Assessing macro-elements contents in vine leaves and grape berries of Vitis vinifera using near-infrared spectroscopy coupled with chemometrics

Of biocontrol products and resistant grape varieties, synthetic pesticides are still widely used to control fungal diseases and protect vines from potential damage caused by pests. The use of pesticides is strictly regulated, and their use can sometimes lead to transfer from the grapes to the must and then into the wine. The study of pesticide residues in grapes and wines is commonly carried out by wine producers in order, among other things, to optimize treatment routes, check that products comply with regulations, and ultimately guarantee the food safety of the wine.

The quality of any alcoholic beverage depends on many parameters, such as cultivars, harvesting time, fermentation, distillation technology used, quality and type of wooden barrels (in case of matured drinks), etc.; however, the most important factor in their classification is content of volatile compounds.

Elemental composition, measured as the concentrations of different elements present in a given tissue at a given time point, is a key indicator of vine health and development. While elemental composition and other high-throughput phenotyping approaches yield tremendous insight into the growth, physiology, and health of vines, costs and labor associated with repeated measures over time can be cost-prohibitive. Recent advances in handheld sensors that measure hyperspectral reflectance patterns of leaf tissue may serve as an affordable proxy for other types of phenotypic data, including elemental composition. Here, we ask if reflectance patterns of dried Chambourcin leaf tissue from an experimental grafting vineyard can predict the known elemental composition of those leaves.

Deficit irrigation strategies can be valuable means to improve grape quality while saving important amounts of water. A simple way to use deficit irrigation can be based on irrigating a vineyard with a determined level of crop evapotranspiration. Using a precise physiological parameter indicating water status, irrigation could be managed to maintain a specific pre-dawn leaf water potential.

Over the last years, the potential use of non-Saccharomyces yeasts to modulate the production of target metabolites of oenological interest has been well recognized. Among non-Saccharomyces yeasts, Starmerella bacillaris (synonym Candida zemplinina) is considered one of the most promising species to satisfy modern market and consumers preferences due to its peculiar characteristic (enhance glycerol and total acidity contents and reduce ethanol production). Mixed fermentations using Starm. bacillaris and Saccharomyces cerevisiae starter cultures represent a way to modulate metabolites of enological interest, taking advantage of the phenotypic specificities of the former and the ability of the latter to complete the alcoholic fermentation. However, the consumption of nutrients by these species and their produced metabolites may inhibit or stimulate the growth (and malolactic activity) of lactic acid bacteria (LAB).