Tough tofu and production process thereof

Abstract

The invention relates to the technical field of food processing, and particularly discloses tough tofu and a production process thereof. Dendrobium officinale residues are added, so that the content of dietary fibers in the tofu is increased, and meanwhile, a certain herbal flavor is added to the tofu; considering that the texture characteristics of the bean curd become poor due to addition of dendrobium officinale residues, a coagulator compounded from dendrobium officinale fermentation liquor and gluconic acid-delta-lactone is adopted, and a dendrobium officinale extracting solution is subjected to fermentation treatment through beer yeast, so that the content of phenolic acid substances in the extracting solution is increased, and the quality of the bean curd is improved. Then dendrobium officinale fermentation liquor is used as an acidic coagulator, macromolecular chains in the soybean milk are gathered due to electrostatic force and hydrophobic interaction by acidic substances in the dendrobium officinale fermentation liquor, and then are connected through other molecular forces such as disulfide bonds, hydrogen bonds and ionic bonds to form a gel network structure, so that the bean curd has a certain water retention rate; meanwhile, the porous structure of the dendrobium officinale residues also increases the water holding rate of the bean curd to a certain extent.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to tough tofu and a production process thereof. Background Art

[0002] Traditional tofu is a soy product made from soybeans as the main raw material. Soy milk is obtained after cleaning, soaking, grinding and filtering, and then boiled, added with coagulants and formed. Its core processing steps rely on the interaction of soy protein with coagulants (such as calcium sulfate, magnesium chloride or glucono-δ-lactone) after heating and denaturation to form a gel network structure, thus giving tofu a unique texture and gel strength. However, in order to ensure the gel performance, the existing process requires thorough filtration of bean dregs after grinding to remove insoluble dietary fiber. At the same time, in the subsequent pressing and molding process, a large amount of soluble dietary fiber is lost with water, which ultimately leads to an extremely low dietary fiber content in tofu, which is difficult to meet the nutritional functionalization needs of modern food.

[0003] Among traditional coagulants, gypsum (calcium sulfate) easily makes tofu too hard and astringent, brine (magnesium chloride) solidifies too quickly, resulting in poor process controllability and introducing bitterness, and although glucono-δ-lactone can improve the taste, the gel strength it forms is weak and easily produces sour taste. All three are difficult to take into account both gel quality and flavor characteristics. How to make tofu rich in dietary fiber while ensuring gel strength has become an important research direction in this field.

[0004] For example, Chinese patent document CN101248857A discloses a method for producing dietary fiber tofu, including the steps of peeling, soaking, washing, grinding, boiling, emulsifying, homogenizing, slurrying, filling and finished products. This method does not separate the dregs, but further grinds the slurry with a colloid mill to refine the fibers after grinding, emulsifies the ultra-finely treated soy milk with glycerides and phospholipids in a high-speed shearing machine, and then performs two-stage homogenization, and finally performs slurrying with a coagulant such as edible brine, lactone or gypsum. Although tofu containing dietary fiber can be obtained, the effect is not ideal. Low protein gel strength often occurs in tofu production and processing, resulting in the product being fragile, the cross-section being in the shape of dregs, and having a rough taste. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention aims to provide a tough tofu and a production process.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A production process of tough tofu comprises the following steps:

[0008] S1. Preparation of soy milk

[0009] The soybeans are soaked, ground, filtered and boiled to obtain soy milk.

[0010] In this step, large, uniform, plump, mildew-free and impurity-free soybeans are selected as raw materials, and the soybeans are soaked in water for 8-12 hours at a material-water ratio of 1:4-8;

[0011] After soaking, the soaked soybeans are added to a grinder, and water is added according to a soybean-water ratio of 1:4-6 based on the dry weight of the soybeans, and the grinding is performed for 2-3 times;

[0012] Filter the slurry with a 200-mesh filter cloth while stirring;

[0013] The filtered slurry is boiled over high heat to 90-95°C, stirring while heating, and maintained for 3-5 minutes to obtain soy milk.

[0014] S2. Preparation of mixed solution

[0015] After the soy milk is cooled, add the Dendrobium officinale residue and the egg white liquid thereto, mix well, and obtain a mixed liquid.

[0016] In this step, the soy milk is cooled to 40-45°C, at which time the protein in the egg white liquid will not denature and coagulate, and can be fully mixed with the soy milk.

[0017] In this step, the dosage ratio of the soy milk, the Dendrobium officinale residue and the egg white liquid is 100mL:4-8g:10-20mL.

[0018] Specifically, the preparation method of the Dendrobium officinale slag is as follows: grinding the dry Dendrobium officinale material, then adding distilled water at a material-water ratio of 1:20-30 for high-pressure extraction, and filtering to obtain the Dendrobium officinale slag and the Dendrobium officinale extract.

[0019] More specifically, the pressure of high-pressure extraction is 0.5-1MPa, for example, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, and 1MPa can be selected; the temperature of high-pressure extraction is 80-100°C, for example, 80°C, 85°C, 90°C, 95°C, and 100°C can be selected; the time of high-pressure extraction is 30-60min, for example, 30min, 35min, 40min, 45min, 50min, 55min, and 60min can be selected, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] The Dendrobium officinale extract obtained in this step is used for subsequent fermentation.

[0021] S3. Preparation of tough tofu

[0022] The mixed liquid is heated, and then a coagulant is added, dispersed evenly, and cooled and solidified to obtain tough tofu.

[0023] In this step, the specific process of heating is: heating at 80-100° C. for 10-30 minutes.

[0024] In this step, the dosage ratio of the mixed liquid and the coagulant is 100mL:2-4g, for example, 100mL:2g, 100mL:2.5g, 100mL:3g, 100mL:3.5g, 100mL:4g can be selected, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Specifically, the coagulant includes Dendrobium officinale fermentation liquid and glucono-δ-lactone.

[0026] More specifically, the mass ratio of the Dendrobium officinale fermentation liquid to glucono-δ-lactone is 10-15:1-2, for example, 10:1, 10:2, 12:1, 12:2, 15:1, 15:2 can be selected, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] The preparation method of the Dendrobium officinale fermentation liquid is as follows: brewer's yeast is inoculated into the Dendrobium officinale extract, fermented and cultured, and after the fermentation and culture is completed, high-temperature sterilization is performed, and the filtrate is filtered and collected to obtain the Dendrobium officinale fermentation liquid.

[0028] Specifically, the fermentation culture temperature is 28-32°C, for example, 28°C, 29°C, 30°C, 31°C, and 32°C can be selected; the fermentation culture time is 6-12h, for example, 6h, 7h, 8h, 9h, 10h, 11h, and 12h can be selected, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] Specifically, based on the volume of the Dendrobium officinale extract, the inoculation amount of brewer's yeast is 1-3%, wherein the number of live bacteria of brewer's yeast is ≥ 1.0×10 9 cfu / mL.

[0030] The invention also provides tough tofu prepared by the production process.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The production process of tough tofu provided by the present invention increases the content of dietary fiber in tofu by adding Dendrobium officinale residue, and also adds a certain herbal flavor to the tofu; considering that the addition of Dendrobium officinale residue causes the texture characteristics of tofu to deteriorate, the present invention adopts a coagulant prepared by a compound of Dendrobium officinale fermentation liquid and glucono-δ-lactone, and ferments the Dendrobium officinale extract with brewer's yeast to increase the content of phenolic acid substances in the extract, and then uses the Dendrobium officinale fermentation liquid as an acidic coagulant. The acidic substances in the Dendrobium officinale fermentation liquid cause the macromolecular chains in the soy milk to aggregate due to electrostatic force and hydrophobic interaction, and then connect through other molecular forces such as disulfide bonds, hydrogen bonds, and ionic bonds to form a gel network structure, so that the tofu has a certain water holding rate; at the same time, the porous structure of the Dendrobium officinale residue also increases the water holding rate of the tofu to a certain extent.

[0033] (2) The inventors also found during the experiment that fermenting the Dendrobium officinale extract with brewer's yeast was more effective in making tofu than fermenting with Lactobacillus plantarum and Bacillus subtilis. The reason may be that the properties of tofu gel induced by different types of organic acids are different, and the organic acids in the Dendrobium officinale fermentation liquid obtained by brewer's yeast fermentation are more suitable for making tofu.

[0034] (3) The production process provided by the present invention prepares a high-dietary fiber tofu with good herbal flavor, which is rich in nutrition and has good elasticity and toughness, low cooking loss, simple production process, and is conducive to promotion and use. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0036] It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention were purchased through commercial channels.

[0037] The brewer's yeast and Lactobacillus plantarum used in the examples of the present invention are both from Henan Bohao Food Additive Co., Ltd.

[0038] Example 1

[0039] A production process of tough tofu comprises the following steps:

[0040] S1. Select soybeans that are large, uniform, full, mildew-free and free of impurities as raw materials, soak the soybeans in water at a material-water ratio of 1:5 for 12 hours, add the soaked soybeans into a grinder after soaking, add water at a soybean-water ratio of 1:5 based on the dry weight of the soybeans, grind the soybeans for 3 times, filter the slurry with a 200-mesh filter cloth, filter while stirring, boil the filtered slurry over high heat to 95° C., heat and stir for 3 minutes, and obtain soy milk;

[0041] S2, cooling the soy milk to 40° C., adding the Dendrobium officinale residue and the egg white liquid thereto, wherein the amount ratio of the soy milk, the Dendrobium officinale residue and the egg white liquid is 100 mL:5 g:15 mL, and mixing well to obtain a mixed solution;

[0042] The preparation method of Dendrobium officinale slag is as follows: grinding the dry material of Dendrobium officinale, passing it through a 200-mesh sieve, and then adding distilled water at a material-water ratio of 1:25 for high-pressure extraction, wherein the pressure of the high-pressure extraction is 0.5MPa, the temperature of the high-pressure extraction is 90°C, the time of the high-pressure extraction is 45min, and filtering is performed to obtain Dendrobium officinale slag and Dendrobium officinale extract;

[0043] S3, heating the mixed solution at 90°C for 20 minutes, then adding a coagulant, dispersing evenly, and cooling and solidifying to obtain tough tofu, wherein the ratio of the mixed solution to the coagulant is 100mL:3g, and the coagulant is composed of Dendrobium officinale fermentation liquid and glucono-δ-lactone in a mass ratio of 10:1;

[0044] The preparation method of Dendrobium officinale fermentation liquid is as follows: brewer's yeast is inoculated into the Dendrobium officinale extract, and the inoculation amount of brewer's yeast is 3% based on the volume of the Dendrobium officinale extract, and the number of live bacteria of brewer's yeast is 1.0×10 9 cfu / mL, ferment and culture at 30℃ for 12h, sterilize at high temperature after the fermentation and collect the filtrate by filtration to obtain the fermentation liquid of Dendrobium officinale.

[0045] Example 2

[0046] A production process of tough tofu comprises the following steps:

[0047] S1. Select soybeans that are large, uniform, full, mildew-free and free of impurities as raw materials, soak the soybeans in water at a material-water ratio of 1:5 for 12 hours, add the soaked soybeans into a grinder after soaking, add water at a soybean-water ratio of 1:5 based on the dry weight of the soybeans, grind the soybeans for 3 times, filter the slurry with a 200-mesh filter cloth, filter while stirring, boil the filtered slurry over high heat to 95° C., heat and stir for 3 minutes, and obtain soy milk;

[0048] S2, cooling the soy milk to 40° C., adding the Dendrobium officinale residue and the egg white liquid thereto, wherein the amount ratio of the soy milk, the Dendrobium officinale residue and the egg white liquid is 100 mL:4 g:10 mL, and mixing well to obtain a mixed solution;

[0049] The preparation method of Dendrobium officinale slag is as follows: grinding the dry material of Dendrobium officinale, passing it through a 200-mesh sieve, and then adding distilled water at a material-water ratio of 1:25 for high-pressure extraction, wherein the pressure of the high-pressure extraction is 0.5MPa, the temperature of the high-pressure extraction is 90°C, the time of the high-pressure extraction is 45min, and filtering is performed to obtain Dendrobium officinale slag and Dendrobium officinale extract;

[0050] S3, heating the mixed solution at 90° C. for 20 min, then adding a coagulant, dispersing evenly, and cooling and coagulating to obtain tough tofu, wherein the ratio of the mixed solution to the coagulant is 100 mL: 2 g, and the coagulant is composed of Dendrobium officinale fermentation liquid and glucono-δ-lactone in a mass ratio of 10:2;

[0051] The preparation method of Dendrobium officinale fermentation liquid is as follows: brewer's yeast is inoculated into the Dendrobium officinale extract, and the inoculation amount of brewer's yeast is 3% based on the volume of the Dendrobium officinale extract, and the number of live bacteria of brewer's yeast is 1.0×10 9 cfu / mL, ferment and culture at 30℃ for 12h, sterilize at high temperature after the fermentation and collect the filtrate by filtration to obtain the fermentation liquid of Dendrobium officinale.

[0052] Example 3

[0053] A production process of tough tofu comprises the following steps:

[0054] S1. Select soybeans that are large, uniform, full, mildew-free and free of impurities as raw materials, soak the soybeans in water at a material-water ratio of 1:5 for 12 hours, add the soaked soybeans into a grinder after soaking, add water at a soybean-water ratio of 1:5 based on the dry weight of the soybeans, grind the soybeans for 3 times, filter the slurry with a 200-mesh filter cloth, filter while stirring, boil the filtered slurry over high heat to 95° C., heat and stir for 3 minutes, and obtain soy milk;

[0055] S2, cooling the soy milk to 40° C., adding the Dendrobium officinale residue and the egg white liquid thereto, wherein the amount ratio of the soy milk, the Dendrobium officinale residue and the egg white liquid is 100 mL:8 g:20 mL, and mixing well to obtain a mixed solution;

[0056] The preparation method of Dendrobium officinale slag is as follows: grinding the dry material of Dendrobium officinale, passing it through a 200-mesh sieve, and then adding distilled water at a material-water ratio of 1:25 for high-pressure extraction, wherein the pressure of the high-pressure extraction is 0.5MPa, the temperature of the high-pressure extraction is 90°C, the time of the high-pressure extraction is 45min, and filtering is performed to obtain Dendrobium officinale slag and Dendrobium officinale extract;

[0057] S3, heating the mixed solution at 90°C for 20 minutes, then adding a coagulant, dispersing evenly, and cooling and solidifying to obtain tough tofu, wherein the ratio of the mixed solution to the coagulant is 100mL:4g, and the coagulant is composed of Dendrobium officinale fermentation liquid and glucono-δ-lactone in a mass ratio of 15:1;

[0058] The preparation method of Dendrobium officinale fermentation liquid is as follows: brewer's yeast is inoculated into the Dendrobium officinale extract, and the inoculation amount of brewer's yeast is 3% based on the volume of the Dendrobium officinale extract, and the number of live bacteria of brewer's yeast is 1.0×10 9 cfu / mL, ferment and culture at 30℃ for 12h, sterilize at high temperature after the fermentation and collect the filtrate by filtration to obtain the fermentation liquid of Dendrobium officinale.

[0059] Example 4

[0060] A production process of tough tofu comprises the following steps:

[0061] S1. Select soybeans that are large, uniform, full, mildew-free and free of impurities as raw materials, soak the soybeans in water at a material-water ratio of 1:5 for 12 hours, add the soaked soybeans into a grinder after soaking, add water at a soybean-water ratio of 1:5 based on the dry weight of the soybeans, grind the soybeans for 3 times, filter the slurry with a 200-mesh filter cloth, filter while stirring, boil the filtered slurry over high heat to 95° C., heat and stir for 3 minutes, and obtain soy milk;

[0062] S2, cooling the soy milk to 40° C., adding the Dendrobium officinale residue and the egg white liquid thereto, wherein the amount ratio of the soy milk, the Dendrobium officinale residue and the egg white liquid is 100 mL:6 g:16 mL, and mixing well to obtain a mixed solution;

[0063] The preparation method of Dendrobium officinale slag is as follows: grinding the dry material of Dendrobium officinale, passing it through a 200-mesh sieve, and then adding distilled water at a material-water ratio of 1:25 for high-pressure extraction, wherein the pressure of the high-pressure extraction is 0.5MPa, the temperature of the high-pressure extraction is 90°C, the time of the high-pressure extraction is 45min, and filtering is performed to obtain Dendrobium officinale slag and Dendrobium officinale extract;

[0064] S3, heating the mixed solution at 90° C. for 20 min, then adding a coagulant, dispersing evenly, and cooling and solidifying to obtain tough tofu, wherein the ratio of the mixed solution to the coagulant is 100 mL: 2.5 g, and the coagulant is composed of Dendrobium officinale fermentation liquid and glucono-δ-lactone in a mass ratio of 15:2;

[0065] The preparation method of Dendrobium officinale fermentation liquid is as follows: brewer's yeast is inoculated into the Dendrobium officinale extract, and the inoculation amount of brewer's yeast is 1% based on the volume of the Dendrobium officinale extract, and the number of live bacteria of brewer's yeast is 1.0×10 9 cfu / mL, ferment and culture at 30℃ for 12h, sterilize at high temperature after the fermentation and collect the filtrate by filtration to obtain the fermentation liquid of Dendrobium officinale.

[0066] Comparative Example 1

[0067] A production process of tough tofu comprises the following steps:

[0068] S1. Select soybeans that are large, uniform, full, mildew-free and free of impurities as raw materials, soak the soybeans in water at a material-water ratio of 1:5 for 12 hours, add the soaked soybeans into a grinder after soaking, add water at a soybean-water ratio of 1:5 based on the dry weight of the soybeans, grind the soybeans for 3 times, filter the slurry with a 200-mesh filter cloth, filter while stirring, boil the filtered slurry over high heat to 95° C., heat and stir for 3 minutes, and obtain soy milk;

[0069] S2, cooling the soybean milk to 40° C., adding the egg white liquid thereto, wherein the ratio of the soybean milk to the egg white liquid is 100 mL:15 mL, and mixing evenly to obtain a mixed solution;

[0070] S3, heating the mixed solution at 90°C for 20 minutes, then adding a coagulant, dispersing evenly, and cooling and solidifying to obtain tough tofu, wherein the ratio of the mixed solution to the coagulant is 100mL:3g, and the coagulant is composed of Dendrobium officinale fermentation liquid and glucono-δ-lactone in a mass ratio of 10:1;

[0071] The preparation method of Dendrobium officinale fermentation liquid is as follows: brewer's yeast is inoculated into the Dendrobium officinale extract, and the inoculation amount of brewer's yeast is 3% based on the volume of the Dendrobium officinale extract, and the number of live bacteria of brewer's yeast is 1.0×10 9 cfu / mL, ferment and culture at 30℃ for 12h, sterilize at high temperature after the fermentation and collect the filtrate by filtration to obtain the fermentation liquid of Dendrobium officinale.

[0072] Compared with Example 1, Comparative Example 1 did not add Dendrobium officinale slag.

[0073] Comparative Example 2

[0074] A production process of tough tofu comprises the following steps:

[0075] S1. Select soybeans that are large, uniform, full, mildew-free and free of impurities as raw materials, soak the soybeans in water at a material-water ratio of 1:5 for 12 hours, add the soaked soybeans into a grinder after soaking, add water at a soybean-water ratio of 1:5 based on the dry weight of the soybeans, grind the soybeans for 3 times, filter the slurry with a 200-mesh filter cloth, filter while stirring, boil the filtered slurry over high heat to 95° C., heat and stir for 3 minutes, and obtain soy milk;

[0076] S2, cooling the soy milk to 40° C., adding the Dendrobium officinale residue and the egg white liquid thereto, wherein the amount ratio of the soy milk, the Dendrobium officinale residue and the egg white liquid is 100 mL:5 g:15 mL, and mixing well to obtain a mixed solution;

[0077] The preparation method of Dendrobium officinale slag is as follows: grinding the dry material of Dendrobium officinale, passing it through a 200-mesh sieve, and then adding distilled water at a material-water ratio of 1:25 for high-pressure extraction, wherein the pressure of the high-pressure extraction is 0.5MPa, the temperature of the high-pressure extraction is 90°C, the time of the high-pressure extraction is 45min, and filtering is performed to obtain Dendrobium officinale slag and Dendrobium officinale extract;

[0078] S3. Heat the mixed solution at 90°C for 20 minutes, then add glucono-δ-lactone, disperse evenly, and cool and solidify to obtain tough tofu, wherein the ratio of the mixed solution to glucono-δ-lactone is 100mL:3g.

[0079] Compared with Example 1, Comparative Example 2 did not add Dendrobium officinale fermentation liquid.

[0080] Comparative Example 3

[0081] A production process of tough tofu comprises the following steps:

[0082] S1. Select soybeans that are large, uniform, full, mildew-free and free of impurities as raw materials, soak the soybeans in water at a material-water ratio of 1:5 for 12 hours, add the soaked soybeans into a grinder after soaking, add water at a soybean-water ratio of 1:5 based on the dry weight of the soybeans, grind the soybeans for 3 times, filter the slurry with a 200-mesh filter cloth, filter while stirring, boil the filtered slurry over high heat to 95° C., heat and stir for 3 minutes, and obtain soy milk;

[0083] S2, cooling the soy milk to 40° C., adding the Dendrobium officinale residue and the egg white liquid thereto, wherein the amount ratio of the soy milk, the Dendrobium officinale residue and the egg white liquid is 100 mL:5 g:15 mL, and mixing well to obtain a mixed solution;

[0084] The preparation method of Dendrobium officinale slag is as follows: grinding the dry material of Dendrobium officinale, passing it through a 200-mesh sieve, and then adding distilled water at a material-water ratio of 1:25 for high-pressure extraction, wherein the pressure of the high-pressure extraction is 0.5MPa, the temperature of the high-pressure extraction is 90°C, the time of the high-pressure extraction is 45min, and filtering is performed to obtain Dendrobium officinale slag and Dendrobium officinale extract;

[0085] S3, heating the mixed solution at 90°C for 20 minutes, then adding a coagulant, dispersing evenly, and cooling and solidifying to obtain tough tofu, wherein the ratio of the mixed solution to the coagulant is 100mL:3g, and the coagulant is composed of Dendrobium officinale fermentation liquid and glucono-δ-lactone in a mass ratio of 10:1;

[0086] The preparation method of Dendrobium officinale fermented liquid is as follows: inoculating Lactobacillus plantarum into the Dendrobium officinale extract, the inoculation amount of Lactobacillus plantarum is 3% based on the volume of the Dendrobium officinale extract, and the number of viable Lactobacillus plantarum is 1.0×10 9 cfu / mL, ferment and culture at 30℃ for 12h, sterilize at high temperature after the fermentation and collect the filtrate by filtration to obtain the fermentation liquid of Dendrobium officinale.

[0087] Compared with Example 1, in Comparative Example 3, plant lactobacillus was used to replace brewer's yeast.

[0088] The tofu samples prepared in Example 1 and Comparative Examples 1-3 were subjected to performance tests.

[0089] The texture analysis of tofu samples was carried out using a texture analyzer. The specific steps are as follows: the middle part of the tofu sample was selected and cut into a cube with a length, width and height of 10 mm. The tofu sample was then placed on the stage of the texture analyzer and the position was adjusted so that the center of the sample was aligned with the center of the probe. The selected probe was TA-100. The test conditions were: pre-test speed of 4 mm / s, test speed of 2 mm / s, post-test speed of 2 mm / s, trigger force of 5 g, starting distance of 20 mm, compression ratio of 40%. The experiment was repeated three times and the average value was taken. The test results are shown in Table 1.

[0090] Table 1 Performance table of tofu texture prepared by different groups

[0091] Hardness(N) Cohesion Elasticity(mm) Chewing properties (mJ) Example 1 1.86 0.64 2.73 3.51 Comparative Example 1 1.83 0.65 2.76 3.62 Comparative Example 2 1.32 0.57 2.08 2.46 Comparative Example 3 1.78 0.60 2.55 3.19

[0092] It can be seen from Table 1 that the tofu prepared by the present invention has good texture characteristics. Compared with Comparative Example 1, the texture characteristics of the tofu in this embodiment are not significantly changed by adding Dendrobium officinale residue.

[0093] Determination of water holding capacity of tofu: weigh about 2g of tofu sample, record the mass as W1, place it in a 50mL centrifuge tube with absorbent cotton at the bottom, centrifuge at 3000r / min for 10min and weigh W2, water holding capacity of tofu = (W1-W2) / W1×100%;

[0094] Determination of dietary fiber content: Determination shall be carried out in accordance with the National Food Safety Standard Determination of Dietary Fiber Content in Food GB5009.88-2023;

[0095] Determination of protein content: Kjeldahl nitrogen method, according to the "National Food Safety Standard Determination of Protein in Food" GB5009.5-2016;

[0096] The test results are shown in Table 2.

[0097] Table 2 Results of property determination of tofu prepared by different groups

[0098]

[0099] As can be seen from Table 2, in Comparative Example 1, no Dendrobium officinale residue was added, and although it had a higher protein content, the insoluble dietary fiber content was significantly reduced; in Comparative Example 2, no Dendrobium officinale fermentation liquid was added, and the texture characteristics of the tofu were worse than those in Example 1, and the insoluble dietary fiber content and protein content were also relatively low; in Comparative Example 3, plant lactobacillus was used to replace brewer's yeast, and the texture characteristics, insoluble dietary fiber content and protein content of the tofu were not as good as those in Example 1 of the present invention, indicating that the Dendrobium officinale fermentation liquid obtained by fermentation with brewer's yeast is more suitable for the production of tofu.

[0100] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, some modifications and improvements can be made to the present invention. Therefore, any modification or improvement made without departing from the spirit of the present invention belongs to the scope of protection claimed in the present invention.

Claims

1. A production process for tough tofu, characterized in that: The steps include: S1, soaking, grinding, filtering and boiling soybeans to obtain soybean milk; S2, after the soy milk is cooled, adding the Dendrobium officinale residue and the egg white liquid thereto, mixing evenly to obtain a mixed solution; S3, heating the mixed solution, then adding a coagulant, dispersing it evenly, and cooling and coagulating it to obtain tough tofu, wherein the coagulant comprises a fermented liquid of Dendrobium officinale and glucono-δ-lactone.

2. The production process according to claim 1, characterized in that: In step S2, the dosage ratio of the soy milk, the Dendrobium officinale residue and the egg white liquid is 100mL:4-8g:10-20mL.

3. The production process according to claim 1, characterized in that: In step S2, the preparation method of the Dendrobium officinale slag is as follows: grinding the dry Dendrobium officinale material, then adding distilled water at a material-water ratio of 1:20-30 for high-pressure extraction, and filtering to obtain the Dendrobium officinale slag and the Dendrobium officinale extract.

4. The production process according to claim 3, characterized in that: The pressure of high-pressure extraction is 0.5-1MPa, the temperature of high-pressure extraction is 80-100°C, and the time of high-pressure extraction is 30-60min.

5. The production process according to claim 1, characterized in that: In step S3, the specific process of heating is: heating at 80-100° C. for 10-30 min.

6. The production process according to claim 1, characterized in that: In step S3, the ratio of the mixed solution to the coagulant is 100 mL: 2-4 g.

7. The production process according to claim 1, characterized in that: In step S3, the mass ratio of the Dendrobium officinale fermentation liquid to glucono-δ-lactone is 10-15:1-2.

8. The production process according to claim 1, characterized in that: In step S3, the preparation method of the Dendrobium officinale fermentation liquid is as follows: inoculating brewer's yeast into the Dendrobium officinale extract, fermenting and culturing, and after the fermentation and culturing is completed, high-temperature sterilization is performed, and the filtrate is filtered and collected to obtain the Dendrobium officinale fermentation liquid.

9. The production process according to claim 8, characterized in that: The fermentation temperature is 28-32° C., the fermentation time is 6-12 hours, and the inoculation amount of brewer's yeast is 1-3% based on the volume of the Dendrobium officinale extract.

10. The tough tofu prepared by the production process according to any one of claims 1 to 9.

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