Yeast is a kind of edible and nutritious single cell microorganism, which has a wide and close relationship with human daily life and industrial application. Yeast is also a kind of micro organism with the earliest utilization, the widest application range and the most direct consumption (in millions of tons) of human beings at present. Active yeast is a kind of pure microbial product with fermentation activity, which is cultivated by bioengineering technology with food and sugar as raw materials.

Yeast is rich in a variety of minerals and microelements, such as calcium, iron, zinc, magnesium, selenium, chromium, manganese and so on. These nutrients exist in the form of life combination, which is not only natural, safe, but also easy to digest and absorb, and has high bioavailability. Selenium is one of the essential microelements for human body. It can resist aging, tumor, arteriosclerosis, Kashin Beck disease, detoxify and improve the immunity of human body. It is the only microelements related to antiviral mutation. There is a low selenium belt from northeast to southwest in China, with a population of about 100 million. Chromium is also one of the essential microelements for human body. The research shows that under the condition of stress, human and animals need more chromium. Lack of chromium will lead to weight loss, peripheral neuritis, and impaired clearance of glucose in plasma. Yeast selenium and yeast chromium are the high quality sources of selenium and chromium.

Yeast has a long history of application in the field of food. People are familiar with the fermentation of wine and flour products. At present, the application of yeast has been extended to medicine, food additives, health food, condiment, feed, culture medium and other aspects.

In view of the unique nutritional and health value of dry yeast, the research on developing various kinds of food and health food around yeast is more and more extensive and in-depth. At present, there are three main directions of yeast development at home and abroad: one is to further develop traditional yeast, improve production technology, reduce production cost of biological enzyme and improve utilization rate of raw materials; the other is to develop biopharmaceutical by expressing exogenous protein through yeast gene; the third is to develop functional yeast that enriches functional factors, and make nutritional yeast and functional yeast after further processing Nutrition and health food.