavonols are associated with wine quality, especially with its color.

Genomic diversity of Oenococcus oeni populations from Castilla La Mancha and La Rioja Tempranillo red wines.

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. For this purpose a MLST scheme based on four loci (gyrB, purK, pgm and recP genes) and PFGE with SfiI restriction enzyme were developed for later combination. The results showed an O. oeni population completely adapted to winemaking regions. A purifying selection influenced the genes evolution, especially recP that along with purK were the most interesting loci to analyse the genetic variability of the isolates. In this way linkage disequilibrium and intergenic and intragenic recombination were determined between isolates. PFGE typing with UPGMA data were not coincident with the phylograms assessed for MLST by Maximum likelihood and combination of both techniques differentiated all the isolates as strains. Those results led the research to conclude that O. oeni population from CM and LR was a panmictic population with a slight clonal evolution, so subpopulations could not be described. A broader study including more winemaking regions with different grape varieties and distinct ways of elaborating would be interesting to complete the knowledge about O. oeni populations.

Ecology of Indigenous Lactic Acid Bacteria along Different Winemaking Processes of Tempranillo Red Wine from La Rioja (Spain)

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. oeni strains was moderate, mixed populations were observed, becoming at least one strain with distinct PFGE profile the main responsible for MLF. Neither the winemaking method nor the cellar situation was correlated with the LAB diversity. However, processing conditions influenced the total number of isolates and the percentage of each isolated species and strains. The winemaking method could cause that genotypes found in semicarbonic maceration did not appear in other wineries. Four genotypes of O. oeni were isolated in more than one of the rest wineries. These four together with other dominant strains might be included in a future selection process.

Molecular analysis of Oenococcus oeni and the relationships among and between commercial and autochthonous strains

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. oeni strains. These four genotypes appeared during different vintages in seven of the 10 sampled wineries despite bacterial starter cultures had never been used. Therefore, the detection of commercial LAB genotypes indistinguishable from the autochthonous ones involved their removal from a selection process. These genotypes represented the 17.7% of autochthonous O. oeni isolated in this region during three consecutive years. This fact demonstrated that performing similar studies as previous selection criteria is advisable to avoid large work and the proposal of one commercialized bacteria.

Wine aromatic compound production and fermentative behaviour within different non-Saccharomyces species and clones.

Twenty‐five enological yeasts belonging to nine different species (Candida zeylanoides, Cryptococcus uzbekistanensis, Debaryomyces hansenii, Lachancea thermotolerans, Metschnikowia pulcherrima, Torulaspora delbrueckii, Williopsis pratensis, Zygosaccharomyces bailii and Saccharomyces cerevisiae) were screened for aroma formation and fermentative behaviour as part of a non‐Saccharomyces yeast selection programme.

Lactic acid bacteria communities in must, alcoholic and malolactic Tempranillo wine fermentations, by culture-dependent and culture-independent methods

The lactic acid bacteria (LAB) communities from must and through alcoholic (AF) and malolactic fermentations (MLF) of Tempranillo red wines were studied in ten wineries from the Designation of Origin Rioja during three consecutive vintages. A statistical study with data from both methods, PCR-DGGE and plating, was performed. Results showed that the LAB community in the D.O. Rioja was highly determined by the type of fermentation and also by the different stages within the winemaking, while other factors such as year, winery, or sampling subzones had not significant effect on the LAB species distribution. Three microbial families, seven genera, and 25 species were described in this research, and Lactobacillus was the most commonly detected genus before MLF. Curiously, genera and species not frequently detected in wines as Weissella, Fructobacillus, and Oenococcus kitaharae were identified during AF, and no-Oenococcus oeni species were described in some MLF by both methods. For the first time, two new O. oeni allelic groups were determined by 16S rDNA/DGGE being randomly adapted to the wine environment. Further studies targeted to understand the implication of the novel species, and O. oeni allelic groups in Rioja wine fermentations could be really interesting.

Application of the Different Electrophoresis Techniques to the Detection and Identification of Lactic Acid Bacteria in Wines

© 2012 Gonzalez-Arenzana et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Application of the Different Electrophoresis Techniques to the Detection and Identification of Lactic Acid Bacteria in Wines

Microbial inactivation and MLF performances of Tempranillo Rioja wines treated with PEF after alcoholic fermentation

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. To a lesser extent, lactic acid bacteria were reduced while acetic acid bacteria were completely eliminated after the PEF treatment. In three out of the four tested wines, a decrease in the competitive pressure between microorganisms due to the detected reduction led to a general but slight shortening of the malolactic fermentation duration. In the wine with the most adverse conditions to commercial starter establishment, the shortest malolactic fermentation was reached after PEF treatment. Finally, the sensorial quality of three out of the four treated wines was considered better after the PEF treatment. Therefore, PEF technology meant an important tool for improving the malolactic fermentation performance.

Screening of enzymatic activities within different enological non-Saccharomyces yeasts

Abstract Ninety-seven non-Saccharomyces wine yeast strains belonging to ten different genera and species (Candida spp. and Criptococcus spp.; Debaryomyces hansenii, Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia kluyveri, Sporidiobolus salmonicolor, Torulaspora delbrueckii, Williopsis pratensis and Zygosaccharomyces bailii) were screened for 13 enzymes related to wine aroma, color and clarity. Understanding the yeasts’ influence in these wine characteristics provides a platform for selecting strains for their development as starter cultures and for the management of alcoholic fermentation. Most of the strains showed the presence of one or more enzymes of biotechnological interest. Our screening demonstrated several intraspecific differences within the yeast species investigated, indicating that strain selection is of great importance for their enological application, and also that some non-Saccharomyces that have not been thoroughly explored, may deserve further consideration. This research represents the first stage for selecting non-Saccharomyces strains to be used as a starter along with Saccharomyces cerevisiae to enhance some particular characteristics of wines.