Vinificación de mínima intervención: Evaluación del uso de quitosano y reducción de sulfitos añadidos en cultivares Marselan, Merlot y Tannat

Sulfur dioxide is one of the most widely used additives in the food industry due to its antimicrobial and antioxidant properties. In winemaking, it is the most widely used additive due to its ability to inhibit the growth of undesirable microorganisms and prevent oxidative changes. However, it has been classified as slightly toxic, negatively affecting the health of 1% of consumers and causing reactions such as bronchospasm, bradycardia, urticaria, angioedema, hypotension, diarrhea, dermatitis, and anaphylactic reactions. Wine is one of the main sources of sulfite intake in adults, often exceeding acceptable daily levels. In this context, winemakers have responded to these concerns by adopting more sustainable and safer production strategies, minimizing negative impacts, with the aim of producing safe products that are in line with contemporary market demand, without compromising the quality of the final product. This study evaluated alternatives to reduce or replace the added sulfite content in wines from the Marselan, Merlot, and Tannat cultivars, produced with minimal intervention during the 2024 harvest. The fermentation kinetics, microbiological, physicochemical, phenolic, and colorimetric composition of the wines were analyzed. The minimal intervention treatments were vinified without the addition of yeasts, with Q being the addition of chitosan (100 mg/L), SO₂R corresponds to a reduction in added sulfites (30 mg/L), SO₂R+Q is a combination of the above treatments, and a control treatment (VT) with conventional addition of sulfur dioxide (125 mg/L) and inoculation of selected yeasts. Microbiological counts showed that, in Marselan and Merlot, the control wines had a lower yeast population than the minimal intervention treatments, with no significant differences in lactic acid bacteria. In Tannat, the control treatment showed lower counts of these bacteria, with no differences in the yeast population. Fermentation kinetics were slower in the minimal intervention musts compared to the control treatment. The chitosan treatment showed the highest color intensity in all three cultivars. In terms of phenolic composition, SO₂R and VT showed the highest concentrations in Marselan and Merlot, while in Tannat, the highest values were observed in Q and SO₂R+Q. Sensory analysis in Merlot showed no differences between treatments. In Tannat, the Q and SO₂R wines obtained the same preference as the control. At Marselan, sensory evaluation was not performed due to the general condition of the wine, highlighting the importance of the health and quality of the raw material. This work provides technical evidence on the impact of minimal intervention strategies on the microbiological stability and oenological composition of wine, and represents a contribution to the search for more sustainable practices in contemporary viticulture.