Yeast is a kind of single cell protein with high nutritional value. It contains not only about 50% protein and 6% - 8% nucleic acid, but also rich in vitamins, fats, polysaccharides and minerals. If it is directly discarded and discharged, it will cause waste of resources and environmental pollution. According to statistics, China's beer production has ranked first in the world for 12 consecutive years, of which the beer production in 2005 was 30.6 million tons, and the total dry solid content of waste beer yeast was 45900 tons. However, from January to September 2015, China's total beer output was 38.8611 million tons, and the total dry solid content of beer waste yeast was 58300 tons. In 2015, the output of 2005 was achieved in only three quarters.

Due to the strict restriction of environmental protection law and the huge dry solid output of brewer's waste yeast, the comprehensive utilization of brewer's yeast mud has been highly valued. Generally, there is a carbohydrate shell around yeast cells, which is called yeast cell wall. How to break the wall is an important link in yeast development. As a green and safe preparation, enzyme preparation avoids the disadvantages of the past autolysis method, such as bacterial pollution, long production time, low yield and amino nitrogen; acid hydrolysis method has the disadvantages of poor flavor, high salt content, serious corrosion, large nutrient loss and insecurity. Next, the comprehensive utilization of brewer's yeast mud and the role of enzyme preparation in the development of brewer's yeast mud are briefly introduced.

1. Yeast extract

Yeast extract, also known as yeast extract and yeast gourmet, is rich in a variety of amino acids, among which glutamate, glycine and propionic acid are the main components, and glutamate is dense. Its addition can significantly increase the taste of food, improve the flavor, and make the taste of food stronger.

According to statistics, dry yeast extract accounts for 37% of the whole fresh flavor agent sales volume, and the growth rate is 2% every year. In foreign countries, yeast extract is called the third generation monosodium glutamate. Yeast extract is a kind of yeast cell which can degrade proteins into amino acids and nucleic acids into nucleotides by autolysis, adding yeast hydrolase (a complex enzyme) hydrolysis and other methods, and extract them from yeast cell together with other effective components, such as B vitamins, glutathione (GSH), microelements, etc. it has three major functions: seasoning, nutrition and health care It is a natural compound seasoning that functions in one. It is widely used in various fields of food processing. The main technological processes are: beer yeast mud, sieving, washing sea, separation, pretreatment (debitterness), separation, yeast suspension, autolysis, heating, enzyme digestion, separation, enrichment, yeast extract, spray drying, and finished product.