Search Results (19)

The increasing volume of discarded apples generated by commercial grading standards and postharvest losses represents both an environmental burden and an opportunity for sustainable valorization. Despite growing interest in circular economy strategies in the fruit-processing sector, a comprehensive review of the technological, microbiological, and nutritional factors influencing cider production from discarded apples remains limited. To address this gap, this review discusses key aspects of cider production from discarded apples, focusing on raw material characterization, nutrient management, yeast strategies, and fermentation technologies. The physicochemical and microbiological properties of discarded apples are examined, including soluble solids, acidity, phenolic composition, and microbial spoilage risks. Special attention is given to nutrient optimization, particularly yeast assimilable nitrogen (YAN), vitamins, and minerals, as deficiencies may cause sluggish fermentation and adversely affect volatile compound formation and stability. This review evaluates yeast selection, comparing Saccharomyces cerevisiae with non-Saccharomyces yeasts and mixed fermentations, highlighting their effects on chemical composition, aroma, and sensory quality. Innovative approaches such as yeast immobilization and repeated-batch fermentation are reviewed as tools to improve process performance. Key technical challenges, including variability in raw material quality, nutrient supplementation needs, contamination risks, and process scalability, are discussed alongside opportunities for valorization of cider pomace within a circular economy framework. Full article

This narrative review develops fermentation-oriented viticulture as an agronomic-oenological framework linking vineyard environment, management and must ecology to fermentation performance. The literature from 2010 to April 2026 was synthesized through structured searches in PubMed and Google Scholar, complemented by targeted searches in MDPI, Frontiers, Nature, ScienceDirect, OENO One, PNAS and European Union regulatory sources, with emphasis on 2020–2026 publications and retention of older foundational sources. Current evidence indicates that must microbiota is not a linear derivative of soil or berry surfaces, but a network outcome of connected habitats spanning the viticultural biotope and grapevine-associated biocenosis (soil, rhizosphere, phyllosphere, berry, insect, atmospheric and winery). Climate warming, drought, altered phenology, soil fertility, nitrogen nutrition, crop-protection programs and bio-based inputs jointly modify berry chemistry, yeast-assimilable nitrogen (YAN), microbial inocula and pre-fermentative selection pressures. The review distinguishes fermentation-oriented viticulture from descriptive microbial terroir by defining practical endpoints: fermentation onset and completion, sluggish or stuck fermentation risk, microbial stability, spoilage taxa, volatilome development and wine typicity. It also proposes operational indicators and a decision matrix for integrating vineyard and winery management. The framework supports future multi-vintage studies combining climate, soil, agronomic metadata, YAN, microbiome profiling and microvinification outcomes. Full article

This study aimed to determine the effects of diammonium phosphate (DAP) and yeast autolysates (organic nutrients) added during alcoholic fermentation on the content and profile of aroma compounds in Sauvignon Blanc wines. Sequential additions of either DAP or organic nutrients were applied mainly during the first half of fermentation, increasing yeast assimilable nitrogen (YAN) from an initial 124 mg N/L to final concentrations of 208 and 209 mg N/L for DAP and yeast autolysates, respectively. Control musts were fermented without nutrient supplementation. All treatments were fermented using commercial yeast strain. Varietal thiols, ethyl and acetate esters, higher alcohols, glutathione (GSH), and YAN were monitored at early, mid, and late stages of fermentation, as well as in the final wines. Varietal thiols were formed at early stages of fermentation in all treatments; however, concentrations of both 4-methyl-4-sulfanylpentan-2-one (4MSP) and 3-sulfanylhexan-1-ol (3SH) were higher in wines supplemented with organic nutrients comparing to DAP and control. Compared to the control, DAP and organic nutrient supplementation increased ethyl ester concentrations in wine by 40.2% and 26.9%, respectively. Both nutrient treatments also resulted in higher acetate ester concentrations, while total higher alcohols were reduced by 19.1% with DAP and 12.1% with organic nutrients. No significant differences in GSH concentrations were observed among treatments. Sensory analysis revealed that wines supplemented with DAP achieved the highest scores for tropical aroma, varietal aroma, and overall quality. Overall, sequential supplementation with either inorganic or organic nitrogen positively influenced fermentation kinetics and aroma compound composition, resulting in improved varietal expression of Sauvignon Blanc wines. However, in low-YAN musts, DAP had a greater impact than organic nitrogen sources and should therefore be considered a key strategy for ensuring an adequate yeast nitrogen status. Full article

This study examined how different fertilisation strategies (mineral, compost, vermicompost and non-fertilised control) influence vine nutrient status, must composition and wine chemical characteristics over two consecutive seasons (2024–2025) in two semi-arid Mediterranean vineyards, one deficit-irrigated and other rainfed. Compost and vermicompost were produced from winery residues, in line with a circular management approach. Organic fertilisation improved vine nitrogen and potassium levels, particularly at veraison, with cumulative effects observed over time. Musts from fertilised vines (mineral, compost and vermicompost) exhibited higher levels of yeast-assimilable nitrogen (YAN) and pH, as well as lower titratable acidity, compared to the control group (without fertilization). Wines obtained from these treatments exhibited higher ethanol content and modified acidity parameters, with compositional changes being more evident in the rainfed vineyard. Analysis of volatile compounds revealed that organic fertilisers, particularly vermicompost, promoted the formation of esters, higher alcohols, and terpenes linked to grape metabolism and fermentation. These results demonstrate that organic amendments derived from winery waste can serve as efficient nutrient sources, thereby enhancing the nutritional balance of vines and the composition of wines, while also promoting sustainable and circular practices in viticulture. Full article

Foliar application of fertilizers and bioactive compounds helps viticulture adapt to climate change, while biochar (BC) derived from grapevine pruning residues (GPRs) represents a versatile material that further contributes to climate change mitigation. In this study, the foliar application impact of seven different formulations on the chemical composition and quality of must and wine of Malvazija istarska (Vitis vinifera L.) was investigated. The suspensions contained various combinations of BC, urea, and amino acids. BC increased the pH of the solutions in which it was present due to its alkaline nature, thereby influencing the uptake of nutrients and other compounds. Treatments C (control) and A (amino acids) led to the highest amount of yeast-assimilable nitrogen (YAN) (170 and 172 mg N/L). The amino acid profile of the must differed from the typical composition, with glutamine identified as the predominant compound. The combination of BC with urea and amino acids was associated with a higher sugar concentration in the must compared to the application of BC alone, ranging from 208 to 223 g/L. Combining BC with other components led to wines that received superior sensory evaluation scores compared to both C and B. BC alone did not influence must or wine quality. However, its application in combination with other components makes it a suitable carrier for such compounds. Due to its benefits, easy and cheap production, foliar application of BC suspensions with fertilizers can become a standard operation in viticulture and contribute to sustainable fertilization. Full article

This study examined the impact of five grapevine rootstocks (R110, 140Ru, 3309C, 41B, and FERCAL) on must composition, nitrogen status, and sensory attributes of Vitis vinifera L. cv. Assyrtiko wines. Vines were grown under uniform vineyard conditions, and microvinifications were conducted consistently across treatments. Rootstock genotype significantly influenced Baumé, density, titratable acidity, pH, and yeast-assimilable nitrogen (YAN). Musts from R110 contained the highest YAN (226.80 ± 0.99 mg/L) and intermediate Baumé (12.5°), whereas 140Ru exhibited the lowest YAN (132.60 ± 0.46 mg/L) and Baumé (11.7°). Wines from R110 contained the highest tannin concentration (0.375 g/L), while FERCAL produced the highest ethanol content (13.1% vol). Sensory evaluation revealed significant rootstock effects on color intensity, aroma intensity, aroma complexity, balance, and overall quality, with R110 and 3309C receiving the highest scores. The findings demonstrate that rootstock selection may affect the chemical and sensory profile of Assyrtiko wines, providing a practical tool for optimizing wine style and quality across diverse viticultural environments. Further research is needed to confirm these findings and explore extra parameters and novel rootstock–scion interactions. Full article

This study evaluates the agronomic potential of two types of vermicompost—one produced solely from wine industry residues (WIR) and one incorporating sewage sludge (WIR + SS)—under rainfed and deficit irrigation conditions in Mediterranean vineyards. The vermicompost was obtained through a two-phase process involving initial thermophilic pre-composting, followed by vermicomposting using Eisenia fetida for 90 days. The conditions were optimized to ensure aerobic decomposition and maintain proper moisture levels (70–85%) and temperature control. This resulted in end products that met the legal standards required for agricultural use. However, population dynamics revealed significantly higher worm reproduction and biomass in the WIR treatment, suggesting superior substrate quality. When applied to grapevines, WIR vermicompost increased soil organic matter, nitrogen availability, and overall fertility. Under rainfed conditions, it improved vegetative growth, yield, and must quality, with increases in yeast assimilable nitrogen (YAN), sugar content, and amino acid levels comparable to those achieved using chemical fertilizers, as opposed to the no-fertilizer trial. Foliar analyses at veraison revealed stronger nutrient uptake, particularly of nitrogen and potassium, which was correlated with improved oenological parameters compared to the no-fertilizer trial. In contrast, WIR + SS compost was less favorable due to lower worm activity and elevated trace elements, despite remaining within legal limits. These results support the use of vermicompost derived solely from wine residues as a sustainable alternative to chemical fertilizers, in line with the goals of the circular economy in viticulture. Full article

Amino acid composition and nitrogen quantification in grape must are of great importance given their usefulness for varietal characterization, influence on fermentation processes and identification of the aromatic potential of musts. The objective of this work was to determinate the amino acid and nitrogen compound profiles of 30 minority varieties of potential use in winemaking, all grown in the same ampelographic collection in Alcalá de Henares. The concentrations of 31 amino acids in must were identified and quantified using high-performance liquid chromatography (HPLC) during four seasons (2020 to 2023), and the average values of total free amino acids (TAN), yeast assimilable nitrogen (YAN) and aromatic precursor nitrogen (APN) were calculated for each variety. ‘Tazazonal’, a minority red grape variety, was found to exhibit high concentrations of yeast assimilable nitrogen (YAN), total amino nitrogen (TAN) and ammonia nitrogen (APN), comparable to those observed in ‘Tempranillo’ and ‘Garnacha Tinta’. These two cultivars are representative of traditional Spanish red grapevine varieties and are among the most widely cultivated in the country. In the case of white varieties, ‘Albillo del Pozo’, ‘Pintada’ and ‘Verdejo Serrano’ showed higher concentrations of these parameters than ‘Malvar’ and ‘Airén’, which are also widely grown in Spain. The results revealed distinct amino acid profiles for each variety, enabling their classification and supporting the identification of variants within the autochthonous germplasm. This approach aimed to highlight minority varieties of potential interest for future studies, given their relevance to both regional and national viticulture. Full article

Ten vineyards, belonging to five wine regions, were selected in this study. Maturity indicators and phenolic and aromatic compounds were measured to investigate relationships with factors related to the terroir, including climate conditions and soil nutrients. Multiple factor analysis of all compositions showed that different wine regions or vineyards had different characteristics, which were partly associated with the terroir. The results showed that Shizuishan had high sugar content. A high level of anthocyanins could be found in Qingtongxia and Yongning, respectively. Moreover, Qingtongxia had higher concentrations of monomeric phenols in grapes than the others. LSYH (Lanshanyunhao) and LL (Lilan) had higher YAN (yeast assimilable nitrogen) content and pH in grapes, but their wine had a green flavor (high concentration of alcoholic volatile compounds). The Shizuishan and Hongsipu wine regions had fruitier flavors (high concentration of ester volatile compounds). This study demonstrated the characteristics of different vineyards and wine regions, providing a direction for the future development of region-specific grapes and wines. Full article

Drama represents one of the distinct winegrape regions in the continuous growth of northern Greece. Yet, little is known about grape, must, and wine quality in various parts of the region. Determining the physicochemical characteristics of the Merlot, Cabernet Sauvignon, and Agiorgitiko grape varieties grown in different locations in the area across two vintages, their chromatic characteristics, phenolic profile, and organoleptic characteristics were the goal of this study. The results reveal a high variation in the physicochemical characteristics of must and wine among the locations. The location affects the profile of phenolic compounds with procyanidin B2, catechin, procyanidin B3, procyanidin B1, epicatechin, and gallic acid being present in high amounts. Merlot wines from the location with the highest altitude showed a higher amount of quantified phenolics. Altitude positively affected the yeast assimilable nitrogen (YAN) levels and negatively the wine’s purple hue. Moreover, the grape weight negatively affects the levels of some of the quantified phenolic compounds. On the other hand, both altitude and YAN positively impact the taste of wines. The altitude represents a significant parameter in the location studied that influences the quality parameters and taste of the wines. As part of climate adaptation strategies for viticulture in the Drama region and other comparable regions, high-altitude vineyard development should be studied to preserve the grape’s acidity and counteract warming trends. Full article

All traditional mezcal producers use artisan methods to produce mezcal. The low technological development in the elaboration processes results in low yield and high residual sugar concentration. First, this work optimized the concentration of initial sugars and yeast-assimilable nitrogen (YAN) in Agave durangensis juice fermentation at the laboratory level. A yield near 0.49 g EtOH/g sugar and a productivity of 1.54 g EtOH/L*h was obtained with an initial sugar concentration of 120 g/L and a YAN concentration of 0.227 g/L. Only Saccharomyces cerevisiae was found after 24 h of incubation at laboratory level, using MALDI-TOF identification. Agave durangensis heads crushed by the artisan process were used to test the inoculant performance. A mezcal yield of 11.6 kg agave/L of mezcal was obtained using the S cerevisiae inoculant and nitrogen addition, which was significantly different (p < 0.05) from other treatments. The population dynamics during fermentation were analyzed through isolation and identification using MALDI-TOF. Several yeast species (Pichia kluyveri, Torulaspora delbrueckii, Zygosaccharomyces bailii, and Saccharomyces cerevisiae) were found at the beginning of fermentation. Nonetheless, only S. cerevisiae was found at the end of fermentation. The implantation of the inoculant used was confirmed through the comparative analysis of amplification patterns of the GTG5 microsatellite of the strains identified as S. cerevisiae, finding that the inoculated strain proportion was greater than 80% of the yeast population. A technological alternative to increase the efficiency of the process is combining the addition of YAN and the inoculation of the native S. cerevisiae, which was isolated from artisan alcoholic fermentation of agave to produce mezcal. Full article

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). Full article

The influence of yeast assimilable nitrogen (YAN) and elemental sulfur (S⁰) on the formation of volatile sulfur compounds (VSCs) during fermentation was investigated. Pinot noir fermentations were performed using Saccharomyces cerevisiae strain UCD522 or P1Y2 with an addition of 0, 5, or 15 µg/g elemental sulfur. H₂S production during fermentation was measured using lead acetate tubes and additional VSCs measured by GC-PFPD. The addition of S⁰ resulted in H₂S formation during alcoholic fermentation regardless of which yeast strain was used. H₂S production was greater in fermentations performed by UCD522 with increasing amounts of S⁰ resulting in increased production of H₂S. Higher S⁰ resulted in wines containing higher concentrations of methyl thioacetate and glutathione disulfide. Additional experiments examined the impact of nitrogen composition and S⁰. The addition of diammonium phosphate (DAP) resulted in an increase in H₂S formation during fermentation whereas the addition of amino acids did not, whether S⁰ was added or not. Fermentations where DAP and S⁰ were both added produced a higher concentration of H₂S compared to fermentations where S⁰ or DAP additions were made individually. VSCs in the wine were also impacted by the addition of nitrogen and/or S⁰ with the addition of S⁰ and nitrogen (DAP or amino acids) resulting in elevated concentrations of methyl thioacetate in the wines. Full article

Yeast assimilable nitrogen (YAN), besides the oenological parameters (sugar content, titratable acidity, and pH) in grape musts of sixteen native and international varieties of Vitis vinifera cultivated in six regions of Northern Greece, was assessed in the frame of the present study. Low levels of YAN are frequently thought to be the cause of problematic fermentations and originate significant changes in the organoleptic aspects of the finished product. The objective of this multi-variety study was to assess factors affecting the YAN amount and composition in technologically mature grapes and, therefore, to evaluate the necessity of YAN supplementation with ammonium salts in musts across different native and international grape varieties. Free amino nitrogen was measured colorimetrically, ammoniacal nitrogen was measured enzymatically, and their values for each must sample were summed to obtain the total amount of YAN. Statistical analysis was carried out including principal component analysis (PCA) to discover relationships among must samples and the parameters studied. PCA analysis classified samples depending on grape varieties and region of origin, bringing knowledge about native and international cultivars of great commercial interest. Moreover, these findings could help to understand how commercial varieties can behave in different climates in the climate change context. Full article

One of the challenges that European agriculture will have to face will be to adapt conventional agriculture to procedures of the new European agricultural policies. In this way, organic farming will have more importance in the coming years. One of the most important crops worldwide is grapevine. The main objective of this research work focuses on the physiological, agronomic, and enological characterization of Pedro Ximénez with the purpose of knowing the viability of the organic cultivation of this cultivar in a warm climate zone. Two experimental plots were selected with two different types of management, organic and conventional. In both plots, photosynthetic capacity (A_N), stomatal conductance (g_s), and intrinsic water-use efficiency (WUE_i) were measured, and physicochemical composition of grape must was analyzed during ripening. In addition, bunch and pruning weight were measured as agronomic parameters. Physiological results were not significantly different between management at a general level in g_s and WUE_i, being possible to identify a difference in A_N just before the harvest. At the level of fruit ripening, significant differences were found between the two managements. At harvest, grape must had a higher sugar concentration, amine nitrogen (α-NH₂), and yeast assimilable nitrogen (YAN) in the organic management than in conventional, where higher values of pH and l-malic acid were observed. Taking into account the preliminary results obtained it could be concluded the viability of the organic management for Pedro Ximénez crop in a warm climate zone. Full article