A method for improving the quality of aleurone layer flour and aleurone-rich wheat flour using cold plasma technology

Abstract

This invention discloses a method for improving the quality of aleurone layer and aleurone-rich wheat flour using cold plasma technology. The aleurone layer powder preparation method includes wheat cleaning; preparing PAW (pasteurized wheat bran) using a cold plasma generator; activating water-soaked wheat with cold plasma; dehulling the soaked wheat grains using a wheat dehulling machine, collecting the tissue from the dehulling process to obtain aleurone layer powder, and collecting the grains after the aleurone layer has been removed; processing the aleurone layer powder in a dielectric barrier discharge (DBD) type cold plasma treatment device; and preparing aleurone-rich wheat flour by adding the aleurone layer powder to wheat flour at a dosage of 5% to 20%. This invention improves the complete separation of the bran and aleurone layer through PAW soaking, increases the purity of aleurone layer powder and flour, reduces the load of subsequent cleaning, sieving, and air classification, reduces reliance on high-energy-consuming equipment such as cleaning machines, thereby reducing milling energy consumption and improving production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a method for preparing aleurone layer powder and aleurone-rich wheat flour, and particularly to a method for improving the purity of aleurone layer powder by activating water-moistened wheat with cold plasma. Background Technology

[0002] With the improvement of people's living standards, consumers are paying more and more attention to food safety. Wheat, as one of the most important grain crops in my country, occupies a pivotal position in the national diet. Its grain is mainly composed of three parts: bran, germ, and endosperm. Among them, the aleurone layer, as the innermost layer of the bran, is a key nutritional transition layer connecting the bran and the endosperm. Although it only accounts for 7% to 9% of the total mass of wheat grain, it concentrates about 60% to 70% of the micronutrients and functional active ingredients in the grain, including dietary fiber, high-quality plant protein, various minerals such as calcium, iron, and zinc, B vitamins, vitamin E, and phenolic compounds such as ferulic acid and phytosterols. These nutrients have clear physiological functions. Dietary fiber can effectively promote intestinal peristalsis, prevent and improve constipation, regulate postprandial blood sugar levels, and reduce sugar absorption. Ferulic acid and phytosterols can help regulate blood lipids and protect cardiovascular health. Long-term intake can effectively reduce the risk of cardiovascular disease. Therefore, the aleurone layer is also considered to be one of the most nutritious components in wheat grain. Aleurone layer powder prepared from aleurone layer as raw material, and aleurone-rich wheat flour made by blending aleurone layer powder with wheat flour, have higher nutritional value and health benefits than ordinary wheat flour. They can effectively reduce human cholesterol levels, regulate intestinal flora imbalance, and prevent chronic diseases. They have become a research hotspot and market demand growth point in the field of whole grain food processing in recent years.

[0003] Currently, aleurone layer flour and aleurone-rich wheat flour face challenges in processing, storage, and application, including difficulties in aleurone layer separation, low product purity, and insufficient flour cleanliness. On one hand, the aleurone layer easily becomes mixed with seed coat fibers and endosperm starch granules during separation, resulting in a higher content of seed coat fibers and endosperm powder in the resulting aleurone layer flour, insufficient aleurone layer cell enrichment, and lower product purity. On the other hand, broken bran powder and bran particles easily enter the endosperm powder stream, increasing the proportion of bran particles and ash content in the flour, and decreasing whiteness, thus affecting flour grade, processing quality, and the appearance of the final product.

[0004] Currently, both domestic and international methods for improving the quality of aleurone layer powder and aleurone-rich wheat flour mainly involve physical modification, chemical modification, and biological modification to enhance the nutritional components or stability of the aleurone layer powder. However, existing technologies cannot improve the purity of the aleurone layer, and production efficiency is low. For example, invention patent CN 112715834 B discloses a method for modifying wheat aleurone layer powder, finding that mixing wheat aleurone layer powder with a citric acid aqueous solution and then performing high-speed homogenization can effectively increase the content of soluble fiber without significantly affecting the gluten network after mixing with wheat flour. In his article "The Influence of Lactobacillus plantarum Fermentation on Wheat Aleurone Layer Powder on Bread Quality," Geng Hao reported on the fermentation of wheat aleurone layer powder using Lactobacillus plantarum, finding that the optimal fermentation time was 22 h, the fermentation temperature was 38 ℃, and the inoculum concentration was 1.4 × 10⁻⁶. 7 CFU / g, under these conditions, the total polyphenol content increased significantly, and the phytic acid content decreased significantly after fermentation. Jin Cancan reported in the article "Stabilization Treatment of Wheat Aleurone Layer Powder and Its Effect on Steamed Bun Quality" that three methods were used to stabilize wheat aleurone layer powder: extrusion, superheated steam, and microwave irradiation. The results showed that all three methods effectively reduced the fatty acid value of wheat aleurone layer powder. Through comparative analysis of safety and nutritional indicators of the materials under the best treatment parameters, extrusion treatment showed the best stabilization effect. Tian Boyu reported in the article "Preparation of Stabilized Aleurone Layer Wheat Flour and its Processing Quality Improvement" that baking, microwave, ultrasonic, and ultraviolet treatments could all reduce the activity of lipase and lipoxygenase in the aleurone layer enriched components. The stabilized aleurone layer wheat flour obtained by microwave treatment was still edible after 168 days of storage.

[0005] The existing technology also has the following drawbacks: (1) Although chemical modification such as citric acid can increase the soluble fiber content, it is essentially a chemical grafting process, which is prone to introducing foreign chemical residues, which contradicts the current consumer demand for "clean label" and "natural and additive-free".

[0006] (2) Traditional physical methods, such as ultraviolet irradiation, have insufficient penetrating power and can only act on the surface of materials. They are ineffective against microorganisms inside the aleurone layer and in the gaps between particles. Furthermore, the unevenness of the sample surface will greatly reduce the inactivation efficiency. The difference in dielectric properties of microwave treatment leads to uneven energy distribution, which easily results in local heating while other areas are insufficient.

[0007] (3) Although extrusion can improve the taste, high temperature and high pressure will destroy heat-sensitive nutrients and accelerate the oxidation of aleurone layer lipids, further shortening the shelf life. In addition, the aleurone layer functional components are easily lost during the puffing process, and the maximum retention of nutrients cannot be achieved.

[0008] (4) In biomodification, microbial fermentation has a long cycle and complex process, making it difficult to adapt to industrial mass production. Furthermore, the fermentation process is prone to contamination by miscellaneous bacteria, affecting product stability. At the same time, the fermentation process will change the inherent flavor of the aleurone layer powder, reduce product palatability, have limited inhibitory effect on lipid oxidation, and require additional testing for the safety of fermentation products, which increases the production process.

[0009] Low-temperature plasma activated water (PAW) is an aqueous solution formed by treating water with low-temperature plasma. The current application of cold plasma activated water (PAW) technology in the food processing field is mainly for eliminating toxins or killing microorganisms. Summary of the Invention

[0010] To overcome the shortcomings and deficiencies of existing technologies, this invention provides a method for improving the quality of wheat flour with aleurone layers and aleurone-rich layers using cold plasma technology. Through the synergistic effect of "cold plasma activation of water-soaked wheat + secondary cold plasma treatment," it solves problems such as difficult cell separation, low purity, and poor nutrient utilization in the aleurone layer in existing technologies, achieving simultaneous improvement in product purity, nutritional quality, and processing characteristics. This invention is achieved through the following technical solution: A method for improving the quality of aleurone layer flour and aleurone-rich wheat flour using cold plasma technology includes the following steps: (1) Wheat cleaning: Remove impurities such as wheat straw, imperfect grains, discolored grains, and stones from wheat grains through screening, winnowing, and color sorting; (2) Preparation of cold plasma activated water: Using a cold plasma generator, ordinary water is activated by plasma to obtain cold plasma activated water (PAW), which is then sealed for later use; (3) Cold plasma activated water-moistening wheat: Select the appropriate amount of water and time for moistening wheat according to the hardness of wheat, put the wheat grains into a sealed container, add PAW and mix thoroughly; (4) Preparation of aleurone layer powder: The wheat grains that have been thawed in (3) are dehulled using a wheat dehulling machine. The tissues under the dehulling process are collected to obtain aleurone layer powder, and the grains after the aleurone layer has been removed are collected. (5) The aleurone layer powder is placed in the discharge chamber of the cold plasma (CP) treatment equipment for treatment and stored in a cool, dry place at room temperature to obtain the aleurone layer powder; (6) Preparation of wheat flour: The wheat grains after conditioning and peeling in (4) are milled into flour using a milling machine; (7) Preparation of aleurone-rich wheat flour: The aleurone-rich wheat flour is prepared by mixing the aleurone-rich flour prepared in (5) with the wheat flour prepared in (6) in a certain proportion. The ordinary water mentioned in step (2) is tap water or other water that has not undergone special treatment; The parameters of the cold plasma equipment for preparing PAW in step (2) are: the raw material gas is air, the preparation voltage is 20~50 kV, and the preparation time is 2~10 min; In step (3), the moisture content of soft wheat is adjusted to 13%~14%, and the moisture content of hard wheat (including medium-hardness wheat) is adjusted to 15%~18%, and the soaking time is 10~30 h; The wheat peeling machine used in step (4) is a flexible peeling machine or a milling / scraping machine, rice milling machine, etc. The peeling rate should be controlled at 5%~12%, and the dietary fiber content in the peeled tissue should be 30~40%, the pentosan content should be greater than 19%, and the protein content should be 15%~24%. If the above conditions are met, it is aleurone layer powder. The aleurone layer powder is then pulverized by ultra-fine grinding and passed through an 80-mesh sieve for later use. The cold plasma technology described in step (5) uses a dielectric barrier discharge (DBD) type cold plasma processing device, and the discharge method is a gas-liquid two-phase mixed discharge. The raw material gas for the cold plasma technology described in step (5) is air, with a power of 100~150 W, a discharge frequency of 20~30 kHz, a gas flow rate of 1~1.5 L / min, a discharge gap of 8~12 mm, a raw material layer thickness of 1~3 mm, and a processing time of 2~10 min. The amount of aleurone powder added in step (7) is 5% to 20%.

[0011] Compared with the prior art, the present invention has the following advantages and beneficial effects: Plasma-activated water (PAW) treatment can significantly improve the purity and peeling effect of aleurone layer powder and flour. This invention utilizes PAW for wheat rinsing. The active oxygen / nitrogen species in PAW can enter the interface between the wheat bran, aleurone layer, and endosperm along with the water, producing mild oxidation and limited chain scission on structural components such as the bran wax layer, cellulose, hemicellulose, arabinoxylan, and lignin. This loosens the cell wall structure of the bran and aleurone layer, weakening the binding force between the bran, aleurone layer, and endosperm cells. Simultaneously, PAW reduces the contact angle between rinsing water molecules and the wheat bran surface, increasing the wetting and migration speed of water in bran folds, ventral grooves, and microporous structures. Therefore, the bran is more easily and completely peeled off during the rinsing process, reducing the amount of bran fragments entering the endosperm powder stream and improving the purity of the subsequent wheat flour. Furthermore, PAW molecules facilitate the separation of the epidermis, pericarp, seed coat, nucellus, and endosperm tissue from the aleurone layer cells, thereby increasing the enrichment and purity of target cells in the aleurone layer powder. Unlike traditional processes that rely on purifiers to repeatedly separate bran, endosperm, and fine flour, this invention improves the complete separation of the bran and aleurone layers through front-end PAW (pasteurized wheat) conditioning, reducing bran particles and bran fragments from the source into the flour, increasing flour purity, reducing the load on subsequent purifying, sieving, and air-separating processes, reducing reliance on high-energy-consuming equipment such as purifiers, thereby reducing milling energy consumption and improving production efficiency.

[0012] (2) This invention uses plasma-activated water (PAW) instead of ordinary water for wheat rinsing. By improving the wettability of the rinsing water on the surface of wheat grains, it can significantly accelerate water migration and shorten rinsing time. After cold plasma treatment, the surface tension of the water decreases and the content of active oxygen / nitrogen species increases, which enhances the affinity between the rinsing water and the surface of the wheat cortex. This is manifested in a decrease in the contact angle of water droplets on the surface of wheat grains and an increase in the spreading area. The decrease in the contact angle indicates that PAW can quickly wet the ventral groove, cortex folds and surface micropores of wheat, reducing the mass transfer resistance of water entering the cortex and aleurone layer interface. At the same time, the active species in PAW can gently oxidize the cortex wax layer and cell wall components, making the tissue structure loose and further promoting the migration of water into the grain interior. Therefore, PAW rinsing significantly improves rinsing efficiency through the dual effects of "improving wettability + loosening cortex structure".

[0013] (3) This invention fully releases the inherent nutritional advantages of aleurone layer flour and aleurone-rich wheat flour through the synergistic effect of cold plasma activation and secondary cold plasma treatment. During the PAW (particulate air-wheat) moisturizing stage, active oxygen / nitrogen species enter the wheat bran and aleurone layer, producing a mild oxidizing effect on components such as cellulose, arabinoxylan, and lignin in the cell wall, making the cell wall structure of the aleurone layer loose and porous, and weakening the binding between active ingredients such as phenols, flavonoids, and polysaccharides and the cell wall matrix; the subsequent secondary cold plasma treatment can further affect the cell wall of the aleurone layer by utilizing high-energy electrons, ions, ozone, and free radicals, promoting the moderate depolymerization of insoluble dietary fiber and its conversion into soluble dietary fiber, while promoting the release of bound phenols and flavonoids and improving antioxidant activity. This forms a synergistic nutritional enhancement mechanism of loosening the PAW interior and enhancing the release of CP (polyphenolic compounds). Compared with single PAW wheat rinsing or ordinary water-rinsing combined with CP treatment, this invention can more fully release the dietary fiber, phenols, flavonoids and B vitamins and other active nutrients in the aleurone layer, and reduce the content of anti-nutritional factors such as phytic acid. Moreover, the non-thermal treatment process avoids the loss of heat-sensitive nutrients, thereby simultaneously improving the nutritional quality and bioavailability of aleurone layer flour and aleurone-rich wheat flour.

[0014] (4) The present invention adopts a combination of cold plasma activation of water-moistened wheat and cold plasma secondary treatment to produce a certain passivation effect on endogenous enzymes related to rancidity, such as lipase and lipoxygenase, thereby slowing down the generation of free fatty acids and lipid oxidation process during storage. Attached Figure Description

[0015] Figure 1 The fatty acid value changes of aleurone layer flour and aleurone-rich layer wheat flour were accelerated during storage experiments after treatment according to the present invention. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0017] Example 1 (PAW wheat conditioning + CP treatment) High-quality, mold-free hard wheat was selected. Large impurities such as straw, wheat ears, and stones, as well as some lighter and smaller impurities, were removed from the wheat grains through sieving and stone removal. Activated water was prepared using a cold plasma device for 10 minutes. This activated water was then added and mixed thoroughly, and the wheat was allowed to soak for 10 hours. After soaking, the wheat grains were processed using a dehulling machine in five passes. The dehulled sample was collected as the aleurone layer powder. A dielectric barrier discharge (DBD) type cold plasma treatment device was used, with a discharge power of 120 W, a discharge frequency of 25 kHz, air as the reaction gas, a gas flow rate of 1.2 L / min, and a discharge gap of 10 mm. The aleurone layer powder was placed in the discharge chamber, with a layer thickness controlled at 2 mm, and the aleurone layer powder treatment time was 5 minutes. After treatment, it was added to wheat flour at a dosage of 10% to produce aleurone-rich wheat flour. Accelerated storage tests were conducted on aleurone layer powder and aleurone-rich wheat flour. The prepared aleurone layer powder and aleurone-rich wheat flour were sealed in polyethylene bags and placed in a constant temperature and humidity test chamber at 40℃ and RH 70% for accelerated storage tests, with samples taken once a week.

[0018] Example 2 (PAW wheat rinsing + CP direct treatment, changing the amount of aleurone powder added) High-quality, mold-free hard wheat was selected. Large impurities such as straw, wheat ears, and stones, as well as some lighter and smaller impurities, were removed from the wheat grains through sieving and stone removal. Activated water was prepared using a cold plasma device for 10 minutes. This activated water was then added and mixed thoroughly, and the wheat was allowed to soak for 10 hours. After soaking, the wheat grains were processed using a dehulling machine in five passes. The dehulled sample was collected as the aleurone layer powder. A dielectric barrier discharge (DBD) type cold plasma treatment device was used, with a discharge power of 120 W, a discharge frequency of 25 kHz, air as the reaction gas, a gas flow rate of 1.2 L / min, and a discharge gap of 10 mm. The aleurone layer powder was placed in the discharge chamber, with a layer thickness controlled at 2 mm, and the aleurone layer powder treatment time was 5 minutes. After treatment, it was added to wheat flour at a dosage of 15% to produce aleurone-rich wheat flour. Accelerated storage tests were conducted on aleurone layer powder and aleurone-rich wheat flour. The prepared aleurone layer powder and aleurone-rich wheat flour were sealed in polyethylene bags and placed in a constant temperature and humidity test chamber at 40℃ and RH 70% for accelerated storage tests, with samples taken once a week.

[0019] Example 3 (PAW wheat conditioning + CP direct treatment, with changes to CP treatment time) High-quality, mold-free hard wheat was selected. Large impurities such as straw, wheat ears, and stones, as well as some lighter and smaller impurities, were removed from the wheat grains through sieving and stone removal. Activated water was prepared using a cold plasma device for 10 minutes. This activated water was then added and mixed thoroughly, and the wheat was allowed to soak for 10 hours. After soaking, the wheat grains were processed using a dehulling machine in five passes. The dehulled sample was collected as the aleurone layer powder. A dielectric barrier discharge (DBD) type cold plasma treatment device was used, with a discharge power of 120 W, a discharge frequency of 25 kHz, air as the reaction gas, a gas flow rate of 1.2 L / min, and a discharge gap of 10 mm. The aleurone layer powder was placed in the discharge chamber, with a layer thickness controlled at 2 mm, and the aleurone layer powder treatment time was 7 minutes. After treatment, it was added to wheat flour at a dosage of 10% to produce aleurone-rich wheat flour. Accelerated storage tests were conducted on aleurone layer powder and aleurone-rich wheat flour. The prepared aleurone layer powder and aleurone-rich wheat flour were sealed in polyethylene bags and placed in a constant temperature and humidity test chamber at 40℃ and RH 70% for accelerated storage tests, with samples taken once a week.

[0020] Example 4 (PAW wheat conditioning + CP direct treatment to change wheat hardness) High-quality, mold-free soft wheat was selected. Large impurities such as straw, wheat ears, and stones, as well as some lighter and smaller impurities, were removed from the wheat grains through sieving and stone removal processes. Activated water was prepared using a cold plasma device for 10 minutes. This activated water was then added and mixed thoroughly, and the wheat was allowed to soak for 8 hours. After soaking, the wheat grains were processed using a dehulling machine in five passes. The dehulled sample was collected as the aleurone layer powder. A dielectric barrier discharge (DBD) type cold plasma treatment device was used, with a discharge power of 120 W, a discharge frequency of 25 kHz, air as the reaction gas, a gas flow rate of 1.2 L / min, and a discharge gap of 10 mm. The aleurone layer powder was placed in the discharge chamber, with a layer thickness controlled at 2 mm, and the aleurone layer powder treatment time was 5 minutes. After treatment, it was added to wheat flour at a dosage of 10% to produce aleurone-rich wheat flour. Accelerated storage tests were conducted on aleurone layer powder and aleurone-rich wheat flour. The prepared aleurone layer powder and aleurone-rich wheat flour were sealed in polyethylene bags and placed in a constant temperature and humidity test chamber at 40℃ and RH 70% for accelerated storage tests, with samples taken once a week.

[0021] Comparative Example 1 (PAW only) High-quality, mold-free hard wheat was selected. Large impurities such as straw, wheat ears, and stones, as well as some light and small impurities, were removed from the wheat grains through sieving and stone removal. Activated water was prepared using cold plasma equipment for 10 minutes. The activated water was added according to the wheat hardness, mixed thoroughly, and the wheat was soaked for 10 hours. After soaking, the wheat grains were processed using a dehulling machine in five stages. The dehulled sample was collected as aleurone layer powder. After processing, the aleurone layer powder was added to the wheat flour at a rate of 10% to prepare aleurone-rich wheat flour. Accelerated storage tests were conducted on the aleurone layer powder and the aleurone-rich wheat flour. The prepared aleurone layer powder and the aleurone-rich wheat flour were sealed in polyethylene bags and placed in a constant temperature and humidity test chamber at 40℃ and 70% RH for accelerated storage, with samples taken weekly.

[0022] Comparative Example 2 (Regularly moistened wheat + CP direct treatment) High-quality, mold-free hard wheat was selected. Large impurities such as straw, wheat ears, and stones, as well as some lighter and smaller impurities, were removed from the wheat grains through sieving and stone removal. Ordinary water was added to the wheat grains, and the mixture was thoroughly mixed and allowed to soak for 18 hours. After soaking, the wheat grains were processed using a dehulling machine in five passes. The dehulled sample was collected as the aleurone layer powder. A dielectric barrier discharge (DBD) type cold plasma treatment device was used, with a discharge power of 120 W, a discharge frequency of 25 kHz, air as the reaction gas, a gas flow rate of 1.2 L / min, and a discharge gap of 10 mm. The aleurone layer powder was placed in the discharge chamber, with a layer thickness controlled at 2 mm, and the treatment time was 5 minutes. After treatment, the aleurone layer powder was added to the wheat flour at a rate of 10%, producing aleurone-rich wheat flour. Accelerated storage tests were conducted on the aleurone layer powder. The prepared aleurone layer powder was sealed in a polyethylene bag and placed in a constant temperature and humidity test chamber at 40℃ and RH 70% for accelerated storage tests, with samples taken once a week.

[0023] Comparative Example 3 (Regularly Moistened Wheat Only) High-quality, mold-free hard wheat was selected. Large impurities such as straw, wheat ears, and stones, as well as some lighter and smaller impurities, were removed from the wheat grains through sieving and stone removal processes. Ordinary water was added to the wheat grains, and the mixture was thoroughly mixed and allowed to soak for 10 hours. After soaking, the wheat grains were processed using a dehulling machine in five stages. The dehulled sample was collected as the aleurone layer powder. After processing, the aleurone layer powder was added to the wheat flour at a rate of 10% to prepare aleurone-rich wheat flour. Accelerated storage tests were conducted on both the aleurone layer powder and the aleurone-rich wheat flour. The prepared aleurone layer powder and the aleurone-rich wheat flour were sealed in polyethylene bags and placed in a constant temperature and humidity test chamber at 40℃ and 70% RH for accelerated storage, with samples taken weekly.

[0024] Example 2 (PAW wheat rinsing + CP direct treatment, changing the amount of aleurone powder added) The difference between Example 2 and Example 1 is that the amount of aleurone layer powder added to the aleurone layer wheat flour is 15%, while the rest is the same as in Example 1.

[0025] Example 3 (PAW wheat conditioning + CP direct treatment, with changes to CP treatment time) The difference between Example 3 and Example 1 is that the cold plasma is used to directly treat the aleurone layer powder for 7 minutes, while the rest of the process is the same as in Example 1.

[0026] Example 4 (PAW wheat conditioning + CP direct treatment to change wheat hardness) The difference between Example 3 and Example 1 is that the wheat grains used are soft wheat, while the rest of the implementation is the same as in Example 1.

[0027] Comparative Example 1 (PAW only) The difference between Comparative Example 1 and Example 1 is that only PAW was used for wheat grains during the rinsing process, without CP treatment; otherwise, the process was the same as in Example 1.

[0028] Comparative Example 2 (Regularly moistened wheat + CP direct treatment) The difference between Comparative Example 2 and Example 1 is that ordinary water was used to moisten the wheat, while the rest of the process was the same as in Example 1.

[0029] Comparative Example 3 (Regularly Moistened Wheat Only) The difference between Comparative Example 3 and Example 1 is that the wheat-nourishing solution used is ordinary water, while the rest of the implementation is the same as in Example 1.

[0030] Table 1. Chemical composition content of aleurone layer powder under different treatment conditions sample protein(%) Pentosan (%) Dietary fiber (%) Ash content (%) Phytic acid (mg / g) Fatty acid value (mg / 100g) Vitamin B (mg / g) Total phenols (mg GAE / g) Flavonoids (mg RE / g) Example 1 / 2 18.42±0.35 9.86±0.24 29.66±0.42 3.35±0.22 16.25±0.12 72.19±0.36 5.69±0.25 3.76±0.23 1.48±0.11 Example 3 18.67±0.49 10.12±0.31 29.63±0.56 3.58±0.14 12.41±0.31 65.24±0.84 6.21±0.31 3.84±0.31 1.54+0.28 Example 4 18.15±0.37 9.53±0.28 28.54±0.43 3.11±0.36 14.69±0.34 73.76±0.12 5.58±0.26 3.61±0.19 1.43±0.57 Comparative Example 1 17.84±0.33 8.71±0.19 29.97±0.41 3.61±0.17 22.31±0.14 102.25±0.87 5.41±0.11 3.32±0.16 1.28±0.34 Comparative Example 2 18.06±0.25 9.02±0.22 29.31±0.94 3.47±0.61 19.06±0.27 83.59±0.11 5.47±0.24 3.59±0.42 1.31±0.36 Comparative Example 3 17.63±0.38 8.26±0.17 29.21±0.63 3.65±0.01 31.58±0.54 111.63±0.59 5.36±0.14 3.11±0.16 1.21±0.13 Note: Since the processing conditions of the aleurone layer powder are the same in Example 2 and Example 1, the indicators of the aleurone layer powder in Example 2 will not be described again.

[0031] Table 2. Basic component content of aleurone-rich wheat flour under different treatment conditions sample Moisture (%) Ash content (%) Soluble dietary fiber (%) Alkyl resorcinol (mg / 100g) Fatty acid value (mg / 100g) Example 1 12.63±0.98 0.84±0.23 11.82±0.23 7.74±0.31 54.14±0.15 Example 2 12.99±0.54 0.97±0.36 13.66±0.45 13.62±0.33 56.34±0.42 Example 3 13.67±0.17 0.83±0.22 11.52±0.16 7.45±0.12 50.26±0.22 Example 4 13.27±0.51 0.81±0.27 10.17±0.61 6.96±0.44 55.74±0.67 Comparative Example 1 12.45±1.25 0.81±0.45 2.78±0.14 6.98±0.22 67.37±0.37 Comparative Example 2 13.49±1.58 0.82±0.41 9.63±0.55 7.14±0.58 56.11±0.61 Comparative Example 3 13.50±0.26 0.83±0.21 2.11±0.15 7.36±0.45 79.02±0.45 Table 3. Effects of different wheat-soaking methods and soaking times on aleurone layer powder and flour purity. sample Types of wheat water Wheat soaking time (h) Aleurone layer cell percentage (%) Starch content (%) of aleurone layer Flour ash content (%) Flour whiteness (L*) Percentage of wheat bran area in flour production (%) Example 1 PAW 10 84.52±1.17 18.61±0.51 0.47±0.04 90.36±0.31 0.38±0.04 Comparative Example 2 Ordinary water 18 71.59±1.46 23.19±0.67 0.55±0.02 88.17±0.36 0.71±0.06 Comparative Example 3 Ordinary water 10 64.67±1.55 30.41±0.49 0.63±0.03 85.64±0.42 1.18±0.08 Note: The unmarked examples and comparative examples use the same type of water and time as the above examples, so they will not be elaborated on further. The wheat varieties used in the above examples are all hard wheat.

[0032] The changes in fatty acid values ​​of aleurone layer powder and aleurone-rich wheat flour prepared according to the steps of Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3 during accelerated storage tests are shown in the figures. Figure 1 The chemical composition content of aleurone layer powder under different treatment conditions is shown in Table 1; the basic component content of aleurone-rich wheat flour under different treatment conditions is shown in Table 2; the effects of different wheat conditioning methods and conditioning times on the purity of aleurone layer powder and flour are shown in Table 3.

[0033] The main conclusions are as follows: (1) The moisture content of hard wheat should be adjusted to 15%~18% of the wheat mass. According to the moisture adjustment time of hard wheat measured during the rinsing period of Comparative Example 1 and Comparative Example 3, Comparative Example 1 reached the rinsing time in 8~12 h, and Comparative Example 3 reached the rinsing time in 16~24 h. It can be seen that the use of cold plasma to activate water can greatly shorten the rinsing time of wheat grains. In addition, as shown in Table (3), the proportion of aleurone layer cells after PAW rinsing is significantly increased, and the starch content in the aleurone layer powder is reduced. In Example 1, the proportion of aleurone layer cells was 84.52%, and the starch content was reduced to 18.61%, indicating that PAW treatment weakened the binding force between the aleurone layer and the seed coat and endosperm, making the aleurone layer easier to peel off completely and accumulate. In contrast, the proportion of aleurone layer cells in the aleurone layer powder obtained by ordinary water rinsing for 10 h was only 64.67%, and the starch content was as high as 30.41%, indicating that the water migration of conventional water rinsing was insufficient in the same time period, and the separation of the aleurone layer and the endosperm was not sufficient. Furthermore, PAW (pasteurized wheat) conditioning improved the purity of the subsequent flour. The flour obtained in Example 1 had an ash content reduced to 0.47%, a whiteness increased to 90.36, and a bran particle area ratio of only 0.38%, all superior to the ordinary water-conditioned wheat group. This indicates that PAW treatment promotes complete peeling of the bran layer, reduces bran fragments and aleurone layer debris entering the endosperm flour stream, and reduces the bran particle and ash content in the flour from the source. In particular, PAW conditioning for 8-10 hours can achieve or even surpass the purity improvement effect of ordinary water-conditioned wheat after 18 hours, demonstrating that this invention can improve the purity of the aleurone layer and the flour while shortening the conditioning time, reducing the load on subsequent cleaning, sieving, and air-classifying processes, and reducing reliance on high-energy-consuming equipment such as cleaning machines.

[0034] (2) This invention can significantly improve the nutritional quality of aleurone layer flour and aleurone-rich wheat flour. As shown in Tables 1 and 2, after treatment in Examples 1 and 3, the basic nutritional components such as starch, protein, dietary fiber, and ash in the aleurone layer flour changed little, indicating that the non-thermal treatment method does not significantly damage the basic nutritional structure. At the same time, the phytic acid content decreased from 31.58 mg / g in the untreated group to 16.25 mg / g in Example 1 and 12.41 mg / g in Example 3, and the contents of total phenols, flavonoids, B vitamins, and the free radical scavenging capacity of DPPH and ABTS were all improved. As shown in Table 3, the soluble dietary fiber content in aleurone-rich wheat flour increased from 2.11% in the untreated group to 11.82% in Example 1 and 13.66% in Example 2, indicating that the secondary treatment of PAW wheat and CP can promote the loosening of the cell wall structure of the aleurone layer, release bound active ingredients, and improve the water solubility and functional properties of dietary fiber.

[0035] (3) From Figure 1 As can be seen, cold plasma synergistic treatment has a long-lasting inhibitory effect on lipid oxidation, significantly improving the storage stability of the product. During the 6-week accelerated storage period, the fatty acid value of the aleurone layer powder in Comparative Example 3 rapidly increased from approximately 111 mg / 100g initially to approximately 140 mg / 100g after 6 weeks. In contrast, the fatty acid values ​​of Examples 1 and 3 remained at a low level throughout the process, still controlled below approximately 80 mg / 100g after 6 weeks. Similarly, the aleurone-rich wheat flour showed the same trend.

[0036] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for improving the powder quality of aleurone layers using cold plasma technology, characterized in that, Includes the following steps: (1) Wheat cleaning: screening and removing impurities from wheat grains; (2) Preparation of cold plasma activated water (PAW): Using a cold plasma generator, ordinary water is activated by plasma. The preparation voltage is 20~50 kV and the preparation time is 2~10 min. (3) Cold plasma activated water-moistening wheat: Select the appropriate amount of water and time to moisten wheat according to the hardness of wheat, put the wheat into a sealed container, add PAW and mix thoroughly; (4) Preparation of aleurone layer powder: The wheat grains that have been thawed in (3) are dehulled using a wheat dehulling machine. The tissues under the dehulling process are collected to obtain aleurone layer powder, and the grains after the aleurone layer has been removed are collected. (5) The abrasive powder layer is treated with cold plasma treatment equipment. The raw material gas is air, the power is 100~150 W, the discharge frequency is 20~30 kHz, the gas flow rate is 1~1.5 L / min, the discharge gap is 8~12 mm, and the raw material layer thickness is 1~3 mm.

2. The method according to claim 1, characterized in that, When the wheat is soft, the moisture content should be adjusted to 13%-14%. When the wheat is medium-hard or hard, the moisture content should be adjusted to 15%-18%. The soaking time should be 10-30 hours.

3. The method according to claim 1, characterized in that, The wheat peeling machine is a flexible peeling machine, a milling / scraping machine, or a rice milling machine. The peeling rate is controlled at 5% to 12%, and the dietary fiber content in the peeled tissue is 30% to 41%, the pentosan content is greater than 19%, and the protein content is 15% to 24%. If the above conditions are met, it is aleurone layer powder. The aleurone layer powder is then pulverized by ultra-fine grinding and passed through an 80-mesh sieve for later use.

4. The method according to claim 1, characterized in that, The cold plasma equipment used is a dielectric barrier discharge (DBD) type, and the discharge mode is a gas-liquid two-phase mixed discharge.

5. The method according to claim 1, characterized in that, The cold plasma equipment used to process the aleurone layer powder takes 2 to 10 minutes.

6. The application of the aleurone layer powder prepared according to any one of claims 1-5 in the preparation of aleurone-rich wheat flour, characterized in that, The method for preparing the aleurone-rich wheat flour is as follows: the wheat after conditioning and dehulling in (4) is milled by a milling machine; the aleurone-rich wheat flour prepared in (5) is compounded with the wheat flour prepared in (6) at a ratio of 5% to 20% of the aleurone-rich wheat flour.

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