Unraveling genetic, compositional, and organoleptic traits of elephant garlic of different geographical origins.

The ancient native variety of elephant garlic, known as "Aglione della Valdichiana" and cultivated in the Valdichiana area of Tuscany, Italy, has gained recent recognition in the National Catalog of Local Varieties. The renewed interest in traditional products has led to a focus on identifying local varieties of elephant garlic, driven by their distinctive organoleptic and nutritional characteristics. However, other types of elephant garlic nowadays available on the market appear similar, but challenges exist in discerning their origin and composition. This study focused on characterizing elephant garlic from Lazio, Italy, and the Val di Chiana region through genetic, chemical, and aromatic analyses to understand genetic and geographic influences. ISSR markers differentiated elephant garlic from common varieties and highlighted regional genetic diversity. Chemical analysis revealed higher polyphenol content and antioxidant activity in elephant garlic compared to common garlic. Moreover, analysis highlights the variability in the concentrations of sulfur-containing compounds between common and elephant garlic. Aromatic and sensory assessments underscored distinctions between garlic types and regions, emphasizing the significant impact of geographic origin and genetic background on metabolite profiles in Allium genotypes.

Feasibility assessment of a low-cost visible spectroscopy-based prototype for monitoring polyphenol extraction in fermenting musts.

BACKGROUND: Polyphenols have long been used to evaluate grape and wine quality and it is necessary to measure them throughout various winemaking stages. They are currently assessed predominantly through analytical methods, which are characterized by time-consuming procedures and environmentally harmful practices. Non-destructive spectroscopy-based devices offer an alternative but they tend to be costly and not readily accessible for smaller wineries. This study introduces the initial steps in employing a portable, user-friendly, and cost-effective visible (VIS) spectrophotometer prototype for direct polyphenol measurement during winemaking. RESULTS: Grapes (cv Syrah, Bobal, and Cabernet Sauvignon) at different maturation stages were fermented with or without stems. Throughout fermentation, parameters such as color intensity, total polyphenol index, total anthocyanins, and tannins were monitored. Concurrently, VIS spectra were acquired using both the prototype and a commercial instrument. Chemometric approaches were then applied to establish correlation models between spectra and destructive analyses. The prototype models demonstrated an acceptable level of confidence for only a few parameters, indicating their lack of complete reliability at this stage. CONCLUSIONS: Visible spectroscopy is already utilized for polyphenol analysis in winemaking but the aspiration to automate the process in wineries, particularly with low-cost devices, remains unrealized. This study investigates the feasibility of a low-cost and user-friendly spectrophotometer. The results indicate that, in the early stages of prototype utilization, the goal is attainable but requires further development and in-depth assessments. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Optimizing the winemaking process: NIR spectroscopy and e-nose analysis for the online monitoring of fermentation.

BACKGROUND: In the winemaking process, the rapid determination of specific quality parameters such as sugar content, pH, acidity, concentrations of phenolic compounds, anthocyanins and volatile organic compounds is crucial for high-quality wine production. Traditional analytical methods allow for precise quantification of these parameters but are time-consuming and expensive. This article explores the potential application of non-destructive analytical technique (NDAT) (near infra-red [NIR] and e-nose), as efficient alternatives for online monitoring of fermentation working on two different winemaking tanks and applying chemometrics to develop predictive models to correlate non-destructive and analytical data. RESULTS: NIR measurements have been used to build principal components regression models, showing good prediction capability for polyphenols, anthocyanins, glucose and fructose. Both offline and online e-nose applications demonstrate good capability of discriminating different fermentation phases, in agreement with aromatic profile changes observed via gas chromatography-mass spectrometry analysis. Moreover, correlation analysis reveals the potential of quartz microbalances, Taguchi Gas Sensors and H2 S sensors in predicting the concentration of compounds of great interest for winemaking (e.g. C6 alcohols, ketones, terpenes and ethyl esters) highlighting the robust connection between sensor data and specific chemical classes. CONCLUSION: This research aims to showcase the potential employment of NDAT for online monitoring the evolution of must composition during fermentation. The proposed methods could potentially fulfil a longstanding requirement of winemakers, enabling them to closely monitor fermentation allowing the timely making of important technical decisions aimed at achieving oenological objectives in wine production. © 2024 Society of Chemical Industry.

Postharvest wine grape dehydration: ethanol dissipation from grape and biochemical changes.

BACKGROUND: During postharvest dehydration, grapes are subject to metabolic changes including ethanol anabolism and catabolism. These changes affect the quality of the final product and ethanol production is a key step. Ethanol dissipation has never been measured during postharvest wine grape dehydration. Thus, the present study aimed to: (i) monitor ethanol dissipation and (ii) investigate chemical-biochemical changes in berries during dehydration. RESULTS: Ethanol dissipation from Raboso grapes, under controlled postharvest dehydration, was found to comprise up to 36% of weight loss (w.l.). Moreover, the activity of enzymes involved in the anaerobic metabolism of grapes was investigated. Ethanol dissipation was highly correlated with grape weight loss (r2 = 0.989). Alcohol dehydrogenase activity, responsible for the reduction of ethanol to acetaldehyde, declined significantly with w.l. Similarly, pyruvate decarboxylase and lactate dehydrogenase reduced their activity. High lipoxygenase activity was measured at 27% w.l., whereas polyphenol oxidation was constant and declined in the last sampling. CONCLUSION: Ethanol dissipation during postharvest dehydration allows for reducing anaerobic metabolism and promotes oxidative metabolism. The sensor used can be a useful commercial tool for monitoring berry metabolism. © 2023 Society of Chemical Industry.

Nitrogen maceration of wine grape: An alternative and sustainable technique to carbonic maceration.

Carbonic maceration (CM) consists in placing intact grape bunches into a sealed tank to have a natural or artificially created carbon dioxide atmosphere. No articles have been published on the comparison between CM and nitrogen maceration (NM). Therefore, the present study aimed at testing the use of alternative maceration technique (NM) in alternative to CM, to create the conditions of anoxia on the Gamay variety. The results showed a higher concentration of polyphenols and anthocyanins in the macerated wines, especially in NM wine. Concerning VOCs (Volatile Organic Compounds), the CM wine showed the highest content in esters while the total alcohol content was slightly higher in the NM wines. The CM wine had the highest content in volatile medium chain fatty acids (MCFA). E-nose measurements revealed a clear separation among the samples, and the E-nose data, in PCA computation, were generally overlapped by the PCA of VOCs analysis. The NM showed a potential as environmentally sustainable technique useful to produce a new style of macerated and aromatic wines.

Pre-processing Cooling of Harvested Grapes Induces Changes in Berry Composition and Metabolism, and Affects Quality and Aroma Traits of the Resulting Wine.

Due to the greenhouse gas increase, grapes are often exposed to high temperatures in several growing areas especially during the final developmental stages, and this is particularly true when early ripening cultivars are harvested. This may cause undesirable effects on berry metabolism and composition and wine quality, particularly concerning the aroma profile. Harvesting at night or keeping the harvested grapes in cold rooms before vinification are empirical protocols applied in specific viticultural areas. To study the effects of decreasing berry temperature after harvest, white-skinned berries (cv Vermentino) were maintained at 4 or 10°C for 24 or 48 h before processing (pre-cooling). Control grapes were kept at 22°C. Grapes cooled at 10°C for 24 and 48 h resulted richer in polyphenols and showed a significant up-regulation of genes involved in polyphenols biosynthesis (i.e., VvPAL, VvSTS2, and VvFLS1). Similar behavior was observed in samples kept at 4°C for 48 h. Pre-cooling induced specific changes in the volatile organic compound (VOC) profiles. In particular, higher amounts of a specific subcategory of terpenes, namely sesquiterpenes, were detected in cooled samples. The induction of the expression of key genes involved in terpenoids biosynthesis (VvHDR, VvDX3, VvTER, VvGT14) was detected in cooled grapes, with variable effects depending on temperature and treatment duration. In both cooled samples, the evolution of alcoholic fermentation followed a regular trend but ended earlier. Higher phenolic content was detected in wines obtained from the 10°C-treated grapes. Higher residual concentration of malic acid at the end of fermentation was detected in wine samples from grapes pre-cooled at 4°C. Sesquiterpenes also showed a general increase in wines from cooled grapes, especially after pre-cooling at 10°C for 48 h. Different sensory profiles characterized the wine samples, with the best scores in terms of general pleasantness obtained by the wine produced from grapes pre-cooled at 4°C for 24 h. These results demonstrate that pre-cooling harvested grapes induces specific effect on the VOC profile and other quality parameters of Vermentino wine, and this appears to be the result of specific metabolic and compositional changes occurring in the berries.

Ozone and Bioactive Compounds in Grapes and Wine.

Ozone is widely used in the agri-food and food processing industries mainly as a sanitizing agent. However, it has recently become clear that ozone exposition leads to another important benefit: in living tissues, the induced-oxidative stress triggers the antioxidant response, and, therefore, it enhances the production of antioxidant and stress-related secondary metabolites. As such, ozone can be considered an abiotic elicitor. The goal of the present review was to critically summarize knowledge about the possibility of improving bioactive compounds and, consequently, the health-related properties of grapes and wine, by using ozone. The greatest interest has been given not only to the pre- and post-harvest treatment of table and wine grapes, but also to the explanation of the mechanisms involved in the ozone-related response and the main secondary metabolites biosynthetic pathways. From the literature available, it is clear that the effect of ozone treatment on health-related properties and secondary metabolites accumulation depends on many factors, such as the cultivar, but also the form (water or gaseous), doses, and application method of ozone. Most of the published papers report an increase in antioxidant compounds (e.g., polyphenols) and stress-related volatiles, confirming the hypothesis that ozone could be used to improve berry and wine compositional and sensory quality.

Postharvest Water Loss of Wine Grape: When, What and Why.

In postharvest science, water loss is always considered a negative factor threatening fruit and vegetable quality, but in the wine field, this physical process is employed to provide high-quality wine, such as Amarone and Passito wines. The main reason for this is the significant metabolic changes occurring during wine grape water loss, changes that are highly dependent on the specific water loss rate and level, as well as the ambient conditions under which grapes are kept to achieve dehydration. In this review, hints on the main techniques used to induce postharvest wine grape water loss and information on the most important metabolic changes occurring in grape berries during water loss are reported. The quality of wines produced from dried/dehydrated/withered grapes is also discussed, together with an update on the application of innovative non-destructive techniques in the wine sector. A wide survey of the scientific papers published all over the world on the topic has been carried out.

Methyl jasmonate and ozone affect the antioxidant system and the quality of wine grape during postharvest partial dehydration.

Postharvest partial dehydration is a technique used in the production of important dry and sweet wines in Italy. An accurate management of the dehydration environmental parameters allows for the modulation of berry metabolism and the maintenance/improvement of the enochemical quality of grapes. As it is known that water loss induces oxidative processes in berries, our hypothesis was that methyl jasmonate (MeJA) and ozone (O3), as postharvest treatments before partial dehydration, might be beneficial for grape berry quality. Grape bunches were postharvest treated with 10 or 100 µM MeJA at 20 °C or with ozone gas at 10 °C, in 70% relative humidity (RH) and air flow, for 12 h; the control bunches were untreated and kept at 20 °C for 12 h. Subsequently, partial dehydration was performed at 10 °C until a 30% weight loss (w.l.) was reached. MeJA hastened grape berry water loss. Polyphenol and flavonoid contents at the end of the partial dehydration were lower in the MeJA-treated berries than in the control and ozone samples. Superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX) activity rates increased in the treated samples. In contrast, lipoxygenase (LOX) and polyphenoloxidase (PPO) had lower activities in the MeJA-treated samples than in the controls. It would seem that MeJA accelerates grape water loss but at the same time activates the antioxidant system. Ozone does not accelerate grape water loss but induces the antioxidant system and increases polyphenol content.