Fermentation Of Grape Research Articles

Whole genome sequencing of Canadian Saccharomyces cerevisiae strains isolated from spontaneous wine fermentations reveals a new Pacific West Coast Wine clade.

Vineyards in wine regions around the world are reservoirs of yeast with oenological potential. Saccharomyces cerevisiae ferments grape sugars to ethanol and generates flavor and aroma compounds in wine. Wineries place a high-value on identifying yeast native to their region to develop a region-specific wine program. Commercial wine strains are genetically very similar due to a population bottleneck and in-breeding compared to the diversity of S. cerevisiae from the wild and other industrial processes. We have isolated and microsatellite-typed hundreds of S. cerevisiae strains from spontaneous fermentations of grapes from the Okanagan Valley wine region in British Columbia, Canada. We chose 75 S. cerevisiae strains, based on our microsatellite clustering data, for whole genome sequencing using Illumina paired-end reads. Phylogenetic analysis shows that British Columbian S. cerevisiae strains cluster into 4 clades: Wine/European, Transpacific Oak, Beer 1/Mixed Origin, and a new clade that we have designated as Pacific West Coast Wine. The Pacific West Coast Wine clade has high nucleotide diversity and shares genomic characteristics with wild North American oak strains but also has gene flow from Wine/European and Ecuadorian clades. We analyzed gene copy number variations to find evidence of domestication and found that strains in the Wine/European and Pacific West Coast Wine clades have gene copy number variation reflective of adaptations to the wine-making environment. The "wine circle/Region B", a cluster of 5 genes acquired by horizontal gene transfer into the genome of commercial wine strains is also present in the majority of the British Columbian strains in the Wine/European clade but in a minority of the Pacific West Coast Wine clade strains. Previous studies have shown that S. cerevisiae strains isolated from Mediterranean Oak trees may be the living ancestors of European wine yeast strains. This study is the first to isolate S. cerevisiae strains with genetic similarity to nonvineyard North American Oak strains from spontaneous wine fermentations.

Screening of Saccharomyces cerevisiae and Torulaspora delbrueckii strains in relation to their effect on malolactic fermentation.

The use of Torulaspora delbrueckii in the alcoholic fermentation (AF) of grape must is increasingly studied and used in the wine industry. In addition to the organoleptic improvement of wines, the synergy of this yeast species with the lactic acid bacterium Oenococcus oeni is an interesting field of study. In this work, 60 strain combinations were compared: 3 strains of Saccharomyces cerevisiae (Sc) and 4 strains of Torulaspora delbrueckii (Td) in sequential AF, and four strains of O. oeni (Oo) in malolactic fermentation (MLF). The objective was to describe the positive or negative relationships of these strains with the aim of finding the combination that ensures better MLF performance. In addition, a new synthetic grape must has been developed that allows the success of AF and subsequent MLF. Under these conditions, the Sc-K1 strain would be unsuitable for carrying out MLF unless there is prior inoculation with Td-Prelude, Td-Viniferm or Td-Zymaflore always with the Oo-VP41 combination. However, from all the trials performed, it appears that the combinations of sequential AF with Td-Prelude and Sc-QA23 or Sc-CLOS, followed by MLF with Oo-VP41, reflected a positive effect of T. delbrueckii compared to inoculation of Sc alone, such as a reduction in L-malic consumption time. In conclusion, the obtained results highlight the relevance of strain selection and yeast-LAB strain compatibility in wine fermentations. The study also reveals the positive effect on MLF of some T. delbrueckii strains.

Valorisation of fresh waste grape through fermentation with different exogenous probiotic inoculants

The disposal of fresh waste grape berries restraining the sustainable development of vineyards. The aims of this study were to evaluate the effects of different exogenous probiotic inoculants on the fermentation of fresh waste grape berries. In the fermentation process, the variations of pH and EC value, chemical characteristics of the fermentation products, as well as the microbial communities' composition were simultaneously observed. In addition, the feasibility of using the fermentation products as chemical fertilizer substitute in agricultural production also has been verified in this study. The results indicated that the different probiotic inoculants has shown clear impacts on the variation trends of pH and EC value in the grape waste fermentation. Lactobacillus casei and Zygosaccharomyces rouxii are ideal probiotics for the fermentation of waste grape, which enhanced the contents of free Aa and other nutrients in fermentation products. Compared with Fn treatment (without exogenous inoculants), the total free Aa contents in Fs (inoculation with Z. rouxii) and Fm (inoculation with L. casei and Z. rouxii mixture) treatments have improved by 199.1% and 325.5%, respectively. The microbial communities’ composition during the fermentation process also been greatly influenced by the different inoculants. At the genus level, Lactobacillus and Pseudomonas were the dominant bacteria, while Saccharomyces and Candida were the dominant fungi in the fermentation. Using the fermentation products as chemical fertilizer substitute has enhanced the quality of Kyoho grape. Compared with traditional chemical fertilization treatment (T1), application with fermented grape waste (T2) has significantly improved VC and soluble solid contents in grape berries by 16.89% and 20.12%, respectively. In conclusion, fermentation with suitable probiotics was an efficient approach for the disposal and recycling of fresh waste grape in vineyards.

Improvement of the production technology of tokay wines based on the revealed effect of enzyme activity on the quality of grape variety

Wines of the Tokay type are produced using a special technology. According to Hungarian technology, for the production of these wines, bunches of white and red grape varieties are twisted on the vine, withered for a certain time, then dropped for processing. At the same time, the percentage of sugar in grapes is artificially increased due to the evaporation of moisture. In pre-dried grapes, the percentage of sugar should be in the range of 40–45 %. For the production of Tokay-type wines, the fermentation of grape must is carried out naturally without the addition of alcohol and other ingredients. After formation in the must of 14‒16 vol. % alcohol, the fermentation process is suspended naturally. As a result, natural sugar and alcohol remain in the wine material. Withered grape varieties, despite their high sugar content, are economically inefficient due to low juice yield and a quantitative decrease in extractive substances. Thus, the enrichment of wine material for the production of Tokay-type wines has not been studied. As an object of research, ripe technical grape varieties Bayan Shirey, Rkatsiteli, Cabernet Sauvignon, Madrasa cultivated in the foothills of the Geygol district and in the low-lying zone of the Samukh district were used. Grape varieties were harvested from the vineyards of the winery, located in the Goygol district and from the farm "Amin", located in the village of Gara-Yeri, Samukh district. For the production of wine, both ripe and separately withered grape varieties were used, twisting on the vine for 10–12 days. However, when twisted on the vine, about 15–20 % of the bunches of grapes break and fall to the ground. Further, in ripe and withered grape varieties, the quantitative content of dry matter, total sugar, including glucose and fructose, phenolic compounds, titratable acidity, vitamin C, and in both variants the yield of unclarified juice was determined separately. The regularities of increasing the activity of enzymes of the class oxidoructase and a representative of hydrolase-pectinesterase were considered. The results make it possible to adjust the quality indicators of grape varieties depending on their zoning and use them for the production of high-quality Tokay-type wines.

THE PRODUCTION OF LOW-ALCOHOL WINES BY SEQUENTIAL SEMI-ANAEROBIC MUST FERMENTATION

Nowadays, consumers go towards products that provide food security and nutritional richness, consumption of highly alcoholic beverages not complying with these health-related requirements. This study aimed to obtain low-alcohol wines by performing sequential alcoholic fermentation of grape must (Muscat Ottonel). Thus, 11 commercial yeast strains (10 Saccharomyces cerevisiae and 1 Torulaspora delbrueckii) were preliminarily tested in anaerobic and semi-anaerobic conditions. Based on laboratory tests, grape must fermentation was sequentially initiated in semi-anaerobic conditions (loose cotton plugs; intermittent homogenization), with the T. delbrueckii strain (106 CFU/mL) and the addition of preliminarily selected S. cerevisiae strains (104 CFU/mL), to the consumption of 50% of the sugars in the must, to complete the fermentation. By applying this technology, dry wines were obtained with an alcohol content lower by up to 1.10% vol., but with a lower concentration of volatile terpenes, due to additional must oxidation. Also, semi-anaerobiosis enhanced glycerol synthesis by yeasts (< 35%), with a positive impact on the sensory characteristics of the wine.

Prediction of Ethanol Content and Total Extract Using Densimetry and Refractometry

This study investigated the interrelationships between the parameters of density, optical refraction, the volume fraction of ethanol and the total extract, using model solutions and samples of wine materials. The regularities of changes in refractometer readings in the process of alcoholic fermentation have been studied. The functional dependence of the value of the volume fraction of ethanol in the finished wine products on the density and scale of refractometer values has been established. A technique is proposed for controlling the process of alcoholic fermentation of grape must, based on the use of refractometry. Finally, we present an algorithm to calculate the composition (volume fraction of ethanol, mass concentration of the total extract) of the fermentation product from its physical properties (density, refractive index), the coefficient of determination was R2 = 0.975.

Effects of two Saccharomyces cerevisiae strains on physicochemical and oenological properties of Aranèle white wine

Aranèle is a suitable and excellent wine grape variety in Changli County, which is an important wine-producing region in China. In this study, the effects of two different yeast strains on organic acids, phenolic compounds, amino acids, and aroma compounds during Aranèle white wine fermentation were evaluated. Saccharomyces cerevisiae QA23 required longer times to ferment grape must compared to S. cerevisiae OKAY™. Tartaric acid was predominant among organic acids, accounting for over 40% of total acids quantified. Among amino acids, arginine, tyrosine and phenylalanine decreased notably, while proline increased considerably during fermentation. Moreover, the contentraion of esters (e.g., ethyl octanoate, ethyl caprate), alcohols (e.g., phenethyl alcohol, pentanol), and acids (e.g., hexanoic acid, octanoic acid) increased considerably during fermentation. Furthermore, total phenolic content in wines fermented with QA23 was higher than the OKAY™ fermented wines. Understanding the effects of Saccharomyces cerevisiae QA23 and OKAY™ on the fermentation of Aranèle grapes could be advantageous for commercial winemaking in wine-producing regions in China.

Influence of Native S. cerevisiae Strains on the Final Characteristics of “Pago” Garnacha Wines from East Spain

This work studies the variability of the Saccharomyces cerevisiae present during the spontaneous fermentation of Garnacha grapes’ musts from a “Pago” winery from the east of Spain. The parameters used to select yeast are those related to growth, fermentative behaviour, and the influence on the wine’s aroma and polyphenolic composition. Yeast identification was performed by ITS analysis and typed by Hinfl mDNA restriction profile analysis. Growth and metabolic characteristics of the isolates were determined by laboratory-scale fermentations of sterile Garnacha must, and the composition of the polyphenolic and the volatile compounds, and the sensory attributes of the small-scale produced red wines were determined. Ten S. cerevisiae strains were isolated and characterized. Overall, strain 22H quickly grew, produced wines with moderate ethanol concentrations and low volatile acidity, and obtained the highest colour and aroma scores, plus a high score for sensory attributes.

Influence of Prefermentative Cold Maceration on the Chemical and Sensory Properties of Red Wines Produced in Warm Climates

Red wines produced in warm climates generally possess a lower content of phenolic compounds and color structure than those produced in colder climates, which hinders bottle evolution. To improve these properties, cold maceration could be a useful procedure. To study the effect of this technique, Tempranillo, Merlot and Syrah grape varieties cultivated in the Jerez area (Southwest Spain) were cold macerated at 4 °C for ten days before alcoholic fermentation. Their composition and characteristics compared to the directly fermented control grapes were analyzed for phenolic content, color, volatile compounds, and sensory properties. It has been verified that phenolic content increased by around 10% during the treatment, which was maintained after the alcohol fermentation, along with an increase in color intensity and aromatic profile. This modification on the composition provided better scores for appearance, aroma intensity, and aroma quality in sensory analysis. The evolution of all studied parameters during 12 months of aging in the bottle is also studied, confirming the advantages of this technique in preserving the compositional and sensory characteristics throughout the period studied.

Conception of a biofilm bioreactor for continuous alcoholic and malolactic fermentations of grape must

Conception of a biofilm bioreactor for continuous alcoholic and malolactic fermentations of grape must

Forests influence yeast populations vectored by insects into vineyards.

In the vineyard, yeast communities impact the ripening and fermentation of grapes and are influenced by geographical location, climate, and soil characteristics. Despite the great advancement in our knowledge of the vineyard mycobiota, a key step of the process leading to the definition of the vineyard yeast community is still poorly understood: if geography, climate, and soil influence the mycobiota, potentially through selection, where do the yeast originate from, and how can they reach the vineyard? In this perspective, it is currently acknowledged that forests host several yeast species and that insects, particularly social wasps, can vector and maintain the yeasts known to populate the vineyard. Alas, the conveyance, fostered by insects, of yeasts from the forest to the vineyard has not been proven yet. In this study, we aimed to assess the existence of links between a potential natural source of yeasts (woods), the vectors (social wasps), and the composition of the vineyard mycobiota. For this purpose, the mycobiota of wasps caught in six Italian vineyards were analyzed over 2 years through culturomics approaches. The results clearly indicate that the presence of wooded areas close to vineyards is associated with particular features of the mycobiota vectored by social wasps. Wasps caught in vineyards near wooded areas bear a higher number of yeast cells and higher biodiversity than insects caught in vineyards far from woods. Furthermore, insects caught in vineyards close to woods bear distinctive yeast populations, encompassing species such as Saccharomyces cerevisiae. Overall, our work provides fundamental insights into the ecology of the vineyard mycobiota and highlights the need to maintain a vineyard-woodland mosaic landscape, thus preserving the suitable habitat for yeast species relevant to wine-making.

Yeast communities before and after spontaneous fermentation of wine grapes: a case study from Nova Scotia.

Wine fermentations are generally completed by the domestic yeast Saccharomyces cerevisiae, but many indigenous vineyard yeasts also influence wine flavour and aroma. Despite the flourishing wine industry in Nova Scotia, there has yet to be any systematic evaluation of these yeasts in Atlantic Canada. The yeast communities of pressed L'Acadie blanc grapes sampled from an organic vineyard in the Annapolis Valley in 2018 and 2019 were characterized before and after spontaneous fermentation by both Illumina and PacBio sequencing, to address and compare potential platform biases. Chemical and sensory evaluations were also conducted. Basidiomycete yeasts, including Vishniacozyma carnescens, Filobasidium globisporum, and Curvibasidium cygneicollum, dominated pre-fermentation diversity. Species of Saccharomyces made up ∼0.04% of sequences prior to fermentation, but 85%-100% after fermentation, with some replicates dominated by S. cerevisiae and some by S. uvarum. PacBio sequencing detected high proportions of Hanseniaspora uvarum, while Illumina sequencing did not. A better understanding of Nova Scotia vineyard yeast communities will allow local wine makers to make better use of non-traditional yeasts and spontaneous fermentations to produce high-quality wines unique to the region.

Sexually-Driven Combinatorial Diversity in Native Saccharomyces Wine Yeasts

Natural diversity represents an inexhaustible source of yeasts for the diversification of wines and the improvement of their properties. In this study, we analysed the genetic diversity of autochthonous Saccharomyces cerevisiae wine yeasts in the Aljarafe of Seville, one of the warmest winemaking regions of Spain. Through multiplex-PCR analysis of five microsatellite markers and RT-PCR determination of the killer genotype, we found 94 different patterns among 150 S. cerevisiae yeast strains isolated from spontaneous fermentation of grape must, thereby representing a highly diverse population. Remarkably, 92% of the isolated strains exhibited high sporulation capacity. Tetrad analysis of sporulating strains rendered a microsatellite marker’s combinatory that mimics patterns observed in the native population, suggesting that the high polymorphism of microsatellite markers found in these wild yeasts might result from sexual reproduction in their natural environment. The identification of unconventional M2/L-A-lus totivirus combinations conferring the killer phenotype also supports this suggestion. One idea behind this study is to determine to what extent the vineyards microbiota in areas with warm climates can provide useful natural yeasts to adapt fermentation processes to the needs imposed by global warming. Analysis of traits of oenological interest in regions potentially affected by global climate changes, such as growth tolerance to ethanol and to sugar stress in the analysed strains, indicated that this broad combinatorial diversity of natural S. cerevisiae yeasts provides a wide range of autochthonous strains with desirable profiles for quality winemaking in warm regions. This combinatorial diversity renders strains with diverse oenological performing abilities. Upon microvinification assays and organoleptic attests, a S. cerevisiae strain with interesting oenological properties has been identified. This result can be considered a successful outcome in industry–academia collaboration.

Fermented grape seed meal promotes broiler growth and reduces abdominal fat deposition through intestinal microorganisms.

The fermentation of grape seed meal, a non-conventional feed resource, improves its conventional nutritional composition, promotes the growth and development of livestock and fat metabolism by influencing the structure and diversity of intestinal bacteria. In this study, the nutritional components of Fermented grape seed meal (FGSM) and their effects on the growth performance, carcass quality, serum biochemistry, and intestinal bacteria of yellow feather broilers were investigated. A total of 240 male 14-day-old yellow-feathered broilers were randomly selected and divided into four groups, with three replicates of 20 chickens each. Animals were fed diets containing 0% (Group I), 2% (Group II), 4% (Group III), or 6% (Group IV) FGSM until they were 56 days old. The results showed that Acid soluble protein (ASP) and Crude protein (CP) contents increased, Acid detergent fiber (ADF) and Neutral detergent fiber (NDF) contents decreased, and free amino acid content increased in the FGSM group. The non-targeted metabolome identified 29 differential metabolites in FGSM, including organic acids, polyunsaturated fatty acids, and monosaccharides. During the entire trial period, Average daily gain (ADG) increased and Feed conversion ratio (FCR) decreased in response to dietary FGSM supplementation (p < 0.05). TP content in the serum increased and BUN content decreased in groups III and IV (p < 0.05). Simultaneously, the serum TG content in group III and the abdominal fat rate in group IV were significantly reduced (p < 0.05). The results of gut microbiota analysis showed that FGSM could significantly increase the Shannon and Simpson indices of broilers (35 days). Reducing the relative abundance of Bacteroidetes significantly altered cecal microbiota composition by increasing the relative abundance of Firmicutes (p < 0.05). By day 56, butyric acid content increased in the cecal samples from Group III (p < 0.05). In addition, Spearman’s correlation analysis revealed a strong correlation between broiler growth performance, abdominal fat percentage, SCFAs, and gut microbes. In summary, the addition of appropriate levels of FGSM to rations improved broiler growth performance and reduced fat deposition by regulating gut microbes through differential metabolites and affecting the microbiota structure and SCFA content of the gut.

Innovative “Soft” Maceration Techniques in Red Grape Fermentation

Two innovative soft maceration techniques of vinification based on red grape Cabernet Sauvignon were compared in 2020 and 2021 vintages with the most used system of maceration (pump-over and delestage) in today’s wine sector in order to verify the efficiency in polyphenol extraction and fermentation rate. Fermentation kinetics and final wine characteristics were evaluated as the main parameters for comparing the systems. The AIR MIX (AIRMIXING M.I.™) technique is based on the use of a fixed sequential small injections of compressed air (3 jets) from the bottom of the tank, aimed at creating waves (resonance waves) able to prevent the cap formation. The ADCF (NECTAR-ADCF™) technique uses the overpressure produced by carbon dioxide in the wine tank during alcoholic fermentation to keep the cap submerged and to favor its disruption by the CO2 outside release through a valve. As a reference, the control vinification consisted of the use of “delestage” and pump-over to facilitate the extraction and good management of the cap. ADCF, at the end, extracted a greater quantity of polyphenols and anthocyanins. AIR MIX speeded up the fermentation, which ended 4–7 days before the control and, initially, provoked a greater extraction of phenols and anthocyanins as ADCF. By the end, the concentration of polyphenols and anthocyanins was the highest in ADCF, followed by control and AIR MIX approximately at the same amount. The control wine had a slightly higher volatile acidity. AIR MIX consumed more than 60% less energy because the nonuse of pump-over and delestage, and also, no personnel was requested.

Bacterial Communities Related to Aroma Formation during Spontaneous Fermentation of 'Cabernet Sauvignon' Wine in Ningxia, China.

Bacteria are an important part of wine ‘microbial terroir’ and contribute to the formation of wine flavor. Based on high-throughput sequencing and non-targeted metabonomic technology, this study first explored the bacterial composition and its effect on the aroma formation of spontaneously fermented ‘Cabernet Sauvignon’ (CS) wine in the Eastern Foot of Helan Mountain (EFHM), Ningxia. The results showed that there were significant differences in bacterial communities during fermentation of CS grapes harvested from different sub-regions of EFHM, with the earlier-established vineyard obtaining more species. The level of bacterial diversity initially decreased and then increased as the fermentation proceeded. Malolactic fermentation (MLF) was spontaneously initiated during alcohol fermentation (AF). Pantoea, Lactobacillus, Rhodococcus, Fructobacillus, and Komagataeibacter were the core bacterial genera in the fermentation mixture. Lactobacillus contributed to the synthesis of methyl and isobutyl esters and the formation of red and black fruity fragrances of wine. Fructobacillus was closely related to the synthesis of aromatic alcohols and the generation of floral flavors.

The Use of Hanseniaspora occidentalis in a Sequential Must Inoculation to Reduce the Malic Acid Content of Wine

In this study, the impact of the apiculate yeast Hanseniaspora occidentalis as a co-partner with Saccharomyces cerevisiae was investigated in a sequential-type mixed-culture fermentation of Muscaris grape must. As with other fermentation trials using Hanseniaspora strains, a significant increase in ethyl acetate was observed, but most intriguing was the almost complete abolition of malic acid (from 2.0 g/L to 0.1 g/L) in the wine. Compared to the pure S. cerevisiae inoculum, there was also a marked increase in the concentrations of the other acetate esters. Modulation of some of the varietal elements, such as rose oxide, was also observed. This work shows the promising use of H. occidentalis in a mixed-culture must fermentation, especially in the acid modulation of fruit juice matrices.

The impact of indigenous Saccharomyces cerevisiae and Schizosaccharomyces japonicus on typicality of crystal grape (Niagara) wine

Schizosaccharomyces japonicus have been found as dominant yeast species coexisting with Saccharomyces cerevisiae during late stages of spontaneous fermentation of local grapes in Guizhou, China. Therefore, this study further investigated the impacts of the two indigenous yeast species on typicality of crystal grape (Niagara) wine. Five indigenous and one commercial S. cerevisiae strains were firstly selected based on their genotypes and fermentation traits in synthetic medium. All the six S. cerevisiae exhibited high tolerance to glucose, temperature, and SO2. The two killer active strains FBKL2.996 and FBKL2.9126 showed relative higher tolerance capacity of ethanol, pH and osmotic pressure than the other four S. cerevisiae strains. Further pure fermentation of six strains using crystal grape must exhibited different contents of volatile compounds, with commercial strain CECA producing the highest levels of acetate esters (phenethyl acetate), ethyl esters (ethyl caprylate, ethyl hexanoate), n-caprylic acid isobutyl ester, and terpenes (linalool) whereas being ranked the last in the sensory analysis. The co-inoculation of indigenous S. japonicus with each of the six S. cerevisiae strains increased the acetate esters (mainly isoamyl acetate) by 2–3 times in crystal grape wine. The indigenous S. cerevisiae FBKL2.9128 showed the most obvious variation of volatile compounds between pure and mixed fermentation, exhibiting the significant increase of isoamyl acetate, ethyl decanoate, ethyl caprylate, ethyl hexanoate, methyl decanoate, and dodecanal when co-inoculated with S. japonicus. Sugar addition in immature crystal grape juice increased the ethanol, glycerol, and some volatile compounds such as ethyl butyrate, but decreased the volatile compounds with floral and animal odors. The aroma sensory analysis confirmed the decrease of varietal aroma in wines with sugar addition when comparing with wines made from immature crystal grape. The results of this study provide basic information on the impact of indigenous S. cerevisaie and S. japonicus, and sugar addition on typicality of crystal grape wine, which would help to improve the wine flavor made from crystal grape in southwest China.

Lactic acid bacteria as an adjunct starter culture in the development of metabiotic functional black pearl grapes beverage

Black pearl Grapes are highly nutritious and one of the richest sources of polyphenols, but due to being delicate with very high loss at harvest and during distribution, is not consumed adequately. This study intended to develop functional lactic acid starter culture based fermented grapes beverage, in order to improve the quality and stability of this low pH fruit and to develop a fermented non-dairy beverage. Results showed that grapes blend was an excellent matrix for LAB growth with more than 9.38 log10 CFUml-1 of viability at the end of fermentation. LAB fermentation affectedly enhanced the total polyphenols and flavonoids content. Likewise, antioxidants capacities based on DPPH and FRAP activity were considerably increased correlating with each other, impacting the color and sensory properties of the grapes beverage. This way, the lactic acid fermentation can be considered as an appropriate tool for developing black pearl grapes based novel bio-intervention with enhanced antioxidants, polyphenols and flavonoids with anti-proliferative activity and antagonistic efficacy against recurring food borne pathogen in this post-antibiotic era.

Kinetics and mathematical model of killer/sensitive interaction under different physicochemical conditions of must/wine: a study from a biological point of view.

Fermentation of grape must to wine is carried out by a complex microbial mixture, which also involves spoilage yeasts of wine. The latter yeasts produce organoleptic changes that cause significant economic losses to the wine industry. SO2 is traditionally used to control this spoilage populations, but because of its harmful effects on human health, biocontrol has emerged as an alternative treatment. Although studies have been carried out to select biocontroller yeasts and examine their underlying mechanisms of action, reports on their application have not been published yet. To better understand the interaction and the successful application of biocontrol, the use of mathematical models, among other methods, is important, as they facilitate the prediction of success or failure of the antagonist. The objective of the present study was to use an existing mathematical model to obtain information about the yeast's interaction assayed and to validate its predictive use under different physicochemical conditions during the wine fermentation, and eventually predict biocontrol kinetics. The mathematical model was applied to the fermentation conditions and provided information on the kinetic parameters of the biocontrol interaction and allowed interpretations about other parameters. The model was applied in the different physicochemical conditions for the biocontrol and did not fit correctly to experimental data, and therefore an improvement was proposed which was successful and presented new hypotheses.