Yeast Assimilable Nitrogen Research Articles

Changes in total soluble solids concentration, fruit acidity, and yeast assimilable nitrogen in response to altered leaf area to fruit weight ratio in Pinot noir

The increasing consumer demand for lower alcohol wine and the need to mitigate against a warming climate presents new challenges for winegrowers and the desire to produce grapes with lower total soluble solids (sugar) or earlier harvesting, while preserving other wine compounds and attributes, particularly for varieties intended for red wine production. We investigated how reducing vine leaf area through shoot trimming and leaf removal, applied at different severities and timings to modify the leaf area to fruit weight (LA) ratio, affects fruit composition for producing lower alcohol quality Pinot noir wine. Shoot trimming treatments (half canopy, H in 2015/16 and 2016/17, and quarter canopy, Q in 2016/17 by alternately removing leaves after trimming shoots to half) were applied shortly before veraison (V-, E-L 34), during veraison (V, E-L 35) and post-veraison (V+, E-L 36) in three different vineyard locations (Marlborough, Canterbury and Central Otago, New Zealand). Untrimmed vines served as the control. Lateral shoots were removed during treatment application, and regrowth was removed to maintain a consistent leaf area. Results showed that reducing the LA:FW ratio delayed the accumulation and concentration of total soluble solids (reduction of 1.0 to 2.7 °Brix) at harvest in all trimmed vines over both seasons. Berry weight, malic acid concentration, titratable acidity, and pH at harvest were unaffected by trimming. At target TSS levels of 18 °Brix (10 % ethanol, v/v) in the Marlborough vineyard and 20 °Brix (11 % v/v) in the Central Otago vineyard, V+ vines showed malic acid and titratable acidity levels comparable to the control. At the Canterbury vineyard, these parameters remained similar across all treatments at 16 °Brix (8.9 % v/v). Yeast-assimilable nitrogen concentration increased (188 to 411 mg/L) in early trimmed vines. At Central Otago, roots showed lower carbohydrate reserves across all trimming treatments, likely due to the high yield at the site, while at Canterbury, trimming did not result in significant differences in carbohydrate reserves, likely due to the low yield at the site. At the Marlborough vineyard, vines trimmed early and more severely had less starch in their roots, while HV+ vines maintained similar levels of starch to controls. In conclusion, halving the canopy post-veraison (HV+, LA 0.70 m²/kg as observed in Marlborough) could be considered a viable viticultural option to lower sugar accumulation, thereby reducing potential alcohol content, without affecting titratable acidity and pH. This practice offers significant potential for adapting to a warming climate and producing lower alcohol Pinot noir wines in a sustainable manner.

How to combine soil and plant indicators to manage nitrogen fertilisation in vineyards?

ContextAlthough grapevine nitrogen (N) needs are moderate, N fertilisation in vineyards requires carefully management because berry development, aromatic composition and hence winemaking are largely influenced by N nutrition. Our objective was to develop a method for reasoned N fertilisation between and during the seasons. MethodsSpecific sensitivities of soil and plant indicators to N supply and availability were estimated and indicator robustness was quantified using contrasted environmental conditions, crop management and N fertilisation in an experimental network comprising five vineyards in southern France over four successive years. The effects of four N fertilisation treatments combining contrasted amounts, forms and timing on the indicators were tested using linear models. Multiple factorial multiple analysis was used to study the effect of environmental and management factors on indicator sensitivity to mineral N fertilisation at budburst. ResultsYield, soil mineral nitrogen at budburst, chlorophyll concentration (SPAD) at veraison, leaf nitrogen content and yeast assimilable nitrogen (YAN) at harvest, were all sensitive to N fertilisation after four years. Different effects of the N treatments were observed from year three for SPAD and from year one for YAN. Additionally, SPAD and YAN indicators distinguished contrasted strategies based on different timings of N supply or the form of N fertiliser. Lastly, the response of the SPAD and YAN indicators was only slightly influenced by pedoclimatic conditions or cultural practices, at least for the variables tested here. ConclusionTwo N indicators measured from veraison (SPAD) to harvest (YAN), can provide valuable information for tactical and long-term fertilisation decisions. Notably, early SPAD information may improve technical vineyard management of interactions between fertilisation and other practices (e.g. weed control or tillage) that interfere with plant N nutrition and enable later correction of YAN values. Combining these indicators with non-destructive imaging techniques should improve N and mineral monitoring in general.

Using Legume-Enriched Cover Crops to Improve Grape Yield and Quality in Hillside Vineyards

Natural covering (NATC) has spread on hillside vineyards of central Italy as a replacement for tillage to reduce soil erosion, although it increased nitrogen and water needs. Therefore, in the current context of global warming, using cover crops (CCs) that require less water and provide nitrogen becomes crucial. The effects of two low-competition legume-enriched CCs in a rainfed hillside vineyard—a perennial legume–grass mixture (PLGM) and an annual legume cover crop of Trifolium alexandrinum (ALTA)—were compared with NATC over three years. PLGM and ALTA provided good levels of soil coverage, slightly lower than NATC, which had a negligible presence of legumes. PLGM and ALTA, due to low competition, enhanced vine vigor, resulting in thicker and wider canopies (as indicated by total leaf area and leaf layer number), higher pruning weight, and increased yield. PLGM and ALTA led to good qualitative levels, with higher grapes acidities, lower pH and total soluble solids content and, additionally, significantly higher yeast assimilable nitrogen content. In conclusion, implementing low-competition legume species in CCs is an effective tool to avoid soil erosion in a climate change scenario, leading to increased productivity, higher acidity, and improved nitrogen content in the grapes.

Production Physiology and Biochemical properties of Crude Thermophile Protease by Mild - Halophilic Bacillus thuringiensis aizawai HD 865

Objective: The current study aims to enrich the research library of Bacillus thuringensis, the most famous bacteria as a biopesticide, with a product that may enhance its ability as a biopesticide as well as its many other applications, namely the heat-tolerant alkaline protease. Methods: The strain Bacillus thuringiensis aizawai HD 865, obtained from HD Culture Collection was grown on a liquid growth medium of nutrient broth and yeast extract, and colonies were counted on agar plates. The zygote is then transferred to a skim milk environment to estimate the enzymatic activity under the different growth conditions of the growth environment (sodium chloride concentration, pH, aeration, fermentation duration), then testing the optimal conditions for enzymatic activity in the enzymatic reaction mixture (sodium chloride concentration, salinity resistance, optimum temperature, thermal stability, optimum pH and stability). Then analyze the data statistically. Results: Optimum alkaline protease medium production conditions were, 2 % NaCl, so Bacillus thuringiensis aizawai HD865 a mild - halophilic microorganism, aeration level 80%, pH 7 and 8 days of fermentation period. On the other hand, crude alkaline protease properties were found that, the optimum temperature for its activity was relatively high (70ºC), while heat-stabilities after 5 min of heating crude enzyme in boiling water bath then incubated for 15min on 30, 40, 50, 60, 70ºC, were 184.23, 178.07, 164.29, 165.51 and 121.46 Units, respectively; whereas the optimum pH was at pH 7.6 (151.76 Units) with tris buffer then at pH 9.6 with glycine - NaOH buffer; While pH stability was at pH 7.6 with tris buffer then at pH 8.4 with glycine - NaOH buffer. Thus, activities have decreased at different concentrations (0, 1, 2, 3, 4, 5 %) of sodium chloride in reaction mixture with enzyme activities (151.25, 137.35, 135.12, 135, 135.89, 114.38 Units) respectively, also decreased when rinse crude enzyme for 5 min in NaCl (0, 1, 2, 3, 4, 5 %), with (151.04, 175.57, 168.69, 154.61, 155.39 and 143.39 Units) respectively. Conclusion: Bacillus thuringiensis aizawai HD 865 strain is considered a low - salt tolerant strain, while the alkaline protease extracted from it is heat - resistant.

Exploring grapevine canopy management: effects of removing main leaves or lateral shoots before flowering

Over the course of a six-year trial, we investigated the physiological response of the Swiss white cultivar Vitis vinifera Petite Arvine, rich in varietal thiols, to the following canopy removal treatments from the cluster area, i.e. from the shoot base to the sixth leaf of each shoot: A) lateral shoots only, B) lateral shoots + 50 % main leaves, C) lateral shoots + 100 % main leaves or D) main leaves only. All leaf removal (LR) treatments were performed at the pre-flowering stage. Intensive pre-flowering removal of both lateral shoots + 100 % main leaves from the cluster area (C) strongly reduced yield potential (‒47 % on average) and tended to reduce the concentration of 3-mercaptohexanol precursors (Cys-3MH) in the must (‒21 %; p-value < 0.10). The effect of LR on berry set and must composition was modulated by removing fewer main leaves (‒24 % in yield potential and ‒6 % in Cys-3MH concentration). Climate conditions primarily influenced yield and grape composition. Main leaves and lateral shoots played different physiological roles: removal of main leaves only (D) resulted in a larger leaf area (+15 %) due to the development of lateral shoots in the cluster area and a lower yield potential (‒12 %) due to fewer berries per cluster when compared one-to-one with removal of lateral shoots only (A). In the must at harvest, treatment D had higher concentrations of malic acid (+12 %), yeast-assimilable nitrogen (+10 %) and glutathione (+8 %), but there were no significant trends for TSS, pH, Cys-3MH or Folin index. The overall effects of pre-flowering LR on wine composition were negligible in the context of this trial. The study highlighted the different physiological roles of the main leaves and lateral shoots, suggesting that pre-flowering leaf removal should be used cautiously, taking into account the plant’s resilience to environmental conditions. This research is part of a broader project on grapevine canopy management in temperate climates in Switzerland.

Effect of different nitrogen source and Saccharomyces cerevisiae strain on volatile sulfur compounds and their sensory effects in chardonnay wine

Three commercial Saccharomyces cerevisiae strains with low, medium, and high H2S-producing capacity were chosen to investigate the effect of yeast assimilable nitrogen (YAN) levels and composition on volatile compounds in a chemically defined medium, specifically high, medium, and low initial YAN levels with varying proportions of DAP or sulfur-containing amino acids (cysteine and methionine). The results revealed that the initial YAN containing a larger proportion of diammonium phosphate resulted in a higher YAN consumption rate during the early stages of fermentation. The yeast strain had a greater effect on the volatiles than the YAN level and composition. Keeping the total YAN constant, a higher proportion of sulfur-containing amino acids resulted in a considerably higher production of 3-methylthiopropanol. The sensory impact of three key volatile sulfur compounds was investigated in a Chardonnay wine matrix, indicating that 3-methylthiopropanol at subthreshold or greater concentrations was effective in enhancing the cantaloupe aroma.

Nitrogen Availability and Utilisation of Oligopeptides by Yeast in Industrial Scotch Grain Whisky Fermentation

Scotch grain whisky is produced with a substantial proportion of unmalted grains, which can result in nitrogen deficiency for yeast in the fermentable grain mash. This study examined nitrogen source availability and utilisation by three commercial whisky strains (Saccharomyces cerevisiae) during Scotch grain whisky fermentation, focusing on oligopeptides. Peptide uptake kinetics in synthetic whisky mash with defined peptides showed that oligopeptides of up to nine amino acids were taken up by the strains, albeit with some variability between the strains. The study found that peptides with appropriate molecular weights could replace free amino acids without negatively affecting fermentation kinetics. Moreover, fermentation performance improved when additional nitrogen was provided via peptides rather than diammonium phosphate. Analysis of industrial grain mash indicated that despite low initial yeast assimilable nitrogen, residual proteolytic activity from malt increased nitrogen availability during fermentation. Approximately 30% of the nitrogen consumed by yeast during grain mash fermentation was derived from peptides. LC-HRMS peptide analysis revealed complex dynamics of peptide formation, degradation, and utilisation. This study highlights the importance of oligopeptides in ensuring optimal fermentation efficiency in Scotch grain mash and similar substrates.

The influence of different methods of under-vine management on the structure of vegetation and the qualitative parameters of the grapes in the Moravian wine region

ABSTRACT The present article explores the importance of vineyard soil management. Studies on under-vine management have yielded a wide range of results, with some indicating potential benefits for vine growth and productivity. However, the methods of under-vine management and their specific effects on vineyard parameters require further research. The aim of this study is to evaluate the relationships existing between the different types of management of under-vine areas and the vegetation grown in this zone and to determine the effects of under-vine management on the yield and quality of Traminer grapevines. By examining various approaches, the research aims to provide insights into the optimising of vineyard management methods to achieve enhanced biodiversity and grape quality in this specific geographical context. The findings indicated that management of the under-vine area can impact the composition of plants, grape yield and quality. Under-row management had an effect on the number of plant species and their composition. The highest weight of bunches was found in MIX (a species from the Fabaceae family), while the lowest was found in the MECH treatment (bare soil). MULCH, MONO and MIX consistently had higher yeast assimilable nitrogen (YAN) in grapes than other treatments. In many of the evaluated parameters, the influence of the seasons was evident.

Insight into the growth and metabolic characteristics of indigenous commercial S. cerevisiae NX11424 at high and low levels of yeast assimilable nitrogen based on metabolomic approach

Yeast assimilable nitrogen (YAN) is one of the important factors affecting yeast growth and metabolism. However, the nitrogen requirement of indigenous commercial S. cerevisiae NX11424 is unclear. In this study, metabolomics was used to analyze the metabolite profiles of the yeast strain NX11424 under high (433 mg/L) and low (55 mg/L) YAN concentrations. It was found that yeast biomass exhibited different trends under different YAN conditions and was generally positively correlated with the initial YAN concentration, while changes of key biomarkers of yeast strain NX11424 at different stages of fermentation showed a similar trend under high and low YAN concentrations. The YAN concentration affected the metabolite levels of the yeast strain NX11424, which resulted in the significant difference in the levels of pyruvic acid, α-oxoglutarate, palmitoleic acid, proline, butane-2,3-diol, citrulline, ornithine, galactinol, citramalic acid, tryptophan, alanine, phosphate and phenylethanol, mainly involving pathways such as central carbon metabolism, amino acid metabolism, fatty acid metabolism, purine metabolism, and energy metabolism. Yeast strain NX11424 could utilize proline to produce protein under a low YAN level. The intracellular level of citrulline and ornithine under high YAN concentration was higher than that under low YAN level. Yeast strain NX11424 is more suitable for fermentation at lower YAN level. The results obtained here will help to rational utilize of YAN by S. cerevisiae NX11424, and is conducive to precise control of the alcohol fermentation and improve wine quality.

Kinetic Evaluation of the Production of Mead from a Non-Saccharomyces Strain.

There is a growing market for craft beverages with unique flavors. This study aimed to obtain a palate-pleasing mead derived from Pichia kudriavzevii 4A as a monoculture. Different culture media were evaluated to compare the fermentation kinetics and final products. The crucial factors in the medium were ~200 mg L-1 of yeast assimilable nitrogen and a pH of 3.5-5.0. A panel of judges favored the mead derived from Pichia kudriavzevii 4A (fermented in a medium with honey initially at 23 °Bx) over a commercial sample produced from Saccharomyces cerevisiae, considering its appearance, fruity and floral flavors (provided by esters, aldehydes, and higher alcohols), and balance between sweetness (given by the 82.91 g L-1 of residual sugars) and alcohol. The present mead had an 8.57% v/v ethanol concentration, was elaborated in 28 days, and reached a maximum biomass growth (2.40 g L-1) on the same fermentation day (6) that the minimum level of pH was reached. The biomass growth yield peaked at 24 and 48 h (~0.049 g g-1), while the ethanol yield peaked at 24 h (1.525 ± 0.332 g g-1), in both cases declining thereafter. The Gompertz model adequately describes the kinetics of sugar consumption and the generation of yeast biomass and ethanol. Pathogenic microorganisms, methanol, lead, and arsenic were absent in the mead. Thus, Pichia kudriavzevii 4A produced a safe and quality mead with probable consumer acceptance.

Efficacy of volatile organic compounds by Aureobasidium pullulans immobilized on hydrogel spheres against strawberry fungal pathogens

AbstractBACKGROUNDThe present study explores the use of two different growth supports for the biocontrol yeasts Aureobasidium pullulans M13, C10, R34 and P17, by use of nutrient yeast glucose (NYDA) agar and hydrogel spheres as the support matrix, then evaluates their impact on the production of volatile compounds (VOCs) and the subsequent in vitro and in vivo antagonistic activity against Botrytis cinerea and Colletotrichum acutatum.RESULTSFor the in vitro assay, VOCs secreted by the isolates C10 and M13 encased in the hydrogel spheres showed greater inhibitory activity on the mycelial growth of B. cinerea (70.30%) and C. acutatum (52.35%), respectively, with respect to NYDA. For solid‐phase microextraction‐gas chromatography‐mass spectrometry, VOCs produced by the selected yeasts immobilized in the hydrogel spheres or cultured in the agar were identified. VOCs were grouped as alcohols, ketones, alkane and aldehyde, with phenylethyl alcohol and 1‐propanol‐2‐methyl being the most prominently produced. The analysis revealed variations in both quantity and composition of VOCs among the growth supports, indicating the hydrogel spheres as enhancer distinct metabolic pathways and substrate utilization of the isolates, particularly in the M13 isolate.CONCLUSIONThe antifungal activity of the VOCs produced in the hydrogel spheres by the isolates C10 and M13 was assessed on strawberries, demonstrating a significant reduction in disease incidences. © 2024 Society of Chemical Industry.

A comparison of free amino nitrogen and yeast-assimilable nitrogen measurement methods for use in alcoholic fermentation of whey

The continued efficient use of whey as a fermentable substrate to produce alcoholic beverages will benefit from improving the measurement of key components relevant to the fermentability of whey. One component of fermentation that is not well studied in whey is the concentration of fermentable nitrogen, either as free amino nitrogen (FAN) or yeast-assimilable nitrogen (YAN). Fermentable nitrogen in media is essential for yeast cells to replicate. Insufficient concentrations of FAN or YAN to support the growing yeast population can result in sluggish or "stuck" fermentations. We evaluated 3 common methods of fermentable nitrogen determination and compared them for use in whey fermentation systems, based on ninhydrin, nitrogen by o-phthalaldehyde (NOPA), and formaldehyde pH (Sørensen titration) values. Each measurement method was evaluated independently using standard addition curves and compared for overall accuracy using paired t-tests (α = 0.05). Although the formaldehyde pH method showed high precision, it did not measure nitrogen accurately, as it overestimated YAN in whey by up to 6 times relative to other tests. The ninhydrin and NOPA methods both showed accuracy for fermentable nitrogen determination in whey based on analysis of standardized nitrogen sources. We concluded that either the ninhydrin FAN or NOPA YAN method may be used to determine the fermentable nitrogen content in whey. This is expected to improve the ability of producers to use whey as a fermentation medium.

The Production of Bioactive Hydroxytyrosol in Fermented Beverages: The Role of Must Composition and a Genetically Modified Yeast Strain

Hydroxytyrosol (HT) is a well-known compound for its bioactive properties. It is naturally present in olives, olive oil, and wine. Its presence in wines is partly due to its production during alcoholic fermentation by yeast through a hydroxylation of tyrosol formed through the Ehrlich pathway. This work aims to explore the influence of yeast assimilable nitrogen (YAN) and glucose content as precursors of HT formation during alcoholic fermentation. Commercial Saccharomyces cerevisiae QA23 and its metabolically engineered strain were used to ferment synthetic must. Each strain was tested at two different YAN concentrations (210 and 300 mg L−1) and two glucose concentrations (100 and 240 g L−1). This work confirms that the less YAN and the more glucose, the higher the HT content, with fermentations carried out with the metabolically engineered strain being the ones with the highest HT content (0.6 mg L−1).

Effects of pesticides on soil bacterial, fungal and protist communities, soil functions and grape quality in vineyards

Abstract Pesticides can have unintentional effects on non‐target organisms and change biotic communities. Such changes might be particularly important in soil microbial communities, which drive many ecosystem functions and may affect crop quality. Here, we investigated, in a three‐year study, how vegetation control (by herbicide application) and soil copper content (from long‐term copper‐based fungicide application) affect biodiversity and the community structure of soil bacteria, fungi and protists, and associated soil functions (respiration, decomposition) in Swiss vineyards. Furthermore, we determined the effects of these two management practices on grape quality as the most direct ecosystem service to farmers. Across all study years, the community composition of microorganisms was affected by herbicide application, however, a significant loss of operational taxonomic units (OTUs) was only observed in fungi and protists. Soil copper content reduced OTU richness of bacteria and protists in some years but had no significant effect on fungal richness. Copper changed the community composition in all three groups of soil microorganisms. While we found no effect of copper on soil functions, herbicide application reduced microbial respiration and biomass by about 39% and 45%, respectively. However, decomposition rates remained virtually unchanged by any pesticide. Yeast assimilable nitrogen (YAN) levels in grape were below the critical threshold of 140 mg/L in 40% of the vineyards without herbicide application and the variety Chasselas, whereas in vineyards with herbicide application, it was only 20%. Application of pesticides led to changes in richness and composition of soil microbial communities and directly reduced some soil functions (microbial biomass and respiration) but not all (decomposition). Some grape quality parameters can be indirectly enhanced by pesticide application, highlighting the trade‐off between the interests of nature conservation and the interests of the farmer. Balancing these two diverging interests requires the establishment of alternative vineyard management allowing reduced pesticide application.

Foliar urea applications to apple trees increase yeast assimilable nitrogen, amino acids, and flavor volatiles in fruit and hard cider

Volatile compounds are a crucial component of hard apple (Malus ✕domestica Borkh.) cider aroma, flavor, and consequent marketability. Amino acids are used by Saccharomyces cerevisiae yeast in the production of volatiles and their precursors. This study hypothesized that foliar applications of nitrogen to apple trees would elevate the concentration of amino acids in the fruit, thus increasing the concentration of sensorially distinguishable aromatic volatiles in cider. In this experiment, urea foliar fertilizer was applied to ‘Ellis Bitter’ and ‘Harry Masters Jersey’ apple trees to create Control (0 applications), Low (3 weekly applications), and High (5 weekly applications) treatments. Total leaf nitrogen increased with the number of foliar urea applications, demonstrating plant uptake. The total fruit yield and fruit efficiency (total harvested fruit mass relative to trunk cross-sectional area) did not differ among treatments within the same cultivar. Similarly, fruit maturity, size, total phenolics, pH, and soluble solids concentration did not differ among treatments. Yeast assimilable nitrogen (YAN) and amino acids in the juice increased with the number of foliar urea applications, as did fermentation rates. Relative to the Control, the High treatment had 130% greater YAN in ‘Ellis Bitter’ and 145% in ‘Harry Masters Jersey’. Over 90% of the YAN in all juice samples was composed of primary amino nitrogen (PAN), and the majority of the PAN among all treatments was asparagine. Ester and fatty acid content in hard ciders increased with the number of urea applications; however, higher alcohols showed a mixed relationship with the number of applications in the cultivar ‘Ellis Bitter’. Aroma and flavor differences among treatments were discernible by triangle discrimination test panelists; however, the specific sensory differences were not easily identifiable with untrained panelists. This study demonstrated that late season foliar urea applications to apples trees can increase juice YAN and aromatic compounds in finished cider.

Adapting service crop termination strategy in viticulture to increase soil ecosystem functions and limit competition with grapevine

Soil management and particularly service crops are a promising solution for addressing current challenges in viticulture as they limit the use of herbicides while increasing potential ecosystem services. Scientific literature barely considers the importance of service crop management to reach trade-offs between ecosystem services and disservices. This study evaluates during a three-year experiment, 6 service crop termination strategies for winter service crops, combining two service crops termination periods (early termination in February vs. termination at grapevine budburst) and three termination methods (mower (M), mower + tillage (T), roller-crimper (R)). Service crop (biomass, C:N ratio, weeds, and mulch following termination), soil ( soil organic matter, microbial biomass, and water and nitrogen stocks), and grapevines (predawn leaf water potential, yield components, δ13C, yeast assimilable nitrogen in juice, and pruning weight) were monitored from 2019 to 2022. Allowing service crops to develop until the budburst of the vine resulted in a two to three-fold increase in biomass compared to early destruction. Termination involving soil tillage was the most effective method, as treatments destroyed early with soil tillage exhibited almost no regrowth. Soil tillage termination led to the lowest biomass of weeds at the grapevine flowering two years out of three, and prevented the regrowth of certain sown plants, especially Poaceae. The roller was less effective in destroying service crop species but was the best method for maintaining plant residues on the soil surface. A higher soil microbial biomass was observed with termination at budburst, combined with no-till termination methods. Termination involving soil tillage was notably more effective in stopping service crop transpiration, increasing soil water stocks and improving grapevine water status. In 2020 and 2022, soil inorganic nitrogen stocks were almost 4 times higher in the T treatments compared to the other two termination methods, achieving a level of approximately 61 kg ha−1 that closely corresponds to the annual nitrogen requirements of grapevines. The yeast-assimilable nitrogen (YAN) content in grape juice mirrored this trend. Pruning weight varied significantly between different termination methods, with T treatments exhibiting a higher pruning weight per vine in comparison to R and M treatments. In general terms, the T treatment had a significantly higher number of bunches, the M treatment had the lowest, and the R treatment exhibited intermediate values. Overall, the average grapevine yield ranged from 7.25 to 13.7 t ha−1, corresponding to 52–98 hL ha−1 (with 4000 vines ha−1, 140 kg hL−1). This level of production may be accepted for Protected Designations of Origin that limit grapevine yield to 40 or 60 hL ha−1, but it could be a limitation for Protected Geographical Indications, which permit 90 hL ha−1, or unlabeled productions without yield limitations. Given the Mediterranean climate context, with rising frequencies of dry winters due to climate change, termination involving soil tillage appears to be the least risky strategy to preserve grapevine vigor and production while improving soil-based ecosystem functions. However, this might be contingent on the targeted yield and wine valuation.

Fermentation Process Effects on Fermented McIntosh Apple Ciders

This research is the first study of McIntosh apple cider fermentation using different must treatments. The must materials included standard pressed juice, the common cider fermentation material, mash, direct from the apple shredder both with and without pectinase additions, and finally, pomace. These four treatments caused multiple differences from the standard hard ciders from juice, starting with the apple must characteristics, following through the yeast fermentation processes, and carried into the final ciders. Initial apple musts had different sugar content, pH, acids, total phenolics, and antioxidant activities. Although juice contained more total phenolics and had more antioxidant capabilities, it contained lower levels of yeast assimilable nitrogen. The sugar consumption dynamic changes had a differential dynamic trend but did not alter the capacity for complete apple cider fermentation. From the fermentation color dynamic changes, it indicated that must materials would have effects on color-changing amplitudes. Juice treatment had the largest changes from the must. Pomace and mash with pectinase had fewer color changes in multiple color values (L*, a*, b*). The mono phenolics in the final cider indicated that pomace ferments contained the least hydroxycinnamates but a similar amount of total flavanols as juice-fermented ciders. Cider from the juice contained the least flavonols, whereas the mash, both with and without pectinase treatments, had the largest amount of flavonols. This work will provide some applicable information for apple cider fermentation from the apple wastes in the cider industry.

Impact of phenylalanine on Hanseniaspora vineae aroma metabolism during wine fermentation

Hanseniaspora vineae exhibits extraordinary positive oenological characteristics contributing to the aroma and texture of wines, especially by its ability to produce great concentrations of benzenoid and phenylpropanoid compounds compared with conventional Saccharomyces yeasts. Consequently, in practice, sequential inoculation of H. vineae and Saccharomyces cerevisiae allows to improve the aromatic quality of wines. In this work, we evaluated the impact on wine aroma produced by increasing the concentration of phenylalanine, the main amino acid precursor of phenylpropanoids and benzenoids. Fermentations were carried out using a Chardonnay grape juice containing 150 mg N/L yeast assimilable nitrogen. Fermentations were performed adding 60 mg/L of phenylalanine without any supplementary addition to the juice. Musts were inoculated sequentially using three different H. vineae strains isolated from Uruguayan vineyards and, after 96 h, S. cerevisiae was inoculated to complete the process. At the end of the fermentation, wine aromas were analysed by both gas chromatography–mass spectrometry and sensory evaluation through a panel of experts. Aromas derived from aromatic amino acids were differentially produced depending on the treatments. Sensory analysis revealed more floral character and greater aromatic complexity when compared with control fermentations without phenylalanine added. Moreover, fermentations performed in synthetic must with pure H. vineae revealed that even tyrosine can be used in absence of phenylalanine, and phenylalanine is not used by this yeast for the synthesis of tyrosine derivatives.

Non-Saccharomyces yeast derivatives: Characterization of novel potential bio-adjuvants for the winemaking process

Winemakers have access to a diverse range of commercially available Inactivated Dry Yeast Based products (IDYB) from various companies and brand names. Among these, thermally inactivated dried yeasts (TIYs) are utilized as yeast nutrients during alcoholic fermentation, aiding in the rehydration of active dry yeasts and reducing ochratoxin A levels during wine maturation and clarification. While IDYB products are generally derived from Saccharomyces spp., this study investigates into the biodiversity of those deriving from non-Saccharomyces for potential applications in winemaking. For that S. cerevisiae and non-Saccharomyces TIYs were produced, characterized for nitrogen and lipid content using FT-NIR spectroscopy, and applied in a wine-like solution (WLS) for analyzing and quantifying released soluble compounds. The impact of TIYs on oxygen consumption was also assessed. Non-Saccharomyces TIYs exhibited significant diversity in terms of cell lipid composition, and amount, composition, and molecular weight of polysaccharides. Compared to that of S. cerevisiae, non-Saccharomyces TIYs released notably higher protein amounts and nHPLC-MS/MS-based shotgun proteomics highlighted the release of cytosolic proteins, as expected due to cell disruption during inactivation, along with the presence of high molecular weight cell wall mannoproteins. Evaluation of antioxidant activity and oxygen consumption demonstrated significant differences among TIYs, as well as variations in GSH and thiol contents. The Principal Component Analysis (PCA) results suggest that oxygen consumption is more closely linked to the lipid fraction rather than the glutathione (GSH) content in the TIYs. Overall, these findings imply that the observed biodiversity of TIYs could have a significant impact on achieving specific oenological objectives.

A First Report on the Isolation and Characterization of a Highly Potential Indigenous Mosquitocidal Bacterium (Bacillus thuringiensis Subspecies Israelensis VCRC B647) from Red Soil, India.

To control mosquito vectors causing human diseases, bacterial biopesticides are currently in use. Indeed, the recent development of resistance to these bacterial agents has impeded its applications. Under these circumstances, the search for novel bacterial agents with mosquitocidal activity is unavoidable. In this study, a novel mosquitocidal bacterium was isolated from red soils of agricultural field. The objective of this study was to isolate and identify new mosquitocidal bacteria from the natural environment. Soil samples were collected during 2021-2022 from Tirupathur district of Tamil Nadu, South India. The samples were bioprocessed for culturing the bacterial colony in a suitable culture medium (Nutrient Yeast Salt Medium), and after 72 h, the bacterial cell mass was removed and lyophilized. Bioassays (mosquito toxicity assays) were carried out to screen the bacterial colonies for mosquitocidal effect. The potential colony was further analyzed, and identified for its application in mosquito control. The new isolate screened from red soil was identified as Bacillus thuringiensis subspecies israelensis (VCRC B647) as per the ilvD gene sequence analysis. The strain was found to be potentially effective in controlling mosquito larvae, and further biochemical analyses, bacterial growth, biomass, and protein content were investigated. The new isolate did not show any toxic effect on nontarget aquatic organisms. It is significant to depict that the mosquitocidal action of this new isolate (Bti) is highly significant than the reference strain of Bti-H14. It is concluded that this is the first report that an indigenous strain of Bti VCRC B647 is very effective in mosquito control.