1) Bread yeast is intended for bread making and it should be used as intended. It can be used for making wines but tends to impart a bready flavor. The same game for brewers yeasts – for making beers.
In general, it can live in a wide range temperature, 0 to 50 ºC. Optimal temperature is 20 to 30 ºC. Optimal range may vary depending on strain. The Sacchromyces bayanus is effective from 45 to 95 ºF.
2) Fermentation process produces heat and might exceed the microorganism’s limit. Room ventilation should be provided.
3) In case of halted/stuck fermentation, the dead yeast releases substances to prevent the growth of another yeast. Introduction of another culture will be successful through the use of Saccharomyces bayanus or other strains capable of restarting stuck fermentations.
4) Use of recommended strain for champagne making won’t work. Champagne like quality can be achieved but the sparkling wine is still not. Champagne are made only in Champagne Region of France.
5) Yeast cannot tolerate too much alcohol. Most will produce about 14% before dying. Higher percentage is achieved by distillation or use of tolerant strains. The famous wine yeast brands Red Star Premier Curvée and Lalvin EC-1118 can tolerate up to 18 percent alcohol. Use Wyeast Eau de Vie if higher alcohol content is desired. It can produce up to 21 percent but reported as slow fermenter. There are few strains able to tolerate up to 70% but the activity is quite slow.
6) Addition of sugar to prepared should be limited up to 40%. Only few strains are able to live in higher sugar concentrations.
7) Juice pH should be between 4 to 4.5. It is the optimal pH range for yeast growth and perhaps limiting to other microorganisms.
8) Unpasteurized and loosely covered juice will ferment naturally. Addition of pure culture is not necessary. It is necessary only if a specific alcohol content and quality are desired. Spontaneous fermentation is likely to yield about six percent alcohol with unexpected taste quality.
9) Yeast require oxygen for growth. It will use the atmospheric oxygen if available or grab the oxygen from a glucose molecule if not. The anaerobic process results to production of alcohol and release of carbon dioxide.
10) Yeast also requires nitrogen for growth and development. Fruit pulp should be included in the prepared juice to provide some nitrogen. Lack of this nutrient will halt fermentation.