yeast

Environmental yeasts

Posted on August 12, 2009 by Jackie

Question from Charles Brown:

“does watermelons have there own yeast and grapes/fruits trying to make wine for the first time and my friends say i do not have to get yeast because watermelons/ grape already have yeast, is this true.”

While it is true that there are airborne yeasts everywhere that will cause fermentation to occur naturally, the yeasts in the air vary a lot in quantity and type. You can’t be sure they will make wine from your fruit. Many naturally occurring yeasts will not tolerate a high level of alcohol for instance.

By providing a closed environment for the yeast of your choice to work in, random yeasts are eliminated, and other contaminants are kept to a minimum.

..Still no fermentation

Posted on August 2, 2009 by Jackie

I had a problem first starting the wine off as the temp dropped and the fermentation did not start, so after 3 days I started some more yeast in 500 ml of the juice (once warmed). After an hour and the yeast was activated I add it to the rest in the primary. Temp has been good for two days now but still no fermentation…?

Posted on August 2, 2009 by Jackie

Fermentation does occur naturally. But natural yeasts cause unreliable and unsteady fermentation that is disturbed by any and all changes in temperature. Once these yeasts have died, acetic bacteria invades and turns the wine into vinegar.
Cultivated yeasts are used because they will tolerate higher alcohol levels and continue to work. Although the final character of the wine is affected by the fruit or other flavorings added at the beginning, there is no wine without the yeast.

Yeast can be very fickle, and the preparation of the starter mix is important in getting off to a good start with the brew. Before adding yeast to the must, it is best to get the fermentation going and the yeast active. Adding a small amount of sugar and a warm fluid will do this.

Baker’s yeast, such as you find in cubes or sachets in the supermarket, takes 10 to 20 minutes to be activated. A small, narrow-necked bottle is best to use. Add the yeast, 2 tablespoons of white sugar and enough warm water to fill the bottle half full. Shake the mixture well and use a cotton wool ball to lightly plug the neck. Stand the yeast starter on a surface that can be readily cleaned. Within about 10 minutes, a froth will form.

Use this starter as soon as possible; it will climb out of the bottle if you don’t!

Brewer’s yeasts and wine yeasts come in sachets or inactive mixes. Follow the instructions on the label or prepare as for the Baker’s yeast, but leave 2 to 3 days to activate. Plug the bottle neck loosely with a wad of cotton wool to stop the mix from becoming contaminated while it works.

Tag: yeast

Environmental yeasts

..Still no fermentation

Yeast

see also Environmental Yeasts question ~ Aug 2009