In the process of dough fermentation, bread yeast is in the special physiological environment of rapid change from aerobic to micro aerobic, which requires bread yeast must have the following basic characteristics: 1.(2) the ability to quickly adapt to substrate changes;(3) has the appropriate sucrase (or other hydrolytic enzyme) activity;(4) has a potentially high maltose fermentation speed;(5) have the ability to synthesize enzymes and coenzymes necessary for living under anaerobic conditions.
In addition, rapid growth rate (rapid fermentation ability) under suitable conditions, tolerance to high sucrose concentration at the beginning of dough fermentation (hyperosmosis resistance) and wide pH adaptability required by the use of acidic additives are also considered desirable characteristics.Among the many characteristics of bread yeast, the fermentability is undoubtedly the most important index to measure the quality of bread yeast.Only when the fermenting power of yeast reaches a certain index can it meet the technological requirements of bread production.Good bread yeast should have good fermentation performance, which is reflected in its fast fermentation speed and high gas production capacity in both sugar-free dough and high-sugar dough.Having higher specific growth rate and faster reproduction speed;In the high sugar environment has a short delay time, the growth is fast.
Recently, under the condition of the refrigerator may terminate refrigerated manufacture bread dough fermentation metabolic technology (Refrigerateddoughprocess) development by the new focus on frozen dough method is similar to that of a previously been developed.In this technique, dough is temporarily refrigerated, taken out when necessary, and fermented and baked.This requires that bread yeast species have good adaptability to low temperature.
As for the production index of bread yeast, it is often measured by the yeast's gas production capacity in dough, storage resistance, resistance to high concentration of salt and sugar and productivity (productivity is the biomass obtained per unit substrate).In addition, the flocculation ability of bread yeast cells has important application value in the post-processing process of bread yeast production. Good flocculation ability can reduce the energy consumption in the post-processing and recovery process.