Processing technology of low-alkali konjac composite gel bean curd
By adding rice flour and chitosan to konjac flour and fermenting and modification, the starch structure is changed, and the taste and shelf life of traditional konjac tofu is solved, and the good molding and water-holding properties of konjac composite gel tofu is achieved. Extend the shelf life and improve the overall quality of the product.
Patent Information
- Application Number
- CN202411634221.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-15
- Publication Date
- 2025-01-03
AI Technical Summary
In the traditional konjac tofu production process, starch granules affect the taste. Too much soda ash is added to cause poor color and harmful to the human body. Insufficient soda ash will make it difficult to form, and the gel product is too soft, prone to water loss, and has a short shelf life.
Add rice flour and chitosan to konjac flour, and change the starch structure in rice through fermentation and modification treatment, increase amylose, form a continuous phase gel grid, reduce the water dispersion loss rate, and use α-acid to inhibit bacterial , reduce the use of alkali and adjust the pH to promote molding and water-holding.
It achieves good molding, water-holding and storage stability of konjac composite gel tofu, extends the shelf life, improves the taste and shelf life, avoids alkaline taste and color problems, and ensures the flavor and elasticity of the product.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of food technology, and in particular to a processing technology of low-alkali konjac composite gel tofu. Background Art
[0002] Konjac is a perennial herb of the Araceae family. It is rich in glucomannan, dietary fiber, etc. and is widely used in the field of weight loss foods. Studies have shown that konjac has the effects of lowering blood lipids, lowering blood sugar, facilitating bowel movements and reducing weight, supplementing calcium, anti-tumor and improving the body's immune function. Konjac flour is obtained from the corm of konjac by physical processing methods. Its main active ingredient is konjac glucomannan, which is a soluble dietary fiber. Konjac has unique physical, chemical and medical value of glucomannan, and konjac tofu is one of its main product forms.
[0003] Konjac tofu has broad application prospects in the field of food and is well received by people. At present, the industrially produced konjac tofu is made of konjac flour as raw material, which is evenly stirred with a certain amount of water to make the konjac flour fully swell into konjac jelly; then, edible alkali is dissolved in a small amount of water, stirred and mixed with the konjac jelly to adjust the pH value of the konjac jelly to be greater than 12, and then placed in a water bath for heating, and then cooled to make konjac tofu; however, konjac contains starchy substances. When the traditional production process is adopted, the particles such as starch will affect the gelation of konjac tofu, and the granularity is heavy when it is eaten cold, which affects the taste; in the traditional production method of konjac tofu, if the amount of soda ash added is large, the color of the finished product is dark brown and the alkaline taste is heavy, and eating too much is likely to cause adverse effects on the human body; if the amount of soda ash added is insufficient, the finished product is not easy to be formed; the konjac tofu made by the traditional process has reduced elasticity at room temperature, is easy to lose water, is not conducive to the taste of the ready-to-eat product, and has the problems of poor coagulation effect, easy damage during the forming process, too soft gel product, relatively sticky in the mouth, short shelf life, etc. Summary of the invention
[0004] The present application provides a processing technology for low-alkali konjac composite gel tofu to solve the technical problems in the prior art.
[0005] In a first aspect, the present application provides a processing technology for low-alkali konjac composite gel tofu, comprising the following steps: S1, washing rice, grinding and drying to obtain rice flour; S2, add 7~25 times of weight of konjac flour into described rice flour, obtain konjac flour mixture after mixing; S3, in described konjac flour mixture, add 3~8% chitosan and 2~6% alpha-acid of its total weight, then add 30~40 times the water of the weight of described konjac flour mixture, mix all with obtaining konjac composite; S4, heating the konjac composite to 80-100° C., heat-expanding for 1-1.5 h, and then cooling at room temperature to obtain konjac composite gel rice tofu.
[0006] Optionally, the rice flour is fermented, specifically comprising the following steps: S1. Wash the rice, add 5-10% yeast by weight, and add tap water until the rice is covered; S2. After sealing, place the rice at 34-40°C for constant temperature fermentation for 15-20 hours; S3, after fermentation is completed, take out the rice, drain the water, and then grind and sieve; S4, vacuum freeze-drying the sifted rice flour to obtain fermented rice flour.
[0007] Optionally, pass the ground rice flour through a 100 mesh sieve.
[0008] Optionally, the fermented rice flour is subjected to a modification process, specifically comprising the following steps: S1, dispersing the fermented rice flour in water to obtain a rice flour dispersion; S2, adding sodium tripolyphosphate to the rice flour dispersion, wherein the sodium tripolyphosphate accounts for 10-16% of the rice flour, and then adjusting the pH of the dispersion to 9 with 1M sodium hydroxide solution, and reacting at 40°C for 1h; S3. After the reaction is completed, the dispersion is cooled and the pH is adjusted to 6 with 1M hydrochloric acid solution, and then centrifuged, washed, and freeze-dried to obtain modified rice flour.
[0009] Optionally, the fermented rice powder has a dispersion concentration of 25 g / L.
[0010] Optionally, after the reaction in step S3 is completed, the dispersion is placed in an ice water bath for cooling.
[0011] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art: The present application provides a processing technology for a low-alkali konjac composite gel tofu. The present invention adds rice flour to konjac flour and adds a corresponding coagulant chitosan to prepare a konjac composite gel tofu, which is easy to shape. However, the addition of rice flour will promote the gel rice tofu to lose water during the later storage process, making its taste worse. Therefore, the rice flour is fermented to change the structure and composition of the starch in the rice, so that the content of amylose in the rice flour is increased, and the amylose can be rapidly polymerized and aged to form a continuous phase gel grid, which buries the slowly aged branched starch and water, reduces the water loss rate, and ensures the taste of the gel rice tofu; and the various organic acids produced during the fermentation process reduce the pH of the gel system, so that the chitosan is dissolved and evenly dispersed in the gel system, and the molding rate is accelerated; at the same time, the fermented rice flour is further modified to further improve the water holding capacity and storage stability of the gel rice tofu; the chitosan promotes the molding of the gel rice tofu, and also synergizes with the α-acid to play an obvious antibacterial effect, so that the gel rice tofu can be stored for a long time without deterioration, and the bitterness of the α-acid itself is masked under the neutralization effect of the rice flour, and the flavor and taste of the gel rice tofu will not be reduced. DETAILED DESCRIPTION
[0012] In one embodiment of the present application, a processing technology of low-alkali konjac composite gel tofu comprises the following steps: S1, washing rice, grinding and drying to obtain rice flour; S2, add 7~25 times of weight of konjac flour into described rice flour, obtain konjac flour mixture after mixing; S3, in described konjac flour mixture, add 3~8% chitosan and 2~6% alpha-acid of its total weight, then add 30~40 times the water of the weight of described konjac flour mixture, mix all with obtaining konjac composite; S4, heating the konjac composite to 80-100° C., heat-expanding for 1-1.5 h, and then cooling at room temperature to obtain konjac composite gel rice tofu.
[0013] In the present application, rice flour and chitosan are added to konjac flour to promote the rapid molding of gel rice tofu, without adding a large amount of alkali to perform molding under the condition of pH greater than 12, and α-acid (Xi'an Tianbao Biotechnology Co., Ltd.) is added at the same time, which acts synergistically with chitosan to achieve a strong antibacterial effect and extend the shelf life of the gel rice tofu.
[0014] As an optional embodiment, the rice flour is fermented, specifically comprising the following steps: S1. Wash the rice, add 5-10% yeast by weight, and add tap water until the rice is covered; S2. After sealing, place the rice at 34-40°C for constant temperature fermentation for 15-20 hours; S3, after fermentation is completed, take out the rice, drain the water, and then grind and sieve; S4, vacuum freeze-drying the sifted rice flour to obtain fermented rice flour.
[0015] In the present application, although the addition of rice flour can promote the rapid molding of gel tofu, the obtained gel tofu is easy to lose water, resulting in poor taste and loss of elasticity of the gel tofu after storage. By fermenting the rice, the structure and composition of the starch in the rice are changed, a continuous phase gel grid is formed in the gel tofu, the slowly aged branched starch and water are buried, the water loss rate is reduced, and the taste and elasticity of the gel tofu are ensured; and a large amount of organic acid is produced during the fermentation process, which reduces the pH value in the gel system, promotes chitosan to play a coagulation and fixation role, and makes the konjac composite gel tofu quickly molded. The yeast is composed of saccharomyces cerevisiae F33 and Pichia kluyveri in a ratio of 1:5 (v / v). During the fermentation process, combined with the limitation of the fermentation process parameters, the structure and composition of the starch in the rice are quickly changed. In the later mixing process with konjac flour, chitosan, etc., the organic acid content in the system can be quickly increased to 34 mol / L, and the later molding efficiency is accelerated to the maximum extent. After molding, the organic acid content is rapidly reduced to avoid affecting the taste of the gel tofu.
[0016] As an optional embodiment, the ground rice flour is passed through a 100-mesh sieve.
[0017] In the present application, the particle size of rice flour is limited to increase its viscosity so that it can quickly form a continuous phase gel grid and improve the water retention effect.
[0018] As an optional embodiment, the fermented rice flour is subjected to a modification treatment, specifically comprising the following steps: S1, dispersing the fermented rice flour in water to obtain a rice flour dispersion; S2, adding sodium tripolyphosphate to the rice flour dispersion, wherein the sodium tripolyphosphate accounts for 10-16% of the rice flour, and then adjusting the pH of the dispersion to 9 with 1M sodium hydroxide solution, and reacting at 40°C for 1h; S3. After the reaction is completed, the dispersion is cooled and the pH is adjusted to 6 with 1M hydrochloric acid solution, and then centrifuged, washed, and freeze-dried to obtain modified rice flour.
[0019] In the present application, although the rice flour can delay the loss of water after fermentation, the effect is unstable. The present invention further modifies the rice flour to improve its stability, so that the gel composite gel tofu can stably maintain the moisture content and maintain a better taste during a longer shelf life.
[0020] As an optional embodiment, the fermented rice powder has a dispersion concentration of 25 g / L.
[0021] In the present application, the dispersion concentration of the fermented rice flour is limited and the degree of modification thereof is controlled so that it can exert stronger stability and improve water holding capacity.
[0022] As an optional implementation, after the reaction in step S3 is completed, the dispersion is placed in an ice water bath for cooling.
[0023] In the present application, rapid cooling in ice water is performed to quickly terminate the reaction and avoid excessive modification, which would affect the shaping effect and water holding effect of the gel rice tofu.
[0024] Example 1 A processing technology for low-alkali konjac composite gel tofu comprises the following steps: S1. Wash the rice, add 5% yeast by weight, and add tap water until the rice is covered; S2, after sealing, place the rice at 34°C for constant temperature fermentation for 15 hours; S3, after fermentation is completed, take out the rice and drain the water, then grind it through a 100-mesh sieve; S4, the sifted rice flour is subjected to vacuum freeze drying to obtain fermented rice flour; S5, the fermented rice flour is dispersed in water at a concentration of 25g / L to obtain a rice flour dispersion; S6, adding sodium tripolyphosphate to the rice flour dispersion, wherein the sodium tripolyphosphate accounts for 10% of the rice flour, and then adjusting the pH of the dispersion to 9 with 1M sodium hydroxide solution, and reacting at 40°C for 1h; S7, after the reaction is completed, the dispersion is placed in an ice-water bath to cool, and the pH is adjusted to 6 with a 1M hydrochloric acid solution, and then centrifuged, washed, and freeze-dried to obtain modified rice flour; S8, add 7 times weight of konjac flour to the modified rice flour, and mix well to obtain a konjac flour mixture; S9, in described konjac flour mixture, add 3% chitosan and 2% alpha-acid of its total weight, then add 30 times the water of the weight of described konjac flour mixture, mix all with obtaining konjac composite; S10, heating the konjac composite material to 80° C., keeping the temperature to expand for 1 hour, and then cooling at room temperature to obtain konjac composite gel rice tofu.
[0025] Example 2 A processing technology for low-alkali konjac composite gel tofu comprises the following steps: S1. Wash the rice, add 7% yeast by weight, and add tap water until the rice is covered; S2, after sealing, place the rice at 38°C for constant temperature fermentation for 17 hours; S3, after fermentation is completed, take out the rice and drain the water, then grind it through a 100-mesh sieve; S4, the sifted rice flour is subjected to vacuum freeze drying to obtain fermented rice flour; S5, the fermented rice flour is dispersed in water at a concentration of 25g / L to obtain a rice flour dispersion; S6, adding sodium tripolyphosphate to the rice flour dispersion, wherein the sodium tripolyphosphate accounts for 14% of the rice flour, and then adjusting the pH of the dispersion to 9 with 1M sodium hydroxide solution, and reacting at 40°C for 1h; S7, after the reaction is completed, the dispersion is placed in an ice-water bath to cool, and the pH is adjusted to 6 with a 1M hydrochloric acid solution, and then centrifuged, washed, and freeze-dried to obtain modified rice flour; S8, adding 19 times weight of konjac flour to the modified rice flour, and mixing to obtain a konjac flour mixture; S9, in described konjac flour mixture, add 7% chitosan and 4% alpha-acid of its total weight, then add 35 times the water of the weight of described konjac flour mixture, mix all with obtaining konjac composite; S10, heating the konjac composite material to 94° C., maintaining the temperature for expansion for 1.3 h, and then cooling at room temperature to obtain konjac composite gel rice tofu.
[0026] Example 3 A processing technology for low-alkali konjac composite gel tofu comprises the following steps: S1. Wash the rice, add 10% yeast by weight, and add tap water until the rice is covered; S2, after sealing, place the rice at 40°C for constant temperature fermentation for 20 hours; S3, after fermentation is completed, take out the rice and drain the water, then grind it through a 100-mesh sieve; S4, the sifted rice flour is subjected to vacuum freeze drying to obtain fermented rice flour; S5, the fermented rice flour is dispersed in water at a concentration of 25g / L to obtain a rice flour dispersion; S6, adding sodium tripolyphosphate to the rice flour dispersion, wherein the sodium tripolyphosphate accounts for 16% of the rice flour, and then adjusting the pH of the dispersion to 9 with 1M sodium hydroxide solution, and reacting at 40°C for 1h; S7, after the reaction is completed, the dispersion is placed in an ice-water bath to cool, and the pH is adjusted to 6 with a 1M hydrochloric acid solution, and then centrifuged, washed, and freeze-dried to obtain modified rice flour; S8, adding 25 times the weight of konjac flour to the modified rice flour, and mixing to obtain a konjac flour mixture; S9, in described konjac flour mixture, add 8% chitosan and 6% alpha-acid of its total weight, then add 40 times the water of the weight of described konjac flour mixture, mix all with obtaining konjac composite; S10, heating the konjac composite material to 100° C., heat-expanding for 1.5 hours, and then cooling at room temperature to obtain konjac composite gel rice tofu.
[0027] Comparative Example 1 Comparing Comparative Example 1 with Example 1, the difference between Comparative Example 1 and Example 1 is that the added rice flour is not fermented or modified.
[0028] Comparative Example 2 Comparing Comparative Example 2 with Example 1, the difference between Comparative Example 2 and Example 1 is that the added rice flour is only subjected to modification treatment.
[0029] Comparative Example 3 Comparing Comparative Example 3 with Example 1, the difference between Comparative Example 3 and Example 1 is that no α-acid is added during the preparation of the konjac composite gel tofu.
[0030] Comparative Example 4 Comparing Comparative Example 4 with Example 1, the difference between Comparative Example 4 and Example 1 is that chitosan is not added during the preparation of the konjac composite gel tofu.
[0031] Related experiments: The konjac composite gel tofu prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to sensory evaluation, and the results are shown in Table 2. Then, the color value was analyzed, and the analysis results are shown in Table 3. The physical properties were analyzed, and the analysis results are shown in Table 4. At the same time, the water holding capacity after storage for 30 days and 60 days was tested, and the shelf life at 5-10°C was measured, and the results are shown in Table 5.
[0032] Sensory Rating: Thirty sensory assessors conducted sensory evaluation on konjac composite gel tofu samples. All participants were familiar with tofu and had experience in sensory evaluation. At the same time, sensory evaluators were trained according to ISO standards before the sensory evaluation to familiarize them with the evaluation system. Samples under the same storage conditions were cut into small cubes of 1 cm×1 cm×1 cm and placed on a white plate. Sensory assessors conducted sensory evaluation from three dimensions: appearance, texture, and flavor.
[0033] Table 1: Sensory scoring criteria: Table 2: Sensory evaluation scores Color value analysis: The color of konjac composite gel tofu was measured according to the International Commission on Illumination (CIE) colorimeter. After calibration with a standard white plate, 3 points were taken for each sample and expressed as L. * Value. * Indicates brightness, ranging from 0 to l00.
[0034] Table 3: Color value test results Physical property analysis: A konjac composite gel tofu sample with a length of 2.5 cm, a width of 2.5 cm, and a height of 2 cm was placed on the sample stage of the texture analyzer. The sample testing parameters were set as pre-test speed 1.0 mm / s, test speed 1.0 mm / s, post-test speed 1.0 mm / s, deformation 30%, and trigger force 5 g.
[0035] Table 4: Physical property analysis data Table 5: Water loss rate and shelf life test data Detailed analysis of Tables 1 to 5: One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages: (1) The gel composite gel tofu prepared by the present invention has good sensory properties, a light yellow appearance, and a distinct luster; a smooth and delicate texture, a dense and uniform organization, a good coagulation state, moderate elasticity, and no defects or cracks; a rich and pure rice flavor without any peculiar smell, and can be loved by the public. The rice tofu prepared in the comparative example has an uneven color, a slightly yellowish white color, and a distinct luster; a rough texture, but a non-dense organization structure.
[0036] (2) The konjac composite gel tofu prepared by the present invention has good water retention and can be stored for a long time without losing water and basically does not age. However, the comparative example has more cases and the ageing is more serious.
[0037] (3) The konjac composite gel tofu prepared by the present invention has a long shelf life and can be stored for a long time without deterioration.
[0038] (4) The konjac composite gel tofu prepared by the present invention has moderate hardness and chewiness, and can be accepted by the majority of consumers.
Claims
1. A processing technology for low-alkali konjac composite gel tofu, characterized in that: The following steps are involved: S1, washing rice, grinding and drying to obtain rice flour; S2, add 7~25 times of weight of konjac flour into described rice flour, obtain konjac flour mixture after mixing; S3, in described konjac flour mixture, add 3~8% chitosan and 2~6% alpha-acid of its total weight, then add 30~40 times the water of the weight of described konjac flour mixture, mix all with obtaining konjac composite; S4, heating the konjac composite to 80-100° C., heat-expanding for 1-1.5 h, and then cooling at room temperature to obtain konjac composite gel rice tofu.
2. The processing technology of a low-alkali konjac composite gel tofu according to claim 1, characterized in that: The rice flour is fermented, which specifically comprises the following steps: S1. Wash the rice, add 5-10% yeast by weight, and add tap water until the rice is covered; S2. After sealing, place the rice at 34-40°C for constant temperature fermentation for 15-20 hours; S3, after fermentation is completed, take out the rice, drain the water, and then grind and sieve; S4, vacuum freeze-drying the sifted rice flour to obtain fermented rice flour.
3. The processing technology of a low-alkali konjac composite gel tofu according to claim 2, characterized in that, The ground rice flour was passed through a 100-mesh sieve.
4. The processing technology of a low-alkali konjac composite gel tofu according to claim 2, characterized in that: The fermented rice flour is subjected to a modification process, which specifically comprises the following steps: S1, dispersing the fermented rice flour in water to obtain a rice flour dispersion; S2, adding sodium tripolyphosphate to the rice flour dispersion, wherein the sodium tripolyphosphate accounts for 10-16% of the rice flour, and then adjusting the pH of the dispersion to 9 with 1M sodium hydroxide solution, and reacting at 40°C for 1h; S3. After the reaction is completed, the dispersion is cooled and the pH is adjusted to 6 with 1M hydrochloric acid solution, and then centrifuged, washed, and freeze-dried to obtain modified rice flour.
5. The processing technology of a low-alkali konjac composite gel tofu according to claim 4, characterized in that: The fermented rice powder dispersion concentration is 25 g / L.
6. The processing technology of a low-alkali konjac composite gel tofu according to claim 4, characterized in that: After the reaction in step S3 is completed, the dispersion is placed in an ice water bath for cooling.