experimental materials

Medium gluten flour, yeast, lard, warm water.

Dough surface

Unfermented, incompletely fermented, successfully fermented and over-fermented, except for the volume, there is no obvious difference.

Dough part

Unfermented: The dough is compact and has a few pores.

Incomplete fermentation: the dough began to swell and the pores increased.

Successful fermentation: the dough is soft and swollen, and can rebound after pressing, with uniform pore size and distribution.

Overfermentation: the dough is soft and swollen, does not rebound after pressing, and some oversized pores are unevenly distributed.

Steamed bread surface

Unfermented-uneven surface.

Not fully fermented-hot spots on the surface.

Successful fermentation-smooth surface.

Overpenetration-the surface shrinks inward.

Overpenetration-smooth surface.

Steamed bread noodles

Unfermented-small in size and hard in taste.

Not completely fermented-some places are hard and some places are fluffy.

Successful fermentation-large volume, soft and fluffy, spongy texture.

Steamed bread noodles

Over-fermentation-the volume is reduced after opening the lid, and the taste and texture are hard.

Overfermentation-the epidermis is separated from the internal tissue, and the taste is soft and fluffy.

Internal structure of fermented dough

Reticular gluten structure, pore holding.

It was easy to steam out the smooth and round steamed bread, and it all retracted as soon as it was opened! Generally speaking, the reason is that fermentation is not in place, which can not explain all kinds of unexpected phenomena, because fermentation failure is also divided into many situations.

Experimental principle

Flour and yeast are very important raw materials for making steamed bread. When flour is mixed with water, protein molecules in flour are interconnected to form a crisscross network structure, which is gluten; At the same time, yeast continuously decomposes sugar and produces carbon dioxide gas. The pressure generated by these gases pushes the gluten to stretch continuously. In turn, gluten wraps the gas to prevent it from escaping. So the dough keeps expanding in the game between them.

Successful fermented dough has two abilities: gas-producing ability (from yeast) and gas-holding ability (from gluten), which are equivalent. If the gas-producing ability of yeast is insufficient and the gas-holding ability of gluten is too strong, the steamed bread will be hard; Yeast can produce gas, but the gas holding capacity of gluten is insufficient, so steamed bread may collapse or even shrink.

It is often said that steamed bread died because the gas produced by yeast could not push gluten away. At this time, it is necessary to check the dosage and activity of yeast. On the premise of confirming the activity, generally prolonging the fermentation time can solve the problem that the dough does not ferment. Also remember to choose medium gluten flour, gluten strength is suitable for steamed bread.

In successfully fermented steamed bread, the gas-holding capacity of gluten and the gas-producing capacity of yeast are maintained in a balanced state. After fermentation, the gluten and pores in the dough are evenly distributed, and the steamed internal structure is like a fluffy sponge. Even if it is squeezed, it can rebound spontaneously.

However, over-fermented steamed bread is often easy to retract or collapse; Its situation is also much more complicated, which may be caused by factors such as flour quality, water addition, yeast activity, fermentation temperature and cooking conditions. This is also the reason why the solution to the same problem of steamed bread retraction is varied and different.

The essence of steamed bread shrinkage is that gluten is not strong enough to retain gas or support structure. When the yeast produces too much gas and the pressure is too high, the strength of gluten is reduced due to excessive stretching, or even broken by gas, and the distribution of pores and gluten in dough is uneven, steamed bread is easy to shrink back.

Finger pressure can preliminarily judge whether dough fermentation is successful or not. If the dough can rebound slowly after pressing, it shows that a stable gluten structure has been formed; If there is depression, it is likely to be over-fermentation. A simple rescue measure is to let the dough stand and wake up after the air is exhausted, waiting for a stable gluten structure to form.