Evaluation of three alternative strategies for the long-term remediation of reductive off-odours in wines

G.r.a.s.p.o. Is not only the acronym for gruppo di ricerca per la salvaguardia e preservazione dell’originalità viticola di ogni territorio (‘research group for the safeguard and preservation of the originality of every territory’s grapes’), and is not just the italian synonym for ‘raspo’ (‘peduncle’) as treccani dictionary mentions: in the veneto dialect it is the whole bunch of grapes.

Global warming is shifting vine phenology, resulting in a decoupling of phenolic and technological berry ripening. This is altering the balance of fruit traits, which is key relevance to winegrowers

Erisiphe necator is endemic in the Rioja Appellation of Origin. Vine growers exert significant effort to protect their crops, given the economic losses this disease causes. Different studies have shown that using Gubler-Thomas Model (GTM) can reduce treatments by up to 20% compared to a full-time protection strategy. This reduction is achieved by optimizing applications based on temperature variations in late spring and summer when the disease’s conidial stage is active.

The main innovation in the VINIoT service is the joint use of two technologies that are currently used separately: vineyard monitoring using multispectral imaging and deployed terrain sensors. One part of the system is based on the development of artificial intelligence algorithms that are feed on the images of the multispectral camera and IoT sensors, high-level information on water stress, grape ripening status and the presence of diseases. In order to obtain algorithms to determine the state of ripening of the grapes and avoid losing information due to the diversity of the grape berries, it was decided to work along the first year 2020 at berry scale in the laboratory, during the second year at the cluster scale and on the last year at plot scale. Different varieties of white and red grapes were used; in the case of Galicia we worked with the white grape variety Treixadura and the red variety Mencía. During the 2020 and 2021 campaigns, multispectral images were taken in the visible and infrared range of: 1) sets of 100 grapes classifying them by means of densimetric baths, 2) individual bunches. The images taken with the laboratory analysis of the ripening stage were correlated. Technological maturity, pH, probable degree, malic acid content, tartaric acid content and parameters for assessing phenolic maturity, IPT, anthocyanin content were determined. It has been calculated for each single image the mean value of each spectral band (only taking into account the pixels of interest) and a correlation study of these values with laboratory data has been carried out. These studies are still provisional and it will be necessary to continue with them, jointly with the training of the machine learning algorithms. Processed data will allow to determine the sensitivity of the multispectral images and select bands of interest in maturation.

Specific inactivated yeast derivatives (SYDS) are obtained from s. cerevisiae yeasts by various processes (thermal, mechanical, and enzymatic) and have diverse oenological applications to improve wine quality. However, different impacts on wine sensory and aromas were reported, depending on syds types and fractions, wine matrices, and experimental settings. Few works have examined the impact of SYDS on aromas considering also those on wine macromolecules influencing organoleptic properties.