Solid-state fermented oat as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of food processing, and particularly relates to solid-state fermented oat as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, taking raw oats, cleaning, soaking, cooking, and cooling to obtain cooked oats; s2, adding a saccharifying agent, aroma-producing yeast and compound enzyme into the cooked oats for first-stage fermentation culture, and then adding lactobacillus plantarum for second-stage fermentation culture to obtain fermented oats; and S3, drying the obtained fermented oats to obtain a finished product, and sealing and storing the finished product. Through the processes of oat selection, soaking, cooking, cooling, inoculation, fermentation, drying and the like, the flavor and taste of the oats are improved, and the nutritional value of the oats is improved. According to the process and the formula, protein, essential amino acid, non-essential amino acid, beta-glucan, total acid, reducing sugar and the like of the oats are increased to different extents compared with those before fermentation, and the nutritional value is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing, and in particular relates to solid-state fermented oats and a preparation method and application thereof. Background Art

[0002] Oats are produced in huge quantities worldwide, but most of them are used in the feed industry, and only about 12% are used in the food field. Its processing and utilization in the food field is also relatively superficial. Common products include oat flakes, oat flour, oat rice, etc., which only undergo primary physical processing such as flaking or grinding, and the product form is single.

[0003] Currently, there are few products that use oats processed by fermentation, and the few products that use grain fermentation have obvious bitterness, such as red yeast rice. There is even less research on reducing bitterness during oat fermentation.

[0004] For example, patent CN202410924614.2 discloses a red yeast rice oat and a preparation method thereof, which adopts a solid-state fermentation process and uses oats instead of rice to make red yeast rice oat; however, red yeast rice is traditionally used as a medicine and can only be used as a colorant in food, and is not in the form of ordinary food. In addition, red yeast rice has a very obvious bitter taste, and the invention does not mention the effect of the fermentation process on improving the bitterness. Patent CN202311026124.2 discloses a pure oat-based fermented beverage and a preparation method thereof, which uses pure oat beverage as a fermentation raw material and adds Lactococcus lactis for fermentation, thereby increasing the β-glucan content in the oat beverage and improving the taste of the oat beverage; this invention is a liquid fermentation process, and is a single strain fermentation, which is different from the solid-state fermentation process adopted by the present invention, and the difference is quite large. Patent CN202110338164.5 provides a method for preparing oat fermentation extract, which uses oats as a fermentation substrate, inoculates bifidobacteria and yeast for fermentation, and obtains oat fermentation extract rich in multiple active ingredients; this invention is a liquid fermentation process, and the fermentation product obtained is used in the field of cosmetics preparation, does not involve the food field, and there is no relevant research on bitterness.

[0005] Therefore, it is very necessary to provide a solid-state fermented oat, which is of great significance for improving the flavor and taste of oat. Summary of the Invention

[0006] The purpose of the present invention is to provide a solid-state fermented oatmeal and a preparation method and application thereof, so as to improve the flavor and taste of the oatmeal and increase its nutritional value.

[0007] To this end, the present invention provides the following technical solutions.

[0008] A first aspect of the present invention provides a method for preparing solid-state fermented oats, the method comprising the following steps: S1: Washing and soaking raw oats, steaming, and cooling to obtain cooked oats; S2: adding a saccharifying agent, aroma yeast, and complex enzyme to cooked oats for a first-stage fermentation culture, and then adding Lactobacillus plantarum for a second-stage fermentation culture to obtain fermented oats; S3: Drying the fermented oats to obtain a finished product, which is then sealed and stored.

[0009] In a preferred embodiment of the present invention, in step S1, the cleaning process is: using tap water to rinse, soak and remove impurities, and then draining the water for later use.

[0010] In a preferred embodiment of the present invention, in step S1, the soaking process is: soaking the washed oats in water.

[0011] In a preferred embodiment of the present invention, the oats are mixed with water in a mass-to-volume ratio of 1 g:1.5 mL to 1 g:2.0 mL.

[0012] In a preferred embodiment of the present invention, the soaking time is 1-2 hours.

[0013] In a preferred embodiment of the present invention, in step S1, the cooking conditions are: temperature: 100° C., time: 35-60 min.

[0014] In a preferred embodiment of the present invention, in step S2, the saccharifying agent is Rhizopus, and the amount of Rhizopus added is 0.5-1.0% of the mass of the oats; or The saccharifying agents are mesophilic α-amylase and glucoamylase, the addition amount of the mesophilic α-amylase is 0.1-0.2% of the mass of the oats, and the addition amount of the glucoamylase is 0.1-0.2% of the mass of the oats.

[0015] In a preferred embodiment of the present invention, in step S2, the amount of the aroma yeast added is 0.5-1.0% of the mass of the oats.

[0016] In a preferred embodiment of the present invention, in step S2, the composition and content of the complex enzyme are as follows, calculated by mass percentage of oats: acid protease 0.03-0.1%, flavor protease 0.3-1.5%, aminopeptidase 0.3-1.5%, and phytase 0-0.1%.

[0017] In a preferred embodiment of the present invention, in step S2, the fermentation conditions of the first stage are: temperature: 30-35°C, time: 24-48h.

[0018] In a preferred embodiment of the present invention, in step S2, the amount of Lactobacillus plantarum added is 0.1-0.8% of the mass of the oats.

[0019] In a preferred embodiment of the present invention, in step S2, the fermentation conditions of the second stage are: temperature: 30-35°C, time: 12-24h.

[0020] In a preferred embodiment of the present invention, in step S3, the drying process is: first, using microwaves to dry the fermented oats to a moisture content of about 25%, and then using 100°C hot air drying for 1.5 hours to reduce the moisture content to below 12%.

[0021] A second aspect of the present invention provides a use of solid-state fermented oats prepared according to the preparation method as described above in the preparation of oat products.

[0022] In a preferred embodiment of the present invention, the oat products include instant oatmeal, oat powder, oat crisps, oat noodles, and oat drinks.

[0023] By means of the above technical solution, the present invention has at least the following advantages: The present invention provides a solid-state fermentation preparation process for oats. Through oat selection, soaking, steaming, cooling, inoculation, fermentation, and drying, the process enhances the flavor and taste of the oats and increases their nutritional value. This process and formulation improve the oats' protein, essential amino acids, non-essential amino acids, β-glucan, total acid, and reducing sugar content compared to pre-fermentation levels, enhancing their nutritional value. (1) Compared to conventional oat flakes (unfermented), the fermented oats possess a rich, sweet aroma with appropriate sourness and sweetness. (2) Compared to fermented oats not treated with a complex enzyme preparation, the formulation significantly reduces the intense bitterness produced during fermentation. (3) Compared to conventional oat flakes (unfermented), the fermented oats' protein, essential amino acid, and non-essential amino acid contents increase by 10.07%, 6.64%, and 7.76% (when converted to a 0% moisture content, the same applies below). Protein and amino acids are essential substances for human life and contribute to tissue formation and growth. ④ Compared with regular unfermented oatmeal, the total acid content increased by 1002.17% after fermentation, and the reducing sugar content increased from 0 to 20.36 g / 100g. These two substances add a suitable sour and sweet flavor to the oats. ⑤ Compared with regular unfermented oatmeal, the β-glucan content increased by 11.42%. β-glucan is a soluble dietary fiber and an important functional substance in oats. It can serve as a carbon source for probiotics, selectively stimulating their growth and activity and promoting their reproduction. It can also be metabolized to produce short-chain fatty acids, which can lower intestinal pH and repair damaged colonic epithelial cells.

[0024] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0026] The strains and enzymes involved in the following examples include: Rhizopus: Angel Rhizopus Q303, purchased from Angel Yeast Co., Ltd.

[0027] Aroma yeast: Angel Aroma Active Dry Yeast, purchased from Angel Yeast Co., Ltd.

[0028] Lactobacillus plantarum: Lactobacillus plantarum Lactobacillus plantarum , strain number WSH048, was deposited in the General Microbiology Center of China Culture Collection Administration on August 20, 2021, with the deposit number: CGMCC No.23159.

[0029] Acidic protease: 100,000 U / g enzyme activity (solid), purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd.

[0030] Flavor protease: 50,000 U / g enzyme activity (solid), purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd.

[0031] Aminopeptidase: 5000 U / g enzyme activity (solid), purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd.

[0032] Phytase: 100,000 U / g enzyme activity (solid), purchased from Cangzhou Xiasheng Enzyme Biotechnology Co., Ltd.

[0033] Example 1: A method for preparing solid-state fermented oats, comprising the following steps: ① Cleaning: Weigh 1000 g of oats, rinse and soak them in tap water to remove dust and other impurities on the surface of the oat grains, and filter out floating objects such as rice husks. Then drain the water and set aside.

[0034] ② Soak: Place the cleaned oats in a clean container, add 1600 mL of water, and soak for 1.5 hours.

[0035] ③Steaming: Drain the soaked oats, transfer them to a steamer, and steam at 100℃ for 35 minutes.

[0036] ④ Cooling: Cool the cooked oats naturally to below 30°C, weigh and calculate the amount of water required to adjust the total mass of the system to 1500 g (i.e., 50% water content based on the dry weight of the oats).

[0037] ⑤ Inoculation: Transfer the oats to a clean fermentation container. Weigh 10 g of Rhizopus, 10 g of aroma yeast, 0.5 g of acid protease, 10 g of flavor protease, 1 g of aminopeptidase, and 0.5 g of phytase. Dissolve them partially in water in a beaker and transfer to the oats, adding the remaining water. Stir thoroughly to evenly combine the strains, enzyme preparation, and oats. Complete the inoculation.

[0038] ⑥ Fermentation: After inoculation, seal the fermentation container with a porous lid and cover with six layers of gauze. This ensures gas exchange between the inside and outside of the fermentation container, providing oxygen for microbial growth while preventing foreign matter from falling and bacterial contamination. After fermentation at 32°C for 24 hours, inoculate the oats with 5.0 mL of Lactobacillus plantarum culture. Stir thoroughly to evenly mix the culture and oats, and continue fermenting at 32°C for another 24 hours to obtain fermented oats.

[0039] ⑦ Drying: First, use microwaves to quickly dry the fermented oats to reduce the moisture content of the oats to about 25%. Then use 100°C hot air drying for 1.5 hours to reduce the moisture content of the oats to below 12%. The finished product is obtained and sealed for storage.

[0040] Example 2: A method for preparing solid-state fermented oats, comprising the following steps: ① Cleaning: Weigh 1000 g of oats, rinse and soak them in tap water to remove dust and other impurities on the surface of the oat grains, and filter out floating objects such as rice husks. Then drain the water and set aside.

[0041] ② Soak: Place the cleaned oats in a clean container, add 1600 mL of water, and soak for 1.5 hours.

[0042] ③Steaming: Drain the soaked oats, transfer them to a steamer, and steam at 100℃ for 35 minutes.

[0043] ④ Cooling: Cool the cooked oats naturally to below 30°C, weigh and calculate the amount of water required to adjust the total mass of the system to 1500 g (i.e., 50% water content based on the dry weight of the oats).

[0044] ⑤ Inoculation: Transfer the oats to a clean fermentation container. Weigh 10 g of aroma yeast, 1 g of mesophilic α-amylase, 2 g of glucoamylase, 5 g of flavor protease, and 0.5 g of phytase. Dissolve them partially in water in a beaker and transfer to the oats, adding the remaining water. Stir thoroughly to evenly combine the strains, enzyme preparation, and oats. This completes the inoculation.

[0045] ⑥ Fermentation: After inoculation, seal the fermentation container with a porous lid and cover with six layers of gauze. This ensures gas exchange between the inside and outside of the fermentation container, providing oxygen for microbial growth while preventing foreign matter from falling and bacterial contamination. Fermentation is then continued at 32°C. At the 28th hour of fermentation, inoculate the oats with 4.0 mL of Lactobacillus plantarum culture. Stir thoroughly to evenly mix the culture and oats, and continue fermenting at 32°C for 20 hours to obtain the fermented oats.

[0046] ⑦ Drying: First use microwave to quickly dry the fermented oats to reduce the moisture content of the oats to about 25%, then use 100℃ hot air drying for 1.5 hours to reduce the moisture content of the oats to below 12%.

[0047] Example 3: The only difference between this comparative example and Example 1 is that: in the inoculation process of step ⑤, 0.1 g of acid protease, 1 g of flavor protease, and 1 g of aminopeptidase (i.e., 0.01%, 0.1%, and 0.1%, respectively) were weighed and inoculated into oats, and the rest remained the same as in Example 1.

[0048] Comparative Example 1: The only difference between this comparative example and Example 1 is that no complex enzyme preparation was added during the inoculation process in step ⑤, that is, only 10 g of Rhizopus and 10 g of aroma yeast were weighed and inoculated into the oats, and the rest was consistent with Example 1.

[0049] Comparative Example 2: This comparative example differs from Example 1 in that during the fermentation process in step ⑥, a lid without holes was used to completely seal the fermentation container to isolate the air, and the rest was consistent with Example 1.

[0050] Comparative Example 3: The only difference between this comparative example and Example 1 is that the inoculation of step ⑤ and the fermentation process of step ⑥ were not performed, and the rest were consistent with Example 1.

[0051] Experiment 1: Sensory evaluation of different fermented oats The fermented oats of Examples 1-3 and Comparative Examples 1-2 were subjected to sensory evaluation. The specific steps included selecting 15 trained professionals to conduct sensory evaluations and scoring the four aspects of smell, sourness, sweetness, and bitterness. The scoring was based on a 100-point scale, with each aspect receiving 25 points. The specific scoring criteria are shown in Table 1 below.

[0052] Table 1 Scoring criteria

[0053] The following scoring table was obtained by averaging the scores of all the evaluators. The unfermented comparative example 3 was used as a reference for scoring, and its smell, sourness, sweetness, bitterness, etc. were all scored as 0. The results are shown in Table 2 below: Table 2 Scoring results of oats in each group

[0054] As shown in Table 1, the fermented oats obtained in Examples 1 and 2, which employed the formulation and process required by the present invention, achieved significantly higher sensory scores than those of Comparative Examples 1-2. The odor score of the fermented oats in Example 2 was slightly lower than that of Example 1. However, in practical applications, the formulation can be flexibly adjusted to meet the desired scenario to obtain the desired fermented oats for different purposes. In Example 3, the amounts of acid protease, flavor protease, and aminopeptidase used were below the lower limit of the range, and the odor, sourness, and sweetness scores were not significantly different from those of Examples 1 and 2. However, the bitterness was significantly stronger, resulting in a lower score.

[0055] Comparative Example 1 did not strictly follow the required formula, that is, one or more enzyme preparations such as acid protease, flavor protease, aminopeptidase, and phytase were not used to treat the oats. The odor, sourness, and sweetness scores of the resulting fermented oats were similar to those of Examples 1 and 2, but the bitterness was significantly stronger, which was disliked by most evaluators. Comparative Example 2 did not strictly follow the required process, that is, the fermentation container was completely sealed during the fermentation period. The fermentation degree of the resulting fermented oats was extremely low, with insufficient fermentation flavor, and almost no sourness or sweetness. Since the bitterness was mainly produced during the fermentation period, the bitterness was also extremely weak, resulting in a high bitterness score.

[0056] Experiment 2: Component detection of different fermented oats Since Comparative Example 3 is completely unfermented oats, while Examples 1 and 2 are fermented in strict accordance with the method of the present invention to produce oats with better flavor, this experiment only compares the ingredients of Examples 1, 2, and Comparative Example 3 to demonstrate the advantages of fermentation. Comparative Examples 1 and 2 scored low in the sensory evaluation and were not suitable for food products. Therefore, they were eliminated from subsequent experiments and no further index measurements were performed.

[0057] The relevant components of oats are measured by the following method: Protein detection method: refer to GB 5009.5-2016 method 1.

[0058] Dietary fiber testing method: refer to GB 5009.88-2023.

[0059] Reducing sugar detection method: refer to GB 5009.7-2016 Method 1.

[0060] Carbohydrate detection method: refer to GB 28050-2011.

[0061] Total acid detection method: refer to GB 12456-2021 method 1.

[0062] Determination method of essential and non-essential amino acids: refer to GB 5009.124-2016.

[0063] β-glucan detection method: refer to NY / T 2006-2011.

[0064] The specific test results are shown in Table 3 below: Table 3 Component detection of each group of fermented oats

[0065] Note: All indicators are converted to dry weight (i.e. when the water content is 0%).

[0066] As can be seen from Table 3, compared with Comparative Example 3, the protein content in the fermented oats of Example 1 increased by 10.07%, the essential amino acids increased by 6.64%, and the non-essential amino acids increased by 7.76%. The protein content in the fermented oats of Example 2 decreased by 7.78%, the essential amino acids decreased by 14.17%, and the non-essential amino acids decreased by 1.25%. Based on the fact that protein is a nutrient necessary for maintaining normal growth and metabolism of the human body, the increase in amino acid and protein content helps to enhance the nutrition of oats. It can be seen that within the scope of the formula provided by the present invention, the flexible adjustment of protein content can be achieved by using strains and enzyme preparations in different proportions. Compared with Comparative Example 3, the β-glucan content in the fermented oats of Example 1 increased by 11.42%, and the β-glucan content in the fermented oats of Example 2 increased by 272.03%. β-glucan is a natural polysaccharide present in oats, which has multiple biological activities such as promoting the proliferation of intestinal probiotics. The increase in its content also helps to enhance the nutritional value of oats. Compared with Comparative Example 3, the total acid in the fermented oats of Example 1 increased by 1002.17%, and the total acid in the fermented oats of Example 2 increased by 476.60%. In the unfermented comparative example 3, no reducing sugar was detected before fermentation. After fermentation, the content of Example 1 was 20.36 g / 100 g, and that of Example 2 was 8.72 g / 1000 g. These two substances provide sourness and sweetness to oats, and both are derived from the growth and metabolism of microorganisms, rather than exogenous additions, and can achieve a clean label for the product. Within the scope of the formula provided by the present invention, the use of bacterial strains and enzyme preparations in different proportions can achieve flexible adjustment of the total acid and reducing sugar content.

[0067] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make slight changes or modifications to equivalent embodiments of the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, 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 solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing solid-state fermented oats, characterized in that: The method comprises the following steps: S1: Washing and soaking raw oats, steaming, and cooling to obtain cooked oats; S2: adding a saccharifying agent, aroma yeast, and complex enzyme to cooked oats for a first-stage fermentation culture, and then adding Lactobacillus plantarum for a second-stage fermentation culture to obtain fermented oats; S3: Drying the fermented oats to obtain a finished product, which is then sealed and stored.

2. The preparation method according to claim 1, characterized in that In step S1, the cleaning process is: using tap water to rinse, soak and remove impurities, and then draining the water for later use; The soaking process is as follows: soaking the cleaned oats in water; The oats and water are mixed in a mass volume ratio of 1 g:1.5 mL to 1 g:2.0 mL; The soaking time is: 1-2h; The steaming conditions are: temperature: 100° C., time: 35-60 min.

3. The preparation method according to claim 1, characterized in that In step S2, the saccharifying agent is Rhizopus, and the amount of Rhizopus added is 0.5-1.0% of the mass of the oats; or The saccharifying agents are mesophilic α-amylase and glucoamylase. The addition amount of the mesophilic α-amylase is 0.1-0.2% of the mass of the oats, and the addition amount of the glucoamylase is 0.1-0.2% of the mass of the oats.

4. The preparation method according to claim 1, characterized in that In step S2, the amount of the aroma yeast added is 0.5-1.0% of the mass of the oats; Calculated by mass percentage of oats, the components and contents of the complex enzyme are: 0.03-0.1% of acid protease, 0.3-1.5% of flavor protease, 0.3-1.5% of aminopeptidase, and 0-0.1% of phytase.

5. The preparation method according to claim 1, characterized in that In step S2, the first stage fermentation conditions are: temperature: 30-35°C, time: 24-48h.

6. The preparation method according to claim 1, characterized in that In step S2, the amount of Lactobacillus plantarum added is 0.1-0.8% of the mass of the oats.

7. The preparation method according to claim 1, characterized in that In step S2, the second stage fermentation conditions are: temperature: 30-35°C, time: 12-24h.

8. The preparation method according to claim 1, characterized in that In step S3, the drying process is as follows: first, the fermented oats are dried using microwaves to a moisture content of about 25%, and then hot air is dried at 100° C. for 1.5 hours to reduce the moisture content to below 12%.

9. Use of the solid-state fermented oats prepared by the preparation method according to any one of claims 1 to 8 in the preparation of oat products.

10. The use according to claim 9, characterized in that The oat products include instant oatmeal, oat powder, oat crisps, oat noodles, and oat drinks.

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