Temperature: in a certain temperature range, with the increase of temperature, yeast fermentation speed will increase, gas production will increase, but the highest do not exceed 38 ℃ ~ 39 ℃.Normal temperature should be controlled within 26 ℃ ~ 28 ℃, if use rapid production law of not more than 30 ℃, because more than the temperature, the fermentation tachycardia, not fully mature, the dough cover gas ability is poor, affect the quality of the final product.
PH value: the PH value of dough is best between 4 and 6.
Effects of sugar: the sugar that yeast can directly use is glucose, fructose.Sucrose, on the other hand, is broken down into glucose and fructose by enzymes in yeast, which provide energy for fermentation.Maltose, also known as maltose, is produced by breaking down the starch in flour with an enzyme called amylase. Maltose in yeast is converted into 2 molecules of glucose, which can also be used.
Osmotic pressure: osmotic pressure refers to the amount of extra pressure added to the solution to prevent osmosis. The osmotic pressure of the external medium has a great impact on the vitality of yeast.Because the outer membrane of yeast cell is a semi-permeable membrane, which has osmotic effect, the concentration of external media will directly affect the vitality of yeast. High concentration of sugar, salt, inorganic salt and other soluble solid substances will cause high osmotic pressure and inhibit the fermentation of yeast.The reason is that when the concentration of the external medium is high, the protozoa in the yeast exudes the cell membrane and the protoplasm is separated. As a result, the yeast is destroyed and unable to survive.In this respect, dry yeast is more adaptable than fresh yeast.Of course, some yeasts can survive and ferment at high concentrations.
In bread production, the main factors influencing osmotic pressure are sugar and salt.When the amount of sugar in the formula is 0 ~ 5%, it does not inhibit the fermentation of yeast, but can promote the fermentation of yeast.When it exceeds 6%, it inhibits fermentation, and when it exceeds 10%, it slows down significantly. In glucose, fructose, sucrose and maltose, the inhibition of maltose is less than that of the first three sugars, because the osmotic pressure of maltose is lower than that of other sugars.