Search

Official stable isotope databases, based on the analysis of (D/H)The analyses were performed by isotope ratio mass spectrometry and site-specific natural isotope fractionation by nuclear magnetic resonance, in accordance with the official methods of the International Organization of Grapes and Wine. The comparison shows the tendency of some stable isotope ratios of hybrid varieties, in particular (D/H)For the first time, and from an isotopic point of view, the present study investigates the wine obtained from hybrid varieties, showing that further attention should be paid to their interpretation, on the basis of the database established according to the European Regulation 2018/273. © 2022 Society of Chemical Industry.

Bacteria can play different roles affecting flavors and food characteristics. Few studies have described the bacterial microbiota of butter. In the present paper, next-generation sequencing was used to determine bacterial diversity, together with aromatic characteristics, in raw cow milk butter processed by traditional fermentation, in fourteen small farms called “Malga”, located in the Trentino province (Alpine region, North-East of Italy). The physicochemical and aromatic characterization of traditional mountain butter (TMB) showed a low moisture level depending on the Malga producing the butter. Counts of lactic acid bacteria, Staphylococci, and coliforms, as well as diacetyl/acetoin concentrations exhibited changes according to the geographical origin of Malga and the residual humidity of butter. MiSeq Illumina data analysis revealed that the relative abundance of Lactococcus was higher in TMB samples with the highest values of acetoin (acetoin higher than 10 mg/kg). The traditional mountain butter bacterial community was characterized by a “core dominance” of psychrotrophic genera, mainly Acinetobacter and Pseudomonas, but according to ANCOM analysis, a complex bacterial population emerged and specific bacterial genera were able to characterize the TMB bacteria community, with their high abundance, based on the Malga producing the butter.

Atypical ageing (ATA) is an aroma defect that occurs in white wines and entails a loss of varietal aromas as well as scents of wet mop, shoe polish and dish rag. 2-Aminoacetophenone (2AAP) - a degradation product of indole-3-acetic acid (IAA) - has been described as the main odour-active compound and chemical marker responsible for this off-flavour. A stress reaction in the vineyard triggered by climatic, pedological and viticultural factors can ultimately cause ATA development in wines and remarkably affect wine quality. The aim of this research was to investigate the influence of three grapevine management systems on the occurrence of ATA. The experiments were carried out on Pinot Blanc grape samples from vines cultivated using one conventional and two organic approaches. The management systems mainly differed for the fertilisation regime and the weed control.The amino acid profiles as well as 2AAP and its precursors were quantified in musts and wines using ultra-high-performance liquid chromatography coupled to a high-resolution mass spectrometer. The results showed the existence of a strong vintage effect, while no influence of the use of different agronomic systems was observed.The study revealed that an efficient implementation of different grapevine production systems did not affect ATA development in Pinot Blanc wines. This finding is of great relevance for winegrowers and winemakers as it demonstrates that a well-planned organic management system correctly adjusted to the climatic conditions does not pose a threat towards the development of ATA-related compounds in wine. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John WileySons Ltd on behalf of Society of Chemical Industry.

The high demand for wine in Europe has increased the impact of viticulture on the environment. In line with European objectives, more sustainable agronomic practices have spread as an alternative to traditional management. This study aimed to compare, in a vineyard of Pinot blanc and Rhine Riesling in northeast Italy, the integrated agronomic practices (INT) with two types of organic management (ORG1—cattle manure and ORG2—green manure), in terms of production, grape quality, pest susceptibility, and soil nutrient availability. The results, after the fifth, sixth, and seventh year of testing, showed that organic management obtained a yield and vegetative features comparable to INT. Grape quality also did not show considerable overall differences between the theses in the must properties, despite the higher total sugar content and lower yeast available in ORG1. In the three-year period, the management of downy mildew, powdery mildew, and rot, as well as the soil fertilization, with the products available in organic farming proved to be comparable to the INT method. The application of cattle manure contributed by enriching the soil in K and P, while a balanced green manure mix has proven to be the best agronomic practice in terms of the release of mineral N during the phenological stages of greatest need of the vine. Organic management appears as an agronomic strategy able quantitatively and qualitatively support the vineyard system.

Gum arabic (GA) is the oldest and best known of all natural gums. Thanks to the particular characteristics resulting from its complex mixture of polysaccharides and glycoproteins, its field of application is extensive. In the oenological sector, it is used to prevent colour depigmentation and protein precipitation and although there is no declared limit, the International Code of Oenological Practices suggests not exceeding a dosage of 300 mg L−1. In this study, the botanical origin (Acacia senegal vs A. seyal) and commercial description (Kordofan region vs other Sub-Saharan areas, based on the traditional geographic provenance) were defined studying 44 GA samples with a non-targeted screening approach using high resolution mass spectrometry. From an initial group of 88 identified masses, 15 were selected to create a bi-factor PLS-DA statistical model able to correctly reclassify samples with 94.4% accuracy. Moreover, the study addressed the question of identifying gum addition in wines, analysing 98 untreated wines and comparing them with 40 wines to which gum arabic had been added (200 mg L−1). Considering the database of 88 masses, 4 of them were established to be markers of gum arabic addition (m/z 152.1067, 166.1225, 585.1428 and 643.1403). Principal component analysis performed with the signal (area) of the 4 masses highlighted three groupings differentiating untreated wines, wines treated with A. senegal gum and wines treated with A. seyal gum. m/z 152.1067 was tentatively identified as N-methyltyramine, while m/z 166.1225 as N,O-dimethyltyramine.

The development in young white wines of 2-aminoacetophenone, commonly known as atypical aging defect (UTA), leads to unpleasant notes such as mothball, wet mop, sweaty, acacia blossom, or soap. Tryptophan and indole-3-acetic acid, the most abundant auxin in plants, are considered to be the primary precursors of this compound. Indole-3-acetonitrile; indole-3-lactic acid; skatole; tryptophol and the inactivated form of the auxin N-(3-indolylacetyl)-L-alanine; N-(3-indolylacetyl)-DL-aspartic acid; and methyl-indole-3-acetate can act as potential precursors of 2-aminoacetophenone and contribute directly to UTA scents in wines. This paper investigates the distribution of 2-aminoacetophenone precursors or intermediate metabolites (n = 9) in grape berry tissues (pulp, skin, and seeds) in 12 samples of four different varieties: Cabernet Cantor, Chardonnay, Merlot, and Solaris. Chardonnay (three lots) was analyzed in more depth by evaluating precursor extraction during industrial pressing at different stages. For quantification, this study developed and validated a method using high-performance liquid chromatography coupled with high-resolution mass spectrometry. It used a pre-concentration and purification solid-phase extraction-online system and had a detection limit between 0.25 and 2 µg/L, depending on the compound. Despite significant varietal differences, indole-3-acetic acid was more abundant in seeds and skin fractions. Only ~30% of the total berry amount was extracted with free-run pressing, but ~80% was extracted at 0.6 bar. This suggests a fundamental role of pressing in managing the development of UTA during winemaking.

In this work, the anthocyanins’ profile of two hybrid grape varieties—Cabernet Carbon and Prior—grown in two experimental plots in Trentino (Northern Italy) was investigated during 2016 and 2017 harvests. The focus was on the mono- and di-glycoside anthocyanins extraction during the fermentative maceration. It was optimized an HPLC-DAD method, which allows the separation and quantification of mono- and di-glucoside anthocyanin forms (non-esterified, acetylated, and p-coumaroylated) in a single chromatographic run. Furthermore, an HPLC-DAD/HQOMS approach was used to confirm the compound identification. The skin contact fermentation was conducted for 7 days at 24 °C, punching down manually the cap twice a day. Must samples were collected every 24 h. As expected, every anthocyanin showed an initial net extraction phase described by a first-order kinetic, followed by a decrease until the end of the maceration. The analysis of the accumulation rate showed a faster increase of the di-glucoside anthocyanins concentration compared to the corresponding mono-glucoside, due to their richness in the initial grapes. Moreover, the di-glucosides concentration at the end of the alcoholic fermentation underwent a three times minor percentage decrease with respect to the maximum reached. This paper intend to improve the knowledge of the kinetics of each anthocyanin form during the maceration step, providing information about the behavior of di-glucoside compounds, never investigated before in terms of accumulation and percentage decrease.

Bacteria have a fundamental role in determining the fitness of grapevine, the composition of grapes and the features of wines but at present, little information is available. In this work, the bacteria colonizing the different portions of grapevine (bark, leaves and grapes) were explored in the vineyards of the Alpine region of Trentino, considering the impact of different environmental and agronomical variables. The vineyards included in the work were selected based on their different geographical positions (altitude) and grapevine training systems in order to explore the whole variability of the grapevine ecosystem. Moreover, the surface amount of copper was measured on grapes and leaves during the vegetative growth. Bacterial analysis, performed using plate counts and Illumina MiSeq, revealed an increase in the concentration of grape bacteria proportional to the progress of the ripening stage. Conversely, the peak of bacterial concentration onto leaf and bark samples occurred in August, probably due to the more favourable environmental conditions. In bark samples, the bacterial microbiota reached the 7 log CFU/cm2, while 6 log UFC/g were measured in grape samples. A remarkable biodiversity was observed, with 13 phyla, 35 classes, 55 orders, 78 families and 95 genera of bacteria present. The presence of some taxa (Alphaproteobacteria, Desulfovibrionaceae, Clostriadiales, Oscillospira, Lachnospiraceae and Bacteroidales) was ubiquitous in all vineyards, but differences in terms of relative abundance were observed according to the vegetative stage, altitude of the vineyard and training system. Bacteria having oenological implication (Lactobacillus, Pediococcus and Oenococcus) were detected in grape samples collected in August, in low abundance. The data revealed a complex bacterial ecosystem inside the vineyard that, while maintaining common traits, evolves according to environmental and agronomical inputs. This study contributes to define the role of bacteria in the complex balance established in each vineyard between human actions and agricultural environment, known as terroir.

Polyphenols, especially anthocyanins, play an important role on red wine sensory qualities and their evolution during storage. High Power Ultrasound (HPU) has been recognized as one of the most promising technologies which can be applied in winemaking processes for several purposes, and it is recently officially approved for crushed grapes treatments. The effect of ultrasound amplitude (41 and 81%) and treatment time (1, 3, and 5 min) has been studied on anthocyanins, flavan-3-ols, tannins, polymerized pigments, HCl index, and the color intensity of two finished red young wines. Anthocyanins and phenols compounds were not degraded with an increase in amplitude and sonication time, and the chromatic properties of the selected wines were preserved. Amplitude and ultrasound time were also evaluated considering their effect on evolution of anthocyanin content and phenolic stability indices during the first thirty days of storage. The higher level of amplitude (81%) induced a higher percentage decrease in tannins, 15% and 40% after 15 and 30 days of storage, respectively, compared to untreated wine which did not show a significant change during storage. HPU shows a possible chemical effect on the evolution of some analytical indices during bottling maturation, but their effectiveness could be strictly linked with the initial phenolic profile and ratios between polyphenol classes.

The biodiversity of Saccharomyces cerevisiae was studied in the Montalcino area (Italy). Two wineries were involved in the study, which compared the genotypic and oenological characteristics of the S. cerevisiae strains isolated in spontaneous fermentations. After isolation yeasts were identified by 26S rRNA gene sequence analysis, and S. cerevisiae strains were characterized through interdelta sequence analysis (ISA). Oenological tests were performed in synthetic grape must by varying the magnitude of the main wine-imiting factors. The evolution of alcoholic fermentation was monitored by measuring sugar consumption and flow cytometry. The results revealed the prevalence of S. cerevisiae from the third day of fermentation and the presence of a wide range of S. cerevisiae strains having ISA profiles characteristic of each winery. From an oenological point of view, the features of such strains, in terms of resistance to wine-limiting factors, seemed to be linked to the main oenological variables applied in the production process of each winery. Extreme fermentation temperatures and copper residues are the variables that mostly depress the yeast population, in terms of fermentation rate and cell viability. Flow cytometry revealed the different impact of limiting factors on the viability of yeast by the quantification of the ratio between live/dead yeast cells of each strain, suggesting different mechanisms of inhibition, for instance stuck of cell growth or cell killing, in response to the different stress factors.

Atypical aging of white wines (ATA) is an off-flavour characterised by rapid loss of fruity aromas and the development of unpleasant odours. This study aims to evaluate the effectiveness of different oenological adjuvants (4-ethylcatechol, 4-methylcatechol, gentisic acid, hydroxytyrosol, ascorbic acid, glutathione, ellagic acid, gallic acid, galla tannin, ellagic tannin, quebracho, grape tannins) added to musts before fermentation for preventing the possible development of ATA. High resolution mass spectrometry made it possible to quantify and qualify free and conjugated IAA in wine at the end of the fermentation and subsequently 2-aminoacetophenone (AAP) was quantified after the force ageing period (6 days at 40 °C). Ascorbic acid was confirmed as the most appropriate antioxidant adjuvant which can be used for ATA defect prevention. With an almost comparable effect, gallotannin addition prevented AAP production to exceed 1 μg/L. A predicted model (ANCOVA) indicated that over 80% of the variability of potential AAP formation in wines was explained by the amount of precursors, grape variety and antioxidant treatment. Moreover, a suspect screening approach made it possible to study the kinetic formation and the consumption of the reaction metabolites formed during the oxidative degradation of IAA leading to AAP.

The effect of ultrasound (20 kHz, 153 &mu, m) on the prefermentation extraction mechanisms in Sauvignon Blanc grapes was studied, focusing on 3-mercaptohexan-1-ol (3MH) and 4-mercapto-4-methyl-pentan-2-one (4MMP) precursors linked to glutathione (GSH) and cysteine (Cys). The treatment determined a positive extraction trend between the duration (untreated, 3 and 5 min) and the conductivity or the concentration of catechins and total phenols, significantly differentiated after 5 min. Nevertheless, the concentration of the thiol precursors in grape juice not only remained undifferentiated, but that of 3-S-glutathionyl mercaptohexan-1-ol showed a negative trend with the treatment time applied (168 &plusmn, 43, 156 &plusmn, 36, and 149 &plusmn, 32 &mu, g/L, respectively, for control, 3 and 5 min). The divergence on the effect between families of compounds suggests an interaction between the sonication treatment and thiol precursor molecules. In order to evaluate the possible degradation properly, ultrasound was applied in a model solution spiked with 3MH and 4MMP precursors, reproducing the conditions of grapes. Except for Cys-3MH, the mean concentration (n = 5) for the rest of the precursors was significantly lower in treated samples, predominantly in those linked to glutathione (~&minus, 22% and ~18% for GSH-3MH and GSH-4MMP) rather than to cysteine (~&minus, 6%~&minus, 8% for Cys-3MH and Cys-4MMP). The degradation of precursors was associated with a significant increase of 3MH and 4MMP. The formation of volatile thiols following sonication is interesting from a technological point of view, as they are key aroma compounds of wine and potentially exploitable in the wine industry through specific vinification protocols.

Purpose The role of fermentation temperature was studied for its impact on the evolution of malolactic fermentation performed by simultaneous inoculum of yeast and bacteria in grape must. Results were discussed considering the different fermentative kinetics and the composition of obtained wines. Methods Two strains of bacteria belonging to the O. oeni and L. plantarum species were inoculated 24 h after the beginning of the alcoholic fermentation in 2 grape musts having different acidic and sugar profiles. Fermentations were conducted at 3 different temperature profiles (16/22 °C in 3 days, 18/24 °C in 3 days, 22/32 °C in 5 days). Evolution of microbiota was followed by flow cytometry and plate count. Chemical analysis of grape musts and wines were performed by instrumental approaches (FT-IR, enzymatic quantification of malic acid, GC-MS). Results L. plantarum resulted more efficient in malic acid consumption in the entire set of tests. These results are unexpected because, generally, Lactobacillus has been reported to be more sensitive to an oenological environment than O. oeni. In our experiments, O. oeni resulted inhibited by the highest fermentation temperature profile, causing incomplete malic acid degradation. Similarly, S. cerevisiae showed a higher sensitivity to environmental limiting factors in respect to what is generally known. Differences in the chemical composition of wines were observed in relation to the bacteria strain and the temperature profile. However, the statistical treatment of data identified temperature as the main variable able to influence the features of wines. Conclusions Simultaneous inoculum of yeast and bacteria in grape must is an alternative approach in the management of malolactic fermentation which showed some interesting features. However, it is necessary to consider that the dynamics of the microbial population are different to that observed in traditional winemaking and the environmental variables act against the microorganisms in a peculiar, and in certain cases unexpected, way.

Background Over recent years, a new wave of disease-tolerant to mildew varieties has flooded the viticulture sector, for reasons of human safety and economic expediency. These hybrid grape cultivars are selected mainly on the basis of their intrinsic capability to counter the attack of the main fungal diseases that affect grape production, such as downy mildew and powdery mildew. However, their organoleptic and oenological characteristics have not yet been studied in depth for purposes of both juice and wine production, due to the high number of newly proposed germplasms and the lack of information about their adaptability to different environments. This work examines the thiol aroma precursors concentration in 64 red and white disease-tolerant hybrid varieties in the vine germplasm collections of Consiglio per la ricerca in agricoltura e l'analisi dell'economia agraria-Viticulture and Enology Research Center and Fondazione Edmund Mach, both from the north-east of Italy. Results All cultivars showed the presence of 3-mercaptohexan-1-ol (3MH) precursors, ranging from 4.4 to 1141 μg kg-1 for 3-S-glutathionyl hexan-1-ol (GSH-3MH), and from 0.3 to 136 μg kg-1 for 3-S-cysteinyl 3-hexan-1-ol. The concentration of GSH-3MH exceeded 600 μg kg-1 in eight varieties, with values comparable to those of the richest Vitis vinifera reported so far. On average, red grapes showed higher concentrations of 3MH precursors than white ones did. Only two hybrids had 4-mercapto-4-methylpentan-2-one (4MMP) precursors over the limit of quantification, albeit with a much higher concentration than those normally reported in Sauvignon Blanc. Conclusion This is the first detailed survey of 3MH and 4MMP precursors carried out taking into account a considerable number of hybrid grape varieties. The results show that some of these varieties could be interesting for the production of tropical juices or tropical-aromatic wines and soft drinks, through the enzymatic liberation of thiol aromas, as well as for the production of aromatizing tannins to be used in the food industry. © 2020 Society of Chemical Industry.

Considering the carcinogenic risk to human health, it is necessary to carry out research into arsenic (As) content in agro-food products and the impact of food processing on the final content. Yeast fermentation may represent a strategy for detoxifying some widespread beverages such as wine, beer and rice wine. A preliminary study of some commercial yeast species showed different viability responses to the presence of As. Yeasts had a noteworthy detoxification capability during fermentation, reducing the initial As content by about 75 % on average (minimum–maximum: 45–92 %), making it possible to produce wines with a considerably reduced content as compared to the corresponding grape juices from naturally As-rich soils. Nevertheless, significant differences between strains were observed in relation to resistance to arsenic toxicity and As removal capability. The choice of yeast strain can determine a difference of 40 % on the As content remaining in the wine after fermentation. Arsenic content of up to 1000 µg/L did not significantly worsen the fermentation of some wine yeasts, suggesting that the use of specific yeasts may represent an effective tool for reducing As in fermented beverages.

Sulfur chemistry remains one of the most intriguing and elusive fields in wine science. In particular, the possibility for symmetric and asymmetric glutathionylated and cysteinylated polysulfides to act as latent reservoirs for H2S warrants new research on the factors influencing the formation and accumulation of these molecules. The present research studies the impact of pre-fermentative additions of commonly employed antioxidants: glutathione, ascorbic acid, and ellagic tannin. Musts from four different white grape varieties (Riesling, Pinot gris, Pinot blanc, and Johanniter) were analysed using our comprehensive HPLC-HRMS method. Seven symmetric and asymmetric glutathionylated (G) and cysteinylated (C) polysulfides (GS2C, GS3C, GS4C, GS3G, GS4G, CS3C, and CS4C) were detected in the final 48 wine samples. Finally, this work describes for the first time the impact of an accelerated ageing of wine on the polysulfides present. All variables (Must, Treatment, and Time) were shown to impart statistically significant effects (p = 0.0001) in the PERMANOVA model. The PCAs based on polysulfides present in young and aged wine explained more than 80% of the total variance for each grape variety and showed that Asc or GSH additions have tend to produce lower levels of polysulfides in the resultant wines.

The formation of ethylphosphonate (fosetyl) was investigated in wine matrices. In experimental conditions, alcoholic fermentation of grape juices spiked with phosphonic acid resulted in wines with detectable amounts of fosetyl. The ageing period adopted for these wines further increased the fosetyl content in the absence of yeast lees, thus indicating a chemical origin. A model wine assay was performed in order to study the main thermodynamic variables affecting the Fisher reaction. The results obtained allowed us to report evidence of ethylphosphonate formation in winemaking conditions, for the first time to the best of our knowledge.

This research aimed to more clearly describe the interactions of Drosophila suzukii (Matsumura; Diptera: Drosophilidae) with microorganisms that may contribute to spoilage or quality loss of wine grapes during harvest. Experiments were conducted in controlled laboratory experiments and under field conditions to determine these effects. Laboratory trials determined the role of insect contact and oviposition to vector spoilage bacteria onto wine grapes. In the field, the roles of key organoleptic parameters in grape fruit ripening were assessed to determine their relative contribution to oviposition potential as fruit ripened. Finally, field trials determined the relationships of egg and larval infestation to sour rot levels. Non-ovipositional trials indicated elevated levels of microbiota when D. suzukii was present. D. suzukii oviposition exponentially increased the concentration of acetic acid bacteria. Both incised and sound berries showed a significant increase in concentrations of acetic acid bacteria exposed to D. suzukii. Volatile acidity was higher in treatments infested with D. suzukii. Fruit with only eggs did not develop a significant increase of volatile acidity. Larva-infested grape berries in 9.5% of samples developed higher volatile acidity after 14 d. Sound grape berries were less susceptible to the development of microbiota associated with sour rot and spoilage. D. suzukii oviposition and larval development increase risk of spoilage bacteria vectored by D. suzukii adults. Acetic acid bacteria induced fermentation and produced several volatile compounds contributing to spoilage. Spoilage bacteria may create a positive feedback loop that attracts both D. suzukii and other drosophilids, which may contribute to additional spoilage.

Thiol compounds responsible for tropical fruit associated aroma have been extensively studied over the last 20 years. The occurrence of their non-aromatic precursors in grapes and musts is reported largely mainly for the cultivar Sauvignon Blanc. The presence of these thiols as precursors or free molecules in grape, juice, and wine has been reported in several different varieties, suggesting that they are more or less ubiquitous both for Vitis spp. and interspecific hybrids. The biosynthetic pathways resulting in these compounds are yet to be completely elucidated, but, in the meantime, industry needs to improve technological knowledge to better manage winemaking steps to enhance the variety-dependent aroma of wine. In this work, we studied the implications of the use of grape skin tannins—rich and poor in thiol precursors—on the final content of 3-sulfanylhexan-1-ol (3MH) and its acetate (3MHA) in wine and the effect in terms of sensory appreciability. The evaluation of 36 vinifications carried out in a semi-industrial scale permitted us to prove that only a tannin originally rich in precursors (High), when added to juice at the beginning of fermentation, enhanced both the concentration of precursors in the juice and the final concentration of aromatic thiols in the resultant wine. The 3MH and 3MHA developed as a consequence of the juice supplementation with tannin High and increased pleasantness and typicality of Gewurztraminer wines. A later supplementation with tannin High at the end of the alcoholic fermentation was sensorially not effective.

In the seventies, the region known as Baixada Santista was a large repository of environmental contamination mainly resulting from industrial waste. In effect, the contaminated residues came from different toxic substances including chemical, biochemical and others. Industrial waste was dumped or even stored in inadequate fragile ecological sites without any previous treatment and it resulted in significant amounts of air, soil and water pollution. A male specimen of U. cordatus presenting a malformation of the pollex (immovable finger) of its major claw (left) was captured in São Vicente city, raising concern to the local press and community. The immovable finger of the propodus segment in the claw of this specimen was modified into a structure in the form of a talon. This structure resembling an avian claw was comprised of five fixed ends united at the base. This might be a result from an injury of the original corpus structure while in a confrontation with another specimen. The newly found sample showed a high incidence of micronucleated cells in the haemolymph, approximately three times higher than normally reported. Perhaps this suggests the effect of an environmental influence in the morphology of the organism, most likely linked to the several sources of pollution in the region (public dump of Alemoa/Sambaiatuba, and the industrial conglomerate of Cubatão). We propose that similar measurements could be used in the estuarine area to assess and evaluate ecological risks and adverse biological effects.

Malolactic fermentation (MLF) is a key feature in the production of high-quality wines. Its evolution is not always guaranteed, especially in white wine, due to certain limiting factors (low pH, sulphur dioxide, low temperature) acting against malolactic bacteria. The inoculation of grape must with bacteria is an alternative approach to the management of oenological fermentation, favouring the survival of bacteria due to the absence of ethanol or sulphur dioxide – toxic compounds made by yeasts in the first stages of winemaking. We compared the activity of two strains of Oenococcus oeni during MLF in wines made from an emerging white grape variety, native to north-eastern Italy, namely Incrocio Manzoni. Different winemaking protocols were assayed, comparing sequential or simultaneous inoculation of microbial starters. The monitoring of bacterial viability through fermentations and a comprehensive characterisation of the volatile profile of the wines were achieved by advanced analytical approaches, flow cytometry and GC-MS respectively. According to the preliminary hypothesis, the chemical composition of the grape must was characterised by high acidity, which represented a serious barrier to bacterial development. Simultaneous inoculation of the two O. oeni strains ensured a regular evolution of MLF. Some differences were highlighted, both in terms of fermentation kinetics and the aromatic profile of the wines obtained, in relation to the strain of lactic bacteria. The work provides an exhaustive overview of the opportunities and risks related to different wine fermentation approaches in order to enhance the quality of white wines made from “new” or “local” wine grapes.

The simultaneous inoculum of yeasts and bacteria is a feasible solution for improving fermentation in wines with a harsh chemical composition, capable of inhibiting microbial activity. Considering the risk of wine spoilage due to lactic bacteria, co-inoculum is suggested in white wines with a low pH. However, climate change has also caused problems in achieving malolactic fermentation in red wines, due to the high concentration of ethanol and the low nutrient content. In this work, 5 pairs of commercial oenological starters were tested in simultaneous fermentation, using 4 red musts with a low nitrogen content, and compared with a traditional winemaking process. The simultaneous inoculum caused a slowdown in the activity of yeasts, although no problems in the accomplishment of alcoholic fermentations were observed. More reliable malolactic fermentation was performed in the co-inoculum trials, while, in traditional winemaking, some failures in the degradation of malic acid were observed. Microbiological analyses agreed with these observations. No differences were found in yeast density during alcoholic fermentation, demonstrating the absence of negative interaction between the yeast and the bacteria. However, simultaneous fermentation is not without risks; the highest increases of acetic acid were noted in the co-inoculum trials. The addition of yeast and bacteria to must with a serious lack of nutrients would appear to be a promising alternative to traditional fermentation; however, careful control of the chemical composition of must is mandatory to obtain reliable microbiological activity in the first stages of winemaking.