How to transform the odor of a white wine into a red wine? Color it red!

Secondary (or specialised) metabolites such as terpenes and phenolic compounds are produced by plants for various roles which include defence against pathogens and herbivores, protection against abiotic stress, and plant signalling. Additionally, these metabolites influence grapevine quality traits such as colour, aroma, taste, and nutritional value. However, the biosynthesis of these metabolites is often complex and controlled by multiple genes which in grapevine are predominantly uncharacterised.

The aromatic quality of wines after a long aging period in bottle is one of key points for oenologists. The objective of this work is to determine the main representative aromatic compounds found in long aged wines from D.O.Ca. Rioja. This study was made by 32 wines from 1971 to 2010 vintages. Sotolon, acetaldehyde, phenylacetaldehyde, 1,1,6-trimethyl-1,2-dihydronaptalene (TDN), β-damascenone, Y-decalactone and Y-dodecalactone were determined as the most important oxidation markers by GC-MS analysis. Moreover, sensory analysis using triangular tests were performed from wines with and without the addition of the mentioned compounds. Four different concentrations of each odorant were added, as individual compounds and as mixtures. The additions were ranged from values close to the reference odour thresholds up to high level concentrations. The most identified aroma was sotolon, which is commonly associated to curry and coffee liqueur aromatic notes. Other oxidative compounds were easily detected by panellists, such as Y-decalactone (peach compote), Y-dodecalactone (ripe fruit). The mixtures of the odorants were most easily detected than the individual compounds. It should be noted that acetaldehyde and phenylacetaldehyde were rarely perceived and distinguished.

Bacillus velezensis and Trichoderma harzianum are relevant microorganisms used in viticulture as biocontrol agents against pathogens of trunk (e.g. Phaeoacremonium minimum), leaves (e.g. Plasmopara viticola) or fruit (e.g. Botrytis cinerea), or as biostimulants, improving the resilience of plants against biotic or abiotic stressors through different direct and non-direct interactions.
In this biotechnological approach, formulation plays a crucial role. Controlling water activity in the product, thus stabilising microbial viability is key to ensuring effective application. We present the benefits of the citrate ester CITROFOL® AI (triethyl citrate) as a novel bio-based carrier liquid in microbial formulations. CITROFOL® AI is safe for humans and the environment, thus offering a promising base for sustainable treatments in viticulture.

Fungal bunch rots of grapes cause major losses to grape yield worldwide, yet the impact these moulds have on grape and wine quality is not well characterised. We sought to investigate the formation of unwanted volatile compounds of fungal origin in both synthetic grape juice culture media and in inoculated grape berries. Botrytis cinerea, Aspergillus niger, Aspergillus carbonarius, or Pencillium expansum were grown in synthetic grape juice medium and the culture homogenates analysed 4 and 7 days post inoculation. HS-SPME-GC-MS analysis of the culture homogenates 4 days post inoculation demonstrated that each of the fungi examined produced varying quantities of the mushroom or fungus-like aroma compounds, 1-Octen-3-ol, 1-Octen-3-one and 3-Octanone with A. carbonarius producing up to ten times the amounts of all three metabolites per mg of dry mycelium.

Wine contains so many odorants that all its olfaction-related perceptions are, inevitably, the result of the interaction between many odorants.