Harvest-Time Thermal Conditions and Bioprotection as Climate-Adaptive Strategies for Aroma Preservation in Harslevelu Wines from the Tokaj Region

Abstract

Harvest-time conditions can vary considerably within a single day, yet their influence on wine aroma development is still not fully understood. In this study, the effect of thermal conditions at harvest—comparing night and midday picking—was examined in relation to the volatile composition and sensory expression of Hárslevel? wines from the Tokaj region. The work is considered within the broader context of low-input and climate-adaptive winemaking, although no direct environmental measurements were performed. Grapes were harvested on the same day, either during the night under cool pre-dawn conditions (18 °C) or at midday under higher ambient temperatures (28 °C), and processed using controlled microvinification protocols. Bioprotection with Metschnikowia pulcherrima was applied either alone or in combination with SO?. Volatile compounds were analysed by HS-SPME–GC–MS on a semi-quantitative basis, and the resulting dataset was evaluated using exploratory multivariate approaches. Sensory assessment followed OIV guidelines and was interpreted primarily as descriptive qualitative evaluation. Across treatments, wines produced from night-harvested grapes were more often associated with volatile compounds linked to fresh, floral and citrus-related sensory attributes. By contrast, wines obtained from midday-harvested grapes tended to show riper aromatic profiles together with higher perceived acidity. The use of bioprotection was associated with a greater diversity of fermentation-derived aroma compounds; however, it did not eliminate the differentiation related to harvest-time conditions. A similar pattern was observed in the sensory data, where wines from night-harvested grapes were generally described as having higher aromatic purity, freshness and overall harmony. Taken together, these observations point to a potential role of harvest-time conditions—including temperature and associated environmental factors—in shaping aromatic expression in dry white wines. Under the conditions of this study, cooler harvest conditions—especially when combined with bioprotection—appear to support aroma preservation and stylistic balance. At the same time, the study did not include direct measurements of environmental performance. For this reason, any interpretation of these practices as climate-adaptive should be understood in a conceptual and process-oriented sense, rather than as quantitatively demonstrated sustainability outcomes.