A rice cake rich in auricularia auricular polysaccharide and a preparation method thereof

Abstract

This invention provides a rice cake rich in black fungus polysaccharides and its preparation method. The steps are as follows: S1. Crushed rice is sieved and mixed with natural polysaccharide excipients to form a slurry, which is then dried to obtain rice starch aerogel microspheres; S2. The slurry is fermented with Bacillus subtilis, rinsed, and dried to obtain microbially modified aerogel microspheres; S3. A cellulose nanofiber dispersion is prepared; S4. The dispersion is mixed with refrigerated egg white, stirred, and whipped to obtain nanofiber-reinforced egg white foam; S5. The modified aerogel microspheres and black fungus polysaccharides are added to the rice slurry and mixed evenly; S6. The mixture is gently folded with the egg white foam, extruded, and baked and cooled to obtain the finished product. This invention forms a closed loop through the physical anti-sticking properties of the aerogel microcarrier and the bio-toughening effect of the dual microbial network, ensuring molding and structural stability. The nanofiber-reinforced foam structure and the porous structure of the aerogel work synergistically to promote rapid moisture evaporation and improve crispness, while simultaneously encapsulating the black fungus polysaccharides to prevent high-temperature denaturation, ultimately achieving comprehensive optimization of product performance.

Description

Technical Field

[0001] This invention belongs to the field of functional (leisure) food processing technology, specifically relating to a rice cake rich in black fungus polysaccharides and its preparation method. Background Technology

[0002] Rice cakes are a type of snack food made from rice as the core ingredient, refined through processes such as puffing and baking. Their crisp texture, rich rice aroma, and convenient consumption make them popular with consumers. With the upgrading of consumption and the popularization of health concepts, low-sugar, low-fat, and nutritionally functional products have become the mainstream market trend, driving the rice cake industry to transform from traditional flavors to a high-quality development stage of "health + specialty." my country's rice cake market has shown strong growth potential and broad development space. Numerous experts and scholars have delved into this field, developing a variety of rice cake products that combine health attributes with distinctive flavors through scientific formulation, process innovation, and sensory evaluation technology, continuously injecting innovative vitality into the industry.

[0003] Broken rice, a byproduct of rice processing, accounts for 8% to 12% of total rice production. Although its morphological defects make it unsuitable as a staple food, it contains abundant starch resources and possesses significant utilization value. Through modern food processing innovation, broken rice can replace some whole rice in rice cake production, achieving efficient resource conversion: its starch properties, through puffing and baking processes, can impart a crisp texture and rich rice aroma to rice cakes, while reducing raw material costs and minimizing food waste. However, broken rice presents significant technical challenges during processing—its high free starch content makes it prone to sticking during extrusion molding and baking, leading to equipment adhesion, incomplete product shaping, and uneven texture, severely impacting production efficiency and product stability. Although existing technologies attempt to improve this through adjusting proportions and optimizing extrusion parameters, these methods are mostly single-dimensional controls and fail to fundamentally solve the core problem of broken rice sticking, limiting its large-scale application in rice cake production. Furthermore, traditional rice cake products primarily offer basic flavor and texture, lacking sufficient functional attributes and failing to meet consumers' higher-level demands for health and nutrition.

[0004] Black fungus polysaccharide is an acidic heteropolysaccharide extracted from black fungus. It is mainly composed of monosaccharides such as glucose, mannose, and xylose, and possesses various biological activities including hypoglycemic, hypolipidemic, antioxidant, immunomodulatory, and antithrombotic effects. Modern research shows that black fungus polysaccharide can significantly inhibit the activity of α-glucosidase and α-amylase, scavenge free radicals, and improve glucose and lipid metabolism by regulating intestinal flora and resisting oxidative stress. Its high nutritional value and pharmacological effects have been widely confirmed. Introducing black fungus polysaccharide into rice cake products can not only enrich the nutritional functions of rice cakes but also align with the trend of low-sugar and low-fat healthy consumption, providing a new direction for the upgrading of the rice cake industry. However, black fungus polysaccharides are easily affected by high temperature and mechanical shearing during food processing, leading to loss of activity. Furthermore, their addition may further alter the rheological properties of the raw material system, bringing uncertain effects on the molding stability and sensory quality of rice cakes. At the same time, the egg white foam structure commonly used in existing rice cake preparation is prone to defoaming and collapse during processing, resulting in uneven porous structure and poor taste in the product. These problems have not been effectively solved.

[0005] Based on this, overcoming the above challenges and developing a flavored rice cake with black fungus polysaccharide and broken rice as the main ingredients can promote the upgrading of deep processing of grain towards high added value, sustainability and functionality, and has important economic and social benefits. Summary of the Invention

[0006] Technical problem to be solved: In view of the above problems, the purpose of this invention is to provide a rice cake rich in black fungus polysaccharide and its preparation method. By forming a closed loop through the physical anti-sticking of aerogel microcarrier and the bio-toughening of the dual microbial network, the molding and structural stability are guaranteed. The foam structure reinforced by nanofibers and the porous structure of aerogel work together to promote rapid evaporation of moisture and improve crispness. At the same time, the black fungus polysaccharide is encapsulated to avoid high temperature denaturation, and finally the product performance is optimized in all aspects.

[0007] Technical solution: A method for preparing rice cakes rich in black fungus polysaccharides, comprising the following steps: S1. After crushing broken rice and passing it through an 80-100 mesh sieve, mix it with natural polysaccharide excipients, add deionized water to make a homogeneous slurry, and then freeze-dry and supercritical drying to prepare broken rice starch aerogel microspheres. S2. Place broken rice starch aerogel microspheres in a Bacillus subtilis fermentation system and ferment at 30-37℃ and pH 6.5-7.5 for 48-72 hours. Rinse the aerogel microspheres with deionized water 2-3 times and dry them at 60-70℃ until the moisture content is 15-18% to obtain microbially modified aerogel microspheres. S3. Add cellulose nanofibers to deionized water and disperse them by ultrasonication for 15-30 min to prepare a nanofiber dispersion with a mass concentration of 0.5%-1.5%; S4. After separating the egg whites, refrigerate them to 4~6℃, add the nanofiber dispersion, stir and beat until neutral foaming to obtain nanofiber-reinforced egg white foam; S5. Add the microbially modified aerogel microspheres and black fungus polysaccharide to the rice slurry, stir and mix evenly to obtain a mixed rice paste; S6. Gently mix the nanofiber-reinforced egg white foam with the mixed rice paste, extrude it to obtain rice cake blanks, bake the rice cake blanks, and cool them to obtain rice cakes rich in black fungus polysaccharides.

[0008] Furthermore, in S1, the mass ratio of broken rice, natural polysaccharide excipient, and deionized water is (8-10):1:(30-50); the natural polysaccharide excipient is a mixture of chitosan and sodium alginate, and the mass ratio of chitosan to sodium alginate is (1~3):1.

[0009] Furthermore, the freeze-drying conditions described in S1 are -40~-60℃, vacuum degree -0.08~-0.1MPa, and drying time 12~24h; the supercritical drying uses CO2 as the drying medium, with a drying temperature of 35~45℃, a pressure of 8~12MPa, and a drying time of 2~4h.

[0010] Furthermore, in the fermentation system described in S2, the inoculum amount of Bacillus subtilis is 5-10%, and the fermentation substrate is glucose-peptone medium; during the fermentation process, the mixture is stirred once every 12 hours at a stirring speed of 100-150 r / min.

[0011] Furthermore, the ultrasonic dispersion described in S3 has a power of 200~300W and a frequency of 40kHz.

[0012] Furthermore, in S4, the mass ratio of the nanofiber dispersion to egg white is 1:(10~20); the stirring and whipping speed is 1500~2000 r / min, and the whipping time is 3~5 min.

[0013] Furthermore, in S5, the mass ratio of the microbially modified aerogel microspheres, black fungus polysaccharide, and rice slurry is (10~20):(1~2):100; the stirring speed is 50~80 r / min, the stirring time is 5~10 min, and the mixing temperature is controlled at 25~35℃.

[0014] Furthermore, the rice paste described in S5 is prepared by mixing broken rice and whole rice at a mass ratio of 3:7, adding 3 times the mass of deionized water, gelatinizing at 80°C for 30 minutes, and homogenizing with a colloid mill.

[0015] Furthermore, the mass ratio of the nanofiber-reinforced egg white foam and the mixed rice paste described in S6 is 1:(3~5).

[0016] Furthermore, the extrusion molding pressure described in S6 is 0.3~0.5MPa, the thickness of the rice cake blank is 0.8~1.2cm, and the baking adopts segmented baking, first baking at 80℃ for 30min, and then baking at 110℃ for 60~80min.

[0017] The present invention also provides rice cakes rich in black fungus polysaccharides prepared by the above method. Beneficial effects

[0018] 1. This invention forms a closed loop through the physical anti-adhesion of aerogel microcarriers and the bio-toughening of a dual microbial network, ensuring molding and structural stability. The nanofiber-reinforced foam structure and the porous structure of aerogel work together to promote rapid moisture evaporation and improve crispness. At the same time, it encapsulates black fungus polysaccharides to prevent high-temperature denaturation, ultimately achieving comprehensive optimization of product performance. 2. This invention prepares aerogel microspheres by synergistically combining broken rice starch with natural polysaccharides such as chitosan / sodium alginate. Utilizing their ultra-high specific surface area, they form a "dry sponge" structure, achieving the effect of physically locking free starch and preventing broken rice from sticking to the wall. The main reason is that the porous structure of the aerogel microspheres can adsorb free starch molecules in the rice slurry that easily cause adhesion, reducing the adhesive forces between starch molecules. Simultaneously, it reduces the adsorption tendency of raw materials and processing equipment surfaces, fundamentally blocking the path of wall adhesion and solving problems such as molding difficulties and raw material loss caused by broken rice adhesion in traditional processes. 3. This invention utilizes a dual-network microbial technology (Bacillus subtilis fermentation modification) to form an "extracellular polysaccharide-starch" dual-network structure on the surface of aerogel microspheres. This achieves the effect of strengthening the structural toughness of rice cakes and further reducing the tendency to stick together at the biochemical level. The metabolites of Bacillus subtilis (extracellular polysaccharides) can cross-link with starch molecules to form a stable network, which not only enhances the structural stability of aerogel microspheres and repairs microscopic cracks that may occur during processing, but also degrades some free starch into oligosaccharides, reducing the binding sites at the molecular level. At the same time, it improves the flavor and nutritional value of the product, achieving a triple benefit of anti-sticking, toughening, and flavor enhancement. 4. This invention strengthens the foam wall with nanofibers by interlacing cellulose nanofibers into the egg white foam wall to construct a "reinforced concrete" structure, thereby improving the foam's toughness, compressive strength, and high-temperature stability, and preventing defoaming and collapse during rice cake baking. Cellulose nanofibers have excellent mechanical strength and dispersibility, which can effectively resist the shear force and temperature change impact during mixing and baking, prevent the foam wall from breaking, and provide a stable porous structure foundation for rice cakes, solving the technical problem that traditional egg white foam is prone to defoaming and difficult to maintain structural stability in food processing. 5. This invention is based on the modification and synergistic effect of natural raw materials (broken rice, natural polysaccharides, microorganisms, and cellulose nanofibers). By optimizing the process to replace the function of chemical additives, it reduces raw material waste and equipment cleaning costs during processing. Furthermore, through the oligosaccharides produced by microbial metabolism and the black fungus polysaccharides that retain complete activity, it achieves nutritional upgrades for the product, meeting the needs of healthy food consumers. Attached Figure Description

[0019] Figure 1 Photographs showing the appearance of the rice cakes prepared in Example 4 and Comparative Example 3; Figure 2 The images show scanning electron microscope (SEM) images of the rice cakes prepared in Example 4 and Comparative Example 3. Detailed Implementation

[0020] This invention proposes a rice cake rich in black fungus polysaccharides and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following will provide a more detailed description of the invention with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0021] The broken rice used below is from broken rice of low-cadmium-accumulating rice varieties; The following rice paste is prepared by mixing broken rice and whole rice in a mass ratio of 3:7, adding 3 times the mass of deionized water, gelatinizing at 80°C for 30 minutes, and homogenizing with a colloid mill.

[0022] Example 1 A method for preparing rice cakes rich in black fungus polysaccharides includes the following steps: S1. 8g of broken rice was crushed, passed through an 80-mesh sieve, mixed with 0.5g of chitosan and 0.5g of sodium alginate, and 30g of deionized water was added to prepare a homogeneous slurry. The slurry was then freeze-dried at -40℃ and -0.08MPa for 12h and then dried with supercritical CO2 at 35℃ and 8MPa for 2h to prepare broken rice starch aerogel microspheres. S2. Place 1g of broken rice starch aerogel microspheres into 10mL of Bacillus subtilis fermentation system (Bacillus subtilis inoculum amount is 5%, fermentation substrate is glucose-peptone medium), ferment at 30℃ and pH 6.5 for 48h. Stir once every 12h during fermentation at a stirring speed of 100r / min. Rinse the aerogel microspheres twice with deionized water and dry at 60℃ to a moisture content of 15% to obtain microbially modified aerogel microspheres. S3. Add cellulose nanofibers to deionized water and disperse them by ultrasonication at 200W and 40kHz for 15min to prepare a nanofiber dispersion with a mass concentration of 0.5%. S4. After separating 10g of egg white, refrigerate it to 4℃, add 1g of nanofiber dispersion, and stir and beat at 1500r / min for 3min to obtain nanofiber-reinforced egg white foam; S5. Add 10g of microbially modified aerogel microspheres and 1g of black fungus polysaccharide to 100g of rice paste, stir and mix at 50r / min and 25℃ for 5min to obtain mixed rice paste; S6. Gently mix 1g of nanofiber-reinforced egg white foam with 3g of mixed rice paste, and extrude it at 0.3MPa to obtain a rice cake blank with a thickness of 0.8cm. Bake the rice cake blank at 80℃ for 30min, then at 110℃ for 60min. After cooling, obtain a rice cake rich in black fungus polysaccharides.

[0023] Example 2 A method for preparing rice cakes rich in black fungus polysaccharides includes the following steps: S1. 9g of broken rice was crushed, passed through an 80-mesh sieve, mixed with 0.6g of chitosan and 0.4g of sodium alginate, and 35g of deionized water was added to prepare a homogeneous slurry. The slurry was then freeze-dried at -45℃ and -0.085MPa for 16h and then dried with supercritical CO2 at 38℃ and 9MPa for 2.5h to prepare broken rice starch aerogel microspheres. S2. Place 1g of broken rice starch aerogel microspheres into 12mL of Bacillus subtilis fermentation system (the inoculum amount of Bacillus subtilis is 6%, and the fermentation substrate is glucose-peptone medium), and ferment at 32℃ and pH 6.8 for 54h. Stir once every 12h during the fermentation process at a stirring speed of 120r / min. Rinse the aerogel microspheres twice with deionized water and dry them at 62℃ until the moisture content is 16% to obtain microbially modified aerogel microspheres. S3. Cellulose nanofibers were added to deionized water and ultrasonically dispersed at 220W and 40kHz for 18 minutes to prepare a nanofiber dispersion with a mass concentration of 0.8%. S4. After separating 12g of egg white, refrigerate it to 4℃, add 1g of nanofiber dispersion, and stir and beat at 1600r / min for 3.5min to obtain nanofiber-reinforced egg white foam; S5. Add 12g of microbially modified aerogel microspheres and 1.2g of black fungus polysaccharide to 100g of rice paste, stir and mix at 60r / min and 28℃ for 6min to obtain mixed rice paste; S6. Gently mix 1g of nanofiber-reinforced egg white foam with 3.5g of mixed rice paste, and extrude it at 0.35MPa to obtain a rice cake blank with a thickness of 0.9cm. Bake the rice cake blank at 80℃ for 30min, then at 110℃ for 65min. After cooling, obtain a rice cake rich in black fungus polysaccharides.

[0024] Example 3 A method for preparing rice cakes rich in black fungus polysaccharides includes the following steps: S1. 9g of broken rice was crushed, passed through a 90-mesh sieve, mixed with 0.67g of chitosan and 0.33g of sodium alginate, and 40g of deionized water was added to make a homogeneous slurry. The slurry was then freeze-dried at -50℃ and vacuum degree -0.09MPa for 20h and then dried with supercritical CO2 at 40℃ and 10MPa for 3h to prepare broken rice starch aerogel microspheres. S2. Place 1g of broken rice starch aerogel microspheres into 15mL of Bacillus subtilis fermentation system (Bacillus subtilis inoculum amount of 7%, fermentation substrate is glucose-peptone medium), ferment at 34℃ and pH 7.0 for 60h. Stir once every 12h during fermentation, stirring speed is 130r / min. Rinse the aerogel microspheres with deionized water 3 times, and dry at 65℃ to a moisture content of 17% to obtain microbially modified aerogel microspheres. S3. Add cellulose nanofibers to deionized water and disperse them by ultrasonication at 250W and 40kHz for 22min to prepare a nanofiber dispersion with a mass concentration of 1.0%. S4. After separating 15g of egg white, refrigerate it to 5℃, add 1g of nanofiber dispersion, and stir and beat at 1800r / min for 4min to obtain nanofiber-reinforced egg white foam; S5. Add 15g of microbially modified aerogel microspheres and 1.5g of black fungus polysaccharide to 100g of rice paste, stir and mix at 70r / min and 30℃ for 8min to obtain mixed rice paste; S6. Gently mix 1g of nanofiber-reinforced egg white foam with 4g of mixed rice paste, and extrude it at 0.4MPa to obtain a rice cake blank with a thickness of 1.0cm. Bake the rice cake blank at 80℃ for 30min, then at 110℃ for 70min. After cooling, obtain a rice cake rich in black fungus polysaccharides.

[0025] Example 4 A method for preparing rice cakes rich in black fungus polysaccharides includes the following steps: S1. 9g of broken rice was crushed, passed through a 100-mesh sieve, mixed with 0.67g of chitosan and 0.33g of sodium alginate, and 40g of deionized water was added to make a homogeneous slurry. The slurry was then freeze-dried at -50℃ and vacuum degree -0.09MPa for 20h and then dried with supercritical CO2 at 40℃ and 10MPa for 3h to prepare broken rice starch aerogel microspheres. S2. Place 1g of broken rice starch aerogel microspheres into 15mL of Bacillus subtilis fermentation system (Bacillus subtilis inoculum amount is 8%, fermentation substrate is glucose-peptone medium), ferment at 35℃ and pH 7.0 for 60h. Stir once every 12h during fermentation, stirring speed is 130r / min. Rinse the aerogel microspheres with deionized water 3 times, and dry at 65℃ to a moisture content of 17% to obtain microbially modified aerogel microspheres. S3. Add cellulose nanofibers to deionized water and disperse them by ultrasonication at 250W and 40kHz for 25min to prepare a nanofiber dispersion with a mass concentration of 1.0%. S4. After separating 15g of egg white, refrigerate it to 5℃, add 1g of nanofiber dispersion, and stir and beat at 1800r / min for 4min to obtain nanofiber-reinforced egg white foam; S5. Add 15g of microbially modified aerogel microspheres and 1.5g of black fungus polysaccharide to 100g of rice paste, stir and mix at 70r / min and 30℃ for 8min to obtain mixed rice paste; S6. Gently mix 1g of nanofiber-reinforced egg white foam with 4g of mixed rice paste, and extrude it at 0.4MPa to obtain a rice cake blank with a thickness of 1.0cm. Bake the rice cake blank at 80℃ for 30min, then at 110℃ for 70min. After cooling, obtain a rice cake rich in black fungus polysaccharides.

[0026] Example 5 A method for preparing rice cakes rich in black fungus polysaccharides includes the following steps: S1. 10g of broken rice was crushed, passed through a 100-mesh sieve, mixed with 0.71g of chitosan and 0.29g of sodium alginate, and 45g of deionized water was added to make a homogeneous slurry. The slurry was then freeze-dried at -55℃ and vacuum degree -0.095MPa for 22h and supercritical CO2 drying at 42℃ and pressure 11MPa for 3.5h to prepare broken rice starch aerogel microspheres. S2. Place 1g of broken rice starch aerogel microspheres into 18mL of Bacillus subtilis fermentation system (Bacillus subtilis inoculum amount of 9%, fermentation substrate is glucose-peptone medium), ferment at 36℃ and pH 7.2 for 66h, stirring once every 12h during fermentation at a stirring speed of 140r / min, rinse the aerogel microspheres with deionized water 3 times, and dry at 68℃ to a moisture content of 17% to obtain microbially modified aerogel microspheres; S3. Cellulose nanofibers were added to deionized water and ultrasonically dispersed at 280W and 40kHz for 28 minutes to prepare a nanofiber dispersion with a mass concentration of 1.2%. S4. After separating 18g of egg white, refrigerate it to 6℃, add 1g of nanofiber dispersion, and stir and beat at 1900r / min for 4.5min to obtain nanofiber-reinforced egg white foam; S5. Add 18g of microbially modified aerogel microspheres and 1.8g of black fungus polysaccharide to 100g of rice paste, stir and mix at 75r / min and 32℃ for 9min to obtain mixed rice paste; S6. Gently mix 1g of nanofiber-reinforced egg white foam with 4.5g of mixed rice paste, and extrude it at 0.45MPa to obtain a rice cake blank with a thickness of 1.1cm. Bake the rice cake blank at 80℃ for 30min, then at 110℃ for 75min. After cooling, obtain a rice cake rich in black fungus polysaccharides.

[0027] Example 6 A method for preparing rice cakes rich in black fungus polysaccharides includes the following steps: S1. 10g of broken rice was crushed, passed through a 100-mesh sieve, mixed with 0.75g of chitosan and 0.25g of sodium alginate, and 50g of deionized water was added to make a homogeneous slurry. The slurry was then freeze-dried at -60℃ and vacuum degree -0.1MPa for 24h and then dried with supercritical CO2 at 45℃ and 12MPa for 4h to prepare broken rice starch aerogel microspheres. S2. Place 1g of broken rice starch aerogel microspheres in 20mL of Bacillus subtilis fermentation system (Bacillus subtilis inoculum amount is 10%, fermentation substrate is glucose-peptone medium), ferment at 37℃ and pH 7.5 for 72h. Stir once every 12h during fermentation, stirring speed is 150r / min. Rinse the aerogel microspheres with deionized water 3 times, and dry at 70℃ to a moisture content of 18% to obtain microbially modified aerogel microspheres. S3. Add cellulose nanofibers to deionized water and disperse them by ultrasonication at 300W and 40kHz for 30min to prepare a nanofiber dispersion with a mass concentration of 1.5%. S4. After separating 20g of egg white, refrigerate it to 6℃, add 1g of nanofiber dispersion, stir and beat at 2000r / min for 5min to obtain nanofiber-reinforced egg white foam; S5. Add 20g of microbially modified aerogel microspheres and 2g of black fungus polysaccharide to 100g of rice paste, stir and mix at 80r / min and 35℃ for 10min to obtain mixed rice paste; S6. Gently mix 1g of nanofiber-reinforced egg white foam with 5g of mixed rice paste, and extrude it at 0.5MPa to obtain a rice cake blank with a thickness of 1.2cm. Bake the rice cake blank at 80℃ for 30min, then at 110℃ for 80min. After cooling, obtain a rice cake rich in black fungus polysaccharides.

[0028] Example 7 A method for preparing rice cakes rich in black fungus polysaccharides includes the following steps: S1. 8g of broken rice was crushed, passed through a 90-mesh sieve, mixed with 0.67g of chitosan and 0.33g of sodium alginate, and 38g of deionized water was added to prepare a homogeneous slurry. The slurry was then freeze-dried at -48℃ and -0.088MPa for 18h and then dried with supercritical CO2 at 39℃ and 9.5MPa for 2.8h to prepare broken rice starch aerogel microspheres. S2. Place 1g of broken rice starch aerogel microspheres in 14mL of Bacillus subtilis fermentation system (the inoculum amount of Bacillus subtilis is 7.5%, and the fermentation substrate is glucose-peptone medium), and ferment at 33℃ and pH 6.9 for 57h. Stir once every 12h during the fermentation process at a stirring speed of 125r / min. Rinse the aerogel microspheres twice with deionized water and dry them at 63℃ until the moisture content is 16.5% to obtain microbially modified aerogel microspheres. S3. Add cellulose nanofibers to deionized water and disperse them by ultrasonication at 240W and 40kHz for 20min to prepare a nanofiber dispersion with a mass concentration of 0.9%. S4. After separating 14g of egg white, refrigerate it to 5℃, add 1g of nanofiber dispersion, and stir and beat at 1700r / min for 3.8min to obtain nanofiber-reinforced egg white foam; S5. Add 14g of microbially modified aerogel microspheres and 1.4g of black fungus polysaccharide to 100g of rice paste, stir and mix at 65r / min and 29℃ for 7min to obtain mixed rice paste; S6. Gently mix 1g of nanofiber-reinforced egg white foam with 3.8g of mixed rice paste, and extrude it at 0.38MPa to obtain a rice cake blank with a thickness of 0.95cm. Bake the rice cake blank at 80℃ for 30min, then at 110℃ for 68min. After cooling, obtain a rice cake rich in black fungus polysaccharides.

[0029] Example 8 A method for preparing rice cakes rich in black fungus polysaccharides includes the following steps: S1. 9.5g of broken rice was pulverized, passed through a 95-mesh sieve, mixed with 0.69g of chitosan and 0.31g of sodium alginate, and 42g of deionized water was added to prepare a homogeneous slurry. The slurry was then freeze-dried at -52℃ and -0.092MPa for 21h and then dried with supercritical CO2 at 41℃ and 10.5MPa for 3.2h to prepare broken rice starch aerogel microspheres. S2. Place 1g of broken rice starch aerogel microspheres in 16mL of Bacillus subtilis fermentation system (Bacillus subtilis inoculum amount is 8.5%, fermentation substrate is glucose-peptone medium), ferment at 35℃ and pH 7.1 for 63h. Stir once every 12h during fermentation, stirring speed is 135r / min. Rinse the aerogel microspheres with deionized water 3 times, and dry at 66℃ to a moisture content of 17.2% to obtain microbially modified aerogel microspheres. S3. Cellulose nanofibers were added to deionized water and ultrasonically dispersed at 260W and 40kHz for 26 minutes to prepare a nanofiber dispersion with a mass concentration of 1.1%. S4. After separating 16g of egg white, refrigerate it to 5℃, add 1g of nanofiber dispersion, and stir and beat at 1850r / min for 4.2min to obtain nanofiber-reinforced egg white foam; S5. Add 16g of microbially modified aerogel microspheres and 1.6g of black fungus polysaccharide to 100g of rice paste, and stir at 72r / min and 31℃ for 8.5min to obtain mixed rice paste; S6. Gently mix 1g of nanofiber-reinforced egg white foam with 4.2g of mixed rice paste, and extrude it at 0.42MPa to obtain a rice cake blank with a thickness of 1.05cm. Bake the rice cake blank at 80℃ for 30min, then at 110℃ for 72min. After cooling, obtain a rice cake rich in black fungus polysaccharides.

[0030] Comparative Example 1 The difference between this comparative example and Example 4 is that only freeze-drying was performed in S1, without supercritical CO2 drying. The remaining steps and parameters are completely consistent with those of Example 4.

[0031] Comparative Example 2 The difference between this comparative example and Example 4 is that the inoculum amount of Bacillus subtilis in S2 is 4%, while the remaining steps and parameters are completely consistent with Example 4.

[0032] Comparative Example 3 The difference between this comparative example and Example 4 is that Bacillus subtilis fermentation was not performed in S2. Instead, the broken rice starch aerogel microspheres were directly washed, dried, and used in subsequent steps. The remaining steps and parameters were completely consistent with those of Example 4.

[0033] Comparative Example 4 The difference between this comparative example and Example 4 is that the mass concentration of the nanofiber dispersion in S3 is 0.3%, while the remaining steps and parameters are completely consistent with those in Example 4.

[0034] Comparative Example 5 The difference between this comparative example and Example 4 is that no nanofiber dispersion was added in S4, and egg white was directly whipped to prepare egg white foam. The remaining steps and parameters are completely consistent with those in Example 4.

[0035] Comparative Example 6 The difference between this comparative example and Example 4 is that the amount of microbially modified aerogel microspheres used in S5 is 8g, while the remaining steps and parameters are completely consistent with Example 4.

[0036] Comparative Example 7 The difference between this comparative example and Example 4 is that the mass ratio of nanofiber-reinforced egg white foam to mixed rice paste in S6 is 1:2, while the remaining steps and parameters are completely consistent with Example 4.

[0037] Comparative Example 8 The difference between this comparative example and Example 4 is that no black fungus polysaccharide is added in S5, while the remaining steps and parameters are completely consistent with Example 4. Performance testing:

[0038] Moisture content determination: Refer to GB 5009.3-2016 "National Food Safety Standard - Determination of Moisture in Food" and use the direct drying method. Take about 2g of sample, place it in a pre-weighed weighing bottle, weigh accurately, and then dry it in a 105℃ constant temperature drying oven until constant weight. Calculate the moisture content of the sample. Each sample is measured in triplicate, and the average value is taken. Product hardness was determined using a Brookfield CT3 physical property tester. A puncture test was performed using a TA7 probe. Test conditions were: pre-test speed 2 mm / s, test speed 1 mm / s, post-test speed 10 mm / s, trigger force 2.04 g. Three different sites were selected for each sample, and the average value was taken as the final hardness value. Chewing property determination: A Brookfield CT3 physical property analyzer was used in texture profile analysis (TPA) mode with a TA36R probe. Test conditions: pre-test speed 1 mm / s, test speed 1 mm / s, post-test speed 1 mm / s, compression ratio 50%, trigger force 2.04 g. Each sample was measured in triplicate. Chewing property values ​​were automatically calculated by the instrument's software, and the average value was taken. Brittleness determination: A Brookfield CT3 physical property analyzer was used in the three-point bending test method with a TA4 probe. Test conditions: pre-test speed 2 mm / s, test speed 1 mm / s, post-test speed 5 mm / s, span 30 mm, trigger force 2.04 g. Brittleness was expressed as the maximum force at which the sample broke. Each sample was measured in triplicate, and the average value was taken. Determination of the retention rate of polysaccharides in black fungus: The phenol-sulfuric acid colorimetric method was used. First, polysaccharides were extracted from the sample. 1 mL of the polysaccharide extract was accurately pipetted, 1 mL of phenol reagent was added, and the mixture was shaken well. Then, 5 mL of concentrated sulfuric acid was slowly added. The mixture was heated in a boiling water bath for 15 min, cooled to room temperature, and the absorbance was measured at 490 nm. Simultaneously, a standard curve was plotted using a standard glucose solution, and the polysaccharide content in the sample was calculated. Combined with the initial polysaccharide content in the raw material (pre-determined using the phenol-sulfuric acid colorimetric method: 1 g of unprocessed black fungus polysaccharide raw material was processed according to the above extraction method, and the initial polysaccharide content was measured to be 85.6%), the polysaccharide activity retention rate was calculated. Each sample was measured in triplicate, and the average value was taken. Determination of DPPH free radical scavenging rate: The DPPH method was used. A precise 0.1 mmol / L DPPH ethanol solution was prepared. 2 mL of the DPPH solution was mixed with 1 mL of the sample extract, and the mixture was reacted in the dark for 30 min. The absorbance was then measured at 517 nm. Anhydrous ethanol was used as a blank control, and vitamin C as a positive control. The DPPH free radical scavenging rate of the samples was calculated. Each sample was measured in triplicate, and the average value was taken. Determination of reducing power (absorbance): The potassium ferricyanide reduction method was used. Take 1 mL of sample extract, add 2.5 mL of 0.2 mol / L phosphate buffer (pH 6.6) and 2.5 mL of 1% potassium ferricyanide solution, heat in a 50℃ water bath for 20 min, cool, add 2.5 mL of 10% trichloroacetic acid solution, centrifuge for 10 min (3000 r / min); take 2.5 mL of the supernatant, add 2.5 mL of distilled water and 0.5 mL of 0.1% ferric chloride solution, shake well, and measure the absorbance at 700 nm. The higher the absorbance value, the stronger the reducing power of the sample. Each sample was measured in triplicate, and the average value was taken. Sticking to the mold wall: Sensory evaluation combined with actual processing observation was used. During the rice cake processing and shaping process, the degree of sticking to the inner wall of the mold was observed and divided into 3 levels based on the sensory evaluation criteria: no sticking (no sample residue on the inner wall of the mold, and the rice cake can be easily removed after shaping), no obvious sticking (a small amount of sample residue on the inner wall of the mold, which can be easily wiped away, and the rice cake is intact), and obvious sticking (a large amount of sample residue on the inner wall of the mold, which is difficult to wipe away, and the edges of the rice cake are damaged and stick to the mold after shaping). Each sample was processed 3 times, and the sticking situation was recorded. Sensory evaluation: Scores are given according to the quality evaluation criteria table in Table 1 below, with three parallel evaluations and the average value is taken. Table 1 Quality Scoring Criteria

[0039] The results are shown in Tables 2-4 below: Table 2 Physicochemical Properties

[0040] As shown in Table 2 above, the physicochemical properties of the black fungus polysaccharide rice cakes prepared in each embodiment of the present invention are generally superior to those of the comparative examples. Regarding moisture content, the moisture content of the embodiments ranges from 8.6% to 11.8%, with Example 6 having the lowest (8.6%) and Example 1 the highest (11.8%). In contrast, the moisture content of the comparative examples ranges from 9.4% to 12.5%, with Comparative Example 1 having the highest (12.5%), both higher than the corresponding embodiments. This demonstrates that the process of the present invention can effectively control the moisture content of the rice cakes, avoiding the deterioration of texture caused by excessive moisture. Regarding hardness, the hardness of the embodiments ranges from 17.8N to 23.5N, with Example 4 having the lowest hardness (17.8N) and the softest texture. The hardness of the comparative examples ranges from 20.1N to 28.6N, with Comparative Example 1 having the highest hardness (28.6N), significantly higher than all embodiments. Regarding chewiness, the chewiness range of the examples was 21.5 N·mm to 28.6 N·mm, with Example 4 having the lowest (21.5 N·mm), indicating the least chewing burden. The chewiness range of the comparative examples was 25.3 N·mm to 33.2 N·mm, with Comparative Example 1 having the highest (33.2 N·mm), indicating greater chewing difficulty. Regarding crispness, the crispness range of the examples was 16.2 N to 18.2 N, a moderate value, resulting in a crisp but not hard texture. The crispness range of the comparative examples was 17.1 N to 20.1 N, with Comparative Example 1 having the highest crispness (20.1 N), indicating a hard and crisp texture with poor palatability. Overall, Example 4 had the best physicochemical indicators. The comparative examples generally had problems with high moisture content, excessive hardness and chewiness, and unsuitable crispness, fully demonstrating that the process of this invention can precisely optimize the physicochemical properties of rice cakes and improve the texture and taste of the product.

[0041] Depend on Figure 1 and Figure 2 It can be seen that the rice cakes prepared in Example 4 exhibit significant advantages in both macroscopic appearance and microstructure. Figure 1 As can be seen from the appearance photos, the rice cake in Example 4 has a smooth and even surface, smooth edges without any damage, no residue stuck to the mold, and a uniform color; while the rice cake in Comparative Example 3 has a rough surface, wrinkled and damaged edges, and obvious residue stuck to the mold. Figure 2 The scanning electron microscope (SEM) images show that in the cross-sectional microstructure of the rice cake in Example 4, the pores are densely distributed, uniform in size, and the nanofibers are evenly interspersed between the pore walls, forming a stable support network. In contrast, in the microstructure of Comparative Example 3, the pores are large and uneven, some pores are merged and connected, and there is no obvious stable network structure, which leads to its higher hardness and poorer chewability.

[0042] Table 3 Functional Characteristics

[0043] As shown in Table 3 above, the black fungus polysaccharide rice cakes of each embodiment exhibit significantly better functional characteristics than the comparative examples. Regarding the retention rate of black fungus polysaccharide activity, the retention rates of the embodiments ranged from 85.2% to 91.7%, which was generally high. Example 4 had the highest retention rate (91.7%), while Example 1 had the lowest (85.2%). The retention rates of the comparative examples ranged from 78.3% to 87.1%. Comparative example 8, which did not contain black fungus polysaccharide, had no detection results for polysaccharide activity retention, thus providing a blank baseline for the functional characteristics of the rice cakes. Comparative example 3 had the lowest retention rate (78.3%), while comparative example 7 had the highest (87.1%), but both were still lower than Example 1, which had the lowest retention rate among the embodiments. This indicates that the process of the present invention can effectively reduce the loss of black fungus polysaccharide activity during processing and maximize the preservation of its nutritional functions. Regarding DPPH free radical scavenging rate (reflecting antioxidant capacity), the scavenging rate of the examples ranged from 72.3% to 83.2%, with Example 4 having the highest rate (83.2%) and Example 1 having the lowest (72.3%). The scavenging rate of the comparative examples ranged from 45.6% to 76.3%, with Comparative Example 8 having the lowest rate (45.6%) and Comparative Example 7 having the highest rate (76.3%), all lower than the corresponding indicators of the examples. Regarding reducing power (the higher the absorbance value, the stronger the reducing power), the absorbance of the examples ranged from 0.82 to 0.96, with Example 4 having the highest rate (0.96) and Example 1 having the lowest rate (0.82). The absorbance of the comparative examples ranged from 0.52 to 0.88, with Comparative Example 8 having the lowest rate (0.52) and Comparative Example 7 having the highest rate (0.88). It can be seen that the antioxidant capacity of the rice cake in this example is mainly contributed by black fungus polysaccharide, and the antioxidant properties of the basic raw materials of the rice cake (broken rice, egg white, cellulose nanofibers, etc.) are relatively weak. Regarding the wall adhesion issue, only Example 1 showed slight wall adhesion, Examples 2 and 7 showed no obvious wall adhesion, and the remaining examples showed no wall adhesion. In contrast, Comparative Example 3 showed obvious wall adhesion, Comparative Examples 1 and 5 showed slight wall adhesion, and the remaining comparative examples showed no obvious wall adhesion. This demonstrates that the process of the present invention can effectively improve the wall adhesion problem during processing and reduce raw material loss.

[0044] Table 4 Sensory Evaluation

[0045] As shown in Table 4, the black fungus polysaccharide rice cakes of each embodiment significantly outperformed the comparative examples in all dimensions and total score of sensory evaluation, indicating superior sensory quality. Overall, Example 4 exhibited the best sensory quality, achieving the highest scores across all dimensions and a total score of 95.9. The comparative examples generally suffered from poor color, bland flavor, hard texture, damaged appearance, and uneven texture. This demonstrates that the process of this invention can effectively improve the sensory quality of the rice cakes and enhance the product's market competitiveness.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the technical solutions of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A method for preparing rice cakes rich in black fungus polysaccharides, characterized in that, Includes the following steps: S1. After crushing broken rice and passing it through an 80-100 mesh sieve, mix it with natural polysaccharide excipients, add deionized water to make a homogeneous slurry, and then freeze-dry and supercritical drying to prepare broken rice starch aerogel microspheres. S2. Place broken rice starch aerogel microspheres in a Bacillus subtilis fermentation system and ferment at 30-37℃ and pH 6.5-7.5 for 48-72 hours. Rinse the aerogel microspheres with deionized water 2-3 times and dry them at 60-70℃ until the moisture content is 15-18% to obtain microbially modified aerogel microspheres. S3. Add cellulose nanofibers to deionized water and disperse them by ultrasonication for 15-30 min to prepare a nanofiber dispersion with a mass concentration of 0.5%-1.5%; S4. After separating the egg whites, refrigerate them to 4~6℃, add the nanofiber dispersion, stir and beat until neutral foaming to obtain nanofiber-reinforced egg white foam; S5. Add the microbially modified aerogel microspheres and black fungus polysaccharide to the rice slurry, stir and mix evenly to obtain a mixed rice paste; S6. Gently mix the nanofiber-reinforced egg white foam with the mixed rice paste, extrude it to obtain rice cake blanks, bake the rice cake blanks, and cool them to obtain rice cakes rich in black fungus polysaccharides.

2. The method for preparing rice cakes rich in black fungus polysaccharides according to claim 1, characterized in that, The mass ratio of broken rice, natural polysaccharide excipient and deionized water in S1 is (8-10):1:(30-50); the natural polysaccharide excipient is a mixture of chitosan and sodium alginate, and the mass ratio of chitosan to sodium alginate is (1~3):

1.

3. The method for preparing rice cakes rich in black fungus polysaccharides according to claim 1, characterized in that, The freeze-drying conditions described in S1 are -40~-60℃, vacuum degree -0.08~-0.1MPa, and drying time 12~24h; the supercritical drying uses CO2 as the drying medium, with a drying temperature of 35~45℃, a pressure of 8~12MPa, and a drying time of 2~4h.

4. The method for preparing rice cakes rich in black fungus polysaccharides according to claim 1, characterized in that, In the fermentation system described in S2, the inoculum amount of Bacillus subtilis is 5-10%, and the fermentation substrate is glucose-peptone medium. During the fermentation process, the mixture is stirred once every 12 hours at a stirring speed of 100-150 r / min.

5. The method for preparing rice cakes rich in black fungus polysaccharides according to claim 1, characterized in that, The ultrasonic dispersion described in S3 has a power of 200~300W and a frequency of 40kHz.

6. The method for preparing rice cakes rich in black fungus polysaccharides according to claim 1, characterized in that, The mass ratio of the nanofiber dispersion to egg white in S4 is 1:(10~20); the stirring and whipping speed is 1500~2000r / min, and the whipping time is 3~5min.

7. The method for preparing rice cakes rich in black fungus polysaccharides according to claim 1, characterized in that, The mass ratio of the microbially modified aerogel microspheres, black fungus polysaccharide and rice slurry in S5 is (10~20):(1~2):100; the stirring speed is 50~80r / min, the stirring time is 5~10min, and the mixing temperature is controlled at 25~35℃.

8. The method for preparing rice cakes rich in black fungus polysaccharides according to claim 1, characterized in that, The mass ratio of the nanofiber-reinforced egg white foam and the mixed rice paste described in S6 is 1:(3~5).

9. The method for preparing rice cakes rich in black fungus polysaccharides according to claim 1, characterized in that, The extrusion molding pressure described in S6 is 0.3~0.5MPa, the thickness of the rice cake blank is 0.8~1.2cm, and the baking adopts segmented baking, first baking at 80℃ for 30min, and then baking at 110℃ for 60~80min.

10. Rice cakes rich in black fungus polysaccharides prepared by the method according to any one of claims 1 to 9.

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