Search results for " winemaking"
showing 10 items of 110 documents
AcetyltransferaseSAS2and sirtuinSIR2,respectively, control flocculation and biofilm formation in wine yeast
2014
Cell-to-cell and cell-to-environment interactions of microorganisms are of substantial relevance for their biotechnological use. In the yeast Saccharomyces cerevisiae, flocculation can be an advantage to clarify final liquid products after fermentation, and biofilm formation may be relevant for the encapsulation of strains of interest. The adhesion properties of wine yeast strains can be modified by the genetic manipulation of transcriptional regulatory proteins, such as histone deacetylases, and acetylases. Sirtuin SIR2 is essential for the formation of mat structures, a kind of biofilm that requires the expression of cell-wall protein FLO11 as its deletion reduces FLO11 expression, and ad…
Study of the First Hours of Microvinification by the Use of Osmotic Stress-response Genes as Probes
2002
Summary When yeast cells are inoculated into grape must for vinification they find stress conditions because of osmolarity, which is due to very high sugar concentration, and pH lower than 4. In this work an analysis of the expression of three osmotic stress induced genes ( GPD1 , HSP12 and HSP104 ) under microvinification conditions is shown as a way to probe those stress situations and the regulatory mechanisms that control them. The results indicate that during the first hours of microvinification there is an increase in the GPD1 mRNA levels with a maximum about one hour after inoculation, and a decrease in the amount of HSP12 and HSP104 mRNAs, although with differences between them. The…
A new PCR-based method for monitoring inoculated wine fermentations.
2003
A new PCR-based method has been developed to monitor inoculated wine fermentations. The method is based on the variation in the number and position of introns in the mitochondrial gene COX1. Oligonucleotide primers homologous to the regions flanking the Saccharomyces cerevisiae COX1 introns have been designed and tested for S. cerevisiae wine yeast strain differentiation. Four primers were selected for their subsequent use in a multiplex PCR reaction and have proved to be very effective in uncovering polymorphism in natural and commercial yeast strains. An important point is that the speed and simplicity of the technique, which does not require the isolation of DNA, allows early detection o…
Pneumatic press equipped with the Vortex system for white grapes processing: First results
2019
The interaction between mechanical, computer and electronic technologies offers nowadays highly innovative solutions to be applied to the oenological machinery industry. Grapes pressing for the extraction of must from the grapes has a fundamental role for obtaining wines with high quality. The pneumatic presses commonly used work with a discontinuous cycle, taking on average about 3 hours for the extraction of the juice from the grapes. During this period, the presence of oxygen in contact with grapes can modify the qualitative characteristics of the future wine. The aim of the research was to study the “Vortex System” applied to a pneumatic press and to evaluate the quality of wines obtain…
Influence of grape transport and destemming systems on the quality of Chardonnay wines
2016
The winemaking technology plays a very important role in enology as it directly influences the characteristics of wine. In particular, grape transport and destemming are critical steps in winemaking for the wine quality. The aim of this study was to compare two different processing lines of Chardonnay grapes to evaluate their effects on the quality of the final product. In particular, grapes receiving, transporting and destemming were performed using different machines in order to evaluate their influence on the quality of Chardonnay wines. The use of a receiving hopper equipped with a belt conveyor, followed by a destemmer equipped with partially coated rubber beaters, allowed to obtain Ch…
Immobilised Cell Technology in Winery and Fruit Wine Production
2006
Winemaking is largely concerned with the progress of biotechnology and especially with the use of high cell density reactors. Entrapment is the most widely method to immobilise cells; several matrix can be used (alginate, carrageenan, agar) with different geometry (beads, fibres, plates). Alcoholic fermentation of wine, malolactic fermentation, bottle fermentation known as the "Methode champenoise" and sparkling wines are among the industrial applications. Whereas prospects for this technology appear encouraging, further research is needed to optimise reaction variables, improve the long-term stability of the reactors, and understand more about secondary metabolite production by yeasts unde…
Quantifying the individual effects of ethanol and temperature on the fitness advantage of Saccharomyces cerevisiae
2011
The presence of Saccharomyces cerevisiae in grape berries and fresh musts is usually very low. However, as fermentation progresses, the population levels of this species considerably increase. In this study, we use the concept of fitness advantage to measure how increasing ethanol concentrations (0-25%) and temperature values (4-46 °C) in wine fermentations affects competition between S. cerevisiae and several non-Saccharomyces yeasts (Hanseniaspora uvarum, Torulaspora delbrueckii, Candida zemplinina, Pichia fermentans and Kluyveromyces marxianus). We used a mathematical approach to model the hypothetical time needed for S. cerevisiae to impose itself on a mixed population of the non-Saccha…
Oxidative stress responses and lipid peroxidation damage are induced during dehydration in the production of dry active wine yeasts.
2009
The tolerance of the yeast Saccharomyces cerevisiae to desiccation is important for the use of this microorganism in the wine industry, since active dry wine yeast is routinely used as starter for must fermentations. Many studies have shown the complexity of the cellular effects caused by water loss, including oxidative injuries on macromolecular components. However the technological interest of yeast drying was not addressed in those studies, and the dehydration conditions were far from the industrial practice. In the present study a molecular approach was used to characterize the relevant injuring conditions during pilot plant dehydrations under two different drying temperatures (i.e., 35…
DNA chips for yeast biotechnology. The case of wine yeasts.
2002
The yeast Saccharomyces cerevisiae is one of the most popular model organisms. It was the first eukaryote whose genome was sequenced. Since then many functional analysis projects have tried to find the function of many genes and to understand its metabolism in a holistic way. Apart from basic science this microorganism is of great interest in several biotechnology processes, such as winemaking. Only global studies of the cell as a whole can help us to understand many of the technical problems facing winemaking. DNA chip technology is one of the most promising tools for the analysis of cell physiology. Yeast has been the model organism for the development of this technique. Many of the studi…
Aroma production and fermentation performance of S. cerevisiae × S. kudriavzevii natural hybrids under cold oenological conditions
2019
This work aims to describe the wine fermentation characteristics of 23 natural S. cerevisiae × S. kudriavzevii hybrid yeasts related to fermentative environments isolated from different regions and their significance for the aroma spectra of the produced wines. Fermentations were performed at 12 °C in artificial must, and S. cerevisiae and S. kudriavzevii pure species strains were used for comparison purposes. We determined the relevant kinetic parameters of fermentation, the concentration of the main metabolites and the main aroma-related compounds produced after fermentation. The results revealed that some strains that show well-rounded characteristics could be profitable yeast starters f…