A low-salt tempeh crisp and a method for its factory production

Abstract

The application discloses a kind of low salt douchi crisp and its factory preparation method, belong to food technology field.The application is optimized by low-temperature hot air aroma preservation drying, cold energy storage instantaneous temperature difference puffing process, with douchi fine powder as core component, and the product prepared contains salt content <0.9%, taste crisp, unique flavor, rich in nutrition, accord with modern low salt, low fat health consumption trend.The specific volume of the low salt douchi crisp of the application is 2.28~2.45 mL / g, and the maximum breaking force is 11.48~12.03N;In the environment of 25 DEG C, relative humidity 65%, qualified storage period can reach 90d, and the storage stability is good.The application effectively solves the problems of traditional douchi product, such as high salt content, single taste, low processing efficiency, uneven texture of douchi crisp, poor crispness, easy loss of nutritional components and difficult factory production, and has wide market application prospect.

Description

Technical Field

[0001] This invention relates to a low-salt fermented black bean crisp and a method for its industrial preparation, belonging to the field of food technology. Background Technology

[0002] Doubanjiang (fermented black soybeans) is a traditional Chinese fermented soybean product made from soybeans through microbial fermentation. It is rich in protein, amino acids, dietary fiber, soy isoflavones, and various minerals. The fermentation process produces unique soy sauce and ester aromas, giving it a natural flavor, rich nutrition, and natural antioxidant properties, making it popular with consumers. However, with increasing health awareness, low-salt, low-fat, and high-protein foods have become mainstream. Traditional doubanjiang products suffer from high salt content, monotonous taste, crude processing methods, and difficulty in large-scale factory production, limiting their promotion and application in the snack food sector.

[0003] Currently, most fermented black bean products on the market are fermented black bean sauce or dried fermented black beans, while crispy fermented black bean products are less common. Furthermore, existing fermented black bean crispy products have several drawbacks: Firstly, some products are prepared using a deep-frying process, resulting in high oil absorption, which does not align with the trend of low-fat and healthy consumption. High-temperature frying also destroys heat-sensitive nutrients and flavor compounds in the fermented black beans, reducing their nutritional value. Secondly, the traditional processing of fermented black bean crispy products often involves improper handling. Either the drying temperature is too high, leading to flavor loss and nutrient destruction, or the particle size is uneven, resulting in a coarse texture. Insufficient mixing of raw materials also results in uneven crispy texture and poor crispness. In addition, current technology does not clearly define the impact of hot air drying parameters on the flavor compounds of fermented black beans, and it fails to fully utilize the fermentation flavor and natural antioxidant properties of fermented black beans, treating them merely as a common ingredient.

[0004] Furthermore, traditional fermented black bean products generally have a high salt content, typically above 5.0%. Long-term consumption of high-salt foods increases the risk of cardiovascular disease, which contradicts modern healthy eating principles. Simultaneously, existing fermented black bean crisps are mostly produced on a small scale by hand, resulting in low processing efficiency, inconsistent product quality, and difficulty in meeting large-scale market demands. Moreover, the synergistic effect between the added fermented black beans and the crisp's matrix remains unresolved, leading to bland flavor, a hard texture, and brittleness. Therefore, developing a low-salt, crispy, uniquely flavored fermented black bean crisp that can be mass-produced in a factory has become a pressing technical challenge in the food processing industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a low-salt fermented black bean crisp and its industrial preparation method, solving the problems of high salt content, monotonous taste, low processing efficiency, uneven texture, poor crispness, easy loss of nutrients, poor flavor retention, and difficulty in industrial production of existing fermented black bean products. It fully utilizes the characteristics of fermented black beans, such as fermentation flavor, high protein and fiber, natural antioxidants, and heat-sensitive flavor, and utilizes the influence of hot air drying on the flavor substances of fermented black beans to achieve synergistic effects between fermented black beans and crisp matrix through process optimization.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a low-salt fermented black bean crisp, which adopts the following technical solution: A low-salt fermented black bean crisp is made from the following ingredients in parts by weight: 15-25 parts of fermented black bean powder, 80-120 parts of low-gluten flour, 30-50 parts of oil, 130-170 parts of dairy products, 20-40 parts of eggs, and 50-70 parts of sugar.

[0007] Preferably, the raw material formula of the low-salt fermented black bean crisps, by weight, includes: 20 parts of fermented black bean powder, 100 parts of low-gluten flour, 40 parts of oil, 150 parts of dairy products, 30 parts of eggs, and 60 parts of sugar.

[0008] In one embodiment, the oil comprises vegetable oil.

[0009] In one embodiment, the vegetable oil includes corn oil, soybean oil, peanut oil, and palm oil.

[0010] In one embodiment, the sugar includes granulated sugar.

[0011] In one embodiment, the dairy products include whole milk, low-fat milk, and skim milk.

[0012] By adopting the above technical solution, this invention uses fermented black soybeans (douchi) as the core functional ingredient. It's not a simple addition, but rather fully utilizes the inherent characteristics of douchi to achieve multiple synergistic effects: First, the flavor peptides and free amino acids produced by the fermentation of douchi with Aspergillus oryzae can replace additional edible salt, achieving a low-salt (≤1.05%) and rich flavor, avoiding the health risks associated with long-term consumption of high-salt foods, and solving the industry pain point of bland flavor in low-salt crisps; Second, the douchi, after being dried by low-temperature hot air, pulverized, and sieved into a fine powder, can fully release the flavor substances of douchi, while simultaneously ensuring that the fine douchi powder is evenly dispersed in... In the raw material system, the texture of the crisps is avoided due to the large size of the fermented black bean particles; thirdly, the soy protein and dietary fiber in the fermented black bean, together with low-gluten flour and eggs, form a protein-starch complex gel skeleton, providing a stable supporting structure for the crisps and solving the defects of non-fried crisps being hard and brittle; fourthly, the soy isoflavones and phenolic substances in the fermented black bean provide natural antioxidants, delaying the oxidation of corn oil, eliminating the need to add synthetic antioxidants and extending the shelf life of the crisps; fifthly, the natural color of the fermented black bean gives the crisps a uniform light brownish-yellow color, eliminating the need to add artificial colorings and conforming to the trend of clean labeling. Low-gluten flour, as the main molding matrix, has good extensibility and molding properties, providing a supporting framework for the crisps and ensuring their shape stability. Corn oil, as a low-fat oil, replaces a large amount of oil in traditional frying processes, ensuring the crispy texture of the crisps while reducing the product's fat content. The addition of milk and eggs not only enriches the product's nutritional components, increasing the content of nutrients such as protein and calcium, but also improves the binding properties of the raw materials, making the mixture easier to shape. At the same time, it enhances the crisps' delicate texture and milky aroma, blending with the flavor of fermented black beans to form a unique flavor profile.

[0013] In one embodiment, the fine black bean powder is sieved through a mesh size of 80-100. The material passing through the sieve is used to prepare crisps, and the material remaining on the sieve is pulverized again and sieved once more.

[0014] By adopting the above technical solution, the mesh size of the fermented black bean powder is controlled at 80-100 mesh, which can not only ensure the full release of the fermented black bean flavor, but also ensure that the fermented black bean powder is fully mixed with other raw materials, avoiding the problem of excessively large particles causing the crisps to have a rough texture and uneven consistency. The material on the sieve is re-crushed and sieved, which improves the utilization rate of fermented black beans, reduces production costs, and ensures the uniformity of the particle size of the fermented black bean powder, laying the foundation for the formation of the protein-starch composite gel skeleton.

[0015] In one embodiment, the fermented black beans have a salt content of 1% to 5.0% and a moisture content of 35.0% to 50.0%; the low-gluten flour has a protein content of 7 to 9 g / 100 g and a moisture content of ≤14.0%; the milk is whole milk with a fat content of ≥3.2 g / 100 mL, conforming to GB 25190-2010 standard; the eggs are fresh eggs with a moisture content of ≤76.0% and a protein content of ≥12.0 g / 100 g; the raw materials may selectively contain 2 to 3 parts of β-cyclodextrin and / or 5 to 7 parts of maltodextrin to encapsulate the heat-sensitive flavor substances of the fermented black beans, further improving the flavor retention rate.

[0016] By adopting the above technical solutions, low-gluten flour with specific indicators is selected, which has a moderate protein content and can synergistically form a complex gel skeleton with fermented black bean protein and egg protein, ensuring the crispy texture of the crisps and avoiding the hard texture caused by excessive protein content. Whole milk and fresh eggs that meet national standards are selected to ensure the safety and nutritional value of the raw materials, while ensuring the stability of the raw material quality and providing a guarantee for the consistency of product quality. The addition of β-cyclodextrin can microencapsulate the heat-sensitive volatile flavor substances in fermented black beans, preventing flavor loss during subsequent hot-pressing and baking, and further improving the flavor stability of the crisps.

[0017] Secondly, the present invention provides a method for the industrialized preparation of low-salt fermented black bean crisps, employing the following technical solution: A method for the industrial production of low-salt fermented black bean crisps includes the following steps: S1. Low-temperature hot air drying of fermented black soybeans: Select low-salt fermented black soybeans, remove impurities, and place them in a hot air drying device. Dry at 50~75℃ for 4-8 hours with a hot air velocity of 1.5~2.0 m / s. Turn the black soybeans every 1.5~2 hours during the drying process to control the moisture content of the dried black soybeans to 8.0~10.0%. The optimal parameters are 55℃ for 5 hours, under which the retention rate of free amino acids is 89.7%, the retention rate of volatile flavor substances is 82.3%, and the retention rate of soy isoflavones is 91.2%. S2. Grinding and sieving: Put the dried fermented black beans from step S1 into a universal grinder. The grinding speed is 2000~3000 r / min and the grinding time is 3~5 min. After grinding, use a vibrating screen to pass through an 80~100 mesh sieve. The vibration frequency is 20~30 Hz and the sieving time is 5~10 min. Collect the material passing through the sieve as fermented black bean powder for later use. S3. Low-temperature chopping and cold storage treatment: The fermented black bean powder obtained in step S2 is put into a chopper along with low-gluten flour, corn oil, milk, eggs, white sugar and auxiliary materials. The temperature of the chopper pot is controlled at 20~25℃, the chopping speed is 500~800r / min, and the mixture is chopped and mixed for 2 minutes to obtain a uniform mixture. Then the mixture is placed in a 0~4℃ cold storage for 20~30 minutes to form a low-temperature mixture system. S4. Instantaneous temperature difference hot pressing and baking: The cold energy storage mixture from S3 is divided into portions, shaped with the aid of a pressing mold, and placed into a continuous hot pressing and baking equipment preheated to 160-190℃. The pressing gap is 1.0-1.2mm, and the baking time is 90-150s to obtain the low-salt fermented black bean crisps. The proportions, by weight, are: 15-25 parts dried fermented black bean powder, 80-120 parts low-gluten flour, 30-50 parts corn oil, 130-170 parts milk, 20-40 parts eggs, and 50-70 parts sugar. The optimal baking parameters are 180℃ and 140s. S5. Cooling and Packaging: Remove the baked crisps from the hot press and place them on a wind-cooled conveyor belt to cool to 20~25℃, controlling the moisture content of the crisps to 3.0~5.0%; then vacuum seal them in food-grade vacuum bags, and store them in an environment below 25℃ and with a relative humidity of ≤65% to obtain the finished low-salt fermented black bean crisps.

[0018] By adopting the above technical solution, this invention optimizes the entire processing flow to maximize the preservation of the flavor and nutrition of fermented black beans, taking into account the heat-sensitive flavor characteristics of fermented black beans. At the same time, it solves the problems of poor crispiness and difficulty in industrial production of non-fried crispy chips. The low-temperature hot air drying process in step S1 is achieved by controlling the drying temperature at 50~75℃, combined with specific wind speed and turning frequency. This ensures rapid drying of the fermented black beans, facilitating subsequent pulverization, while avoiding high-temperature damage to the heat-sensitive nutrients (soy isoflavones, free amino acids) and volatile flavor compounds in the fermented black beans. Compared with conventional high-temperature drying (≥100℃), the low-temperature drying of this invention can increase the retention rate of volatile flavor compounds in fermented black beans by more than 40% and the retention rate of soy isoflavones by more than 25%.

[0019] The crushing and sieving process in step S2 uses a universal crusher and a vibrating screen, with specific speed, frequency and time, to quickly crush the dried fermented black beans to the required particle size, ensuring uniform particle size of the fermented black bean powder, which lays the foundation for subsequent raw material mixing and the formation of protein-starch composite gel skeleton; the material on the screen is crushed and sieved again, which improves the utilization rate of fermented black beans and reduces production costs.

[0020] The newly added refrigeration process in step S3 involves placing the uniformly chopped mixture at 0-4℃ for energy storage. This creates a momentary temperature difference of 175-180℃ between the mixture and the subsequent 180℃ hot pressing equipment, driving the rapid vaporization of moisture in the mixture and forming a uniform and fine microporous structure. This significantly improves the crispness of the chips, solving the industry pain point of hard texture and insufficient puffing in non-fried chips. At the same time, the temperature of the chopper pot is controlled at 20-25℃ to prevent the eggs from denaturing due to excessive temperature, avoid premature oil precipitation leading to material stratification, ensure the uniformity and stability of the mixture, and prevent the heat-sensitive flavor substances of fermented black beans from volatilizing due to excessive temperature.

[0021] Step S4 involves maintaining a constant baking temperature and time, along with molding to ensure that each batch of crisps is of uniform thickness and cooked evenly. This prevents over-baking, which can lead to burnt products and nutrient loss. At the same time, it allows the protein-starch composite gel skeleton to fully form, ensuring that the crisps are crispy, not hard, and do not crumble.

[0022] The cooling and vacuum packaging step S5 can quickly reduce the temperature of the crisps, prevent them from becoming damp and soft, and at the same time isolate them from air, delay product oxidation and loss of fermented black bean flavor, and extend the product's shelf life; specific storage conditions further ensure stable product quality and meet the market circulation needs after factory production.

[0023] In one embodiment, the effects of different hot air drying temperatures on the flavor compounds of fermented black soybeans in step S1 are as follows: 55℃ for 5 hours: free amino acid retention rate 89.7%, volatile flavor compound retention rate 82.3%, and soy isoflavone retention rate 91.2%; 65℃ for 5 hours: free amino acid retention rate 81.2%, volatile flavor compound retention rate 73.5%, and soy isoflavone retention rate 84.6%; 75℃ for 5 hours: free amino acid retention rate 52.1%, volatile flavor compound retention rate 41.5%, and soy isoflavone retention rate 63.4%.

[0024] In one embodiment, the oil comprises vegetable oil.

[0025] In one embodiment, the vegetable oil includes corn oil, soybean oil, peanut oil, and palm oil.

[0026] In one embodiment, the sugar includes granulated sugar.

[0027] In one embodiment, the dairy products include whole milk, low-fat milk, and skim milk.

[0028] In one embodiment, in step S2, the pulverizing equipment is a universal pulverizer with a pulverizing speed of 2000~3000 r / min and a pulverizing time of 3~5 min; the sieving is done by a vibrating screen with a vibration frequency of 20~30 Hz and a sieving time of 5~10 min.

[0029] In one embodiment, in step S3, the temperature of the chopper's pot is controlled at 20~25℃ to prevent the eggs from denaturing due to excessive temperature, avoid premature oil precipitation leading to stratification of raw materials, and ensure the uniformity and stability of the mixed materials.

[0030] In one embodiment, in step S4, the temperature of the upper and lower heating plates of the continuous hot-press baking equipment is kept constant at 180°C, and the preheating time is 15~20 minutes; the mixed material after being divided is assisted in molding by a pressure mold to ensure that the thickness of each part of the material is uniform.

[0031] In one embodiment, in step S5, cooling to room temperature specifically means cooling to 20~25°C, and controlling the moisture content of the crisps to 3.0~5.0%; the sealed packaging adopts vacuum packaging, the packaging material is a food-grade vacuum bag, and after packaging, it is stored in an environment below 25°C and relative humidity ≤65%.

[0032] By adopting the above technical solutions, the crisps are cooled to a specific temperature, and the moisture content is controlled at 3.0-5.0%, which can prevent the crisps from becoming damp and soft, and ensure the crispy texture of the crisps. Vacuum packaging can isolate air and moisture, delay product oxidation and mold growth, and extend the product's shelf life. Food-grade vacuum bags have good barrier and sealing properties, ensuring product safety. The specific storage environment further ensures the stability of product quality and meets the needs of factory-scale distribution.

[0033] The present invention also provides the application of the method in the industrial production of fermented black bean flavored food products.

[0034] [Beneficial Effects] This invention provides a low-salt fermented black bean crisp and its industrial preparation method. Through optimized processes such as low-temperature hot air drying for aroma preservation and cold-energy storage with instantaneous temperature difference puffing, the product uses fermented black bean powder, low-gluten flour, corn oil, milk, eggs, and white sugar as main raw materials. The resulting product has a low salt content (0.82~0.85%), a crispy texture, a unique flavor, and is rich in nutrients, aligning with modern healthy consumption trends of low salt and low fat. The preparation process employs low-temperature hot air drying to preserve the flavor and nutrients of the fermented black beans, pulverizing and sieving to ensure uniform particle size of the fermented black bean powder, chopping and mixing to fully integrate the ingredients, and pressing and baking to replace traditional frying. This ensures the crispy texture of the crisps while reducing fat content. Furthermore, the entire process is simple, controllable, and suitable for large-scale industrial production. Test results show that the low-salt fermented black bean crisps prepared by this invention have a specific volume between 2.28 and 2.45 mL / g, a maximum breaking force between 11.48 and 12.03 N, and a sensory score between 80.1 and 87.5 points, which are superior to products prepared by traditional processes. In an environment of 25℃ and 65% relative humidity, the acceptable storage period can reach 90 days, demonstrating good storage stability. This invention effectively solves the problems of high salt content, monotonous taste, and low processing efficiency in traditional fermented black bean products, as well as the uneven texture, poor crispness, easy loss of nutrients, and difficulty in industrial production of fermented black bean crisps, and has broad market application prospects. 1. Maximizing the preservation of fermented black bean flavor, achieving low salt content without sacrificing aroma: This invention addresses the heat-sensitive flavor characteristics of fermented black beans by employing a low-temperature hot air drying process at 80~95℃, combined with β-cyclodextrin flavor encapsulation. This ensures that the retention rate of free amino acids in fermented black beans is ≥89.7%, and the retention rate of volatile flavor substances is ≥82.3%, completely solving the problem of flavor loss caused by high-temperature drying. At the same time, relying on the natural flavor-enhancing peptides and free amino acids produced by fermentation of fermented black beans, additional edible salt is replaced. Under the low-salt condition of ≤1.05% salt content in the finished product, the aroma of soy sauce is still rich and the taste is harmonious, overcoming the common problem of bland flavor in low-salt snack foods.

[0035] 2. Non-fried crispy forming with significantly improved texture: This invention innovatively adopts a cold energy storage treatment + instantaneous temperature difference hot pressing baking process. The temperature difference between the 0~4℃ low-temperature mixture and the 180℃ high-temperature mold drives the rapid vaporization of moisture, forming a uniform and dense microporous structure. At the same time, the soy protein and dietary fiber in the fermented black beans, together with the low-gluten flour and eggs, form a protein-starch composite gel skeleton, controlling the maximum breaking force of the crisps at 11.48~12.03N, achieving a non-fried crispy texture. This solves the defects of traditional non-fried fermented black bean crisps, such as hard texture, insufficient puffing, and easy breakage. The product breaks in the mouth, leaves no residue, and has a rich and layered taste.

[0036] 3. Enhanced Nutritional Functions for a Healthy and Leisurely Food: This invention uses fermented black soybeans as the core functional ingredient, endowing the crisps with high protein, high dietary fiber, and high levels of active ingredients. Compared to ordinary starch-based crisps, the protein content is increased by more than 15%, and the dietary fiber content is increased by more than 20%. The natural active ingredients in fermented black soybeans, such as soy isoflavones and total polyphenols, give the product natural antioxidant functions, eliminating the need for added synthetic antioxidants. At the same time, it is rich in B vitamins and minerals, meeting the needs of modern consumers for healthy, nutritious, and clean-labeled foods.

[0037] 4. Significantly improved storage stability and extended product shelf life: This invention combines vacuum sealing packaging with precise moisture control (3.0~5.0%), allowing the product to be stored for more than 90 days under qualified storage conditions of 25℃ and 65% relative humidity; at the same time, the low-temperature processing and hot-pressing shaping process avoids the product from absorbing moisture and softening, solving the industry problem of easy oxidation, easy softening, and short shelf life of fermented black bean crisps.

[0038] 5. Technological innovation adapts to industrial mass production, ensuring stable and controllable product quality: This invention upgrades traditional manual processes into continuous and standardized industrial preparation processes. Through precise control of parameters throughout the entire process, including low-temperature drying, ultra-fine grinding, low-temperature chopping, and instantaneous temperature difference hot pressing, it solves the problems of low efficiency, uneven product shape, and unstable flavor in small-scale production. The raw material utilization rate is increased to over 98%, and there is no waste from the pulverization of oversize material. The production cost is low, adaptable to large-scale industrial production, and has extremely strong industrialization value.

[0039] 6. High-value utilization of fermented black soybeans, expanding the application scenarios of traditional fermented soybean products: This invention breaks through the traditional application limitation of fermented black soybeans as only a condiment, transforming it into a core ingredient of snack chips, realizing the high-value, leisure, and convenience upgrade of traditional fermented soybean products; at the same time, it retains all the nutritional and flavor characteristics of fermented black soybeans, broadening the application boundaries of soybean deep processing and fermented foods, and providing a new path for the upgrading of the traditional soybean product industry.

[0040] 7. Green and low-carbon processing, in line with the development trend of the food industry: This invention adopts a non-fried hot pressing process, which reduces the amount of oil used by more than 60% compared with the frying process, reducing processing energy consumption and environmental pollution; the entire process is low-temperature and short-time high-temperature processing, which preserves nutrition and flavor to the greatest extent and has no harmful by-products generated, in line with the development trend of green, low-carbon and healthy modern food processing. Attached Figure Description

[0041] Figure 1 This is a flowchart of the preparation method of the low-salt fermented black bean crisps of the present invention. Detailed Implementation

[0042] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0043] Raw materials used in the examples: Low-gluten flour: food grade, protein content 7~9g / 100g, moisture content ≤14.0%, ash content ≤0.5%; Corn oil: Food grade 1, saturated fatty acid content ≤15%, peroxide value ≤0.25g / 100g, acid value ≤0.20mg / g; Whole milk: Food grade, fat content ≥3.2g / 100mL, protein content ≥2.8g / 100mL, conforming to GB25190-2010 standard; Fresh eggs: food grade, moisture content ≤76.0%, protein content ≥12.0g / 100g, conforming to GB 2749-2015 standard; White granulated sugar: Food grade 1, sucrose content ≥99.7%, loss on drying ≤0.06%; Edible salt: The main component is sodium chloride, food grade, sodium chloride content ≥99.1%, whiteness ≥85 degrees; Maltodextrin: Food grade, DE value 10~20, moisture content ≤8.0%; Fermented black bean flavoring: food grade, conforming to GB 2760-2014 standard; β-Cyclodextrin: Food grade, purity ≥98%; Fermented black beans (douchi): made from Aspergillus oryzae fermentation, with a salt content of 1%~5.0% and a moisture content of 35.0%~50.0%. Purified water: Complies with GB17323-1998 "Bottled Drinking Purified Water" standard.

[0044] Example 1: A method for preparing low-salt fermented black bean crisps This embodiment provides a low-salt fermented black bean crisp and its industrial preparation method. The specific formula and preparation method are as follows: 1. Ingredients: By weight, 20 parts of fermented black bean powder, 100 parts of low-gluten flour, 40 parts of corn oil, 150 parts of whole milk, 30 parts of fresh eggs, and 60 parts of white sugar.

[0045] 2. Preparation method: S1. Low-temperature hot air drying of fermented black beans: Select low-salt fermented black beans, remove impurities, place them in a hot air drying oven, set the drying temperature to 55℃, the hot air velocity to 1.8m / s, and dry for 6 hours. During this period, turn the fermented black beans over every 1.5 hours to control the moisture content of the dried fermented black beans to 9.0%. S2. Grinding and sieving: Put the dried fermented black beans from S1 into a universal grinder, set the grinding speed to 2500 r / min, the grinding time to 4 min, and after grinding, use a vibrating screen to pass through a 90-mesh sieve with a vibration frequency of 25 Hz and a sieving time of 8 min. Collect the material passing through the sieve as fermented black bean powder for later use. S3. Low-temperature chopping and cold storage treatment: The fermented black bean powder obtained in S2, low-gluten flour, corn oil, whole milk, fresh eggs, and white sugar are put into a chopper according to the formula. The chopper pot temperature is controlled at 22℃, the chopping speed is 650 r / min, and the chopping is mixed for 2 minutes to obtain a uniform mixture. Then the mixture is placed in a 2℃ cold storage for 25 minutes. S4. Instantaneous temperature difference hot pressing and baking: Preheat the upper and lower heating plates of the continuous hot pressing and baking equipment to 180℃ for 18 min; quickly divide the mixture obtained in S3 into portions of 18g each at room temperature, use a mold to assist in shaping, place the portioned material in the preheated hot pressing and baking equipment, quickly close the equipment for pressing and baking, with a pressing gap of 1.1 mm and a baking time of 140 s; S5. Cooling and Packaging: Remove the baked crisps from the hot-press baking equipment and place them on an air-cooled conveyor belt to cool to 22°C, controlling the moisture content of the crisps to 4.0%; then vacuum pack them using food-grade vacuum bags, and store them in an environment of 22°C and 60% relative humidity to obtain the finished low-salt fermented black bean crisps.

[0046] Example 2: Preparation of fermented black bean powder and the effect of hot air drying on the flavor compounds of fermented black beans. This embodiment investigates the effects of different hot air drying temperatures on the flavor compounds and nutritional components of fermented black beans in the preparation method S1 of low-salt fermented black bean crisps, including the following steps: Low-salt fermented black beans were selected and divided into 3 groups, 100 g in each group. They were placed in hot air drying ovens and different drying temperatures (55℃, 65℃, and 75℃) were set. The hot air velocity was 1.8 m / s for each group. The fermented black beans were dried for 5 hours. During the drying process, the fermented black beans were turned over every 1.5 hours. After drying, the moisture content, volatile flavor substance retention rate, and nutrient retention rate of each group of fermented black beans were measured.

[0047] Table 1. Effects of hot air drying on flavor compounds in fermented black soybeans

[0048] The test results show that drying at 55℃ for 5 hours is the optimal parameter. Under this condition, the moisture content of fermented black beans is suitable (9.0%), and the retention rates of free amino acids, volatile flavor substances and soy isoflavones are the highest, which can preserve the nutrition and flavor of fermented black beans to the greatest extent.

[0049] Example 3: A method for preparing low-salt fermented black bean crisps This embodiment provides a low-salt fermented black bean crisp and its industrial preparation method. Based on Example 1, maltodextrin and β-cyclodextrin are added to the raw material formula, and S3 is adjusted accordingly to optimize the product flavor, formability, and flavor retention. The specific formula and preparation method are as follows: 1. Ingredient formula: by weight, 20 parts of fermented black bean powder, 100 parts of low-gluten flour, 50 parts of corn oil, 100 parts of whole milk, 50 parts of fresh eggs, 50 parts of white sugar, 4 parts of maltodextrin, and 2.5 parts of β-cyclodextrin.

[0050] 2. The preparation method includes the following steps: S1. Drying of fermented black beans: Same as in Example 1; S2. Crushing and sieving: Same as in Example 1; S3. Low-temperature chopping and cold storage treatment: Add the fermented black bean powder obtained in S2, low-gluten flour, corn oil, whole milk, fresh eggs, and white sugar into a chopper according to the formula. Control the chopper pot temperature at 22℃ and maintain low-speed stirring (about 300 r / min). Add maltodextrin and β-cyclodextrin in sequence, then increase the chopping speed to 650 r / min and chop and mix for 2 minutes to obtain a uniform mixture. Then place the mixture in a 2℃ cold storage for 25 minutes. S4. Pressing and baking: Same as in Example 1; S5. Cooling and Packaging: Same as Example 1.

[0051] Example 4: A method for preparing low-salt fermented black bean crisps This embodiment provides a low-salt fermented black bean crisp and its industrial preparation method. Based on Example 1, fermented black bean flavoring is added to the raw material formula to enhance the product flavor, and step S3 is adjusted accordingly. The specific formula and preparation method are as follows: 1. Ingredient formula: by weight, 20 parts of fermented black bean powder, 100 parts of low-gluten flour, 50 parts of corn oil, 100 parts of whole milk, 50 parts of fresh eggs, 50 parts of white sugar, 0.2 parts of fermented black bean flavoring, and 2 parts of β-cyclodextrin.

[0052] 2. The preparation method includes the following steps: S1. Drying of fermented black beans: Select low-salt fermented black beans, remove impurities, place them in a hot air drying oven, set the drying temperature to 65℃, the hot air velocity to 2.0 m / s, and dry for 6 hours. During this period, turn the fermented black beans over every 2 hours to control the moisture content of the dried fermented black beans to 8.5%. S2. Crushing and sieving: Same as in Example 1; S3. Low-temperature chopping and cold storage treatment: Add the fermented black bean powder obtained in S2, low-gluten flour, corn oil, whole milk, fresh eggs, and white sugar into a chopper according to the formula. Control the chopper pot temperature at 22℃ and maintain low-speed stirring (about 300 r / min). Add fermented black bean flavoring and β-cyclodextrin, then increase the chopping speed to 650 r / min and chop and mix for 2 minutes to obtain a uniform mixture. Then place the mixture in a 0℃ cold storage for 30 minutes. S4. Pressing and baking: Same as in Example 1; S5. Cooling and Packaging: Same as Example 1.

[0053] Example 5: A method for preparing low-salt fermented black bean crisps This embodiment provides a low-salt fermented black bean crisp and its industrial preparation method. Based on Example 1, the hot-pressing and baking temperature in step S4 is adjusted to 170℃ and the baking time is adjusted to 150 s to optimize the crisp texture. The specific formula and preparation method are as follows: 1. Raw material formula: Same as in Example 1.

[0054] 2. The preparation method includes the following steps: S1. Drying of fermented black beans: Same as in Example 1; S2. Crushing and sieving: Same as in Example 1; S3. Low-temperature chopping and cold energy storage treatment: Same as Example 1; S4. Pressing and baking: Preheat the upper and lower heating plates of the continuous hot press baking equipment to 170℃ for 18 minutes; divide the mixture obtained in S3 into portions of 18 g each, and use a pressing mold to assist in shaping. Place the portioned material into the preheated hot press equipment, quickly close the equipment for pressing and baking, with a pressing gap of 1.1 mm and a baking time of 150 s. S5. Cooling and Packaging: Same as Example 1.

[0055] Example 6: A method for preparing low-salt fermented black bean crisps This embodiment provides a low-salt fermented black bean crisp and its industrial preparation method. Based on Example 1, the pressing gap in step S4 is adjusted to 1.2 mm and the baking time is adjusted to 140 s to optimize the fluffiness and crispness of the crisp. The specific formula and preparation method are as follows: 1. Raw material formula: Same as in Example 1.

[0056] 2. The preparation method includes the following steps: S1. Drying of fermented black beans: Same as in Example 1; S2. Crushing and sieving: Same as in Example 1; S3. Low-temperature chopping and cold energy storage treatment: Same as Example 1; S4. Pressing and baking: Preheat the upper and lower heating plates of the continuous hot press baking equipment to 180°C for 18 minutes; divide the mixture obtained in step S3 into portions, each weighing 18g, and use a pressing mold to assist in shaping. Place the portioned material into the preheated hot press equipment, quickly close the equipment, and press and bake. The pressing gap is 1.2mm, and the baking time is 140s. S5. Cooling and Packaging: Same as Example 1.

[0057] Comparative Example 1: The difference from Example 1 is that the hot air drying temperature in step S1 exceeds 75°C and is set to 90°C; the rest is the same as in Example 1.

[0058] Comparative Example 2: Compared with Example 1, the difference is that: in step S2, the fermented black beans were not sieved after being crushed, and a uniform fine powder of fermented black beans was not formed. The crushed fermented black beans were directly used for subsequent chopping and mixing. The rest is the same as in Example 1.

[0059] Comparative Example 3: Compared with Example 1, the difference is that: no cold energy storage treatment was performed in step S3, and the mixture was directly pressed and baked in step S4. The rest is the same as Example 1.

[0060] Comparative Example 4: Compared with Example 1, the difference is that the baking temperature in step S4 is set to 160°C instead of 180°C, the baking time is extended to 160 seconds, and a continuous hot-press baking device is not used; instead, an electric griddle is used. All other aspects are the same as in Example 1.

[0061] Comparative Example 5: Compared with Example 1, the difference is that the traditional frying process is used instead of the pressing and baking process of S4. The mixture obtained in S3 is divided into portions, pressed into shape, and fried in corn oil at 180°C for 140 seconds. The mixture is then removed and drained of oil. The rest is the same as in Example 1.

[0062] Comparative Example 6: Compared with Example 1, the difference is that fermented black beans are omitted from the raw material formula, while the rest are the same as in Example 1.

[0063] Comparative Example 7: Compared with Example 1, the difference is that S1 is omitted, and the fermented black beans are directly crushed and sieved to prepare fermented black bean crisps. All other aspects are the same as in Example 1.

[0064] Comparative Example 8: The difference from Example 1 is that the fermented black bean powder is not added in S3, but is instead sprinkled on the surface of the baked crisps; otherwise, it is the same as in Example 1.

[0065] Comparative Example 9: Compared with Example 1, the difference is that the amount of fermented black bean powder added is adjusted to 10 parts, 30 parts, and 50 parts in the raw material formula, which is equivalent to controlling the mass ratio of fermented black bean powder to low-gluten flour to be 1:10, 2:10, and 1:2, respectively. All other aspects are the same as in Example 1.

[0066] Comparative Example 10: Compared with Example 1, the difference is that the cold energy storage treatment time in S3 is adjusted to 15 min, 40 min, and 60 min, while the rest are the same as in Example 1.

[0067] Comparative Example 11: The difference from Example 1 is that the fermented black beans are pulverized through 60 mesh and 120 mesh to prepare fermented black bean crisps; otherwise, they are the same as in Example 1.

[0068] Test Example 1: Physical Characterization and Sensory Quality Evaluation 1. Experimental Methods: The products obtained in Examples 1 and 3-6 were compared with the products obtained in Comparative Examples 1-8. The specific methods are as follows: (1) The specific volume was determined by the millet displacement method: weigh the sample mass m, immerse it in a graduated cylinder containing a known volume of millet, record the volume change V, and calculate the specific volume (mL / g) = V / m. Each group of samples was measured in parallel 5 times and the average value was taken.

[0069] (2) The textural properties were determined by puncture test using a TA.XTPlus texture analyzer: A P / 2 probe (2mm diameter cylindrical) was selected, and the pre-test speed was set to 2.0mm / s, the test speed to 1.0mm / s, and the post-test speed to 10.0mm / s. The trigger force was 5g, and the downward pressure distance was 5mm. The maximum breaking force (N) and the work done by the probe during the breaking process were recorded. The smaller the maximum breaking force, the more brittle the brittle sheet.

[0070] (3) Determination of salt content: The salt content of the samples was determined by the national standard GB 5009.44-2016. Each group of samples was measured in parallel 5 times and the average value was taken.

[0071] (4) A sensory evaluation team of 10 people was formed to score and evaluate the samples from four dimensions: color (20 points), shape (20 points), crispness (30 points), and flavor (30 points). The color is best when it is golden and uniform without scorch marks; the shape is best when the surface is flat and the thickness is uniform; the crispness is best when it crumbles in the mouth without leaving any residue; and the flavor is best when it has a rich black bean flavor, no off-flavors, and a harmonious taste.

[0072] (5) Determination of volatile flavor compounds: Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) was used for determination. 2.0 g of the pulverized sample was weighed and placed in a 20 mL headspace vial, sealed, and equilibrated in a 60 °C water bath for 30 min. A 50 / 30 μm DVB / CAR / PDMS extraction head was inserted into the headspace vial, and extraction was performed at 60 °C for 40 min. The sample was then analyzed at 250 °C for 5 min via the GC-MS injection port. A DB-WAX capillary column (30 m × 0.25 mm × 0.25 μm) was used as the chromatographic column, and high-purity helium was used as the carrier gas (flow rate 1.0 mL / min). The temperature program was as follows: 40℃ for 3 min → increased to 120℃ at 5℃ / min → increased to 230℃ at 8℃ / min and held for 10 min; the ion source was an electron impact ionization source (EI) with an electron energy of 70 eV and a mass scan range of m / z 35~450; qualitative analysis was performed using the NIST17 standard mass spectrometry library combined with the retention index, and quantitative analysis was performed using the peak area normalization method. The relative content and retention rate of characteristic volatile flavor substances of fermented black soybeans were calculated, and each sample was measured in triplicate and the average value was taken.

[0073] 2. Experimental Data: Table 2. Physical properties and sensory evaluation data of low-salt fermented black bean crisps for each group

[0074] 3. Test Result Analysis: The experimental data above show that the low-salt fermented black bean crisps prepared in Examples 1 and 3-6 of this invention have significantly better performance indicators than those in Comparative Examples 1-8, fully verifying the effectiveness of the process optimization and synergistic effect of the raw materials in this invention. The specific interpretation is as follows: (1) Physical property analysis: The specific volume of Examples 1 and 3-6 is between 2.28 and 2.45 mL / g, which is significantly higher than that of the comparative examples (1.98 to 2.18 mL / g). This indicates that the cold energy storage + instantaneous temperature difference hot pressing baking process adopted in this invention can make the mixture form a uniform and fine microporous structure, effectively improving the fluffiness of the crisps. The maximum breaking force is controlled within the range of 11.48 N to 12.03 N. Although the value of Comparative Example 5 is similar to that of the Examples, Comparative Example 5 is prepared by frying. The oil immersion leads to a decrease in the specific volume of the crisps and a greasy taste. The oil content of the finished product is much higher than that of the Examples of this invention, which does not meet the product positioning of healthy light food. The maximum breaking force of the other comparative examples all exceed 13 N. The crisps are too hard and not crispy enough. This indicates that the protein-starch composite gel skeleton formed by the black bean powder, low-gluten flour and eggs in this invention effectively solves the defects of hard texture and poor crispness of non-fried crisps. Example 3, with its optimized formability due to the addition of β-cyclodextrin, exhibited the lowest maximum breaking force (11.48 N) and the best crispness. Example 6, with its adjusted pressing gap of 1.2 mm, achieved the highest specific volume (2.45 mL / g) and the best fluffiness. Comparative Example 6, lacking fermented black beans, could not form a composite gel framework, resulting in a loose and brittle texture. Comparative Example 7, with its undried and directly pulverized fermented black beans, suffered from uneven material viscosity, leading to a hardened crisp texture. Comparative Example 8, with fermented black beans applied after baking, could not participate in framework construction, resulting in poor textural stability. The physical properties of the aforementioned comparative examples were all inferior to those of the examples.

[0075] (2) Salt content analysis: The salt content of all examples was controlled between 0.82% and 0.85%, ≤1.05%, which meets the requirements for low-salt products. Comparative Example 6 did not add fermented black beans and could not rely on fermented flavor substances to replace salt. The salt content came only from trace backgrounds of raw materials such as flour, milk, and eggs, with a salt content of only 0.08%, far lower than that of the examples. This fully demonstrates that the flavor peptides and free amino acids produced by fermented black beans can effectively replace additional edible salt, achieving the effect of low-salt flavor enhancement and solving the industry pain point of bland flavor in low-salt crisps. The small difference in salt content among the examples indicates that the raw material ratio and process parameters of this invention are stable and the product quality is consistent.

[0076] (3) Analysis of the retention rate of volatile flavor substances: The retention rates of characteristic volatile flavor substances of fermented black beans in Examples 1, 3, 5 and 6 are all ≥80%. Among them, Example 3 has the highest retention rate (88.7%) due to the addition of β-cyclodextrin to encapsulate heat-sensitive flavor substances. The retention rate of Example 4 is reduced to 73.5% due to drying at 65℃, but it is still significantly higher than Comparative Example 1 (40.8%) and Comparative Example 7 (43.5%). This proves that the low temperature hot air drying process of 50~75℃ in this invention can effectively retain the flavor substances of fermented black beans. In contrast, Comparative Example 1 has a large loss of heat-sensitive flavor substances due to high temperature drying at 90℃. Comparative Example 5 used a deep-frying process, but the high-temperature oil bath caused the loss of flavor substances, with a retention rate of only 57.5%. Comparative Example 8 was coated with fermented black beans after baking, but the flavor substances could not be integrated into the crispy chip system, with a retention rate of only 35.6%. The flavor retention rate was much lower than that of Example 1, which had the fermented black bean powder mixed in during the chopping stage in advance. This shows that integrating the pre-treated fermented black bean powder into the raw material system and baking it together is more conducive to the stable retention of flavor substances and can give the product a richer and more harmonious fermented black bean flavor. Comparative Example 6 did not add fermented black beans and had no characteristic flavor substances of fermented black beans, with a retention rate of 0%.

[0077] (4) Sensory evaluation analysis: The sensory scores of Examples 1 and 3-6 were all above 80 points, with Example 3 having the highest score (87.5 points), characterized by a uniform light brownish-yellow color, regular shape, easy to crumble in the mouth, and a harmonious and rich aroma of fermented black beans and milk. Example 4 suffered a slight loss of flavor due to the increased drying temperature, resulting in a score of 80.1 points. The scores of all comparative examples were below 77 points, with Comparative Example 3 having the lowest sensory score (65.9 points) due to poor crispness caused by the lack of cold storage treatment. Comparative Example 2 had uneven particle size due to the fermented black beans not being sieved. Comparative Example 1 had a rough texture and a score of only 68.5; Comparative Example 2 had a greasy texture due to the frying process and significant loss of flavor, scoring 76.8; Comparative Example 3 lacked the aroma and flavor of fermented black beans and had a simple, bland flavor with excessive sweetness and a lack of umami, scoring 70.5; Comparative Example 4 had no drying pretreatment, resulting in poor fermented black bean flavor and a rough texture, scoring 66.3; Comparative Example 5 had fermented black beans added after baking, resulting in a dispersed flavor and poor harmony, scoring 72.1. These findings fully demonstrate that the process optimization and synergistic effect of the raw materials in this invention can significantly improve the sensory quality of the crisps.

[0078] Test Example 2: Comparison Experiment of Key Process and Formulation Parameters 1. Experimental Methods To verify the necessity of the formulation and process steps of this invention and the optimization of parameters, single-factor comparative experiments were set up for whether or not fermented black beans were added and how they were added, the pretreatment method of fermented black beans, the amount of fermented black beans added, the cold storage time, and the particle size of the powder. The measured indicators included specific volume, maximum breaking force, retention rate of characteristic volatile flavor substances of fermented black beans, sensory score, and yield of formed products. Each group was measured in parallel three times and the average value was taken. The experimental groups corresponded to Example 1 and Comparative Examples 6 to 11.

[0079] (1) Determination of total free amino acids: Each group of crispy samples was crushed and mixed, and 2.00 g of sample was accurately weighed and placed in a 100 mL beaker. 6 mL of 5% sulfosalicylic acid was added, and the mixture was ultrasonically extracted for 0.5 h. The protein was then extracted by standing at 4℃ for 1 h. The pH was then adjusted to about 2.2, and the mixture was allowed to stand to allow the fermented soybean powder to settle. 2 mL of the supernatant was transferred to a 2 mL PE centrifuge tube and centrifuged at 10000 r / min for 15 min. 1 mL of the supernatant was passed through a 0.22 μm microporous membrane, and the filtrate was kept for later use.

[0080] Amino acid analysis was performed using an automated amino acid analyzer. Analytical conditions: Column: Hitachi 855-4507 (60 mm × 4.6 mm, 3 μm); Column temperature: 135 ℃; Gradient elution with lithium citrate (PBF) buffer; Detection wavelength: 570 nm + 440 nm; Flow rate: elution pump 0.35 mL / min, derivatization pump 0.30 mL / min; Analysis time: 148 min.

[0081] A standard curve was established using a mixed amino acid standard, and quantification was performed using the external standard method. The contents of each free amino acid component were summed to obtain the total free amino acid content (unit: mg / 100g sample). Each sample was measured in triplicate, and the arithmetic mean was taken.

[0082] (2) Determination of free amino acid retention rate: After determining the total amount of free amino acids, using fresh, low-salt fermented soybeans that have not been dried by hot air as the reference sample, the total amount of free amino acids in fermented soybeans treated under different hot air drying conditions was determined. The formula for calculating the free amino acid retention rate is: Free amino acid retention rate (%) = Total amount of free amino acids in dried fermented soybeans ÷ Total amount of free amino acids in fresh, undried fermented soybeans × 100. Each group of samples was measured in parallel three times, and the arithmetic mean was taken.

[0083] 2. Experimental Data Table 3. The effect of whether or not fermented black beans are added and the method of addition on the quality of the crisps.

[0084] Table 4. Effects of low-temperature drying pretreatment of fermented black soybeans on the quality of crispy chips.

[0085] Table 5. Effect of fermented black bean addition amount on the quality of crispy chips

[0086] Table 6. Effects of cold storage time on the texture and sensory properties of crisp flakes.

[0087] Table 7. Effect of fermented black bean powder mesh size on the quality of crispy chips

[0088] 3. Results Analysis 3.1 As shown in Table 3, the textural properties, flavor retention, sensory score, and crude protein content of Example 1 are significantly better than those of Comparative Examples 6 and 8. Comparative Example 6 did not add fermented black beans, thus lacking characteristic flavor compounds and failing to form a protein-starch complex gel framework, resulting in a loose texture and extremely bland flavor. Comparative Example 8 used a method of coating fermented black beans after baking, which prevented the flavor compounds from integrating into the crispy chip system, with only a small amount adsorbed on the surface. This significantly reduced the retention rate of characteristic flavors and prevented the chips from participating in gel framework construction, leading to poor textural stability. This demonstrates that fermented black beans must be mixed with the raw materials before baking, which is a necessary condition for forming excellent crispy texture and unique flavor. The total amount of free amino acids in Example 1 is much higher than in the other two groups. Comparative Example 6 lacks umami substances from fermentation, and the fermented black beans in Comparative Example 8 only adhere to the surface and cannot be fully dissolved to participate in flavor balance. This further verifies that mixing fermented black beans in advance is a necessary condition for achieving low salt content without reducing aroma and enhancing flavor levels.

[0089] 3.2 As shown in Table 4, in Example 1, after being dried at a low temperature of 55℃, the retention rates of free amino acids and soy isoflavones in the fermented black beans reached over 89%, resulting in crispy chips with lower maximum breaking force, better crispness, and better sensory quality. In contrast, Comparative Example 7 was directly pulverized without low-temperature drying, leading to uneven pulverization due to the excessive moisture content of the fermented black beans. This resulted in clumping during material mixing, significant loss of nutrients and flavor substances, and hard, coarse-tasting crispy chips. This demonstrates that low-temperature hot air drying is a necessary pretreatment process for fermented black beans, effectively preserving their nutritional and flavor-active substances.

[0090] 3.3 As shown in Table 5, when the amount of fermented black bean powder added is 20 parts, the specific volume, crispness, sensory score and molding yield of the crisps are all optimal. If the amount added is too low, the flavor is insufficient. If the amount added is too high, the ratio of fermented black bean protein to dietary fiber is too large, resulting in excessive viscosity of the mixture, hard texture of the crisps and a significant decrease in molding rate. This proves that the present invention limits the amount of fermented black bean powder to 20 parts as the optimal amount, which can balance the flavor, texture and processing characteristics.

[0091] 3.4 As shown in Table 6, when the cold storage time is 25 min, the specific volume of the crispy chips is the largest, the micropores are uniform and fine, and the crispness score is the highest. If the cold storage time is too short (15 min), the temperature difference between the mixture and the hot pressing equipment is insufficient, resulting in poor puffing effect and a hard texture. If the cold storage time is too long (40 min and above), the material temperature is too low, leading to abnormal moisture state, collapse of microporous structure, and decrease in crispness. This proves that the present invention limits the cold storage time to 20~30 min to achieve the best instantaneous temperature difference puffing effect.

[0092] 3.5 As can be seen from Table 7, when the pulverization mesh number of fermented soybeans is 90 mesh (in the range of 80 - 100 mesh), the chips have a delicate and residue-free taste and the highest forming yield rate; when the mesh number is too low (60 mesh), the particles are coarse, the taste is rough, and the forming stability is poor; when the mesh number is too high (120 mesh), the powder is too fine, the material is prone to adhesion, and the crispness decreases. This proves that the present invention defines 80 - 100 mesh as the optimal pulverization mesh number of fermented soybeans, which can balance the taste, flavor release and processing adaptability.

[0093] Test Example 3: Storage Stability Test 1. Experimental method: Select the low-salt fermented soybean chips (with the highest sensory score) prepared in Example 3, divide them into 3 groups, with 100 g in each group, and store them in an environment of 25°C, 30°C, and 35°C respectively, with a relative humidity of 65%. Regularly take samples to detect the moisture content, acid value and sensory quality of the chips, record the changes during the storage period, and measure each group of samples 3 times in parallel and take the average value. Storage stability evaluation criteria: moisture content ≤ 5.0%, acid value ≤ 0.50 mg / g, and sensory score ≥ 75 points are qualified, and mildew and peculiar smell are unqualified.

[0094] 2. Experimental data: Table 8 Storage stability data of low-salt fermented soybean chips under different storage conditions

[0095] 4. Analysis of storage stability: From the experimental data in Table 8, it can be seen that the storage stability of the low-salt fermented soybean chips prepared by the present invention is closely related to the storage temperature: under the conditions of 25°C and a relative humidity of 65%, the storage period can reach 90 d. At this time, the moisture content of the chips is 4.9%, the acid value is 0.42 mg / g, and the sensory score is 76.2 points, all of which meet the qualified standards; when stored for 120 d, the moisture content and acid value exceed the qualified range, and the sensory score is lower than 75 points, which is judged as unqualified. Under the conditions of 30°C and a relative humidity of 65%, the qualified storage period of the chips is 30 d, and it is unqualified when stored for 60 d; under the conditions of 35°C and a relative humidity of 65%, the qualified storage period of the chips is only within 30 d, and it is unqualified when stored for 30 d.

[0096] To sum up, the low-salt fermented soybean chips prepared by the present invention have good stability when stored in an environment of below 25°C and a relative humidity ≤ 65%, and can meet the market circulation and storage requirements after industrial production, further proving the rationality and practicality of the preparation process of the present invention.

[0097] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A method for preparing low-salt fermented black bean crisps, characterized in that, Includes the following steps: S1. Low-temperature aroma preservation and drying of fermented black beans: Select low-salt fermented black beans, remove impurities, and dry with hot air at a low temperature of 50~75℃, controlling the moisture content to 8.0%~10.0%; S2. Grinding and sieving: Grind and sieve the dried fermented black beans from S1 to obtain fine fermented black bean powder; S3. Low-temperature chopping and cold energy storage treatment: Chop and mix the fermented black bean powder described in S2 with low-gluten flour, oil, dairy products, egg liquid and sugar according to the formula; The mixture was then refrigerated at 0-5℃ for 20-30 minutes. S4, Instantaneous temperature difference hot pressing and baking: The mixture after S3 cold storage and energy storage is divided into portions, molded, pressed and baked; S5. Cooling and Packaging: Remove the baked and shaped crisps, cool them, and control the moisture content of the crisps to ≤5.0%; The salt content of the low-salt fermented black beans is ≤3.0%; The raw material formula of the low-salt fermented black bean crisps, by weight, includes: 15-25 parts of fermented black bean powder, 80-120 parts of low-gluten flour, 30-50 parts of oil, 130-170 parts of dairy products, 20-40 parts of eggs, and 50-70 parts of sugar.

2. The preparation method according to claim 1, characterized in that, The raw material formula of the low-salt fermented black bean crisps, by weight, includes: 20 parts of fermented black bean powder, 100 parts of low-gluten flour, 40 parts of oil, 150 parts of whole milk, 30 parts of eggs, and 60 parts of sugar.

3. The preparation method according to claim 1, characterized in that, In step S1, the hot air velocity of the low-temperature hot air drying is 1.5~2.0 m / s, the drying time is 4~8 h, and the fermented black beans are turned over once every 1.5~2 h.

4. The preparation method according to claim 1, characterized in that, In step S2, the sample is passed through an 80-100 mesh sieve.

5. The preparation method according to claim 1, characterized in that, In step S3, add 2-3 parts of cyclodextrin and 5-7 parts of maltodextrin.

6. The preparation method according to claim 1, characterized in that, In step S4, the pressing and baking temperature is 160~190℃, the pressing gap is 1.0~1.5 mm, and the baking time is 90~150 s.

7. The preparation method according to claim 1, characterized in that, In step S5, the cooling temperature is 20~25℃.

8. The preparation method according to claim 1, characterized in that, The oils include vegetable oils; Optionally, the vegetable oil includes corn oil, soybean oil, peanut oil, and palm oil.

9. Low-salt fermented black bean crisps prepared by any one of the preparation methods according to claims 1 to 8.

10. The application of the preparation method according to any one of claims 1 to 8 in the industrial production of fermented black bean flavored food.

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