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Alcoholic fermentation process

I. Saccharification mash fermentation purpose requirements and equipment structure characteristics

(a) the purpose of the fermentation requirements

starchy raw materials after cooking, so that the starch is soluble, and after the role of trehalose saccharification enzyme, part of the generation of fermentable sugar, this is not the end of the production of alcohol in . Saccharification mash access to yeast; under the action of yeast, the sugar is transformed into alcohol and CO2, obtained alcohol products, which is the purpose of alcohol fermentation.

On the surface to observe the alcoholic fermentation, the process is very simple, it is just the saccharification mash into the fermenter after beating, access to the mother of wine, it can be fermented. However, in the process of alcoholic fermentation is a very complex biochemical changes occurring in the process: here both the starch and dextrin in the saccharification mash continue to be hydrolyzed by saccharification enzymes, generating sugar (i.e., post-saccharification), there are also proteins in the trehalose protease further hydrolysis of low molecular nitrogen-containing compounds, such as is cheong Cheong, peptone, peptide and amino acid role. These substances, some of which are absorbed and utilized by the yeast, synthesized yeast cells, the other part is fermented, generating alcohol and CO2 and other by-products.

Alcohol production, the requirement to use the least amount of raw materials to produce as much alcohol products, and should minimize fermentation losses, in order to achieve this purpose, it is necessary to create the following favorable conditions to achieve the purpose of the requirements:

(1) in the pre-fermentation period, to create the conditions for the yeast to continue to reproduce to a certain number.

(2) To allow the starch and dextrin in the saccharified mash to continue to be broken down to produce fermentable sugars.

(3) In the middle and late stages of the fermentation process, anaerobic conditions are created so that the yeast can ferment the sugars into alcohol under anaerobic conditions.

(4) The CO2 produced during the fermentation process should be excluded, and attention should be paid to strengthening the recovery of the capture of alcohol taken away when escaping with CO2.

(2) fermentation equipment

Alcoholic fermentation process is different, the fermentation equipment is also bribery differences. From the fermentation form, there are open, semi-closed and closed three. If from the material points, can be divided into two kinds of steel plate and cement.

Semi-closed fermentation tanks are made of steel plate, the top of the tank is equipped with a roof, the roof is equipped with a manhole that can be opened and closed.

The closed fermenter is also made of steel, steel plate thickness varies depending on the volume of the fermenter, generally 4 - 8 mm thick steel plate made of cylindrical tank body, tank body diameter and height ratio of 1:1.1; cover and bottom of the conical dish; tank cooling snake tube, snake tube number is generally taken for each cubic meter of fermentation mash with not less than 0.25 square meters of cooling area. The number of snake tubes is generally not less than 0.25 square meters per cubic meter of fermented mash. Snake tube can be divided into two groups of upper and lower installation, and be fixed. There are also used in the top of the tank with a shower pipe or shower enclosure so that the water along the wall of the tank to flow down, to achieve the purpose of cooling the fermentation mash. For the larger fermentation tank, these two cooling forms can be used at the same time. Alcohol plant located in the south, because of the high temperature, it should strengthen the cooling measures. Some factories set up bubble blowers at the bottom of the fermenter to stir the mash and make the fermentation uniform. The top of the tank is equipped with CO2 discharge pipe and heating steam pipe, mash input pipe. However, the piping setup should be simplified as much as possible, so that one pipe can be used for multiple purposes, which plays an important role in reducing the dead space of the pipe and preventing contamination by stray bacteria. The top and side of the large fermenter should also be equipped with manholes to facilitate cleaning.

Cement fermentation tank is made of reinforced cement, the shape can be divided into two kinds of round or square. Some made of sealed, can also be made of open type. Because the cement fermentation tank is easy to corrode, escape wine and sterilization is not complete and other shortcomings, so the general plant is not used.

V. Alcohol fermentation mash maturation

The control of alcohol fermentation mash maturation index is an important work in production. If the control is just right, not only can improve equipment utilization, increase alcohol production, and can greatly reduce raw material consumption, improve starch yield.

The maturation of the fermentation mash is related to factors such as fermentation time, mash concentration, fermentation temperature, yeast inoculum and fermentation method, but ultimately it is mainly controlled by several indicators listed in Table 1-45.

Section I Comprehensive Utilization of Wine Lees

Comprehensive Utilization

One, the utilization of starchy raw material lees

Two, the utilization of molasses lees

One, the utilization of starchy raw material lees

1. Wine feed lees lees is the fermentation of mature mash distillation of the waste liquid, the water content of the larger, at 90 - 98 ℃ % or so, dry matter content of 2 - 10% or so. For example, the composition of sweet potato dry raw material lees is 97.94% moisture, dry matter 2.06%.

The yield of lees is quite large, due to the use of raw materials and production methods vary. Generally for the alcohol production of 14 - 26 times, the actual production of 1 ton of 95 degrees of medicinal alcohol up to 26 tons of lees. This shows that the recycling of lees is very necessary and reasonable.

The dry matter composition of wine lees is mainly protein. Sweet potato dry raw material lees in the crude protein 0.34%, in the grain lees, soluble nitrogen content is about 15 - 20% of all nitrogen content. The remaining 80-85% is in a non-soluble state. In the dry matter of wine lees, besides protein, it also contains cellulose, polypropylene, ash, fat, caramel, melanin and other substances. The high nutritional value of wine lees as feed also lies in the fact that wine lees are rich in B vitamins and growth factors. Therefore, the rational utilization of wine lees should first be used as livestock feed. If the lees are made into dry lees and lees concentrate as the word material, it is of great significance to the development of livestock feeding industry because of the convenient transportation. In addition, wine lees contain trace ingredients such as riboflavin, thiamin, nicotinic acid, pantothenic acid, growth factor and choline, which are very similar to the composition of corn syrup. Therefore, some fermentation factories utilize lees concentrate instead of corn paddle, which is also one of the food saving measures.

2. Biogas fermentation Some alcohol factories in China utilize bacteria to carry out biogas fermentation on lees to produce biogas for fuel, which can save a lot of boiler coal for the country every year. For example, China's Henan Province, Nanyang You fine plant, the use of starchy raw material lees fermentation of biogas, a ton of lees can be fermented to produce 23 m cubic meters of biogas, 1 cubic meters of biogas combustion is equivalent to 0.8 kilograms of coal combustion of the calorific value. And the biogas fermentation equipment is relatively simple, the general alcohol plant is a large volume of lees fermentation tank for biogas fermentation.

The process conditions for biogas fermentation are as follows: the pH value of the lees should be adjusted to 7.8 - 8.9, and should not be lower than pH 7.8; the low-temperature fermentation temperature should be less than 38℃, the medium-temperature fermentation temperature should be 38 - 47℃, the high-temperature fermentation temperature should be 48 - 55℃, and the maximum temperature should not exceed 56℃. The maximum fermentation temperature should not exceed 56℃. The inoculation amount is 50% of the amount of lees, the fermentation will produce a large amount of biogas in 2-3 days, that is, it can be burned, the time of biogas fermentation is 4-5 days, the pressure in the biogas fermentation tank is 0.294 kPa. Normal fermentation biogas CO2 content of 40%, methane gas content of 60%, biogas fermentation process fermentation mash volatile acid content can not be more than 3000 ppm, the supernatant wave of biogas fermentation, but also the extraction of vitamin B12, the bottom of the dregs can be used as fertilizer, fertilizer efficiency is high. This makes the comprehensive utilization of lees further to make the best use of it.

3. Wine lees production of feed yeast The use of wine lees to produce protein-rich and cellulose-rich feed yeast, the development of China's mechanized feeding livestock industry has great significance. Wine lees according to its composition is a good raw material for the cultivation of feed yeast, the actual production of starchy original family lees cultivation of feed yeast, each cubic meter of lees can be 20-22 kg of absolute dry yeast, dry feed yeast with moisture 8-10%, protein content of 50-52%, rich in vitamin B. The production of feed yeast is a very important part of the development of China's mechanized feeding livestock industry.

Second, the use of molasses lees

1. Molasses lees extraction of glycerol Glycerol is an inevitable product of alcoholic fermentation, often present in the mash together with alcohol. Usually there is 0.5 - 0.6 grams of glycerol per 100 milliliters of mash, and when the mash is distilled, the glycerol remains in the lees after the alcohol is evaporated. Extraction of glycerol method is as follows: molasses lees should be concentrated to the dry matter content of about 95%, the concentration of lees jet to the vacuum distiller, with water vapor in the vacuum conditions of glycerol distillation, condensation and then distillation purification and concentration, that is, to get the finished product, this method can be extracted equivalent to the mash in the alcohol weight of 5 - 6% of the glycerol.

2. Molasses alcohol production of white mold White mold (Geotrichum Candidum) is an aerobic microorganisms, colonies of white fluffy, mycelium with a transverse septum, the liquid culture and to a certain extent split into a single or chain of cylindrical cells, which contains high protein, fat and vitamins, nutrient-rich. Some white mold strains, by the relevant units of verification, does not contain mycotoxins and other harmful substances, can use molasses lees culture, as livestock concentrate feed, is a better way of comprehensive utilization.

The use of molasses alcohol fermentation mature mash distillation of waste water, by precipitation to remove ash and other impurities, take the clear liquid diluted to the right degree, these waste liquid contains enough carbon, nitrogen, phosphorus and other nutrients to meet the growth of the white mold, but also because of the waste of lees water just out of the distillation tower, do not need to be sterilized again, can be used directly. Waste lees liquid cooled to the appropriate temperature, it will be expanded by ten times the amount of seed seed mother, control pH4.8 - 5.0, temperature 28 - 30 ℃, ventilation 1:1 (according to the amount of mash). Cultivate to mycelium large growth, can be harvested, and then filtered off the waste liquid, collect the bacteria, that is, for the water feed products.