Control Of Alcoholic Fermentation Research Articles

Starmerella bacillaris Released in Vineyards at Different Concentrations Influences Wine Glycerol Content Depending on the Vinification Protocols.

Starmerella bacillaris is a non-Saccharomyces yeast proposed for must fermentation together with Saccharomyces cerevisiae because of its high glycerol and moderate volatile acidity production. Furthermore, it was demonstrated that the same S. bacillaris strains that possess interesting technological properties exhibited antifungal activity against Botrytis cinerea, suggesting the release of this yeast in the vineyard. To obtain a positive effect during the following winemaking process, the maintenance of suitable concentrations of S. bacillaris is essential. Therefore, to obtain information on the survival of S. bacillaris, a small-scale field trial was performed. One week before the harvest, two different concentrations of S. bacillaris (106 and 107 cells/mL) were sprayed on Pinot grigio bunches, and the strain concentration was monitored by means of qPCR during the subsequent fermentation process. In addition, the combined effect of different winemaking techniques was evaluated, i.e., the vinification of juice, juice with marc and cryomaceration treatment. Results demonstrated that, under the tested conditions, S. bacillaris released in the vineyard remained viable for one week on grape bunches and increased glycerol content during the subsequent fermentation process. Different vinification protocols influenced cell concentrations. In particular, the cryomaceration treatment, due to the use of low temperature, supported S. bacillaris growth due to its cryotolerant aptitude. The collected data open new perspectives on the control of alcoholic fermentation, involving both vineyard and cellar management.

Microbiological control of alcoholic fermentation

Alcoholic fermentation and the production of wine has accompanied humanity for more than 10000 years. However, it has been only in the last 50 years when the winemakers have had the tools to manage and control the process. The methodology to analyze and monitor the succession of the microorganisms that participate in the process along with the effective use of antimicrobial compounds (for instance sulfur dioxide), the control of the temperature and, above all, the use of cellar-friendly fermentation starters (mostly as Active Dry Wine Yeast) have provided the appropriate conditions for that control. However, the use of a limited number of commercial presentations of the starters has generated an unwanted uniformity of the wines produced. Furthermore, new tendencies in wine making with limited or no human intervention have considered these tolls as a negative aspect in the wine quality, although most of these concerns are only philosophical, without clear scientific evidence. We present a revision of the present state of the art in these methodologies where our research group has been working for the last 25 years.

Massive Sequencing: A New Tool for the Control of Alcoholic Fermentation in Wine?

In wine industry, there is a prevalent use of starter cultures to promote a controlled and efficient alcoholic fermentation preventing the growth of spoilage microbes. However, current trends in enology aim to combine the guaranteed success of monitored process and the complexity of fermentations either by inoculating autochthonous starters or by performing spontaneously to produce distinctive wines. To understand the complex roles of microorganisms on wine fermentation, we must understand their population dynamics and their relationships with wine quality and metabolome. Current metagenomics techniques based on massive sequencing are gaining relevance to study the diversity and evolution of microbial population on every stage of the wine making process. This new tool and technique increases the throughput and sensitivity to study microbial communities. This review focuses on the current knowledge about wine alcoholic fermentation, the contribution of massive sequencing techniques and the possibility of using this tool for microbial control.

Pleiotropic functions of the yeast Greatwall-family protein kinase Rim15p: a novel target for the control of alcoholic fermentation.

Rim15p, a Greatwall-family protein kinase in yeast Saccharomyces cerevisiae, is required for cellular nutrient responses, such as the entry into quiescence and the induction of meiosis and sporulation. In higher eukaryotes, the orthologous gene products are commonly involved in the cell cycle G2/M transition. How are these pleiotropic functions generated from a single family of protein kinases? Recent advances in both research fields have identified the conserved Greatwall-mediated signaling pathway and a variety of downstream target molecules. In addition, our studies of S. cerevisiae sake yeast strains revealed that Rim15p also plays a significant role in the control of alcoholic fermentation. Despite an extensive history of research on glycolysis and alcoholic fermentation, there has been no critical clue to artificial modification of fermentation performance of yeast cells. Our finding of an in vivo metabolic regulatory mechanism is expected to provide a major breakthrough in yeast breeding technologies for fermentation applications.

Non-Saccharomyces Yeasts in Controlled Mixed Culture Fermentation in Winemaking: the Role of Metabolic Interactions

One of the most important technological advances in winemaking is the control of alcoholic fermentation through the inoculation of the grape juice with selected cultures of Saccharomyces cerevisiae . In the last decade several studies revaluated the involvement of non- Saccharomyces yeasts during alcoholic fermentation and their role in the metabolic impact and aroma complexity of the final product. Indeed, non- Saccharomyces yeasts may produce high amounts of different metabolites and enzymes able to release aroma compounds from precursors present in grape must (Fernandez et al., 2000). Thus, non- Saccharomyces yeasts may influence the perceivable characteristics of the final product (Romano et al., 2003). In view of the fact that natural fermentations remain uncontrolled processes, several studies have evaluated the possibility of using controlled multistarter cultures to increase the quality of wines. The use of non- Saccharomyces wine yeasts, together with Saccharomyces strains as part of multistarter fermentations, has been proposed as a tool to take advantages of natural fermentation and maintain the control of the fermentative process (Ciani et al., 2006, [Anfang et al., 2009] and [Ciani et al., 2010]). We evaluated the oenological aptitude of non- Saccharomyces wine yeasts belonging to nine different genera. Selected non- Saccharomyces strains with a commercial S. cerevisiae strain were used to set up mixed must microfermentations estimating biomass and fermentation evolution as well as analytical profile of wines. Results of screening allowed to select some non- Saccharomyces yeasts with suitable oenological properties. The comparison between mixed and pure fermentations showed variations in the analytical profiles. The presence and permanence of non- Saccharomyces yeasts during must mixed fermentations positively influence the final product. In particular, yeast interactions frequently allowed the reduction of some negative compounds produced by non- Saccharomyces yeasts such as acetic acid, and the enhancement of favourable aroma compounds (2-phenylethanol, phenylethyl acetate, isoamyl acetate). This work is financed by Consorzio Tuscania, Firenze.

Control of alcoholic fermentation in winemaking: Current situation and prospect

Abstract Winemaking fermentations aim to optimise product quality, which is very difficult to quantify. Control over fermentation kinetics generally has direct technological advantages, in terms of tank use optimisation in the winery and control over energy expenses for the regulation of temperature and is generally a prerequisite for controlling the characteristics of the wine. How new technologies can assist the winemakers to elaborate wines with predefined characteristics and improve process performances as well as hygienic properties? On-line fermentation monitoring is one promising way because: (i) it is much more accurate than manual measurements and (ii) it makes possible new control strategies with an optimal control tank by tank. Later, preventive control, based on modelling of the fermentation process, may be possible. New processes, such as cell immobilisation, may also be used as well as methodologies in the domain of data management and knowledge based systems.

Fermentation alcoolique

The control of alcoholic fermentation is necessary to obtain a quality wine. The overall dynamic and phenomenological modelling already applied to the simulation of this type of reaction enables us to suggest, in this study, a simple model (of which two variants), are relatively satisfactory. The first variant does not take into account the variation of the ambient temperature; the model translates exactly the first phase of the experimental curve or the moment when highest temperatures are measured. The relaxation phase is less well described because of influence of variation of the ambient temperature is relatively important. The second one considers the system depending on the ambient temperature, the model is correct for the relaxation phase too (the reaction temperature decreases, it nears the ambient temperature). The advantage of this model: It permits one to determine the reaction enthalpy and the kinetic parameters.