A perilla beancurd skin and a preparation method thereof

Abstract

The present application provides a perilla tofu skin and a preparation method thereof, and belongs to the field of food processing. The problems of single nutritional components, single taste and low alpha-linolenic acid content of the existing tofu skin are solved. A perilla tofu skin is prepared from the following raw materials by weight: 30-90 parts of soybeans and 10-50 parts of perilla seeds. The perilla tofu skin is mainly used as food.

Description

Technical Field

[0001] This invention belongs to the field of food processing, and in particular relates to a perilla-flavored dried bean curd stick and its preparation method. Background Technology

[0002] Tofu skin (yuba) is a traditional Chinese soy product made primarily from soybeans. It undergoes processes such as soaking, grinding, boiling, peeling, and drying. It is popular among consumers due to its high protein content, chewy texture, and rich nutritional value. Protein is an essential nutrient for the human body and a fundamental building block of human cells. According to the protein reference intake set by the Chinese Nutrition Society in 2026, adults need to consume 60-80 grams of protein daily. Soy protein, as a complete protein, contains all eight essential amino acids required by the human body and is an important source of high-quality protein in the daily diet of Chinese residents.

[0003] α-Linolenic acid (C 18 H 30 O2 (all-cis-9,12,15-octadecanoic acid, ALA) is an essential omega-3 polyunsaturated fatty acid that the human body cannot synthesize and must obtain through daily diet. In the body, it can be converted into active metabolites such as EPA and DHA. Numerous studies have confirmed that alpha-linolenic acid helps regulate blood lipids, reduce blood viscosity, and maintain vascular elasticity, playing a positive role in preventing cardiovascular disease. Simultaneously, as an important structural component of the nervous system, it is also crucial for brain development, vision, and the maintenance of cognitive function.

[0004] Perilla seeds have a high fat content of 40%–50%, of which α-linolenic acid accounts for about 50%–60%, making it the most representative functional component of the seed. In addition, they contain 18%–25% high-quality protein, with high levels of essential amino acids such as lysine and arginine, further enhancing their nutritional value as a plant-based functional food ingredient.

[0005] Therefore, developing perilla-flavored dried bean curd rich in α-linolenic acid to improve its nutritional value while maintaining its good flavor is of great application value. Summary of the Invention

[0006] In view of this, the present invention aims to propose a perilla-flavored dried bean curd stick and its preparation method to solve the problems of existing dried bean curd sticks having poor nutritional composition, monotonous flavor, and low α-linolenic acid content.

[0007] To achieve the above objective, according to a first aspect of the present invention, a perilla-flavored dried bean curd stick is provided, which is made from the following raw materials in parts by weight: 30-90 parts soybeans and 10-50 parts perilla seeds.

[0008] Furthermore, the perilla-flavored dried bean curd is made from the following ingredients in parts by weight: 50 parts soybeans and 20 parts perilla seeds.

[0009] According to a second aspect of the present invention, a method for preparing perilla-flavored dried bean curd is provided, comprising the following steps:

[0010] S1. Weigh the perilla seeds by weight, remove impurities and clean them, and stir-fry them at a preset temperature for a certain time.

[0011] S2, weigh soybeans according to weight, remove impurities and clean them, and perform enzymatic hydrolysis on the soybeans;

[0012] S3, mix the roasted perilla seeds with water at a mass ratio of 1:3, grind and filter to obtain perilla pulp; mix the enzymatically hydrolyzed soybeans with water at a mass ratio of 1:5, grind and filter to obtain soybean pulp;

[0013] S4. Boil the soybean milk for a preset time, then mix it with room temperature perilla milk. The soybean milk and perilla milk are mixed at a volume ratio of 1:1 to 5:1 and stirred evenly to obtain a mixed slurry.

[0014] S5, after the mixed slurry is peeled off and dried, the perilla dried bean curd product is obtained.

[0015] Furthermore, the perilla seeds are prepared by stir-frying at 75°C for 15 minutes.

[0016] Furthermore, the enzymatic hydrolysis method is as follows: add 0.5% by weight of cellulase and 0.3% by weight of pectinase to the soybeans, adjust the pH to 6.5, and hydrolyze at a constant temperature of 45°C for 1-3 hours; after rinsing with clean water, soak the soybeans in 40°C warm water for another 10 hours.

[0017] Furthermore, the pulping conditions are pulping for 30 minutes using a pulper at 2500 rpm.

[0018] Furthermore, in step S5, the soybeans are boiled at 100°C for 40 minutes.

[0019] Furthermore, in step S6, the method of removing the film is as follows: the mixed slurry is transferred into the bean curd peeling mold, the temperature is controlled at 90°C, and it is kept warm and left to stand. After a thin film is formed on the surface, it is peeled off, placed in a preset position, and the surface moisture is drained to obtain the initial product of perilla bean curd.

[0020] Furthermore, in step S6, the drying method is as follows: first-stage drying, with the hot air temperature set at 80℃ and the air velocity at 25m. 3 Drying time is 1-2 hours per second; for the second stage of drying, the hot air temperature is set to 55℃ and the air velocity is 25m / s. 3 Dry for 16-20 hours, until the moisture content of the perilla-flavored dried bean curd is below 5%.

[0021] Furthermore, after the perilla-flavored dried bean curd products have completely cooled and rehydrated, they are cut into preset lengths and packaged.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. This perilla-flavored tofu skin is the first product to introduce perilla seeds into the traditional tofu skin processing system, developing a new type of composite tofu skin product that combines the characteristic aroma of perilla with the texture of tofu skin. It also develops a new technology for the co-processing of functional oils from plant sources and soy products, enriching the product category structure of tofu skin.

[0024] 2. This method for preparing perilla-flavored tofu skin involves moderately roasting perilla seeds to fully release their characteristic aroma components, which then harmonize and blend with the pure bean aroma of traditional tofu skin. This gives the product a new flavor that is rich in layers and highly recognizable, meeting consumers' demand for functional and distinctive food products. Perilla-flavored tofu skin has been comprehensively improved in terms of both taste and nutrition.

[0025] 3. The α-linolenic acid content in the perilla-flavored tofu skin produced by this method reaches 21.3% of the total fatty acids, which is significantly higher than the approximately 3% content in ordinary tofu skin. At the same time, the volatile oils, flavonoids, anthocyanins and other bioactive components rich in perilla seeds are retained during processing, so that the product not only provides high-quality plant protein, but also has the synergistic effect of multiple functional factors, significantly improving its nutritional value and meeting the modern consumer preference for natural, healthy and functional foods.

[0026] 4. This product organically combines the easily digestible and absorbable properties of dried bean curd sticks with the physiological activity of perilla, forming a soy product that has both nutritional supplementation and daily health care functions. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 This is a finished product image of the perilla-flavored dried bean curd sticks described in this invention;

[0029] Figure 2 This is a flowchart of the method for preparing perilla-flavored dried bean curd according to the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0031] It should be noted that the descriptions of "left," "right," "left side," "right side," "upper part," "lower part," "top," and "bottom" in this invention are defined based on the orientation or positional relationships shown in the accompanying drawings. They are merely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the described structure must be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] In the description of this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Referring to the accompanying drawings, this embodiment describes a type of perilla-flavored dried bean curd made from the following raw materials in parts by weight:

[0034] 30-90 parts soybeans, 10-50 parts perilla seeds. Preferably, it is made from the following raw materials in parts by weight: 50 parts soybeans, 20 parts perilla seeds. The specific preparation method is as follows:

[0035] Step 1, Perilla seed pretreatment:

[0036] Select plump and uniformly sized perilla seeds, remove impurities, and wash them thoroughly. The perilla seeds need to be roasted at 75℃ for 15 minutes to enhance their aroma and increase the oil extraction rate. The roasting temperature and time can be adjusted according to the material properties and state of the product. Any roasting method that can enhance the aroma of the perilla seeds and increase the oil extraction rate can be used in this application and is within the spirit of the invention. Without the roasting process, the aroma of the resulting perilla-flavored dried bean curd is reduced, and the yield of the product with the same raw material ratio decreases by approximately 3% to 7%.

[0037] Step 2, Soybean Pretreatment:

[0038] Select plump, mold-free soybeans, remove impurities, and wash them thoroughly. To improve the yield of soybean milk and reduce the beany taste, the soybeans undergo enzymatic hydrolysis: add 0.5% (by weight) of cellulase and 0.3% (by weight) of pectinase, adjust the pH to 6.5, and hydrolyze at a constant temperature of 45℃ for 1-3 hours; after rinsing with water, soak the soybeans in 40℃ warm water for another 10 hours. The dosage of cellulase and pectinase can be adjusted according to the variety and characteristics of the soybeans.

[0039] Step 3, grinding:

[0040] Perilla seeds and water were mixed at a mass ratio of 1:3 (w / w), and the mixture was ground in a pulper at a speed of 2500 rpm for 30 minutes to obtain perilla pulp.

[0041] Soaked soybeans are mixed with water at a mass ratio of 1:5 (w / w) and ground in a pulping machine at 2500 rpm for 30 minutes to obtain soybean milk.

[0042] Step 4, Filtering:

[0043] The mixture of perilla syrup and soybean syrup was filtered separately to remove solid residue, resulting in two different slurries.

[0044] Step 5, Mix:

[0045] Soybean milk is boiled at 100℃ for 40 minutes, then mixed with room-temperature perilla milk. A soybean milk to perilla milk volume ratio of 5:1 to 1:1 can achieve film formation and peeling, but the film-forming speed decreases as the proportion of perilla milk increases. Therefore, considering both product nutrition and production efficiency, a soybean milk to perilla milk volume ratio of 3:1 is chosen. Furthermore, the critical control point in perilla milk production is the cold perilla milk being injected into hot soybean milk. Research has shown that injecting heated perilla milk into hot soybean milk interferes with film formation in the tofu skin, and the α-linolenic acid content in the finished product also decreases. This reduces both the overall process efficiency and the product's nutritional content. Therefore, cold-hot mixing is a necessary prerequisite for preserving nutritional characteristics and processing efficiency.

[0046] Step 6, Peeling and Shaping

[0047] Transfer the perilla and soybean mixture into the tofu skin peeling pot, control the temperature at 90℃, keep it warm and let it stand. After a thin film forms on the surface, peel it off, place it on a 316 stainless steel pipe, and drain the surface water to obtain the initial product of perilla tofu skin.

[0048] Step 7, Drying:

[0049] The initial product of perilla-flavored dried bean curd is sent to a drying room for dehydration. The first stage of drying in the drying room is carried out with a hot air temperature of 80℃ and an air velocity of 25m. 3 Dry for 1-2 hours at a speed of 1 / s; after removing most of the moisture, proceed to the second stage of drying, with the hot air temperature set at 55℃ and the air velocity at 25m / s. 3 Dry at 16-20 h per s until the moisture content of the perilla-flavored dried bean curd is below 5%. The two-stage drying method has a lower overall drying temperature, which can effectively protect the activity of α-linolenic acid in perilla and improve the drying efficiency of perilla-flavored dried bean curd.

[0050] Step 8, Packaging:

[0051] After the dried perilla bean curd sticks have completely cooled and regained moisture, they are sent to a cutting machine to be shaped to a suitable length. They are then weighed and packaged according to sales requirements to obtain the finished perilla bean curd sticks.

[0052] The film formation of dried bean curd sticks is essentially a process where, during the continuous heating of soy milk, protein molecules denature and unfold, cross-linking through forces such as disulfide bonds to form a three-dimensional gel network. Simultaneously, this network encapsulates and enriches fat droplets dispersed in the slurry, ultimately forming a protein-lipid composite film with specific mechanical strength at the gas-liquid interface. This process is extremely sensitive to the degree of protein denaturation, the protein-to-fat ratio, and their interaction states in the slurry. The technical challenge of introducing perilla into the dried bean curd stick system lies precisely in this. If perilla oil is added directly to the soy milk, the free oil cannot effectively bind with the protein, disrupting the foundation for the formation of the protein-lipid composite film, leading to difficulty in peeling or easy film breakage. To effectively integrate perilla into the protein network of dried bean curd sticks, two key breakthroughs are needed: first, moderate roasting to achieve a synergistic dissolution of proteins and oils in the perilla seeds; second, using a "cold slurry injected into hot soy milk" method to prevent premature thermal denaturation of the perilla components, which would interfere with the normal cross-linking of soy proteins. The above operating conditions were determined based on a systematic analysis of the film-forming mechanism of dried bean curd sticks and long-term process exploration, and were achieved through repeated trial and error and parameter optimization.

[0053] The prepared perilla-flavored dried bean curd is a natural antioxidant and functional food. A 500g sample was tested, and the data showed that this product has significant advantages in terms of nutritional components and sensory quality.

[0054] It not only possesses high protein (43.5g / 100g as tested by GB5009.5-2025 Method I), high α-linolenic acid (21.3% as tested by GB5009.168-2016 Method III), but also high potassium (1.25×10⁻⁶ as tested by GB5009.91-2017 Method I). 3 It boasts nutritional characteristics of being low in sodium (272 mg / 100g, as measured by GB5009.91-2017 Method I), and also possesses excellent texture with a bright color and good elasticity. It also has the aroma of soybeans and roasted perilla seeds, resulting in a product with rich layers and high recognizability.

[0055] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A type of perilla-flavored dried bean curd, characterized in that: The perilla-flavored dried bean curd sticks are made from the following raw materials in parts by weight: 30-90 parts soybeans, 10-50 parts perilla seeds.

2. The perilla-flavored dried bean curd sticks according to claim 1, characterized in that: The perilla-flavored dried bean curd is made from the following ingredients in parts by weight: 50 parts soybeans and 20 parts perilla seeds.

3. A method for preparing perilla-flavored dried bean curd sticks according to any one of claims 1-2, characterized in that, Includes the following steps: S1. Weigh the perilla seeds by weight, remove impurities and clean them, and stir-fry them at a preset temperature for a certain time. S2, weigh soybeans according to weight, remove impurities and clean them, and perform enzymatic hydrolysis on the soybeans; S3, mix the roasted perilla seeds with water at a mass ratio of 1:3, grind and filter to obtain perilla pulp; mix the enzymatically hydrolyzed soybeans with water at a mass ratio of 1:5, grind and filter to obtain soybean pulp; S4. Boil the soybean milk for a preset time, then mix it with room temperature perilla milk. The soybean milk and perilla milk are mixed at a volume ratio of 1:1 to 5:1 and stirred evenly to obtain a mixed slurry. S5, after the mixed slurry is peeled off and dried, the perilla dried bean curd product is obtained.

4. The preparation method according to claim 3, characterized in that, The perilla seeds are prepared by stir-frying at 75℃ for 15 minutes.

5. The preparation method according to claim 3, characterized in that, The enzymatic hydrolysis method is as follows: add 0.5% cellulase and 0.3% pectinase by weight of soybeans, adjust the pH to 6.5, and enzymatically hydrolyze at a constant temperature of 45 ℃ for 1-3 hours; after rinsing with clean water, soak the soybeans in 40 ℃ warm water for another 10 hours.

6. The preparation method according to claim 3, characterized in that: The grinding conditions were: grinding with a pulper at 2500 rpm for 30 minutes.

7. The preparation method according to claim 3, characterized in that: In step S5, the soybeans are boiled at 100 ℃ for 40 minutes.

8. The preparation method according to claim 3, characterized in that, In step S6, the method of removing the film is as follows: the mixed slurry is transferred into the tofu skin removal mold, the temperature is controlled at 90°C, and it is kept warm and left to stand. After a thin film is formed on the surface, it is peeled off, placed in a preset position, and the surface moisture is drained to obtain the initial product of perilla tofu skin.

9. The preparation method according to claim 8, characterized in that, In step S6, the drying method is as follows: first-stage drying, with hot air temperature set at 80 ℃ and air velocity at 25 m / s. 3 Drying time is 1-2 hours per second; for the second stage of drying, the hot air temperature is set to 55℃ and the air velocity is 25m / s. 3 Dry for 16-20 hours, until the moisture content of the perilla-flavored dried bean curd is below 5%.

10. The preparation method according to claim 3, characterized in that: After the perilla-flavored dried bean curd products have completely cooled and rehydrated, they are cut into preset lengths and packaged.

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