2. Excessive stirring or the dough does not stir out gluten.

3. Too much sugar will lead to too high osmotic pressure and inhibit the activity of yeast. Generally speaking, the sugar content in bread should not exceed 22% of flour.

4. Too much salt can also inhibit the activity of yeast.

5. Too low temperature will lead to low activity of yeast, and the favorite temperature of yeast is 28~30℃.

6. The dough is too wet and sticky.

Extended data:

1. Nutritional value of fermented pasta

Dough fermentation generally adopts yeast fermentation, dough fermentation, baking soda fermentation and compound starter fermentation. These methods all produce a lot of gas in the dough during fermentation, and then steam it, and the gas expands when heated, so the steamed bread and bread made are soft and delicious. However, dough fermentation will produce sour taste, which will destroy the nutrition of pasta if neutralized with alkali.

Baking soda will destroy B vitamins in flour, while compound leavening agent generally contains aluminum which is harmful to human health. Only pasta fermented by yeast will greatly increase the nutritional value of steamed bread and bread. Because yeast contains many vitamins, minerals and enzymes besides protein, carbohydrates and fat. The nutritional content of steamed bread and bread made by yeast fermentation is much higher than that of unfermented pasta such as pie and noodles.

Seven points that can't be ignored in controlling fermentation:

Bread fermentation is a process in which yeast takes sugar as food and converts sugar into carbon dioxide and ethanol. In this process, the sugar in the compound starch molecules in flour is released. Properly fermented dough can fully release sugar that can adjust the taste and color, and at the same time leave enough starch and protein to keep the best texture, so that the taste, appearance and texture of bread can reach the best state.

① temperature

We know that controlling the dough temperature and fermentation temperature is the most important step in the fermentation process. If the temperature is too high, the yeast will ferment ahead of time before gluten is formed, and the bread texture will be poor. If the temperature exceeds 60℃, the yeast has been killed and cannot function.

Optimum fermentation temperature: the optimum fermentation temperature of bread is 25-35℃, the optimum temperature of main fermentation is 25-27℃, and the optimum temperature of secondary fermentation is 32-35℃. If the high temperature and yeast ferment too fast, it will make you easily lose control of the dough and bake low-quality bread.

Control the dough temperature: control the final dough temperature by controlling the material and room temperature. Using the following formula, the dough temperature can be calculated, or the liquid temperature can be calculated by knowing the dough temperature.

The dough temperature should be controlled within the set temperature of 2℃ as far as possible, so that we can control the time change within 5- 10 minutes according to the preset fermentation time of the formula. Generally speaking, if the fermentation temperature is increased by 8℃, the fermentation time will be reduced by about half.

② Humidity

The optimum humidity of dough fermentation environment is 70%-85%. In the process of fermentation, the humidity of dough must be kept. If the air is very dry, a layer of "shell" will form on the surface of dough, which will hinder the expansion of dough, affect the quality of finished products, and make dough hard and difficult to chew.

In addition to using professional fermentation boxes, we also have the following methods to control the humidity of dough in home baking:

A. Use plastic wrap: when fermenting, cover the dough with plastic wrap to avoid excessive contact with air;

B. Use the fermentation function of the oven: use the fermentation function of the oven, or turn on the baking at low temperature (about 40℃), turn off the baking, put the dough in the oven, and put a cup of boiling water next to the dough to increase the humidity. You can also turn on the oven light to raise the fermentation temperature.

C. Use the microwave oven to form a closed space: put a cup of hot water first, then add the dough, and turn off the microwave oven to create a moist space.

③? time

Controlling fermentation time is mainly to avoid insufficient fermentation or excessive fermentation, which will lead to poor bread expansion and tissue hardening; Excessive fermentation makes bread easy to collapse and shrink. After controlling the fermentation temperature, if you are not sure about the fermentation time, you can use the finger pressure test to check the fermentation of dough every half hour.

Finger pressure test: insert your finger into the center of the dough and pull it out. If the dough rebounds quickly, it means that the fermentation is insufficient. When dough collapses, it is over-fermented. Slow rebound of dough means proper fermentation.

④ Use fermentation tools.

It is also meaningful to choose fermentation tools to help fermentation. The fermentation container is generally 2-3 times larger than the dough to prevent the dough from overflowing when the container is too small. Among the fermentation tools, the utilization ratio of fermentation basket and fermentation cloth is the highest:

In addition to making country bread, the fermentation basket can also form beautiful patterns and help the dough to be fully proofed.

Fermented cloth plays an important role in soft dough processing. It can form a "wall" to prevent the dough from spreading or flattening to both sides.

⑤ Differentiated use of yeast

In bread, there is a principle that fermentation is completed with the least yeast. Too much yeast will accelerate dough fermentation, but at the same time, it will consume available sugar and leave the smell of alcohol. Because yeast is thirsty for sugar, after the sugar in flour is decomposed, it will begin to decompose itself, producing a by-product called glutathione, which will produce an odor similar to ammonia and weaken the strength of gluten.

⑥ Control the use of salt and sugar.

In fermentation, too much salt or sugar will reduce the activity of yeast, which is also the reason for the long shelf life of pickled food-salt reduces the activity of bacteria. In polysaccharide environment, yeast will decompose monosaccharide first, and then starch in grain, so sugar should not be excessive. In dough, the amount of salt is generally not more than 2% (baking percentage), and sugar is generally not more than 30% (baking percentage).

⑦ Understand the significance of secondary fermentation.

In some instant bread, baking is only done once, but most bread needs secondary fermentation for the following reasons:

Answer? Before the second fermentation, it will exhaust the carbon dioxide produced in the first fermentation and supplement new oxygen to improve the activity of yeast.

b？ Make the surface temperature of dough closer to the internal temperature and make the fermentation more complete;

c？ Gluten is strengthened again through the kneading process.

Reference: Baidu Encyclopedia-Fermentation