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Non-Saccharomyces yeasts, particularly Metschnikowia pulcherrima, are considered alternatives to SO2 in winemaking, combating specific microorganisms. The sensory profile of the wine is contingent upon the type of yeast, the fermentation conditions, and the concentration and mode of application with Saccharomyces cerevisiae strains (whether pure or used in mixed/sequential co-fermentation). This study assessed the aroma in red wines produced with S. cerevisiae (Sc) and M. pulcherrima (Mp, non-Sc), incorporating variations in the method of addition and the inclusion or exclusion of SO2. The enological parameters of the wines were slightly affected. Volatile compounds were analysed in the wines through gas chromatography–mass spectrometry (GC-MS) at three moments: at the end of malolactic fermentation (MLF) and after 6 and 9 months of bottle ageing. Sequential fermentation of Sc and Mp reduced the concentration of most identified alcohols and acids, which is favourable, as these compounds can yield undesirable aromas at high concentrations. Regardless of the yeast mixture and Mp dose, a majority of the acetate esters and ethyl esters were quantified at concentrations above their perception thresholds, thus enhancing the sensory quality of the wines. Sensory analysis of wines showed generally positive evaluations. Using non-Saccharomyces as an alternative to SO2 improves the aromatic profile of wines.

The knowledge of volatile compounds concentration in grape berries is very valuable information for the winemaker, since these compounds are strongly involved in the final wine quality, and in consumer acceptance. In addition, it would allow to set the harvest date according to aromatic maturity, to classify grape berries according to their quality and to make wines with different characteristics, among other implications. However, so far, there are no tools that allow the volatile composition to be measured directly on intact berries, either in the vineyard or in the winery.

Foliar nutrient sprays are broadly used in commercial agriculture. To date, the application of Ca and Si has been little explored in vineyard production but may lead to positive responses at various levels. Therefore, the aim of this work was to evaluate the effect of supplying single or combined calcium (Ca, 120 mM) and silicon (Si, 120 mM) sprays in Tempranillo grape composition. Foliar treatment with Ca + Si foliar enhanced all families of aromatic compounds, whereas single Ca and Si sprays induced lower effects. Regarding phenolic compounds, all foliar treatments led to minor effects. However, all three foliar Ca and Si treatments increased the total grape amino acid content. Consequently, the application of combined Ca and Si sprays to a vineyard is recommended as a tool for improving grape quality.

Spectral instruments can be useful for the rapid assessment of chemical compounds in different targets, and their use have been already reported for the modeling of grape composition comparing two spectral ranges. Still, with the increased easiness of acquiring data with several sensors, it would be valuable to explore spectral fusion techniques for the modeling with deep learning, seeking to obtain improved performance. Therefore, the objective of this work was to develop multi-sensor spectral fusion approaches for the deep learning modeling of grape composition. From 128 grape samples, two spectra per sample were acquired from two different ranges using two sensors (visible and shortwave near infrared, 570–1000 nm; and wider NIR 1100–2100 nm). From each sample, 15 grape nitrogen compounds were analyzed by wet chemistry. Three different data fusion approaches are defined using neural networks and deep learning, testing several ways of structuring and merging the input spectra. Statistical analyses supported that (i) the proposed deep learning fusion architectures performed better than single spectral range models, and (ii) neural networks have better modeling capabilities than partial least squares in spectral fusion. The results demonstrate the potential of deep learning for spectral data fusion in grape nitrogen composition regression, and potentially other traits in food and agriculture spectroscopy.

Tools to address the mismatch between technological and phenolic maturity of grapes are needed. Application of elicitors could be an effective alternative. This work compares the effect of the application of methyl jasmonate (MeJ) in conventional form and, as a novelty, in the form of MeJ-doped nanoparticles (ACP-MeJ) on the phenolic composition of Tempranillo grapes. Results showed that, regardless of season, both treatments increased the grape total phenols content. In 2019, most of the anthocyanins, and to a lesser extent the flavanols, increased with the application of MeJ, and several hydroxycinnamic acids increased in the grapes treated with ACP-MeJ, with dose 10 times lower than those of the MeJ conventional. In 2020, anthocyanins were not affected by the treatments, but total flavanols, flavonols, hydroxybenzoic acid, and stilbenes increased after ACP-MeJ application. Thus, foliar application of ACP-MeJ could serve to increase grape phenolic composition, reducing maturity decoupling and the environmental impact.

Background and goals The aim of this work was to study, for the first time, the influence of foliar application of methyl jasmonate (MeJ) and methyl jasmo-nate plus urea (MeJ+Ur) on Tempranillo grape phenolic composition over two seasons. Methods and key findings This work examined grape phenolic compounds usi ng hi gh-per f or mance l i qui d chromatography-diode array detection. In 2019, both treatments increased the total anthocyanins, but the MeJ+Ur treatment had a stronger effect than the MeJ treatment. MeJ foliar application decreased total flavonols, total flavanols, and total hydroxycinnamic acids in the grapes, while MeJ+Ur significantly decreased total flavonols, but did not affect total flavanol s or hydroxyci nnami c aci ds. Neither of the foliar treatments affected total stilbenes. However, in 2020, the effect of treatments was different: foliar treatments did not affect the anthocyanins, flavonols, hydroxyci nnami c aci ds, or sti l benes, but increased the flavanol content in the grapes. Conclusions and significance The effect of foliar treatments was season-dependent, which can be explained by the differences in preharvest rainfall between vintages. The influence of season on grape phenolic compounds was greater than that of the treatments. The results offer information about the response of grapevine to foliar application under different climate conditions.

In recent years, foliar application of elicitors to the vineyard has been increasingly used, in particular, elicitation with methyl jasmonate (MeJ). However, due to the high cost of this compound, it is necessary to find a form of application in which the amount to be used is considerably reduced. Therefore, the aim of this work was study for the first time the influence of foliar application of nanoparticles doped with MeJ (ACP-MeJ) and foliar application of methyl jasmonate (MeJ), using a dose of 1 mM versus 10 mM, respectively, on volatile composition of Tempranillo grapes during two consecutive vintages. Grape volatile composition was determined by SPME-GC-MS. The obtained results reveal that MeJ application increased the concentration of terpenoids, and total C6 compounds in 2019 and 2020, and C13 norisoprenoids in 2019. In addition, ACP-MeJ enhanced the amount of terpenoids, and benzenoids in 2020. These are encouraging results considering that the ACP-MeJ dose was 10 times lower than that of MeJ. Therefore, the foliar application of MeJ supported on nanoparticles could be a tool in order to improve grape volatile composition, favoring a more viable and sustainable viticulture.

Nanoparticles are emerging as a cutting-edge technology to improve crop agricultural input efficiency and reduce biotic and abiotic stresses. In viticulture, nanoparticles hold promise for the sustainable application of an elicitor (methyl jasmonate, MeJ), allowing a considerable dosage reduction. Herein, the influence of the foliar application of free MeJ (10 mM) and MeJ nanoformulation (ACP-MeJ, 1 mM MeJ) on Tempranillo grape amino acids content over two vintages (2019 and 2020) was evaluated. While both MeJ treatments provided a significant increase of the amino nitrogen and yeast assimilable nitrogen in the must in 2019, there were no significant differences on these parameters in 2020. In 2019, MeJ treatment enhanced the synthesis of most of the amino acids included in this study, while ACP-MeJ promoted the formation of six amino acids. Hence, the content of total amino acids, with and without proline, was higher after applying MeJ than in the control musts. However, these values were higher for control must than for MeJ samples in 2020. The multivariable analysis confirmed that the vintage factor had a more prominent effect on the overall parameters of the musts. This strong influence of the vintage could be related to the higher rainfall in 2020.

BACKGROUND: Grape aromas are formed by a great number of volatile compounds. Methyl jasmonate (MeJ) and urea (Ur) foliar applications have been studied to improve grape quality, but their combined application has never been studied. RESULTS: In both seasons, MeJ application enhanced terpenoids and C6 compounds synthesis, though decreased alcohols content. Moreover, MeJ + Ur treatment reduced benzenoids and alcohols and did not affect C-norisoprenoids content. However, there was no clear effect of these treatments on the rest of the volatile compounds. Multifactorial analysis showed a season effect on all volatile compounds, except terpenoids. Discriminant analysis showed a good separation among samples under treatment criterion. The great effect of MeJ treatment on terpenoids was probably due to this elicitor influencing their biosynthesis. CONCLUSION: Season has a strong influence on grapes aromatic composition since it affects all volatile compound families except terpenoids. MeJ foliar application enhanced terpenoids, C-norisoprenoids and C6 compounds synthesis, whereas decreased alcohols content; however, MeJ + Ur foliar treatment did not affect C-norisoprenoids and C6 compounds, and decreased benzenoids and alcohols grape compounds. Therefore, no synergistic effect was observed between Ur and MeJ on grape volatile compounds biosynthesis. Foliar application of MeJ seems to be sufficient to improve the aromatic quality of grapes. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Methyl jasmonate (MeJ) is an elicitor that, when applied in the vineyard, can improve grape quality. There are several studies about the MeJ influence on red grape varieties; however, to our knowledge, there is little information about white grape varieties, specifically Tempranillo Blanco. Therefore, the aim of this work is to evaluate the effect of MeJ foliar treatments, carried out at veraison and post-veraison, on the aromatic, phenolic and nitrogen composition of Tempranillo Blanco grapes. The results showed that grape volatile compounds content increased after MeJ application, especially terpenoids, C13 norisoprenoids, benzenoids and alcohols, and, in general, mainly at post-veraison. Regarding phenolic and nitrogen compounds, their concentrations were enhanced after MeJ treatments, regardless of application time. Consequently, MeJ treatment improved grape volatile, phenolic and nitrogen composition, particularly when this elicitor was applied post-veraison. Therefore, this is a good and easy tool to modulate white grape quality.

La composición volátil de la uva es uno de los parámetros más importantes para determinar la calidad del mosto y del vino. Los aromas de la uva, también llamados primarios, se dividen en aromas varietales y prefermentativos. Estos compuestos se encuentran en muy bajas concentraciones en la uva, por lo que, para llevar a cabo su identificación y cuantificación, se requiere de un método eficaz de extracción para su posterior análisis cromatográfico. El análisis de compuestos volátiles de las uvas mediante métodos cromatográficos presenta numerosos inconvenientes, como el consumo de tiempo, la pérdida de muestra y preparación de la misma, los costes de reactivos e instrumentación y la necesidad de personal formado, por lo que estos equipos solo están disponibles en algunos centros de investigación y en grandes bodegas. Actualmente no existe ningún método que permita realizar análisis rutinarios a tiempo real de la composición aromática de las uvas a lo largo de su maduración, hecho que le permitiría al viticultor tomar decisiones respecto a las prácticas vitícolas, a la elección de la fecha de vendimia o a la clasificación de la uva en función de su calidad aromática. Este hecho ha cobrado mayor importancia en los últimos años debido al desequilibrio entre la madurez industrial (contenido de azúcares/ácidos) y las madureces fenólica y aromática en la uva, provocado por el efecto del cambio climático. Como consecuencia del mismo, las bayas alcanzan más rápidamente el contenido adecuado de azúcares (medidos como sólidos solubles totales (TSS, Total Soluble Solids) (ºBrix)), pero no de compuestos fenólicos y aromáticos (compuestos que se sintetizan más tarde en la baya). En los últimos años se han desarrollado métodos rápidos y no destructivos que permiten relacionar datos espectrales con la concentración de componentes químicos específicos (TSS, compuestos fenólicos, compuestos aromáticos, compuestos nitrogenados…). Dos de estas tecnologías son la espectroscopía de infra, Para ello, en primer lugar, se optimizaron tres técnicas para la extracción de compuestos volátiles en mosto: extracción mediante barrita agitadora absorbente (SBSE, Stir Bar Sorptive Extraction), su variante multi-SBSE (mSBSE), en la que se utilizaron barritas agitadoras de polidimetilsiloxano (PDMS) y de etilenglicol (EG) de forma simultánea, y microextracción en fase sólida mediante película fina (TF-SPME, Thin Film – Solid Phase Microextraction), en la que se probaron las películas finas de PDMS/carboxen (PDMS/CAR) y de PDMS/divinilbenceno (PDMS/DVB). Los factores optimizados fueron el modo, velocidad, tiempo y temperatura de extracción, y la adición de NaCl. A su vez, se puso a punto el análisis de dichos compuestos por cromatografía de gases-espectrometría de masas (GC-MS, Gas Chromatography – Mass Spectrometry). Una vez optimizadas las tres técnicas, se eligió la que mejores resultados proporcionó, que fue TF-SPME-GC-MS, con la película fina de PDMS/CAR y bajo las condiciones de inmersión directa (DI), a 500 rpm, durante 6 horas a 20 ⁰C. Dicha técnica se utilizó posteriormente como método de referencia para la determinación de compuestos volátiles en las muestras de mosto. En segundo lugar, se tomaron medidas espectrales, en condiciones de laboratorio, de 240 muestras de Vitis vinifera L. Tempranillo y 240 de Tempranillo Blanco, recogidas durante los años 2019 y 2020, mediante HSI en el rango 400-1.000 nm y mediante NIRS en el rango 1.100 – 2.100 nm. En tercer lugar, se midieron los TSS y se analizaron los compuestos volátiles de esas mismas muestras con el método TF-SPME-GC-MS optimizado, se integraron los cromatogramas y se obtuvieron, de esta forma, los datos de referencia. Por último, se construyeron los modelos de calibración multivariante, mediante regresión por mínimos cuadrados parciales modificados (MPLS), utilizando los datos espectrales adquiridos y los datos de referencia. Los resultados obtenidos demostraron que las técnicas HSI y NIRS permiten d

Phenolic compounds are very important for grapes and wines quality since these compounds can take part in color, mouthfeel and wine ageing potential, and they are also related to the human healthy properties of moderate wine consumption. The content of phenolic compounds in grapes depends on different factors, such as variety, climatic and geographical factors, cultural practices, and the stage of grape ripeness. Foliar application of biostimulants has been studied in the last years in order to mitigate the effect of climatic change in grapes and to enhance their composition and quality. In this work, it was studied the effect of foliar application of methyl jasmonate plus urea (MeJ + Ur), in Tempranillo vineyard, on the content of phenolic compounds in grapes and wines, during two consecutive vintages. These compounds (anthocyanins, flavanols, flavonols, phenolic acids, and stilbenes) were analysed, in both grapes and wines, by high performance liquid chromatography (HPLC). The effect of foliar treatment was season dependent, probably due to the differences in pre-harvest rainfall recorded. In the first season, the MeJ + Ur treatment favored the biosynthesis of anthocyanins, increasing their content in grapes; however, this effect was not observed in the wines. In the second vintage, the MeJ + Ur foliar application did not enhance the anthocyanin content in grapes or in wines. With respect to the other phenolic compounds, the foliar treatment did not improve their content in grapes, except for total flavonols in the second vintage. Foliar application of MeJ + Ur seems to be a good tool in order to enhance the anthocyanin content in grapes, which it is very interesting due to anthocyanins are the main phenolic compounds in red varieties, and they are responsible for the wine red color. Nevertheless, further studies should be carried out to achieve a better knowledge of the plant response to this treatment according to the climatic conditions. Moreover, it is necessa

Grape volatile compounds determine the wine quality and typicity. The aim of this work was to study the effects of several foliar applications in 'Garnacha', 'Tempranillo', and 'Graciano' grapevines in order to enhance their grape volatile composition. The field trial involved the application of two nitrogen compounds, urea (Ur) and phenylalanine (Phe), and two elicitors, methyl jasmonate (MeJ) and a yeast extract (YE). The analysis of grape volatile compounds was carried out by HS-SPME-GC-MS. For 'Garnacha', most terpenes, and C13 norisoprenoids increased their grape content by applying Ur and Phe, and especially MeJ. For 'Tempranillo', treatments with Ur and MeJ improved the synthesis of most terpenoids. For 'Graciano', a trend to decrease the terpenoids content in grapes with the treatments was observed; however, Phe application increased C13 norisoprenoids content. In conclusion, foliar application of, Phe or Ur, and an elicitor, MeJ, can be a useful tool to improve grape quality.

It is well known that grape aromatic composition is directly correlated to the final wine quality. To determine this composition, a previous stage of selective extraction is necessary, since the aromatic compounds are found in very low concentrations in the grapes. Therefore, in this work, the thin film microextraction technique (TF-SPME) was optimized, for first time, with the aim to analyze the volatile composition of the grape musts. The results obtained with the two commercially available absorbent materials for TF-SPME, polydimethylsiloxane/carboxene (PDMS/CAR) and PDMS/divinylbenzene (PDMS/DVB), were optimized and compared. To carry out the optimization, a randomized factorial design was performed combining the following factors and levels: extraction mode (headspace (HS), or direct immersion (DI)), stirring speed (500 and 1000 rpm), extraction time (1, 3 and 6 h), and extraction temperature (20, 40 and 60 °C). After performing a principal component analysis (PCA) and an analysis of variance (ANOVA) multifactorial, it was concluded that the best conditions for TF-SPME with PDMS/CAR were: direct immersion (DI), 500 rpm, 6 h, and 20 °C, while for TF-SPME with PDMS/DVB no conditions were found that maximized the extraction of most compounds, therefore compromise conditions were chosen: headspace (HS), 500 rpm, 6 h, and 40 °C. Finally, the comparison between the results obtained with both absorbents indicated that the absorbent that extracted better the volatile compounds from the musts with the TF-SPME technique, was PDMS/CAR, under the conditions: direct immersion (DI), 500 rpm, 6 h, and 20 °C.

The phenolic, aromatic and nitrogen composition of a wine determines its organoleptic profile and quality. Elicitors have been used as a tool to stimulate the plant’s defense systems, favoring the synthesis of secondary metabolites. In this pioneering study, the elicitor methyl jasmonate in conventional form (MeJ) and in nanoparticle form (ACP-MeJ), with a concentration ten times lower, was applied in a Tempranillo vineyard over two seasons. The phenolic, nitrogen and volatile composition and the sensory properties of the MeJ-based wines were determined. The results showed that the effects of foliar applications of MeJ modify the wine composition. Thus, although the total concentration of most of the groups of phenolic compounds was not altered, several compounds, such as petunidin-3-glucoside, quercetin-3-glucoside, epigallocatechin and most of the stilbenes, increased, in both years, in the treated wines. Amino acids were influenced differently in each of the years studied, and volatile compounds generally did not improve in the treated wines. However, the ACP-MeJ wines were the best rated by the tasters, highlighting their equilibrium on the taste and their genuineness and odor quality. Therefore, foliar applications of ACP-MeJ can be considered a useful tool to improve wine quality.

Foliar application has been studied to enhance grape composition and, therefore, wine quality. This work examined, for first time, the effects of foliar applications of methyl jasmonate (MeJ) and methyl jasmonate plus urea (MeJ+Ur) to Tempranillo vineyard on wine phenolic, aromatic and nitrogen composition over two vintages (2019 and 2020). A reduction in alcoholic degree was observed in MeJ and MeJ+Ur wines. The effect of foliar treatments was season-dependent. MeJ and MeJ+Ur wines were characterized, in the first vintage, by a higher content of total acylated anthocyanins, but a low content of total esters, alcohols and acids when compared with control wines. MeJ+Ur wines presented a higher total amino acids content than control and MeJ wines. However, in the second vintage, MeJ and MeJ+Ur wines presented an increase in some non-acylated anthocyanins, but only MeJ+Ur treatment increased the total content of flavonols, flavanols, hydroxycinnamic acids, stilbenes and total amino acids when compared with control wines. MeJ wines presented a low content of esters and acids, whereas MeJ+Ur did not show differences with control wines. Overall, the effect of MeJ+Ur foliar treatment was greater than the effect of MeJ application in order to improve the wine chemical composition.