Low-fat flavored peanuts and preparation method thereof

Abstract

The invention provides low-fat flavored peanuts and a preparation method thereof, and belongs to the technical field of food processing. The preparation method comprises the following steps: squeezing and degreasing peanut kernels to obtain degreased peanuts; dissolving sucrase and alkaline protease in a buffer solution to obtain an enzymatic hydrolysate with a pH value of 3-9; soaking the degreased peanuts in an enzymatic hydrolysate, pouring out the enzymatic hydrolysate, and performing enzymolysis to obtain degreased peanuts after enzymolysis; and drying the degreased peanuts after enzymolysis, and frying seeds to obtain the low-fat flavored peanuts. According to the preparation method, fat can be reduced, heat-sensitive nutritional ingredients in the peanuts can be reserved to a large extent, the content of total reducing sugar, total amino acid and total volatile ingredients is remarkably increased, meanwhile, formation of harmful risk ingredients can be prevented and controlled, energy consumption is reduced, exogenous flavor precursor substances do not need to be added, and the preparation method is environmentally friendly. The peanuts with rich sweet fragrance are prepared. The preparation method is simple in technological process and good in technological applicability.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to low-fat flavored peanuts and a preparation method thereof. Background Art

[0002] Peanuts are rich in protein, fat, carbohydrates, vitamins B1, B2, B3, A, D, and E, and minerals such as calcium, phosphorus, and iron. They are known for their nourishing and longevity-promoting properties, earning them the nickname "longevity fruit." Peanuts are a nutritious food rich in unsaturated fatty acids, fiber, vitamins, minerals, and a variety of bioactive substances, such as polyphenols, phytosterols, triterpenes, and alkaloids, offering numerous health benefits. Due to the complex nature of peanut processing, different methods produce varying flavors. With rising living standards, consumer demand for peanut products with enhanced flavor, nutritional value, and safety is increasing.

[0003] While boiled peanuts cooked and shelled in a pressure cooker can effectively preserve the active ingredients in peanuts, such as phytosterols, saponins, and resveratrol, they have a bland taste and lack a rich aroma, making them difficult to satisfy consumers' preference for flavorful peanut products. On the other hand, peanuts can be eaten directly after simple processing, such as roasting, which not only enhances their color and aroma but also reduces their allergen content. Roasting peanuts, with its pleasant texture and rich flavor, has become one of the most popular processing methods. However, despite its popularity, roasted peanuts are also high in fat. With the growing demand for nutritional health, low-fat processing methods are gaining attention, aiming to reduce fat content while retaining the good flavor and texture of peanuts. Common methods include mechanical pressing, organic solvent extraction, enzyme treatment, and supercritical fluid extraction. Mechanical pressing is characterized by its simplicity, low production cost, and lack of chemical residue risk. Limited defatted peanuts are a byproduct of mechanical pressing during peanut oil production. Utilizing restricted defatted peanuts as a raw material for low-fat peanut snack production has been shown to significantly improve the processing efficiency of defatted by-products, thereby increasing the economic value of peanuts and boosting the profitability of the company.

[0004] However, current peanut processing methods often reduce the oil content, resulting in a weakened peanut flavor. Peanut kernels also contain a high sucrose content. Therefore, in the hot-pressing method, sucrose participates in the Maillard reaction primarily through high-temperature degradation before participating in the reaction. Therefore, the temperature is typically high (e.g., 180°C or even higher) and the roasting time is typically long (e.g., 90 minutes). While this high-temperature, long-term roasting process can achieve a fragrant aroma, it also results in a strong burnt flavor in the roasted peanut kernels. Furthermore, peanut skins are rich in tannins and polyphenols, which are easily oxidized during heating, producing a bitter taste. Traditional processing of roasted peanut products typically involves high temperatures (e.g., 180-200°C) and long heating times (30-60 minutes), which can lead to the loss of heat-sensitive nutrients. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a low-fat flavored peanut and a preparation method thereof, wherein the low-fat flavored peanut prepared by the preparation method can retain the heat-sensitive nutrients in the peanut to a large extent.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing low-fat flavored peanuts, comprising the following steps:

[0008] Pressing and defatting the peanut kernels to obtain defatted peanuts;

[0009] Dissolving sucrase and alkaline protease in a buffer solution to obtain an enzymatic hydrolyzate having a pH of 3 to 9;

[0010] soaking the defatted peanuts in an enzymatic hydrolysis solution, pouring out the enzymatic hydrolysis solution, and performing enzymatic hydrolysis to obtain enzymatically hydrolyzed defatted peanuts;

[0011] The defatted peanuts after enzymatic hydrolysis are dried and the seeds are roasted to obtain low-fat flavored peanuts.

[0012] Preferably, the pressing pressure is 10 to 60 MPa, and the pressing time is 0.5 to 1.5 h.

[0013] Preferably, the mass ratio of the sucrase to the alkaline protease is 1:(4-6); the mass volume ratio of the sucrase to the buffer is (0.05-1) g:100 mL; the mass volume ratio of the alkaline protease to the buffer is (0.05-1) g:100 mL.

[0014] Preferably, the mass volume ratio of the defatted peanuts to the enzymatic hydrolysis solution is 1 g: (1-3) mL.

[0015] Preferably, the soaking temperature is 45° C. to 60° C., and the soaking time is 5 to 40 minutes.

[0016] Preferably, the enzymatic hydrolysis temperature is 45° C. to 60° C., and the enzymatic hydrolysis time is 0.5 to 4 hours.

[0017] Preferably, the temperature for frying the seeds is 120° C. to 160° C., and the time for frying the seeds is 10 to 50 minutes.

[0018] Preferably, oven drying or blast drying is adopted, the drying temperature is 30-55° C., and the drying time is 8-12 hours.

[0019] The present invention provides low-fat flavored peanuts prepared by the above-mentioned preparation method.

[0020] Preferably, the low-fat flavored peanuts have high contents of total reducing sugars, total amino acids and total volatile components.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides low-fat flavored peanuts and a preparation method thereof. This preparation method reduces fat while largely retaining heat-sensitive nutrients in the peanuts. This preparation method significantly increases the content of total reducing sugars, total amino acids, and total volatile components, while also preventing and controlling the formation of harmful risk components and reducing energy consumption. The method eliminates the need for adding exogenous flavor precursors, resulting in peanuts with a rich, sweet aroma. This preparation method has a simple process flow and good process applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the process for preparing low-fat flavored peanuts by enzymatic hydrolysis.

[0024] Figure 2 Comparison of total reducing sugar content in flavored peanuts prepared from different groups;

[0025] Figure 3 Comparison of total amino acid content in flavored peanuts prepared for different groups;

[0026] Figure 4 Comparison of the volatile component content in flavored peanuts prepared from different groups. DETAILED DESCRIPTION

[0027] The present invention provides a method for preparing low-fat flavored peanuts, comprising the following steps:

[0028] Pressing and defatting the peanut kernels to obtain defatted peanuts;

[0029] Dissolving sucrase and alkaline protease in a buffer solution to obtain an enzymatic hydrolyzate having a pH of 3 to 9;

[0030] soaking the defatted peanuts in an enzymatic hydrolysis solution, pouring out the enzymatic hydrolysis solution, and performing enzymatic hydrolysis to obtain enzymatically hydrolyzed defatted peanuts;

[0031] The defatted peanuts after enzymatic hydrolysis are dried and the seeds are roasted to obtain low-fat flavored peanuts.

[0032] In the present invention, peanut kernels are pressed and defatted to produce defatted peanuts. The pressing pressure is preferably 10-60 MPa, more preferably 30-50 MPa, and even more preferably 30, 40, or 50 MPa; the pressing time is preferably 0.5-1.5 hours, even more preferably 1 hour. The pressing temperature is room temperature, which is 22-28°C, even more preferably 23-27°C, and even more preferably 25°C. The present invention utilizes hydraulic technology to defatt the peanuts. Hydraulic technology utilizes liquid pressure to process materials. In the present invention, the oil in the peanuts is squeezed out by applying a certain amount of hydraulic pressure. This method offers higher efficiency and lower energy consumption than traditional mechanical pressing or chemical extraction methods. This innovative technology not only efficiently separates defatted peanut kernels but also simultaneously produces high-quality cold-pressed peanut oil, achieving efficient utilization of peanut resources while balancing product quality and production efficiency. The present invention utilizes this pressing method to significantly increase the content of total reducing sugars, total amino acids, and total volatile components.

[0033] In the present invention, after obtaining defatted peanuts, sucrase and alkaline protease are dissolved in a buffer solution to obtain an enzymatic hydrolyzate with a pH of 3 to 9. The mass ratio of the sucrase to the alkaline protease is preferably 1:(4-6), more preferably 1:(4.5-5.5), and more preferably 1:5; the mass volume ratio of the sucrase to the buffer solution is preferably (0.05-1) g:100 mL, more preferably (0.1-1) g:100 mL, more preferably 0.1 g:100 mL, 0.5 g:100 mL, or 1 g:100 mL; the mass volume ratio of the alkaline protease to the buffer solution is preferably (0.05-1) g:100 mL, more preferably (0.1-0.5) g:100 mL, and more preferably 0.1 g:100 mL or 0.5 g:100 mL. The preparation method of the phosphate-citrate buffer is as follows: prepare 0.1 mol / L citric acid solution (weigh 21.014 g of citric acid monohydrate, dilute to 1 L with deionized water to obtain 0.2 mol / L citric acid solution) and 0.2 mol / L disodium hydrogen phosphate (Na2HPO4) solution (weigh 71.628 g of disodium hydrogen phosphate dodecahydrate, dilute to 1 L with deionized water to obtain 0.2 mol / L disodium hydrogen phosphate solution), and mix the above two solutions according to the target pH value according to the ratio relationship known in the art to obtain a phosphate-citrate buffer of the desired pH. The pH of the enzymatic hydrolyzate is 4 to 8, more preferably 4.5, 6 or 7. The mass volume ratio of the defatted peanuts to the enzymatic hydrolyzate is 1 g: (1 to 3) mL, more preferably 1 g: 1 mL or 1 g: 3 mL. The enzymatic hydrolysis temperature is preferably 45°C to 60°C, more preferably 50°C to 55°C, and more preferably 55°C; the enzymatic hydrolysis time is 0.5 to 4 hours, more preferably 1 to 3 hours, and more preferably 3 hours. The present invention has found that compared with the preparation of low-fat flavored peanuts by simply adding sucrase or alkaline protease for enzymatic hydrolysis, the co-enzymatic hydrolysis using sucrase and alkaline protease can significantly increase the content of total reducing sugars, total amino acids, and total volatile components. Total reducing sugars and total amino acids are the precursor flavor substances of low-fat flavored peanuts. The present invention can promote the production of more volatile flavor components during the heat treatment process without the need to add additional exogenous flavor precursors.

[0034] In the present invention, after obtaining an enzymatic hydrolysis solution with a pH of 3 to 9, the defatted peanuts are soaked in the enzymatic hydrolysis solution. After the enzymatic hydrolysis solution is removed, enzymatic hydrolysis is performed to obtain enzymatically hydrolyzed defatted peanuts. The soaking temperature is preferably 45°C to 60°C, more preferably 50°C to 55°C, and more preferably 55°C; the soaking time is preferably 5 to 40 minutes, more preferably 10 to 30 minutes, and more preferably 30 minutes. During the peanut soaking process, water penetration softens and expands the cell wall structure of the peanut kernel, thereby improving enzyme permeability and substrate accessibility, effectively enhancing enzymatic hydrolysis efficiency. Simultaneously, soaking promotes the diffusion of water-soluble components within the peanut kernel, providing a more favorable reaction environment for subsequent enzymatic hydrolysis reactions. Peanut skins are primarily composed of cellulose, lignin, and polyphenols. During the soaking process, water gradually penetrates the tissue, softening the cell wall and seed coat structure. Simultaneously, the skin absorbs water and expands, weakening its bond to the kernel, creating favorable conditions for removal. On this basis, efficient peeling can be achieved through moderate scrubbing or mechanical methods (such as air flow separation, drum friction, centrifugal peeling, wind classification or vibration peeling, etc.). This process not only helps to remove polyphenols in the red coat that may affect the flavor, reduce bitterness and astringency, but also improves the taste, enhances the sensory quality and nutritional value of the product. The removal of the red coat not only reduces bitterness and inhibitory factors, but also further promotes the penetration of the enzyme and contact with the substrate, thereby improving the enzymatic hydrolysis efficiency and improving the product flavor. This process not only improves the enzymatic hydrolysis efficiency, but also simplifies the red coat removal process, improves processing efficiency, and makes the product more advantageous in flavor, color and texture.

[0035] In the present invention, after obtaining enzymatically hydrolyzed defatted peanuts, the enzymatically hydrolyzed defatted peanuts are dried and roasted to produce low-fat flavored peanuts. The roasting temperature is 120°C to 160°C, more preferably 130°C to 160°C, and even more preferably 130, 140, 150, or 160°C; the roasting time is preferably 10 to 50 minutes, and even more preferably 10 minutes. The drying temperature is preferably 30 to 55°C, more preferably 32 to 50°C, and even more preferably 35, 36, 37, 38, 39, or 40°C; the drying time is preferably 8 to 12 hours, more preferably 9 to 11 hours, and even more preferably 10 hours. This method achieves the purpose of heat-processing the roasted seeds to produce aroma at a lower temperature and in a shorter time, avoiding the drawbacks of high-temperature heat treatment, such as the production of burnt peanuts and risky polycyclic aromatic hydrocarbons, severe protein damage in the peanuts, and high energy consumption. The resulting low-fat flavored peanuts have a unique sweet aroma and higher nutritional value. All product indicators meet national standards, demonstrating high economic value and market prospects.

[0036] The present invention preserves the integrity of the peanuts through defatting and enzymatic hydrolysis. This means the peanut kernels are not excessively broken during processing, thus maintaining their natural taste and appearance. This integrity not only improves product quality but also enhances consumer acceptance, as consumers generally prefer products that look and taste more like natural ingredients.

[0037] The present invention provides low-fat flavored peanuts prepared by the above-mentioned preparation method.

[0038] In the present invention, the low-fat flavored peanuts have high contents of total reducing sugars, total amino acids and total volatile components. The low-fat flavored peanuts are low-fat, highly nutritious, safe and healthy peanuts.

[0039] The present invention combines restricted pressing defatting with enzymatic flavoring technology to reduce fat content while maintaining its excellent flavor. The present invention adopts a dry enzymatic hydrolysis process, which creates favorable conditions for the removal of the red skin while achieving the enzymatic reaction, effectively reducing the release of bitter substances (such as polyphenols) in the red skin in the system, reducing the bitterness, and thus significantly optimizing the flavor performance and overall quality of the peanut product. The present invention adopts enzymatic treatment to effectively reduce the roasting temperature and roasting time, while effectively retaining heat-sensitive active nutrients, optimizing the safety and flavor quality of the product.

[0040] In the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0041] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0042] In the following examples, the room temperature refers to 25°C.

[0043] Example 1

[0044] A method for preparing low-fat flavored peanuts using an enzymatic method, comprising the following steps:

[0045] 500g of high-quality, mature, and mold-free peanut kernels were selected as the raw material and pressed in a hydraulic oil press at 10 MPa, room temperature, and for 1 hour. The defatted peanuts were collected to obtain the enzymatic hydrolysis material. 1.5g of sucrase and 7.5g of alkaline protease were dissolved in 1500mL of phosphate-citrate buffer (pH 6). The defatted peanuts were then soaked in 1500mL of the enzymatic hydrolysis solution at 55°C for 30 minutes. The solution was then removed and enzymatic hydrolysis was continued at 55°C for 3 hours to obtain the defatted peanut kernels. The defatted peanut kernels were then dried at 40°C for 10 hours and roasted in a seed roaster at 160°C for 15 minutes to produce defatted sweet-flavored peanuts, also known as low-fat flavored peanuts.

[0046] Figure 1 Schematic diagram of the process for preparing low-fat flavored peanuts by enzymatic hydrolysis.

[0047] Example 2

[0048] The difference between this embodiment and embodiment 1 is that the oil in this embodiment is pressed at 30 MPa by a hydraulic oil press, and the remaining steps are the same as those in embodiment 1.

[0049] Example 3

[0050] The difference between this embodiment and embodiment 1 is that the oil in this embodiment is pressed at 40 MPa by a hydraulic oil press, and the remaining steps are the same as those in embodiment 1.

[0051] Example 4

[0052] The difference between this embodiment and embodiment 1 is that the oil in this embodiment is pressed at 60 MPa by a hydraulic oil press, and the remaining steps are the same as those in embodiment 1.

[0053] Example 5

[0054] The difference between this embodiment and embodiment 2 is that in this embodiment, the dried peanut kernel raw material is placed in a seed roaster at 140° C. and roasted for 15 minutes, and the remaining steps are the same as those in embodiment 2.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that this comparative example is a non-defatted enzymatically hydrolyzed group, that is, the preparation method of the flavored peanuts in this comparative example comprises the following steps:

[0057] Select 500g of high-quality, mature, and undeteriorated peanut kernels as the raw material. Dissolve 1.5g of sucrase and 7.5g of alkaline protease in 1500mL of phosphate-citrate buffer at pH 6. Then soak the peanut kernels in 1500mL of enzymatic hydrolysis solution at 55°C for 30 minutes. After that, remove the enzymatic hydrolysis solution and continue enzymatic hydrolysis at 55°C for 3 hours to obtain the enzymatically hydrolyzed, un-defatted peanut kernels. Dry the enzymatically hydrolyzed, un-defatted peanut kernels at 40°C for 10 hours. Then, roast the dried peanut kernels in a seed roaster at 160°C for 15 minutes to produce the flavored peanuts.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 1 is that this comparative example is a defatted and non-enzymatically hydrolyzed group, that is, the preparation method of the flavored peanuts in this comparative example comprises the following steps:

[0060] 500g of high-quality, mature, and mold-free peanut kernels were selected as the raw material. These were pressed in a hydraulic press at 30 MPa, room temperature, and for one hour. The defatted peanuts were then roasted in a roaster at 160°C for 15 minutes to produce the flavored peanuts.

[0061] Comparative Example 3

[0062] This comparative example is to carry out enzymatic hydrolysis first and then carry out defatting.

[0063] The preparation method of the flavored peanuts of this comparative example comprises the following steps:

[0064] Select 500g of high-quality, mature, non-deteriorated and non-mildewed peanut kernels as raw materials.

[0065] Dissolve 1.5g of sucrase and 7.5g of alkaline protease in 1500mL of phosphate-citrate buffer at pH 6. Then, soak the peanut kernels in 1500mL of enzymatic hydrolysis solution at 55°C for 30 minutes. The solution is then removed and enzymatic hydrolysis is continued at 55°C for 3 hours to obtain enzymatically hydrolyzed peanut kernels. The enzymatically hydrolyzed peanut kernels are then pressed in a hydraulic press at 30MPa at room temperature for 1 hour to obtain enzymatically hydrolyzed defatted peanut kernels. The enzymatically hydrolyzed defatted peanut kernels are then oven-dried at 40°C for 10 hours and roasted in a seed roaster at 160°C for 15 minutes to produce flavored peanuts.

[0066] Comparative Example 4

[0067] Compared with Example 2, this comparative example only used sucrase enzymolysis and did not use alkaline protease.

[0068] The preparation method of the flavored peanuts of this comparative example comprises the following steps:

[0069] 500g of high-quality, mature, and undeteriorated peanut kernels were selected as the raw material and pressed using a hydraulic press at 30MPa, room temperature, and for 1 hour. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 0.5g of sucrase was dissolved in 500mL of phosphate-citrate buffer (pH 4.5). The defatted peanuts were then soaked in 500mL of the enzymatic hydrolysis solution at 55°C for 30 minutes. The solution was then removed and enzymatic hydrolysis was continued at 55°C for 3 hours to obtain the defatted peanut kernels. The defatted peanut kernels were then dried at 40°C for 10 hours and then roasted in a seed roaster at 160°C for 15 minutes to produce the flavored peanuts.

[0070] Comparative Example 5

[0071] Compared with Example 2, this comparative example only used alkaline protease for enzymatic hydrolysis, without using sucrase.

[0072] The preparation method of the flavored peanuts of this comparative example comprises the following steps:

[0073] 500g of high-quality, mature, and undeteriorated peanut kernels were selected as the raw material and pressed using a hydraulic oil press at 30MPa, room temperature, and for 1 hour. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 0.5g of alkaline protease was dissolved in 1500mL of phosphate-citrate buffer at pH 7. The defatted peanuts were then soaked in 1500mL of the enzymatic hydrolysis solution at 55°C for 30 minutes. The solution was then removed and enzymatic hydrolysis was continued at 55°C for 3 hours to obtain the defatted peanut kernels. The defatted peanut kernels were then dried at 40°C for 10 hours and then roasted in a seed roaster at 160°C for 15 minutes to produce the flavored peanuts.

[0074] Comparative Example 6

[0075] The difference between this comparative example and Example 2 is that in this comparative example, the dried peanut kernel raw material is placed in a seed roaster at 160° C. and roasted for 40 minutes, and the remaining steps are the same as in Example 2.

[0076] Comparative Example 7

[0077] The preparation method of the flavored peanuts of this comparative example comprises the following steps:

[0078] 500g of high-quality, mature, and undeteriorated peanut kernels were selected and pressed in a hydraulic oil press at 30MPa, room temperature, and for 1 hour. The defatted peanuts were collected to obtain the hydrolysis raw material. The raw material was added to 1500mL of phosphate-citrate buffer at pH 6. The defatted peanuts were then soaked in the buffer at 55°C for 30 minutes. The buffer was then removed and the peanuts were hydrolyzed at 55°C for 3 hours to obtain the hydrolyzed defatted peanut kernels. The hydrolyzed defatted peanut kernels were then dried at 40°C for 10 hours and roasted in a seed roaster at 160°C for 15 minutes to produce the flavored peanuts.

[0079] Comparative Example 8

[0080] The preparation method of the flavored peanuts of this comparative example comprises the following steps:

[0081] Select 500g of high-quality, mature, and non-deteriorated peanut kernels. Add the undefatted peanuts to 1500mL of a pH 6 phosphate-citrate buffer solution at 55°C for 30 minutes. After the buffer is removed, hydrolyze the peanuts at 55°C for 3 hours to obtain hydrolyzed undefatted peanut kernels. Dry the hydrolyzed undefatted peanut kernels at 40°C for 10 hours. Then, roast the dried peanut kernels in a seed roaster at 160°C for 15 minutes to obtain peanuts.

[0082] Comparative Example 9

[0083] The preparation method of the flavored peanuts of this comparative example comprises the following steps:

[0084] Select 500g of high-quality, mature, non-deteriorated, and mold-free peanut kernels. Roast them in a peanut roaster at 160°C for 15 minutes without enzymatic hydrolysis to produce flavored peanuts.

[0085] Test Example 1

[0086] The low-fat flavored peanuts prepared in Examples 1 to 6 and the flavored peanuts prepared in Comparative Examples 1 to 5 were tested for total reducing sugar content, total amino acid content, and total volatile component content.

[0087] 1. Determination of total reducing sugar

[0088] Accurately weigh 1.0 g of ground raw material and place it in a 50 mL centrifuge tube, then add 20.0 mL of petroleum ether. Use a multipoint oscillator to defatted the mixture at a speed of 2000 rpm for 10.0 minutes. After defatting, the sample was centrifuged in a refrigerated centrifuge at a speed of 4000 rpm at 15.0 ° C for 10.0 minutes. The petroleum ether was then decanted. The defatting procedure was repeated twice, and the residual petroleum ether was evaporated under a stream of nitrogen. The defatted sample was then transferred to 20.0 mL of 50.0% ethanol-water solution and subjected to ultrasound-assisted extraction for 1.0 h. After extraction, the sample was centrifuged at 4000 rpm at 10.0 ° C for 10.0 minutes. The supernatant (4.0 mL) was transferred to a 10 mL centrifuge tube, 0.2 mL of 15.0% potassium ferrocyanide solution was added, and then gently shaken. Subsequently, 0.2 mL of 30.0% zinc sulfate solution was added and the mixture was vortexed thoroughly. The sample was then centrifuged at 10,000 rpm for 10 minutes at 10°C. After centrifugation, the lower phase was collected and filtered through a 0.22 μm PTFE membrane. The filtrate was then prepared for subsequent analysis. Chromatographic analysis was performed using a PrevailCarbohydrate ES 5 μm column. The mobile phase consisted of acetonitrile (A) and purified water (B). The gradient elution program was as follows: 85% A from 0.0 to 5.0 minutes; 85% to 70% A from 5.0 to 20.0 minutes; 70% to 60% A from 20.0 to 25.0 minutes; 60% to 50% A from 25.0 to 30.0 minutes; 50% to 85% A from 30.0 to 35.0 minutes; and 85% A from 35.0 to 40.0 minutes. The flow rate was set at 1.0 mL / min, and the column temperature was maintained at 35.0°C. Analyses were performed using a 10.0 μL injection volume.

[0089] 2. Determination of total amino acid content

[0090] Free amino acids were extracted and quantified using an amino acid analyzer according to the Chinese Food Safety Standard GB 5009.124-2016, "Determination of Amino Acids in Food," with minor modifications. Defatted peanut flour was accurately weighed and placed in a 50.0 mL centrifuge tube. Extraction was performed with 15.0 mL of 0.01 mol / L hydrochloric acid, followed by incubation for 30.0 minutes. This step was repeated twice. After each extraction, the mixture was centrifuged at 4000.0 rpm for 10.0 minutes, and the resulting supernatants were combined. A 2.0 mL aliquot of the combined extract was mixed with 2.0 mL of 4.0% sulfosalicylic acid solution, and the mixture was allowed to stand in the dark for 15.0 minutes to precipitate proteins. The sample was then centrifuged at 10,000.0 rpm for 15.0 minutes. The final supernatant was filtered through a 0.22 μm membrane filter and transferred to an autosampler vial for subsequent instrumental analysis.

[0091] 3. Determination of total volatile components

[0092] Headspace solid-phase microextraction (HS-SPME) is considered a rapid and effective technique for volatile compound analysis. A 2.00 g peanut sample was accurately weighed and placed in a 20 mL headspace vial. 100 μL of internal standard solution (4-nonanol, 0.4 mg / mL) was added to the vial. The vial was sealed with a polytetrafluoroethylene (PTFE) / silicone septum. The vial was held upright and gently rolled on a horizontal surface to ensure thorough mixing while preventing the peanuts from coming into contact with the septum during rotation. Mass spectrometry parameters were set as follows: extraction was performed using a divinylbenzene / carboxyolefin / polydimethylsiloxane (DVB / CAR / PDMS) fiber tip (2 cm long, 50 / 30 μm thick), with a GC cycle time of 62 minutes. The heated shaker was agitated for 40 minutes, with the stirring speed maintained at 200 rpm and the oscillation speed set to 500 rpm. Sample extraction was performed at an extraction temperature of 60°C for 30 minutes, followed by sample desorption for 5 minutes. Aging was performed at 250°C for 5 minutes.

[0093] Table 1 Test results of total reducing sugar, total amino acid and total volatile component contents in different groups

[0094]

[0095]

[0096] according to Figure 2 、 Figure 3 The results in Table 1 show that the total reducing sugar, total amino acid, and total volatile component contents of the low-fat flavored peanuts in Example 1 were significantly higher than those in the non-defatted enzymatic hydrolysis group of Comparative Example 1 and the defatted non-enzymatic hydrolysis group of Comparative Example 2, but lower than those in Examples 2 to 4. This indicates that by using alkaline protease and sucrase to perform dry enzymatic hydrolysis on defatted peanut kernels prepared under different restrictive pressures, peanuts with good flavor that meet the national standard "SB / T 10614-2011 Cooked Peanuts (Kernels)" can be produced even at lower heat treatment temperatures and shorter heat treatment times (compared to directly heating the peanut raw materials, Comparative Example 9), and heat-sensitive nutrients in the peanuts can be retained without harmful risk components, thereby avoiding serious damage to the raw material protein.

[0097] Compared with Comparative Example 4 (enzymatic hydrolysis with sucrase alone) and Comparative Example 5 (enzymatic hydrolysis with alkaline protease alone), the total reducing sugar, total amino acid, and total volatile component contents of the low-fat flavored peanuts in Example 2 were significantly increased. This shows that the use of both sucrase and alkaline protease for enzymatic hydrolysis can significantly increase the contents of both free amino acids and reducing sugars, two flavor precursors, thereby contributing to the production of a large number of flavor components.

[0098] The total reducing sugar, total amino acid and total volatile component contents in the low-fat flavored peanuts of Example 3 were significantly higher than those in the non-defatted enzymatically hydrolyzed group of Comparative Example 1 and the defatted non-enzymatically hydrolyzed group of Comparative Example 2, but lower than that in Example 2. In addition, the total volatile component content in the low-fat flavored peanuts of Example 3 was lower than that in Example 2. This indicates that moderate restrictive pressure defatting treatment can enhance the release of flavor substances, but when the defatting pressure reaches a certain limit, its flavor-promoting effect may tend to stabilize.

[0099] The total reducing sugar, total amino acid, and total volatile component contents of the low-fat flavored peanuts of Example 4 were significantly higher than those of the non-defatted enzymatically hydrolyzed group of Comparative Example 1 and the defatted, non-enzymatically hydrolyzed group of Comparative Example 2, but lower than those of Example 2. Furthermore, the total volatile component content of the low-fat flavored peanuts of Example 4 was higher than that of the group of Example 1. This demonstrates that dry enzymatic hydrolysis of defatted peanut kernels using alkaline protease and sucrase can produce a peanut product that complies with the national standard "SB / T 10614-2011 Cooked Peanuts (Kernels)" and has excellent flavor, even at lower heat treatment temperatures and shorter heat treatment times (compared to direct heating of the peanuts, as in Comparative Example 9). Furthermore, this method preserves heat-sensitive nutrients in the peanuts, avoids severe protein damage, and eliminates the production of hazardous ingredients, thereby enhancing the safety and nutritional value of the product.

[0100] In addition, defatting treatment at a pressing pressure of 10 to 60 MPa can promote the enzymatic hydrolysis of peanut raw materials and increase the release of flavor precursors. However, when the defatting pressure reaches a certain limit (30 MPa), the enzymatic hydrolysis effect also tends to be optimal.

[0101] The total reducing sugar, total amino acid, and total volatile component contents of the flavored peanuts in Comparative Example 3 were significantly lower than those in Examples 1-5. This demonstrates that the order of defatting and enzymatic hydrolysis significantly influences peanut flavor. Defatting followed by enzymatic hydrolysis not only improves the degradation of protein and other components but also releases more flavor precursors, thereby enhancing the flavor quality of the final product.

[0102] Compared with Example 2, the time for frying the seeds in Comparative Example 6 is longer than that in Example 2. Therefore, an excessively long heat treatment time is not conducive to the further generation of flavor components.

[0103] Compared to Example 2, the flavored peanuts in Comparative Examples 7 and 8 showed significantly lower levels of total reducing sugars, total amino acids, and total volatile components, demonstrating that the addition of enzymes significantly promotes the formation of flavor precursors. In Example 2, the addition of a phosphate-citrate buffer containing a specific enzyme preparation effectively catalyzed the decomposition of polysaccharides and proteins in the peanut matrix, releasing more reducing sugars and free amino acids, providing ample substrate for the subsequent Maillard reaction. However, in Comparative Examples 7 and 8, enzymes were not added under the same buffer system, resulting in a lack of enzymatic hydrolysis, leading to insufficient accumulation of precursors and inhibiting the formation of flavor compounds. This result further demonstrates the critical role of enzymatic pretreatment in flavor enhancement.

[0104] Compared with Example 2, Comparative Example 9 was neither defatted nor enzymatically hydrolyzed. The total reducing sugar, total amino acid, and total volatile component contents in the flavored peanuts of Comparative Example 9 were significantly lower than those of Example 2, indicating that the defatting and enzymatic hydrolysis of the present invention can release more flavor precursors, thereby improving the flavor quality of the final product.

[0105] The types and contents of various volatile substances are shown in Table 2.

[0106] Table 2 Types and contents of various volatile substances in different groups

[0107]

[0108]

[0109] Figure 4 The results in Table 2 indicate that the overall content of flavor volatiles in the samples significantly increased after complex enzyme treatment, and the variety of compounds became richer. Enzymatic hydrolysis helps release bound flavor precursors from the matrix. For example, polysaccharide hydrolysis produces reducing sugars, and protein degradation releases amino acids and sulfur-containing compounds, providing more substrates for flavor-forming reactions such as the Maillard reaction and lipid oxidation. The resulting characteristic flavor components, such as aldehydes, ketones, alcohols, pyrazines, and furans, not only increased in number but also became more diverse in their structural types. Overall flavor complexity and intensity were significantly enhanced, demonstrating that complex enzyme pretreatment positively impacts flavor quality.

[0110] Test Example 2

[0111] 2.1 Effect of different material-liquid ratios on dry decomposition treatment

[0112] 2.1.1 A method for preparing defatted peanut kernels after enzymatic hydrolysis, comprising the following steps:

[0113] High-quality, mature, and non-deteriorated peanut kernels were selected as raw material and pressed at 30 MPa in a hydraulic press at room temperature for 1 hour. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 15g of sucrase was dissolved in 1500mL of phosphate-citrate buffer at a pH of 4.5. Subsequently, 3000g, 1500g, 750g, and 500g of defatted peanut raw material (i.e., material-liquid ratios of 1:0.5, 1:1, 1:2, and 1:3, respectively) were soaked in 1500mL of enzymatic hydrolysis solution. After soaking at 55°C for 30 minutes, the enzymatic hydrolysis solution was removed and the peanuts were enzymatically hydrolyzed at 55°C for 3 hours to obtain the defatted peanut kernels. The defatted, unenzymatically hydrolyzed peanut raw material consisted of high-quality, mature, non-deteriorated peanut kernels. The raw material was pressed at 30 MPa in a hydraulic press at room temperature for 1 hour. The defatted, unenzymatically hydrolyzed peanut raw material was collected.

[0114] The total reducing sugar content in the defatted peanut kernels after enzymatic hydrolysis prepared at different material-liquid ratios was tested according to the experimental example 1. The results are shown in Table 3.

[0115] Table 3 Comparison of total reducing sugar content in defatted peanut kernels after enzymatic hydrolysis prepared at different material-liquid ratios

[0116]

[0117] The results in Table 3 show that, compared to the total reducing sugar content in the raw material before enzymatic hydrolysis, a material-to-liquid ratio of 1:0.5 to 1:3 significantly increases the total reducing sugar content in the peanut kernels after enzymatic hydrolysis, while ensuring dry enzymatic hydrolysis. This results in a favorable enzymatic hydrolysis effect, thereby increasing the content of flavor precursors in the peanut kernels. Therefore, considering factors such as enzymatic hydrolysis effect and energy consumption, the material-to-liquid ratio of defatted peanut raw material to protease hydrolysis solution is 1:0.5 to 1:3.

[0118] 2.1.2 A method for preparing defatted peanut kernels after enzymatic hydrolysis, comprising the following steps:

[0119] High-quality, mature, and non-deteriorated peanut kernels were selected as raw material and pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 7.5 g of alkaline protease was dissolved in 1500 mL of phosphate-citrate buffer at pH 7. Subsequently, 3000 g, 1500 g, 750 g, and 500 g of defatted peanuts (i.e., material-liquid ratios of 1:0.5, 1:1, 1:2, and 1:3, respectively) were soaked in 1500 mL of the enzymatic hydrolysis solution. After soaking at 55°C for 10 minutes, the enzymatic hydrolysis solution was removed and the peanuts were hydrolyzed at 55°C for 1 hour to obtain the enzymatically hydrolyzed defatted peanut kernels. The defatted, unhydrolyzed peanut raw material consisted of high-quality, mature, non-deteriorated peanut kernels pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The defatted, unhydrolyzed peanut raw material was collected.

[0120] The total amino acid content in the defatted peanut kernels after enzymatic hydrolysis prepared at different material-liquid ratios was tested according to the experimental example 1. The results are shown in Table 4.

[0121] The results in Table 4 show that, compared to the total amino acid content in the raw material before enzymatic hydrolysis, a material-to-liquid ratio of 1:0.5 to 1:3 significantly increases the total amino acid content in the peanut kernel after enzymatic hydrolysis, while ensuring dry enzymatic hydrolysis. This results in a favorable enzymatic hydrolysis effect, thereby increasing the content of flavor precursors in the peanut kernel. Therefore, considering factors such as enzymatic hydrolysis effect and energy consumption, the material-to-liquid ratio of defatted peanut raw material to carbohydrate enzymatic hydrolysate is 1:0.5 to 1:3.

[0122] Table 4 Comparison of total amino acid content in defatted peanut kernels after enzymatic hydrolysis prepared at different material-liquid ratios

[0123]

[0124] 2.2 Effect of enzyme dosage on dry enzymatic hydrolysis treatment

[0125] 2.2.1 A method for preparing defatted peanut kernels after enzymatic hydrolysis, comprising the following steps:

[0126] High-quality, mature, non-deteriorated and non-mildewed peanut kernels were selected as raw materials, and were pressed at 30 MPa by a hydraulic oil press, the pressing temperature was room temperature, and the pressing time was 1 hour. The defatted peanut raw materials were collected to obtain enzymatic hydrolysis raw materials. 0.0g, 0.25g, 0.50g, 2.5g and 5.0g (i.e., the enzyme addition amount was 0wt%, 0.05wt%, 0.1wt%, 0.5wt% and 1wt%) of sucrase were respectively dissolved in 500mL of phosphate-citrate buffer with a pH of 4.5, and then 500g (i.e., the material-liquid ratio was 1:1) of defatted peanut raw materials were respectively soaked in 500mL of enzymatic hydrolysis solution, soaked at 55°C for 30min, the enzymatic hydrolysis solution was poured out, and enzymatic hydrolysis was carried out at 55°C for 3h to obtain enzymatically hydrolyzed defatted peanut kernels. Among them, the defatted non-enzymatically treated peanut raw materials, that is, high-quality, mature, non-deteriorated and non-mildewed peanut kernels are selected as raw materials, and are pressed by a hydraulic oil press at 30MPa, the pressing temperature is room temperature, and the pressing time is 1h, and the defatted non-enzymatically treated peanut raw materials are collected.

[0127] The total reducing sugar content in the defatted peanut kernels after enzymatic hydrolysis prepared with different enzyme dosages was tested according to Experimental Example 1. The results are shown in Table 5.

[0128] Table 5 Effect of different enzyme dosages on the total reducing sugar content in defatted peanut kernels after enzymatic hydrolysis

[0129]

[0130]

[0131] The results in Table 5 show that compared to the total reducing sugar content in the raw material before enzymatic hydrolysis, the total reducing sugar content in the peanut kernels after enzymatic hydrolysis increased significantly when the sucrase dosage accounted for 0.05-1 wt% of the hydrolysis solution, resulting in a good enzymatic hydrolysis effect and an increase in the content of flavor precursors in the peanut kernels. Therefore, considering factors such as enzymatic hydrolysis effect and cost, the sucrase dosage should be 0.05-1 wt% of the hydrolysis solution.

[0132] 2.2.2 A method for preparing defatted peanut kernels after enzymatic hydrolysis, comprising the following steps:

[0133] High-quality, mature, non-deteriorated, and non-mildewed peanut kernels were selected as raw materials, and were pressed at 30 MPa by a hydraulic oil press, at room temperature, and for 1 hour. The defatted peanut raw materials were collected to obtain enzymatic hydrolysis raw materials. 0.0 g, 0.75 g, 1.50 g, 7.5 g, and 15.0 g (i.e., enzyme addition amounts of 0 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, and 1 wt%) of alkaline protease were dissolved in 1500 mL of phosphate-citrate buffer at pH 7, and then 500 g (i.e., a material-liquid ratio of 1:3) of defatted peanut raw materials were soaked in 1500 mL of enzymatic hydrolysis solution, soaked at 55° C. for 30 minutes, and then the enzymatic hydrolysis solution was poured out and enzymatic hydrolysis was performed at 55° C. for 3 hours to obtain enzymatically hydrolyzed defatted peanut kernels. Among them, the defatted non-enzymatically treated peanut raw materials, that is, high-quality, mature, non-deteriorated and non-mildewed peanut kernels are selected as raw materials, and are pressed by a hydraulic oil press at 30MPa, the pressing temperature is room temperature, and the pressing time is 1h, and the defatted non-enzymatically treated peanut raw materials are collected.

[0134] The total amino acid content in the defatted peanut kernels after enzymatic hydrolysis prepared with different enzyme dosages was tested according to Experimental Example 1. The results are shown in Table 6.

[0135] Table 6 Effect of different alkaline protease dosages on the total amino acid content in defatted peanut kernels after enzymatic hydrolysis

[0136] Protease enzyme dosage Total amino acid content (mg / 100g) Defatted non-enzymatically processed peanut raw materials 495.36±53.96 0wt% (0.0g) 561.85±55.72 0.05wt% (0.75g) 1249.19±134.93 0.1wt% (1.5g) 2929.03±129.42 0.5wt% (7.5g) 4591.81±124.70

[0137] The results in Table 6 show that when alkaline protease is used at a level of 0.05-1 wt% of the hydrolyzed solution (i.e., using protease without carbohydrase), the total amino acid content in the peanut kernels after enzymatic hydrolysis is significantly increased compared to the total amino acid content of the raw material before enzymatic hydrolysis. This results in a good enzymatic hydrolysis effect and increases the content of flavor precursors in the peanut kernels. Therefore, considering factors such as enzymatic hydrolysis effect and cost, the protease level should be 0.05-1 wt% of the raw material weight.

[0138] 2.3 Effect of soaking time on dry enzymatic hydrolysis treatment

[0139] 2.3.1 A method for preparing defatted peanut kernels after enzymatic hydrolysis, comprising the following steps:

[0140] High-quality, mature, and undamaged peanut kernels were selected as raw material and pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 7.5 g of alkaline protease was dissolved in 1500 mL of phosphate-citrate buffer (pH 7). Subsequently, 500 g (i.e., a material-liquid ratio of 1:3) of defatted peanuts were immersed in 1500 mL of the enzymatic hydrolysis solution at 55°C for 5, 10, 20, 30, and 40 minutes, respectively. The enzymatic hydrolysis solution was then removed and the peanuts were hydrolyzed at 55°C for 3 hours to obtain the enzymatically hydrolyzed defatted peanut kernels. The defatted, unhydrolyzed peanut raw material consisted of high-quality, mature, undamaged, and unmolded peanut kernels. The raw material was pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The unhydrolyzed, defatted peanut raw material was collected.

[0141] The total amino acid content in the defatted peanut kernels after enzymatic hydrolysis prepared at different soaking times was tested according to the experimental example 1. The results are shown in Table 7.

[0142] Table 7 Effect of different soaking times on the total amino acid content of defatted peanut kernels after enzymatic hydrolysis

[0143] Protease soaking time Total amino acid content (mg / 100g) Defatted non-enzymatically processed peanut raw materials 495.36±53.96 5min 4024.90±34.64 10min 4085.19±15.24 20min 4130.59±59.41 30min 4212.93±60.66 40min 4081.49±52.45

[0144] The results in Table 7 show that compared to the total amino acid content of the raw material before enzymatic hydrolysis (804.38 ± 108.97 mg / 100 g), the total amino acid content of the peanut kernels after enzymatic hydrolysis increased significantly when the protease hydrolyzate was soaked for 5 to 40 minutes, resulting in a good enzymatic hydrolysis effect and an increase in the content of flavor precursors in the peanut kernels. Therefore, considering factors such as enzymatic hydrolysis effect, cost, and process time, the optimal soaking time for the protease hydrolyzate is 5 to 40 minutes.

[0145] 2.3.2 A method for preparing defatted peanut kernels after enzymatic hydrolysis, comprising the following steps:

[0146] High-quality, mature, and undamaged peanut kernels were selected as raw material and pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 5g of invertase was dissolved in 500mL of phosphate-citrate buffer (pH 4.5). Subsequently, 500g (i.e., a 1:1 material-liquid ratio) of defatted peanuts were immersed in 500mL of the enzymatic hydrolysis solution at 55°C for 5, 10, 20, 30, and 40 minutes, respectively. The enzymatic hydrolysis solution was then removed and the peanuts were hydrolyzed at 55°C for 3 hours to obtain the enzymatically hydrolyzed defatted peanut kernels. The defatted, unhydrolyzed peanut raw material consisted of high-quality, mature, undamaged, and unmolded peanut kernels. The raw material was pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The unhydrolyzed, defatted peanut raw material was collected.

[0147] The total reducing sugar content in the defatted peanut kernels after enzymatic hydrolysis prepared at different soaking times was tested according to the experimental example 1. The results are shown in Table 8.

[0148] Table 8 Comparison of total reducing sugar content in defatted peanut kernels after enzymatic hydrolysis prepared at different soaking times

[0149] Sucrase soaking time Total reducing sugar content (mg / 100g) Defatted non-enzymatically processed peanut raw materials 0 5min 4611.98±42.59 10min 4725.83±57.23 20min 4251.82±75.60 30min 4344.73±75.65 40min 4327.72±58.75

[0150] The results in Table 8 show that compared to the total reducing sugar content of the raw material before enzymatic hydrolysis (0 mg / 100 g), the total reducing sugar content in the defatted peanut kernels after enzymatic hydrolysis increased significantly when the carbohydrase soaking time was 5 to 40 minutes, resulting in a good enzymatic hydrolysis effect and an increase in the content of flavor precursors in the peanut kernels. Therefore, considering factors such as enzymatic hydrolysis effect, cost, and process time, the carbohydrase soaking time is 5 to 40 minutes.

[0151] 2.4 Effect of enzymatic hydrolysis time on dry enzymatic hydrolysis treatment effect

[0152] 2.4.1 A method for preparing defatted peanut kernels after enzymatic hydrolysis, comprising the following steps:

[0153] High-quality, mature, and undamaged peanut kernels were selected as raw material and pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 7.5 g of alkaline protease was dissolved in 1500 mL of phosphate-citrate buffer at pH 7. Subsequently, 500 g (i.e., a material-liquid ratio of 1:3) of defatted peanuts were soaked in 1500 mL of the enzymatic hydrolysis solution at 55°C for 30 minutes. The solution was then removed and the peanuts were enzymatically hydrolyzed at 55°C for 0.5, 1, 2, 3, and 4 hours, respectively, to obtain the enzymatically hydrolyzed defatted peanut kernels. The defatted, unenzymatically hydrolyzed peanut raw material consisted of high-quality, mature, undamaged, and unmolded peanut kernels. The defatted, unenzymatically hydrolyzed peanut raw material consisted of high-quality, mature, undamaged, and unmolded peanut kernels. The peanuts were pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The unenzymatically hydrolyzed peanut raw material was collected.

[0154] The total amino acid content in the defatted peanut kernels after enzymatic hydrolysis prepared at different enzymatic hydrolysis times was tested according to the experimental example 1. The results are shown in Table 9.

[0155] Table 9 Comparison of total amino acid content in defatted peanut kernels after enzymolysis prepared at different enzymolysis times

[0156] Protease enzymatic digestion time Total amino acid content (mg / 100g) Defatted non-enzymatically processed peanut raw materials 495.36±53.96 0.5h 4555.39±31.06 1h 4509.01±66.48 2h 4542.33±53.18 3h 4960.82±11.38 4h 4238.80±92.82

[0157] The results in Table 9 show that compared to the total reducing sugar content of the raw material before enzymatic hydrolysis (0 mg / 100 g), the total amino acid content in the peanut kernels after enzymatic hydrolysis increased significantly when the protease hydrolysis time was 0.5 to 4 hours, achieving a good enzymatic hydrolysis effect and increasing the content of flavor precursors in the peanut kernels. Therefore, considering factors such as enzymatic hydrolysis effect, energy consumption, and process time, the optimal enzymatic hydrolysis time for protease is 0.5 to 4 hours.

[0158] 2.4.2 A method for preparing defatted peanut kernels after enzymatic hydrolysis, comprising the following steps:

[0159] High-quality, mature, and undamaged peanut kernels were selected as raw material and pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 0.5 g of sucrase was dissolved in 500 mL of phosphate-citrate buffer (pH 4.5). Subsequently, 500 g (i.e., a 1:1 material-liquid ratio) of defatted peanuts were immersed in 500 mL of the enzymatic hydrolysis solution at 55°C for 10 minutes. The solution was then removed and the peanuts were enzymatically hydrolyzed at 55°C for 0.5, 1, 1.5, and 2 hours, yielding the enzymatically hydrolyzed defatted peanut kernels. The defatted, unenzymatically hydrolyzed peanut raw material consisted of high-quality, mature, undamaged, and unmolded peanut kernels. The raw material was pressed at 30 MPa (room temperature) for 1 hour using a hydraulic press. The unenzymatically hydrolyzed peanut raw material was collected.

[0160] The total reducing sugar content in the defatted peanut kernels after enzymatic hydrolysis prepared at different enzymatic hydrolysis times was tested according to Experimental Example 1. The results are shown in Table 10.

[0161] Table 10 Comparison of total reducing sugar content in defatted peanut kernels after enzymatic hydrolysis prepared at different enzymatic hydrolysis times

[0162] Carbohydrate enzymatic hydrolysis time Total reducing sugar content (mg / 100g) Defatted non-enzymatically processed peanut raw materials 0 0.5h 4143.46±6.40 1h 4437.11±212.45 1.5h 3767.86±27.15 2h 3701.87±77.71

[0163] The results in Table 10 show that compared to the total reducing sugar content of the raw material before enzymatic hydrolysis (0 mg / 100 g), the total reducing sugar content in the defatted peanut kernels after enzymatic hydrolysis increased significantly when the sucrase hydrolysis time was 0.5 to 2 hours, resulting in a good enzymatic hydrolysis effect and increasing the content of flavor precursors in the peanut kernels. Therefore, considering factors such as enzymatic hydrolysis effect, cost, and process time, the optimal sucrase hydrolysis time is 0.5 to 2 hours.

[0164] 2.5 Effect of different degreasing pressure on aroma production

[0165] A method for preparing flavored peanuts, comprising the following steps:

[0166] 500g of high-quality, mature, and undeteriorated peanut kernels were selected as the raw material and pressed using a hydraulic press at 0, 10, 20, 30, 40, 50, or 60 MPa at room temperature for 1 hour. The defatted peanuts were collected to obtain the enzymatic hydrolysis raw material. 1.5g of sucrase and 7.5g of alkaline protease were dissolved in 1500mL of phosphate-citrate buffer (pH 6). The defatted peanuts were then soaked in 1500mL of the enzymatic hydrolysis solution at 55°C for 30 minutes. The solution was then removed and enzymatic hydrolysis was continued at 55°C for 3 hours to obtain the defatted peanut kernels. The defatted peanut kernels were then oven-dried at 40°C for 10 hours and then roasted in a seed roaster at 160°C for 15 minutes to produce the flavored peanuts.

[0167] The total reducing sugar content and total amino acid content in the flavored peanuts prepared at different defatting pressures were tested according to part 1 of Experimental Example. The results are shown in Table 11.

[0168] Table 11 Effects of different defatting pressures on the total reducing sugar content and total amino acid content in flavored peanuts

[0169] Degreasing pressure Total amino acid content (mg / 100g) Total reducing sugar content (mg / 100g) 0MPa 804.38±108.97 3636.58±75.74 10PMa 3023.49±27.17 4193.35±45.23 20PMa 3041.81±119.08 4045.10±45.66 30PMa 4591.80±336.83 4829.92±216.25 40PMa 4470.91±43.68 4746.97±190.63 50PMa 5268.64±262.24 5680.04±72.45 60PMa 4160.63±234.98 5164.61±81.95

[0170] The results in Table 11 show that under the appropriate enzymatic hydrolysis conditions (pH, temperature, etc.) of sucrase and alkaline protease, the enzymatic hydrolysis effects of peanut kernels are different after different defatting pressures. Compared with the peanut raw material without pressing, that is, 0 MPa, the enzymatic hydrolysis effect of the peanut kernels after pressing and defatting is better.

[0171] 2.6 Effects of different heat treatment temperatures and times on aroma production

[0172] 2.6.1 A method for preparing flavored peanuts, comprising the following steps:

[0173] 500g of high-quality, mature, and free of deterioration or mold were selected as the raw material and pressed using a hydraulic press at 30MPa for 1 hour at room temperature. The defatted peanuts were collected to obtain the enzymatic hydrolysis material. 1.5g of sucrase and 7.5g of alkaline protease were dissolved in 1500mL of phosphate-citrate buffer (pH 6). The defatted peanuts were then soaked in 1500mL of the enzymatic hydrolysis solution at 55°C for 30 minutes. The solution was then removed and enzymatic hydrolysis was continued at 55°C for 3 hours to obtain the defatted peanut kernels. The defatted peanut kernels were then oven-dried at 40°C for 10 hours. The dried peanut kernels were then roasted in a seed roaster at 130, 140, 150, 160, 170, and 180°C for 20 minutes, respectively, to produce the flavored peanuts.

[0174] The total reducing sugar content and total amino acid content in the flavored peanuts prepared at different heat treatment temperatures were tested according to the first part of Experimental Example. The results are shown in Table 12.

[0175] Table 12 Effects of different heat treatment temperatures on the total reducing sugar content and total amino acid content of flavored peanuts

[0176] Heat treatment temperature Total amino acid content (mg / 100g) Total reducing sugar content (mg / 100g) 130℃ 2625.18±27.39 1988.49±47.32 140℃ 2550.26±100.26 1767.76±11.99 150℃ 2583.66±64.23 1271.80±10.97 160℃ 1914.02±17.43 905.86±16.06 170℃ 2862.71±75.57 865.50±54.53 180℃ 2394.47±61.30 442.45±53.90

[0177] The results in Table 12 show that when the heat treatment temperature is between 130℃ and 180℃, the total amino acid and reducing sugar content in the defatted flavored peanuts decreases with increasing treatment temperature, which can bring about a good heat treatment aroma effect, thereby ensuring the rich flavor of the peanuts.

[0178] 2.6.2 A method for preparing flavored peanuts, comprising the following steps:

[0179] 500g of high-quality, mature, and free of deterioration or mold were selected as the raw material and pressed using a hydraulic press at 30MPa for 1 hour at room temperature. The defatted peanuts were collected and used as the enzymatic hydrolysis raw material. 1.5g of sucrase and 7.5g of alkaline protease were dissolved in 1500mL of phosphate-citrate buffer (pH 6). The defatted peanuts were then soaked in 1500mL of the enzymatic hydrolysis solution at 55°C for 30 minutes. The solution was then removed and enzymatic hydrolysis was continued at 55°C for 3 hours to obtain the defatted peanut kernels. The defatted peanut kernels were then oven-dried at 40°C for 10 hours and then roasted in a 160°C roaster for 10, 15, 20, 30, 40, 50, and 60 minutes, respectively, to produce the flavored peanuts.

[0180] The total reducing sugar content and total amino acid content in the flavored peanuts prepared with different heat treatment times were tested according to the first part of Experimental Example. The results are shown in Table 13.

[0181] Table 13 Effects of different heat treatment times on the total reducing sugar content and total amino acid content of flavored peanuts

[0182] Heat treatment time Total amino acid content (mg / 100g) Total reducing sugar content (mg / 100g) 10min 2650.18±22.72 1629.32±37.41 15min 1756.36±48.36 900.77±21.56 20min 1964.24±53.29 905.86±16.06 30min 2117.62±109.76 879.27±43.69 40min 2264.43±13.05 526.55±61.82 50min 2194.43±70.60 813.73±44.36 60min 2062.72±81.21 846.55±30.65

[0183] The results in Table 13 show that when the heat treatment time ranged from 10 to 50 minutes, the total amino acid and reducing sugar contents of the defatted flavored peanuts exhibited significant changes, both contributing to a favorable heat-treatment aroma-producing effect and ensuring the rich, aromatic flavor of the defatted peanuts. During the roasting process, the reducing sugar content of the samples decreased initially and then increased with increasing roasting time, ranging from 10 to 50 minutes. This initial decrease in reducing sugars is primarily attributed to their role as a primary substrate in the Maillard reaction, which rapidly reacts with amino acids during the initial heating phase to produce a series of browning intermediates and flavor precursors. Furthermore, at high temperatures, reducing sugars can undergo non-enzymatic reactions such as carbonyl interconversion and cleavage, further depleting their content. With increasing roasting time, the tissue structure gradually breaks down, cell walls loosen, and some bound or structural sugars are gradually released into the system, leading to a rebound in the detectable reducing sugar content. This trend demonstrates that, under complex thermal processing conditions, the dynamic changes in reducing sugars are not only influenced by reaction consumption but also by the synergistic effects of multiple factors, including substrate release and pyrolytic conversion. Therefore, considering the factors such as the aroma-generating effect of heat treatment, energy consumption, and process time, the heat treatment time is 10 to 50 minutes.

[0184] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing low-fat flavored peanuts, characterized in that: The following steps are involved: Pressing and defatting the peanut kernels to obtain defatted peanuts; Dissolving sucrase and alkaline protease in a buffer solution to obtain an enzymatic hydrolyzate having a pH of 3 to 9; soaking the defatted peanuts in an enzymatic hydrolysis solution, pouring out the enzymatic hydrolysis solution, and performing enzymatic hydrolysis to obtain enzymatically hydrolyzed defatted peanuts; The defatted peanuts after enzymatic hydrolysis are dried and the seeds are roasted to obtain low-fat flavored peanuts.

2. The preparation method according to claim 1, characterized in that The pressing pressure is 10-60 MPa, and the pressing time is 0.5-1.5 h.

3. The preparation method according to claim 1, characterized in that The mass ratio of the sucrase to the alkaline protease is 1:(4-6); the mass volume ratio of the sucrase to the buffer solution is (0.05-1) g:100 mL; and the mass volume ratio of the alkaline protease to the buffer solution is (0.05-1) g:100 mL.

4. The preparation method according to claim 1, characterized in that The mass volume ratio of the defatted peanuts to the enzymatic hydrolysis solution is 1g:(1-3)mL.

5. The preparation method according to claim 1, characterized in that The soaking temperature is 45° C. to 60° C., and the soaking time is 5 to 40 minutes.

6. The preparation method according to claim 1, characterized in that The temperature of the enzymatic hydrolysis is 45° C. to 60° C., and the time of the enzymatic hydrolysis is 0.5 to 4 hours.

7. The preparation method according to claim 1, characterized in that The temperature for frying the seeds is 120° C. to 160° C., and the time for frying the seeds is 10 to 50 minutes.

8. The preparation method according to claim 1, characterized in that Oven drying and blast drying are adopted, the drying temperature is 30-55° C., and the drying time is 8-12 hours.

9. Low-fat flavored peanuts prepared by the preparation method according to any one of claims 1 to 7.

10. The low-fat flavored peanuts according to claim 8, characterized in that: The low-fat flavored peanuts have high contents of total reducing sugars, total amino acids and total volatile components.

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