Raw materials

The raw materials used in the soy sauce production process are mainly soybean meal and wheat.

I. Advantages of soybean meal as raw material
1. Can maintain the flavor of soy sauce made from soybeans
2. High protein content, low raw material costs.
3. Raw materials do not have to be crushed and processed, can be directly used to run water cooking.
4. Saving oil and grease

Second, the advantages of wheat as raw materials
1. The use of starch raw materials, soy sauce concentration, pigment, flavor, sweetness of the main ingredients.
2. Containing wheat gluten, decomposition of glutamic acid, is the main source of soy sauce flavor.
3. Contains lignin, which produces 4-ethyl guaiacol, one of the important components of soy sauce flavor.
d. Wheat bran, containing protein and polypentose, combined with amino acids in soy sauce can produce dark brown pigment, increasing the color of soy sauce.

Raw material processing

I. Soybean meal
(A) processing methods
1. First put the soybean meal into the pot, open the rotating pot, while the steam dry steaming to 110 ℃, turn off the steam, remove the residual steam, so that the pot pressure down to 0.
2. Pumped into the weight of soybean meal 1-1.1 part of the water, rotary cooking pot wetting 20min.
3. Open steam temperature rises to 80 ℃, close the steam, exclude the cold air in the pot, continue to open the steam temperature to 110 ℃ to maintain 20min, off the steam pressure to 0. Cooking pot de-pressurization immediately after the lid out of the material.

(ii) Identification
1. Cooked material requires a pale yellow color, slightly darker than before cooking.
2. Loose texture, feel elastic, high water but do not feel wet, pinch the non-sticky hands.
3. Fragrance, no hard heart, no bad smell.
4. The moisture of the cooked material meets the requirements, and the digestibility reaches more than 80%.

II. Wheat
(I) processing method
1. Turn on the wheat frying machine, ignite the liquefied steam, when the temperature rises to 335 ℃ or so, began to enter the wheat.
2. The fried wheat is cooled by a conveyor belt, crushed and pneumatically transported to the wheat flour silo.

(ii) Identification
1. The appearance of the cooked material should be golden yellow.
2. Scorched lake particles not more than 5%-20%, cooked wheat for water throwing experiment should be ≤ 3% sinking rate.

Cooking

I. The technical key of song making
1. Choose fresh and good seed song.
2. Raw material wetting should be appropriate, the moisture of cooked material is not less than 46%, not higher than 50%.
3. Raw material cooking protein denaturation should be moderate, excessive denaturation will make the clinker sticky and produce factors that hinder the growth of Aspergillus oryzae.
4. Any contact with the clinker tools, equipment, transportation facilities and the environment, etc., must be clean and sanitary, in order to prevent contamination of fungi.
5. Inoculation should be uniform, pay attention to the kind of song and clinker flow uniformity, in order to prevent the phenomenon of seed breakage.
6. Temperature management (pre-temperature of 29-30 ℃, the middle should pay attention to temperature control and heat dissipation, late to master the low temperature 26-28 ℃, low-temperature quaking is conducive to the improvement of enzyme activity).
7. Quaking management (due to the thick layer of material, the layer of material at various points in the temperature gap, pay attention to the curve before, after and on, in, under the temperature changes, the requirement to narrow the temperature gap, to keep the curve loose, turn the curve in a timely manner to prevent the curve from slating and cracking to run the wind).
8. Every time the quaking is finished, pay attention to the cleaning and sanitary work of the quaking room, quaking pool and conveying pipeline and tools.

Second, the common problems in the production of song and its diagnostic methods
(A) flower song, acid song, stink song
1. Flowering
(1) Phenomenon: When the clinker inoculation is not uniform, a layer of raw materials without discoloration will appear in the place where it is not received by Aspergillus oryzae; and there will be a local high temperature burnt curve in the place where there is too much inoculation of currant materials.
(2) Diagnosis: Require uniform inoculation, prudent management, observation of plane currant each point of the product temperature.

2. Sour Qu
(1) Sour Curve: contaminated with a large number of acid-producing cocci and fecal streptococci.
(2) Diagnosis: equipment, tools, pipes, etc. should be cleaned to keep clean; raw materials should not be too high in water; at the same time, pay attention to temperature management, product temperature should not be lower than 25 ℃.

3. Stinky Qu
(1) stink song: contaminated Bacillus subtilis, consume the protein and starch in the raw material, and produce ammonia, the song is sticky, odor, stimulate the nose and eyes.
(2) Diagnosis: the temperature of the cultivated product should be controlled below 38℃; after contamination, the equipment and the curved room should be thoroughly cleaned and the sterilization work should be done carefully.

(B) Qu material without acid and odor without discoloration (mostly seen in the yellow plum season)
1. Phenomenon: If the raw material is high in moisture, in the pre-inoculation of low temperature, the curve material for a long time does not produce heat, even though many times ventilation and heating, but also not very effective, cultivation after 24h is still the color of the clinker. Most of this kind of currant is contaminated with mold-producing yeast, which does not produce alcohol and consumes starch in the raw material.
2. Diagnosis: the process of quaking should be well controlled to create growth conditions for Aspergillus oryzae. (Competitive growth)

(C) into the song grows well, but the enzyme activity is not high
1. Low moisture of clinker (below 44%).
2. High temperature in the middle and late stages of the production of quartz. Low temperature conditions are favorable for the generation of hydrolytic enzymes such as protease and amylase, and glutaminase, peptidase and other enzymes need to be generated under low temperature conditions.

(D) into the song lump hard into the song loose like sand
1. Quartz agglomeration hard
If the moisture of the clinker is large, turn the curve too early (mycelium just grows, turn the curve is too tender), then into the curved mycelium thick, curved hard. Because of the late quilting material contraction and cracks, breaking the wind, must be shoveled, or the third turning material to solve the problem of wind. Mycelium is white, hard texture, fewer spores.

2. Loose as sand
If the moisture of the clinker is low, and the turning of the song is too late (mycelium growth is white, and the turning of the song is too old), the song will be hard and difficult to crack, and it will not be easy to lump again after the turning of the song. And low moisture, mycelium no longer reproduce. Even for the second time to turn the song, the song-making late also loose as sand, not block, mycelium sparse, spores slightly fluttering. This kind of enzyme activity will not be very high. The reason is that the water loss is too fast.

Third, the identification of the quality of the song
(A) the quality requirements of the sensory identification of the quill
1. The material is loose and soft with elasticity; the appearance is lumpy, but loose without hard center; the mycelium inside the layer is full and thick, and densely bearing young yellow spores, no color, no center.
2. It has normal flavor, no ammonia, acid and other odors.

(II) Physical and chemical indexes
1. Moisture requirement
32-35% for 1 day, 26-30% for 2 day.
2. Protease activity
Neutral protease activity is more than 1000u/g (dry basis).
The total number of bacteria in the finished song is less than ^5×109/g.

The types of contaminated bacteria and prevention

First, the microbial species often contaminated in the production of music
(A) mold
1. Trichoderma mycelium is white, like rabbit hair, easy to grow in low temperature, high humidity conditions. A small amount of pollution has little effect, a large amount of pollution will hinder the growth of Aspergillus oryzae.
2. Root mold mycelium is white, like a spider web. In high humidity conditions easy to reproduce, there is a certain glycolytic enzyme activity. A small amount of pollution has little effect.
3. Penicillium mycelium is gray-green, spores into green. Easy to grow at low temperatures. Can produce moldy smell, affecting the flavor of soy sauce.

(ii) Yeast
1. Beech’s yeast can produce mold, consume the sugar in soy sauce, can not produce alcohol.
2. Mold yeast Forms mold on the surface of soy sauce, which can decompose the ingredients in soy sauce and reduce the flavor. It is a harmful yeast commonly found in soy sauce production, and grows white flowers on the surface of soy sauce. This kind of yeast is easy to grow under low temperature and high humidity ventilation. It is very easy to contaminate this bacteria during the rainy season in the south of the Yangtze River.

(iii) Bacteria
1. Micrococcus is the main bacteria contaminated by song making. In low temperature, high humidity and ventilation conditions are very easy to grow, often in the early stages of breeding. Can produce weak acid, so that the PH of raw materials slightly decreased; if a large number of contamination will affect the growth of Aspergillus oryzae, consumption of raw materials and nutrition; its bacterial body in the soy sauce will cause turbidity in the soy sauce.
2. Streptococcus faecalis is very easy to grow under the conditions of high temperature, high humidity and poor ventilation in the pre-cooking period.
3. Bacillus subtilis is a representative of the harmful bacteria of the song-making pollution. In high temperature (37-40 ℃) under high humidity conditions reproduction is very fast. It can consume starch and protein in raw materials, produce pungent ammonia odor, make the quartz sticky, and the naked eye can see the water droplets appearing in the material, with a peculiar smell, and feel sticky.

Prevention and control methods
1. To master the appropriate moisture of the material. And raw material moisturization is the primary technical key.
2. Cultivate in ventilated conditions, to avoid the air environment, tools and equipment pollution. Must pay attention to contact with clinker conveying equipment, winch pipeline, tools, curved pool, etc., after each day’s work to brush clean. Sterilization is carried out when necessary to reduce the pollution of the environment and equipment.
3. Strengthening the management of the process of making music
1) Inoculate evenly, and pay attention to the inoculation temperature and the pool temperature.
(2) To maintain the appropriate temperature at the beginning of the quaking process, and strengthen the management of temperature and humidity during the whole quaking process; pay attention to the ventilation regulation, and master the key points of the quaking process. Select the conditions suitable for the growth of Aspergillus oryzae in management to protect it from competition.

Fermentation management

First, into the pool management
Due to the hardness of the quartz, there are a large number of spores, so it can not quickly absorb the brine and float in the liquid surface, the formation of the mash cover; and because of the low salt concentration inside the quartz block, the original bacteria in the quartz and non-salt-resistant lactobacilli are easy to reproduce, heat, and produce the stench of corruption, the smell of drums and ammonia, so that the PH drops excessively to reduce enzyme vitality. Therefore, it should be mashed in time.

Second, turn the sauce management
Turning sauce through compressed air, turning sauce time should be short. If the time is too long, the mash is fine and sticky, which not only affects the alcoholic fermentation, but also hinders the mash maturation and pressing.

In the early 10 days of fermentation, turning the sauce should be more often, so that the brine soaked into the song. After that, turn the sauce every 4-5 days. When the yeast alcohol fermentation is strong, the sauce can be turned once every 3 days. After the main fermentation, you only need to turn the sauce 1-2 times a month. In the 6-month fermentation process, a total of about 20 times to turn the sauce.

Temperature management
Usually, making and fermenting in winter with lower temperature can be favorable for the formation and action of neutral protease and glutaminase of the song. In the first month after the material into the pool, sauce mash temperature control for 15 ℃.

Fermentation at this low temperature inhibits the growth of lactic acid bacteria and keeps the pH of the sauce mash at about 7. Later, the product temperature gradually rises, lactic acid, fermentation, salt-resistant lactic acid bacteria or salt-loving sliced ball bacteria can proliferate to 108/ml. when the PH drops to 5.0-5.5, the product temperature rises to 30 ℃, is the most vigorous period of alcohol fermentation. Add pure culture of good strain culture liquid to the mash, and after 2 months of fermentation, the PH drops to below 5.

At this time, protein decomposition and alcoholic fermentation have basically ended, and alcohol can be generated 2%-3%. The following 4 months, should continue to maintain the product temperature of 28-30 ℃, by the ball of yeast to participate in the maturation, the generation of 4-ethyl guaiacol and other aroma components, so that the mash gradually formed the color and complex mellow flavor, the mash is gradually mature.