Preservation of white wine pomace by high hydrostatic pressure.

The effect of different high hydrostatic pressure (HHP) treatments (400, 600 MPa for 1, 6 min) on white wine pomace was studied throughout storage conditions (270 days) at different temperature conditions (4° and 20 °C). The final use of this product would be as an ingredient for food products preservation. Microbiological, enzyme and physico-chemical parameters were evaluated after processing and during storage. HHP greatly reduced the microbial counts of treated pomace and allowed obtaining a safe product with a long shelf-life at 4 and 20 °C. The HHP treatment also preserved phenolic compounds content, however an important reduction of these compounds was found during storage since the polyphenol oxidase enzyme remained active after the treatment and during storage. Phenolic compounds were better preserved during storage at 4 °C than at 20 °C. The application of HHP at 600 MPa/6 min and the refrigeration of the treated pomace would allow obtaining a microbiologically safe pomace with high levels of phenolic compounds with a shelf-life of 90 days. The activity of the enzyme should be limited in future to ensure a long shelf-life of the processed pomace.

Variation in Susceptibility to Downy Mildew Infection in Spanish Minority Vine Varieties.

Downy mildew is one of the most destructive diseases affecting grapevines (Vitis vinifera L.). Caused by the oomycete Plasmopara viticola (Berk. and Curt.) Berl. and de Toni, it can appear anywhere where vines are cultivated. It is habitually controlled by the application of phytosanitary agents (copper-based or systemic) at different stages of the vine growth cycle. This, however, is costly, can lead to reduced yields, has a considerable environmental impact, and its overuse close to harvest can cause fermentation problems. All grapevines are susceptible to this disease, although the degree of susceptibility differs between varieties. Market demands and European legislation on viticulture and the use of phytosanitary agents (art. 14 of Directive 128/2009/EC) now make it important to know the sensitivity of all available varieties, including minority varieties. Such knowledge allows for a more appropriate use of phytosanitary agents, fosters the commercial use of these varieties and thus increases the offer of wines associated with different terroirs, and helps identify material for use in crop improvement programmes via crossing or genetic transformation, etc. Over 2020-2021, the susceptibility to P. viticola of 63 minority vine varieties from different regions of Spain was examined in the laboratory using the leaf disc technique. Some 87% of these varieties were highly susceptible and 11% moderately susceptible; just 2% showed low susceptibility. The least susceptible of all was the variety Morate (Madrid, IMIDRA). Those showing intermediate susceptibility included the varieties Sanguina (Castilla la Mancha, IVICAM), Planta Mula (Comunidad Valenciana, ITVE), Rayada Melonera (Madrid, IMIDRA), Zamarrica (Galicia, EVEGA), Cariñena Roja (Cataluña, INCAVI), Mandrègue (Aragón, DGA) and Bastardo Blanco (Extremadura, CICYTEX). The highly susceptible varieties could be differentiated into three subgroups depending on sporulation severity and density.

Crop forcing technique and irrigation strategy modified the content and phenolic profile of cv. Tempranillo grape berries grown in a semi-arid climate.

BACKGROUND: Climate change modifies the content and phenolic profiles of grapes and wines. It is known that high temperatures, related to climate change, reduce anthocyanins and procyanidin (catechin and tannin) compounds accumulated in the berries. In recent years, with the aim of improving the phenolic composition of the berries, the technique of crop forcing has been proposed to delay grape ripening to a more favourable period of temperatures. RESULTS: In this study, crop forcing was applied to cv. Tempranillo vines on two different dates, after flowering (F1) and after fruit set (F2), and compared to a treatment control (NF, without forcing). Additionally, as a secondary factor, two irrigation strategies were established in each treatment: irrigation with no water stress, and a pre-veraison deficit irrigation. The study was carried out in three consecutive years (2017-2019). For most of the parameters analysed, no interaction was found. Therefore, for these parameters, the effect of each of these techniques was investigated independently. Regardless of the irrigation strategy, F2 berries achieved higher contents of catechins and anthocyanins than NF berries. Each year, regardless of the irrigation strategy, crop forcing increased the content of monoglucoside forms, and had a positive effect on the total content of malvidin, petunidin, delphinidin, peonidin and malvidin derivatives, but only affected acetyl and coumaryl forms in 2017. However, the effect of irrigation strategy was less significant and consistent, being more dependent on the vintage. CONCLUSION: Regardless of vine water status, crop forcing technique applied after fruit set could be used by vine growers to delay ripening of the grapes and thus achieve an increase in the anthocyanin characteristics of the grapes. © 2023 Society of Chemical Industry.

Improving the Phenolic Content of Tempranillo Grapes by Sustainable Strategies in the Vineyard.

Wine phenolics are of considerable interest due to their implication in the organoleptic appreciation of wines and due to their bioactive functions as antioxidants. In this work, the effects of sustainable strategies in the vineyard, regulated deficit irrigation treatments (RDI) and crop load level (CL) on Tempranillo grape phenolics over two seasons was studied. Rainfed (T), early (EDI) and late (LDI) regulated deficit irrigation was applied. Cluster thinning (TH) and control (C) without cluster removal were also applied under each irrigation treatment. The effect of CL remained independent of RDI for all compounds, except for phenolic acids. The RDI influence on the grape skin phenolic profile was higher than CL in the dry season (2009); however, in 2010, the effect of CL was greater. In 2009, a tendency to increase anthocyanin and hydroxycinnamic acid content in grape skins was registered in EDI with respect to T. However, significant decreases in hydroxycinnamic and flavanol compounds were found in LDI. In 2010, the wettest year, CL increased all phenolic families' content. Thus, it can be concluded that the effects of RDI and cluster thinning treatments depend on the family of compounds considered and the meteorological conditions of the year.

Effect of the timing of water deficit on the must amino acid profile of Tempranillo grapes grown under the semiarid conditions of SW Spain.

Must nitrogen is very important for successful fermentation. Irrigation can influence vine nitrogen availability, and therefore must nitrogen content and wine quality. The aim of this work was to assess the effect of vine water status on the nitrogen concentration of cv. Tempranillo grown under semiarid conditions. A rainfed and two regulated deficit irrigation (RDI) strategies, late (LDI) and early deficit irrigation (EDI) were applied during pre- and post-veraison respectively periods over two seasons in Badajoz (Spain). Twenty-eight amino acids, amines and ammonia were determined by high performance liquid chromatography (HPLC) in the must. Results showed an effect of the pre-veraison vine water status on the must amino acid concentration. Higher values of nitrogenous indices were reached in musts from LDI treatments, mainly in the dry year. Significant correlations between pre-veraison stem water potential and 19 amino acid concentrations were observed. Therefore, LDI was a more suitable strategy for increasing the content of nitrogenous substances in the must.