What is the temperature of the yeast?
The temperature range for yeast activity is 4-40 degrees, and the optimal temperature is 25-35 degrees. If the temperature is below 10 degrees or above 45 degrees, the yeast activity will be greatly reduced. Fermentation will stop completely when the temperature reaches below 4 degrees. The yeast will not die even at -60 degrees, but if it exceeds 55 degrees, the yeast will die in a short time. Death within. Therefore, the water temperature for dissolving yeast cannot be too high or too low.
How much yeast to use?
The amount of yeast used varies depending on the type of bread. Generally speaking, the amount of yeast (fresh yeast) for toast is 2, sweet bread is 3-4, and stollen (German Christmas bread) is 10. When making bread, the amount of yeast must be adjusted according to the temperature at the time, the method, the use of auxiliary materials, etc.
When making frozen dough, increase the amount of yeast used. This is because freezing will cause the water inside the yeast to freeze and expand, destroying yeast cells and causing the yeast to die in large numbers, thus reducing the fermentation ability of the yeast. Freezing will kill 20-30% of the yeast. Most frozen dough is made from high-proportion bread. This is because the high proportion of bread contains more sugar, eggs, and fat, which improves the freezing resistance of the dough.
What type of yeast?
Fresh yeast is yeast that is directly compressed into blocks and sold. Usually fresh yeast is sealed in wax paper and does not come into direct contact with the air. Fresh yeast contains 70% moisture. Fresh yeast can be mixed directly with flour, but since it is a solid and difficult to mix evenly, it is best to dissolve the yeast in water before use. When dissolving yeast, please note that sugar, salt, improvers, etc. cannot be added to the yeast solution, and the water temperature for dissolving fresh yeast cannot exceed 40 degrees. Fresh yeast should be kept away from freezing. It can be refrigerated for daily use. The temperature should not exceed 10 degrees. If the yeast is stored at room temperature, it will respire and generate heat. This phenomenon will accelerate as the temperature rises, ultimately affecting fermentation. Because fresh yeast is highly resistant to low temperatures, it is also suitable for use in refrigerated dough dough. In addition, pay attention to cleanliness when using it to avoid the generation of bacteria.
Dry yeast is a granular product made by evaporating and drying the water in the final stage of fresh yeast production in order to improve the shelf life of yeast. Of course, a lot of dead yeast will be produced during drying (4~15). Dry yeast only contains 7-8 moisture and is suitable for low-ratio hard breads such as French bread. This is because the activity of maltase in dry yeast is significantly higher than that of sucrase, so it is more suitable for low-ratio dough dough. Although dry yeast is used, their aroma is obvious during the fermentation stage, but the difference between the two is not very big after baking.
Before using dry yeast, you must soak it in warm water at about 40 degrees for 10-20 minutes 5-6 times, so that the dry yeast can fully absorb the water before stirring. This method is called preparatory fermentation. Like fresh yeast, sugar, salt, improvers, etc. cannot be added to the solution of dry yeast. (A small amount of sugar in solution 1.5-3 can speed up the dissolution of yeast.) Fresh yeast is alive, while dry yeast can be said to be in hibernation. Preparatory fermentation can be understood as the process of waking up yeast from hibernation. The water temperature for dissolving dry yeast and Unlike fresh yeast, be sure to use warm water.
The amount of dry yeast used is about 1/2 of fresh yeast. It should be noted that dry yeast should be used as soon as possible after preparation for fermentation.
Instant dry yeast is granular dry yeast with smaller particles than ordinary dry yeast. The moisture content is only 4~4.5. Instant dry yeast is very active, eliminating the need for pre-fermentation steps and can be directly mixed with flour. However, when making bread with a short fermentation time, sometimes the yeast will not be completely melted into the dough, so it is best to use water first. Dissolve it before use. Instant dry yeast has strong activity and fermentation power, and the usage amount is only 40% of that of fresh yeast.
When using instant dry yeast, please note:
1. Do not directly add water below 15 degrees. If the water temperature is too low, stir the dough for 1 to 2 minutes. Then put the yeast into the dough.
2. It must be stirred for about 5 minutes after being put in. If the stirring time is short, there will be residual yeast particles.
3. Some instant dry yeast has vitamin C added as a protective agent. In this case, there is no need to add vitamin C.
Natural yeast?
The yeast we buy on the market now is yeast that has been cultured and multiplied by a specific yeast strain. Natural yeast refers to yeast cultured and bred based on a variety of yeasts and bacteria attached to fruit shells, grains, vegetables, fruits, etc. Natural yeast contains a variety of yeasts, and each type of yeast produces a different aroma when fermented. Therefore, the bread made by natural yeast tastes significantly better than ordinary yeast. Natural yeast contains not only yeast, but also lactic acid bacteria, acetic acid bacteria and other bacteria. After the activity of these fungi, they will produce organic acids such as lactic acid and acetic acid, so bread made with natural yeast will have a sour taste.