CN116369467A - Bean curd preparation process and bean curd - Google Patents

Abstract

The invention belongs to the technical field of food processing, and discloses a preparation process of bean curd and the bean curd. The preparation process of the bean curd comprises the following steps: s1, preparing soybean milk, wherein the soybean milk is prepared by taking beans as raw materials; s2, preparing a modified liquid, and adding curdlan, modified starch, white granulated sugar and glucolactone into water to obtain the modified liquid; s3, adding the modified liquid into the soybean milk at the first temperature to obtain a process product; s4, heating the process product to a second temperature, preserving heat for a first time, and cooling to obtain the soft bean curd. Under the combined action of curdlan, modified starch, white granulated sugar, glucolactone and soybean milk, the cross section of the frozen soft bean curd after thawing is free of holes, so that the frozen soft bean curd keeps the tender and smooth taste before thawing, the soybean milk is prepared from bean raw materials, the bean flavor is aromatic, and the white granulated sugar has the effect of relieving the sour taste of the frozen soft bean curd, so that the bean flavor of the frozen soft bean curd is highlighted.

Description

Bean curd preparation process and bean curd

Technical Field

The invention relates to the technical field of food processing, in particular to a preparation process of bean curd and the bean curd.

Background

The bean curd is a main raw material of vegetarian dishes in China, the traditional soft bean curd has high moisture content and short shelf life at normal temperature, and at low temperature, spongy or layered structures such as frozen bean curd can be formed due to protein denaturation, so that the tender and smooth mouthfeel of the soft bean curd is damaged, and the soft bean curd is not required.

In the prior art, in order to improve the frozen taste of the bean curd, starch and transglutaminase are added into the soybean milk, so that the freezing resistance of the prepared bean curd is improved to a certain extent, but the viscosity of the soybean milk is high, and the coagulation reaction is difficult to control. Furthermore, the freezing resistance of the bean curd is further improved by concentrating the solid content of the raw soybean milk to 10-16% on the premise of not changing the concentration of the soybean milk. However, the process requirement for concentrating the soybean milk is high, so that the soybean milk is difficult to control and the industrial production is difficult.

In the prior art, the process is complex, and only the physical properties of the bean curd, namely whether the frozen tolerance of the bean curd exists or not, are considered, and the taste and the bean flavor of the bean curd are not pursued.

Disclosure of Invention

The invention aims to provide a preparation process of bean curd and the bean curd, wherein the soft bean curd prepared by the preparation process of the bean curd has tender and smooth mouthfeel after thawing, has aromatic bean flavor, reduces the influence of freezing on the mouthfeel and bean flavor of the soft bean curd, and is convenient for industrial production.

To achieve the purpose, the invention adopts the following technical scheme:

the preparation process of the bean curd comprises the following steps:

s1, preparing soybean milk, wherein the soybean milk is prepared by taking beans as raw materials;

s2, preparing a modified liquid, and adding curdlan, modified starch, white granulated sugar and glucolactone into water to obtain the modified liquid;

s3, adding the modified liquid into the soybean milk at the first temperature to obtain a process product;

s4, heating the process product to a second temperature, preserving heat for a first time, and cooling to obtain the soft bean curd.

Through adopting foretell technical scheme, add curdlan, deformation starch, white granulated sugar and glucolactone in the soybean milk of first temperature and form qualified process article, soybean milk temperature is too low, and then modified starch can not gelatinize completely, and process article takes place to precipitate easily and causes the bean curd layering, and soybean milk temperature is too high, because modified starch gelatinizes too fast, the viscosity of process article can increase fast, leads to the process article inhomogeneous, that have the deposit that the heating formed, the texture is variation. And heating the processed product at a second temperature, wherein the curdlan in the processed product forms irreversible gel under the combined action of the modified starch, the white granulated sugar and the glucolactone, and the irreversible gel has good property, and the soft bean curd is kept to have no holes after being frozen, so that the soft bean curd after being thawed is ensured to have fine taste.

Optionally, the soybean milk is 100 parts by weight, the curdlan used for preparing the modified liquid is 0.1-2 parts by weight, the modified starch is 3-6 parts by weight, the white granulated sugar is 0.5-1 part by weight, the glucolactone is 0.3-2 parts by weight, and the water is 10-20 parts by weight.

By adopting the technical scheme, the mouth feel of the unfrozen soft bean curd can be kept proper. The proportion of the modified liquid and the soybean milk can obviously influence the preparation of the bean curd, the modified starch content in the modified liquid is too high, the process product is difficult to gelatinize, the effect of the curdlan in the preparation of the bean curd is influenced if the white granulated sugar content is too high, the strength of the soft bean curd caused by the gel effect is high if the curdlan content is too high, the taste is hardened, the essence of the soft bean curd is deviated, and the bean curd does not have the effect of fine taste after thawing.

Optionally, the modified starch is phosphate di-starch.

By adopting the technical scheme, the unfrozen bean curd has the end face shape without air holes, has no difference between taste and fresh tender bean curd, and has very sufficient bean fragrance and no beany flavor.

Optionally, the first temperature is in the range of 60-80 ℃.

By adopting the technical scheme, the modified starch has good gelatinization and good uniformity of process products, so that the prepared bean curd has good uniformity.

Optionally, the second temperature is in the range of 80-100 ℃.

By adopting the technical scheme, the curdlan forms irreversible gel with good property under the combined action of the modified starch, the white granulated sugar and the glucolactone, so that the bean curd without holes and with fine taste is formed.

Optionally, the first time is in the range of 10-30 min.

By adopting the technical scheme, the protein denaturation and solidification requirements in the process product are met, and the formed soft bean curd is obtained.

Optionally, the method further comprises the following steps: and S5, freezing the cut soft bean curd.

By adopting the technical scheme, the prepared soft bean curd is cut and preserved.

Optionally, the step S1 includes:

s101, soaking black beans or soybeans in water to obtain wet soybeans;

s102, filtering slag after grinding the wet beans and water together to obtain slurry with a first concentration;

and S103, heating the slurry at a third temperature for a second time to obtain the soybean milk.

By adopting the technical scheme, black beans or soybeans are used as raw materials of soybean milk, soybean bodies are softened by water, so that wet beans which are convenient to grind are obtained, the concentration of the slurry is kept to be a first concentration by grinding the wet beans in a certain amount of water, and the content of soluble solids in the soybean milk can be controlled by controlling the first concentration, so that the method has an important influence on the preparation of the bean curd required in the later period. Heating the slurry at a third temperature for a second time period can denature proteins in the slurry to form floc for subsequent preparation of tofu.

Optionally, the first concentration is 8-12 degrees.

The concentration of the soybean milk is controlled by controlling the first concentration, and the gel-formed bean curd has less air holes and good taste after being frozen at the concentration.

In order to achieve the above purpose, the present invention also adopts the following technical scheme:

the bean curd is prepared by adopting the bean curd preparation process.

The beneficial effects are that:

according to the bean curd preparation process and the bean curd, the cross section of the frozen bean curd after thawing is free of holes under the combined action of the curdlan, the modified starch, the white granulated sugar, the glucolactone and the soybean milk by controlling the process time and the process temperature, so that the thawed bean curd keeps the tender and smooth taste before thawing, the soybean milk is made of bean raw materials, the bean flavor is aromatic, and the white granulated sugar has the effect of relieving the sour taste of the frozen bean curd, so that the bean flavor of the bean curd after thawing is highlighted.

Drawings

FIG. 1 is a texture analysis curve of commercially available fresh bean curd;

FIG. 2 is a texture analysis curve of the soft bean curd prepared in example 1;

FIG. 3 is a graph showing the thawing loss of the prior art tofu in comparison with the tofu prepared in example 1.

Detailed Description

The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.

The embodiment provides a bean curd preparation process, which comprises the following steps:

s1, preparing soybean milk, wherein the soybean milk is prepared by taking beans as raw materials; in this example, the legume material is high quality soybeans or peeled black beans, the protein content is greater than 44%, and the beans are soaked in water for 4-14 hours, such as 6 hours, after washing, and the wet beans weight is increased to 1.5-2.5 times, such as 2 times, of the dry beans. Grinding and crushing the soaked wet beans with 2-5 times (e.g., 3 times) amount of water by a grinder, and separating by a filter screen to obtain soybean milk with a first concentration, wherein the protein content measured by a glycometer is measured in degrees, and the first concentration is 8-12 degrees (e.g., 9 degrees), and in the embodiment, the measurement of the soybean milk concentration is realized by a soybean milk concentration meter. The soymilk is heated to a third temperature (e.g., 95 ℃) by a heating device and maintained for a second time (e.g., 5 minutes) to obtain soymilk.

S2, preparing a modified liquid, and adding curdlan, modified starch, white granulated sugar and glucolactone into water to obtain the modified liquid; the modified starch comprises oxidized starch, phosphate starch, etherified starch, crosslinked starch, physically modified starch, etc., and is prepared from tapioca starch, wheat flour starch, potato starch, corn starch, waxy corn starch, etc. Preferably, the modified starch is phosphate di-starch.

Curdlan is a water-insoluble glucan made up of beta-1, 3-glycosidic bonds produced by microorganisms and is readily dispersible in cold water. It can make the thawed bean curd taste smoother. In the embodiment, the weight (g) is counted, the soybean milk is 100 parts, the curdlan is 0.1-2 parts, the modified starch is 3-6 parts, the white granulated sugar is 0.5-1 part, the glucolactone is 0.3-2 parts, and the water is 10-20 parts.

S3, adding the modified liquid into the soybean milk at the first temperature to obtain a process product; the first temperature is in the range of 60-80deg.C, and if the temperature of soybean milk is below 60deg.C during mixing, the modified starch cannot be completely gelatinized, and precipitation easily occurs to cause delamination of bean curd. If the temperature is higher than 80 ℃, the viscosity of the soybean milk increases rapidly due to the too rapid gelatinization of the modified starch, resulting in deterioration of the formed bean curd.

S4, heating the processed product to a second temperature, preserving heat for a first time, and cooling to obtain the soft bean curd. The processed product can be heated by steaming to coagulate into soft bean curd. Preferably, the second temperature is in the range 80-100 ℃, and the curdlan, due to its unique properties, can form gels with completely different properties when heated to different temperatures: low gel and high gel. The aqueous dispersion of curdlan is heated to about 55-65 ℃ and then cooled to below 40 ℃ to form a thermoreversible low-grade gel which has low strength and is not suitable for use in the present invention. When the aqueous dispersion of curdlan is heated to a temperature above 80 ℃, a thermoreversible gel is formed, which has good properties and is suitable for use in the present invention. Optionally, the first time is in the range of 10-30min, which is selected according to the selection of the second temperature. In this embodiment, the first time is 20 minutes when the second temperature is 90 ℃. After the first time of heat preservation, the coagulated and formed soft bean curd can be naturally cooled, and can also be put into cold water for cooling.

And S5, freezing the cut tender bean curd. Cutting and packaging the cooled soft bean curd, and directly putting into a freezing warehouse at-18 ℃ for freezing storage.

The embodiment also provides the bean curd prepared by the bean curd preparation process.

According to the bean curd preparation process and the bean curd, the prepared soft bean curd can keep a tender and smooth taste after being frozen and thawed by adding the curdlan in the preparation process, is quite similar to the soft bean curd, is resistant to boiling and is not easy to break. White granulated sugar is added in the preparation process of the bean curd, so that the bean flavor of the bean curd is more intense. The glucose lactone is adopted as the coagulant, the coagulation speed is slower than that of calcium sulfate and magnesium chloride, and the coagulation starts about 5 minutes, so that the method is suitable for industrial mass production.

Example 1

(1) 10kg of high-quality peeled black beans are screened, washed for 2 times, added with water of 25 ℃ and 30kg, and soaked for 6 hours. Pouring the soaked peeled black beans into a grinder, grinding with water of 50kg at 25 ℃ and filtering to obtain soybean milk of about 9 ℃. Pouring the soybean milk into a jacketed kettle, heating to 95 ℃, and keeping for 5 minutes to obtain about 50kg of finished soybean milk.

(2) A modified solution was prepared, and phosphate double starch (2.5 kg), curdlan (0.25 kg), white granulated sugar (0.3 kg) and glucolactone (0.3 kg) were poured into water (5 kg) at 25℃and stirred well for use.

(3) Cooling the finished soybean milk to 70 ℃, pouring the modified liquid into the finished soybean milk, stirring uniformly, moving the process product, pouring the process product into steaming trays of 3kg each, and steaming the steaming trays in a steaming box at 90 ℃ for 20 minutes.

(4) Soaking the steamed soft bean curd in clean cold water, cooling to normal temperature, cutting into blocks, packaging, and storing in-18deg.C freezer.

Example 2

The difference between this example and example 1 is that in step (1) of this example, peeled black beans after soaking were ground with water at 25℃and 60kg, instead of grinding with water at 25℃and 50 kg.

Example 3

The difference between this example and example 1 is that in step (2) of this example, the phosphate di-starch is replaced with acetate starch.

Example 4

The difference between this example and example 1 is that in step (3) of this example, the final soymilk was cooled to 80 ℃ instead of 70 ℃.

Example 5

The difference between this example and example 1 is that in step (3) of this example, the process product was steamed at 100℃instead of 90 ℃.

Comparative example 1

The difference between this example and example 1 is that in step (2) of this example, the glucide is replaced with calcium sulfate. By comparing the appearances of the tofu prepared in comparative example 1 with those of the tofu prepared in example 1, the tofu prepared in comparative example 1 had a rough appearance and large pores, and the tender and slippery characteristics of the tofu were reduced.

Comparative example 2

The difference between this example and example 1 is that in step (2) of this example, the curdlan is replaced with a high acyl gellan gum. By comparing the appearances of the tofu prepared in comparative example 2 and example 1, the tofu prepared in comparative example 2 had a rough appearance, large pores, and reduced tender and slippery characteristics.

Comparative example 3

The difference between this example and example 1 is that white sugar is not added in step (2) of this example.

Comparative example 4

The difference between this example and example 1 is that in step (2) of this example, the phosphate di-starch is replaced with corn starch.

Analysis of Bean curd texture

After heating the commercial fresh bean curd and the soft bean curd (not frozen) produced in this example 1 in boiling water for 5 minutes, the whole texture TPA curve was obtained by testing using a texture analyzer, and as can be seen from the respective texture patterns, the texture curve of the soft bean curd produced in this example 1 is very similar to that of the commercial fresh, not-frozen ordinary bean curd.

The texture analysis was performed on the soft bean curd prepared in this example 1, and then the soft bean curd was quick-frozen (condition-35 ℃) and then the texture analysis was performed again after the frozen bean curd was sufficiently thawed, to obtain a texture analysis comparison table as shown in table 1. Wherein, hardness refers to the force required to deform the material to a certain extent, elasticity refers to the ratio of the deformed material to the original state after the force is removed, cohesiveness refers to the amount of internal binding force required to form the sample form, and chewiness refers to the energy required to chew a solid food into a swallowable state. As can be seen from the data in Table 1, the fresh bean curd has a smaller difference from the frozen and thawed bean curd in the above data, and shows the characteristics of the bean curd in a fresh state after being frozen and thawed, thereby maintaining the taste and flavor of the soft bean curd. The soft bean curd prepared by the preparation process of the bean curd provided in the embodiment 1 has moderate hardness, moderate elasticity, good taste, high cohesiveness, difficult shattering and high chewiness.

Table 1 texture analysis comparison table

(II) thawing loss analysis

The tofu prepared by combining the prior art lactone tofu, marinated tofu, lactone and marinated tofu was subjected to freezing and thawing tests under the same conditions as those of the tofu prepared in example 1, and the weight loss after thawing was measured and calculated, and the results are shown in fig. 3. The weight loss ratio (ratio of weight after thawing to weight before thawing) of the tofu prepared in this example 1 was about 4%, the weight loss ratio of lactone tofu was about 49%, the weight loss ratio of brine tofu was about 14%, and the weight loss ratio of tofu prepared by combining lactone and brine coagulants was about 20%, as a result, the thawing loss of tofu prepared by the process provided in this example was minimized, thereby making it close to the quality before thawing.

(III) Bean curd sensory evaluation test

The items of sensory evaluation mainly include the following three items: texture, taste bean flavor and taste. For the same evaluation item of the same sample, 10 trained panelists were randomly found to evaluate, and then one evaluation item of one sample had 10 evaluation results, the average value of the 10 evaluation results was calculated, and the calculation results were counted in the following table. Each evaluation item of each sample is performed in such a manner until evaluation of all the evaluation items of all the samples is completed.

The soft bean curd prepared in examples 1 to 5 and comparative examples 1 to 4 was frozen and then boiled in boiling water for 5 minutes to be sufficiently thawed, and sensory evaluation was performed, with specific evaluation criteria shown in Table 2, and evaluation results shown in Table 3.

TABLE 2 sensory evaluation criteria Table

Table 3 sensory evaluation results table

Examples	Tissue morphology	Taste of taste	Tasting bean flavor
				Example 1	2.8	2.8	2.9
Example 2	2	2.3	2.5
				Example 3	2.2	2.3	2.8
Example 4	1.8	2	2.2
				Example 5	2	2.1	2.3
Comparative example 1	2	1.8	2.1
				Comparative example 2	2.3	2.1	2.4
Comparative example 3	2.2	1.7	1.4
				Comparative example 4	1.3	1.3	1.4

With a score of 2 as a pass score, it can be seen that examples 1, 2, 3, 5 and comparative example 2 all perform well, wherein example 1 obtained the best value for each evaluation, which is the best example.

The tofu in comparative example 2 was lower in texture, mouthfeel and bean flavor than example 1, indicating that curdlan has a gain effect on texture, mouthfeel and bean flavor of tofu compared to high acyl gellan gum.

The bean curd of comparative example 3 is lower in bean flavor than that of example 1, which means that granulated sugar can effectively enhance bean flavor and reduce beany flavor.

(IV) soymilk set time test

The coagulation reaction state of soymilk in step (4) in examples 1 to 5, comparative examples 1 to 4 was evaluated by visual observation by a person skilled in the art, and the time of coagulation of soymilk was measured by a timer to obtain table 4.

Table 4 soymilk set time table

As can be seen from Table 4, the soybean milk of comparative example 1 has a lower setting time than that of example 1, indicating that the setting rate of glucolactone to soybean milk is slower than that of calcium sulfate, and is easy to control, and is more suitable for industrial production. The soybean milk of example 4 has a lower setting time than that of example 1, and the lower temperature of the final soybean milk of step (3) can slow down the setting speed of the bean curd produced in step (4).

The solidification time of the soybean milk is less than 2 minutes, and the large-scale industrial production is basically impossible. The soybean milk of examples 1 to 5 and comparative examples 1 to 4 are solidified in more than 3 minutes, and industrial production can be realized, wherein the soybean milk of examples 1,3 and 5 and comparative examples 3 and 4 are solidified in more than 6 minutes, the soybean milk solidification time is long, and the industrial operability is higher.

According to the invention, through the mutual matching of the curdlan, the white granulated sugar, the glucolactone modified starch and the soybean milk, the prepared bean curd has no pores after thawing, fine taste and rich and sufficient bean flavor. Meanwhile, the process is simple, the soybean milk solidification time is sufficient, and the industrial production is convenient.

It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Various obvious changes, rearrangements and substitutions can be made by those skilled in the art without departing from the scope of the invention. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims (10)

1. The preparation process of the bean curd is characterized by comprising the following steps of:

s1, preparing soybean milk, wherein the soybean milk is prepared by taking beans as raw materials;

s2, preparing a modified liquid, and adding curdlan, modified starch, white granulated sugar and glucolactone into water to obtain the modified liquid;

s3, adding the modified liquid into the soybean milk at the first temperature to obtain a process product;

s4, heating the process product to a second temperature, preserving heat for a first time, and cooling to obtain the soft bean curd.

2. The process for preparing bean curd as claimed in claim 1, wherein the soybean milk is 100 parts by weight, the curdlan used for preparing the modified liquid is 0.1-2 parts by weight, the modified starch is 3-6 parts by weight, the white granulated sugar is 0.5-1 part by weight, the glucolactone is 0.3-2 parts by weight, and the water is 10-20 parts by weight.

3. The process for preparing bean curd as claimed in claim 1, wherein the modified starch is phosphate di-starch.

4. The process for preparing bean curd as claimed in claim 1, wherein the first temperature is in the range of 60-80 ℃.

5. The process for preparing bean curd as claimed in claim 1, wherein the second temperature is in the range of 80-100 ℃.

6. The process for preparing bean curd as claimed in claim 1, wherein the first time is in the range of 10-30 min.

7. The process for preparing bean curd as claimed in claim 1, further comprising the steps of: and S5, freezing the cut soft bean curd.

8. The process for preparing bean curd as claimed in claim 1, wherein the step S1 comprises:

s101, soaking black beans or soybeans in water to obtain wet soybeans;

s102, filtering slag after grinding the wet beans and water together to obtain slurry with a first concentration;

and S103, heating the slurry at a third temperature for a second time to obtain the soybean milk.

9. The process for preparing bean curd as claimed in claim 8, wherein the first concentration is 8-12 degrees.

10. Tofu, characterized in that it is prepared by the tofu preparation process according to any one of claims 1 to 9.

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