Wine-making Process Research Articles

A new two-phase passive temperature control system for a wine fermenter

Thermal control of a fermenter tank is fundamental to guarantee a high-quality final product, especially in wine-making processes. Indeed, temperature is a crucial parameter for alcoholic fermentation in the production of wine, since it could modulate the generation of secondary products of fermentation in specific aromatic compounds. Fermentation is an exothermic process, and an efficient refrigeration system in fermenter tanks is necessary. Usually, to achieve this aim in fermentation tanks for wine-making processes, an external shell is implemented where a cooling fluid, normally water, flows. The circulation of the service fluid is triggered only when the temperature in the fermenter overcomes a critical value; however, this classical system could generate oscillation and stratification of the must temperature, reducing the goodness of the fermentation process. In this work, a substitutive cooling system based on heat pipe technology is proposed, and its feasibility is studied. It presents the benefit of always working and, for this reason, keeping a more constant and uniform value of temperature in the fermenter for the entire process duration. Additionally, the presented solution is completely passive, lowering energetic and economical costs. The obtained outcomes proved that the practical adoption of the proposed cooling system is achievable and that it constitutes an encouraging option.

Impact of fermentation-temperature management combined with specific yeast choice on energy savings in white winemaking

Heat removal significantly impacts energy request in the winery and is related to the temperature control of wine tanks during the fermentation process and the wine maturation phase. The aim of this work was twin: first, to determine the heat dissipated from tanks under different temperature fermentation programs, to evaluate the impact of temperature management combined with specific yeast choice on energy saving during industrial-scale (450 hL) white vinification. Second, to explore the applicability of such protocols, and the extent of the potential effects thereof, through a survey. Comparative winemaking tests were carried out by using properly chosen yeasts during fermentation of Glera and Pinot Grigio musts at usual winery temperature (15 or 17-15 °C) and 19 °C, verifying the quality of the resulting wines in term of sensory, chemical and aromatic features. Fermentation required on average 7.0 Wh dm-3 at 19 °C and 10.3 Wh dm-3 must at 15/17-15 °C, reducing energy use by ~32% at the higher temperature, without compromising sensory, chemical, and aromatic profiles of wines. Then, the potential widespread of those effects was investigated through a survey involving several (n>100) wineries: among others, questions about vinification volumes, usual fermentation temperatures and attitude towards energy-saving innovations were asked to winemakers. Our results suggest that wineries can adopt a more sustainable winemaking process with low energy consumption and that this choice may have a relevant impact on white-winemaking energy consumption in the Italian context. Indeed, ~70% of a sample of winemakers representing an overall production of 1.300.000 hL, declared a willingness to increase their usual fermentation temperature if research data support energy-saving expectations without compromising wine quality.

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.

Stereoselective behavior and residues of the imazalil during strawberry growth and strawberry wine production

Imazalil is a chiral fungicide widely used to protect strawberries against gray mold, which may pose threats to food safety. This study aims to investigate the stereoselective behavior of imazalil during strawberry growth and strawberry wine production. A method was proposed and validated for the extraction and quantitative analysis of imazalil residues in strawberry, strawberry pomace, and strawberry wine by using ultra-high performance liquid chromatography-tandem mass spectrometry. The method exhibited mean recoveries ranging from 86.2% to 119.7% with relative standard deviations of 0.1–11.3%. The dissipation curve of imazalil during strawberry growth followed the first-order kinetic model with a half-life ranging from 6.5 to 7.1 days. Significant enantioselectivity of imazalil was observed in strawberry grown under field conditions and strawberry wine production process, with enantiomeric fraction values ranging from 0.51 (2 h) to 0.42 (27d) and from 0.48 (0d) to 0.52 (10d), respectively. (+)-imazalil was preferentially degraded in strawberry under field conditions, while (−)-imazalil was preferentially degraded during the fermentation process. The processing factor was lower than 1 for each procedure, indicating that the wine-making process can reduce imazalil residue in strawberry. These findings may facilitate a more accurate risk assessment of imazalil and provide important guidance for the safe and efficacious use of imazalil in agriculture.

Morula Tree: From Fruit to Wine through Spontaneous Fermentation and the Potential of Deriving Other Value-Added Products

Sclerocarya birrea (Morula tree) is one of the indigenous trees bearing wild fruits with various applications in the African communities. Wine is a globally known beverage usually made from grapes; however, recently, other fruits, including wild fruits with a considerable amount of sugars, can be used for making wines. The marula fruit wine is also important in many communities for cultural activities and can be enjoyed by people of varying age groups depending on the age of the product. In recent years, there has been growing interest in shifting from traditional marula winemaking to developing technologies for the marula winemaking process and commercialisation. The process of marula winemaking is similar to the production of grape wines, which entails collection, selection and washing of the fruits; extraction of the juice and mashing; formation and removal of the scum; and ultimately spontaneous fermentation of the resulting juice. The new process in marula winemaking would take into consideration the use of starter cultures as either monoculture or mixed cultures developed from the native marula fruit microbiota and the pasteurisation of the juice. The main challenge or difficulty with marula is the extraction of sugar and other soluble solids from the pulp more than it is for the grapes. The other challenge confronting the sustainability of marula wine is the seasonality of the fruit and poor juice yield. It is therefore imperative to develop strategies to increase the juice yield without affecting the quality, to preserve the marula fruits to ensure the year-round presence of marula fruit wine in the markets and, consequently, to improve the income generation capacity of the households dependent on the product. In addition to achieving a high juice yield, it is imperative to ensure consistent quality wine products. This review gives an overview of the S. birrea subsp. caffra and the biochemical components of the fruits or juice. It also highlights the use of marula fruits for wine production in African communities. The potential economic sustainability of the marula fruit wine is explored, particularly in southern Africa, where the marula tree (Morula) is abundant and the marula fruit wine is popularly produced. The review also examines the opportunities, challenges and future prospects of the marula fruit wine.

Combining Different Approaches for Grape Pomace Valorization: Polyphenols Extraction and Composting of the Exhausted Biomass

Grape pomace represents 60%, by weight, of the solid side-streams of the wine-making process. The quantities produced, seasonality, and the presence of polyphenols pose economic and environmental issues that require proper management approaches based on the principles of sustainability and circular economy. The present work focuses on the combined application of solid–liquid extraction of polyphenols from ground grape pomace using a hydroethanolic mixture and the composting of the exhausted pomace. The obtained results support the possibility of recovering approximately 76.5 g of extract per kg of dry grape pomace (or 1.8 g of total phenols per kg of dry grape pomace). The composting process was not affected by the extraction process. On the contrary, the composting process was enhanced by the pomace particle size reduction, in terms of final biostability and content of humic acids.

Dissipation behavior of prochloraz and its metabolites in grape under open-field, storage and the wine-making process

The fate of prochloraz and its four metabolites (BTS44595, BTS44596, BTS40348 and BTS45186) in grape under field (pre-harvest) and post-harvest conditions (storage at 4 °C) during 28 days and after wine-making process were studied. The prochloraz and its four metabolites were separated and determined using a modified QuEChERS method with high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). The matrix-matched calibrations were constructed for grape, wine and pomace, and the correlation coefficients (R2) exceeded 0.9921. Acceptable recoveries (77.5–105.4%) were acquired with RSDs less than 13.1%. Field and storage results showed that the half-lives of prochloraz were 10.15–11.95 and 20.38–24.75 days, respectively. The results indicated that the processing factors (PFs) of each procedure (washing, peeling, fermentation and clarification) were less than 1, and the PFs of the overall process ranged from 0.03 to 0.19, which suggested that the wine-making process can reduce the prochloraz and its metabolites residues. The results from this study presented reliable references for understanding the fate of prochloraz and its metabolites in grape, and also provided valuable information for the risk assessments of prochloraz and its metabolites during the wine-making process.

Effect of added sulphur dioxide levels on the aroma characteristics of wines from Panciu wine region

In the wine-making process, the yeasts form over 20 higher alcohols that improve the sensation of palatine veil for the wine. The amount of higher alcohols is lower for white and rosé wines obtained from clarified musts fermented at moderate temperatures. The formation of higher alcohols is confirmed by the fact that the addition of certain nitrogen compounds to a glucose-containing culture medium leads, after the fermentation, to an increase in the higher alcohol content. Data evaluate by comparison the levels of higher alcohols, esters and aldehydes, important to fermentation process in case of several wines from Panciu region. The wine-making was done by classical methods and by using specific protocols for low content sulphur dioxide. This study is focused to compare wines obtained from two grape varieties produced at industrial level: Feteasca regala vs. Feteasca regala Frizzante and Cabernet Sauvignon rosé vs. Cabernet Sauvignon. The compounds were analyzed by GC-FID method with head-space technique for methanol, 1-propanol, 2-methyl-propanol, 1-butanol, ethyl acetate, ethyl lactate, isoamyl acetate and acetaldehyde. The results showed that in almost every comparative study the levels of aroma compounds are maintained, when compared with the wines with low content of sulphur dioxide. Tuckey test showed that 1-propanol and ethyl acetate register statistically significant differences for Cabernet Sauvignon rosé and for Feteasca regala Frizzante.

The Cdc25/Ras/cAMP-dependent protein kinase A signaling pathway regulates proline utilization in wine yeast Saccharomyces cerevisiae under a wine fermentation model.

Proline is a predominant amino acid in grape must, but it is poorly utilized by the yeast Saccharomyces cerevisiae in wine-making processes. This sometimes leads to a nitrogen deficiency during fermentation and proline accumulation in wine. In this study, we clarified that a glucose response is involved in an inhibitory mechanism of proline utilization in yeast. Our genetic screen showed that strains with a loss-of-function mutation on the CDC25 gene can utilize proline even under fermentation conditions. Cdc25 is a regulator of the glucose response consisting of the Ras/cAMP-dependent protein kinase A (PKA) pathway. Moreover, we found that activation of the Ras/PKA pathway is necessary for the inhibitory mechanism of proline utilization. The present data revealed that crosstalk exists between the carbon and proline metabolisms. Our study could hold promise for the development of wine yeast strains that can efficiently assimilate proline during the fermentation processes.

Combination of Pulsed Electric Field and Ultrasound in the Extraction of Polyphenols and Volatile Compounds from Grape Stems

Increasing the yield of extraction of bioactive compounds from plants is of high importance. Grape stems are widely discarded during the wine-making process, despite their high content in many valuable compounds. The aim of this work was to examine whether the use of pulsed electric field (PEF) treatment of the stems could increase the yield of polyphenol and volatile compounds in the extracts. For this reason, a relatively low-energy consuming PEF process was employed (low-electric field strength, 1 kV/cm) for a short time (30 min) at the grape stems. In addition, the effect of different solvents during this pretreatment step was examined. With the use of Folin–Ciocalteu assay, the extracts were compared with the respective control samples (not pretreated with PEF). Moreover, extracts were prepared to assess whether changes occur to the volatile profile of the extracts. The results were conclusive that not only PEF can increase the yield of polyphenols (up to 35% increase recorded), but also that the solvent used during PEF pretreatment can affect the process. Furthermore, a 234% increase in the total content of volatile compounds was recorded, when PEF was used as a pretreatment step. Therefore, the combination of PEF and ultrasound-assisted extraction is highly promising to obtain grape stem extracts with a higher content of bioactive compounds.

Trials of Commercial- and Wild-Type Saccharomyces cerevisiae Strains under Aerobic and Microaerophilic/Anaerobic Conditions: Ethanol Production and Must Fermentation from Grapes of Santorini (Greece) Native Varieties

In modern wine-making technology, there is an increasing concern in relation to the preservation of the biodiversity, and the employment of “new”, “novel” and wild-type Saccharomyces cerevisiae strains as cell factories amenable for the production of wines that are not “homogenous”, expressing their terroir and presenting interesting and “local” sensory characteristics. Under this approach, in the current study, several wild-type Saccharomyces cerevisiae yeast strains (LMBF Y-10, Y-25, Y-35 and Y-54), priorly isolated from wine and grape origin, selected from the private culture collection of the Agricultural University of Athens, were tested regarding their biochemical behavior on glucose-based (initial concentrations ca 100 and 200 g/L) shake-flask experiments. The wild yeast strains were compared with commercial yeast strains (viz. Symphony, Cross X and Passion Fruit) in the same conditions. All selected strains rapidly assimilated glucose from the medium converting it into ethanol in good rates, despite the imposed aerobic conditions. Concerning the wild strains, the best results were achieved for the strain LMBF Y-54 in which maximum ethanol production (EtOHmax) up to 68 g/L, with simultaneous ethanol yield on sugar consumed = 0.38 g/g were recorded. Other wild strains tested (LMBF Y-10, Y-25 and Y-35) achieved lower ethanol production (up to ≈47 g/L). Regarding the commercial strains, the highest ethanol concentration was achieved by S. cerevisiae Passion Fruit (EtOHmax = 91.1 g/L, yield = 0.45 g/g). Subsequently, the “novel” strain that presented the best technological characteristics regards its sugar consumption and alcohol production properties (viz. LMBF Y-54) and the commercial strain that equally presented the best previously mentioned technological characteristics (viz. Passion Fruit) were further selected for the wine-making process. The selected must originated from red and white grapes (Assyrtiko and Mavrotragano, Santorini Island; Greece) and fermentation was performed under wine-making conditions showing high yields for both strains (EtOHmax = 98–106 g/L, ethanol yield = 0.47–0.50 g/g), demonstrating the production efficiency under microaerophilic/anaerobic conditions. Molecular identification by rep-PCR carried out throughout fermentations verified that each inoculated yeast was the one that dominated during the whole bioprocess. The aromatic compounds of the produced wines were qualitatively analyzed at the end of the processes. The results highlight the optimum technological characteristics of the selected “new” wild strain (S. cerevisiae LMBF Y-54), verifying its suitability for wine production while posing great potential for future industrial applications.

Evaluation of plant protection efficacy in field conditions and side effects of Lysobacter capsici AZ78, a biocontrol agent of Plasmopara viticola

ABSTRACT Downy mildew, caused by Plasmopara viticola, is a highly significant grapevine disease causing severe yield losses and affecting wine quality. Disease control mainly relies on use of copper and synthetic fungicides. Today there is a growing interest in developing microbial biopesticides for downy mildew control in integrated and organic viticulture. Here, the bacterial biocontrol agent Lysobacter capsici AZ78 (AZ78) was tested following a holistic approach including in planta efficacy test (large-scale trial) combined with bioassays aiming to assess potential adverse effects on non-target organisms: beneficial arthropods (Aphidius rhopalosiphi and Typhlodromus pyri), the crustacean Daphnia magna, the algae Selenastrum capricornutum and soil organisms [earthworm Eisenia (Ei.) fetida and worm Enchytraeid (En.) albidus]. Moreover, side effects of AZ78 treatments on grape quality and wine-making process were assessed. The results showed that AZ78 was equally effective to reference fungicide (Kocide®2000) in controlling downy mildew on leaves and bunches. AZ78 had no significant effect on the mortality of the indicator arthropod species at a Limit test Rate, which was equal to four times the recommended field rate. Additionally, no significant effects (mortality, growth rate or reproduction) were observed on D. magna, Ei. albidus, En. fetida and S. capricornutum, indicating AZ78 low toxicity on non-target organisms. Likewise, the yeast population dynamics in fermenting musts was not affected, without compromising the fermentation processes and wine quality. Overall, this study provides new insights into the characterisation of the biocontrol agent AZ78 showing that this bacterium has the potential to be further developed as a commercial biopesticide.

The fate of thiamethoxam and its main metabolite clothianidin in peaches and the wine-making process

Thiamethoxam is widely used to control a large number of insect pests of peach crops. Understanding the fate of thiamethoxam and its main metabolite clothianidin in field peach, during storage, and in the processing of peach wine is of vital importance for food safety. The thiamethoxam and clothianidin were separated and determined by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS). Field and storage results showed that the half-lives of thiamethoxam were 4.9–5.5 and 10.3–15.8 days, respectively. The processing factors (PFs) of all the wine-making procedures were less than 1, and the PFs of the overall process ranged from 0.10 to 0.47. The highest elimination rate was obtained for thiamethoxam and clothianidin during the fermentation process. The results from this study could understand the dissipation kinetics and residual levels of thiamethoxam and clothianidin in peach, and also help to accurately assess their risks in the raw and wine-making process.

LC-MS-Based Metabolomics Discriminates Premium from Standard Chilean cv. Cabernet Sauvignon Wines from Different Valleys.

Cabernet Sauvignon grapes in Chile, mainly grown between the 30° S and 36° S, account for more than 30% of Chilean wine production, and yield wines with different characteristics which influence their quality. The aim of this study was to apply a liquid chromatography – mass spectrometry (LC–MS)-based metabolomic protocol to investigate the quality differentiation in a sample set of monovarietal wines from eight valleys covering 679 km of the north-south extension. All samples were produced using a standardized red winemaking process and classified according to a company categorization in two major groups: premium and standard, and each group in two subcategories. The results pointed out that N-containing metabolites (mainly small peptides) are promising biomarkers for quality differentiation. Moreover, the premium wines were characterized by higher amounts of anthocyanins and other glycosylated and acetylated flavonoids, as well as phenolic acids; standard quality wines, on the other hand, presented stilbenoids and sulfonated catabolites of tryptophan and flavanols.

Multi-Sensor Characterization of Sparkling Wines Based on Data Fusion

This paper is focused on the assessment of a multi-sensor approach to improve the overall characterization of sparkling wines (cava wines). Multi-sensor, low-level data fusion can provide more comprehensive and more accurate vision of results compared with the study of simpler data sets from individual techniques. Data from different instrumental platforms were combined in an enriched matrix, integrating information from spectroscopic (UV/Vis and FTIR), chromatographic, and other techniques. Sparkling wines belonging to different classes, which differed in the grape varieties, coupages, and wine-making processes, were analyzed to determine organic acids (e.g., tartaric, lactic, malic, and acetic acids), pH, total acidity, polyphenols, total antioxidant capacity, ethanol, or reducing sugars. The resulting compositional values were treated chemometrically for a more efficient recovery of the underlaying information. In this regard, exploratory methods such as principal component analysis showed that phenolic compounds were dependent on varietal and blending issues while organic acids were more affected by fermentation features. The analysis of the multi-sensor data set provided a more comprehensive description of cavas according to grape classes, blends, and vinification processes. Hierarchical Cluster Analysis (HCA) allowed specific groups of samples to be distinguished, featuring malolactic fermentation and the chardonnay and red grape classes. Partial Least Squares-Discriminant Analysis (PLS-DA) also classified samples according to the type of grape varieties and fermentations. Bar charts and complementary statistic test were performed to better define the differences among the studied samples based on the most significant markers of each cava wine type. As a conclusion, catechin, gallic, gentisic, caftaric, caffeic, malic, and lactic acids were the most remarkable descriptors that contributed to their discrimination based on varietal, blending, and oenological factors.

Influence of Oak Chips and Oak Barrel Ageing on Volatile Profile in Chardonnay Wine of Romania

The influence of the addition of oak chips and barrel ageing on basic wine parameters and volatile compounds of Chardonnay wines has been studied. Chardonnay wines were obtained by the traditional wine-making process. Oak chips (4 g/L—non-toasted and light toasted) were added at the final stage of the winemaking process for ageing 1, 2 and 3 months, respectively. Also, the control wine was aged in non-toasted barrels for the same period of time. Following Liquid-liquid extraction-gas chromatography-mass spectrometry analysis, alcohols, esters, fatty acids, lactones, and phenolic compounds were identified and quantified. The light toasted wine was clearly separated by phenolic compounds (vanillin, p-vinyl guaiacol and acetovanillone). The floral aroma supplied by 2-phenylethanol was slowly increased by ageing with odor activity values (OAV) higher in aged samples than control wine (1.07). The vanilla scent could be easily perceived in all aged samples, mainly for light toasted chip-treated samples with OAV values between 2.30 and 2.37. After 3 months, the volatile compounds of wine from non-toasted medium (chips and barrels) were almost similar from the volatile profile point of view. This could have economic and vinification management implications since oak barrels are expensive and the wine oak barrel aging is a long process. All wines studied in this research can provide a viable alternative to young varietal wines.

THE EFFECT OF DIFFERENT TECHNIQUES OF MACERATION-FERMENTATION ON THE PHENOLIC COMPOSITION OF RED WINES

Grapes, the quintessential quality factor in winemaking, are found in certain areas of the globe where viticulture thrives. The quality of wine products is directly influenced by the quality of the grapes, their process technology, the care and the quality of the premises and equipment used, as well as the conditions for the storage and use of the wines. In most red wine-making processes, it is preferred that the maceration process is accompanied by the fermentation process, as increase in the alcohol content favours the intensification of the extraction process. For this reason, both processes are combined in a single technological operation known as maceration-fermentation. The largest amount of polyphenolic compounds of wine, anthocyanins and tannins comes from the solid parts of the grapes - the skins and seeds, and these have a decisive influence on the phenolic character of wines. Maceration is a fractional extraction which leads to the dissolution of the useful components of the grapes, which give the flavour, colour and taste typical of red wine. The aim of this research was to analyse the effect of different techniques of maceration fermentation on the phenolic composition of red wines obtained from Merlot, Pinot noir and Cabernet Sauvignon grape varieties in Copou-Iasi vineyard compared to red wines obtained from the same varieties in Murfaltar vineyard, located in the northeast and south of Romania, respectively. Wines obtained by maceration-fermentation in rotating tanks have higher values of the Folin-Ciocâlteu index (wines obtained from Pinot noir) in contrast to those obtained by the classical maceration-fermentation technique (wines obtained from Merlot and Cabernet Sauvignon).

Monitoring the behavior of imazalil and its metabolite in grapes, apples, and the processing of fruit wine at enantiomeric level.

Imazalil is widely used in agriculture, which may pose a threat to food safety. This study aimed to investigate the fate of imazalil and its main metabolite, R14821 (imazalil-M), in field grapes and apples, and in the processing of fruit wine at the enantiomeric level. Analysis method was established to determine imazalil and imazalil-M enantiomers in grape, apple, fruit wine and pomace. The method showed acceptable recoveries of 71.6-99.9% and precision with relative standard deviation of 0.3-11.7%. Processing factors (PFs) were 0.15-0.40 (for imazalil enantiomers) and <0.13-0.83 (for imazalil-M enantiomers) during the wine-making process. The PFs after individual steps including washing, peeling, fermentation, and clarification were all less than 1. No enantioselective dissipation of imazalil was found in grapes under field conditions with half-lives of 23.82-24.49 days. R-(-)-imazalil degraded slightly faster than S-(+)-imazalil in apples under field conditions with half-lives of 9.82-10.09 days. S-(+)-imazalil-M preferentially degraded in field grapes and apple. No significant enantioselectivity of imazalil and imazalil-M was observed during the wine-making process. The enantiomeric fraction (EF) values of imazalil were 0.484-0.511 and 0.509-0.522 in grape wine and cider, respectively. The EFs were 0.484-0.501(in grape wine) and 0.484-0.504 (in cider) for imazalil-M. The results showed that the wine-making process could reduce imazalil and imazalil-M residues in grapes and apples. The finding of non-enantioselectivity of imazalil during the processing of fruit wine was useful for accurate risk assessment for imazalil in raw and processing fruits. © 2021 Society of Chemical Industry.

Population Dynamics and Yeast Diversity in Early Winemaking Stages without Sulfites Revealed by Three Complementary Approaches

Nowadays, the use of sulfur dioxide (SO2) during the winemaking process is a controversial societal issue. In order to reduce its use, various alternatives are emerging, in particular bioprotection by adding yeasts, with different impacts on yeast microbiota in early winemaking stages. In this study, quantitative-PCR and metabarcoding high-throughput sequencing (HTS) were combined with MALDI-TOF-MS to monitor yeast population dynamic and diversity in the early stages of red winemaking process without sulfites and with bioprotection by Torulaspora delbrueckii and Metschnikowia pulcherrima addition. By using standard procedures for yeast protein extraction and a laboratory-specific database of wine yeasts, identification at species level of 95% of the isolates was successfully achieved by MALDI-TOF-MS, thus confirming that it is a promising method for wine yeast identification. The different approaches confirmed the implantation and the niche occupation of bioprotection leading to the decrease of fungal communities (HTS) and Hanseniaspora uvarum cultivable population (MALDI-TOF MS). Yeast and fungi diversity was impacted by stage of maceration and, to a lesser extent, by bioprotection and SO2, resulting in a modification of the nature and abundance of the operational taxonomic units (OTUs) diversity.

Ullage level monitoring model using sensors inside and outside the system in the fino-style winemaking aging process

Manual control of wine production possibly can be ineffective, considering in a winery there could be more than one parameter quality control with many tanks or barrels produced at the same time. In the aging process of Fino-style winemaking, the ullage must be maintained at a constant level. Considering the existing barrels and tanks, space is needed to place the sensor to collect data with the best result possible. In the case of sensor placement inside the system, an ultrasonic sensor is used by acquiring the time data needed to receive the signal emitted from the sensor. Whereas in the case of sensor placement outside the system, a microphone is being used to acquire sound frequency data generated from hitting wine cask with solenoids in a sample time of 100ms. Based on the latest research, the two sensors can be used to acquire ullage data from casks. However, for long-term use of an ullage monitoring system, it is recommended to use the inside one, although it is more expensive, the simple working principle and easier maintenance making it unlikely to hire experts only for dealing with the sensor nodes.