Effects of fertigation by elicitors enriched in amino acids from vegetal and animal origins on Syrah plant gas exchange and grape quality

Variety and year: Two key factors on amino acids and biogenic amines content in grapes

Amino acids have proved to play a key role in the development of volatile compounds present in wine with determining repercussions on the final wine bouquets. Biogenic amines originate from the chemical transformations of amino acids found in various foods, a phenomenon that has given rise to several health-related concerns among consumers. In the present research, the evaluation of two of the most influential factors: variety (genetic) and year (climatic conditions) on these compounds in grapes has been performed. Eight Vitis vinifera varieties have been collected during three years and the content of nineteen amino acids, two biogenic amines, and the ammonium ion has been quantified using the HPLC-PDA technique. The genetic factor has proved to be an influential variable (p-value < 0.05) with mean values of amino acids ranging from 896.89 to 1713.79 mg/L and of biogenic amines ranging from 10.61 to 22.28 mg/L. The climatic conditions have shown to be an influential factor as well (p-value < 0.05), being the low temperatures and rainfall and the high solar radiation favour the development of the amino acid and avoid biogenic amines accumulation in grapes.

Influence of different types of LEDs lights on the formation of volatile sulfur compounds in white and rosé wines

The effect of LEDs light on the formation of volatile sulfur compounds (VSCs) and the final sensory quality of white and rosé wines was evaluated. Thus, different commercial wines were exposed for ten days to three types of lights. All wine samples were analyzed throughout the exposure period to determine the usual oenological parameters together with some other chemical characteristics (color evolution; riboflavin, cysteine and methionine photodegradation), VSC amounts and sensory characteristics. The results showed that the wines exposed to ultraviolet light suffered greater degradation of the aromatic precursors, mainly riboflavin, and had higher concentrations of VSCs. Regarding LED lights, these produced minimal degradative effects. So that we can consider this type of light as an alternative to reduce the economic impact that currently occurs due to the photodegradation of bottled wines.

The Impact of Hanseniaspora vineae Fermentation and Ageing on Lees on the Terpenic Aromatic Profile of White Wines of the Albillo Variety

Hanseniaspora vineae is a non-Saccharomyces yeast that has a powerful impact on the sensory profile of wines. Its effect on the aromatic profile of non-aromatic grape varieties, such as Albillo Mayor (Vitis vinifera, L), during vinification is a useful biotechnology to improve sensory complexity. Fermentation in steel barrels using Hanseniaspora vineae and sequential inoculation with Saccharomyces cerevisiae have been used to study the formation of terpenes and cell lysis in the production of Albillo white wines. The GC-MS analysis profile shows a significant effect of H. vineae fermentation on the contents of terpenes (≈×3), mainly in linalool (>×3), β-citronellol (>×4), geraniol (>×2) and α-terpineol (≈×2). The contents of several polyoxygenated terpenes and some volatile phenols with a spicy aroma were increased during fermentation. In summary, Hanseniaspora vineae releases a large number of cell wall polysaccharides during fermentation that affect wine palatability and structure. Hanseniaspora vineae is a powerful bio-tool to enhance the fruitiness, floral notes and freshness in non-aromatic white varieties.

White wine processing by UHPH without SO2. Elimination of microbial populations and effect in oxidative enzymes, colloidal stability and sensory quality

The use of UHPH sterilization in the absence of SO₂ has been used to eliminate wild microorganisms and inactivate oxidative enzymes. A white must of the Muscat of Alexandria grape variety was continuously processed by UHPH at 300 MPa (inlet temperature: 23-25 °C). The initial microbial load of the settled must was 4-log CFU/mL for both yeast and moulds, and slightly lower for bacteria. After UHPH processing, no microorganisms were detected in 1 mL. UHPH musts remain without fermentative activity for more than 60 days. Concentrations of the thermal markers indicated the absence of thermal damage in the UHPH-treated musts, since 5-hydroxymethylfurfural was not detected. In addition, the must treated by UHPH keeps terpene concentrations similar to those of the untreated controls. A strong inactivation of the oxidative enzymes was observed, with no browning at room temperature for more than 3 days. The antioxidant value of the UHPH-treated must was 156% higher than the control.