Research Of Active Dry Yeast’s Fermentation Force Attenuation Mechanism

The baker’s yeast is a kind of single-cell real nucleolus microorganism, belonging to one of Saccharomyces cerevisiae. It is benefit to human beings, also it is one types of the earliest microorganism which is applied on practice medium. In addition, it is an important microorganism on modem ferments industry. It makes use of fermentable sugar which is in paste and trehalose or glycogen to grow and breed, producing CO2to make the paste loosen. Then, the baker’s yeast is theindispens ability microbial loose thing and also is the basic material. The production of the baker’s yeast has already had the history of more than200years up to now.The high active dry yeast is on the form of solid. It has three basic characters:first, it can keep activity in normal temperature; second, after activition it can resume normal fermental ability; third, the cell content is more than200hundred million cfu/g, the water content is less than6.0%. Otherwise, it has other advantages, such as the long store time, conveniently using.Currently, the high active dry yeast’s row material is glucose molasses. But this technique is still not mature. After dehydrating to process, there are many disadvantages, such as the low fermental ability, not bear to dry, the low preservative ability, the short shelf period etc. Therefore? the main contents of this topic is to improve the fermental and preservative abilities of the high active dry yeast.The topic mainly studies the difference of the different raw material’s composition, measuresing its physics and chemistry characters, studying damply extent of dry yeast, influence. What’s more, influence of the dry temperature and preservative method. At the last, we call find the optimum condition.The main results are as follow:The glucose molasses contain a few microelements and doesn’t have abundant nutrition; the cell grain isn’t full, unsymmetrical and impure, also broken degree is big; The microelements which are benefit for preservative ability in the dry yeast cell are few, such as Mn, Fe, Zn etc. Therefore, the fermental ability of the active dry yeast is low and the product don’t sustain to reserve. But the nitrogen, phosphorus, trehalose and water content are important factors. The study indicates:the trehalose content is12%～14%, phosphorus content(with the P205calculation)is30"-’40%of the amount of nitrogen, the water content is5.0-6.0%, in this condition there is a great fermental ability and stability. Adding to2.5%SP60and2.0%vitamin C plays all important part in protection function. By studying the physics and chemistry characteristics of active dry yeast, dry temperature, preservative temperature, packing method and SO on, we can find:the buff and uniformity active dry yeast which is under40℃dry temperature,-4℃, vacuumize and nitrogen pack Can achieve high fermental ability and preservative efficiency. With the optimum experiments between extration analysis and response surface method, we have the results:the content of water is5.5%, the density of SP60iS2.6%, the density of vitamin C is2.0%, the dry temperature is40℃. There ale many improvements in the high active dry yeast’s fermental ability and preservative ability.