Harvest timing is a critical factor in viticulture, as it directly influences grape composition and, consequently, wine quality. This study evaluated the effects of harvest timing on the physical and chemical traits of two widely cultivated grape varieties from the Trebinje vineyard area, Bosnia and Herzegovina. Basic chemical parameters (total soluble solids, pH, titratable acidity) were measured alongside cluster and berry traits, including length, width, and weight of clusters; the number and weight of berries; the skin and flesh weight of 100 berries; and the number and weigh of seeds. Early-harvested grapes showed greater cluster weight but lower total soluble solids, higher titratable acidity, and lower pH compared to later harvests in both cultivars. Changes in cluster and berry traits were more pronounced in ‘Vranac’, where berry weight, skin and flesh mass increased significantly at later harvests, however, in ‘Žilavka’ only the seed weight was notably affected. Across all harvests period, ‘Žilavka’ consistently exhibited higher total soluble solids and lower pH values than ‘Vranac’, indicating a strong varietal effect on grape quality. These findings highlight that delaying harvest within the recommended window can enhance grape composition, while varietal differences determine the extent of morphological and chemical changes during ripening.

Fermentation is a crucial process in the production of alcoholic beverages such as spirits, which produces a number of volatile compounds due to the metabolic activities of yeast. These volatile compounds, together with the volatile components of the raw materials and the volatile compounds produced during the distillation and aging process, play a crucial role in determining the final flavor and aroma of spirits. In this manuscript, we provide a comprehensive overview of yeast fermentation and the volatile compounds produced during alcoholic fermentation. We will establish a link between the microbiome and volatile compounds during alcoholic fermentation and describe the various factors that influence volatile compound production, including yeast strain, temperature, pH, and nutrient availability. We will also discuss the effects of these volatile compounds on the sensory properties of spirits and describe the major aroma compounds in these alcoholic beverages.