Selenium-rich peanut protein powder and production process thereof

Abstract

The invention relates to selenium-enriched peanut protein powder and a production process thereof, and belongs to the technical field of food processing. The process comprises the following steps: a, screening and pretreating raw materials; b, crushing at low temperature; c, performing ultrahigh-pressure auxiliary degreasing; d, desolventizing the cake meal; e, performing ultrasonic-enzymolysis synergistic deodorization; f, gradient mild alkaline extraction; g, precise acid precipitation; h, washing and freeze-drying; i, superfine grinding; and j, nitrogen-filled packaging. According to the production process of the selenium-rich peanut protein powder, the four core technologies of low-temperature control and protection, ultrahigh-pressure auxiliary degreasing, ultrasonic-enzymolysis synergistic deodorization and gradient mild alkali extraction have a synergistic effect; the core problems that in a traditional production process, due to high-temperature processing, the organic selenium loss rate is high, protein denaturation is serious, due to incomplete fishy smell removal, the product has obvious beany flavor, and the eating experience is affected are solved in a targeted mode, and the technical breakthrough that the organic selenium retention rate is increased to 90% or above, the protein emulsifying activity index is larger than or equal to 85 m / g, and no peculiar smell exists is achieved.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a selenium-enriched peanut protein powder and its production process. Background Technology

[0002] Selenium, an essential trace element for the human body, participates in the synthesis of active substances such as glutathione peroxidase, and has physiological functions such as enhancing immunity, anti-oxidation, and delaying aging. 72% of my country's territory is selenium-deficient or low-selenium, making organic selenium supplementation through daily diet the safest and most effective way. Peanuts, as a globally important oilseed crop and source of plant protein, have an amino acid composition close to human needs and a good capacity for selenium accumulation. Therefore, using selenium-enriched peanuts (i.e., black peanuts) to produce peanut protein powder has significant advantages.

[0003] However, the traditional production process of selenium-enriched peanut protein powder currently suffers from the following core problems: 1. Severe loss of organic selenium: Traditional processes use high-temperature drying at 100℃~120℃ and pressing and defatting at 80℃~90℃. The high-temperature environment causes the protein-bound organic selenium to decompose into inorganic selenium (loss rate ≥30%). Inorganic selenium has low bioavailability and excessive amounts can easily produce toxicity. 2. Reduced protein activity: Single high pH (≥10) alkali extraction and high-temperature spray drying (inlet air temperature 180℃~200℃) will cause irreversible denaturation of the spatial structure of peanut protein, reducing the emulsification activity index to below 65m² / g, limiting its application in high-end foods. 3. Obvious flavor defects: The lipoxygenase contained in peanuts catalyzes unsaturated fatty acids to produce hexanal, pentanal, and other fishy-smelling substances. Traditional activated carbon adsorption or high-temperature deodorization methods either fail to completely remove the fishy smell or further damage the protein-selenium binding structure.

[0004] Therefore, developing a production process for selenium-enriched peanut protein powder that can achieve high retention of organic selenium, high protein activity, and excellent flavor and quality has become an urgent problem to be solved in the industry. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a selenium-enriched peanut protein powder and its production process, so as to overcome the defects and deficiencies of the prior art as described in the background art.

[0006] The technical solution adopted by this invention to solve its technical problem is: a process for producing selenium-enriched peanut protein powder, characterized by including the following steps: a. Raw material screening and pretreatment: Select plump, mold-free, insect-free, and selenium-rich peanut kernels with a selenium content ≥0.2mg / kg. After rinsing with purified water, dry them under vacuum conditions of 45℃~50℃ and 0.08MPa~0.1MPa until the moisture content is ≤8%. Then, send them into a peeling machine and introduce hot air at 60℃~70℃. The peeling machine's rubbing rollers remove the peanut kernels. Under the action of air separation, the seed coat of the peanut kernels is separated from the kernel, and the seed coat removal rate is ≥98%. b. Low-temperature grinding: Put the peeled peanut kernels into a liquid nitrogen low-temperature grinder, set the temperature to -10℃~-5℃ and the speed to 3000r / min~3500r / min, grind the peanut kernels and pass them through a 40-mesh standard sieve to obtain selenium-enriched peanut coarse powder with uniform particle size. c. Ultra-high pressure assisted degreasing: Selenium-enriched peanut powder and No. 6 extraction solvent oil are mixed at a material-to-liquid ratio of 1:4g / mL to 1:6g / mL and injected into an ultra-high pressure treatment chamber. The mixture is treated with an intermittent pressure mode of 300MPa to 400MPa for 5 min to 10 min. Then, it is transferred to a constant temperature water bath shaker and extracted at a temperature of 40℃ to 50℃ and an oscillation frequency of 120r / min to 150r / min for 6 h to 8 h. The extracted material is then centrifuged at 4500r / min to 5000r / min for 20 min to 25 min to obtain primary peanut meal. The primary peanut meal is then subjected to a second extraction and centrifugation process to obtain secondary peanut meal. d. Desolventizing peanut cake: Place the secondary peanut cake in a vacuum drying oven and desolventize it for 4 to 6 hours under vacuum conditions of 20℃~25℃ and 0.08MPa~0.1MPa to allow the solvent to evaporate completely. During this period, the air is changed once every 1 hour to obtain defatted peanut powder with a residual oil content of ≤2%. e. Ultrasonic-enzymatic deodorization: Add 10 times the weight of deionized water to the obtained defatted peanut powder, adjust the pH to 7.0-7.5 with 0.1 mol / L NaOH solution, add 0.2% of compound flavor protease by weight of defatted peanut powder, and then perform ultrasonic-assisted enzymatic hydrolysis for 30-35 minutes in a 50℃ constant temperature water bath using 200W power. f. Gradient alkaline extraction: Add deionized water to the deodorized material until the material-to-liquid ratio reaches 1:10 g / mL to 1:12 g / mL. Adjust the pH to 8.5 to 9.0 with 1 mol / L NaOH solution. Then extract at 40℃ with a stirring rate of 200 r / min to 250 r / min for 1 h. Subsequently, raise the temperature to 45℃, add 1 mol / L NaOH solution to adjust the pH to 9.0 to 9.5, and continue extraction for 0.5 h. g. Precise acid precipitation: Slowly adjust the pH of the extract to 4.7-4.9 with 1 mol / L HCl solution, let it stand for 1 h in a refrigerated environment at 4℃, and collect the protein precipitate by centrifugation at 5000 r / min for 15 min; h. Washing and freeze-drying: Wash the protein precipitate repeatedly with deionized water 3-4 times until the pH of the washing solution is 6.5-7.0; place the washed precipitate in a freeze dryer and freeze-dry it at -40℃ and 10-20Pa vacuum for 12 hours to obtain crude selenium-enriched peanut protein powder. i. Ultrafine grinding and packaging: The coarse product is fed into an ultrafine grinder (grinding fineness 100 mesh), and after grinding, it is packaged in an aluminum-plastic composite bag filled with nitrogen (nitrogen purity ≥99.99%, residual oxygen rate ≤1%) to obtain the finished product.

[0007] A selenium-enriched peanut protein powder is produced using the above-mentioned production process.

[0008] The beneficial effects of this invention are: high organic selenium retention rate: the temperature throughout the process is ≤60℃, and combined with the gradient extraction process, the organic selenium loss rate is ≤10%, and the organic selenium content of the finished product is ≥90%, which is far higher than the level of less than 70% in existing processes. Excellent protein activity: protein purity ≥92%, emulsification activity index ≥85m² / g, solubility ≥80%, meeting the standards for food-grade high-protein powder. Good flavor and safety: After ultrasonic-enzymatic deodorization, the product has no beany smell, and the solvent residue is ≤5mg / kg, which meets the GB 2760 food safety standard. High production efficiency: The entire production cycle is ≤24 hours, which is more than 60% shorter than the peanut sprout process, making it suitable for industrial mass production.

[0009] The retention rate of organic selenium is significantly improved: the whole process is controlled at low temperature (≤60℃) and combined with gradient extraction process, so that the organic selenium loss rate is ≤10% and the organic selenium content of the finished product is ≥90%, which is far higher than the level of less than 70% of the existing process; the total selenium content is ≥0.3mg / kg, which meets the standard of "selenium-enriched food" (≥0.15mg / kg) in GB 28050-2011 "General Rules for Nutrition Labelling of Prepackaged Foods".

[0010] Excellent protein activity and purity: Protein purity ≥92%, far exceeding the industry standard of 85%; emulsification activity index ≥85m² / g, solubility ≥80%, meeting the requirements of high-end foods (such as infant formula) for protein functional properties; SDS-PAGE electrophoresis detection shows that the relative content of 7S and 11S globulins in the finished product remains at about 3:7, consistent with the composition of natural peanut protein, proving that the protein structure has not been damaged.

[0011] Flavor and safety meet standards: After ultrasonic-enzymatic deodorization, the product was tested by gas chromatography-mass spectrometry (GC-MS) and the hexanal content was ≤0.1mg / kg (≥0.5mg / kg in traditional processes), with no obvious beany odor; the solvent residue was ≤5mg / kg, which meets the requirements of GB 2760-2024 "National Food Safety Standard for the Use of Food Additives"; the heavy metal (lead, arsenic, mercury) content was ≤0.01mg / kg, meeting the safety standards for health food products.

[0012] High production efficiency and controllable cost: The entire production cycle is ≤24 hours, which is more than 60% shorter than the peanut sprout selenium enrichment process (7-10 days); the ultra-high pressure degreasing and gradient alkali extraction technology reduces the amount of solvents and reagents used, reducing production costs by 15-20%, making it suitable for large-scale industrial production. Detailed Implementation

[0013] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are only some, not all, of the embodiments described herein.

[0014] Example 1 (Adjustment rate: 0.5 pH / h) Example 2 Example 1 (Optimal Parameter Combination) 1. Raw material pretreatment: Select natural selenium-rich peanuts from Enshi, Hubei (total selenium 0.25mg / kg, mold rate 0.3%), remove the shells and dry them in a vacuum at 48℃ and 0.1MPa for 5h (moisture content 7.2%). Use hot air at 90℃ (wind speed 18m / s) to vortex remove the skins for 6min to obtain skinless peanut kernels.

[0015] Low-temperature grinding: The liquid nitrogen low-temperature grinder is set at a temperature of -7℃ and a speed of 3200r / min. After grinding, the peanut powder passes through a 40-mesh sieve and has a uniform particle size (passing rate of 98%).

[0016] Ultra-high pressure degreasing: Peanut coarse powder and No. 6 solvent oil were mixed at a material-to-liquid ratio of 1:5 g / mL, and treated intermittently at 350 MPa (2 min / time, 3 cycles); extracted in a constant temperature water bath shaker at 45℃ (140 r / min) for 7 h, and the cakes were combined after centrifugation (residual oil rate 1.8%).

[0017] Desolventization and deodorization: Desolventize under vacuum at room temperature for 5 hours (solvent residue 4.1 mg / kg); add 10 times the amount of deionized water, adjust pH to 7.2, add 0.2% flavor protease, and enzymatically hydrolyze under 200W pulsed ultrasound at 50℃ for 30 minutes (hexanal content 0.08 mg / kg).

[0018] Gradient alkali extraction and acid precipitation: The ratio of the conditioning solution to the alkali solution is 1:11. First, extract at pH 8.8 and 40℃ for 1 hour, then extract at pH 9.2 and 45℃ for 0.5 hours. Adjust the pH to 4.8 with HCl, let stand at 4℃ for 1 hour, and collect the precipitate by centrifugation.

[0019] Drying and packaging: Wash to pH 6.8, freeze dry at -40℃ and 15Pa for 12 hours; ultrafine pulverize to 100 mesh, and package with nitrogen filling (residual oxygen rate 0.8%).

[0020] Finished product test results: total selenium 0.48 mg / kg, organic selenium 0.44 mg / kg (accounting for 91.7%), protein purity 93.2%, emulsification activity index 88 m² / g, solubility 82%, solvent residue 3.2 mg / kg, heavy metals not detected, no bean smell.

[0021] Example 2 (Parameter Adjustment Verification) The ultra-high pressure was adjusted to 400 MPa, the pH of the alkali extraction was 8.5 / 9.0, and the other parameters were the same as in Example 1.

[0022] Finished product test results: total selenium 0.46 mg / kg, organic selenium 0.42 mg / kg (accounting for 91.3%), protein purity 92.5%, emulsification activity index 86 m² / g, solubility 80%, meeting product quality standards.

[0023] Comparative Example (Comparison with Traditional Processes) Traditional process is used: 100℃ hot air drying, room temperature mechanical pulverization, 80℃ pressing and degreasing, single pH 9.5 alkali extraction, and 180℃ spray drying.

[0024] The finished product test results showed that the total selenium content was 0.32 mg / kg, the organic selenium content was 0.22 mg / kg (accounting for 68.8%), the protein purity was 84.6%, the emulsification activity index was 62 m² / g, the solubility was 65%, and the hexanal content was 0.6 mg / kg (with a distinct fishy smell), demonstrating the significant advantages of the process of this invention.

[0025] Description of Detailed Implementation Raw material selection: Peanuts from naturally selenium-rich planting bases (such as Enshi, Hubei and Ziyang, Shaanxi) should be given priority. If artificially selenium-enriched peanuts are used, the selenium enrichment process must comply with GB / T 224. The above embodiments are only used to explain the present invention and are not intended to limit the protection of the present invention. Any non-substantial modifications made based on the essential solution of the present invention should fall within the protection scope of the present invention.

Claims

1. A manufacturing process for selenium-enriched peanut protein powder, characterized in that: Includes the following steps: a. Raw material screening and pretreatment: Select plump, mold-free, insect-free, and selenium-rich peanut kernels with a selenium content ≥0.2mg / kg. After rinsing with purified water, dry them under vacuum conditions of 45℃~50℃ and 0.08MPa~0.1MPa until the moisture content is ≤8%. Then, send them into a peeling machine and introduce hot air at 60℃~70℃. The peeling machine's rubbing rollers remove the peanut kernels. Under the action of air separation, the seed coat of the peanut kernels is separated from the kernel, and the seed coat removal rate is ≥98%. b. Low-temperature grinding: Put the peeled peanut kernels into a liquid nitrogen low-temperature grinder, set the temperature to -10℃~-5℃ and the speed to 3000r / min~3500r / min, grind the peanut kernels and pass them through a 40-mesh standard sieve to obtain selenium-enriched peanut coarse powder with uniform particle size. c. Ultra-high pressure assisted degreasing: Selenium-enriched peanut powder and No. 6 extraction solvent oil are mixed at a material-to-liquid ratio of 1:4g / mL to 1:6g / mL and injected into an ultra-high pressure treatment chamber. The mixture is treated with an intermittent pressure mode of 300MPa to 400MPa for 5 min to 10 min. Then, it is transferred to a constant temperature water bath shaker and extracted at a temperature of 40℃ to 50℃ and an oscillation frequency of 120r / min to 150r / min for 6 h to 8 h. The extracted material is then centrifuged at 4500r / min to 5000r / min for 20 min to 25 min to obtain primary peanut meal. The primary peanut meal is then subjected to a second extraction and centrifugation process to obtain secondary peanut meal. d. Desolventizing peanut cake: Place the secondary peanut cake in a vacuum drying oven and desolventize it for 4 to 6 hours under vacuum conditions of 20℃~25℃ and 0.08MPa~0.1MPa to allow the solvent to evaporate completely. During this period, the air is changed once every 1 hour to obtain defatted peanut powder with a residual oil content of ≤2%. e. Ultrasonic-enzymatic deodorization: Add 10 times the weight of deionized water to the obtained defatted peanut powder, adjust the pH to 7.0-7.5 with 0.1 mol / L NaOH solution, add 0.2% of compound flavor protease by weight of defatted peanut powder, and then perform ultrasonic-assisted enzymatic hydrolysis for 30-35 minutes in a 50℃ constant temperature water bath using 200W power. f. Gradient alkaline extraction: Add deionized water to the deodorized material until the material-to-liquid ratio reaches 1:10 g / mL to 1:12 g / mL. Adjust the pH to 8.5 to 9.0 with 1 mol / L NaOH solution. Then extract at 40℃ with a stirring rate of 200 r / min to 250 r / min for 1 h. Subsequently, raise the temperature to 45℃, add 1 mol / L NaOH solution to adjust the pH to 9.0 to 9.5, and continue extraction for 0.5 h. g. Precise acid precipitation: Slowly adjust the pH of the extract to 4.7-4.9 with 1 mol / L HCl solution, let it stand for 1 h in a refrigerated environment at 4℃, and collect the protein precipitate by centrifugation at 5000 r / min for 15 min; h. Washing and freeze-drying: Wash the protein precipitate repeatedly with deionized water 3-4 times until the pH of the washing solution is 6.5-7.0; place the washed precipitate in a freeze dryer and freeze-dry it at -40℃ and 10-20Pa vacuum for 12 hours to obtain crude selenium-enriched peanut protein powder. i. Ultrafine grinding and packaging: The coarse product is fed into an ultrafine grinder (grinding fineness 100 mesh), and after grinding, it is packaged in an aluminum-plastic composite bag filled with nitrogen (nitrogen purity ≥99.99%, residual oxygen rate ≤1%) to obtain the finished product.

2. A selenium-enriched peanut protein powder, characterized in that: Made by the manufacturing process described in claim 1.