Essential knowledge for fermentation industry：what is yeast extract？
April 22, 2020
Yeast Extract is a yeast derivative, rich in various amino acids, vitamins and trace elements and other nutrients, so it is widely used in food additive, biopharmaceutical, fermentation and other fields. This article combines multiple papers to explain the definition, source classification of yeast extract, as well as briefly introduce its production process, nutritional ingredients, possible mechanisms, etc. Then, the concept of yeast powder is introduced: compared with yeast extract, yeast powder contains intact cell walls, protein and other nutrient components which are not fully degraded, and it is suitable for microbial fermentation with strong protease secretion ability. I hope that the above content is of guiding significance to all fermentation engineers and researchers.
What is yeast extract? Yeast extract, derived from yeast, utilizes biotechnology to degrade the protein and nucleic acid in the cell under a specific environment, and then prepared as a soluble nutrient source through downstream processing operations such as centrifugation, concentration, filtration, etc. Yeast extracts are usually preserved in paste or powder form. In 1997, the International Hydrolyzed Protein Committee (IHPC) stipulated that the main components of yeast extracts include amino acids, peptides, polypeptides and water-soluble components of yeast cells produced by the decomposition of peptide bonds through natural enzymes which present in edible yeast. Yeast extract can be in the form of liquid, Paste, powder or granules.
●Rich in nutrients such as protein, amino acids, peptides, nucleotides, Vitamin B group, growth factors, trace elements, etc., of which the proportion is harmonious to provide comprehensive and balanced nutrition for microbial fermentation and propagation.
●Meet the increasing demands of the biological industry for organic nitrogen sources, and provide the necessary guarantee for the clean production of fermentation industry.
Classification of biological sources
1. Baker’s yeast extract
Using purely natural high-protein baker's yeast as raw material, the product is rich in nutrients and no impurities, light in color, good in solubility, and easy to extract after the product. It has the characteristics of high efficiency, cleanliness, safety and stability, and meets the safety standards of food and medicine.
2. Brewer’s yeast extract
It uses the by-product beer mud as the raw material after brewing beer, and has certain impurity components. The color is darker and the solubility is not good. The product is rich in nutrition and low in cost. It is suitable for the fermentation of non-food and pharmaceuticals that do not require high cleanliness and safety.
3. Torula yeast extract
Torula yeast extract, from Torula yeast, with high protein content, dark color, common solubility, and speical odor. Torula has strong growth and reproductive ability, and is only suitable for fermentation production without cleanliness and safety requirements.
Production method of yeast extract
1. Acid hydrolysis
Acid hydrolysis is the use of acidic substances to break down yeast cells (mainly using sulfuric acid or hydrochloric acid). However, the post-processing cost of this method is high and the pollution is heavy, so it is basically no longer used in the industrial production of yeast extract.
2. Enzymatic hydrolysis
The enzymatic hydrolysis method is breaking down the yeast by the action of the added enzyme. The technological process is as follows: the enzyme in the yeast cell is inactivated by heating and other methods, and then the exogenous enzyme is added under certain conditions, the content of the yeast cell itself is released under the stimulation of the exogenous enzyme, and is decomposed into small molecules such as amino acids. Then use the downstream process to process the yeast liquid to obtain yeast extract. The advantage of this method is that the obtained yeast extract is of good quality, but it has high requirements for enzyme preparations, so the production cost is high, and it is not commonly used at present.
The autolysis method uses enzymes to decompose and reduce the yeast's own carbohydrates and other substances into small molecules, such as amino acids and peptides. The difference with the enzymatic hydrolysis method is that the raw material of the autolysis method is fresh live yeast with enzyme activity. Production process: First, the yeast cell's own enzyme decomposes and reduces the yeast cell under the cooperation of the autolysis accelerating agent, and then extracts the yeast liquid containing the decomposed small molecule substance, and obtains yeast extract through the downstream process. The advantage of the autolysis method is that the yeast's own enzyme system is used for protein decomposition, the decomposition rate is high, the content of free amino acids is high, and the cost is low.
4. Autolysis-enzyme linked method
Now in Europe, America and China, the autolysis-enzyme-linked method is used, that is, yeast is first degraded under certain specific conditions, and then exogenous enzymes are added to the yeast liquid to convert sugars, proteins and nucleic acids in yeast cells to nutrition or flavor substances. This transformation can not only meet the needs of the food and fermentation industry for new product characteristics, but also has balanced nutrition than traditional yeast autolysates.
Senior manager of Angel Yeast APAC Division
About Angel Microbial Nutrition：
Angel YE, rich in protein, amino acids, peptides, nucleotides, B vitamins and trace elements. With the advantages of having no allergic source and being non-transgenic, high efficiency and stable quality, Angel YE are widely applied in the biological laboratories and industrial-scale fermentation, promoting the product safety and technical progress in the global fermentation industry.
Angel Yeast Company is a high-tech listed company specializing in yeast and biotech. Product business covers Yeast and Baking, Yeast Extract-Savoury, Nutrition & Health and Biotechnology fields. It is one of the world's leading companies in the yeast industry. Angel has 12 holding subsidiaries and provides products and services for more than 150 countries and regions.
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