Preparation method and application of fermented quinoa powder with high antioxidant activity of pleurotus citrinopileatus

Abstract

The application discloses a preparation method and application of a fermented quinoa powder of Pleurotus citrinopileatus with high antioxidant activity. The method comprises the following steps: preparing a seed solution of the Pleurotus citrinopileatus; preparing a quinoa culture medium; inoculating the seed solution of the Pleurotus citrinopileatus into the quinoa culture medium, adding sterile water, and carrying out fermentation in the dark to obtain a fermentation product; and carrying out freeze-drying treatment on the fermentation product, crushing and sieving to obtain the fermented quinoa powder of the Pleurotus citrinopileatus. The method can effectively improve the contents of protein, total sugar, lysine and total flavonoids in the quinoa and the antioxidant activity, lays a foundation for the factory production of the quinoa with high contents of protein, total sugar, lysine and total flavonoids, and provides a theoretical basis for the commercial production of the quinoa for antioxidant related products in the future. The method has the advantages of low cost, simple process and easy realization of factory production.

Description

Technical Field

[0001] This invention relates to the field of biotechnology, and in particular to a method for preparing and applying fermented quinoa powder with high antioxidant activity. Background Technology

[0002] Quinoa (Chenopodium quinoa) is a grain native to South America with high nutritional value. It is not only rich in protein, containing all nine essential amino acids required by the human body, but also contains total sugars, flavonoids (total flavonoids), dietary fiber, vitamins (B vitamins and E), and various minerals (such as iron, calcium, magnesium, and zinc), showing broad application prospects in functional foods. Lysine, as one of the essential amino acids, plays an important role in promoting children's intellectual development, enhancing memory, maintaining acid-base balance, and participating in fat metabolism; flavonoids are closely related to antioxidant, anti-inflammatory, and antiviral effects. However, existing research on quinoa mostly focuses on optimizing the extraction process of nutrients (such as total flavonoids), with relatively little research on how to increase its total flavonoid and lysine content.

[0003] Therefore, developing a method to increase the lysine and total flavonoid content in quinoa is an urgent problem to be solved. Summary of the Invention

[0004] This invention provides a method for preparing fermented quinoa powder with high antioxidant activity. This method can effectively increase the content of protein, total sugar, lysine and total flavonoids in quinoa and improve its antioxidant activity, resulting in fermented quinoa powder with high protein, total sugar, total flavonoid and lysine content, high antioxidant activity, low water holding capacity, low oil holding capacity, high emulsification and high in vitro digestibility.

[0005] The present invention also provides a fermented quinoa powder with Pleurotus ostreatus, which is prepared by the above-mentioned method for preparing fermented quinoa powder with high antioxidant activity. Therefore, the fermented quinoa powder with Pleurotus ostreatus has the advantages of high protein, total sugar, total flavonoid and lysine content, high antioxidant activity, low water holding capacity, low oil holding capacity, high emulsification and high in vitro digestibility.

[0006] This invention also provides a method for preparing fermented quinoa powder with high antioxidant activity, specifically the fermented quinoa powder obtained from the above-mentioned method, or the application of the above-mentioned fermented quinoa powder in improving the hardness and / or elasticity of protein foods. The inventors' research indicates that the fermented quinoa powder prepared by this method can be used to prepare protein bars.

[0007] This invention also provides a method for preparing fermented quinoa powder with high antioxidant activity, which is then applied to quinoa cultivation. Quinoa is cultivated using the above method. Research by the inventors shows that the fermented quinoa powder prepared by this method has higher protein, total sugar, lysine, and total flavonoid content, as well as higher antioxidant activity than the quinoa powder in Comparative Example 1. Therefore, this method can be used to cultivate quinoa.

[0008] The first aspect of the present invention provides a method for preparing fermented quinoa powder with high antioxidant activity, comprising:

[0009] The *Pleurotus ostreatus* strain was inoculated into a solid culture medium at a volume ratio of 8%–10% (V / W) and cultured in the dark to obtain a solid strain.

[0010] The solid strain was inoculated into liquid culture medium at an inoculation rate of 8% to 10% (V / W) and then stirred to obtain Pleurotus ostreatus seed liquid.

[0011] The soaked quinoa was sterilized to obtain quinoa culture medium;

[0012] The seed liquid of Pleurotus ostreatus was inoculated into the quinoa culture medium, and sterile water was added at the same time. After fermentation in the dark, the fermentation product was obtained.

[0013] The fermentation product was freeze-dried, pulverized, and sieved to obtain Golden Top Pleurotus ostreatus fermented quinoa powder.

[0014] The method for preparing fermented quinoa powder with high antioxidant activity as described above, wherein the freeze-drying process sequentially includes a pre-freeze-drying process and a main freeze-drying process;

[0015] In the pre-freeze-drying process, the temperature is -45 to -30°C, and the time is 1 to 3 hours.

[0016] The main freeze-drying process is carried out according to a freeze-drying program, which includes the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth segments executed sequentially. From the first segment to the ninth segment, the temperature is controlled and gradually increased.

[0017] The preparation method of fermented quinoa powder with high antioxidant activity as described above, specifically controls the parameters of the freeze-drying process as follows:

[0018] First section: Temperature -52~-48℃, normal pressure, time 4~6h;

[0019] Second section: Temperature -42~-38℃, vacuum degree 22pa, time 2~4h;

[0020] Third section: Temperature -32~-28℃, vacuum degree 22pa, time 4~6h;

[0021] Fourth section: Temperature -20 to -15℃, vacuum degree 22 Pa, time 2 to 5 hours;

[0022] Fifth section: Temperature -12 to -8℃, vacuum degree 22 Pa, time 1 to 3 hours;

[0023] Section 6: Temperature -6 to -2℃, vacuum degree 22 Pa, time 1 to 3 hours;

[0024] Section 7: Temperature 2–6℃, Vacuum 10 Pa, Time 6–10 h;

[0025] Section 8: Temperature 10–20℃, vacuum 10 Pa, time 3–5 h;

[0026] Section 9: Temperature 25-35℃, vacuum 10pa, time 6-10h.

[0027] The preparation method of fermented quinoa powder with high antioxidant activity as described above, wherein the sterilization treatment of soaked quinoa to obtain quinoa culture medium specifically includes: soaking 50-60g of quinoa in water for 10-14h to obtain soaked quinoa, and then sterilizing the soaked quinoa at 110-130℃ for 20-30min to obtain quinoa culture medium.

[0028] The preparation method of fermented quinoa powder with high antioxidant activity as described above, wherein the volume-to-mass ratio of the Pleurotus ostreatus seed liquid to the quinoa culture medium is (8-10 mL): (50-60 g dry weight);

[0029] And / or, the volume-to-mass ratio of the sterile water to the quinoa culture medium is (8-10 mL): (50-60 g dry weight).

[0030] The preparation method of fermented quinoa powder with high antioxidant activity as described above, wherein the light-protected culture temperature is 25-28°C and the time is 10-12 days;

[0031] And / or, the temperature of the stirring culture is 25-28°C, the rotation speed is 120-150 rpm, and the time is 10-12 days;

[0032] And / or, the light-protected fermentation temperature is 25-28°C, and the time is 20-22 days.

[0033] The preparation method of fermented quinoa powder with high antioxidant activity as described above, wherein the quinoa is any one of black quinoa, white quinoa, and red quinoa;

[0034] And / or, the solid culture medium is potato dextrose agar medium, and the components and contents of the potato dextrose agar medium are as follows: potato extract powder 12g / L, glucose 20g / L, agar 14g / L;

[0035] And / or, the liquid culture medium consists of the following components by weight-volume ratio g / mL: 30% potato juice, 4% glucose, 0.1% KH2PO4, 0.1% MgSO4·7H2O, and the remainder is water.

[0036] A second aspect of the present invention provides a fermented quinoa powder with Pleurotus ostreatus, wherein the fermented quinoa powder with Pleurotus ostreatus is prepared by the method for preparing fermented quinoa powder with Pleurotus ostreatus having high antioxidant activity.

[0037] The third aspect of the present invention provides a method for preparing fermented quinoa powder with high antioxidant activity, the fermented quinoa powder obtained by the method described above, or the application of the fermented quinoa powder described above in the preparation of protein foods.

[0038] The fourth aspect of the present invention provides an application of the method for preparing fermented quinoa powder with high antioxidant activity described above in quinoa cultivation, wherein quinoa is cultivated using the method described above.

[0039] The solution of the present invention has at least the following effects:

[0040] The present invention provides a method for preparing fermented quinoa powder with high antioxidant activity. This method can effectively improve the protein, total sugar, lysine and total flavonoid content and antioxidant activity of quinoa, laying the foundation for the industrial production of quinoa with high protein, total sugar, total flavonoid and lysine content, and providing a theoretical basis for the future commercial production of antioxidant-related products using quinoa. The fermented quinoa powder prepared by this method is characterized by high protein, total sugar, total flavonoids, and lysine content, high antioxidant activity, low water-holding capacity, low oil-holding capacity, high emulsification, and high in vitro digestibility. Its low water-holding capacity makes it easier to form a dry, crisp texture during processing (such as baking, frying, or puffing), making it suitable for developing quinoa chips, cereal bars, biscuits, and other snacks that require a crisp texture. Its low oil-holding capacity reduces oil absorption during frying or pan-frying, making it suitable as a healthy coating (such as for tempura or fried chicken substitutes), reducing the final product's fat content and aligning with low-fat dietary trends. Its high emulsification indicates that the fermented quinoa powder is easier to emulsify, showing potential application value in cosmetics and other fields. Its high in vitro digestibility helps improve the utilization rate of nutrients in quinoa. This method has advantages such as low cost, simple process, and ease of industrial production.

[0041] The fermented quinoa powder with golden top pine mushroom provided by this invention has the advantages of high protein, total sugar, total flavonoid and lysine content, high antioxidant activity, low water holding capacity, low oil holding capacity, high emulsification and high in vitro digestibility, and has broad application prospects in the fields of food and cosmetics. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 The results of water-holding and oil-holding tests are for the fermented quinoa powder from Pleurotus ostreatus in Example 1 and the quinoa powder from Comparative Example 1.

[0044] Figure 2 The results show the emulsification properties of the fermented quinoa powder from Pleurotus ostreatus in Example 1 and the quinoa powder from Comparative Example 1. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this art or in accordance with the product instructions. Reagents or instruments used without specified manufacturers are all conventional products that can be obtained commercially.

[0046] Quinoa contains nutrients such as protein, total sugar, flavonoids (total flavonoids), and lysine, and has wide applications in food, medicine, and cosmetics. However, most existing research on quinoa focuses on the extraction of nutrients, with limited research on how to increase the content of nutrients (such as total flavonoids and lysine) in quinoa.

[0047] Based on this, a first aspect of the present invention provides a method for preparing fermented quinoa powder with high antioxidant activity, comprising:

[0048] The *Pleurotus ostreatus* strain was inoculated into a solid culture medium at a volume ratio of 8%–10% (V / W) and cultured in the dark to obtain a solid strain.

[0049] The solid strain was inoculated into liquid culture medium at an inoculation rate of 8% to 10% (V / W) and then stirred to obtain Pleurotus ostreatus seed liquid.

[0050] The soaked quinoa was sterilized to obtain quinoa culture medium;

[0051] The seed liquid of Pleurotus ostreatus was inoculated into the quinoa culture medium, and sterile water was added at the same time. After fermentation in the dark, the fermentation product was obtained.

[0052] The fermentation product was freeze-dried, pulverized, and sieved to obtain Golden Top Pleurotus ostreatus fermented quinoa powder.

[0053] The present invention does not impose a specific limitation on the particle size of the fermented quinoa powder obtained after pulverizing and sieving, and the particle size can be selected according to actual needs.

[0054] The present invention provides a method for preparing fermented quinoa powder with high antioxidant activity from *Pleurotus ostreatus*. Specifically, *Pleurotus ostreatus* strain is inoculated into a solid culture medium at an inoculation rate of 8%–10% (V / W) and cultured in the dark to activate the strain and obtain a solid strain. The solid strain is then inoculated into a liquid culture medium at an inoculation rate of 8%–10% (V / W) and cultured with stirring to obtain *Pleurotus ostreatus* seed liquid, which is used for subsequent inoculation of quinoa culture medium. The soaked quinoa is sterilized to obtain a sterile quinoa culture medium, which is beneficial for the subsequent growth of *Pleurotus ostreatus* mycelium in a sterile environment, i.e., in a sterile quinoa culture medium. The *Pleurotus ostreatus* seed liquid is inoculated into the quinoa culture medium, and sterile water is added simultaneously. Fermentation is carried out in the dark to obtain a fermentation product. The fermentation product is freeze-dried, pulverized, and sieved to obtain fermented quinoa powder from *Pleurotus ostreatus*. The method provided by this invention can improve the protein, total sugar, lysine, and total flavonoid content and antioxidant activity of quinoa. The fermented quinoa powder prepared by this method has the advantages of high protein, total sugar, total flavonoid and lysine content, high antioxidant activity, low water holding capacity, low oil holding capacity, high emulsification and high in vitro digestibility.

[0055] In some embodiments, the freeze-drying process includes a pre-freeze-drying process and a main freeze-drying process in sequence;

[0056] In the pre-freeze-drying process, the temperature is -45 to -30°C, and the time is 1 to 3 hours.

[0057] The main freeze-drying process is carried out according to a freeze-drying program, which includes the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth segments executed sequentially. From the first segment to the ninth segment, the temperature is controlled and gradually increased.

[0058] Specifically, the fermentation product is subjected to pre-freeze-drying and main freeze-drying in sequence to obtain freeze-dried fermentation product. Then, the freeze-dried fermentation product is crushed and sieved to obtain Golden Top Pleurotus ostreatus fermented quinoa powder.

[0059] This invention first pre-freeze-dries the fermentation product to make the water in the fermentation product form ice, and then performs the main freeze-drying process according to the freeze-drying procedure to make the ice sublimate into water vapor, thereby achieving efficient freeze-drying. This is beneficial to obtaining Golden Top Pleurotus ostreatus fermented quinoa powder with high protein, total sugar, total flavonoid and lysine content, high antioxidant activity, low water holding capacity, low oil holding capacity, high emulsification and high in vitro digestibility.

[0060] In some implementations, the parameter control of the freeze-drying process is specifically as follows:

[0061] First section: Temperature -52~-48℃, normal pressure, time 4~6h;

[0062] Second section: Temperature -42~-38℃, vacuum degree 22pa, time 2~4h;

[0063] Third section: Temperature -32~-28℃, vacuum degree 22pa, time 4~6h;

[0064] Fourth section: Temperature -20 to -15℃, vacuum degree 22 Pa, time 2 to 5 hours;

[0065] Fifth section: Temperature -12 to -8℃, vacuum degree 22 Pa, time 1 to 3 hours;

[0066] Section 6: Temperature -6 to -2℃, vacuum degree 22 Pa, time 1 to 3 hours;

[0067] Section 7: Temperature 2–6℃, Vacuum 10 Pa, Time 6–10 h;

[0068] Section 8: Temperature 10–20℃, vacuum 10 Pa, time 3–5 h;

[0069] Section 9: Temperature 25-35℃, vacuum 10pa, time 6-10h.

[0070] When the main freeze-drying process is carried out according to the parameters of the above freeze-drying procedure, the ice is fully sublimated into water vapor, achieving more efficient freeze-drying. This results in Golden Top Pleurotus ostreatus fermented quinoa powder with higher protein, total sugar, total flavonoid and lysine content, higher antioxidant activity, lower water holding capacity, lower oil holding capacity, higher emulsification, and higher in vitro digestibility.

[0071] In some embodiments, the sterilization treatment of the soaked quinoa to obtain quinoa culture medium specifically includes: soaking 50-60g of quinoa in water for 10-14h to obtain soaked quinoa, and then sterilizing the soaked quinoa at 110-130℃ for 20-30min to obtain quinoa culture medium.

[0072] The water mentioned above is of a conventional type, such as pure water.

[0073] In some embodiments, the volume-to-mass ratio of the Pleurotus ostreatus seed solution to the quinoa culture medium is (8-10 mL): (50-60 g dry weight).

[0074] In some embodiments, the volume-to-mass ratio of the sterile water to the quinoa culture medium is (8-10 mL): (50-60 g dry weight).

[0075] In some embodiments, the temperature for the light-protected culture is 25–28°C, and the time is 10–12 days.

[0076] Specifically, the *Pleurotus ostreatus* strain was inoculated into a solid culture medium at a volume ratio of 8%–10% (V / W) and cultured in the dark at 25–28°C for 10–12 days to obtain the solid strain.

[0077] In some embodiments, the temperature of the stirred culture is 25-28°C, the rotation speed is 120-150 rpm, and the time is 10-12 days.

[0078] Specifically, the solid strain was inoculated into liquid culture medium at an inoculation rate of 8%–10% V / W, and cultured in the dark for 10–12 days at 25–28°C and 120–150 rpm to obtain Pleurotus ostreatus seed liquid.

[0079] In some embodiments, the light-protected fermentation is carried out at a temperature of 25–28°C for 20–22 days.

[0080] Specifically, the *Pleurotus ostreatus* seed culture is inoculated into the quinoa culture medium, and sterile water is added simultaneously. Fermentation is carried out at 25–28°C in the dark for 10–12 days to obtain the fermentation product. The sterile water, 25–28°C, and dark environment provide the necessary conditions for the growth of *Pleurotus ostreatus* mycelium. During fermentation under these conditions, the *Pleurotus ostreatus* mycelium interacts with the quinoa, thereby yielding the fermentation product.

[0081] In some embodiments, the quinoa is any one of black quinoa, white quinoa, and red quinoa, preferably black quinoa.

[0082] In some embodiments, the solid culture medium is potato dextrose agar medium, and the components and contents of the potato dextrose agar medium are as follows: potato extract powder 12 g / L, glucose 20 g / L, and agar 14 g / L.

[0083] In some embodiments, the liquid culture medium consists of the following components by weight-volume ratio (g / mL): 30% potato juice, 4% glucose, 0.1% potassium dihydrogen phosphate (KH2PO4), 0.1% magnesium sulfate heptahydrate (MgSO4·7H2O), and the remainder is water.

[0084] A second aspect of the present invention provides a fermented quinoa powder with Pleurotus ostreatus, which is prepared by the method described above for preparing fermented quinoa powder with high antioxidant activity. Therefore, this fermented quinoa powder has the advantages of high protein, total sugar, total flavonoid, and lysine content, as well as high antioxidant activity. It also has low water-holding capacity, low oil-holding capacity, high emulsification, and good in vitro digestibility.

[0085] A third aspect of the present invention provides a method for preparing fermented quinoa powder with high antioxidant activity, specifically the fermented quinoa powder obtained from the above-mentioned method, or the application of the above-mentioned fermented quinoa powder in the preparation of protein foods. The inventors have demonstrated that the fermented quinoa powder prepared by this method can be used in the preparation of protein bars.

[0086] A fourth aspect of this invention provides an application of the method for preparing the fermented quinoa powder with high antioxidant activity described above in quinoa cultivation, wherein quinoa is cultivated using the method. Research by the inventors shows that the fermented quinoa powder prepared by this method has significantly higher protein, total sugar, lysine, and total flavonoid content, antioxidant activity, emulsifying properties, and in vitro digestibility than unfermented quinoa, while its water-holding capacity and oil-holding capacity are significantly lower than those of unfermented quinoa. Therefore, this method can be used to cultivate quinoa to increase the protein, total sugar, lysine, and total flavonoid content and antioxidant activity in quinoa.

[0087] The present invention will be further described below through specific embodiments.

[0088] Example 1

[0089] This embodiment provides a method for preparing fermented quinoa powder with high antioxidant activity, including:

[0090] (1) At an inoculation rate of 10% (V / W), the *Pleurotus ostreatus* strain (purchased from Minyuan Edible Fungus Planting Farm, Bayi Township, Wusheng County, strain number "Changbaishan No. 1") was inoculated into potato dextrose agar medium and cultured in the dark at 28°C for 12 days to obtain a solid strain. The components and contents of the potato dextrose agar medium were as follows: potato extract powder 12 g / L, glucose 20 g / L, and agar 14 g / L.

[0091] (2) The solid strain was inoculated into the liquid culture medium at an inoculation rate of 10% (V / W) and cultured at 28℃ and 150 rpm for 12 days to obtain the Pleurotus ostreatus seed liquid; the liquid culture medium was composed of the following components by weight / volume ratio g / mL: 30% potato juice, 4% glucose, 0.1% KH2PO4, 0.1% MgSO4·7H2O, and the remainder was water;

[0092] (3) Soak 55g of black quinoa (purchased from Ganzhou Kangrui Agricultural Products Co., Ltd.) in pure water for 12 hours to obtain soaked black quinoa. Then, sterilize the soaked quinoa at 120℃ for 25 minutes to obtain quinoa culture medium (the dry weight of black quinoa in the quinoa culture medium is 55g).

[0093] (4) Inoculate 10 mL of Pleurotus ostreatus seed liquid into quinoa culture medium, add 10 mL of sterile water, and place in a constant temperature incubator at 28℃ for 22 days of light-protected fermentation to obtain fermentation products.

[0094] (5) The fermentation product is first pre-freeze-dried at -40℃ for 2 hours, and then subjected to main freeze-drying according to the freeze-drying program to obtain the freeze-dried fermentation product; the freeze-dried fermentation product is pulverized and passed through a 60-mesh sieve to obtain Golden Top Pleurotus ostreatus fermented quinoa powder (i.e., fermented quinoa); the freeze-drying program is executed sequentially in the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth sections, with the following parameter control: First section: temperature -50℃, atmospheric pressure, time 5 hours; Second section: temperature Section 1: Temperature -40℃, Vacuum 22 Pa, Time 3h; Section 2: Temperature -30℃, Vacuum 22 Pa, Time 5h; Section 3: Temperature -15℃, Vacuum 22 Pa, Time 4h; Section 4: Temperature -10℃, Vacuum 22 Pa, Time 2h; Section 5: Temperature -5℃, Vacuum 22 Pa, Time 2h; Section 6: Temperature -5℃, Vacuum 22 Pa, Time 2h; Section 7: Temperature 5℃, Vacuum 10 Pa, Time 8h; Section 8: Temperature 15℃, Vacuum 10 Pa, Time 4h; Section 9: Temperature 30℃, Vacuum 10 Pa, Time 8h.

[0095] Example 2

[0096] The preparation method of fermented quinoa powder with high antioxidant activity provided in this embodiment is basically the same as that in Example 1, except that:

[0097] (5) The fermentation product is first pre-freeze-dried at -30℃ for 2 hours, and then subjected to main freeze-drying according to the freeze-drying program to obtain the freeze-dried fermentation product; the freeze-dried fermentation product is pulverized and passed through a 60-mesh sieve to obtain Golden Top Pleurotus ostreatus fermented quinoa powder (i.e., fermented quinoa); the freeze-drying program is executed sequentially in the first, second, third, fourth, fifth, sixth, seventh, eighth and ninth sections, with the following parameter control: First section: temperature -50℃, atmospheric pressure, time 4 hours; Second section: temperature Section 1: Temperature -40℃, Vacuum 22 Pa, Time 3h; Section 2: Temperature -30℃, Vacuum 22 Pa, Time 4h; Section 3: Temperature -20℃, Vacuum 22 Pa, Time 2h; Section 4: Temperature -20℃, Vacuum 22 Pa, Time 2h; Section 5: Temperature -10℃, Vacuum 22 Pa, Time 2h; Section 6: Temperature -2℃, Vacuum 22 Pa, Time 2h; Section 7: Temperature 6℃, Vacuum 10 Pa, Time 6h; Section 8: Temperature 20℃, Vacuum 10 Pa, Time 4h; Section 9: Temperature 25℃, Vacuum 10 Pa, Time 6h.

[0098] Comparative Example 1 (without using Pleurotus ostreatus strain)

[0099] This comparative example provides a method for preparing quinoa flour, including:

[0100] 55g of black quinoa (purchased from Ganzhou Kangrui Agricultural Products Co., Ltd.) was soaked in water for 12 hours to obtain soaked quinoa. Then, the soaked quinoa was sterilized at 120℃ for 25 minutes to obtain quinoa culture medium (the dry weight of black quinoa in the quinoa culture medium was 55g).

[0101] Add 10 mL of sterile water to the quinoa culture medium and incubate in a constant temperature incubator at 28°C for 22 days in the dark to obtain the product;

[0102] The product was first pre-freeze-dried at -40℃ for 2 hours, and then subjected to the main freeze-drying process according to the freeze-drying program. After pulverization, it was passed through a 60-mesh sieve to obtain quinoa powder (i.e., unfermented quinoa). The freeze-drying program consisted of the following steps executed sequentially: Step 1: Temperature -50℃, atmospheric pressure, time 5 hours; Step 2: Temperature -40℃, vacuum degree 22 Pa, time 3 hours. Section 3: Temperature -30℃, Vacuum 22 Pa, Time 5h; Section 4: Temperature -15℃, Vacuum 22 Pa, Time 4h; Section 5: Temperature -10℃, Vacuum 22 Pa, Time 2h; Section 6: Temperature -5℃, Vacuum 22 Pa, Time 2h; Section 7: Temperature 5℃, Vacuum 10 Pa, Time 8h; Section 8: Temperature 15℃, Vacuum 10 Pa, Time 4h; Section 9: Temperature 30℃, Vacuum 10 Pa, Time 8h.

[0103] Comparative Example 2 (Hot Air Drying)

[0104] The preparation method of the fermented quinoa powder with golden top pine mushroom provided in this comparative example is basically the same as that in Example 1, except that:

[0105] (5) Spread the fermentation product on a petri dish and then place it in a hot air drying oven at 55°C for 5 hours to obtain the hot air-dried fermentation product; pulverize the hot air-dried fermentation product and pass it through a 60-mesh sieve to obtain Golden Top Pleurotus ostreatus fermented quinoa powder.

[0106] Application Example 1

[0107] This application example provides a protein bar, comprising the following ingredients by weight: 10 parts of a protein composition (the protein composition is composed of soy protein isolate and whey protein in a mass ratio of 1:1), 10 parts of fermented quinoa powder (fermented quinoa powder prepared according to the method in Example 1), 10 parts of maltitol, 10 parts of polydextrose, 10 parts of wheat flour, 10 parts of berry powder, 15 parts of chocolate, 10 parts of whole milk powder, 4 parts of coconut oil, 3 parts of glycerin, 3 parts of red beet powder, 2 parts of chia seed powder, 2 parts of phospholipids, and 1 part of edible salt.

[0108] The method for preparing protein bars provided in this application example includes the following steps:

[0109] Mix 10 parts of protein composition, 10 parts of fermented quinoa powder, 10 parts of maltitol, 10 parts of polydextrose, 10 parts of wheat flour, 10 parts of berry powder, 15 parts of chocolate, 10 parts of whole milk powder, 4 parts of coconut oil, 3 parts of glycerin, 3 parts of red beet powder, 2 parts of chia seed powder, 2 parts of phospholipids and 1 part of edible salt evenly to prepare a powder.

[0110] Heat 10 parts polydextrose and 10 parts maltitol at 160°C to form a syrup with a sugar content of 85.5 degrees. Add the powder to the syrup with a sugar content of 85.5 degrees and stir evenly to form a mixture.

[0111] The mixture is pressed into shape using a roller press, with the thickness controlled between 5cm and 6cm. It is then cut into strips 12-13cm long and 5-6cm wide, and cooled to room temperature to obtain protein bars.

[0112] Experiment 1

[0113] The fermented quinoa powder from Pleurotus ostreatus in Examples 1-2, the quinoa powder in Comparative Example 1, and the fermented quinoa powder from Pleurotus ostreatus in Comparative Example 2 were used as samples and the following measurements were performed. The results are shown in Table 1.

[0114] Protein: The protein content in the sample was determined according to GB5009.5-2016;

[0115] Total sugar: Total sugar was determined according to the phenol-sulfuric acid method: 25 mL of anhydrous ethanol (mass fraction 80%) was added to 1 g of sample, and the mixture was allowed to stand for 30 min. After centrifugation at 3220 × g for 15 min, the supernatant was discarded, 20 mL of ultrapure water was added, and the mixture was placed in an 80℃ constant temperature water bath for 2 h. After cooling, 1 mL of the supernatant was taken and 0.5 mL of phenol (mass fraction 6%) and 2.5 mL of sulfuric acid were added. After 30 min, the absorbance was measured at 490 nm to obtain the total sugar content.

[0116] Lysine: The lysine content in the sample was determined according to GB 5009.124-2016.

[0117] Table 1 Measurement Results

[0118] project Protein (g / 100g) Total sugar (mg / g) Lysine (g / 100g) Example 1 12.65 7.21 0.83 Example 2 12.87 7.33 0.83 Comparative Example 1 11.37 5.45 0.69 Comparative Example 2 12.43 6.79 0.74

[0119] As shown in Table 1, the protein, total sugar, and lysine content of the fermented quinoa powder from Pleurotus ostreatus in Examples 1-2 were all higher than those in the comparative example. These results demonstrate that the method provided by this invention can effectively increase the protein, total sugar, and lysine content of quinoa, resulting in fermented quinoa powder from Pleurotus ostreatus with high protein, total sugar, and lysine content.

[0120] Experiment 2

[0121] The fermented quinoa powder from Pleurotus ostreatus in Examples 1-2, the quinoa powder in Comparative Example 1, and the fermented quinoa powder from Pleurotus ostreatus in Comparative Example 2 were used as samples and the following measurements were performed. The results are shown in Table 2.

[0122] Total flavonoids: The total flavonoid content in the sample was determined according to the standard SN / T 4592-2016;

[0123] DPPH free radical scavenging rate: The DPPH free radical scavenging rate of the samples was determined according to the method of the Solarbio DPPH free radical scavenging ability test kit purchased.

[0124] Table 2 Measurement Results

[0125] project Total flavonoids (mg RE / g) DPPH free radical scavenging rate (%) Example 1 0.630 50.03 Example 2 0.610 48.71 Comparative Example 1 0.350 25.46 Comparative Example 2 0.504 41.03

[0126] As shown in Table 2, the total flavonoid content and DPPH free radical scavenging rate of the fermented quinoa powder from Pleurotus ostreatus in Examples 1-2 were higher than those in the comparative example. This indicates that the method provided by the present invention can effectively improve the total flavonoid content and antioxidant activity of quinoa, resulting in fermented quinoa powder from Pleurotus ostreatus with high total flavonoid content and high antioxidant activity. This strengthens the scientific value of quinoa as a natural antioxidant and promotes the transformation of quinoa from a traditional grain to a high-value-added functional raw material.

[0127] Experiment 3

[0128] 1. Water-holding capacity test

[0129] The water-holding capacity of the fermented quinoa powder from Example 1 and the quinoa powder from Comparative Example 1 were tested separately: 0.5g of sample was weighed into a centrifuge tube, 1ml of distilled water was added, and the mixture was allowed to stand for 30min. After stirring and shaking, the mixture was centrifuged at 6000r / min for 20min at room temperature. The water on the upper layer of the centrifuge tube was discarded, and the water on the tube wall was absorbed with filter paper. The weight of the centrifuge tube and the precipitate was weighed. The water-holding capacity was calculated according to formula (1):

[0130] Water holding capacity (g / g) = (m3-m2-m1) / m2 Formula (1)

[0131] In the formula, m1 represents the weight of the centrifuge tube, g; m2 represents the mass of the sample weighed, g; and m3 represents the weight of the centrifuge tube and the precipitate, g.

[0132] 2. Oil retention test

[0133] The quinoa powder from Example 1 and the quinoa powder from Comparative Example 1 were used as samples for oil retention tests: A certain amount of sample was weighed into a centrifuge tube, 1 mL of soybean oil was added, stirred, and shaken thoroughly. The mixture was centrifuged at 6000 r / min for 20 min at room temperature. The upper layer of oil in the centrifuge tube was discarded, and the oil on the tube wall was absorbed with filter paper. The weight of the centrifuge tube and the precipitate was weighed. The oil retention was calculated according to formula (2):

[0134] Oil retention (g / g) = (n3-n2-n1) / n2 Formula (2)

[0135] In the formula, n1 represents the weight of the centrifuge tube, g; n2 represents the mass of quinoa weighed, g; and n3 represents the weight of the centrifuge tube and the precipitate, g.

[0136] 3. Emulsification test

[0137] The fermented quinoa powder from Pleurotus ostreatus in Example 1 and the quinoa powder from Comparative Example 1 were used as samples for emulsification tests: The samples were dissolved in distilled water to prepare a quinoa solution with a concentration of 1 mg / mL. Soybean oil was added at an oil ratio of 3:2, and the mixture was sheared at 10000 r / min for 2 min to obtain an emulsion. 100 μL of the emulsion was taken and diluted 50 times (i.e., the dilution factor was 50) with 1 mL of 1% SDS solution (purchased from Sinopharm Chemical Reagent Co., Ltd.). After thorough mixing, the absorbance value A0 was measured at 500 nm using a UV spectrophotometer. The emulsification was calculated according to formula (3):

[0138]

[0139] In the formula, A0 represents the absorbance value at 500 nm; D represents the dilution factor; and C represents the protein concentration in g / mL. 0.01 represents the optical path length.

[0140] Figure 1 The results of water-holding and oil-holding tests are for the fermented quinoa powder from Pleurotus ostreatus in Example 1 and the quinoa powder from Comparative Example 1. Figure 2 The results show the emulsification properties of the fermented quinoa powder from Pleurotus ostreatus in Example 1 and the quinoa powder from Comparative Example 1.

[0141] Depend on Figure 1 and Figure 2 It can be seen that the water-holding and oil-holding properties of the fermented quinoa powder from Pleurotus ostreatus in Example 1 are lower than those of the quinoa powder from Comparative Example 1. The emulsifying properties of the fermented quinoa powder from Pleurotus ostreatus in Example 1 are higher than those of the quinoa powder from Comparative Example 1. This indicates that the fermented quinoa powder from Pleurotus ostreatus in Example 1 has the characteristics of low water-holding, low oil-holding, and high emulsifying properties: Low water-holding makes it easier to form a dry, crispy texture during processing (such as baking, frying, or puffing), making it suitable for developing quinoa chips, cereal bars, biscuits, and other snacks that require a crispy texture; Low oil-holding reduces the amount of oil absorbed during frying or pan-frying, making it suitable as a healthy coating (such as for tempura or fried chicken substitutes), reducing the oil content of the final product and conforming to the trend of low-fat diets; High emulsifying properties indicate that the fermented quinoa powder from Pleurotus ostreatus is easier to emulsify, and has potential application value in fields such as cosmetics.

[0142] Experiment 4

[0143] Artificial saliva, artificial gastric fluid, and artificial intestinal fluid were all purchased from Xinfan Biotechnology Co., Ltd.

[0144] The fermented quinoa powder from Example 1 (using Pleurotus ostreatus) and the quinoa powder from Comparative Example 1 were used as samples for in vitro digestibility testing.

[0145] Dissolve the sample in distilled water to prepare a 5% (w / w) protein solution. Take 500 μL of the protein solution and add 500 μL of artificial saliva (incubated in a 37°C water bath). Mix thoroughly and incubate at 37°C for 5 min to obtain the solution digested with artificial saliva. Add 500 μL of artificial gastric juice (incubated in a 37°C water bath) to the solution digested with artificial saliva, mix thoroughly, and incubate at 37°C for 2 h to obtain the solution digested with both artificial saliva and artificial gastric juice. Add 1000 μL of artificial intestinal juice (incubated in a 37°C water bath) to the solution digested with both artificial saliva and artificial gastric juice, mix thoroughly, and incubate at 37°C for 1 h to obtain the solution digested with artificial saliva. The solutions digested by artificial gastric juice and artificial intestinal juice were collected. The solutions digested by artificial saliva, artificial gastric juice, and artificial intestinal juice were then subjected to enzyme inactivation in a 90℃ water bath for 5 min, centrifuged at 14000×g for 10 min, and the supernatant was collected. The supernatant was then ultrafiltered at 8000g for 5 min. The protein content in the samples (i.e., undigested protein content), the protein content in the solutions digested by artificial saliva and artificial gastric juice (i.e., gastric digested protein content), and the protein content in the solutions digested by artificial saliva, artificial gastric juice, and artificial intestinal juice (i.e., intestinal digested protein content) were measured. The digestibility was calculated based on the protein content before and after digestion. The results are shown in Table 3.

[0146] Simulated gastric digestibility (%) = (undigested protein content - digested protein content) / undigested protein content × 100%;

[0147] Simulated intestinal digestibility (%) = (undigested protein content - digested protein content) / undigested protein content × 100%.

[0148] Table 3 Measurement Results

[0149] project Simulated gastric digestion rate (%) Simulated intestinal digestibility (%) Example 1 40 74.67 Comparative Example 1 26.67 61.33

[0150] High in vitro digestibility is beneficial for improving the utilization rate of nutrients in quinoa. As shown in Table 3, the simulated gastric digestibility and simulated intestinal digestibility of the fermented quinoa powder with Pleurotus ostreatus in Example 1 are both higher than those of the quinoa powder in Comparative Example 1, which indicates that the in vitro digestibility of fermented quinoa (i.e., the fermented quinoa powder with Pleurotus ostreatus in Example 1) is higher than that of the quinoa powder in Comparative Example 1.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a fermented quinoa flour of Pleurotus eryngii with high antioxidant activity, characterized by, The method comprises the following steps: The inoculation amount of Pleurotus eryngii var. citrinopileatus is 8%-10% (V / W), and the solid culture medium is cultured at 25-28°C in the dark for 10-12 days to obtain a solid strain; The inoculation amount of the solid strain is 8%-10% (V / W), and the liquid culture medium is stirred and cultured at 25-28°C and 120-150 rpm for 10-12 days to obtain a seed liquid of Pleurotus eryngii var. citrinopileatus; 50-60 g of quinoa is soaked in water for 10-14 hours to obtain soaked quinoa, and then the soaked quinoa is sterilized at 110-130°C for 20-30 minutes to obtain a quinoa culture medium; The seed liquid of Pleurotus eryngii var. citrinopileatus is inoculated into the quinoa culture medium, and sterile water is added, and then the mixture is fermented at 25-28°C in the dark for 20-22 days to obtain a fermentation product; wherein the volume-to-mass ratio of the seed liquid of Pleurotus eryngii var. citrinopileatus to the quinoa culture medium is (8-10 mL) : (50-60 g dry weight), and the volume-to-mass ratio of the sterile water to the quinoa culture medium is (8-10 mL) : (50-60 g dry weight) ; The fermentation product is subjected to freeze-drying treatment, and after being crushed and sieved, a Pleurotus eryngii var. citrinopileatus fermented quinoa powder is obtained; The freeze-drying treatment comprises pre-freeze-drying treatment and main freeze-drying treatment in sequence; In the pre-freeze-drying treatment, the temperature is -45 to -30°C, and the time is 1-3 hours; The main freeze-drying treatment is performed according to a freeze-drying program, and the freeze-drying program comprises first to ninth sections which are executed in sequence, and the temperature is controlled and gradually increased from the first section to the ninth section; the parameters of the freeze-drying program are controlled as follows: The first section: temperature -52 to -48°C, normal pressure, time 4-6 hours; The second section: temperature -42 to -38°C, vacuum degree 22 pa, time 2-4 hours; The third section: temperature -32 to -28°C, vacuum degree 22 pa, time 4-6 hours; The fourth section: temperature -20 to -15°C, vacuum degree 22 pa, time 2-5 hours; The fifth section: temperature -12 to -8°C, vacuum degree 22 pa, time 1-3 hours; The sixth section: temperature -6 to -2°C, vacuum degree 22 pa, time 1-3 hours; The seventh section: temperature 2-6°C, vacuum degree 10 pa, time 6-10 hours; The eighth section: temperature 10-20°C, vacuum degree 10 pa, time 3-5 hours; The ninth section: temperature 25-35°C, vacuum degree 10 pa, time 6-10 hours.

2. The method for preparing fermented quinoa powder with high antioxidant activity according to claim 1, characterized in that, The quinoa is any one of black quinoa, white quinoa and red quinoa; And / or, the solid culture medium is a potato glucose agar culture medium, and the components and contents of the potato glucose agar culture medium are as follows: potato extract powder 12 g / L, glucose 20 g / L, and agar 14 g / L; And / or, the liquid culture medium consists of the following components by weight volume ratio g / mL: potato juice 30%, glucose 4%, KH2PO4 0.1%, MgSO4·7H2O 0.1%, and the rest is water.

3. A fermented quinoa flour of Tremella aurantialba, characterized in that, The fermented quinoa powder of the Tricholoma giognenense is prepared by the method of claim 1 or 2.

4. Use of the fermented quinoa powder of the Tricholoma giognenense of claim 3 in the preparation of a protein food.

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