CN103229850B - Common yam rhizome dried bean curd and preparation method thereof - Google Patents

Abstract

The invention discloses a dried bean curd with yam and a preparation method thereof, which comprises the following steps: cleaning and soaking soybeans, adding them to yam juice mixed with yam and water for grinding, filtering, boiling, and Cooling, pulping, heat preservation and solidification, scratching, splashing and draining, pressing, stripping and slicing, marinating, baking, second cooling, vacuum packaging, sterilization, third cooling and final product. As a new variety of bean products, dried tofu with yam not only has unique flavor, fine texture, good quality such as cutting but not falling apart, and high elasticity, but also has good nutritional value and health preservation. Health care has important application value and development prospect.

Description

Dried yam and tofu and preparation method thereof

technical field

The invention belongs to the field of food, and relates to dried yam and tofu and a preparation method thereof.

Background technique

Soybean is rich in protein, fat, vitamins and minerals and other indispensable nutrients in human life activities. Compared with other foods, it has a high protein content and a balanced mix of other nutrients. Soybean lipid also contains 8.7% lecithin. Lecithin can esterify cholesterol under the action of lecithin cholesterol phthalein transferase, transfer it into plasma and excrete it. Therefore, regular consumption of soybean products can lower blood cholesterol and prevent hypertension, arteriosclerosis and cardiovascular diseases. According to reports, soybean fat contains 85.4% unsaturated fatty acids, including linoleic acid, linolenic acid and arachidonic acid. Essential fatty acids account for 52.2% of the total body fat. In addition, compared with other beans and cereals, soybeans are rich in B vitamins and vitamin E; they are also rich in calcium, phosphorus, iron, magnesium, zinc, copper and other minerals and more than 20 kinds of trace elements. More importantly, soybeans contain many physiologically active substances such as soybean saponin, which is a glycoside composed of saponin and sugar. It has hemolytic properties, can reduce cholesterol concentration, inhibit lipid oxidation in serum, and inhibit excessive Oxidized lipid generation; soybean oligosaccharides, which are functional oligosaccharides composed of raffinose, stachyose and sucrose, have the functions of preventing dental caries and regulating the balance of microbial flora in the intestinal tract, promoting bifidobacteria and inhibiting spoilage Effect on bacterial growth; soy isoflavones, which prevent malignant transformation of normal cells. It can be seen that soybean has high nutritional value and health care function. Yam, also known as yam, yam, big potato, foot plantain, Buddha's palm potato, fan potato, is a cultivated species in the genus Dioscorea that can form underground fleshy tubers, and is an annual or perennial winding vine. Yam is a crop with high nutritional value. In addition to water, it also contains various nutrients such as carbohydrates, proteins, minerals, trace elements, vitamins, and amino acids needed by the human body. The moisture content in every 100g tuber is 76.6-82.7g, carbohydrate 14.5-19.4g, protein 1.5-1.9g, crude fiber 0.9g, calcium 19.85mg, phosphorus 42mg, iron 0.3mg, carotene 0.02mg, thiamine 0.08mg , Niacin 0.3mg, riboflavin 0.02mg, ascorbic acid 4mg, and various amino acids. Yam can eliminate cold and heat evil spirits, nourish the middle and benefit energy, grow muscles, and make ears and eyesight after long-term use. Vegetables have more medical value and can be further processed.

At present, yam products are only developed in the field of agricultural products and traditional Chinese medicine products. In this study, soybeans and yams are combined to achieve essential amino acids to complement each other in terms of nutrition, so that the ratio of essential amino acids is closer to the needs of the human body, and the biological value of protein has increased. .

Soybean protein is a substance with great potential and complete functions, which has high research and development value. At present, many scientists in the field of food science at home and abroad are committed to applying high-tech to develop products with different functional properties of soybean protein and apply them in different fields. In recent years, although my country has developed a series of products such as soybean protein isolate, it is mainly limited to the application in meat products. Although it is also used in other foods, the amount of use is very small. Dried tofu is a new type of snack food. Many consumers like it. Dried tofu is a flaky soy product made by pressing soy milk after it has been stewed. Regular consumption of dried tofu can reduce the content of cholesterol in the blood and reduce the chance of arteriosclerosis. The content of inorganic salts such as calcium, iron, and magnesium has been increased, which is more suitable for patients with calcium deficiency. For children, eating dried tofu is beneficial to promote the development of oral chewing function and increase calcium intake. Magnesium is not only beneficial in preventing heart disease, but also helps to improve heart activity. It can significantly improve the digestion and absorption rate of protein. In the process of making dried tofu, heating can destroy the antitrypsin factor in soybeans, thereby improving the digestibility of amino acids. Due to the relationship between processing and various seasonings, people's appetite is increased. Therefore, the development of yam dried tofu not only provides a new method for soybean processing, but also lays the foundation for the processing technology of new varieties of dried tofu.

With the development of society, people's pace of life is accelerating, and traditional dietary products can no longer fully meet the requirements of modern life; Food has great market potential.

Contents of the invention

The technical scheme that the present invention solves the problems of the technologies described above is as follows:

A method for preparing dried yam and tofu, comprising the following steps: washing soybeans, soaking them, adding them to yam juice mixed with yams and water for grinding, filtering, boiling, cooling for the first time, pointing, Insulation and solidification, scratching, splashing and draining, pressing, stripping and slicing, marinating, baking, second cooling, vacuum packaging, sterilization, third cooling and final product.

Further, it is preferred that the yam juice is obtained by the following method: select the yam pieces that have been removed from the beard and roots, dry them, and then crush them, mix the crushed yam powder with water at a ratio of 5% to 20%, and Heat to boiling for 1-2 minutes, then cool and prepare for use.

Further, it is preferred that the soybeans are free from impurities and the pesticide residues comply with national regulations, and soaked for 12 hours after washing.

Further, preferably, in the step of boiling pulp, specifically include:

The raw soybean milk ground and filtered in the refining step is put into a steam sterilizer for heating, the temperature is set at 105° C., and the time is set at 15 minutes.

Further, it is preferable that the pulping step includes: continuously stirring, and stopping pulping when the pulp has sesame-sized particles.

Further, preferably, before the halogenation step, it also includes:

Before marinating, tenderize the dried tofu with 1.0% sodium carbonate solution at 80°C for 4 minutes, then wash the tenderized dried tofu four times with clean water, drain and set aside;

In the halogenation step, comprising:

Prepare the brine with refined salt, diced ginger, cinnamon, soy sauce, green onion, and monosodium glutamate, return the brine to a boil, add dried tofu, cook on high heat for 40 minutes, then change to low heat and cook for 30 minutes, then take it out.

Further, preferably, in the sterilization step, pasteurization is performed for 30 minutes.

Further, it is preferred that in the step of pointing the pulp, the concentration of soybean milk is 1:10, the pH value of the soybean milk is 7.5, the amount of gypsum used as a coagulant for pointing slurry is 0.25%, and the coagulation temperature is 80°C , The solidification time is 35min.

Further, preferably, in the pressing step, the pressing time is 40 minutes.

A dried yam and tofu prepared by the above method.

After the above method is adopted in the present invention, the dried yam tofu prepared by it is a new variety in the ranks of bean products. Compared with the commercially available flavored tofu, it not only has a unique flavor, fine texture, is not loose when cut, and is full of elasticity. Such good quality, while having good nutritional value and health care, has important application value and development prospects.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Description of drawings

The present invention will be described in detail below in conjunction with the accompanying drawings, so as to make the above-mentioned advantages of the present invention clearer. in,

Fig. 1 is the schematic flow sheet of the preparation method of dried yam and tofu of the present invention;

Fig. 2 is a schematic diagram of the influence of medicinal juice addition on the quality of dried tofu;

Fig. 3 is the schematic diagram that the pH of soybean milk affects the quality of dried tofu;

Fig. 4 is a schematic diagram of the influence of the amount of coagulant added on the quality of dried tofu;

Fig. 5 is a schematic diagram of the influence of soymilk concentration on the quality of dried tofu;

Fig. 6 is a schematic diagram of the influence of coagulation temperature on the shaping of dried tofu;

Fig. 7 is a schematic diagram of the influence of coagulation time on the shaping of dried tofu;

Fig. 8 is a schematic diagram showing the effect of pressing time on the shaping of dried tofu.

Detailed ways

The implementation of the present invention will be described in detail below in conjunction with the accompanying drawings and examples, so as to fully understand and implement the process of how to apply technical means to solve technical problems and achieve technical effects in the present invention. It should be noted that, as long as there is no conflict, each embodiment and each feature in each embodiment of the present invention can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

The technical problem to be solved by the present invention is to provide a kind of yam dried bean curd, which is mainly prepared by optimizing the production formula on the basis of the traditional dried bean curd production method combined with modern people's new concept of health.

As shown in Figure 1, it mainly includes:

The soybeans are washed, soaked, and added to the yam juice mixed with yam and water for refining, and then filtered, boiled, cooled for the first time, pulped, heat-preserved and solidified, scratched, splashed and drained, squeezed, and removed Cloth slicing, marinating, baking, second cooling, vacuum packaging, sterilization, third cooling and final product, wherein most of the above-mentioned steps are well known, but the raw materials or some The process conditions are different, and the steps not mentioned in this specification can be completed by existing methods, and will not be described in detail here.

Specifically, in this embodiment, the yam juice is obtained by the following method: select the yam pieces that have been removed from the hair and roots, and then grind them after drying, and mix the crushed yam powder with water at a ratio of 5% to 20%. , and heated to boiling for 1-2min, then cooled and ready for use, wherein, in a preferred embodiment, the ratio is 10%, which has the best effect.

Further, it is preferred that the soybeans are free from impurities and the pesticide residues comply with national regulations, and soaked for 12 hours after washing.

Further, preferably, in the step of boiling pulp, specifically include:

The raw soybean milk ground and filtered in the refining step is put into a steam sterilizer for heating, the temperature is set at 105° C., and the time is set at 15 minutes.

Further, it is preferable that the pulping step includes: continuously stirring, and stopping pulping when the pulp has sesame-sized particles.

Further, preferably, before the halogenation step, it also includes:

Before marinating, tenderize the dried tofu with 1.0% sodium carbonate solution at 80°C for 4 minutes, then wash the tenderized dried tofu four times with clean water, drain and set aside;

In the halogenation step, comprising:

Prepare the brine with refined salt, diced ginger, cinnamon, soy sauce, green onion, and monosodium glutamate, return the brine to a boil, add dried tofu, cook on high heat for 40 minutes, then change to low heat and cook for 30 minutes, then take it out.

Further, preferably, in the sterilization step, pasteurization is performed for 30 minutes.

Further, it is preferred that in the step of pointing the pulp, the concentration of soybean milk is 1:10, the pH value of the soybean milk is 7.5, the amount of gypsum used as a coagulant for pointing slurry is 0.25%, and the coagulation temperature is 80°C , The solidification time is 35min.

Further, preferably, in the pressing step, the pressing time is 40 minutes.

That is to say, the present embodiment determines the optimal formula of the product through the orthogonal test: the concentration of soybean milk is 1:10, the addition amount of yam powder is 10%, the pH value of soybean milk is 7.5, the addition amount of GDL is 0.25%, and the solidification temperature is 80 ℃, the solidification time is 35min, and the pressing time is 40min. Therefore, as a new variety in the ranks of bean products, the dried tofu with yam not only has a unique flavor, fine texture, and is not cut and It has good qualities such as looseness and elasticity, and has good nutritional value and health care. It has important application value and development prospects.

The present embodiment is described in detail below in conjunction with the test, wherein, in the present embodiment, the materials and methods adopted are as follows:

2 Materials and methods

2.1 Materials

2.1.1 Main materials

Soybean (commercially available), yam powder (commercially available), gypsum (CaSO4) (AR), hydrochloric acid (AR), defoamer (AR), sodium carbonate (AR).

2.1.2 Excipients

Refined salt, brown sugar, star anise, cinnamon, fennel, etc. must meet food hygiene standards.

2.1.3 Packaging materials

A transparent retort bag made of nylon/polyvinylidene chloride/polyethylene material.

2.2 Instruments and equipment

The main instruments and equipment are shown in Table 1.

Table 1 Instruments and equipment

Table 1 Instrument and equipment

name model factory Electronic balance MP6001 Nanjing Laibu Technology Industrial Co., Ltd. joyoung induction cooker JYC-21BS1 Shandong Joyoung Small Household Appliances Co., Ltd. Vertical pressure steam sterilizer LD2X-75KBS Shanghai Chuding Analytical Instrument Co., Ltd. Automatic separation refiner LL-35 Hangzhou Saixu Food Machinery Co., Ltd. Precision pH Meter PHS-3C Shanghai Leiyun Test Instrument Manufacturing Co., Ltd. Albert refractometer WAY-2W Beijing Jinkelida Electronic Technology Co., Ltd. Manual Tofu Press JI02801426 Beijing Sanpu Machinery Co., Ltd. Double chamber vacuum packaging machine DTD2500B\2 Jinan Xunjie Machinery Equipment Co., Ltd. Multifunctional Film Sealer DBF-900W Shanghai Chubo Laboratory Equipment Co., Ltd. milk tea insulation bucket H-13L Foshan Shunde Santo Information Technology Co., Ltd. Electric blast drying oven 101A-2 Nantong Tongzhou Ruifeng Pharmaceutical Machinery Co., Ltd.

2.3.2 Main operating points

(1) Preparation of yam juice

Select the yam pieces that have been removed from the hair and roots, and then crush them after drying. Mix the crushed yam powder with water in a certain proportion to prepare yam juice with a concentration of 5%, 10%, 15% and 20%, and heat it to boiling. 1-2min, then cool down and prepare for use.

(2) Raw material handling

Choose soybeans that are free of impurities and whose pesticide residues meet national regulations, and soak overnight (about twelve hours) after washing.

(3) Refining

The soaked soybeans are taken out and put into the prepared yam juice for grinding, and the slag is removed for later use.

(4) boiled pulp

Put the ground raw soybean milk into a steam sterilizer and heat it at a temperature of 105°C for 15 minutes.

(5) Dispensing

Pay attention to uniformity when ordering pulp, and stir frequently, but prevent random stirring. Stop when the slurry has sesame-sized particles.

(6) scratch the brain

The tofu should be shredded before molding. This will not only help to break the network to release the water, but also spread the tofu brain evenly on the cloth. The quality of the produced product is tight, and it can avoid uneven thickness and many gaps.

(7) Squeeze

First spread the wrapping cloth on the template, the four corners of the wrapping cloth should be aligned with the four sides of the iron frame, then put the tofu nao evenly on the cloth, spread the tofu nao evenly with a shovel, so that the tofu nao fills the four sides of the iron frame The corners are enough, and the thickness of each batch should be the same. Pressing should be from light to heavy, gradually increasing the pressure.

(8) marinated

Before marinating, use 80°C, 1.0% sodium carbonate solution to tenderize the dried tofu for 4 minutes, then wash the tenderized dried tofu four times with clean water, drain and set aside. Prepare the brine with refined salt, diced ginger, cinnamon, soy sauce, green onion, and monosodium glutamate, return the brine to a boil, add dried tofu, cook on high heat for 40 minutes, then change to low heat and cook for 30 minutes, then take it out.

(9) Sterilization

Using pasteurization for 30min

2.3.3 Sensory evaluation criteria

2.3.3.1 Sensory evaluation of formula optimization of dried yam and tofu

During the evaluation of sensory quality, an evaluation team composed of 20 professional technicians with experience in sensory evaluation will comprehensively evaluate the sensory quality of the product according to the prescribed scoring standards. The sensory evaluation criteria for dry formula optimization are shown in Table 2.

Table 2 Sensory scoring criteria

Table 2 Organoleptic evaluation results

2.3.3.2 Sensory evaluation criteria for coagulation and molding of dried yam and tofu

During the evaluation of sensory quality, an evaluation team composed of 20 professional technicians with experience in sensory evaluation will comprehensively evaluate the sensory quality of the product according to the prescribed scoring standards. The sensory evaluation criteria for optimization of dry molding process parameters are shown in Table 3.

Table 3 Sensory scoring criteria

Table 3 Organoleptic evaluation results

2.3.4 Single factor test

2.3.4.1 Optimization of the formula of dried yam and tofu

(1) The effect of the amount of yam juice added on the quality of dried tofu

The addition amount of yam juice was 0%, 5%, 10%, 15%, 20% (based on the volume ratio of soybean milk), and the effect of the addition amount of yam juice on the quality of dried tofu was studied.

(2) Effect of pH of soybean milk on the quality of dried tofu

The addition of gypsum was 0.2%, the concentration of soybean milk (ratio of material to water) was 1:10, the solidification time was 40 minutes, the addition of yam juice was 5%, the solidification temperature was 85°C, the pressing time was 40 minutes, and the pH of soybean milk was set to 7.0, 7.5, 8.0, 8.5, 9.0, to study the effect of soymilk pH on the quality of dried tofu.

(3) The effect of the amount of coagulant added on the quality of dried tofu

Soymilk concentration (material-to-water ratio) is 1:10, pH value is 7.0, yam juice addition is 5%, coagulation temperature is 85°C, coagulation time is 40min, pressing time is 40min, coagulant addition amount (g/mL) is respectively Set to 0.20%, 0.25%, 0.30%, 0.35%, 0.45%, to study the effect of coagulant addition on the quality of dried tofu.

(4) Effect of soymilk concentration (material-to-water ratio) on the quality of dried tofu

The addition amount of gypsum is 0.2%, the pH value is 7.0, the addition amount of yam juice is 5%, the coagulation time is 40min, the pressing time is 40min, the coagulation temperature is 85°C, and the concentration of soybean milk (material-water ratio) is set to 1:6, 1: 8. 1:10, 1:12, 1:14, to study the influence of soymilk concentration on the quality of yam and tofu.

2.3.4.2 Optimization of process parameters for forming dried yam and tofu

(1) Effect of solidification temperature on the forming of dried yam and tofu

The coagulation time was 40 minutes, the pressing time was 40 minutes, and the coagulation temperature was set to 75°C, 80°C, 85°C, 90°C, and 95°C, respectively, to study the effect of solidification temperature on the forming of dried yam and tofu.

(2) Effect of solidification time on the molding of dried yam and tofu

The coagulation temperature was 80℃, the pressing time was 40min, and the coagulation time was set to 25min, 30min, 35min, 40min, 45min, respectively, to study the influence of coagulation time on the forming of dried yam and tofu.

(3) Effect of pressing time on the forming of dried yam and tofu

The coagulation temperature was 80℃, the coagulation time was 40min, and the pressing time was set to 25min, 30min, 35min, 40mi, 40min, respectively, to study the effect of pressing time on the forming of dried yam and tofu.

2.3.5 Orthogonal test

2.3.5.1 Orthogonal experiment on formulation optimization of dried yam and tofu

Through a single factor test, four factors were selected: the amount of yam juice added, the concentration of soybean milk (material-to-water ratio), the amount of coagulant added, and the pH of soybean milk. Considering the comprehensive influence of these four factors on the quality of dried tofu, three factors were established for each factor. Level, L9 (34) orthogonal test is carried out to determine the best formulation of the product, and the factor levels of the orthogonal test are shown in Table 4.

Table 4 Orthogonal test factor level table

Table 4 Orthogonal experiment factor levels

2.3.5.2 Orthogonal experiment for optimization of process parameters of dried yam and tofu

On the basis of the formula combination of yam and tofu, different process conditions have a greater impact on the quality of dried tofu. In order to improve the overall quality of yam and tofu, we use the coagulation temperature, coagulation time, and pressing time on the basis of the best formula combination. The influence of these three aspects on the forming of dried yam and tofu optimizes the production process of dried yam and tofu. Three levels were set up for each factor, and the L9(33) orthogonal test was carried out. See Table 5 for the factor levels of the orthogonal test.

Table 5 Orthogonal test factor levels

Table 5 Orthogonal experiment factor levels

2.3.6 Calculation method of yield of dried yam and tofu

(1) Determination of soluble solid content by refractometer method [11].

(2) Calculation of dried tofu yield

Dried tofu yield (%)=W/(M*V)*100%

In the formula: W——tofu dry weight (g)

M——solid content of soybean milk (%)

V - volume of soybean milk (L)

3 Results and Discussion

3.1 Experimental results on formula optimization of dried yam and tofu

3.1.1 Determination of the amount of yam juice added

Yam starch has low degree of polymerization, small molecular weight, high amylopectin content, easy gelatinization, and water-absorbing swelling properties.

Strong and other characteristics have brought great difficulties to production and processing. According to these characteristics of yam in yam powder

The pretreatment and the addition amount of yam powder were tested, so that the taste and sensory quality of the produced dried yam and tofu were improved.

To improve, the results are shown in Figure 1.

It can be seen from Figure 1 that when the addition amount of yam juice is 0% to 5%, the total scores of appearance shape, elasticity and structure of dried tofu are almost the same; especially the scores of flavor and color of dried tofu show a gradual upward trend. When the amount of yam juice added is 5% to 10%, the flavor of dried tofu increases with the increase of yam juice, and the taste is good and unique, and it reaches the highest value at 10%. And when the addition exceeds 10%, it will have a greater impact on the quality of dried tofu, with rough surface, unattractive appearance, loose tissue and shapeless, sticky teeth, and poor bite strength. From the analysis of the comprehensive sensory score, the dried bean curd obtained with the addition of yam juice below 10% has good elasticity and toughness, small and uniform internal tissue pores, chewy, soft and refreshing, and has the unique fragrance and sweetness of yam.

3.1.2 Effect of pH of soymilk on quality of dried tofu

The addition of gypsum was 0.2%, the concentration of soybean milk (ratio of material to water) was 1:10, the solidification time was 40 minutes, the addition of yam juice was 5%, the solidification temperature was 85°C, the pressing time was 40 minutes, and the pH of soybean milk was set to 7.0, 7.5, 8.0, 8.5, 9.0, the effect of soymilk pH on the quality of dried tofu is shown in Figure 2.

Analysis of Figure 2 shows that as the pH of soy milk increases, the total scores of appearance, shape, elasticity, structure, and flavor of dried tofu increase significantly, but when the pH of soy milk reaches 9.0, the color, elasticity, structure, and flavor of dried tofu are all obvious decline.

3.1.3 The effect of the amount of coagulant added on the quality of dried tofu

Soymilk concentration (material-to-water ratio) is 1:10, pH value is 7.0, yam juice addition is 5%, coagulation temperature is 85°C, coagulation time is 40min, pressing time is 40min, coagulant addition amount (g/mL) is respectively The settings are 0.20%, 0.25%, 0.30%, 0.35%, 0.45%, and the effect of coagulant addition on the quality of dried tofu is shown in Figure 3.

Analysis of Figure 3 shows that when the amount of coagulant added is 0.20%, the internal tissue pores of dried tofu are not evenly distributed. When the amount of coagulant added was 0.25%, the elasticity of dried yam and tofu increased obviously, and the internal tissue pores became smaller, and the chewiness of dried tofu became better and better, and the elasticity was the best when the amount of coagulant added was 0.30%.

3.1.4 Effect of soymilk concentration (material-to-water ratio) on the quality of dried tofu

The addition amount of gypsum is 0.2%, the pH value is 7.0, the addition amount of yam juice is 5%, the coagulation time is 40min, the pressing time is 40min, the coagulation temperature is 85°C, and the concentration of soybean milk (material-water ratio) is set to 1:6, 1: 8. 1:10, 1:12, 1:14, the effect of soymilk concentration (material-to-water ratio) on the quality of dried yam and tofu is shown in Figure 4.

Analysis of Figure 4 shows that when the concentration of soybean milk (ratio of material to water) is 1:8, the elasticity of dried yam and tofu increases, and the elasticity is the best when the concentration of soybean milk (ratio of material to water) is 1:10. When the concentration of soy milk (ratio of material to water) continued to increase, the elasticity of dried tofu remained stable and did not change significantly. When the concentration of soybean milk (ratio of material and water) is higher than 1:10, the shape, structure, flavor and color of dried yam and tofu have no obvious changes. Therefore, the concentration of soybean milk (ratio of material to water) was selected as 1:6, 1:8, 1:10 for orthogonal experiment.

3.2 Orthogonal test results of formula optimization of dried yam and tofu

Through a single factor test, four factors were selected: the amount of yam juice added, the concentration of raw soybean milk, the amount of coagulant added, and the pH of soybean milk. Considering the comprehensive influence of these four factors on the quality of dried yam and tofu, the optimal range of addition was established for each factor 3 levels of L9(34) orthogonal test is carried out to determine the optimal formulation of the product, and the results of the orthogonal test are shown in Table 6.

Table 6 Orthogonal test results of formula optimization of dried yam and tofu

Table 6 yam bean curd recipe optimization of results of orthogonal test

From the results of the orthogonal test in Table 6, it can be seen that the optimal level of the production formula of dried yam and tofu is A2B1C2D3. The factors affecting the quality of dried yam and tofu were A>D>B>C, that is, the concentration of yam juice had the greatest influence, followed by the concentration of raw soybean milk, and the addition of coagulant had the least influence. The best formula combination of dried yam and tofu is 10% of yam juice, 7.5 pH of soybean milk, 0.25% of coagulant, and 1:10 concentration of soybean milk (material-to-water ratio).

3.3 Experimental results of optimization of process parameters for yam dried bean curd

3.3.1 Effect of solidification temperature on the molding of dried yam and tofu

On the basis of the optimal formula combination of dried yam and tofu, the solidification temperature was set to 75°C, 80°C, 85°C, 90°C, and 95°C, respectively.

Analysis of Figure 5 shows that when the solidification temperature rises to 80°C, the sensory score of the dried yam and tofu begins to increase. When the solidification temperature reaches 85°C, the dried yam and tofu form the best shape, with less fragments and good elasticity. At ℃, the sensory score of dried yam and tofu began to decrease, and the dried yam and tofu had poor elasticity, many fragments, and sticky. Therefore, 80°C, 85°C, and 90°C were selected for the coagulation temperature to carry out the orthogonal test.

3.3.2 Effect of solidification time on the molding of dried yam and tofu

On the basis of the best formula combination of dried yam and tofu, set the setting time to 25min, 30min, 35min, 40min, and 45min respectively, and the results of the research on the effect of setting time on the formation of dried yam and tofu are shown in Figure 6.

Analysis of Figure 6 shows that when the solidification time reaches 30 minutes, the forming sensory score of dried yam and tofu begins to increase, the elasticity of dried yam and tofu increases, and the fragments decrease. Well, with the increase of time, the elasticity of dried yam and tofu becomes smaller, and the fragments increase. Therefore, the setting time is selected as 30min, 35min, and 40min for orthogonal experiments.

3.3.3 Effect of pressing time on the molding of dried yam and tofu

On the basis of the optimal formula combination of dried yam and tofu, the pressing time was set to 25min, 30min, 35min, 40min, and 45min respectively.

Analysis of Figure 7 shows that when the pressing time reaches 35 minutes, the forming sensory score of dried yam and tofu begins to increase, the elasticity of dried yam and tofu increases, and the fragments decrease. When the pressing time is 40 minutes, the dried yam and tofu have the best elasticity, the least fragments, and the sliceability Well, with the increase of time, the elasticity of dried yam and tofu becomes smaller, the fragments increase, and the thickness is uneven. Therefore, the pressing time is selected as 30min, 35min, and 40min for orthogonal experiments.

3.4 Orthogonal test results affecting the molding of dried yam and tofu

The coagulation temperature, coagulation time, and pressing time were selected as the main parameters affecting the molding process of dried yam and tofu, and an orthogonal experiment of 3 levels and 3 factors L9 (33) was carried out. The results of the experiment are shown in Table 7.

Table 7 Orthogonal test results affecting the molding of dried yam and tofu

Table 7 Yam bean curd forming the orthogonal test results

From the results of the orthogonal test in Table 7, it can be seen that the optimal level of the production process of dried yam and tofu is A2B2C3. The factors affecting the yield of dried yam and tofu were C>B>A, that is, the pressing time had the greatest influence, followed by the solidification time, and the solidification temperature had the least influence. Therefore, it is concluded that the optimal production process of dried yam and tofu is 80°C coagulation temperature, 35 min coagulation time and 40 min pressing time.

3.6 Discussion

(1) At present, there are only a few types of yam products in the market. Most of the functional health foods developed from yam are dairy products and solid beverages. The development of yam dried tofu not only increases the variety of yam health food, but also provides a new method for the deep processing of yam.

(2) Due to the high starch content of yam, the characteristics of water absorption and easy expansion have a certain impact on the molding of yam and tofu, the coagulant used in this study is gypsum, and the taste of yam and tofu made with gypsum is more delicate. The softness and hardness are moderate, which is conducive to the forming of dried yam and tofu.

4 Conclusion

In this paper, the optimal formula of yam and tofu is determined through experiments: the addition of yam juice is 10%, the pH of soybean milk is 7.5, the addition of coagulant is 0.25%, the concentration of soybean milk (material-water ratio) is 1:10, and the defoamer after refining The amount of addition is 0.15% to 0.20% of the volume of the ingredients.

The optimal process is the coagulation temperature of 85°C, the coagulation time of 35 minutes, and the pressing time of 40 minutes. The dried yam and tofu prepared under this process condition is light yellow, bright in color, smooth in skin, fine and uniform in pores, high in elasticity, fast in rebound, refreshing in taste and non-sticky to teeth. With the improvement of people's living standards, diets have shifted from a subsistence type to a functional type. As a high-nutrition health care, therapeutic food is more and more valued by people. Therefore, the development of health-care type yam dried tofu has broad market prospects.

It should be noted that, for the above method embodiments, for the sake of simple description, they are expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the described action sequence. Depending on the application, certain steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification belong to preferred embodiments, and the actions and modules involved are not necessarily required by this application.

Finally, it should be noted that: the above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, it still The technical solutions recorded in the foregoing embodiments may be modified, or some technical features thereof may be equivalently replaced. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (4)

1. The preparation method of the yam dried tofu is characterized by comprising the following steps: cleaning and soaking soybeans, adding yam juice mixed by yam and water into the soybeans, grinding the mixture into thick liquid, filtering, boiling the thick liquid, cooling for the first time, curdling, insulating and solidifying, scratching the brain, splashing slices, draining, squeezing, removing cloth, slicing, marinating, baking, cooling for the second time, vacuum packaging, sterilizing, cooling for the third time and obtaining a finished product;

the step of boiling the soybean milk specifically comprises the following steps:

heating the raw soybean milk which is ground in the step of grinding and filtered in a steam sterilizer at 105 ℃ for 15 min;

the slurry curdling step comprises the following steps: continuously stirring, and stopping curdling when sesame-sized particles appear in the slurry; the Chinese yam juice is obtained by the following method: selecting Chinese yam blocks without beard and root, drying, sieving, crushing, mixing the crushed Chinese yam powder with water in a proportion of 5-20%, heating to boil for 1-2min, and cooling for later use; selecting soybeans which are free of impurities and have pesticide residues meeting national regulations, cleaning the soybeans, and soaking the soybeans for twelve hours; before the step of marinating, the method further comprises the following steps:

tenderizing dried bean curd with sodium carbonate solution with concentration of 1.0% at 80 deg.C for 4min before marinating, cleaning the tenderized dried bean curd with clear water for four times, and draining;

the marinating step comprises the following steps:

mixing bittern with refined salt, diced ginger, cassia bark, soy sauce, shallot and monosodium glutamate, boiling the prepared bittern in a pot, adding dried bean curd, boiling with strong fire for 40min, boiling with soft fire for 30min, and taking out;

in the curdling step, the concentration of the soybean milk is 1: 10, the pH value of the soybean milk is 7.5, the addition amount of gypsum used as a coagulant for curdling is 0.25%, the coagulation temperature is 80 ℃, and the coagulation time is 35 min.

2. The method for preparing the yam dried tofu according to claim 1, wherein in the step of sterilization, pasteurization is carried out for 30 min.

3. The preparation method of the yam dried tofu according to claim 1, wherein in the pressing step, the pressing time is 40 min.

4. A yam dried tofu prepared by the method of any one of claims 1 to 3.