Using Dried Wine or Beer Yeast
Fermentation is the process by which a microorganism (yeast) converts sugar into alcohol and carbon dioxide gas. All wine, beer and mead makers know that yeast is not an ingredient but a living organism whose role is so critical that without it no wine, beer or mead is possible.
When using dried yeast proper rehydration is perhaps the most critical phase in using dried yeast. The drying stage removes not only extracellular water, but most of the water within the cell and bound to the cell's organelles. In the dryer, the yeast cells shrink and desiccate - a very stressed state for a living organism.
To be functional again, the dried yeast cells must reabsorb all their water. When the dried yeast comes in contact with water (or any other liquid) the cells literally act like dried sponges and suck up the needed water in seconds (water uptake). Not only will yeast cells not disperse very well if not properly rehydrated, they can lose a large amount of cytoplasm, reducing the efficiency of oxygen and nutrient transfer to the cells. This impedes growth and activity resulting in sluggish or stuck fermentations. If the yeast is added directly to sweet must or wort, many cells will rupture and be lost because the environment is too rich during water uptake. Proper rehydration can ensure healthy yeast cells and good fermentation characteristics.
Three Easy Rehydration Steps
1. Using 1/3 cup water at 100 - 110 for each 5 grams of yeast, sprinkle the dried yeast over the water allowing the cell to absorb the water and sink to the bottom, then continue to sprinkle filling in the gaps. If all the yeast is poured in, it will seal itself in a ball and not properly absorb the water.
2. When the all the cells have absorbed water, stir lightly and allow the yeast suspension to stand for at least 15 minutes but no longer than 30 minutes, then stir again.
3. Pour the yeast suspension (inoculation) into a starter or directly into the wort or must and stir vigorously to start the fermentaion.