What is the acid in the old sour bread?

The sourness of old yeast bread is the sourness of natural fermentation for a long time.

The formula of traditional yeast bread is as follows:

I. Materials

High gluten flour 100g, egg 1 piece, yeast 3g, sugar 8g, butter 5g,

Second, practice

1. Put all the ingredients in the toaster to make dough.

2. Ferment to the surface to form a honeycomb.

3. Mix yeast with all raw materials except butter.

4. Knead the dough evenly, add butter and knead it into fascia.

5. Basically ferment to about twice the size.

6. the dough should be divided into 9 equal parts, and it should not be loose.

7. Twist each part into a long strip, fold it in half, then twist it into a knot and make the head into a circle.

8. Put the bread into the mold and ferment it twice at last.

9. Bake in the oven 180 degrees for 30 minutes, then brush with melted butter.

Extended data:

Precautions:

Baker's yeast produces carbon dioxide and water by decomposing sugar. Without oxygen, carbon dioxide and alcohol will be produced, which will lead to an increase in acidity. So if the sugar content of the raw material is high, the bread will be more sour.

If the raw material or dough is contaminated by heterotrophic bacteria, it is probably the process of yeast fermentation and heterotrophic bacteria metabolism to produce acid.

Oil rancidity, the use of fat components such as margarine, etc. If rancidity occurs, it may also cause bread to be sour.

Yeast dosage, fermentation time, yeast dosage and fermentation time are all parameters that need to be controlled in the fermentation process. If it cannot be controlled within a reasonable range, resulting in excessive fermentation, bread will definitely turn sour.