Cereal whole grain and processing method thereof

Abstract

The invention belongs to the technical field of grain processing, and particularly relates to whole grains and a processing method thereof. The processing method of the whole grains comprises the following steps: mixing an acidic agent, an active agent and a dispersing agent in a pretreatment tank, and introducing supercritical carbon dioxide fluid to form a mixture; injecting the mixture fluid into a sealed reaction tank filled with the cereals, controlling the pressure to be 7.5-35MPa and the temperature to be 30-50 DEG C, keeping for 30-350min, and recovering carbon dioxide into the tank after second-stage pressure relief to obtain the cereals; and taking out the whole grains and drying to obtain the whole-grain whole-grain product. The processing method of the whole grains provided by the invention is simple to operate; the whole grain product processed by the method is high in dietary fiber utilization rate, short in cooking time and high in nutrient content.

Description

Technical Field

[0001] The invention belongs to the technical field of grain processing, and in particular relates to whole grains of cereals and a processing method thereof. Background Art

[0002] Whole grains are an important part of human diet. They are rich in dietary fiber, vitamins, minerals and various bioactive substances, and play an important role in maintaining human health. However, traditional whole grain processing methods often have problems such as nutrient loss, long cooking time and low dietary fiber utilization. Therefore, it is particularly important to develop a new processing technology that can efficiently retain nutrients, improve dietary fiber utilization and shorten cooking time.

[0003] "Whole grains are an anatomical structure concept, not a grain type concept. Simply put, any natural grain is an organic life form, consisting of three parts: endosperm, embryo and seed coat. Whole grains are the complete caryopsis grains that are left after only the inedible parts such as the husk are removed. They have complete endosperm, embryo and seed coat, and the yield rate is over 98%. If one or two of the components are removed, they cannot be called whole grains." Refined grains have their embryo and seed coat removed during processing, leaving only the endosperm part, which is what is commonly known as polished rice and white flour, and the product yield rate is only 65%-75%. Studies have shown that whole grains contain 40%-90% more B vitamins such as vitamin B1, B2, folic acid, niacin, and other B vitamins, as well as mineral elements such as calcium, iron, and zinc than refined grains, playing a key role in supporting brain function and maintaining normal metabolism.

[0004] Traditional grain processing methods usually use steam treatment and chemical soaking methods. Steam treatment usually needs to be carried out at high temperatures, which will lead to a large loss of heat-sensitive nutrients (such as vitamins, polyphenols, etc.). The chemical soaking method uses chemical reagents that react with the nutrients in the grains, resulting in the destruction or loss of nutrients. Traditional steaming methods often take a long time to make the grains reach the ideal degree of maturity, which not only increases energy consumption, but may also affect the taste and texture of the product. The chemical soaking method uses a large amount of water and organic solvents during the processing process, which not only increases production costs, but also pollutes the environment. Although steam treatment is relatively environmentally friendly, it has high energy consumption and will also increase production costs.

[0005] Therefore, these processes are not only energy-intensive, but also often need to be carried out under high temperature conditions, resulting in a large loss of heat-sensitive nutrients (such as vitamins, polyphenols, etc.). In addition, traditional methods often use a large amount of water and organic solvents during the treatment process, which not only increases production costs, but also brings environmental pollution problems.

[0006] In recent years, supercritical fluid technology has shown great application potential in the field of food processing due to its unique physical and chemical properties. 2 ) is one of the most commonly used supercritical fluids. It has the high diffusivity of gas and the high density of liquid. It can efficiently penetrate into the cells of grains and cereals to achieve rapid extraction and retention of ingredients. More importantly, SC-CO 2 It is gaseous at room temperature, easy to separate and recycle, environmentally friendly, and meets the requirements of green processing. 2 , because the polarity of supercritical carbon dioxide is relatively small, the extraction efficiency may be relatively low for substances with high polarity and molecular weight exceeding 500. This may require the use of an entrainer or extraction under very high pressure, thereby increasing the complexity and cost of the operation. CN113974048A discloses a supercritical wall-breaking treatment method for cereals and grains, which controls the carbon dioxide temperature at 32-45°C and the pressure at 8-55MPa, utilizes the property of supercritical carbon dioxide that can dissolve lipids, and infiltrates the seeds under high pressure. After 2-8 hours of action, the carbon dioxide pressure inside and outside the cells of the cereals and grains seeds reaches equilibrium. Although the cell wall breaking effect can be achieved, the processing process is long and the nutritional loss is relatively serious. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for processing whole grains of cereals, which is simple to operate; the whole grain products of cereals processed by the present invention have high dietary fiber utilization rate, short cooking time and high nutritional content.

[0008] The method for processing whole grains of cereals of the present invention comprises the following steps:

[0009] (1) introducing a supercritical carbon dioxide fluid with an entrainer, mixing an active agent, a dispersant, and an acidic agent in a pretreatment tank to form a supercritical mixture fluid;

[0010] (2) injecting the mixed fluid into a sealed reaction tank filled with grains and cereals, controlling the pressure to 7.5-35 MPa and the temperature to 30-50° C., and maintaining the temperature for 30-350 min;

[0011] (3) releasing the pressure into a carbon dioxide recovery tank in two stages to obtain the processed grains;

[0012] (4) taking out the cereals and grains, drying them, removing impurities and vacuum packaging them to obtain the whole cereals and grains.

[0013] The acidic agent is an organic acid, and the amount of the acidic agent added is 1% to 5% of the mass of the grains.

[0014] The acidic agent is glucono-δ-lactone.

[0015] The active agent is a surfactant, and the amount of the active agent added is 0.5% to 1.5% of the mass of the grains.

[0016] The active agent is monoglyceride or sucrose ester.

[0017] The dispersant is carboxymethyl cellulose or sodium carboxymethyl cellulose, and the added amount of the dispersant is 0.1% to 0.8% of the mass of the cereals.

[0018] The whole grains are one or more of paddy rice, brown rice, quinoa, sorghum rice, coix seed, wheat, buckwheat, oats, corn and miscellaneous beans, and the water content is 8% to 12%.

[0019] In the process of introducing supercritical carbon dioxide fluid in step (1), when adding active agent, dispersant and acidic agent respectively, an entrainer is added at the same time, the entrainer added to the active agent is ethanol, the entrainer added to the dispersant is water, and the entrainer added to the acidic agent is water, the total amount of ethanol and water accounts for 37.5% to 40% of the total mass of the active agent, dispersant and acidic agent, wherein the mass ratio of ethanol to water is 2.5:1 to 3:1.

[0020] Specifically, the method for processing whole grains of cereals comprises the following steps:

[0021] (1) introducing supercritical carbon dioxide fluid, mixing 0.5% to 1.5% of monoglyceride or sucrose ester by weight of cereals and grains, 0.1% to 0.8% of carboxymethyl cellulose or sodium carboxymethyl cellulose by weight of cereals and grains, and 1% to 5% of glucono-δ-lactone by weight of cereals and grains in a pretreatment tank to form a mixture;

[0022] (2) injecting the mixed fluid into a sealed reaction tank filled with cereals with a water content of 8% to 12%, evacuating the tank, controlling the pressure to 7.5-35 MPa, the temperature to 30-50° C., and maintaining the reaction time to 30-350 min;

[0023] (3) Perform two stages of pressure relief: in the first stage, the pressure is relieved at 1-3 MPa / min to a pressure of 5-15 MPa, and then maintained for 5-30 minutes; in the second stage, the pressure is relieved at 0.3-0.8 MPa / min to a normal pressure of 0.1 MPa;

[0024] The supercritical carbon dioxide mixture fluid efficiently penetrates into the cell tissue of grains and cereals, dissolving fat-soluble substances. When the supercritical carbon dioxide fluid is depressurized, the supercritical carbon dioxide fluid enters the gas phase and leaks out. The pressure difference inside and outside the cells will cause gaps in the cells. At the same time, the acid, active agent, and dispersant are evenly retained in the cracks. The first stage (rapid depressurization): destroys the grain epidermis and cell wall to form a microporous structure. The second stage (slow depressurization): maintains the integrity of the particles and reduces the loss of nutrients.

[0025] (4) taking out the whole grains and cereals, drying them, removing impurities and vacuum packaging them to obtain whole grain products that are easy to steam and cook.

[0026] The processing method of whole grains of cereals is completed by using a supercritical carbon dioxide generator, a pretreatment tank, a reaction tank and a pressure control module. The present invention utilizes the permeability of supercritical fluid. Supercritical fluid can penetrate into the cells of cereals. When the pressure is released, the pressure difference between the inside and outside of the cell will cause the cell wall to rupture, thereby achieving the purpose of breaking the wall. Acidic agents can soften cell walls and reduce the strength of cell walls, creating conditions for subsequent wall breaking and additive attachment; activators can enhance the permeability of fluids, allowing additives to better enter the cells; dispersants can prevent the components from agglomerating and ensure the uniformity of the mixed fluid. Low-temperature supercritical treatment can avoid the destruction of heat-sensitive components. By carrying out supercritical treatment under a low-temperature environment, the nutrients in cereals, such as vitamins, bioactive substances, etc., can be better retained, thereby improving the nutritional value of the product.

[0027] The present invention adopts supercritical carbon dioxide (SC-CO 2 ) is used as a processing medium to replace traditional water or organic solvents, and its high diffusion properties of gas (the diffusion coefficient is 100 times higher than that of liquid) and high density of liquid are utilized to achieve efficient penetration of the cell walls of grains and cereals and retention of components.

[0028] The operating temperature of the present invention is controlled at 30-50° C., so as to avoid high temperature destruction of heat-sensitive nutrients (such as vitamins and polyphenols). Compared with traditional steaming or high-temperature puffing processes, the dietary fiber retention rate is improved.

[0029] The invention adopts an acidic agent-active agent-dispersant ternary system and a synergistic action mechanism of composite additives. The acidic agent softens the cell wall lignin structure and reduces the mechanical strength. The surfactant enhances the solubility of the supercritical fluid for fat-soluble components. The dispersant prevents the starch and protein released after cell rupture from agglomerating.

[0030] The present invention uses two-stage pressure relief to drive the additive to adhere precisely to the cell rupture area and attach in a directional manner through pressure difference, thus forming a functional modified interface. The invention further adopts two-stage gradient pressure relief, wherein the first stage of rapid pressure relief induces microcracks in the cell wall, and the second stage of slow pressure relief achieves slow closure of the cell cavity to form a porous structure, which greatly improves the water molecule penetration efficiency during cooking and reduces energy consumption costs.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The processing method of whole grains of cereals and grains of the present invention is low-cost, green and environmentally friendly, and no water is involved in the whole process and no organic solvent residue is left.

[0033] (2) The whole grain products of cereals processed by the method of the present invention have an average steaming time shortened by 7.9% to 25%, a hardness value reduced by about 40% to 47.6%, an elasticity value increased by about 20% to 35%, a viscosity value increased by about 60% to 109%, and a taste close to or even better than that of rice. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with specific embodiments.

[0035] The raw materials used in the following examples and comparative examples are all commercially available products. The rice described below comes from the commercially available Jinlongyu Panjin rice. The rice cooker steaming method given in the package is "Take the rice and wash it lightly: add an appropriate amount of rice and water and wash it lightly; add water and steam: it is recommended that the ratio of rice to water after washing is between 1:1.1-1.3, which can be increased or decreased based on personal preference. If it is soaked for about 20 minutes before cooking, the taste will be better; Fragrant rice: choose the cooking mode as you like, it is recommended to simmer for a while after the rice is cooked, the taste will be better."

[0036] After pre-treatment of processed grain products, removing incomplete grains, broken grains, diseased grains and surface dust, the following experiments were conducted:

[0037] The experimental data are as follows. The cooking time refers to the time taken for the whole grains to be tested to be cooked until no white core appears. The hardness value is a numerical value indicating the hardness of the rice. The elasticity value is a numerical value indicating the elasticity of the rice. The stickiness value is a numerical value indicating the stickiness of the rice. The smaller the value, the less sticky the rice is and the less likely it is to form a ball.

[0038] The hardness, elasticity and viscosity values ​​were determined using a STA1A rice taste meter (Satake, Japan): After removing incomplete grains, broken grains, diseased grains and dust on the surface, 30.0 g were weighed, rinsed with water for 30 seconds, and steamed in a rice cooker. When no white core appeared, the cooking time was recorded. After cooking, simmered and cooled, 7 g was weighed and placed in a stainless steel sample ring with a diameter of 30 mm and a height of 9 mm. The rice was pressed into a rice cake with a rice press. The front and back of the sample were measured once each (2 times in total). The hardness, elasticity and viscosity values ​​of the samples were determined, and each sample was set up for 3 parallel times.

[0039] Example 1

[0040] The buckwheat processing method comprises the following steps:

[0041] (1) introducing supercritical carbon dioxide fluid, firstly mixing 1% sucrose ester with entrainer ethanol based on the mass of buckwheat, then mixing 0.6% carboxymethyl cellulose with entrainer water based on the mass of buckwheat, and finally mixing 3% glucono-δ-lactone with entrainer water based on the mass of raw material buckwheat in a pretreatment tank to form a mixture;

[0042] The total mass of the entrainer water and ethanol is 37.5% of the total mass of sucrose ester, carboxymethyl cellulose and glucono-δ-lactone, wherein the mass ratio of ethanol to water is 2.5:1, wherein the entrainer water is added in two parts in equal parts;

[0043] (2) injecting the mixed fluid into a sealed reaction tank filled with buckwheat having a water content of 8%, evacuating the tank, controlling the pressure to 30 MPa and the temperature to 32° C., and maintaining the pressure steady for 90 min;

[0044] (3) performing two stages of pressure release: in the first stage, the pressure is released at 2.3 MPa / min to a pressure of 6 MPa, and then maintained for 30 min. In the second stage, the pressure is released at 0.5 MPa / min to a normal pressure of 0.1 MPa, and the carbon dioxide is released into a recovery tank to obtain the treated whole grain buckwheat.

[0045] The test results of raw buckwheat, whole grain buckwheat and rice are shown in Table 1.

[0046] Table 1 Test results

[0047] project Cooking time / min Hardness value / kgf Elasticity value Viscosity value / kgf Raw buckwheat 38 6.7 0.54 0.43 Whole Grain Buckwheat 35 4.0 0.65 0.69 Rice 30 4.2 0.72 0.68

[0048] As can be seen from Table 1, after buckwheat treatment, the steaming time was shortened by 3 minutes; the hardness value decreased by 40.3%, the elasticity value increased by 20.4%, and the viscosity value increased by 60.5%. The indicators were greatly improved after treatment, and the taste indicators were basically the same as those of rice. At the same time, the original ingredients of buckwheat were retained, achieving the whole grain effect of cereals.

[0049] Example 2

[0050] The method for processing brown rice comprises the following steps:

[0051] (1) feeding supercritical carbon dioxide fluid, first 1.2% sucrose ester of brown rice quality is carried with entrainer ethanol, then 0.7% sodium carboxymethyl cellulose of brown rice quality is carried with entrainer water, and finally 3.5% glucono-delta-lactone of brown rice quality is carried with entrainer water, mixed in the pretreatment tank, to form a mixture;

[0052] The total mass of the entrainer water and ethanol is 40% of the total mass of sucrose ester, sodium carboxymethyl cellulose and glucono-δ-lactone, wherein the mass ratio of ethanol to water is 3:1, wherein the entrainer water is added in two parts in equal parts;

[0053] (2) injecting the mixed fluid into a sealed reaction tank containing brown rice having a water content of 12%, evacuating the tank, controlling the pressure to 26 MPa and the temperature to 35° C., and maintaining the pressure for 120 min;

[0054] (3) performing two stages of pressure release: in the first stage, the pressure is released at 1.8 MPa / min to a pressure of 5 MPa, and then maintained for 20 minutes; in the second stage, the pressure is released at 0.6 MPa / min to a normal pressure of 0.1 MPa, and the carbon dioxide is released into a recovery tank to obtain the treated whole grain brown rice.

[0055] The test results of raw brown rice, whole grain brown rice, and rice are shown in Table 2.

[0056] Table 2 Test results

[0057] project Cooking time / min Hardness value / kgf Elasticity value Viscosity value / kgf Raw brown rice 40 6.7 0.54 0.31 Whole grain brown rice 30 4.0 0.73 0.65 Rice 30 4.2 0.72 0.68

[0058] It can be seen from Table 2 that after the brown rice is processed, the steaming time is shortened by 10 minutes, which is basically the same as the steaming time of rice; the hardness value is reduced by 40.3%, the elasticity value is increased by 35.1%, and the viscosity value is increased by 109.7%. The indicators are greatly improved after treatment, and the taste indicators are basically the same as those of rice. At the same time, the original ingredients of brown rice are retained, achieving the effect of whole grains.

[0059] Example 3

[0060] The oat processing method comprises the following steps:

[0061] (1) introducing supercritical carbon dioxide fluid, firstly mixing 1.5% monoglyceride by mass of oats with entrainer ethanol, then mixing 0.8% carboxymethyl cellulose by mass of oats with entrainer water, and finally mixing 5% glucono-δ-lactone by mass of oats with entrainer water in a pretreatment tank to form a mixture;

[0062] The total mass of the entrainer water and ethanol is 40% of the total mass of monoglyceride, carboxymethyl cellulose and glucono-δ-lactone, wherein the mass ratio of ethanol to water is 3:1, wherein the entrainer water is added in two parts in equal parts;

[0063] (2) injecting the mixed fluid into a sealed reaction tank filled with oats having a water content of 10%, evacuating the tank, controlling the pressure to 28 MPa and the temperature to 32° C., and maintaining the pressure steady for 150 min;

[0064] (3) performing two stages of pressure release: in the first stage, the pressure is released at 2 MPa / min to a pressure of 7 MPa, and then maintained for 15 minutes. In the second stage, the pressure is released at 0.7 MPa / min to a normal pressure of 0.1 MPa, and the carbon dioxide is released into a recovery tank to obtain the treated whole grain oats.

[0065] The test results of raw oats, whole grain oats, and rice are shown in Table 3.

[0066] Table 3 Test results

[0067] project Cooking time / min Hardness value / kgf Elasticity value Viscosity value / kgf Raw oats 43 8.2 0.57 0.37 Whole grain oats 36.8 4.3 0.76 0.63 Rice 30 4.2 0.72 0.68

[0068] It can be seen from Table 3 that after oat processing, the cooking time was shortened by 6.2 min, the hardness value decreased by 47.6%, the elasticity value increased by 33.3%, and the viscosity value increased by 70.3%. The indicators were greatly improved after treatment, and the taste indicators were basically the same as those of rice. At the same time, the original ingredients of oats were retained, achieving the whole grain effect of cereals.

Claims

1. A method for processing whole grains of cereals, characterized in that: The following steps are involved: (1) introducing a supercritical carbon dioxide fluid with an entrainer, mixing an active agent, a dispersant, and an acidic agent in a pretreatment tank to form a supercritical mixture fluid; (2) injecting the mixed fluid into a vacuum and sealed reaction tank filled with cereals and grains, controlling the pressure to 7.5-35 MPa and the temperature to 30-50° C., and maintaining the temperature for 30-350 min; (3) releasing the pressure into a carbon dioxide recovery tank in two stages to obtain the processed grains; (4) taking out the cereals and grains, drying them, removing impurities and vacuum packaging them to obtain the whole cereals and grains.

2. The method for processing whole grains of cereals according to claim 1, characterized in that: The acidic agent is an organic acid, and the amount of the acidic agent added is 1% to 5% of the mass of the grains.

3. The method for processing whole grains of cereals according to claim 1, characterized in that: The acidic agent is glucono-δ-lactone.

4. The method for processing whole grains of cereals according to claim 2, characterized in that: The active agent is a surfactant, and the amount of the active agent added is 0.5% to 1.5% of the mass of the grains.

5. The method for processing whole grains of cereals according to claim 3, characterized in that: The active agent is monoglyceride or sucrose ester.

6. The method for processing whole grains of cereals according to claim 4, characterized in that: The dispersant is carboxymethyl cellulose or sodium carboxymethyl cellulose, and the added amount of the dispersant is 0.1% to 0.8% of the mass of the cereals.

7. The method for processing whole grains of cereals according to claim 1, characterized in that: The whole grains are one or more of paddy rice, brown rice, quinoa, sorghum rice, coix seed, wheat, buckwheat, oats, corn and miscellaneous beans, and the water content is 8% to 12%.

8. The method for processing whole grains of cereals according to claim 1, characterized in that: The two-stage pressure relief in step (3) is as follows: the first stage is to release the pressure at 1-3 MPa / min to a pressure of 5-15 MPa, and then maintain the pressure for 5-30 minutes; the second stage is to release the pressure at 0.3-0.8 MPa / min to normal pressure.

9. The method for processing whole grains of cereals according to claim 1, characterized in that: In the process of introducing supercritical carbon dioxide fluid in step (1), when the active agent, dispersant and acidic agent are added respectively, an entrainer is added at the same time, the entrainer of the active agent is ethanol, the entrainer of the dispersant is water, and the entrainer of the acidic agent is water, the total amount of ethanol and water accounts for 37.5% to 40% of the total mass of the active agent, the dispersant and the acidic agent, and the mass ratio of ethanol to water is 2.5:1 to 3:

1.

10. A whole grain cereal, characterized in that: The whole grains are obtained by the processing method of whole grains according to any one of claims 1 to 9.