How to avoid pollution in solid fermentation? urgent

Solid-state fermentation refers to the biological reaction process carried out by one or more microorganisms in an underwater soluble solid matrix with certain humidity and no or almost no free water. Considering the nature of biological reaction, solid-state fermentation is a biological reaction process with gas phase as continuous phase. Solid state fermentation has the advantages of simple operation, low energy consumption, easy control of fermentation process, relatively low requirements for sterility, and difficulty in large-scale pollution.

Solid fermentation

Broadly speaking, microorganisms grow on water-insoluble substrates, which contain different amounts of free water. Narrow sense: Microorganisms grow on moist and water-insoluble substrates for fermentation, and solid fermentation does not contain any free water. With the increase of free water produced by microorganisms, the scope of solid fermentation extends to viscous fermentation and solid particle suspension fermentation.

The advantages of editing this paragraph

1. The culture medium is simple, such as grain, wheat bran, wheat straw, bulk grain or agricultural products. The cost of fermentation raw materials is economical. 2. Substrate pretreatment is less than liquid fermentation, such as simply adding water to moisten the substrate, or simply grinding the substrate to increase the contact area, without special equipment, which can be carried out by ordinary families. 3. Because taking water can reduce the pollution of miscellaneous bacteria, this low sterilization step can be used for fermentation and is suitable for low-tech areas. 4. It can produce special products, such as the red pigment produced by monascus is ten times that produced by liquid fermentation, and the glucosidase produced by Aspergillus in solid fermentation is more heat-resistant than that produced by liquid fermentation. 5. Solid fermentation is equivalent to using a relatively high culture medium, which can be fermented in a smaller reactor, and the output per unit volume is higher than that of liquid. 6. Downstream recovery and purification processes and waste treatment are usually simplified or simple, and the whole substrate is often used. If it is used as a feed additive, it does not need to be recycled and purified, and there is no waste problem. 7. Solid fermentation can produce special flavor and improve the nutritional value of food. For example, Tianpei can be used as a substitute for meat, and its amino acids and fatty acids are easily digested and absorbed by the human body.

The shortcomings of editing this paragraph

1. is limited to microorganisms growing in low humidity, so the possible processes and products are limited, and it is generally suitable for fungi. 2. When fermenting in dense environment, the removal of metabolic heat will often cause problems, especially in large-scale production, which will often limit its large-scale productivity. 3. It is difficult to detect all the parameters in solid state, especially the probe of liquid fermentation is not suitable for solid fermentation, and it is difficult to adjust and control pH value, humidity and substrate concentration, and it is difficult to measure biomass, and the fermentation conditions of each batch are inconsistent and the reproducibility is poor. 4. Mixing is not easy to transfer mass, so the addition of substances during fermentation is not uniform. 5. Because it is not easy to detect, from the perspective of fermentation engineering, a lot of work is only qualitative or observational, so it is difficult to design a reactor, and it is difficult to quantify production or design a reasonable fermentation process. 6. Solid fermentation takes a long time, and the yield and productivity are often lower than that of liquid fermentation. 7. Because of its high viscosity, the extracted products are usually difficult to concentrate in large quantities.

In this paragraph, edit the advantages of fungi in solid fermentation.

1. It can grow at low water content (the activity of adapting to water is 0.7-0.93-0.98), while the activity of adapting to water by bacterial yeast is more than 0.99. 2. Bacteria are generally difficult to grow at low pH value, while fungi grow well at low pH value ... and the pH value of solid culture medium is difficult to control, so this characteristic of fungi is beneficial to solid fermentation. 3. Solid substrates are usually macromolecular compounds, such as starch, cellulose, hemicellulose, pectin, lignin, protein, lipids, etc. Fungi can often secrete these extracellular enzymes and use the surrounding culture substrates as carbon and nitrogen sources. 4. If fungi have sporulation characteristics, they are easy to store and inoculate, and personnel can inoculate spores without too much training. 5. The growth mode of mycelium is better than that of single cell. The top of the mycelium extends and branches to produce a new mycelium end, which can quickly cover the surface of the solid substrate and effectively use the substrate. 6. If hyphae are separated, substances can be transmitted through pores, and the pores will be automatically closed in case of danger to avoid the loss of cytoplasm; If there is no partition, the substances in the cytoplasm are quickly transferred, which makes the colonies multiply rapidly. 7. The growth of mycelium has a strong force to penetrate into the solid medium, forming a high mechanical pressure, and it is easy to penetrate into the solid medium with the hydrolase secreted by the tip.

Edit the technical improvement of solid fermentation in this section.

Solid culture is a method of inoculating microorganisms on the surface of solid medium for growth and reproduction, which is called solid culture. It is a surface culture. Widely used to cultivate gas microorganisms. For example, agar slant culture for observation or preservation of microbial morphology and plate culture for separation or counting of living cells belong to solid surface culture method. When aerobic microorganisms are prepared by this method, there are the following characteristics: first, most cells overlap and reproduce, so cells that directly contact the culture medium will regrow on this cell to varying degrees; Secondly, from the point of view of nutrient intake, the cells growing on it get nutrients by being close to the pores between cells; Thirdly, from the aspect of oxygen supply, an anoxic environment is gradually formed from the outside to the inside. Therefore, it can be considered that the growth environment between each cell is not necessarily the same. In order to improve the culture efficiency, the method of increasing the surface area was adopted. In the laboratory, inclined test tubes, Petri dishes, triangular bottles and kjeldahl bottles are generally used for culture, while in the factory, curved plates, curtains and ventilated koji-making tanks are mostly used, especially for mold culture. At present, the solid culture koji-making method is still used. Because agricultural and sideline products, such as bran, are selected as raw materials, which are low in price, large in particle surface area, loose and breathable, and easy to obtain in large quantities, they are widely used in the brewing industry. However, because there are still many difficulties in large-scale surface culture technology, liquid surface culture can be used in fermentation production, and most of them are replaced by liquid submerged culture. [ 1]

Edit this application.

At present, the traditional fermentation industry mainly adopts solid fermentation. For example, the production of soy sauce, from strain culture to koji making, and then to fermentation, adopts solid-state method. The fermentation conditions are relatively open, the process is simple, the equipment requirements are simple, and the cost is relatively low. Although some manufacturers have recently adopted submerged fermentation, it is obviously incomparable with solid fermentation in taste. For another example, in the production of vinegar, some manufacturers use liquid first and then solid, aiming at improving the flavor of vinegar.

Edit this section of original ecological solid fermentation.

Fungi are the most commonly used microorganisms in solid fermentation, because their hyphae can grow on the solid surface like the roots of plants and penetrate into the substrate to produce a variety of extracellular enzymes, which is more suitable for solid fermentation environment than other single-celled bacteria and yeasts.

Advantages of original ecological solid fermentation

1, solid substrates are usually macromolecular compounds, such as starch, cellulose, hemicellulose, pectin, lignin, protein and lipids. Fungi can often secrete such extracellular enzymes, and use the surrounding culture substrates as carbon sources (carbohydrates such as monosaccharides, disaccharides, oligosaccharides and polysaccharides) and nitrogen sources (such as bean cake powder, peanut cake powder, cottonseed cake powder, hydrolyzed plant protein and peptone). 2. The growth mode of mycelium is better than that of single cell, and the top of mycelium extends and branches to produce a new mycelium end, which can quickly cover the surface of solid substrate and effectively use the substrate; 3. If the hyphae are separated, substances can be transmitted through the pores of the diaphragm, and the pores will be automatically closed in case of danger to avoid the loss of cytoplasm; If there is no partition, the substances in the cytoplasm are quickly transferred, which makes the colonies multiply rapidly; 4. The growth of mycelium penetrates into the solid culture medium with strong force, forming high mechanical pressure, and it is easy to penetrate into the solid culture medium with the hydrolase secreted by the tip; 5, the selected substrate has low and controllable heavy metal and pesticide residues; 6. There are many kinds of active ingredients with high content.

Limitations of Original Ecological Solid Fermentation

1, long production cycle (120 ~270 days); 2. Large floor space, high labor intensity and high production cost. [2]

Edit this paragraph and compare it with liquid fermentation.

At present, the fermentation methods of enzyme preparation products are mainly solid fermentation and liquid fermentation, but some marketers and consumers have a lot of confusion and prejudice. Some people think that the enzyme products produced by liquid fermentation have high purity, less contamination by miscellaneous bacteria and good quality. Some people think that the products of solid fermentation have wide zymogram and good use effect. In fact, the two fermentation forms have their own advantages and disadvantages. First, let's understand what solid fermentation is. Solid fermentation refers to the biological reaction process carried out by one or more microorganisms in a water-insoluble solid substrate with no or almost no free water and a certain humidity. The raw materials used in solid fermentation are generally readily available and nutritious industrial and agricultural by-products and wastes, such as bran, potato powder, bean cake powder, sorghum and corn flour. Solid fermentation is a biological reaction process with gas phase as continuous phase. Solid fermentation is generally open, with simple equipment and easy operation. The general process is as follows: the raw materials are pretreated by cooking and sterilization. And then preparing solid materials with certain moisture, inoculating pre-cultured strains, and fermenting. After the fermentation is mature, timely discharge, proper treatment, or extract the product. High efficiency and simple and controllable extraction process. The disadvantages of this method are: high labor intensity and inconvenient mechanized operation. Liquid fermentation is a biological reaction process with liquid phase as continuous phase. The whole production process of liquid fermentation is easy to sterilize and automate. Liquid fermentation is more complicated than solid fermentation, and the investment in production equipment is large. Liquid fermentation includes aeration fermentation (submerged fermentation) and anaerobic fermentation According to different operation methods, it can be divided into batch fermentation, batch fed batch fermentation and continuous fermentation. I won't go into details here. It is worth mentioning that liquid fermentation originated from antibiotic fermentation and later developed into organic acid, amino acid and enzyme preparation fermentation. Antibiotics and organic acids can inhibit bacteria, so people feel that liquid fermentation is not easy to be polluted by miscellaneous bacteria, and the product quality is good. In fact, liquid fermentation must pay attention to every detail, including strict requirements for equipment and operation, otherwise it will be easily polluted by miscellaneous bacteria. For example, the fermentation product of enzyme preparation is enzyme protein, which not only can not inhibit miscellaneous bacteria like antibiotics, but also is a good nutrient for miscellaneous bacteria. Compared with solid fermentation, it is more threatened by miscellaneous bacteria pollution, and once it is polluted, the whole tank of materials is often scrapped, and the operation risk is greater. Both fermentation methods have their own advantages and disadvantages. Both fermentation methods can produce solid enzyme and liquid enzyme products. Solid fermentation can produce solid and liquid enzyme products, and so can liquid fermentation. The state of product is not necessarily related to which fermentation method is used. The key to the quality of enzyme products lies in the strict control of every detail and step in the production process, not in the difference of fermentation methods. In the application practice, Kangdian adopted the advanced production technology of solid-liquid combination, and completely integrated the advantages of these two fermentation methods to produce compound enzyme products with wide zymogram and multi-enzyme system. The enzyme preparation produced in this way has strong advantages in zymogram breadth and product purity, so as to better serve our feed industry, promote the overall improvement of the feed industry and create greater value for users. [3]

This product is suitable for liquid seed production and solid fermentation of biological products. Sterilization, cooling, inoculation and fermentation of materials are completed at the same station, which reduces the factors of bacterial pollution, has low energy consumption and no sewage discharge, and is the best biological fermentation equipment for solid materials. Main features: 1, floor-standing structure, personalized design, compact structure, high concentration and convenient use. 2. The design pressure of the tank is 0.3MPa, the short-term sterilization pressure is ≤0. 13 MPa, the working pressure during fermentation is about 0.05~0.07 MPa, the heat transfer of the jacket is controlled, and the inner and outer surfaces of the tank are polished, and the polishing accuracy Ra is ≤ 0.4. The tank and pipeline are disinfected in place, which is safe and reliable. 3. The equipment is equipped with several special standard interfaces for fermentors, such as temperature port, temperature control port and inoculation port. , to meet your detection and control of various fermentation parameters. 4. Adopt AC motor for mechanical stirring, stepless speed regulation, rotating speed: 50 ~ 120 rpm, adopt special mechanical seal for fermentation, adopt German technology, which is safe and reliable, and reduce the probability of leakage and bacterial pollution. 5. Screw belt agitator, which is used together with the draft tube to make the feed and liquid mix more evenly. 6. The air filtration system adopts advanced membrane filtration technology and two-stage double filtration. The accuracy can reach 0.0 1μm, and the rejection rate can reach 99.9999%, which greatly reduces the probability of bacterial contamination. 7. Stainless steel pipes and valves that meet the requirements of microbial fermentation should be used, and the surface should be polished. 8. Basic control parameters include: temperature, humidity, speed, pH value, pressure, etc. There are four control modes: a, b, c and d. See the automatic control section for details.