Residual sugars (RS) in wine are the sugars that remain in a wine after fermentation is complete. In some wine styles, such as semi-dry wines, the accurate measurement of the RS concentration is critical for both qualitative and legislative reasons. Brix, measured by a simple refractometer, can give a good estimation of the RS concentration in the must, but during fermentation, the presence of alcohol leads to inaccurate sugar measurements. In order to measure the RS accurately, other more precise techniques are used, most of which are expensive or require professional skills. Therefore, novel approaches for rapid, easy, and practical measurements for estimating the sugar content were suggested over the years. However, most of these methods do not supply an actual measurement of RS but rather give brix values, and those that measure RS involve special equipment, which is less relevant for small wineries. This study suggests a novel model for predicting and controlling the wine's residual sugar. The data the model uses is the initial brix of the must before fermentation and its density during fermentation. The model was created by measuring actual residual sugars during the fermentation of natural and synthetic musts, with various degrees of initial brix levels, while simultaneously measuring their densities and correlating the two measurements. Linear regression between the residual sugar of the wine and its density was obtained for all treatments and repetitions (i.e., different values of must initial brix) with R² values above 0.97. Using the model, one can calculate (before commencing the fermentation) the density values at which the fermentation will reach a particular desired residual sugar value for a specific initial brix level; the model is applicable for the fermentation conditions used in this work, i.e., brix levels of 18-27˚Bx, Saccharomyces cerevisiae strains (fx-33 and fx-10) in common conditions of fermentation regarding temperature and aeration.

The wild grapevine, Vitis vinifera subsp. sylvestris grows naturally throughout the northern hemisphere, including the Mediterranean region. Wild grapevines were also observed sporadically across the southern Levant and have been considered a non-native feral plant. Nevertheless, no formal characterization was conducted for wild grapevines in this region; thus, its taxonomical assignment remains elusive. Previously we have shown that the wild grapevine populations growing in northern Israel are genetically separated from the feral domesticated forms. The aim of this work was to comprehensively describe the morphological, anatomical, and ecological traits of wild grapevines naturally thriving in two distinct habitats in Israel. The dioicous nature of the wild grapevine, as well as their flower and pollen morphology, their characteristic sylvestris fruit and seed morphology, in addition to the occurrence of natural germination of seeds in close vicinity to the mother plant, all lead to our conclusion that these plants belong to Vitis vinifera subsp. Sylvestris, and should be included in the Flora Palaestina. These findings, combined with the recently-published genetic evidence for these populations significantly advance our understanding of the species' ecology and persistence under climate change.