Yeasts Inoculation Effect on Bacterial Development in Carbonic Maceration Wines Elaboration

Carbonic maceration (CM) vinification is a very traditional method that allows saving energy without great equipment investment, obtaining high-quality wines. However, due to its particularities, CM winemaking implies a higher risk of microbial alteration. This work studies the evolution of bacterial population along carbonic maceration wines elaboration with and without yeast inoculation. In the same way, two strategies of yeast inoculation were studied: "pied de cuve" and Active Dry Yeasts (ADY) seed. For this purpose, three conditions were assayed: spontaneous fermentation (without inoculation), "pied de cuve" technology, and ADY inoculation. For each condition, two winemaking methods were compared: carbonic maceration and the standard method of destemming and crushing (DC). The bacterial evolution (lactic acid and acetic acid bacteria) was followed in different fermentation stages. Finally, the wines obtained were analysed (pH and volatile acidity). In the non-inoculated wines produced by CM, high development of the bacterial population was observed (counts of acetic acid bacteria around 4.3 log cfu/mL), and finished wines presented high values of volatile acidity (>1.5 g/L), which did not occur in the inoculated vinifications (counts of acetic acid bacteria around 1.5 log cfu/mL and 0.5 g/l of volatile acidity). Thus, the control of yeast population, as a "pied de cuve" as ADY seed, seems to be an effective tool to avoid bacterial alterations in CM vinifications.

Carbonic maceration vinification: A tool for wine alcohol reduction

The increase in alcohol content in wine due to climate change is one of the main challenges that winemakers face today. Previous studies have indicated that carbonic maceration processing can be used to obtain a wine fraction with lower alcoholic strength. The aim of this study was to determine the effectiveness of this technique in obtaining wines with lower alcohol content. For this purpose, seven trials were carried out, studying a total of 63 wines. The physico-chemical, phenolic and aromatic composition of the wines was analysed using official methods and gas chromatography. The results showed that it is possible to obtain a fraction of carbonic maceration wine (25-35% of the total) with a reduction in alcohol content of up to almost 4% depending on the vinification conditions and the grape variety used. Therefore, this CM fraction, marketed on its own, could be a low-alcohol alternative to red wines.

Influence of the temperature and the origin of CO2 (anaerobiosis methodology) on the intracellular fermentation of wines made by carbonic maceration

BACKGROUND

The present study aimed to determine the optimal conditions for making wines by the carbonic maceration (CM) method. In this test, we attempted to identify the causes of the higher volatile acidity of some wines vinified by this method. Accordingly, we measured the development and speed of intracellular fermentation inside the whole grapes under different vinification conditions.

RESULTS

An active fermentation of the must in the tanks produced by inoculation with active dry yeasts was more efficient for the process than the addition of exogenous carbon dioxide (CO₂ ). In addition, in CM vinification, the moment of devatting had a great influence on the content of acetaldehyde and acetic acid in the whole grapes.

CONCLUSION

Yeast inoculation in the tanks and control of the devatting time are technological tools that could play an important role in the characteristics of the wines produced by carbonic maceration, especially with respect to acetic acid content. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Ethephon foliar application: Impact on the phenolic and technological Tempranillo grapes maturity

In recent years, there has been increasing concern about the impact of climate change on viticulture, in particular regarding its influence on grape maturity and quality. Extensive research has shown that the rise of temperatures during grape ripening accelerates the accumulation of sugars while reducing the synthesis of phenolic and aromatic compounds. The aim of this study was to investigate whether the foliar application of the plant growth regulator ethephon might delay technological grape maturity and increase grape phenolic content, improving wine quality. For this, different concentrations of ethephon were applied during two vintages to the Tempranillo grape variety at the onset of veraison. Results showed that grape sugar accumulation was delayed in one of the two vintages, whereas the treatment favored the accumulation of phenolic compounds in both vintages. In conclusion, the application of ethephon at the onset of veraison to Tempranillo grapevines helped to couple grape phenolic and technological maturity, leading to more balanced wines, either by delaying sugar accumulation or by enhancing the synthesis of anthocyanins and phenolic compounds. PRACTICAL APPLICATION: Due to the current climate change, phenolic maturity of grapes does not match with their technological maturity, which means that harvested grapes are usually very sweet but without enough color and aroma. The foliar application of the plant growth regulator-ethephon-delays technological grape maturity and increases grape phenolic content, improving wine quality and creating wines that are more balanced.

Influence of the carbonic maceration winemaking method on the physicochemical, colour, aromatic and microbiological features of tempranillo red wines

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. Wines made by carbonic maceration presented higher aromatic quality due to their higher total content of esters and acetates, as well as a greater colour intensity due to a higher phenolic content and higher rates of ionization and polymerization. In addition, it was observed that the antioxidant activity, the content in coumaroyl derivatives of anthocyanins and the vitisins A and B were considerably greater in wines made by carbonic maceration.

Effect of the Sequential Inoculation of Non-Saccharomyces/Saccharomyces on the Anthocyans and Stilbenes Composition of Tempranillo Wines

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-Saccharomyces species were tested because they might enhance the properties of red Tempranillo wines from Rioja. The results confirmed that the anthocyanins and stilbenes composition of wine can be modulated with the use of a specific fermentation starter. Metschnikowia pulcherrima, Zygosaccharomyces bailii, Candida zeylanoides, and Torulaspora delbrueckii achieved the greatest improvements of the monomeric anthocyanin composition, and the latter three yeast species achieved the best results of stilbene composition when compared to S. cerevisiae and the other non-Saccharomyces yeasts. Overall, results suggested that the use of M. pulcherrima, Z. bailii, C. zeylanoides and T. delbrueckii as fermentation starters could be of great interest to achieve wines with better color and likely healthy properties.

Evaluating a preventive biological control agent applied on grapevines against Botrytis cinerea and its influence on winemaking

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. Data showed that general grape quality and spontaneous alcoholic fermentation performance were not influenced by either fungicide application. The chemical fungicide had a considerable influence on the clonal diversity of Saccharomyces cerevisiae species, which led to the alcoholic fermentation. Furthermore, it caused longer malolactic fermentation than with the biological fungicide and in the control. The biofungicide made malolactic fermentation 1 day shorter because the establishment of the commercial lactic acid bacteria used as a starter culture was total. After malolactic fermentation, the wines did not show significant differences in general oenological parameters.

CONCLUSION

Preventive biofungicide treatment against B. cinerea did not negatively influence the quality of grapes and wines and the fermentation processes. Therefore, biological control of B. cinerea with B. subtilis applied on grapevines could be advisable in oenological terms. © 2018 Society of Chemical Industry.

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

AIMS

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.

METHODS AND RESULTS

Pure cultures were inoculated in pasteurized grape juice in order to perform alcoholic fermentations. Some non-Saccharomyces species did not ferment, others did not get established and none of them completed alcoholic fermentations. The physico-chemical parameters of the wines and the abundance of aromatic compounds at the end of alcoholic fermentation highlighted the notable differences in the aroma-forming ability and fermentative behaviour of the different non-Saccharomyces species, but not within clones.

CONCLUSIONS

Lower diversity was detected within non-Saccharomyces species than that reported in S. cerevisiae with regard to enological behaviour and aromatic profiles. Metschnikowia pulcherrima and L. thermotolerans are the two species with higher possibilities to become an inoculum.

SIGNIFICANCE AND IMPACT OF THE STUDY

Few significant differences were found within clones of the same species, but very important parameters in wine quality, such as volatile acidity, ethyl acetate and acetoin, which would justify selection programmes within those species. The results also demonstrated that T. delbrueckii and L. thermotolerans are two close species in their aromatic profiles.

Screening of enzymatic activities within different enological non-Saccharomyces yeasts

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.

Genetic and phenotypic intraspecific variability of non-Saccharomyces yeasts populations from La Rioja winegrowing region (Spain)

AIMS

To determine the intraspecific genetic diversity within five non-Saccharomyces yeast species and the diversity in phenotypic characteristic related to their technological properties.

METHODS AND RESULTS

Seventy-one non-Saccharomyces yeasts isolated from different fermentations and facilities of the DOCa Rioja (Spain) belonging to five different wine species (Torulaspora delbrueckii, Lachancea thermotolerans, Metschnikowia pulcherrima, Zygosaccharomyces bailii and Williopsis pratensis) were subjected to clonal characterization by RAPD-PCR, which evidenced wide diversity between them. They were also submitted to a screening for some oenological traits related to the improvement of the aroma of the wine and yeast development in musts. Strains within the same species showed different enzyme activities, tolerated different levels of SO₂ and possessed different killer phenotypes. These characteristics made them adjust better or worse to specific vinification processes or wine quality criteria.

CONCLUSIONS

A significant genetic and phenotypic variation within the non-Saccharomyces species studied was found, which makes necessary to carry out a selection process in each one.

SIGNIFICANCE AND IMPACT OF THE STUDY

Williopsis pratensis, a species that has not been thoroughly explored, may deserve further consideration for oenological applications. Due to the wide range of variation within species, the strains adaptation to the SO₂ levels in musts has to be taken into account in selection processes.

Factors of influence in the distribution of mold in the air in a wine cellar

This paper studies the presence of mold in the air of a vinification and ageing wine cellar. The influence of other factors such as the time of year, the sampling point, and the activity being carried out in the cellar has been analyzed. Neither the type of activity being carried out in the cellar nor the temperature or relative humidity fluctuations throughout the year are determining factors in the presence of mold in the air. For this group of microorganisms, the design of the cellar studied is the fundamental factor. Areas with little ventilation favor high levels of relative humidity and, hence, a higher presence of mold in the air. The mold population in these areas is not very diverse, which indicates that colonization by certain types of mold that have adapted to the conditions established therein is permanent. Areas with greater air flow, constant activity, and frequent cleaning show lower mold populations in the air and of a more varied composition.

PRACTICAL APPLICATION

  This work shows that given the growing importance of the presence of mold in wine cellars, the design thereof should take into account suitable ventilation of all the areas and control of the relative humidity. Hence, the presence of traditional underground areas for ageing wine, which is justifiable in seasons where temperature and humidity control lead to major technical problems, should be reconsidered in the design of new wine cellars.

Presence of non-Saccharomyces yeasts in cellar equipment and grape juice during harvest time

The purpose of this study was to analyze the presence of different yeasts in the facilities of four wineries from the D.O.Ca. Rioja region in Spain. The study was conducted through the identification of the yeasts via the PCR-RFLP technique of the ITS region of rDNA. The diversity of non-Saccharomyces yeasts found in wineries has previously only been studied to a limited extent, despite the fact that these yeasts take part both in the start of spontaneous fermentation and in the changes which occur in the wines during their subsequent conservation. Most earlier studies carried out on cellar ecosystems have focussed on the clonal diversity of Saccharomyces cerevisiae. The results obtained in this study indicated that the presence of non-Saccharomyces yeasts in facilities is higher than that of the S. cerevisiae, with percentages of over 60% in all the wineries analyzed. Yeasts belonging to 10 genera and 18 species were isolated, but the only genera present in all four wineries were Cryptococcus, Pichia, and Saccharomyces. The Zygosaccharomyces bailii yeast responsible for taint was detected in one cleaned winery, in both the winemaking equipment and the fermenting must. It was also noted that the quantity and type of yeasts present in the facilities are related to the product used for cleaning them. It is also necessary to point out that the cleaning of the cellars prior to the reception of the grapes does not completely eliminate the yeasts present, so that these can subsequently become part of the vinification process.

Evaluation of lysozyme to control vinification process and histamine production in Rioja wines

Lysozyme and the reduction of metabisulfite addition to red wine were evaluated during a winemaking process and after malolactic fermentation (MLF). Treatment, with lysozyme, of the must from Tempranillo grapes and at the end of alcoholic fermentation (AF) caused the 100% implantation of the inoculated bacterial strain and shortened the duration of MLF by 7 days. At the end of the MLF, wines treated with lysozyme showed lower volatile acidity, color intensity, and biogenic amine content. The differences in color intensity disappeared during wine stabilization. The lysozyme addition after MLF led to lower histamine concentrations in wines. These phenomena occurred irrespective of the lactic acid bacteria (LAB) proliferation control and of the Oenococcus oeni dominant strain identified at this period. The results of this study show the significance of preventive use of lysozyme in vinification of red wine to maintain low histamine levels and ensure a successful implantation of inoculated Oenococcus oeni starters.

Presence of lactic bacteria in the air of a winery during the vinification period

In this paper we have studied the presence and evolution in the winery air of the lactic bacteria responsible for malolactic fermentation. Sampling took place during the winemaking process (between September 2007 and July 2008) in a winery from the Rioja appellation in Spain. The results obtained indicated that the presence of these microorganisms in the atmosphere was detected when grapes were entering the winery, while malolactic fermentation was taking place, and when liquid containing bacteria was manipulated. The species and clones of the lactic bacteria identified were also related to those present in the vinification tanks at any given stage of the process.

The occurrence of fungi, yeasts and bacteria in the air of a Spanish winery during vintage

This research studies the presence of microorganisms of enological interest (yeasts, bacteria and molds) and their evolution in the air of a wine cellar. The samples were taken throughout the winemaking campaign (September-December) in a winery of the D.O.Ca. Rioja, Spain. They were collected using an airIDEAL atmosphere sampler from Biomerieux. For the isolation, specific selective media were used for each group of microorganisms. The results obtained indicate that the presence in the winery air of the various different microorganisms studied is directly related to the winemaking processes that are taking place in the winery. Thus, the number of molds present decreases once grapes have ceased to be brought into the winery. The maximum number of yeasts in the air is found when all the vats in the cellar are fermenting, while the lactic bacteria are not detected until the first malolactic fermentation begins. The species of yeasts and molds identified are also related to the winemaking processes. The coincidence of strains of Saccharomyces cerevisiae among those present in the vats during alcoholic fermentation and those isolated from the air, confirms the role of the latter as a transmitter of microorganisms.

Effect of the addition of inert cellulose substrates to grape must on Saccharomyces cerevisiae diversity and the evolution of alcoholic fermentation

AIMS

To study the addition of cellulose-based adjuvant as a resource to offset the negative effects produced by grape juice clarification during alcoholic fermentations.

METHODS AND RESULTS

The effect of the addition of two kinds of inert cellulose substrates in white wine vinification was investigated in two different musts. In one of these musts, stuck fermentations were detected. One of the types of cellulose examined had a fining effect, which caused a decrease in the number of viable yeasts in the medium and altered the distribution and frequency of the clones, which performed the fermentation. The other cellulose substrate made the medium cloudier but did not alter the distribution of yeasts in comparison with the control.

CONCLUSIONS

The behaviour of the inert cellulose substrates on vinification depends on its physical characteristics and its capacity for making the must cloudy.

SIGNIFICANCE AND IMPACT OF THE STUDY

The addition of inert cellulose substrates in white wine vinification improves the fermentation process and the quality of wines obtained. This effect is more noticeable in difficult fermentations. One variety of cellulose showed an inhibitory effect on Torulaspora delbrueckii yeasts.

Analysis of yeast population during spontaneous alcoholic fermentation: effect of the age of the cellar and the practice of inoculation

An ecological study of spontaneous fermentation in red wine carried out in two wineries located in the same village of the D.O.Ca. Rioja appellation (Spain). These two wineries were very different: one was very old and the other commenced its operations with the 2000 vintage. The study was conducted over seven consecutive years (1997-2003); the first 3 years in the old winery; and the other 4 years in the new one. Another difference between the wineries was the use of commercial strains: no starters were ever used in the old winery and two known strains (A and B) were employed only in a white must vat in the new winery. The number of different Saccharomyces cerevisiae strains detected for each vintage and the frequency of their appearance varied between the old winery and the new winery. There was no one clearly dominant clone in the fermentations studied in the old winery, whereas in the vinifications monitored in the new winery, a clear majority strain was detected. The same S. cerevisiae clone took over the spontaneous fermentation of all the vintages studied in this new winery. Analysis of the mtDNA restriction pattern of this strain revealed that it was identical to one of the commercial strain used (starter A), despite the fact that the fermentation studied was spontaneous. Microbial analysis conducted on winery equipment and winery surfaces prior to the 2003 vintage revealed that starter A had become a resident of the winery with a percentage of 50% among all S. cerevisiae. The presence of non-Saccharomyces yeasts in the early stages of vinification also differed between the old and new wineries.