KR102145851B1 - Method for Manufacturing Soft Tofu Containing Chitosan - Google Patents

Abstract

The present invention relates to a method for producing soft tofu in which chitosan is added during the production of soft tofu to increase the storage period of the soft tofu while preventing the added chitosan from lowering the texture of soft tofu.
The chitosan-containing soft tofu prepared by the method of the present invention increases the storage period of the soft tofu with the antibacterial function of chitosan, the useful ingredients of chitosan improve the nutritional function of the soft tofu, and the coarse texture of chitosan is reduced by the combination of chitosan and soy protein. It can show the original soft and smooth texture. In addition, since the soy milk that has been boiled and filtered is boiled again and coagulated after steaming, the texture of the soft tofu is soft and fragrant. The absorption of calcium contained in the soft tofu is high and the shape of the soft tofu is It doesn't get messy easily.

Description

Method for manufacturing soft tofu containing chitosan{Method for Manufacturing Soft Tofu Containing Chitosan}

The present invention relates to a method for producing a soft tofu in which chitosan is added during the production of soft tofu to increase the storage period of the soft tofu while preventing the added chitosan from lowering the texture of the soft tofu.

Sundubu is a high protein food with a light taste and soft texture, contains excellent nutritional ingredients and ingredients with high functional value, contains little saturated fatty acids, contains a large amount of unsaturated fatty acids, and does not contain cholesterol, so it controls dietary fat intake and adult diseases. It is a high-quality nutritional food that can reduce blood pressure.

Soybean, the raw material for soft tofu, is composed of approximately 40% protein, 35% carbohydrates, 20% lipids, and 5% other ingredients such as vitamins and minerals. It consists of essential amino acids.

In particular, soybeans contain physiologically active substances such as isoflavone, saponin, lecithin, peptides, amino acids, etc., so it is known to be effective in preventing aging of the brain, preventing adult diseases, recovering liver function, preventing thrombosis, preventing and treating various heart diseases and cancers. have.

Soft tofu is usually weakly acidic at a pH of 5.2 to 6.2, but when consumed, it acts as an alkaline food in the body to improve the acidic constitution of the human body, and when eating meat to consume protein, there is a risk of complications due to cholesterol increase. It is highly recommended to patients, and despite its excellent digestion and absorption rate, it is in the spotlight as a diet food due to its low caloric content.

Sundubu is a food in which the pressing process is omitted in the manufacturing process of tofu. It is prepared by soaking soybeans in water, separating the crushed soybean water from bean curds and soymilk, boiling the separated soymilk, adding a coagulant and coagulating it.

However, since these soft tofu are rich in moisture and nutrients, there is a possibility that the physiologically active substances contained in soft tofu may deteriorate during storage. In particular, sugar or aglycone produced by the decomposition of glycosides by beta-glucosidase is nearby. It acts as a nutrient source for spoilage bacteria present in the tofu, which has the disadvantage of easily decaying soft tofu.

In order to increase the storage properties of soft tofu, the soft tofu is sterilized at high temperatures or by adding anti-corruption enzymes or preservatives to extend the storage period. However, high-temperature sterilization destroys not only spoilage bacteria but also the nutrients contained in the soft tofu, and additives There is a risk of deteriorating taste and unhealthy.

In addition, sundubu is rich in high-quality protein, but phytic acid inhibits absorption of minerals in the intestine, resulting in uneven nutrition when consumed in large amounts.

In order to solve this problem, a method of adding natural ingredients that can increase the storage properties of soft tofu and improve nutritional functionality is being developed. Among these methods, chitosan having antibacterial activity is added to the manufacturing process of soft tofu. Is presented.

For example, Korean Laid-Open Patent Publication No. 2000-0051125 proposes soft tofu containing chitosan and chitosan oligosaccharides, and natural coagulants, chitosan and chitosan oligosaccharides, seaweeds, mudfish, shellfish, greens, wild grasses, seasonings, etc. Sundubu was prepared by adding and coagulating it. The purpose was to prevent shortage of minerals in the human body by inhibiting absorption of phytic acid by containing minerals in the sundubu while preventing the sundubu from easily decaying by the antibacterial action of chitosan.

However, as described above, when several subsidiary materials are mixed in the soft tofu, the original clean and light taste of the soft tofu disappears, and seaweed, shellfish, and vegetables are mixed with oligosaccharides, which in turn promotes spoilage.

Thus, in Korean Patent Publication No.0862045, soybean milk is obtained by mixing boiling water with soybeans that have been crushed and strained, and filtering again to obtain soymilk.The soybean milk is boiled and deep sea water with chitosan added thereto is added as bittern, coagulated and compressed to tofu. A method of making it has been presented.

In the present invention, deep sea water containing a large amount of minerals and chitosan having an antibacterial function are added to the tofu to solve the problem of mineral shortage and decay in the tofu, and to manufacture functional tofu having excellent strength and elasticity.

However, since chitosan originally has a rough texture, the tofu prepared as described above has a rough texture, and when the soft tofu is manufactured by omitting the pressing process in the manufacturing process, there is a disadvantage that the smooth and soft appearance and texture of the soft tofu are impaired.

The present invention is to solve the above problem, and while adding chitosan during the production process of soft tofu in order to increase the storage period of soft tofu, a method for producing soft tofu that can prevent the texture of soft tofu from becoming sloppy due to the addition of chitosan Is to provide.

In order to solve the above problems, the present invention comprises the steps of preparing soybean water by grinding beans after soaking them in water; Preparing a water-soluble hydrogel chitosan by mixing 100 to 150 parts by weight of anhydrous acid to 100 parts by weight of chitosan and reacting for 10 to 20 minutes at a temperature of 30 to 50°C; Boiling 100 parts by weight of the soybean water and then adding 0.1 to 5.0 parts by weight of the water-soluble hydrogel chitosan; Filtering the soybean water to which the water-soluble hydrogel chitosan has been added with a cloth while stirring, and stirring the soybean milk while scratching the cloth while pouring hot water into the soybean water during the filtration to obtain soymilk from which the soybean milk has been removed; And stopping the heating after boiling the soymilk again, allowing it to stand for 10 to 15 minutes with a lid on it, and then adding a coagulant to coagulate it. It provides a method for preparing soft tofu containing chitosan.

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At this time, it is preferable that the coagulant is deep ocean water.

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Since the chitosan-containing soft tofu prepared by the method of the present invention increases the storage period of the soft tofu with the antibacterial function of chitosan, the useful ingredients of chitosan improve the nutritional function of the soft tofu, and the coarse texture of chitosan is reduced by the combination of chitosan and soy protein. It can show the original soft and smooth texture of soft tofu.

In addition, since the boiled and filtered soymilk is boiled again and coagulated after steaming, the soft tofu texture is soft and fragrant, and the calcium contained in the soft tofu is highly absorbed by the human body and the shape of the soft tofu is not easily disturbed by external force.

In general, sundubu is prepared by pulverizing soybeans such as soybeans or seoritae by sufficiently pulverizing it, filtering the soybean milk to remove the soybean milk, and boiling the soybean milk, adding a coagulant, and coagulating.

Since such soft tofu is rich in moisture and nutrients and is susceptible to decay, in the present invention, chitosan, which has an antibacterial function, is added during the production of soft tofu to increase the storage properties of soft tofu, and the soft and smooth texture of soft tofu is not inhibited by the added chitosan. .

First, the soybean is soaked in water and soaked, and the soybean water is prepared by grinding it with water, and then it is boiled and filtered with a cloth, and chitosan is added when the soybean-water is filtered.

Chitosan is a water-insoluble high molecular substance in which the N-acetyl group is substituted with an amino group by deacetylating chitin contained in crustaceans such as shrimp, crab, insect shells, and squid bones. It is composed of glucosamine bonds and has a molecular structure in human tissues. It is very similar to that, so it has excellent human affinity and does not cause an immune rejection reaction, so it is known as a very useful material as a food or medicine.

Chitosan is a cationic natural polymer that is abundantly present after cellulose in nature, and the molecular structure of chitosan is very similar to that of cellulose, but has various physicochemical properties due to the presence of amino groups (-NH ₂ ) in the molecule, antibacterial and antifungal It has effects such as sex, adsorption of heavy metals, physiological activity, human affinity, promoting wound healing, lowering cholesterol, improving liver function, and lowering blood sugar.

In the present invention, chitosan having the above effects is added to the soft tofu to increase the storage properties and improve the functionality of the soft tofu. Chitosan does not dissolve in water and exhibits a chewy texture when ingested, thereby inhibiting the soft and smooth texture of the soft tofu.

However, when chitosan is added to soybean water boiled as in the present invention, chitosan is combined with soy protein, and chitosan combined with soy protein decreases the coarse texture.After adding chitosan to soybean water, filtering with a cloth results in the combined soy protein-chitosan Since the large particles are filtered through the cloth, the coarse texture of chitosan is further reduced and the original soft and smooth texture of the soft tofu can be expressed.

To explain this in more detail, glycinin-soluble protein, which accounts for most of soybean protein, is dissolved in soybean water and is negatively charged. Chitosan, unlike cellulose, has an amino group, which is a cation, so it is positively charged. Therefore, when chitosan is added to soybean water, glycinin of negatively charged soy protein and (+) charged chitosan are combined.

At this time, while chitosan neutralizes the negative charge of the soybeans, the soy protein that was suspended in a colloidal state is coagulated to generate gel-like soft tofu particles, and the soft tofu particles are filtered by the cloth and may not pass through the cloth. , It is preferable to pass the soybean water through the fabric and at the same time add chitosan to allow the chitosan-added soybean water to pass through the fabric while glycinin and chitosan in the soy protein are bound, but the soft tofu particles are not yet produced.

Stir continuously with a spatula to ensure that chitosan is evenly mixed with the soybean water contained in the fabric.Before passing through the fabric, soft tofu particles may be generated, so when stirring the soybean water, scrape the fabric while stirring so that the soft tofu particles pass through the fabric easily. By making it possible to do so, it suppresses the decrease in the manufacturing yield of the net pier.

The amount of chitosan added is preferably 0.1 to 5.0 parts by weight based on 100 parts by weight of soybean water, but the present invention is not limited thereto, and since the soybean water is filtered with a cloth, the bean water contained in the soybean water is naturally removed to obtain soy milk containing chitosan.

As the soybean milk flows through the cloth, the solid bean-fat component increases on the cloth. Therefore, even if the cloth is stirred while being scraped, the more the filtration proceeds, the more difficult it is for the soy protein-chitosan particles to pass through the cloth.

Therefore, keeping the density of the solids in the soybean water below a certain level by intermittently pouring hot water, preferably boiling water, into the soybean water during filtration allows the soy protein-chitosan particles to pass smoothly through the fabric. desirable.

Since chitosan is not soluble in water, there is a concern that it may not be sufficiently combined with soy protein. In order to overcome this disadvantage, chitosan can be mixed with vinegar and then added to the soybean water.

Since chitosan has a property of dissolving in the acidic region, it is dissolved in vinegar and can be easily combined with soy protein.It is preferable to use an aqueous vinegar solution having an acetic acid concentration of 3 to 7% by weight so that the acidity of the vinegar does not impair the flavor of the soft tofu. And it is more preferable to mix 80 to 120 parts by weight of the aqueous vinegar solution to 100 parts by weight of chitosan.

In addition, soft tofu contains a lot of calcium, but calcium is easily insoluble in the body, so its absorption rate is low. Calcium combines with sodium hydrogen carbonate in the digestive juice secreted from the pancreas and is insoluble calcium carbonate. Calcium carbonate, which produces calcium carbonate) and is insoluble in water, is not absorbed by the body and is excreted outside the body.

In order for calcium to be absorbed in the body, it must be dissolved in water. The acetic acid component of the vinegar is combined with calcium and converted to calcium acetate, and calcium acetate is dissolved in water and absorbed in the intestine. Can increase.

As another method of dissolving chitosan in water to sufficiently bind soy protein, chitosan may be modified into a water-soluble hydrogel and then added to soybean water.

Chitosan is not soluble in water due to strong hydrogen bonds and high crystallinity between molecules, so by appropriate modification of the terminal functional groups of chitosan molecular chains, the hydrogen bonding power is lowered and inter-molecular space is secured, so that water-insoluble chitosan has water-soluble properties.

To this end, some amino group hydrogens in the chitosan molecular chain are substituted to ensure water solubility, and hydrogen substitution can be performed using N-acylation reaction, and the N-acylation reaction is performed by addition between chitosan and acid anhydride. ㆍCan be achieved by substitution reaction.

100 to 150 parts by weight of anhydrous acid is mixed with 100 parts by weight of chitosan and reacted for 10 to 20 minutes at a temperature of 30 to 50°C to prepare a water-soluble hydrogel chitosan. The amino group hydrogen of chitosan is reacted for a short time at a low temperature as described above. Only some of them participate in the N-acylation reaction and are substituted. Therefore, the prepared hydrogel chitosan has water solubility through a partial N-acylation reaction, and the remaining amino groups that do not participate in the reaction are bound to the soy protein.

If the anhydrous acid is less than 100 parts by weight, the N-acylation reaction is not sufficient and the ratio of conversion of insoluble chitosan into a water-soluble hydrogel is low.If it exceeds 150 parts by weight, gelation proceeds too much and the viscosity is high, so that it cannot be evenly dispersed in the bean water. In addition, the substitution rate of amino group hydrogen is too high, so there is a concern that the binding with soy protein may become insufficient.

As the anhydride, acetic anhydride, succinic anhydride, methyl succinic anhydride, diglycolic anhydride, maleic anhydride, itaconic anhydride ) Or citraconic anhydride (citraconic anhydride) may be used.

The water-soluble hydrogel chitosan modified as described above can maintain the original efficacy of chitosan since the high molecular chitosan does not become low molecular weight, so it can improve the storage properties of soft tofu and fully impart the beneficial effects of chitosan to the soft tofu, and hydrogel chitosan The viscosity of the soft tofu collects the soft tofu particles generated in the post-process, so the aggregated form of soft tofu does not become easily disturbed during the handling of soft tofu products.

When chitosan is added to the soybean water and filtered as described above, soybean milk is removed and chitosan-added soymilk is obtained.In the present invention, the soybean milk is boiled again and then a coagulant is added to coagulate the soybean protein to prepare sundubu. A coagulant may be added without boiling again, but in this case, the temperature of the soymilk is low, so that the soft tofu is not sufficiently produced, or the produced soft tofu particles do not clump together, and the water including the soft tofu may become cloudy.

That is, the coagulation of soy protein is a process in which the pH of the soy protein solution is denatured by heat at the isoelectric point.If chitosan is added to the soybean water and filtered with a cloth while stirring, as in the present invention, it takes time for the soy protein-chitosan particles to pass through the cloth. It takes a lot and the temperature of the soybean milk decreases as the soybean water is stirred. Therefore, even if the pH is adjusted to the isoelectric point by adding a coagulant to the soymilk, the thermal denaturation of the protein cannot proceed smoothly due to the low temperature, and the production of soft tofu is insufficient. Boil the soymilk again as above and add a coagulant.

In addition, it is preferable to steam the boiled soymilk before adding the coagulant, and then add the coagulant.If the coagulant is added at the boiling temperature of the soymilk, the fragrant odor of the soft tofu is weakened, the surface of the soft tofu is not smooth, and holes like gombo are created. It is not desirable in appearance.

For the steaming, it is preferable to stop heating the boiling soymilk and allow it to stand for 10 to 15 minutes with the lid of the container covered, and the soymilk after the standing time is sufficiently heat-denatured so that no holes are formed on the surface of the soft tofu. Cool down to an appropriate temperature.

In addition, as the coagulant, an electrolyte such as chloride such as magnesium chloride (MgCl ₂ ) or calcium chloride (CaCl ₂ ) or sulfate such as calcium sulfate (CaSO ₄ ) may be used, but it is preferable to use seawater as a coagulant and a depth of 200 m It is more preferable to use deep ocean water collected above.

Since sunlight does not reach deep ocean water, there is no phytoplankton that consumes nutrients, and photosynthesis does not occur, so it is rich in inorganic nutrients. It is stagnant in the deep sea for a long time, so various minerals such as magnesium, calcium, potassium, sodium, and zinc, selenium and manganese A large amount of trace elements such as etc. are present in a stable form.

In addition, it is known to have excellent cleanliness compared to surface water or groundwater because there is no pollution by air or influent water and no general bacteria are contaminated, and it is known to have an excellent scavenging effect for active oxygen due to the action of dissolved metal ions.

Therefore, if the deep sea water is used instead of the synthetic coagulant, the liver of the soft tofu is properly controlled, and the high mineral content of the deep sea water increases the mineral content insufficient in the soft tofu, and the soft texture of the soft tofu can be further improved.

Hereinafter, the present invention will be described in more detail based on the following Examples, Comparative Examples and Test Examples.

However, the following examples are only for illustrating the present invention, and the present invention is not limited by the following examples, and can be substituted and equivalent to other examples within the scope not departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in the art to which the present invention pertains.

<Example 1>

1 kg of soybeans were soaked in water for 12 hours and removed, then 3 kg of drinking water was added thereto, followed by grinding to prepare bean water. The bean water was put in a heating container and boiled sufficiently.

The boiled bean water was poured into the cloth, and then 100 g of chitosan powder was mixed thereto, and then stirred continuously while scraping the cloth with a spatula.

While stirring, boiled drinking water was supplemented little by little in proportion to the amount of soymilk passing through the weeping machine. After all the soybean water was filtered, the soymilk contained in the container was put into a heating container and heated again.

When the soymilk boiled, the heating was stopped and the lid was kept covered. After 12 minutes, 100 g of deep sea water was added and mixed evenly to prepare sundubu.

<Example 2>

In Example 1, except that the chitosan powder was dissolved in 100 g of an aqueous vinegar solution having an acetic acid concentration of 5% by weight and mixed with soybean water, sundubu was prepared in the same manner as in Example 1.

<Example 3>

In Example 1, 100 g of chitosan powder was mixed with 120 g of acetic anhydride, reacted for 15 minutes at a temperature of 40° C., and then mixed with soybean water to prepare sundubu in the same manner as in Example 1.

<Comparative Example 1>

In Example 1, sundubu was prepared in the same manner as in Example 1, except that chitosan powder was not mixed with soybean water but mixed with soy milk with deep ocean water.

<Comparative Example 2>

In Example 1, sundubu was prepared in the same manner as in Example 1, except that deep sea water was added immediately without boiling the soymilk passed through the weeping machine again.

<Test Example 1> Analysis of changes in the number of bacteria during storage

Using commercially available soft tofu without chitosan added (2 days after production) as a control, and keeping the soft tofu prepared in Examples 1 to 3 and Comparative Examples 1 and 2 in a refrigerator, the number of bacteria and E. coli during storage The change of was analyzed.

The number of bacteria was analyzed according to the microbial test method of the Food Code. For each soft tofu in each group, after sufficiently mixing the soft tofu with a sterilized glass rod, take 20 ml, put it in a sterilization container, and mix 9 times of sterile physiological saline as a sample. I did.

1 ml of the soft tofu sample was aseptically taken on a standard agar medium, dispensed, and incubated for 36 hours in an incubator at 35°C, and the number of colonies generated was measured. As a result of the measurement, E. coli was not detected. And the results were averaged and shown in Table 1 below.

Analysis result of change in the number of general bacteria by storage period (unit: cfu/ml) Immediately after manufacture 10 days elapsed 20 days elapsed 30 days elapsed Example 1 5.5×10 3.5×10 ² 1.7×10 ³ 2.6×10 ⁵ Example 2 5.2×10 3.1×10 ² 1.4×10 ³ 2.2×10 ⁵ Example 3 5.3×10 2.7×10 ² 1.2×10 ³ 1.7×10 ⁵ Comparative Example 1 5.5×10 5.3×10 ² 2.1×10 ³ 4.3×10 ⁵ Comparative Example 2 5.2×10 3.3×10 ² 1.6×10 ³ 2.4×10 ⁵ Control 1.8×10 ² 5.7×10 ³ 8.4×10 ⁵ 5.5×10 ⁸

As shown in Table 1 above, the soft tofu of the control group showed the highest number of normal bacteria since the analysis value immediately after production was 2 days after production, and as the storage period increased, the growth of bacteria increased, and the examples containing chitosan The and Comparative Example did not show a significant difference until the lapse of 20 days, and after 30 days, the number of common bacteria of Comparative Example 1 in which chitosan powder was mixed with deep sea water and soy milk increased slightly, but there was no significant difference between them.

Therefore, if chitosan is added during the production of soft tofu, it is believed that the safety of soft tofu will be secured by inhibiting the reproduction of microorganisms during distribution due to the antibacterial ability of chitosan.

<Test Example 2> Sensory test

The appearance, color, taste, aroma, and overall acceptability of the soft tofu of Examples and Comparative Examples and the control soft tofu of Test Example 1 were measured in a 5-point scale, targeting all 70 men and women from their teens to their 70s. The average values are shown in Table 2 below.

Sensory test result Exterior color flavor incense Overall preference Example 1 3.9 4.0 3.8 3.7 3.8 Example 2 4.0 3.9 4.0 3.6 3.8 Example 3 4.1 4.0 4.0 3.7 4.0 Comparative Example 1 3.9 3.7 3.6 3.7 3.7 Comparative Example 2 3.5 3.8 3.5 3.4 3.6 Control 4.0 4.1 3.5 3.3 3.5 5: very good, 4: good, 3: moderate, 2: bad, 1: very bad

As shown in Table 2, the soft tofu of the Example received a similar evaluation as a whole, but looking at the Comparative Example, Comparative Example 1 in the evaluation of color and taste, Comparative Example 2 in the appearance, taste and aroma, and the control group in taste and aroma. I got a low score.

In the case of Comparative Example 1, in which chitosan powder was mixed with soybean water and then mixed with soymilk with deep sea water without filtering with a weaving cloth, the white of the soft tofu was slightly faded, and the texture of the soft tofu was felt. Comparative Example 2, which was coagulated immediately without boiling again, was evaluated that the surface of the soft tofu was not smooth, the water of the soft tofu was slightly cloudy, the softness when chewing was less, and the savory flavor was weak compared to other groups.

Therefore, when chitosan is added to increase the shelf life of soft tofu, it can be seen that the appearance and flavor of the soft tofu should be improved by mixing chitosan powder in the soybean water after grinding soybeans as in the Example, filtering it with a weaver, and boiling it again to solidify it. .

In the overall acceptability, the examples were evaluated higher than those of the comparative examples, so that the commerciality of the soft tofu according to the present invention could be confirmed.

Claims (7)

Soaking the beans in water and grinding them to prepare bean water;
Preparing a water-soluble hydrogel chitosan by mixing 100 to 150 parts by weight of anhydrous acid to 100 parts by weight of chitosan and reacting for 10 to 20 minutes at a temperature of 30 to 50°C;
Boiling 100 parts by weight of the soybean water and then adding 0.1 to 5.0 parts by weight of the water-soluble hydrogel chitosan;
Filtering the soybean water to which the water-soluble hydrogel chitosan has been added with a cloth while stirring, and stirring the soybean milk while scratching the cloth while pouring hot water into the soybean water during the filtration to obtain soymilk from which the soybean milk has been removed; And
After boiling the soymilk again, stopping heating, allowing it to stand for 10 to 15 minutes with a lid on it, and then adding a coagulant to coagulate it. delete delete delete delete The method according to claim 1,
The method for producing soft tofu containing chitosan, wherein the coagulant is deep ocean water. delete