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July 2018 WINES&VINES 43 WINEMAKING help in the process of drying and later rehydra- tion. The emulsifier is a plant oil that aids water transport into the cells. A fluid bed dryer is utilized during the drying process so that the cells are dried in a gentle manner in order to protect them as much as possible. Fermentis validates the drying process by rehydrating some of the yeast cells in a sugar- water solution at temperatures ranging from 10°C to 30°C while assuring their residual vi- ability. Micro-vinifications are conducted to confirm the aromatic and structural character- istics and to be sure nothing has changed in their organoleptic qualities. The E2U process encompasses two parts: industrial production of sustained genetic, physiological and structural qualities, and then the creation of a dried product that can with- stand the rigors of rehydration. Informational materials published by Fermentis include fer- mentation curves comparing standard rehydra- tion methods of the same strains with those following the E2U protocols. The results show that both the standard methods and the E2U protocols to have the same performance characteristics. The yeast review project As of 2018, the E2U group of yeast encom- passes seven different strains with different characteristics, which gives the winemaker a range of choices for products as varied as sparkling wines and high alcohol wines. Some strains express strong thiol production, while others express strong ester production. There also is a mix of nutrient requirements from low to high levels. As part of the project started in 2016, Fer- mentis compared the performance of different yeast strains with respect to many organoleptic and analytic qualities with nutrient conditions. Figure 1 shows the analytic results in a set of three graphs. Figure 1 shows the Odor Active Value (OAV), which is a compounds concentra- tion/perception threshold. These values are standardized on a 0 to 10 scale. Note that the SafŒno GV S107 and the SafŒno VR 44 are not E2U in all three graphs in Figure 1. Comparison of Figure 1a with Figure 1b demonstrates the effect of Yeast Available Ni- trogen (YAN) deficiency with that deficiency corrected in 1b from the nutrient level of 1a. In the case of Figure 1b and 1c, ethyl esters were enhanced at varying levels, no matter whether YAN was deficient and corrected or if YAN was normal and additional nutrients added. These graphs indicate that the ability of the yeast to add additional compounds is strongly linked to nutrient concentration and, therefore, can be controlled by the winemaker. The organoleptic results are shown in spi- der graphs in Figure 2. These results are quite different when compared with the analytical results. For example, the thiols with YAN defi- ciency and recommended adjustments in Fig- ure 2b show marked decreases in Fresh/Ripe Fruits and Reduction/Oxidation and increases in Fruity/Amylic, Vegetal, Floral and Mineral characteristics. The esters on the right side of the spider graph in Figure 2c are generally enhanced in all traits on the Reduction/Oxida- tion and Fruity/Amylic axis and virtually non- existent on the left side. This set of conditions shown in both figures indicate that winemakers have control over a wide range of aromas, flavors and the balance in the wines produced with these strains. An independent yeast trial Fermentis provided SafŒno HD S135 and SafŒno CK S102 yeasts so that I could conduct independent lab trials. March and April are not the best months to do fermentation trials, and consequently I was not surprised to have vari- able results on small scale fermentations. The good news was that the lab trials generally followed the data from the curves presented at the EnoForum meeting discussed above. Fortunately, I did have a client who needed a larger scale fermentation (2,000L) for both white and red wines. These two wines were OPTIMIZED YEAST REHYDR ATION TO REVEAL YOUR GR APES POTENTIAL The evolution of yeast protection: Increase yeast vitality Increase yeast ethanol tolerance No more oxygen addition worries with white and rosé ferments Improves yeast aroma precursor use www.scottlab.com LALLEMAND OENOLOGY