Method for solid-state fermentation of wheat germs by using lucid ganoderma

Abstract

The invention belongs to the field of novel agricultural products, and provides a method for solid-state fermentation of wheat germs with lucid ganoderma, which comprises the following steps: firstly, preparing a lucid ganoderma liquid strain; secondly, constructing a proper wheat germ solid state fermentation system; and finally, inoculating and regulating fermentation conditions, so that the ganoderma lucidum mycelia are effectively colonized and grow in the substrate, and finally, a mycelium-enriched wheat germ product is obtained. The health-care characteristics of the lucid ganoderma and the basic nutrition of the wheat germs are combined, so that the product contains various nutritional ingredients and active substances and is easily digested and absorbed by a human body, 14.1-79.14 mg / g of polypeptide, 78.6-100.9 mg / g of polysaccharide and 0.37-0.52 mg of GAE / g total phenols can be generated by solid-state fermentation of the wheat germs for 7-18 days through the lucid ganoderma, and the effects of reducing the rough taste of the wheat germs, improving the immunity of the wheat germs and improving the health-care effect of the wheat germs are achieved. The stability of the wheat germ is improved while the palatability of the product is improved, the fat content is reduced to 1.16 g / 100g, and the method has good development and application prospects.

Description

Technical Field

[0001] This invention belongs to the field of new agricultural products, and specifically relates to a method for solid-state fermentation of wheat germ from Ganoderma lucidum. Background Technology

[0002] Wheat germ, a byproduct of wheat milling, is rich in protein, carbohydrates, fat, dietary fiber, and various bioactive substances such as flavonoids and polyphenols, making it the most nutritious part of wheat. In China, the annual production of wheat germ exceeds 2 million tons, indicating significant potential for development and utilization. The utilization of wheat germ mainly focuses on four aspects: first, mixing it into wheat bran for sale as animal feed; second, using it as a natural nutritional ingredient in food processing to enhance the aroma and flavor of products, and also in the production of food powders and nutritional supplements; third, using it to produce wheat germ oil and wheat germ protein, with relatively mature products already available on the market; and fourth, preparing active peptides from wheat germ, a process still in its early stages.

[0003] Wheat germ, with its abundant carbon source and relatively loose structure, serves as an excellent substrate for microbial solid-state fermentation. Solid-state fermentation refers to a fermentation process involving a solid substrate, carried out in the absence of or with minimal free water. This technology has a history of thousands of years in my country and boasts advantages such as low cost, mild conditions, high productivity per unit volume, and low wastewater discharge. Filamentous fungi are currently the main microbial species used in solid-state fermentation. In the life cycle of filamentous fungi, hyphae can function as both a nutrient source (absorbing nutrients and excreting metabolic products) and a reproductive source (completing their life cycle). Throughout the solid-state fermentation process, hyphal growth is accompanied by the secretion of various enzymes, which can alter the properties of the solid substrate and release bioactive substances, giving the entire fermentation process a "two-way" nature. Patent application CN117243333A utilizes lactic acid bacteria and yeast in synergy with neutral proteases to produce fortified wheat germ. However, the growth of yeast and lactic acid bacteria in a solid substrate primarily involves increasing cell number and adsorption onto the solid substrate surface, with limited ability to produce hydrolytic enzymes, thus limiting the utilization of the solid substrate.

[0004] Reishi mushroom is a precious traditional Chinese medicine that has been used in my country and other Asian countries for thousands of years to promote health, prolong life, and prevent disease. The fruiting body of Reishi is formed by highly intertwined mycelium, therefore the nutritional value and active ingredients of the mycelium are highly similar to those of the fruiting body. During fermentation, the Reishi mycelium not only does not produce any toxic or harmful substances, but its metabolites also possess antioxidant, blood pressure-lowering, and cholesterol-lowering physiological activities. Reishi was included in the list of substances traditionally considered both food and medicinal materials in 2023. It possesses a complex and powerful hydrolytic enzyme system, and its potential for decomposition and anabolism can be used to improve the processing and nutritional properties of grains. Patent application CN102172274A uses rice as the main fermentation substrate, allowing Reishi mycelium to grow within the rice through solid-state fermentation, resulting in rice rich in Reishi mycelium. From a nutritional perspective, rice, as a representative of staple food, is mainly composed of starch and a small amount of protein. Compared with fortified foods such as wheat germ, rice lacks vitamins, minerals, dietary fiber, and bioactive substances, resulting in very low nutritional value. The upper limit of nutritional improvement after solid-state fermentation of Ganoderma lucidum is relatively low.

[0005] Therefore, the inventors' research direction has become whether they can better combine Ganoderma lucidum and wheat germ to obtain high-value-added agricultural products. Summary of the Invention

[0006] This invention addresses the problems existing in the aforementioned technologies by providing a method for solid-state fermentation of wheat germ using Ganoderma lucidum. First, a liquid inoculum of Ganoderma lucidum is prepared; second, a suitable solid-state fermentation system for wheat germ is constructed; finally, inoculation and control of fermentation conditions are performed to allow Ganoderma lucidum mycelium to effectively colonize and grow in the substrate, ultimately yielding a wheat germ product enriched with mycelium. This invention combines the health benefits of Ganoderma lucidum with the basic nutrients of wheat germ to create a novel functional food ingredient, resulting in a product containing multiple nutrients and active substances that are easily digested and absorbed by the human body. Solid-state fermentation of wheat germ with Ganoderma lucidum for 7-18 days can produce 14.1-79.14 mg / g polypeptides, 78.6-100.9 mg / g polysaccharides, and 0.37-0.52 mg GAE / g total phenols, etc. Solid-state fermentation of Ganoderma lucidum reduces the rough texture of wheat germ, improves the palatability of the product, and enhances the stability of wheat germ, while reducing the fat content to 1.16 g / 100g. The in vitro ACE inhibition rate, cholesterol micelle solubility inhibition rate, and DPPH clearance rate of fermented wheat germ by Ganoderma lucidum were increased by 1.16 times, 3.6 times, and 4.47 times, respectively, showing good prospects for development and application.

[0007] Compared to the prior art CN117243333A, which utilizes lactic acid bacteria and yeast in synergistic neutral protease production of fortified wheat germ, the Ganoderma lucidum used in this application possesses a complex enzyme system, making it more compatible with solid-state fermentation of wheat germ and resulting in higher fermentation capacity. In a solid substrate, the growth patterns of filamentous fungi like Ganoderma lucidum differ fundamentally from those of yeast and lactic acid bacteria. Filamentous fungi exhibit apical growth; during growth, not only do hyphae extend and branch, but in the later stages of development, hyphae come into contact with each other, leading to localized degradation of the hyphal walls at the contact points and the formation of hyphal networks. During this process, the hyphae intertwine with the nutrient carrier substrate, forming a difficult-to-separate mixture, while simultaneously hydrolyzing the substrate to a greater extent to release bioactive substances. Therefore, the solid-state fermentation of wheat germ using filamentous fungi in this application demonstrates a higher degree of compatibility and advantages.

[0008] Meanwhile, the growth process of Ganoderma lucidum mycelium exhibits a substrate-induced effect, meaning that the components of the solid-state fermentation medium directly induce the secretion of enzymes in Ganoderma lucidum mycelium, thereby affecting its physiological and biochemical activities. Rice is a starch-rich raw material, and the hydrolytic enzyme secreted by Ganoderma lucidum mycelium is mainly amylase. Hydrolyzing starch provides carbon and nitrogen sources for the vegetative growth stage of Ganoderma lucidum mycelium. However, the limited nutrient composition of rice severely affects the synthesis of secondary metabolites such as ganoderic acids and polysaccharides during the secondary metabolic stage of Ganoderma lucidum mycelium. Wheat germ, the component of this application, is a component with extremely high nutrient density. While providing a sufficient material basis for the synthesis of secondary metabolites from Ganoderma lucidum mycelium, it also fully mobilizes the complex and powerful hydrolytic enzyme system of Ganoderma lucidum. In the early stage of Ganoderma lucidum mycelium growth, amylase, lipase, and protease are the main enzymes used to rapidly obtain carbon and nitrogen sources. In the middle and later stages, under the action of lignocellulose-degrading enzymes, the release of lignocellulose degradation products in wheat germ, such as phenolic substances, is promoted, which can stimulate the synthesis of secondary metabolites from Ganoderma lucidum. Therefore, wheat germ is more suitable for the solid-state fermentation system of Ganoderma lucidum in this application than staple food substrates such as rice.

[0009] The fruiting body of Ganoderma lucidum is formed by highly intertwined mycelium, and the chemical composition and active ingredients of the mycelium are highly similar to those of the fruiting body. Furthermore, Ganoderma lucidum mycelium has a very low degree of lignification and chitin content, making it easily digestible and absorbable by the human body. The inventors also discovered that by using solid-state fermentation and employing a strictly sterilized fermentation substrate, interference from other microorganisms can be largely eliminated during the fermentation process. This method is easier to control than liquid fermentation and has lower design requirements and costs for the biochemical reactor. The entire production process consists of three stages: preparing liquid Ganoderma lucidum spawn; preparing wheat germ solid-state fermentation medium; and inoculation and fermentation. All three stages can be automated, reducing labor costs.

[0010] Based on the above inventive concept, the specific technical solution of this application is as follows: A method for solid-state fermentation of wheat germ with Ganoderma lucidum, using wheat germ as the fermentation substrate, allows Ganoderma lucidum mycelium to grow within the wheat germ through solid-state fermentation, yielding wheat germ rich in Ganoderma lucidum mycelium; further comprising the following steps: (1) After activating the Ganoderma lucidum slant culture, inoculate it into potato glucose liquid culture medium and culture it for a certain period of time to obtain Ganoderma lucidum liquid culture. (2) Wheat germ is placed into a fermentation container and sterilized at 121℃ for 30-45 minutes. After sterilization, it is mixed with sterile water to obtain wheat germ solid fermentation culture medium. (3) Inoculate a certain amount of Ganoderma lucidum liquid culture into the wheat germ solid fermentation medium prepared in step (2), and culture it in the dark to obtain Ganoderma lucidum solid fermented wheat germ.

[0011] The strains described in this invention can be Ganoderma lucidum strains from various sources. In the verification of this invention, Ganoderma lucidum No. 5 from the Taian Branch of Shandong Academy of Agricultural Sciences was used, but other Ganoderma lucidum strains can also be selected.

[0012] Preferably, the activation process of the bacterial strain in step (1) is as follows: Using a sterile inoculation needle, the Ganoderma lucidum culture was picked up from the slant culture medium and transferred to a PDA medium plate for activation. After culturing at 25-28 °C for 7 days, it was transferred to a new plate and cultured under the same conditions. Then, using a sterile punch, a mycelial block with a diameter of 9 mm and a thickness of about 2 mm was made on the same circumference of the plate that was already covered with mycelium. One of the above mycelial blocks was inoculated on a PDA medium plate, placed in the center of the medium plate, sealed with sealing film, and incubated in the dark at 25-28 °C for 7 days.

[0013] Preferably, the method for preparing Ganoderma lucidum liquid culture in step (1) is as follows: select activated Ganoderma lucidum culture in good growth condition, punch holes at the edge of the hyphae to obtain a 4 mm inner diameter block, pick up 5 to 6 blocks with an inoculation needle, inoculate them into 100 mL of potato dextrose liquid culture medium, and culture them in the dark with shaking at 150 r / min; the culture temperature of Ganoderma lucidum liquid culture is 25 to 28 ℃, and the culture time is 7 to 10 days.

[0014] Preferably, the wheat germ solid fermentation medium in step (2) uses uncrushed wheat germ, which is separated from the bran milling material by a purifier during the wheat flour processing, and has a natural pH.

[0015] Preferably, the mass ratio of wheat germ to sterile water in step (2) is 1:0.7 to 1:1.1.

[0016] In the preferred step (3), 10% to 30% of the wheat germ weight is inoculated with Ganoderma lucidum liquid culture; the fermentation temperature is 25℃ to 30℃, and the culture time is 7 to 18 days.

[0017] In existing technologies, the natural bitterness and rough texture of wheat germ affect its palatability, resulting in limited practical applications of wheat germ in food processing. Furthermore, fresh wheat germ is prone to spoilage and deterioration, and its short shelf life restricts its use in the food industry. To address these issues, the inventors have provided the aforementioned process utilizing Ganoderma lucidum for solid-state fermentation. This not only solves the problems of wheat germ's food processing and utilization but also enhances the nutritional value of the wheat germ itself. This invention demonstrates that solid-state fermentation of wheat germ using Ganoderma lucidum is a feasible, safe, and efficient method for obtaining low-cost, high-nutrient fermented grains.

[0018] The beneficial effects of the present invention include at least the following: Ganoderma lucidum solid-state fermented wheat germ is made by solid-state fermentation of wheat germ, catering to the Chinese people's preference for grains. Through fermentation, the medicinal effects of Ganoderma lucidum and the nutrients of wheat germ can be organically combined, resulting in Ganoderma lucidum fermented wheat germ containing a variety of nutrients and functional components; more specifically: (1) In the solid-state fermented wheat germ prepared by the present invention, the soluble protein content reached a maximum of 91.74 mg / g on the 14th day of fermentation, which was 2.66 times higher than that of unfermented wheat germ; the polypeptide content reached a maximum of 79.14 mg / g on the 15th day of fermentation, which was 31.02 times higher than that of unfermented wheat germ; and the amino acid nitrogen content was 73.3 mg / g on the 16th day of fermentation, which was 8.02 times higher.

[0019] (2) In the solid fermented wheat germ prepared by the present invention, the polysaccharide content reached a maximum of 100.9 mg / g on the 11th day of fermentation, which was 63.5% higher than that of unfermented wheat germ.

[0020] (3) The solid fermentation of wheat germ prepared by the present invention reduces the lignocellulose content and fat content. While reducing the rough taste of wheat germ and improving the palatability of the product, it also improves the stability of wheat germ. The fat content reaches the minimum level of 1.16 g / 100g on the 14th to 18th day of fermentation, and the fat content decreases by 90.68% after fermentation.

[0021] (4) In the solid fermented wheat germ prepared by the present invention, the triterpenoid content reached a maximum of 4.75 mg / g on the 7th day of fermentation, which was 126% higher than that of unfermented wheat germ; the total phenol content reached a maximum of 0.52 (mg GAE / g) on ​​the 16th day of fermentation, which was 40.5% higher than that of unfermented wheat germ.

[0022] In addition, the in vitro antihypertensive, cholesterol-lowering, and antioxidant effects of the Ganoderma lucidum solid-state fermented wheat germ prepared by this invention are significantly improved, achieving the goal of high-value utilization, specifically reflected in: (1) The in vitro ACE inhibition rate of the solid fermented wheat germ water extract of Ganoderma lucidum prepared in this invention reached a maximum of 39.8% on the 7th day of fermentation, which was 1.16 times higher than that of unfermented wheat germ.

[0023] (2) The in vitro cholesterol micelle solubility inhibition rate of the water extract of Ganoderma lucidum solid fermentation wheat germ prepared by the present invention reached a maximum of 50.67% on the 15th day of fermentation, and the alcohol extract reached a maximum of 56.6% on the 13th day of fermentation. Compared with unfermented wheat germ, the in vitro cholesterol micelle solubility inhibition rate was increased by 2.4 times and 3.6 times, respectively. (3) The in vitro DPPH scavenging rate of the water extract of Ganoderma lucidum solid fermentation wheat germ prepared by the present invention reached a maximum of 37.1% on the 9th day of fermentation, and the alcohol extract reached a maximum of 41.6% on the 12th day of fermentation. Compared with unfermented wheat germ, the in vitro DPPH scavenging rates were increased by 1.37 times and 4.47 times, respectively. Attached Figure Description

[0024] Figure 1 This is an example of the mycelial growth of Ganoderma lucidum during solid-state fermentation in an embodiment of the present invention (A is a top view of Ganoderma lucidum fermenting wheat germ during solid-state fermentation; B is a side view of Ganoderma lucidum fermenting wheat germ during solid-state fermentation). Figure 2 This illustrates the changes in biomass and respiration intensity of Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Figure 3 This illustrates the changes in protease activity of Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Figure 4 This illustrates the changes in fat content of Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Figure 5 This illustrates the changes in polysaccharides in Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Figure 6 This invention illustrates the changes in polypeptides, soluble proteins, and amino acid nitrogen during solid-state fermentation of Ganoderma lucidum in this embodiment of the invention. Figure 7 This illustrates the changes in triterpenes of Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Figure 8 This illustrates the change in total phenols in Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Figure 9 This illustrates the change in ACE inhibition rate of Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Figure 10This illustrates the change in cholesterol micelle solubility inhibition rate of Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Figure 11 This illustrates the change in DPPH free radical scavenging rate of Ganoderma lucidum during solid-state fermentation in this embodiment of the invention. Detailed Implementation

[0025] The following detailed embodiments further illustrate the above-described content of the present invention, but should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Unless otherwise specified, the following embodiments are all implemented using conventional prior art. Unless otherwise specified, all percentages below are weight percentages.

[0026] In the following examples, the production of Ganoderma lucidum liquid culture was carried out in strict accordance with aseptic operating procedures; The PDA solid plate culture medium used had the following composition: 200g potato, 20g glucose, 1L water, 20g agar, and natural pH. Peeled potatoes were cut into chunks and boiled for 20 minutes. The mixture was then filtered through eight layers of gauze, and glucose and agar were added. The mixture was heated until the agar dissolved. After cooling, water was added to a final volume of 1L, and the mixture was dispensed and sterilized at 121°C for 20 minutes.

[0027] Potato glucose liquid culture medium is composed of the following ingredients: 200g potatoes, 20g glucose, 1L water, and natural pH. Peel and cut the potatoes into chunks, boil for 20 minutes, then filter through eight layers of gauze and add glucose. After cooling, add water to a final volume of 1L, dispense into 250mL Erlenmeyer flasks, seal with sealing film, and sterilize at 121°C for 20 minutes.

[0028] The wheat germ used is separated from the wheat flour by a purifier during the wheat flour processing, and has a natural pH.

[0029] The Ganoderma strain used in the following examples is Ganoderma lucidum NO.5 from the Taian Branch of Shandong Academy of Agricultural Sciences.

[0030] Example 1: A method for solid-state fermentation of wheat germ with Ganoderma lucidum, comprising the following steps: (1) Using a sterile inoculation needle, the Ganoderma lucidum strain preserved on the slant culture medium was picked up and transferred to a PDA medium plate for activation. It was then cultured at 25-28℃ for 7 days, and then transferred to a new plate. After culturing under the same conditions, a mycelial block with a diameter of 9 mm and a thickness of approximately 2 mm was created on the same circumference of the plate with mycelium growth using a sterile punch. One mycelial block was inoculated onto a PDA medium plate, placed in the center of the plate, sealed with sealing film, and incubated in the dark at 25-28℃ for 7 days.

[0031] Select activated Ganoderma lucidum strains in good growth condition, make holes at the edge of the mycelium and take 6 mycelial blocks with a diameter of 4 mm. Inoculate them into 250 mL Erlenmeyer flasks containing 100 mL of potato dextrose liquid culture medium. Incubate at 26℃ and 150 r / min in the dark for 8 days to obtain Ganoderma lucidum liquid culture medium.

[0032] (2) Take 20g of wheat germ and put it into a 450mL glass bottle. Sterilize at 121℃ for 30min. After sterilization, add 18mL of sterile water and mix well to obtain wheat germ solid fermentation culture medium.

[0033] (3) Each bottle of wheat germ was inoculated with 4 mL of Ganoderma lucidum liquid culture and cultured at 26℃ in the dark for 18 days to obtain solid fermented wheat germ of Ganoderma lucidum.

[0034] Example 2: Detection of mycelial growth during Ganoderma lucidum solid-state fermentation and wheat germ fermentation In Example 1, the growth of Ganoderma lucidum during solid-state fermentation was examined, including biomass, respiration intensity, and protease activity. The results are as follows: Figure 1-3 As shown: During fermentation, the morphological changes of Ganoderma lucidum are as follows: Figure 1 As shown. From day 0 to day 8, the mycelium grows rapidly. By day 8, the mycelium covers the surface of the wheat germ culture medium and begins to penetrate its interior, but the mycelium is weak and scarce. From day 8 to day 10, the number of mycelium increases further, gradually becoming thicker and completely penetrating the wheat germ culture medium; the mycelium is white and dense. From day 10 to day 14, the surface and interior of the wheat germ culture medium are completely covered and penetrated by the mycelium. As fermentation continues, the mycelium enters the aging stage on day 16, and yellow droplets and drying appear on the surface of the fermentation substrate.

[0035] Biomass is a fundamental parameter characterizing the growth status of microorganisms. The end products of biological reaction processes can be divided into two categories: organisms and metabolic products. Glucosamine is a special substance in fungal cells and is not present in wheat germ. Therefore, the experiment predicts biomass by measuring glucosamine content, while simultaneously measuring the respiration intensity during fermentation reflects the metabolic level of Ganoderma lucidum. Figure 2It can be seen that glucosamine showed a phased increasing trend with increasing fermentation time, indicating that Ganoderma lucidum mycelium mainly has three developmental stages during growth. In the early stage of fermentation, mycelial biomass growth is relatively rapid, while in the later stage, mycelial growth is slow and the biomass change level is low. During fermentation, the respiration intensity of mycelium also showed a phased increasing trend, reaching a maximum of 643.2 (uL / (g·h)) at 11 days, and remaining basically stable from 8 to 18 days, indicating good mycelial growth.

[0036] Regarding Ganoderma lucidum mycelium, the activities of different types of proteases secreted during solid-state fermentation change with the growth stage. Studying the changes in the activities of different protease types can reflect the pattern of target peptide content changes over time, helping to analyze and determine the time point of peptide accumulation in fermented wheat germ. Using wheat germ as a substrate at 26°C, the changes in protease types and activities during solid-state fermentation of Ganoderma lucidum mycelium are shown below. Figure 3 As shown, during the solid-state fermentation of Ganoderma lucidum, the activities of all three proteases were below 100 U / g from 0 to 7 days. From 8 to 12 days, with the extension of fermentation time, the activities of the three proteases increased significantly. The activities of acidic and neutral proteases were basically at the same level, consistently higher than the activity of alkaline protease. From 13 to 18 days, the activity of neutral protease increased rapidly, with an enzyme activity level much higher than that of acidic and alkaline proteases, reaching a maximum value (658.4 U / g) on ​​16 days. The activities of acidic and alkaline proteases showed a trend of first increasing and then decreasing. The activity of acidic protease reached its maximum value (468.4 U / g) on ​​15 days. The activity of alkaline protease reached its maximum value (269.1 U / g) on ​​16 days. Monitoring the protease activities indicates that the degradation of wheat germ protein by Ganoderma lucidum during fermentation is mainly carried out by acidic and neutral proteases. At the same time, the protease activity also indirectly reflects the physiological and biochemical state of Ganoderma lucidum.

[0037] Example 3: Detection of nutrient components during Ganoderma lucidum solid-state fermentation and wheat germ fermentation The nutritional components of the Ganoderma lucidum solid-state fermented wheat germ prepared in Example 1 were tested, and the results are as follows: Figure 4 - As shown in 6.

[0038] Changes in fat during wheat germ fermentation, such as Figure 4 As shown, the fat content decreased significantly during fermentation, exhibiting a step-like decline. The fat content of unfermented wheat germ was 12.18 g / 100g; the fat content reached its minimum level of 1.16 g / 100g during days 14-18 of fermentation. The fat content decreased by 90.68% after fermentation, likely because the acids and enzymes produced during fermentation degraded the fat, converting large molecules into smaller molecules such as short-chain fatty acids, thus reducing its content.

[0039] Changes in polysaccharide content during wheat germ fermentation, such as Figure 5 As shown, the crude polysaccharides in fermented wheat germ include extracellular polysaccharides and Ganoderma lucidum mycelium polysaccharides. The polysaccharide content showed a trend of first increasing and then decreasing. The polysaccharide content of unfermented wheat germ was 40.44 mg / g; it reached a maximum of 100.9 mg / g on the 11th day of fermentation, which was 63.5% higher than that of unfermented wheat germ.

[0040] The soluble protein content, polypeptide content, and amino acid nitrogen content during wheat germ fermentation are as follows: Figure 6 As shown in the figure, the soluble protein content increased during fermentation from 0 to 14 days; from 14 to 18 days, the soluble protein content decreased slowly. The soluble protein content of unfermented wheat germ was 25.04 mg / g, reaching a maximum of 91.74 mg / g on day 14, which was 2.66 times higher than that of unfermented wheat germ. The polypeptide content of unfermented wheat germ was 2.77 mg / g. During the early stage of mycelial development (0-4 days), protease activity was low, so the polypeptide content and soluble protein content only increased slightly. During fermentation from 4 to 14 days, as the mycelium grew, protease activity gradually increased, causing the proteins in the wheat germ to be broken down into polypeptides and lower molecular weight proteins, thereby improving protein solubility and ultimately increasing the soluble protein content. The polypeptide content reached a maximum of 79.14 mg / g on day 15, which was 31.04 times higher than that of unfermented wheat germ. During fermentation for 14-18 days, the soluble protein content in wheat germ slowly decreased. This is likely because, to maintain its own growth, the mycelium consumes soluble proteins, which gradually decompose into smaller polypeptides and amino acids with various aromas. Amino acid nitrogen refers to the content of nitrogen in the form of amino acids and can be used to determine the degree of fermentation. The graph shows that amino acid nitrogen exhibits a continuous upward trend, increasing significantly with prolonged fermentation time. The amino acid nitrogen content of unfermented wheat germ was 8.12 mg / g, while that of wheat germ fermented for 16 days was 73.3 mg / g, an increase of 8.02 times. A downward trend appeared from days 17-18, possibly due to the dissimilatory process of the mycelium consuming free amino acids in the substrate.

[0041] Example 4: Detection of active ingredients during Ganoderma lucidum solid-state fermentation and wheat germ fermentation The changes in the content of triterpenes and total phenols of Ganoderma lucidum during solid-state fermentation in Example 1 were detected, and the results are as follows: Figure 7 and Figure 8 As shown.

[0042] Ganoderma triterpenes are the main secondary metabolites in Ganoderma lucidum and possess various biological activities. The effects of Ganoderma lucidum fermentation on triterpenoid compounds in wheat germ are as follows: Figure 7As shown, the content of triterpenoids in wheat germ gradually increased during fermentation from 0 to 7 days, reaching a maximum of 4.75 mg / g on day 7, which was 126% higher than that in unfermented wheat germ. The triterpenoid content decreased from 8 to 18 days, possibly due to the transformation or decomposition of triterpenoids by the mycelium.

[0043] Wheat germ contains a large amount of total phenolic antioxidants, mainly existing in free, soluble esterified, and insoluble bound forms. However, the content of free phenolic compounds in wheat germ is relatively low. Solid-state fermentation of Ganoderma lucidum can effectively release phenolic compounds bound to starch, protein, and other substances from wheat germ, thereby significantly enhancing the antioxidant effect. The effect of Ganoderma lucidum solid-state fermentation on the total phenolic content of wheat germ is as follows: Figure 8 As shown, during the solid-state fermentation of Ganoderma lucidum, the total phenol content showed a trend of first increasing and then decreasing, reaching a maximum of 0.52 (mg GAE / g) on ​​day 16, which was 40.5% higher than that of unfermented wheat germ. From day 8 to 16, due to the breakdown of covalent bonds between phenolic compounds and other structures in wheat germ by metabolic enzymes such as proteases produced during Ganoderma lucidum fermentation, some phenolic compounds were released from the wheat germ and converted into free phenols.

[0044] Example 5: Performance Testing of Wheat Germ Fermented from Ganoderma Lucidum In Example 1, the changes in the in vitro ACE inhibition rate, cholesterol micelle solubility inhibition rate, and DPPH scavenging rate of wheat germ extract during Ganoderma lucidum solid-state fermentation were detected, and the results are as follows: Figure 9-11 As shown.

[0045] During the solid-state fermentation of Ganoderma lucidum, the in vitro ACE inhibition rate of wheat germ aqueous extract showed a trend of first increasing and then decreasing, reaching a maximum of 39.8% on day 7, which was 1.16 times higher than that of unfermented wheat germ. The in vitro cholesterol inhibition rate of wheat germ aqueous extract reached a maximum of 50.67% on day 15, and that of the ethanol extract reached a maximum of 56.6% on day 13, representing increases of 2.4 times and 3.6 times, respectively, compared to unfermented wheat germ. The in vitro DPPH scavenging rate of wheat germ aqueous extract reached a maximum of 37.1% on day 9, and that of the ethanol extract reached a maximum of 41.6% on day 12, representing increases of 1.37 times and 4.47 times, respectively, compared to unfermented wheat germ. Functional active substances such as polypeptides, polysaccharides, and triterpenes played important roles in lowering blood pressure, lowering cholesterol, and antioxidation. With the growth of mycelium, a large number of functional active substances were produced under the action of Ganoderma lucidum enzymes and mycelial metabolism, significantly enhancing the functionality of solid-state fermented wheat germ.

[0046] In summary, the fermentation process of wheat germ in this invention is simple, the fermentation product is rich in antioxidants, blood pressure lowering, and cholesterol lowering components, the bioavailability of nutrients is high, the preparation method is simple, the raw materials are inexpensive, and it is easy to industrialize, thus having good practical value and potential for promotion.

[0047] The above embodiments are merely one specific implementation method selected by the present invention. Therefore, the application of the present invention is not limited to the examples above. Ordinary changes and substitutions made by those skilled in the art within the scope of this technical solution should fall within the protection scope of the claims of the present invention.

Claims

1. A method for solid-state fermentation of wheat germ with Ganoderma lucidum, characterized in that, Includes the following steps: (1) After activating the Ganoderma lucidum slant culture, inoculate it into potato glucose liquid culture medium and culture it for a certain period of time to obtain Ganoderma lucidum liquid culture. (2) Wheat germ is placed into a fermentation container and sterilized at 121℃ for 30-45 minutes. After sterilization, it is mixed with sterile water to obtain wheat germ solid fermentation culture medium. (3) Inoculate a certain amount of Ganoderma lucidum liquid culture into the wheat germ solid fermentation medium prepared in step (2), and culture it in the dark to obtain Ganoderma lucidum solid fermented wheat germ.

2. The method for solid-state fermentation of wheat germ with Ganoderma lucidum according to claim 1, characterized in that, The activation process of the strain in step (1) is as follows: the strain preserved on the slant is picked out from the slant culture medium with a sterile inoculation needle and transferred to a PDA culture medium plate for activation. It is then cultured at 25-28 ℃ for 7 days and then transferred to a new plate. After culturing under the same conditions, a mycelial block with a diameter of 9 mm and a thickness of 2 mm is made on the same circumference of the plate that has been covered with mycelium using a sterile punch. One of the above mycelial blocks is inoculated on the PDA culture medium, placed in the center of the culture medium plate, sealed with sealing film, and cultured in the dark at 25-28 ℃.

3. The method for solid-state fermentation of wheat germ with Ganoderma lucidum according to claim 1, characterized in that: The method for preparing Ganoderma lucidum liquid culture in step (1) is as follows: Select activated Ganoderma lucidum culture in good growth condition, punch holes at the edge of the hyphae to obtain a 4 mm inner diameter block, pick up 5-6 blocks with an inoculation needle, and inoculate them into 100 mL of potato dextrose liquid culture medium, and culture them in the dark with shaking at 150 r / min; the culture temperature of Ganoderma lucidum liquid culture is 25-28℃, and the culture time is 7-10 days.

4. The method for solid-state fermentation of wheat germ with Ganoderma lucidum according to claim 1, characterized in that: The wheat germ solid fermentation medium in step (2) uses uncrushed wheat germ, which is separated from the bran milling material by a purifier during the wheat flour processing, and has a natural pH.

5. The method for solid-state fermentation of wheat germ with Ganoderma lucidum according to claim 1 or 4, characterized in that: The mass ratio of wheat germ to sterile water in step (2) is 1:0.7 to 1:1.

1.

6. The method for solid-state fermentation of wheat germ with Ganoderma lucidum according to claim 1, characterized in that: In step (3), 10% to 30% of the weight of wheat germ is inoculated with Ganoderma lucidum liquid culture; the fermentation temperature is 25℃ to 30℃ and the culture time is 7 to 18 days.

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