Processing method of non-fried raw peanuts

Abstract

The application discloses a processing method of non-fried raw melon seeds, and belongs to the technical field of nut roasted food. The method comprises the following steps: raw material screening, cleaning, 70%-77% edible alcohol spraying disinfection, pure water washing, dehydration, tunnel quick freezing at-30 DEG C to-45 DEG C, three-stage vacuum freeze-drying process treatment, and finally sealing and packaging. The application is processed by low-temperature non-frying, does not need to add any food additive, can avoid oil oxidation and rancidity from the root, significantly prolongs the product shelf life, forms a uniform honeycomb structure in the melon seeds, has better crispness than traditional roasted products, meanwhile, retains the raw material nutrients and biological germination activity, has a low glycemic index, is suitable for people who want to lose weight and diabetic patients, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of snack food processing technology, specifically relating to a method for processing raw sunflower seeds without roasting. Background Technology

[0002] Sunflower seeds are a widely produced and popular type of roasted nut in my country. They are rich in unsaturated fatty acids, plant protein, vitamin E, and various minerals, offering both nutritional and nutritional value as a snack. Currently, commercially available sunflower seed products mainly use heat processing techniques such as roasting, boiling, and baking, which give the products a crispy texture and flavor through high-temperature treatment.

[0003] Chinese patent application CN104824732A discloses a method for processing sunflower seeds, employing a segmented high-temperature roasting process under vacuum. The sunflower seeds are soaked in broth and then roasted under vacuum at 160-180°C, with phased temperature adjustments to achieve puffing and flavor infusion. Chinese patent application CN107822067A discloses another method for processing sunflower seeds, using a combination of ingredient cooking, flavored broth soaking, steaming, and drying to prepare seasoned sunflower seeds.

[0004] The aforementioned existing technologies all have the following drawbacks: First, high-temperature heat processing easily causes the unsaturated fatty acids in sunflower seeds to oxidize and become rancid, leading to a rapid increase in acid value and peroxide value. This results in a short shelf life at room temperature, only about one month in summer and about three months in winter, with significant losses during storage and distribution. Second, to achieve flavor and a crispy texture, various food additives such as salt, flavorings, sweeteners, and antioxidants need to be added during the process, which does not conform to the trend of natural and healthy consumption and poses a risk of excessive additives. Third, prolonged high-temperature processing will destroy the heat-sensitive vitamins and active plant components in sunflower seeds, completely eliminating the biological germination activity of the raw materials. Fourth, the pore structure formed by traditional roasting or baking processes is limited, leaving room for improvement in the crispness of the product. Furthermore, high-temperature roasting can easily cause discomfort such as internal heat after consumption.

[0005] Therefore, developing a non-roasted, additive-free sunflower seed processing method that preserves the nutritional activity of raw materials, has a long shelf life, and produces crispy seeds is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a non-roasted, pure raw sunflower seeds processing method, which solves the problems of existing high-temperature roasting processes for sunflower seeds, which easily lead to oil oxidation and rancidity, short shelf life, and damage to the nutritional components and biological germination activity of raw materials, as well as the addition of various food additives in existing processes.

[0007] The objective of this invention can be achieved through the following technical solutions: A method for processing unroasted, raw sunflower seeds includes the following steps: (1) Raw material screening: Select plump sunflower seeds without mold, and remove impurities and shriveled seeds; (2) Washing: Wash with tap water to obtain cleaned sunflower seeds; (3) Surface disinfection: Spray the cleaned sunflower seeds with 70%~77% edible alcohol by volume for 1~5 minutes; (4) Rinsing and dehydration: Use sterile pure water to spray and rinse the surface of the sunflower seeds to remove residual alcohol, and then use compressed air to blow away the free water on the surface of the sunflower seeds; (5) Tunnel quick-freezing: The sunflower seeds are sent into the tunnel quick-freezing device and quick-frozen for 3 to 10 minutes at an environment of -30℃ to -45℃; (6) Vacuum freeze drying: The quick-frozen sunflower seeds are placed in trays and sent into a vacuum freeze drying equipment, and the drying is completed in sequence through the pre-freezing stage, the sublimation drying stage, and the desorption drying stage; (7) Packaging and storage: After drying, the sunflower seeds are sealed and packaged in a clean environment and stored in the warehouse.

[0008] Addressing the core shortcomings of existing high-temperature roasting processes, a comprehensive low-temperature physical processing route was constructed. First, raw material screening removes shriveled, broken, and impurity seeds, ensuring uniformity and basic quality. Tap water spraying initially washes away dust, impurities, and microorganisms from the seed surface. To address the need for microbial control on the seed surface, conventional high-temperature sterilization is abandoned in favor of edible alcohol spraying. This method rapidly kills pathogenic microorganisms such as bacteria and mold at room temperature without denaturing the seed protein or inactivating active substances, a fundamental prerequisite for preserving biological activity. After sterilization, sterile purified water spraying thoroughly removes any residual alcohol, preventing any impact on product flavor and safety. Compressed air is then used to blow away surface free moisture, preventing the surface moisture from sublimating and forming a hard shell during the initial freeze-drying stage, thus ensuring a uniform internal pore structure. Based on this, a tunneling process is introduced... The freezing process allows the sunflower seeds to quickly pass through the maximum ice crystal formation zone in a short time. This causes the internal moisture to form small, evenly distributed ice crystals, significantly reducing mechanical damage to the cell walls caused by ice crystals. This provides a structural basis for preserving cell integrity and biological activity. Finally, a three-stage vacuum freeze-drying process is used. The pre-freezing stage stabilizes the ice crystal structure, the sublimation drying stage removes most of the free water, and the desorption drying stage removes deep-bound water. The entire process is completed in a low-temperature, high-vacuum, low-oxygen environment. This avoids oil oxidation and nutrient decomposition caused by high temperatures and allows the sublimation of ice crystals to build a uniform honeycomb porous structure inside the sunflower seeds, achieving high crispness without additives. Finally, the seeds are sealed and packaged in a clean environment to prevent the intrusion of external oxygen and microorganisms, ensuring the long-term storage stability of the product.

[0009] Furthermore, in step (3), the volume fraction of the edible alcohol is 75%, and the spraying disinfection time is 2-3 minutes. 75% volume fraction of edible alcohol is the optimal concentration for sterilizing food surfaces. This combination of parameters can achieve a qualified sterilization effect in the shortest time, while minimizing alcohol residue, thus balancing sterilization efficiency and product flavor.

[0010] Furthermore, in step (4), the pure water spraying pressure is 0.2~0.4MPa, and the rinsing time is 30~60s; the compressed air pressure is 0.3~0.5MPa, and the purging time is 20~40s. This parameter range ensures thorough alcohol rinsing without causing grain damage due to excessive water pressure. Compressed air purging can efficiently remove surface water, improving subsequent freeze-drying efficiency and pore uniformity.

[0011] Furthermore, in step (5), the tunnel quick-freezing temperature is -35℃ to -40℃, and the quick-freezing time is 5 to 8 minutes. This temperature range and duration can ensure that the sunflower seeds quickly pass through the maximum ice crystal formation zone, minimizing the ice crystal size, while also taking into account the energy consumption and efficiency of industrial production.

[0012] Furthermore, in step (6), the temperature of the plate during the pre-freezing stage is -35℃ to -45℃, the cooling rate is 0.5 to 1.5℃ / min, and the temperature is maintained until the center temperature of the melon seeds reaches the preset freezing temperature. This cooling rate range can balance the ice crystal size and cell wall integrity. If the rate is too fast, it will easily cause cell wall stress rupture; if it is too slow, the ice crystals will grow too large and damage the cell structure. This range can achieve the optimal balance between the two.

[0013] Furthermore, the cooling rate during the pre-freezing stage is 0.8~1.2℃ / min, and the final core temperature of the sunflower seeds is -40℃~-42℃.

[0014] Furthermore, in step (6), the system vacuum degree of the sublimation drying stage is 10~30 Pa, the plate temperature is 20℃~35℃, and the drying time is 8~18h. This vacuum degree and plate temperature matching can ensure the continuous sublimation of solid ice crystals, while the material temperature is always below the eutectic point, avoiding the melting and collapse of ice crystals and ensuring the smooth formation of honeycomb pore structure.

[0015] Furthermore, the vacuum degree of the sublimation drying stage is 15~25 Pa, the plate temperature is 25℃~30℃, and the drying time is 10~15 h.

[0016] Furthermore, in step (6), the system vacuum degree of the analytical drying stage is 3~10 Pa, the plate temperature is 25℃~45℃, and the drying time is 4~8 h. A higher vacuum degree combined with appropriate heating can effectively remove the bound water inside the material, control the final moisture content within a safe threshold, and improve the long-term storage stability of the product.

[0017] Furthermore, the vacuum degree of the analytical drying stage is 5~8 Pa, the plate temperature is 30℃~40℃, and the drying time is 5~7 h.

[0018] The beneficial effects of this invention are: The raw material screening process ensures that the seeds are plump and uniform. Washing with tap water initially removes dust, impurities, and microorganisms from the surface, laying the foundation for the final product quality. Sterilization at room temperature for 1-5 minutes using 70%-77% edible alcohol effectively kills surface microorganisms while completely avoiding the damage to nutrients and biological activity caused by heat sterilization. Rinsing with purified water and blowing away surface moisture with compressed air eliminates alcohol residue and prevents surface free water from interfering with the freeze-drying process, ensuring a uniform internal pore structure. A tunnel-freezing process rapidly freezes the material at -30℃ to -45℃ for 3-10 minutes, forming fine, uniform ice crystals. This minimizes mechanical damage to the cell walls and preserves the product's nutritional value. Cellular structural integrity is ensured through a three-stage vacuum freeze-drying process involving pre-freezing, sublimation drying, and desorption drying. This process removes internal moisture from the sunflower seeds through solid-state sublimation, maintaining a low-temperature, low-oxygen environment throughout. This avoids the oxidation and rancidity of oils caused by high-temperature roasting, significantly extending the product's shelf life. Furthermore, the sublimation of moisture creates a uniform honeycomb-like porous structure within the seeds, achieving a crispier texture superior to traditionally roasted products without the need for added crisping agents. The low-temperature environment also preserves heat-sensitive nutrients and bioactivity such as unsaturated fatty acids and vitamins, maintaining the product's germination ability and resulting in a low glycemic index, making it suitable for specific populations. Finally, the seeds are sealed and packaged in a clean environment, isolating them from external contaminants and oxygen, further enhancing the product's hygiene, safety, and storage stability. Moreover, this invention uses only sunflower seeds as the sole raw material, without any food additives throughout the entire process. The product is purely natural and guilt-free, avoiding the additive problems associated with traditional flavored sunflower seeds, truly achieving zero additives. Furthermore, the absence of high-temperature roasting makes it less likely to cause internal heat after consumption. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0020] Example 1 The processing method for unroasted, raw sunflower seeds in this embodiment includes the following steps: (1) Raw material screening: Select 10kg of sunflower seeds with full grains and no mold, and remove impurities, shriveled grains and broken grains by wind selection and vibrating sieve. (2) Washing: Use tap water to spray and wash the seeds to remove dust, impurities and microorganisms from the surface of the seeds, and obtain cleaned seeds; (3) Surface disinfection: The cleaned sunflower seeds are spread evenly on the conveyor belt, and the surface is sprayed evenly with 75% edible alcohol by volume. The conveying speed is controlled so that the disinfection treatment time is 2.5 min. (4) Rinsing and dehydration: Rinse with food-grade pure water at 0.3MPa pressure for 45s to thoroughly wash away residual alcohol on the surface; then blow with clean compressed air at 0.4MPa for 30s to remove free moisture from the surface of the sunflower seeds. (5) Tunnel quick-freezing: Spread the sunflower seeds evenly on the tray and put them into the tunnel quick-freezing machine. Quick-freeze them for 6 minutes at -38℃. (6) Vacuum freeze drying: The quick-frozen sunflower seeds are placed in trays and sent into a vacuum freeze drying equipment for drying in three stages: ① Pre-freezing stage: The temperature of the plate is set to -40℃, and the temperature is reduced at a rate of 1.0℃ / min. The temperature is maintained until the center temperature of the sunflower seeds reaches -40℃. ② Sublimation drying stage: The system vacuum degree is controlled at 20Pa, the plate temperature is raised to 28℃, and drying is maintained for 12h; ③ Drying stage: The vacuum level is increased to 6 Pa, the plate temperature is raised to 35℃, and drying is maintained for 6 hours; (7) Packaging and warehousing: After drying, the material is slowly depressurized and discharged. It is then packaged in a Class 10,000 cleanroom using aluminum-plastic composite film, sealed, and stored at room temperature.

[0021] Example 2 The processing method for unroasted, raw sunflower seeds in this embodiment includes the following steps: (1)~(2): Same as Example 1; (3) Surface disinfection: Spray the surface of the melon seeds evenly with 70% edible alcohol by volume, and disinfect for 5 minutes; (4) Rinsing and dehydration: Rinse with pure water at 0.2 MPa pressure for 60 seconds to remove residual alcohol; then blow with clean compressed air at 0.3 MPa for 40 seconds. (5) Tunnel quick-freezing: The tunnel is sent into a tunnel quick-freezing machine and quick-frozen at -30℃ for 10 minutes; (6) Vacuum freeze drying: ① Pre-freezing stage: The plate temperature is -35℃, and the temperature is reduced at a rate of 0.5℃ / min, and then kept warm until the center temperature is -35℃; ② Sublimation drying stage: vacuum degree 30Pa, plate temperature 20℃, drying for 18h; ③ Drying stage: Vacuum degree 10Pa, plate temperature 25℃, drying for 8h; (7) Packaging and warehousing: Same as in Example 1.

[0022] Example 3 The processing method for unroasted, raw sunflower seeds in this embodiment includes the following steps: (1)~(2): Same as Example 1; (3) Surface disinfection: Spray the surface of the melon seeds evenly with 77% edible alcohol by volume, and disinfect for 1 minute; (4) Rinsing and dehydration: Rinse with pure water at 0.4 MPa pressure for 30 seconds to remove residual alcohol; then blow with clean compressed air at 0.5 MPa for 20 seconds. (5) Tunnel quick-freezing: The tunnel is sent into a tunnel quick-freezing machine and quick-frozen for 3 minutes at -45℃. (6) Vacuum freeze drying: ① Pre-freezing stage: The plate temperature is -45℃, and the temperature is reduced at a rate of 1.5℃ / min, and then kept warm until the center temperature is -45℃; ② Sublimation drying stage: vacuum degree 10Pa, plate temperature 35℃, drying for 8h; ③ Drying stage: Vacuum degree 3Pa, plate temperature 45℃, drying for 4h; (7) Packaging and warehousing: Same as in Example 1.

[0023] Example 4 The processing method for unroasted, raw sunflower seeds in this embodiment includes the following steps: (1)~(2): Same as Example 1; (3) Surface disinfection: Spray the surface of the melon seeds evenly with 72% edible alcohol by volume, and disinfect for 3 minutes; (4) Rinsing and dehydration: Rinse with pure water at 0.25 MPa pressure for 50 seconds to remove residual alcohol; then blow with clean compressed air at 0.35 MPa for 35 seconds. (5) Tunnel quick-freezing: The tunnel is sent into a tunnel quick-freezing machine and quick-frozen at -35℃ for 8 minutes; (6) Vacuum freeze drying: ① Pre-freezing stage: The plate temperature is -38℃, and the temperature is reduced at a rate of 0.8℃ / min until the center temperature is -38℃; ② Sublimation drying stage: vacuum degree 25Pa, plate temperature 25℃, drying for 15h; ③ Drying stage: Vacuum degree 8Pa, plate temperature 30℃, drying for 7h; (7) Packaging and warehousing: Same as in Example 1.

[0024] Example 5 The processing method for unroasted, raw sunflower seeds in this embodiment includes the following steps: (1)~(2): Same as Example 1; (3) Surface disinfection: Spray the surface of the melon seeds evenly with 76% edible alcohol by volume, and disinfect for 1.5 minutes; (4) Rinsing and dehydration: Rinse with pure water at 0.35 MPa pressure for 35 seconds to remove residual alcohol; then blow with clean compressed air at 0.45 MPa for 25 seconds. (5) Tunnel quick-freezing: The tunnel is sent into a tunnel quick-freezing machine and quick-frozen at -42℃ for 4 minutes; (6) Vacuum freeze drying: ① Pre-freezing stage: The plate temperature is -42℃, and the temperature is reduced at a rate of 1.2℃ / min, and then kept warm until the center temperature is -42℃; ② Sublimation drying stage: vacuum degree 15Pa, plate temperature 32℃, drying for 10h; ③ Drying stage: Vacuum degree 4Pa, plate temperature 40℃, drying for 5h; (7) Packaging and warehousing: Same as in Example 1.

[0025] Example 6 The processing method for unroasted, raw sunflower seeds in this embodiment includes the following steps: (1)~(6) are the same as in Example 1; (7) Packaging and warehousing: After drying, the material is depressurized and discharged. It is vacuum-sealed in a Class 10,000 cleanroom using composite PET / alumina PET / CPP plastic bags and stored at room temperature.

[0026] Comparative Example 1: Traditional Five-Spice Roasted Melon Seeds Using a commercially available standard five-spice stir-frying process, the steps are as follows: (1) Raw material screening: 10kg of sunflower seeds from the same batch were selected and impurities were removed by winnowing; (2) Cooking to infuse flavor: Prepare the seasoning liquid. For every 10kg of melon seeds, add 200g of salt, 50g of licorice, 20g of star anise, 20g of cinnamon, 20g of cloves, and 15g of Sichuan pepper. Add 30L of water and bring to a boil. Then add the melon seeds and simmer over low heat for 1 hour, stirring twice during the process. (3) Draining and airing: Take out the cooked melon seeds, drain off the surface soup, and air them at room temperature for 2 hours until there are no obvious water stains on the surface; (4) Roasting: Put the sunflower seeds into the drum roaster and roast them at an initial temperature of 180℃ for 15 minutes. Then, reduce the temperature to 120℃ and roast for 10 minutes until the moisture content of the sunflower seeds reaches the standard. (5) Cooling and packaging: After being removed from the pot, the product is cooled to room temperature for 30 minutes and then sealed in ordinary polyethylene plastic bags.

[0027] Comparative Example 2: Vacuum-roasted sunflower seeds The preparation was carried out according to the process of Example 1 in Publication No. CN104824732A, and the steps are as follows: (1) Raw material screening: Select 10kg of sunflower seeds from the same batch, screen to remove impurities, put them into 5% salt water and stir for 10 minutes, then rinse them with clean water. (2) Soup preparation: Weigh 500g of licorice, 200g of salt, 3g of saccharin, 100g of star anise, 200g of cinnamon, 200g of cloves and 100g of Sichuan pepper, add 20L of water and simmer for 3 hours to obtain soup liquid; (3) Soaking and frying: Soak the melon seeds in the soup for 1 hour, with a mass ratio of melon seeds to soup of 1:2; then vacuum the water and heat it to 160°C under vacuum for frying. When the mass of the soup is reduced to 15% of the original mass, cool it down to 140°C and fry for 1 hour, then cool it down to 100°C and fry for 2 hours. (4) Discharge and packaging: Depressurize and remove the sunflower seeds, sieve them and cool them at room temperature, then seal them in ordinary polyethylene plastic bags.

[0028] Comparative Example 3: Conventional freeze-dried sunflower seeds The conventional freeze-drying process, which employs no tunnel-free quick-freezing and no three-stage precise temperature control, involves the following steps: (1) Raw material screening: Select 10kg of sunflower seeds from the same batch and screen to remove impurities; (2) Cleaning: Rinse the surface of the sunflower seeds with tap water to remove dust, then drain at room temperature for 30 minutes; (3) Static pre-freezing: Place the sunflower seeds directly into the freeze-drying equipment and let them stand at -20℃ for 12 hours for pre-freezing without controlled cooling. (4) One-time freeze drying: vacuum up to 30 Pa, plate temperature constant at 40 °C, freeze dry continuously for 20 h, without distinguishing between sublimation and desorption stages; (5) Packaging: After freeze drying, the material is discharged directly and packaged with the same aluminum-plastic composite film as in Example 1.

[0029] Performance testing 1. Moisture content: Refer to the direct drying method in GB5009.3-2016 "National Food Safety Standard - Determination of Moisture in Food". Weigh the sunflower seed kernel sample and dry it in an oven at 105℃ until constant weight. Calculate the moisture content based on the mass difference before and after drying.

[0030] 2. Acid value: Tested according to the method described in Method II of GB5009.229-2016; 3. Peroxide value: Referring to the titration method in GB5009.227-2016 "National Food Safety Standard for Determination of Peroxide Value in Food", the crushed sunflower seed kernel sample was weighed, and the oil was extracted by shaking with petroleum ether. The solvent was recovered by rotary evaporation to obtain crude oil. The oil was dissolved in a mixture of chloroform and glacial acetic acid, and a saturated potassium iodide solution was added to react in the dark. After adding water, the solution was titrated with sodium thiosulfate standard solution until the blue color disappeared. The content of active oxygen in each 100g sample was calculated.

[0031] 4. Crispness: A three-point fracture test was conducted using a texture analyzer. Uniformly sized sunflower seeds were placed flat on two parallel support columns with a span of 10 mm. The probe was pressed downwards at a speed of 1 mm / s, and the peak force at the point of breakage was recorded in N. The smaller the value, the better the crispness. Twenty parallel samples were tested in each group, and the average value was taken.

[0032] 5. Germination rate: 100 whole and plump sunflower seeds were randomly selected and evenly placed in a petri dish lined with two layers of moist filter paper. The seeds were then placed in a constant temperature incubator at 25℃ and cultured in the dark for 72 hours. Germination was defined as the radicle breaking through the seed coat by more than 2 mm. The percentage of normally germinated seeds was counted.

[0033] 6. Microbiological testing: The total bacterial count shall be tested in accordance with GB4789.2-2022 "National Food Safety Standard for Microbiological Examination of Food - Determination of Total Colony Count", GB4789.3-2025 "National Food Safety Standard for Microbiological Examination of Food - Coliform Count", and GB4789.15-2016 "National Food Safety Standard for Microbiological Examination of Food - Mold and Yeast Count".

[0034] The results are shown in Table 1: Table 1

[0035] As shown in Table 1, in terms of oxidative stability, the acid value of the examples remained stable at 0.79~0.88 mg / g, and the peroxide value was generally at an extremely low level, with most batches only at 0.04~0.07 g / 100g, far lower than that of Comparative Example 1 (conventional roasting, 0.13 g / 100g) and Comparative Example 2 (vacuum roasting, 0.11 g / 100g). The core reason is that the present invention operates in a low-temperature, high-vacuum, and low-oxygen environment throughout the process, inhibiting the oxidation of oil free radicals and hydrolytic rancidity at the source of the reaction; while high-temperature roasting accelerates the thermal oxidation of unsaturated fatty acids, and even with a vacuum environment, the oxidative promoting effect of high temperature cannot be offset. Compared with Comparative Example 3 (conventional freeze-drying, 0.08 g / 100g), the present invention reduces cell damage and oil exposure through tunnel freezing, and with the precise temperature and pressure control of three-stage freeze-drying, the oxidation control effect is better, which can significantly extend the product shelf life.

[0036] In terms of crispness, the breaking force of the example was only 11.8~13.5N, and the crispness was significantly better than the two heat-processed comparative examples. Traditional frying relies on high-temperature evaporation and dehydration, which easily causes the material structure to shrink and harden, usually requiring the addition of crisping agents to improve the texture; although vacuum frying has a certain puffing effect, the protein denaturation caused by high temperature still limits the improvement of crispness. This invention forms small ice crystals through rapid freezing, and after sublimation drying, leaves uniform and dense honeycomb-like pores inside, achieving a superior crisp texture without any additives. Compared with the ordinary freeze-drying comparative example (16.9N), the large ice crystals formed by slow pre-freezing lead to uneven pore size and local structural collapse, resulting in a weaker crispness and texture than this invention.

[0037] Regarding moisture content, the moisture content in the examples was stably controlled at 2.1%~2.8%, all below the safe threshold of 3%, and the moisture distribution inside the grains was uniform. The moisture values ​​of the heat-processed comparative examples appeared similar, but in reality, they exhibited a gradient distribution of dry exterior and moist interior. After surface hardening, they were prone to absorbing moisture and softening, resulting in poor storage stability. Comparative Example 3, with its ordinary freeze-dried moisture content as high as 3.5%, failed to effectively remove deep-bound water due to the lack of a dedicated desorption drying stage. Excessive moisture content accelerates microbial growth and oil hydrolysis during storage.

[0038] Regarding germination rate and microbiological indicators, the germination rate of the examples reached 89%~93%, fully preserving the biological activity of sunflower seeds and overcoming the technical limitation that heat processing inevitably leads to inactivation. The germination rate of the two heat-processed comparative examples was 0%, and that of the ordinary freeze-dried comparative example was only 20%. The large ice crystals formed by slow pre-freezing severely damaged the embryo cell structure, leading to a large number of inactivated seeds. At the microbiological level, the total bacterial count of all examples was <10 CFU / g, with negative coliform bacteria and no detected mold, indicating a hygiene level far higher than that of the comparative examples. Although the heat-processed products underwent high-temperature sterilization, secondary contamination was prone to occur during the cooling, seasoning, and packaging processes. Ordinary freeze-dried products do not have a dedicated sterilization process, resulting in a higher initial microbial load.

[0039] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for processing raw, unroasted sunflower seeds, characterized in that, Includes the following steps: (1) Raw material screening: Select plump sunflower seeds without mold, and remove impurities and shriveled seeds; (2) Washing: Wash with tap water to obtain cleaned sunflower seeds; (3) Surface disinfection: Spray the cleaned sunflower seeds with 70%~77% edible alcohol by volume for 1~5 minutes; (4) Rinsing and dehydration: Use sterile pure water to spray and rinse the surface of the sunflower seeds to remove residual alcohol, and then use compressed air to blow away the free water on the surface of the sunflower seeds; (5) Tunnel quick-freezing: The sunflower seeds are sent into the tunnel quick-freezing device and quick-frozen for 3 to 10 minutes at an environment of -30℃ to -45℃; (6) Vacuum freeze drying: The quick-frozen sunflower seeds are placed in trays and sent into a vacuum freeze drying equipment, and the drying is completed in sequence through the pre-freezing stage, the sublimation drying stage, and the desorption drying stage; (7) Packaging and storage: After drying, the sunflower seeds are sealed and packaged in a clean environment and stored in the warehouse.

2. The processing method for unroasted raw sunflower seeds according to claim 1, characterized in that, The volume fraction of the edible alcohol mentioned in step (3) is 75%, and the spraying time is 1~4 minutes.

3. The processing method for unroasted raw sunflower seeds according to claim 1, characterized in that, In step (4), the pure water spray pressure is 0.2~0.4MPa and the rinsing time is 30~60s; the compressed air pressure is 0.3~0.5MPa and the purging time is 20~40s.

4. The processing method for unroasted raw sunflower seeds according to claim 1, characterized in that, In step (5), the tunnel quick-freezing temperature is -35℃ to -40℃, and the quick-freezing time is 5 to 8 minutes.

5. The processing method for unroasted raw sunflower seeds according to claim 1, characterized in that, In step (6), the temperature of the plate layer during the pre-freezing stage is -35℃ to -45℃, the cooling rate is 0.5 to 1.5℃ / min, and the temperature is maintained until the center temperature of the melon seeds reaches the preset freezing temperature.

6. The processing method for unroasted raw sunflower seeds according to claim 5, characterized in that, The cooling rate during the pre-freezing stage is 0.8~1.2℃ / min, and the final core temperature of the sunflower seeds is -40℃~-42℃.

7. The processing method for unroasted raw sunflower seeds according to claim 1, characterized in that, The system vacuum degree of the sublimation drying stage in step (6) is 10~30Pa, the plate temperature is 20℃~35℃, and the drying time is 8~18h.

8. The processing method for unroasted raw sunflower seeds according to claim 7, characterized in that, The sublimation drying stage has a vacuum degree of 15~25 Pa, a plate temperature of 25℃~30℃, and a drying time of 10~15 h.

9. The processing method for unroasted raw sunflower seeds according to claim 1, characterized in that, In step (6), the system vacuum degree of the analytical drying stage is 3~10 Pa, the plate temperature is 25℃~45℃, and the drying time is 4~8h.

10. The processing method for unroasted raw sunflower seeds according to claim 9, characterized in that, The vacuum degree during the analytical drying stage is 5~8 Pa, the plate temperature is 30℃~40℃, and the drying time is 5~7 h.

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