The role of microorganisms in food manufacturing

1. Application of microbial enzymes in food industry V. Characteristics of microbial enzyme preparations V. Advantages: There are many kinds, which are convenient for industrial production and the output can be large enough to ensure supply. V Disadvantages: A microorganism can produce multiple enzymes at the same time, so the V process is more complicated.

2. Application: 1. 1 vinegar

Vinegar is an acidic condiment made by working people in China in the long-term production practice. It can stimulate appetite and help digestion, which is indispensable in people's diet. Vinegar is also used in Chinese medicine. There are many kinds of vinegar produced all over the country. The famous Shanxi mature vinegar, Zhenjiang aromatic vinegar, Sichuan bran vinegar, Northeast white vinegar, Jiangsu and Zhejiang rose rice vinegar and Fujian red yeast vinegar are representative varieties of vinegar. According to the processing methods, vinegar can be divided into three categories: synthetic vinegar, brewed vinegar and reprocessed vinegar. Among them, fermented vinegar, which has the largest output and the closest relationship with us, is made from starchy raw materials such as grain through microbial koji-making, saccharification, alcohol fermentation and acetic acid fermentation. Besides acetic acid (3% ~ 5%), its main components also contain amino acids, organic acids, sugars, vitamins, alcohols, esters and other nutrients and flavor components, which have unique color, fragrance and taste. It is not only a good condiment, but also very beneficial to health if eaten for a long time.

1. 1. 1 raw materials for production

At present, the main raw materials used in the production of vinegar are: sweet potato, potato and other potatoes; Cereals, such as corn and rice; Broken rice, chaff, chaff and other food processing scraps. ; Fruits and vegetables, such as blackcurrants, grapes, carrots, etc. Wild plants such as acorns and artichokes; Others such as sour wine, sour beer, molasses, etc.

In addition to the above-mentioned main raw materials, the production of vinegar also needs loose materials such as chaff and corncob, so that the fermented materials have good permeability and aerobic microorganisms can grow well.

1.2 fermented dairy products

Fermented dairy products refer to excellent raw milk inoculated with specific microorganisms and fermented to produce food with special flavor, which is called fermented dairy products. They usually have good flavor, high nutritional value and certain health care functions. Widely welcomed by consumers. Commonly used fermented dairy products include yogurt, cheese, sour cream, koumiss and so on.

Fermented dairy products mainly include yogurt and cheese, and the main producing strains are lactic acid bacteria. There are many kinds of lactic acid bacteria, including Lactobacillus casei, Lactobacillus bulgaricus, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus lactis, Lactococcus lactis and Streptococcus thermophilus.

In recent years, with people's understanding of the role of Lactobacillus bifidus in nutrition and health care, people introduced it into yogurt production, which changed the traditional single-plant fermentation into two or three-plant raw fermentation. Because of the introduction of Bifidobacterium, yogurt has the health care function of preventing cancer on the basis of helping digestion and promoting gastrointestinal function. Bifidobacterium is named for its bifurcated tip (such as Y type or V type). Bifidobacterium is a gram-positive bacterium without spores, which is obligate anaerobic, acid-resistant, inactive and negative in catalase reaction. The optimum growth temperature is 37 ~ 465438 0℃. The optimum initial growth ph is pH6.5~7.0, which can decompose sugar. Bifidobacterium can ferment glucose to produce acetic acid and lactic acid (2: 3) without producing CO2. At present, there are 24 known species of Bifidobacterium, 9 of which exist in human intestine. They are Bifidobacterium bifidum (B. bifidum), Bifidobacterium longum (B. brevvis), Bifidobacterium infantis (B. angulatum) and Bifidobacterium catenae (B. adolescentis). Only the first five are used for fermented dairy products.

Bifidobacterium and human body not only "pre-digest" milk nutrients like other lactic acid bacteria in yogurt, but also mainly produce Bifidobacterium, which hydrolyzes lactose and protein in fresh milk into small molecules that are more easily absorbed and utilized by human body. It has obvious killing effect on intestinal pathogenic bacteria, such as Salmonella, Staphylococcus aureus and Shigella. Bifidobacterium in milk can also decompose N- nitrosamine, a carcinogen accumulated in the stomach and intestines, prevent intestinal carcinogenesis, and activate NK cells, promote the production of immunoglobulin, activate the function of macrophages, improve human immunity, and enhance human resistance and immunity to cancer by inducing interferon and mitogen.

At present, there are many kinds of fermented dairy products, such as yogurt, drinks, cheese, cheese and so on. The production technology of Bifidobacterium yogurt is simply introduced.

Bifidobacterium yogurt has two different production processes. One is the co-fermentation process of Bifidobacterium bifidum, Streptococcus thermophilus and Lactobacillus bulgaricus, which is called co-fermentation method. The other is to mix Bifidobacterium bifidum and facultative anaerobic yeast in skim milk at the same time, and use the respiration of yeast in the growth process to consume oxygen through biological methods to create an anaerobic environment suitable for the growth and reproduction of Bifidobacterium, which is called * * * raw fermentation method.

1.3 amino acid fermentation

1.3. 1 overview

Amino acids are the basic components of protein. Among them, 8 kinds of amino acids are essential amino acids that cannot be synthesized by human body, which are called essential amino acids. The human body can only get them through food. In addition, in the food industry, amino acids can be used as seasonings, such as sodium glutamate, sodium inosine and sodium guanosine, and tryptophan and glycine can be used as sweeteners. Adding certain amino acids to food can improve its nutritional value. Therefore, the production of amino acids is of great significance. Table 7~ 1 lists some strains used for amino acid production.

Since 1960s, glutamic acid has been successfully produced by direct fermentation of sugar by microorganisms and put into industrial production. China has become the largest producer of monosodium glutamate in the world. Monosodium glutamate has become one of the important members of condiment, and the research and production of amino acids have developed rapidly. With the progress of science and technology, traditional technology has been constantly transformed, but how to maintain the unique flavor of traditional technology production and make the products produced by new technology more attractive is the subject of future research.

1.5 xanthan gum

1.5. 1 overview

Xanthan gum, also known as xanthan gum, is a new fermentation product developed in 1970s. It is a microbial macromolecular acidic extracellular heteropolysaccharide obtained by Xanthomonas campestris in Gan Lan with carbohydrates as the main raw material through ventilation fermentation, separation and purification. As a new and excellent natural food additive, its application is more and more extensive.

Internationally, the earliest development and application of xanthan gum is the United States. Xanthan gum was first obtained by microbial fermentation in Pioria Laboratory in the northern part of the United States Department of Agriculture in the early 1960s. 1964, Keco Branch of Merck Company of the United States realized the industrial production of xanthan gum for the first time in the world. 1979 The total output of xanthan gum in the world was 2000t, and 1990 reached more than 4000t. In the United States, the annual output value of xanthan gum is about 500 million dollars, second only to the annual output value of antibiotics and solvents, ranking third among fermented products.

The research on xanthan gum in China started late, and research institutions such as Nankai University, Institute of Microbiology of Chinese Academy of Sciences and Shandong Institute of Food Fermentation have all passed the pilot test. At present, there are several xanthan gum production plants in Yantai, Jinhu and Wulian with an annual output of about 200t, which are mainly used as food additives. The starch consumption of xanthan gum production in China is generally about 5%, the fermentation period is 72~96h, and the gum production is 30 ~ 40g/L. Compared with foreign countries, the production level is low. With the further development of xanthan gum production and application, new xanthan gum production plants have been built in Beijing, Sichuan, Zhengzhou, Suzhou and Shandong, which indicates that xanthan gum production in China will present a new situation.

Application of yeast in food manufacturing

Yeast has a very close relationship with people's lives. For thousands of years, working people have made many nutritious and delicious foods and drinks with yeast. At present, yeast plays an extremely important role in food industry. There are many kinds of food produced by yeast. Here are just a few main products.

2. 1 bread

Bread is the staple food in wheat-producing countries, and almost all countries in the world produce bread. It is a fermented food with flour as the main raw material and yeast, sugar, oil and eggs as the auxiliary materials. Rich in nutrition, fluffy in tissue, easy to digest and absorb, convenient to eat, and deeply loved by consumers.

Yeast is an essential biological softener in bread production. Baker's yeast is a unicellular organism, belonging to fungi, and its scientific name is beer yeast. Baker's yeast has many forms, such as round and oval. It is better to produce oval ones. Yeast is a facultative anaerobic microorganism which can ferment under aerobic and anaerobic conditions.

2.2 brewing

China is a big country of wine production and an ancient country of wine culture civilization, which plays an important role in the field of using yeast to make wine. Many unique brewing technologies are unique in the world, praised by countries all over the world, and have also made important contributions to China's economic prosperity.

Brewing has a long history, and there are many kinds of products, including yellow wine, white wine, beer, fruit wine and so on. But also formed various types of famous wines, such as Shaoxing yellow wine, Guizhou Moutai, Tsingtao beer and so on. Different varieties of wine have different yeasts and brewing techniques, and the same type of wine also has its own unique techniques.

beer

Beer is a kind of beverage wine containing CO2, low alcohol concentration and various nutrients, which is made of high-quality barley malt as the main raw material and rice and hops as the auxiliary materials through malting, saccharification and beer yeast fermentation. This is one of the most productive wines in the world.

3. 1 mold strain for production

Starch saccharification and protein hydrolysis are carried out by amylase and protein hydrolase produced by mold. Usually, mold culture is first carried out to make sake koji. Starch and protein were cooked and gelatinized, then seed koji was added and cultured at a certain temperature. Various enzymes produced by molds in distiller's yeast decompose starch and protein into hydrolysis products, such as sugar and amino acids.

There are many kinds of saccharifying strains using mold in production. Rhizopus Japonicus AS3. Rhizopus oryzae and Rhizopus chinensis are commonly used in Rhizopus. Aspergillus Niger, Asp. Usami, Asp. Mi and Asp. Paosheng is usually used in Aspergillus. Mucor rouxii is commonly used in the genus Mucor, and some species of monascus are also good saccharifying agents, such as monascus. Purple red, monascus. Anka, monascus. Monascus and Monascus variegata.

3.2 sauce

Sauces, including soy sauce, bean paste, flour paste, soybean paste, lobster sauce and their processed products, are all made from some grain and oil crops as the main raw materials and fermented by microorganisms mainly Aspergillus oryzae. Sauce fermented products are nutritious and easy to digest and absorb, and can be used as side dishes and condiments. They have unique color, fragrance, taste and low price, so they are popular and popular condiments.

The mold used in soy sauce production is mainly Aspergillus oryzae, and commonly used in production are Shanghai Brewing 3.042, Aspergillus flavus Cr- 1 strain (which does not produce toxin) and Aspergillus Niger (Asp. Nigerf-27) and so on. Aspergillus used has strong protease, amylase and cellulase activities. They decompose protein in raw materials into amino acids, starch into sugars, and alcohols, acids and esters. It is produced under the interaction of other microorganisms, forming the unique flavor of the sauce.

3.3 soy sauce

Soy sauce is a kind of food seasoning commonly used by people, which is rich in nutrition and delicious. It has a history of more than two thousand years in China. It is made from protein raw materials (such as bean cake and bean cypress) and starchy raw materials (such as bran, flour and wheat) by co-fermentation with microorganisms such as Aspergillus.

Aspergillus oryzae, Aspergillus flavus and Aspergillus Niger are commonly used in soy sauce production. Aspergillus strains used in soy sauce production should meet the following conditions: no aflatoxin; The activities of protease and amylase are high, and the activity of glutamine is high; Rapid growth, extensive culture conditions, strong resistance to miscellaneous bacteria; No peculiar smell is produced, and the sauce products brewed by koji-making have good flavor.

1923, American scientists successfully developed citric acid fermentation with waste molasses as raw material and established a factory for production. 195 1 year, for the first time, American Myers Company used submerged fermentation to produce citric acid on a large scale. Citric acid was successfully produced by submerged fermentation of dried potatoes in China from 65438 to 0968, and many microorganisms can produce malic acid.

Main microbial enzyme preparations in food processing and their applications

As a biocatalyst, enzyme has attracted more and more attention and been widely used because of its high catalytic efficiency, mild reaction conditions and strong specificity. Many kinds of biological enzymes have been found in biology, and only a dozen of them are widely used in production, such as amylase, protease, pectinase, lipase, cellulase, glucose isomerase, glucose oxidase and so on. It is easier to produce biological enzyme preparations by microorganisms than to obtain them from plants, fruits, seeds and animal tissues. Due to the limited sources of animals and plants, limited by seasons, climate and regions, microorganisms are not only unaffected by these factors, but also have a wide variety, fast growth rate, easy processing and purification, and relatively low processing cost, which fully shows the advantages of microbial production of enzyme preparations. Now, except for a few enzymes still extracted from animals and plants, most of them are produced by microorganisms.

4. 1 Main enzyme preparations, uses and enzyme-producing microorganisms

Enzyme preparation can be produced by bacteria, yeast, mold, actinomycetes and other microorganisms.

3. Application of1enzyme preparation in food preservation

With the continuous improvement of people's requirements for food and the continuous progress of science and technology, a brand-new food preservation technology-enzyme preservation technology is emerging. Enzymatic preservation technology is a technology that uses the efficient catalysis of biological enzymes to prevent or eliminate the adverse effects of external factors on food, thus maintaining the original excellent quality and characteristics of food. Because of its strong specificity, high catalytic efficiency and mild reaction conditions, enzyme can be widely used in the preservation of various foods, effectively preventing the adverse effects of external factors, especially oxidation and microorganisms.

Glucose oxidase is an oxidoreductase, which can catalyze the reaction between glucose and oxygen to produce gluconic acid and hydrogen peroxide. Putting glucose oxidase and food in a sealed container can effectively reduce or eliminate oxygen in the sealed container in the presence of glucose, thus effectively preventing the oxidation of food components and playing a role in food preservation.

Application of enzyme preparation in starch food production

Starch-based food refers to the food containing a lot of starch or processed with starch as the main raw material, which is the largest food in the world. Starch can be hydrolyzed into dextrin, oligosaccharide, maltodextrin and glucose. These products can be further transformed into other products. In the production of these products, various enzymes are widely used.

A variety of enzymes are widely used in the processing of starchy foods, among which α-amylase, β-amylase, glucoamylase, pullulanase and glucose isomerase are the main ones. At present, most glucose production at home and abroad adopts amylase hydrolysis method. Enzymatic production of glucose takes starch as raw material, liquefied by α -amylase into dextrin, and then produced by glucoamylase. Fructose syrup is a mixed syrup containing glucose and fructose, which is catalyzed by glucose isomerase to produce fructose.