Grain storage method and application thereof

Abstract

The invention belongs to the technical field of grain storage, and particularly relates to a grain storage method and application thereof. The invention provides a grain storage method, which comprises air conditioning agent storage or air conditioning storage, and adopts a specific air conditioning agent or air conditioning gas to store grains including unhusked rice and brown rice, so that the quality and freshness of the grains can be guaranteed, the grain storage quality, the grain activity and the eating quality are effectively guaranteed, and the grain storage quality is improved. The shelf life can also be prolonged; on the basis, the method is combined with a low-temperature environment to play a more positive role in promoting the quality and freshness of the grains, for example, the moisture of the grains is better maintained, the gelatinization characteristic index of the rice is inhibited from becoming worse, and the fatty acid value of the brown rice is continuously increased. Meanwhile, the method is more suitable for small-package storage and transportation of the grains, circulation of the grains is facilitated, and the method has great significance in researching and guaranteeing portable storage and transportation of packaged finished grains and semi-finished grains and guaranteeing the quality of the grains at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of grain storage, and in particular relates to a grain storage method and application thereof. Background Art

[0002] Rice is the main storage grain in my country. With the increase of rice inventory in recent years, the existing grain storage capacity is difficult to meet the demand. [1] . Brown rice is the grain after the rice is husked. The bran and germ of brown rice contain rich nutrients such as lipids, vitamins, and minerals. As the public's demand for food nutrition and health increases, brown rice is gradually gaining popularity. In addition, compared with rice, brown rice can theoretically save about 20% of storage space. Compared with rice, it can save storage space and is also a good emergency reserve semi-finished grain. [2] However, the lipids in brown rice are easily oxidized during normal storage, producing free fatty acids, aldehydes, ketones and other undesirable substances. [3] , reducing its nutritional value and shortening its storage time.

[0003] Low temperature storage can reduce the activity of various enzymes involved in biochemical reactions in grains, which is beneficial to ensuring grain quality. [4 , 5] , controlled atmosphere changes the composition of the ambient gas, that is, by reducing the oxygen concentration, slowing down the oxidation of lipids and inhibiting food metabolism, thereby extending the storage time of food and ensuring the quality of brown rice. [6,7] Low-temperature controlled atmosphere is a promising storage method. After harvest, rice is dried, impurities removed and stored in the national grain reserve warehouse as raw grain. The grain reserve warehouse generally controls the warehouse temperature at a low temperature of 15°C or a quasi-low temperature of 20°C to store rice, which can effectively ensure the quality of rice. At present, my country's grain warehouse controlled atmosphere storage is mainly divided into carbon dioxide controlled atmosphere storage and nitrogen controlled atmosphere storage. Due to the high content of nitrogen in the air and its easy availability, nitrogen controlled atmosphere storage is mainly used in existing grain warehouses. However, this process requires the use of nitrogen generators and nitrogen filling pipelines and has certain requirements for the air tightness of the warehouse. This has restrictions such as high cost and high technical content for the controlled atmosphere storage and transportation of small batches of rice, and it is difficult to promote and apply it in the field of storage and circulation of small-packaged rice and brown rice. Summary of the invention

[0004] The purpose of the present invention is to provide a grain storage method and application thereof, wherein the method is suitable for the storage of small-packaged grains and the short-term transportation of grains, and can achieve the effect of preserving the quality and freshness of grains.

[0005] The present invention provides a method for grain storage, including gas conditioning storage or controlled atmosphere storage;

[0006] The gas conditioning agent storage comprises the following steps: placing the gas conditioning agent and food in a double-layer packaging device, and sealing and preserving them;

[0007] The gas conditioning agent comprises the following components in percentage by weight: 75% to 85% iron powder, 1% to 4% activated carbon, 1% to 4% diatomaceous earth, 1% to 5% zeolite powder, 0.1% to 5% sulfate, 2% to 6% bicarbonate, 0.5% to 2% sulfite and 1% to 8% water, the sum of the components of the gas conditioning agent being 100%;

[0008] The controlled atmosphere storage comprises the following steps: placing the grain in a fresh-keeping device containing controlled atmosphere gas, and sealing and preserving the grain;

[0009] The gas for regulating the atmosphere includes nitrogen and oxygen, and the volume ratio of the oxygen to the nitrogen is 0-1:9-10.

[0010] Preferably, during the storage of the atmosphere-adjusting agent, the weight ratio of the atmosphere-adjusting agent to the grain is (1-2):1250.

[0011] Preferably, in the atmosphere-controlled storage, the double-layer packaging device comprises an inner packaging and an outer packaging, the inner packaging is made of nylon or polyethylene plastic, and the outer packaging is made of kraft paper or corrugated cardboard.

[0012] Preferably, the double-layer packaging device includes a double-layer packaging bag or a double-layer packaging carton; the thickness of the plastic is 8 to 12 filaments.

[0013] Preferably, in the controlled atmosphere storage, the weight of the grain and the volume of the controlled atmosphere gas are in the ratio of 1-25 kg: 0.02-0.025 m 3 .

[0014] Preferably, the fresh-keeping device comprises a fresh-keeping box, and the material of the fresh-keeping box comprises a high-barrier material.

[0015] Preferably, the specifications of the modified atmosphere storage and the controlled atmosphere storage are 0.5kg to 25kg / packaging device, respectively.

[0016] Preferably, the temperatures of the modified atmosphere storage and the controlled atmosphere storage are 15-20°C, respectively.

[0017] Preferably, the food comprises paddy and / or brown rice.

[0018] The present invention also provides application of the method described in the above technical solution in grain transportation.

[0019] Beneficial effects:

[0020] The present invention provides a method for grain storage, including gas conditioning storage or gas conditioning storage. The present invention uses a specific gas conditioning agent or gas conditioning gas to preserve grains including paddy and brown rice, which can achieve the quality preservation and freshness of grains. In addition to effectively ensuring the storage quality, grain activity and edible quality of grains, it can also extend its shelf life; on this basis, it can play a more positive role in promoting the quality preservation and freshness of grains in combination with a low temperature environment, such as better maintaining the moisture of grains, inhibiting the deterioration of rice gelatinization characteristic indicators, and delaying the increase of brown rice fatty acid value. At the same time, the method of the present invention is more suitable for small-package storage and transportation of grains, which is convenient for the circulation of grains, and is of great significance for researching and ensuring the portable storage and transportation of packaged finished grains and semi-finished grains while ensuring the quality of grains. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0022] Figure 1 The temperature, humidity and oxygen conditions of the atmosphere-controlled brown rice high temperature accelerated experiment in Example 1;

[0023] Figure 2 The effect of different gas conditioning agent contents on the fatty acid value of brown rice in Example 1;

[0024] Figure 3 The moisture content of rice during the gas-controlled storage in Example 1 is shown in FIG.

[0025] Figure 4 The change of fatty acid value of rice during controlled atmosphere storage in Example 1;

[0026] Figure 5 The germination rate of rice during the controlled atmosphere storage in Example 1 is changed;

[0027] Figure 6 The changes in moisture content, germination rate and fatty acid value of brown rice during low temperature storage at 15°C in Example 2;

[0028] Figure 7 The change of brown rice moisture over time at different storage temperatures in Comparative Example 1;

[0029] Figure 8 The change of fatty acid value of brown rice at different storage temperatures over time in Comparative Example 1;

[0030] Fig. 9 The figure shows the change of germination rate of brown rice over time at different storage temperatures in Comparative Example 1. DETAILED DESCRIPTION

[0031] The present invention provides a method for grain storage, including gas conditioning storage or controlled atmosphere storage;

[0032] The gas conditioning agent storage comprises the following steps: placing the gas conditioning agent and food in a double-layer packaging device for sealed storage;

[0033] The gas conditioning agent comprises the following components in percentage by weight: 75% to 85% iron powder, 1% to 4% activated carbon, 1% to 4% diatomaceous earth, 1% to 5% zeolite powder, 0.1% to 5% sulfate, 2% to 6% bicarbonate, 0.5% to 2% sulfite and 1% to 8% water, the sum of the components of the gas conditioning agent being 100%;

[0034] The controlled atmosphere storage comprises the following steps: placing the grain in a fresh-keeping device containing controlled atmosphere gas, and sealing and preserving the grain;

[0035] The gas for regulating the atmosphere includes nitrogen and oxygen, and the volume ratio of the oxygen to the nitrogen is 0-1:9-10.

[0036] In the present invention, the atmosphere-adjusting agent storage comprises the following steps: placing the atmosphere-adjusting agent and food in a double-layer packaging device, and sealing and preserving them.

[0037] In terms of weight percentage, the gas conditioning agent of the present invention comprises 75% to 85% iron powder, preferably 78% to 83%; the iron powder is preferably reduced iron powder; the iron powder has the function of reducing oxygen and absorbing water. The gas conditioning agent of the present invention comprises 1% to 4% activated carbon, preferably 2% to 3% activated carbon; the activated carbon has the function of deodorizing. The gas conditioning agent of the present invention comprises 1% to 4% diatomaceous earth, preferably 2% to 3%; the diatomaceous earth has the function of balancing moisture. The gas conditioning agent of the present invention comprises 1% to 5% zeolite powder, preferably 2% to 4%; the zeolite powder has the function of regulating environmental humidity. The gas conditioning agent of the present invention comprises 0.1% to 5% sulfate, preferably 1% to 4%, and more preferably 2% to 3%; the sulfate is preferably sodium sulfate, and the sulfate has the function of absorbing moisture. The gas conditioning agent of the present invention comprises 2% to 6% of bicarbonate, preferably 3% to 5%, and more preferably 3.5% to 4%; the bicarbonate is preferably sodium bicarbonate, and the bicarbonate has the function of releasing carbon dioxide. The gas conditioning agent of the present invention comprises 0.5% to 2% of sulfite, preferably 1% to 1.5%; the sulfite is preferably sodium sulfite, and the sodium sulfite has the function of absorbing oxygen. The gas conditioning agent of the present invention comprises 1% to 8% of water, preferably 2% to 7%, and more preferably 3% to 5%.

[0038] The gas conditioning agent of the present invention is preferably coated with a coating material and then placed in the double-layer packaging device, and the coating material is preferably coated on the surface of the gas conditioning agent. In terms of weight percentage, the coating material of the present invention preferably includes the following weight percentage components: 30-35% of nylon paper, 45%-55% of low-density polyethylene (LDPE) and 10%-15% of polyethylene terephthalate (PET).

[0039] The present invention has no special limitation on the preparation method of the gas conditioning agent, and the coating can be achieved by mixing the components according to the above mass percentages and referring to the conventional coating methods in the art.

[0040] The weight ratio of the gas conditioning agent to the food of the present invention is preferably (1-2): 1250, more preferably (1.5-2): 1250. The food of the present invention preferably includes rice and / or brown rice, more preferably rice or brown rice, and more preferably brown rice.

[0041] The double-layer packaging device of the present invention preferably includes an inner packaging and an outer packaging, and the material of the inner packaging is preferably a plastic made of nylon (PA) or polyethylene (PE); the thickness of the plastic is preferably 8 to 12 filaments, more preferably 12 filaments; the material of the outer packaging is preferably kraft paper or corrugated cardboard. The double-layer packaging device of the present invention preferably includes a double-layer packaging bag or a double-layer packaging carton, and more preferably a double-layer packaging bag. The double-layer packaging device of the present invention is impermeable to water and air to ensure good air tightness of the double-layer packaging device, increase the hygroscopicity of the packaging device to the storage environment and the wear resistance of the material.

[0042] The controlled atmosphere storage of the present invention comprises the following steps: placing the grain in a fresh-keeping device containing controlled atmosphere gas, and sealing and preserving. The controlled atmosphere gas of the present invention comprises nitrogen and oxygen, and the volume ratio of oxygen to nitrogen is preferably 0-1:9-10, more preferably 1:9. The weight of the grain of the present invention and the volume ratio of the controlled atmosphere gas are preferably 1-25 (kg): 0.02-0.025 m 3 , more preferably 25kg: 0.022m 3. The fresh-keeping device of the present invention preferably includes a fresh-keeping box or a fresh-keeping bag, and the material of the fresh-keeping box preferably includes a high barrier material, and more preferably polypropylene and polyester composite plastics (PP+PET). When sealed according to the present invention, the material of the sealing film of the fresh-keeping box is preferably polypropylene, polyethylene and ethylene-vinyl alcohol copolymer composite film (PP+PE+EVOH). The grain of the present invention preferably includes rice and / or brown rice, and more preferably rice or brown rice, and more preferably brown rice. The specifications of the atmosphere-controlled storage and the atmosphere-controlled storage of the present invention are preferably 0.5kg~25kg / packaging device, more preferably 1kg~25kg / packaging, and more preferably 2.5~10kg / packaging, that is, the method of the present invention is more suitable for small package storage of grain, so as to facilitate the storage and transportation of grain.

[0043] The temperatures of the modified atmosphere storage and the controlled atmosphere storage of the present invention are preferably 15-20°C, further preferably 15-18°C, and more preferably 20°C, that is, the method of the present invention is more preferably combined with low-temperature preservation on the basis of modified atmosphere storage and controlled atmosphere storage, and its effect is better.

[0044] The present invention also provides an application of the method described in the above technical solution in grain transportation. The grain described in the present invention preferably includes rice and / or brown rice, more preferably rice or brown rice, and more preferably brown rice. The grain storage method based on the above technical solution of the present invention, especially the storage method of small packages, can realize the portable transportation of grain. For example, in practical applications, the gas conditioning storage or gas conditioning storage can be transported in combination with a movable low-temperature storage device to ensure the shelf life and quality of the grain.

[0045] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0046] Example 1

[0047] A method for storing grain gas adjustment, comprising the following steps:

[0048] 1) Composition and preparation method of gas conditioning agent:

[0049] The gas conditioning agent is composed of the following components in weight percentage: 80% iron powder, 3% activated carbon, 2.5% diatomaceous earth, 3% zeolite powder, 2.5% sodium sulfate, 3.5% sodium bicarbonate, 1.5% sodium sulfite and 4% water.

[0050] The surface of the gas conditioning agent is coated with packaging materials, which are composed of 30-35% of nik paper, 45-55% of low-density polyethylene (LDPE) and 10-15% of polyethylene terephthalate (PET), and the sum of the three components is 100%.

[0051] After mixing the components in the gas-adjusting agent, they are quickly coated. The production of gas-adjusting agent packaging meets one or more requirements of GB / T10004-2008 "Plastic composite film and bag dry composite and extrusion composite for packaging", GB / T21302-2007 "General rules for composite film and bag for packaging", and GB / T4456-2008 "Polyethylene blown film for packaging". The general method of coating the gas-adjusting agent is that the coating material is crushed by a crusher, melted by a melter, and the molten plastic is pressed into a mold with a hole by an extruder to form a solid film, and then cooled, surface treated, seamed, pressed and cut. Finally, the gas-adjusting agent is packaged in a body-fitting manner and vacuum-sealed in time to prevent the gas-adjusting agent from reacting with oxygen in the air. In addition, all other packaging materials that can meet the requirements of gas-adjusting coating materials, can effectively wrap the gas-adjusting agent, can react with the external environment through the micropores of the packaging materials during use to achieve gas-adjusting effect, and will not damage the packaging during packaging and transportation meet the requirements, and no special requirements are made for this part.

[0052] 2) Selection of packaging device

[0053] Choose a plastic woven bag with PP (polypropylene) inner layer commonly used for packing 25kg rice or brown rice on the market, fill the bag with air and seal it with a bag sewing machine to observe the air tightness. It is found that the packaging volume is significantly reduced 3 hours after inflation, indicating that the gas sealing of conventional plastic woven bags is poor. Therefore, this type of bag is not selected for modified atmosphere packaging.

[0054] Select airtight, watertight and airtight PA / PE (nylon and polyethylene copolymer) transparent packaging material as the inner packaging bag and kraft paper bag as the outer packaging bag. The specific application is as shown in step 3).

[0055] 3) The steps for brown rice storage by gas conditioning are as follows:

[0056] The same batch of Northeast japonica rice harvested in the autumn of 2022 was purchased, with an initial moisture content of 14±0.5% (wet basis). After the rice husk was removed by the rice husker, it was packaged into PA / PE transparent packaging bags with a single layer thickness of 12 threads and good airtightness. Each bag contained 25±0.1 kg of brown rice. The control group (CK) was taken as the control group without gas adjustment, and the experimental group one (T1), experimental group two (T2), and experimental group three (T3) were added with 40g, 30g, and 20g gas adjustment, respectively. After the temperature, humidity and oxygen detection equipment was placed in the bag of each experimental group, the inner packaging was sealed with a sealing machine, and the kraft paper bag outside the inner packaging was sealed with a sewing machine. After stacking, it was placed in a high temperature and high humidity area (Shenzhen) from early April 2023. The average temperature during the sample placement was 30°C, and the average relative humidity RH was 80%, so as to carry out the accelerated atmosphere storage experiment of brown rice. The temperature, humidity and oxygen conditions of the brown rice during the placement period are as follows Figure 1 shown.

[0057] After the brown rice was stored for 2 months, samples were taken from the broken bags of each group and analyzed for key quality indicators, which were fatty acids and gelatinization properties.

[0058] 3.1 Determination and results of brown rice fatty acid value:

[0059] The fatty acids in each group of brown rice were tested using the method in Appendix A of GB / T 20569-2006 "Rules for Determining Storage Quality of Rice". Figure 2 shown.

[0060] Fatty acid value is a representation of the degree of lipid oxidation in brown rice and an important indicator for evaluating the quality of brown rice. Figure 2 It can be seen that the fatty acid values ​​of the experimental group with added gas conditioning agent were all reduced compared with the control group without added gas conditioning agent and stored naturally. Specifically, the fatty acid value of brown rice with 40g gas conditioning agent added (which can reduce the oxygen content in the brown rice modified atmosphere packaging to below 2%) was significantly different from that of the control group, with an average difference of 8mgKOH / 100g. The fatty acid values ​​of the experimental groups T1 and T2 were also reduced compared with the control group, but the changes were not significant, with an average difference of 1-1.6mgKOH / 100g.

[0061] 3.2 Determination and results of brown rice gelatinization characteristics:

[0062] The gelatinization characteristics of each group of brown rice were tested using GB / T 24852-2010 "Rapid viscometer method for determination of gelatinization characteristics of rice and rice flour" and calibrated on a 14% wet basis using the TCW software Standard 1 provided by the Perton RVA4500 instrument. The results are shown in Table 1.

[0063] Table 1 Analysis of the effects of different contents of gas conditioning agents on the gelatinization characteristics of brown rice

[0064]

[0065]

[0066] Note: Different letters in the same column of each group represent differences, and the difference is P < 0.05.

[0067] The main component of brown rice is starch. The determination of the gelatinization characteristics of brown rice flour can replace the rice cooking method to reflect the edible quality of brown rice. Peak viscosity reflects the ability of starch to bind water, and high-temperature storage conditions have a greater impact on its peak viscosity; minimum viscosity is the minimum viscosity value of starch paste during cooling; decay value is the most sensitive indicator of gelatinization properties. The larger its value, the worse the high-temperature stability and the easier it is for starch granules to break; final viscosity represents the gelatinization degree of cold paste. As its value increases, the viscosity of rice decreases and the hardness increases; regeneration value represents the stability and aging trend of starch cold paste. The larger the regeneration value, the easier the rice is to age and the worse the edible quality. As shown in Table 1, compared with the control group, the peak viscosity, minimum viscosity, final viscosity and regeneration value of each experimental group were significantly reduced. In general, the starch gelatinization characteristics of brown rice in the control group were slightly worse, and the gelatinization indicators of brown rice after gas conditioning treatment were better.

[0068] 4) Storage of rice by gas conditioning, the steps are as follows:

[0069] The same batch of high-quality japonica rice (variety: Zhongkefa No. 5) was purchased for delivery in the fall of 2021, and the rice gas conditioning experiment was started in May 2022. After 2 months of vacuum insecticide treatment (oxygen concentration is less than 2%), the corrugated carton was sealed with a single-layer PA / PE transparent plastic film with a thickness of 8 threads that is airtight, watertight, and has good airtightness. In order to facilitate the removal of samples, the rice placed in the carton was divided into 3 open No. 9 self-sealing bags, and the weight of the rice was about 2Kg. The carton is a double corrugated carton with a length of 39cm, a width of 28cm, a height of 20cm, and a corrugated thickness of 0.5cm.

[0070] The rice grains that were placed in the open plastic film without adding gas conditioning in the cartons after vacuum insecticide treatment and stored naturally were used as the control group CK, and the rice grains that were placed in the plastic film sealed with sufficient gas conditioning (50g) in the cartons after vacuum insecticide treatment at the same temperature were used as the experimental group. The experimental groups with different oxygen concentrations in the sealed cartons adjusted to 0-2%, 2%-6%, 6%-10%, 10%-15%, and 15%-21% were named as experimental groups A, B, C, D, and E. The experimental group and the control group, a total of 6 groups of rice grains, were stored in a constant temperature environment of 20℃ and 25℃ for 15 months. Samples were taken once a month in the first 3 months, and once every 3 months thereafter. The moisture, germination rate, fatty acid value, and gelatinization characteristics of the sampled rice grains were tested and analyzed.

[0071] 4.1 The results of rice moisture changes are as follows Figure 3 shown.

[0072] Depend on Figure 3It can be seen that the moisture content of rice in each group showed a downward trend as the storage time of controlled atmosphere increased. When the storage environment temperature was 25℃ and 20℃, the moisture content of rice in CK group decreased significantly compared with the moisture content of each experimental group at the same temperature; among them, the rice in CK group at 25℃ had the largest change after 6 months of storage compared with the experimental group in the same environment at the same time, and the maximum difference in moisture content was 3.5%; the moisture content of rice in each experimental group generally showed a slow downward trend during storage, but the change before and after was not significant, indicating that PA / PE transparent plastic film sealing and aeration adjustment has a certain water retention and water holding capacity for stored rice.

[0073] 4.2 Changes in fatty acid values ​​in rice Figure 4 shown.

[0074] like Figure 4 As shown, the fatty acid values ​​of each treatment group and the control group at 20℃ and 25℃ ambient temperatures fluctuated within a small range during the 12-month storage period, but they increased slightly overall, which is consistent with the rule that the fatty acid value of rice increases with the extension of storage time. The fatty acid values ​​of rice in each group showed a significant upward trend when stored for 9 months, which was slightly higher than that when stored for 1 month, and the increase range was between 2 and 6 mg KOH / 100g; during the storage period of 12 months, the fatty acid value varied in a small range, and there was no significant difference between the treatment groups and the control group, indicating that the PA / PE transparent plastic film sealing and aeration adjustment had no significant inhibitory effect on the increase in the fatty acid value of stored rice. This is also related to the more suitable storage environment temperature of rice and the low moisture content of rice. Increasing the storage time should result in differences between the experimental group and the control group. However, the fatty acid values ​​of rice stored for 15 months are currently within the safe storage range specified by the national standard. [8] .

[0075] 4.3 The results of rice germination rate change are as follows Figure 5 shown.

[0076] Depend on Figure 5 It can be concluded that the germination rate of each treatment group decreased as the storage time increased, and the 25℃-CK group decreased most significantly, from 83.25% at the beginning of storage to 54.5% after 12 months of storage; the germination rate of the other treatment groups decreased with the increase of storage period at 20℃ and 25℃ ambient temperatures, and the 25℃-CK group decreased significantly after 6 months of storage; the germination rate of each experimental group showed a significant downward trend after 9 months of storage, with the maximum decrease of about 30%. This shows that PA / PE transparent plastic film sealing and aeration can protect the activity of stored rice grains, and the germination rate of rice grains in each experimental group is significantly improved compared with the control group.

[0077] 4.4 The results of changes in rice gelatinization characteristics are shown in Table 2.

[0078] Table 2 Data on the gelatinization characteristics of rice at different storage times and different controlled atmosphere temperatures

[0079]

[0080]

[0081]

[0082]

[0083] Note: Different letters in the same column of groups at the same temperature and time represent differences.

[0084] The gelatinization characteristics of starch are an important method for judging the quality of rice cooking and processing: the peak viscosity reflects the ability of starch to bind water; high temperature storage conditions have a greater impact on its peak viscosity; the minimum viscosity is the minimum viscosity value of starch paste during cooling; the decay value is the most sensitive indicator of gelatinization properties, and the larger its value, the worse the high temperature stability and the easier it is for starch granules to break; the final viscosity represents the gelatinization degree of cold paste, and the larger its value, the lower the viscosity of rice and the higher the hardness; the regeneration value represents the stability and aging trend of cold starch paste, and the larger the regeneration value, the easier the rice is to age and the worse the edible quality. From the analysis of the gelatinization characteristics of rice milled from rice in each experimental group and control group at two storage temperatures of 20℃ and 25℃ in Table 2, it can be seen that the gelatinization characteristics of each group of samples at 20℃ are better than those of rice sampled at 25℃ at the same time, which is consistent with the rule that high temperature causes rice aging and quality deterioration. For rice in different sampling groups with the same storage time and temperature, there are significant differences in peak viscosity and recovery value indicators, most of which are differences between the control group and the experimental group, indicating that controlled atmosphere can delay the deterioration of rice starch gelatinization characteristics. In the later sampling period, when the temperature and storage time are the same, there are significant differences in the attenuation values ​​between different groups when the temperature is the same. The higher the temperature, the more significant the difference in attenuation value.

[0085] In general, the gelatinization characteristics of rice will deteriorate as the storage temperature increases, while the gelatinization indicators of rice treated with controlled atmosphere remain better than those of the control group.

[0086] Example 2

[0087] The steps for low-temperature controlled atmosphere storage of grain are as follows:

[0088] 1. Specific implementation steps:

[0089] The grains were sealed with nitrogen atmosphere using airtight and well-sealed packaging materials (sealed bags, airtight fresh-keeping boxes, etc.), and sealed brown rice in a natural environment was used as a control. The two groups of sealed brown rice were stored in a low-temperature environment of 15°C. The quality differences between low-temperature gas storage and low-temperature storage were compared in a low-temperature environment.

[0090] 2. Brown rice low temperature controlled atmosphere storage experiment, the steps are as follows:

[0091] In 2023, the same batch of japonica brown rice received in the season was purchased from Harbin Jiahegu Agricultural and Forestry Products Co., Ltd., with an initial moisture content of 12.95±0.15% (wet basis). The brown rice was sealed in a fresh-keeping box with a specification of 200mm×140mm×60mm under natural environment, and each box contained 500±50g of brown rice. The mixed gas of air (control group, recorded as CK) and 10% O2+90% N2 (volume ratio) was recorded as treatment group T. The two gases were used by a manual desktop modified atmosphere packaging machine (Chengdu Luodiboer Equipment Co., Ltd., model: RDT320P) to adjust the atmosphere and seal the brown rice in the fresh-keeping box using the instrument's high-precision replacement technology (gas replacement rate 99.9%). The thickness of the sealing film is 8 filaments, and the materials of the fresh-keeping box and the sealing film are high-barrier materials of PP+PET and PP+PE+EVOH, respectively, to ensure that the gas composition of the brown rice and the humidity in the box during storage are not affected by the external environment. The sealed brown rice was divided into two groups according to the different gas composition and stored in a constant temperature environment of 15℃. Samples were taken every other month, with three parallels in each group, and the main quality indicators of the two groups of brown rice during the 6-month storage period were measured and observed: moisture, fatty acid value, germination rate and gelatinization characteristics.

[0092] 3. Test results

[0093] 3.1 The results of changes in brown rice moisture content, germination rate and fatty acid value are as follows Figure 6 shown.

[0094] The moisture changes of brown rice in the control group (CK) and the controlled atmosphere group (T) during storage at 15℃ for 6 months are shown in Figure 2. Figure 6 As shown by the black broken line. As can be seen from the figure, the moisture content of the two groups of brown rice fluctuated up and down during storage, but remained stable overall without significant differences, and the moisture content was basically between 13% and 13.5% (wb), indicating that compared with natural low-temperature storage during storage, low-temperature gas conditioning had no effect on the moisture content of brown rice.

[0095] The germination rate of brown rice during storage at 15℃ is as follows Figure 6As shown by the red line, the germination rates of the two groups of brown rice during low-temperature storage were at a high level, ranging from 75% to 89%. It is worth noting that at the first month of storage, the germination rate of the CK control group was higher (89%), while the germination rate of the controlled atmosphere group was lower than that of the CK group (84.5%). From the second month, the germination rates of the control group and the controlled atmosphere group dropped to the same level (79.5%), and then the germination rate of the controlled atmosphere group was higher than that of the control group. Until the sixth month of storage, the germination rates of the control group and the controlled atmosphere group were 79.5% and 86%, respectively, indicating that low-temperature controlled atmosphere has a promoting effect on maintaining the activity of brown rice grains.

[0096] Fatty acid value is an important quality for evaluating the quality of grain. The changes in fatty acid values ​​of the two groups of brown rice samples during storage are as follows: Figure 6 As shown by the blue broken line. As can be seen from the figure, the fatty acid values ​​of the brown rice in the two groups showed a fluctuating growth trend with the extension of storage time. Except for the fatty acid value of the brown rice in the gas-controlled group which was slightly higher than that of the control group by 2.32 mg KOH / 100 g after 5 months of storage, the fatty acid value of the brown rice in the control group was higher than that of the gas-controlled group during the rest of the storage time. After 6 months of storage, the fatty acid value of the brown rice in the control group reached 34.52 mg KOH / 100 g, while the fatty acid value of the brown rice in the gas-controlled group was 32.95 mg KOH / 100 g, which was lower than that of the control group, indicating that gas-controlled group had a positive effect on inhibiting the increase of the fatty acid value of brown rice.

[0097] 3.2 The results of changes in brown rice gelatinization characteristics are shown in Table 3.

[0098] Table 3 Gelatinization characteristics of brown rice during 6-month storage in low-temperature controlled atmosphere

[0099]

[0100] The gelatinization characteristics of starch are an important method to judge the quality of rice cooking and processing: the peak viscosity reflects the ability of starch to bind water; high-temperature storage conditions have a greater impact on its peak viscosity; the minimum viscosity is the minimum viscosity value of the starch paste during cooling; the attenuation value is the most sensitive indicator of gelatinization properties. The larger the value, the worse the high-temperature stability and the easier it is for starch granules to break; the final viscosity represents the gelation degree of the cold paste. As its value increases, the viscosity of the rice decreases and the hardness increases; the recovery value represents the stability and aging trend of the starch cold paste. The larger the recovery value, the easier it is for the rice to age and the worse the edible quality.

[0101] From the analysis of the gelatinization characteristics of brown rice in the control group and the controlled atmosphere group in Table 3, it can be seen that, except for the attenuation value, the peak viscosity, minimum viscosity, and final viscometer recovery value of the two groups of brown rice increased slightly during the 6-month storage at 15℃ low temperature, indicating that the edible quality of the two groups of brown rice decreased slightly with the extension of storage time. Through statistical analysis, it can be seen that during the 5-month storage, the peak viscosity and the final viscosity of the minimum viscometer in the gelatinization indexes of the two groups of brown rice had little difference, and the recovery value of the controlled atmosphere group was slightly lower than that of the control group and showed differences; when stored for 6 months, the minimum viscosity and final viscosity of the brown rice in the controlled atmosphere group were slightly lower than those of the control group. Comprehensive analysis shows that the gelatinization index of brown rice changed little during the low-temperature storage at 15℃, but the edible quality of brown rice stored for 6 months showed a trend of deterioration compared with the initial storage period. The controlled atmosphere can further inhibit the deterioration of the edible quality of brown rice on the basis of low-temperature storage. That is, controlled atmosphere low-temperature storage can be used as one of the measures to preserve the quality and freshness of rice.

[0102] Comparative Example 1

[0103] The steps for low temperature storage of grain are as follows: 1. Specific implementation method:

[0105] Use airtight and well-sealed packaging materials (sealed bags, airtight fresh-keeping boxes, etc.) to seal the grains, and store them in storage environments with different temperatures. According to previous studies, when the grain storage temperature is lowered, the grain respiration is weakened, and low temperature can delay the deterioration of grain quality.

[0106] 2. Brown rice low temperature storage experiment, the steps are as follows:

[0107] In 2023, the same batch of japonica brown rice received in the season was purchased from Harbin Jiahegu Agricultural and Forestry Products Co., Ltd., with an initial moisture content of 15±0.5% (wet basis). The brown rice was sealed in a fresh-keeping box with a specification of 200mm×140mm×60mm in a natural environment. Each box contained 500±50g of brown rice and was stored in a constant temperature environment of 15℃ (T1 group), 25℃ (T2 group), and 35℃ (T3 group). Samples were taken every other month, and three parallels were taken in each group to measure and observe the changes in the main quality indicators of brown rice at different temperatures during the 3-month storage period: moisture, fatty acid value, germination rate, and gelatinization characteristics. The thickness of the fresh-keeping sealing film is 8 filaments. The materials of the fresh-keeping box and the sealing film are high barrier materials of PP+PET (composite plastics containing polypropylene and polyester) and PP+PE+EVOH (composite film of polypropylene, polyethylene and ethylene-vinyl alcohol copolymer), respectively, to ensure that the moisture content of the brown rice and the humidity in the box during storage are not affected by the external environment. The experimental indicators were measured multiple times to obtain the average value and perform ANOVA analysis, and the Duncan test was used to examine the significance of data differences, the same below.

[0108] 3. Test results

[0109] 3.1 The test results of brown rice moisture are as follows Figure 7 shown.

[0110] The moisture changes of brown rice during storage at different temperatures for 3 months are as follows Figure 7 As shown. Figure 7 It can be seen that the moisture content of brown rice in group T1 did not change significantly during the 3-month storage period; the brown rice in group T2 did not change significantly during the 2-month storage period, but the moisture content of brown rice in the 3rd month was different from that in the first two months; the moisture content of brown rice in group T3 was different every month during the 1-3 months of storage. The reason should be that the lower storage temperature is not conducive to the respiration of brown rice grains, and the utilization of water inside the grains is limited, while the higher temperature can increase the enzyme activity in the grains and promote various biochemical reactions inside. In the biochemical reactions, the role of water molecules is significant, so the moisture content of brown rice shows certain fluctuations at higher storage temperatures. However, since this experiment uses sealed storage, the moisture content of grains in the fresh-keeping box will eventually reach equilibrium through adsorption and desorption, and there are individual differences in grains in the early stage of storage. Therefore, there is no statistically significant change in the moisture content of grains in each group, and the moisture content of brown rice in each group is basically stable at 15±0.5% (wb).

[0111] 3.2 Results of brown rice fatty acid value test

[0112] Figure 8 The figure shows the changes in fatty acid values ​​of brown rice at different temperatures during 3 months of storage. As can be seen from the figure, the fatty acid values ​​of brown rice in each group increased with the extension of storage time, which is consistent with existing research. In the first month of storage, the fatty acid values ​​of brown rice in each group were between 34.36 and 35.75 mg KOH / 100g, with no significant difference; however, from the second month of storage, the fatty acid value of group T1 differed from that of groups T2 and T3. At this time, the fatty acid value of group T1 was 39.64 mg KOH / 100g, while the values ​​of groups T2 and T3 were 41.96 mg KOH / 100g and 42.56 mg KOH / 100g, respectively; when brown rice was stored at different temperatures for 3 months, the fatty acid values ​​of each group showed significant differences. Specifically, the higher the temperature, the greater the fatty acid value. At this time, the fatty acid value of group T3 could reach 57.88 mg KOH / 100g, followed by group T2, while the lowest fatty acid value of group T1 was 49.46 mg KOH / 100g. The reason should be that the higher temperature increased the activity of enzymes such as lipase and lipoxygenase in the brown rice grains that participate in fat metabolism to produce free fatty acids, thereby promoting the production of free fatty acids. The level of free fatty acid value is often used as an important indicator to evaluate grain quality. An increase in grain fatty acid value often represents a deterioration in grain quality. This shows that low-temperature storage is beneficial to maintaining grain quality.

[0113] 3.3 The results of brown rice germination rate are as follows Fig. 9 shown.

[0114] The germination rate of brown rice stored at different temperatures for 3 months is as follows Fig. 9 As shown in the figure, the germination rate of brown rice in group T1 stored at 15°C decreased slightly during the three-month storage period, but remained basically unchanged, basically maintained between 72.5% and 75.5%; the germination rate of group T2 stored at 25°C decreased significantly with the extension of storage time, from 68.5% in the first month of storage to 11.5%; and the germination rate of group T3 stored at 35°C was 3% in the first month of storage, and the germination rate dropped to 0% in the next two months (not shown in the figure). High temperature increases the activity of various enzymes involved in biochemical reactions inside the brown rice grains, and biochemical reactions consume nutrients in the grain grains, which is not conducive to grain germination.

[0115] 3.4 The test results of brown rice gelatinization characteristics are shown in Table 4.

[0116] Table 4 Gelatinization characteristics of brown rice at different storage temperatures and for different storage times

[0117]

[0118]

[0119] Note: Different letters between different treatment groups in the same month represent significant differences.

[0120] The main component of brown rice is starch, and the starch gelatinization characteristic index can reflect its processing and edible quality to a certain extent. Peak viscosity reflects the ability of starch to bind water and indicates the thermal stability of starch; minimum viscosity is the minimum viscosity value of starch paste during cooling; attenuation value is the difference between peak viscosity and minimum viscosity, which is the most sensitive index among gelatinization indexes. The larger its value, the worse the high temperature stability and the easier it is for starch granules to break; final viscosity represents the gelation degree of cold paste, and the larger its value, the lower the viscosity of rice and the higher the hardness; the regeneration value represents the aging trend of starch cold paste, and the larger the regeneration value, the easier it is for rice to age and the worse the edible quality.

[0121] As can be seen from Table 4, with the increase of storage time and temperature, the peak viscosity, minimum viscosity, attenuation value and recovery value of brown rice all showed an upward trend, indicating that the edible quality of brown rice deteriorated, and there were obvious differences in the gelatinization characteristic data of each group within the same storage time, indicating that low temperature is conducive to the preservation of the edible quality of brown rice.

[0122] The following conclusions can be drawn from the above embodiments and comparative examples:

[0123] (1) Low temperature storage can effectively ensure the storage quality, grain activity and edible quality of brown rice;

[0124] (2) Through the key quality analysis of brown rice with added gas conditioning agent, it can be seen that the addition of 40g of gas conditioning agent can reduce the oxygen content of the inner packaging of 25Kg bagged brown rice to below 2%, and the fatty acid value and gelatinization characteristics of brown rice are significantly different from those of the control. The purpose of short-term storage of brown rice can be achieved by using PA / PE transparent packaging material with a single layer thickness of 12 threads as the inner packaging, kraft paper bags covered with plastic film as the outer packaging and adding a certain amount of gas conditioning agent.

[0125] (3) Small packages of rice were sealed in a laboratory controlled atmosphere environment and stored in a quasi-low temperature environment of 20°C and a normal temperature environment of 25°C for one year. By comparing the key quality indicators of rice during controlled atmosphere storage, such as germination rate, moisture, fatty acid value and gelatinization characteristics, with the relevant qualities of naturally stored rice without the addition of controlled atmosphere agents, it was found that controlled atmosphere sealed storage can maintain the moisture of rice to a certain extent, ensure the activity of rice grains and inhibit the deterioration of rice gelatinization characteristics, which has a certain promoting effect on rice quality assurance and grain freshness preservation.

[0126] (4) Compared with simple low-temperature storage, low-temperature controlled atmosphere storage has no significant difference in maintaining the moisture content of brown rice, but it has a more obvious effect on inhibiting the increase of the fatty acid value of brown rice and maintaining the activity of the grain, and can inhibit the deterioration of the edible quality of brown rice.

[0127] In general, controlled atmosphere storage and low-temperature controlled atmosphere storage, which reduce the oxygen content in the grain storage environment to below 2%, can play a positive role in maintaining the quality and freshness of rice.

[0128] References:

[0129] [1] Yao Yajing. Effects of low temperature, controlled atmosphere and UV-C treatment on storage quality of brown rice[D]. Tianjin Commercial University, 2021.

[0130] [2] Jiang Zhongzhu. Brown rice preservation theory and storage technology [J]. Grain Science and Technology and Economy, 2000(04):34-35.

[0131] [3]Tsuzuki W,Suzuki Y,Yamada S,et al.Effect of oxygen absorberonaccumulation of free fatty acids in brown rice and whole grain wheatduringstorage[J].LWT-Food Science andTechnology,2014,58(1):222-229.

[0132] [4] Tang Weimin, Zhang Xujing, Li Wenmin, et al. Storage technology and quality changes of brown rice [J]. Grain and Feed Industry, 2001(1):10-13.

[0133] [5] Wang Yufeng, Xia Jiqing, Sun Peiling. Development and application prospects of low temperature storage technology for brown rice[J]. Journal of Northeast Agricultural University, 2009, 40(04): 136-140.

[0134] [6] He Yukai, Yang Zhicheng, Zhang Zhengyan, et al. Research progress on the change and control of rice storage quality by controlled atmosphere technology[J]. Food Industry Science and Technology, 2021, 42(23): 377-384.

[0135] [7] Huang Hao, Wang Yi, Li Li, et al. Effects of low oxygen packaging on brown rice aging and quality[J]. Journal of the Chinese Cereals and Oils Association, 2021, 36(1): 8-13.

[0136] [8] National Technical Committee for Standardization of Cereals and Oils. GbT 20569-2006 Rules for Determining the Storage Quality of Rice[S]. Beijing: China Standards Press, 2006.

[0137] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for grain storage, comprising gas conditioning storage or controlled atmosphere storage, characterized in that: The gas conditioning agent storage comprises the following steps: placing the gas conditioning agent and food in a double-layer packaging device, and sealing and preserving them; The gas conditioning agent comprises the following components in percentage by weight: 75% to 85% iron powder, 1% to 4% activated carbon, 1% to 4% diatomaceous earth, 1% to 5% zeolite powder, 0.1% to 5% sulfate, 2% to 6% bicarbonate, 0.5% to 2% sulfite and 1% to 8% water, the sum of the components of the gas conditioning agent being 100%; The controlled atmosphere storage comprises the following steps: placing the grain in a fresh-keeping device containing controlled atmosphere gas, and sealing and preserving the grain; The gas for regulating the atmosphere includes nitrogen and oxygen, and the volume ratio of oxygen to nitrogen is 0-1:9-10.

2. The method according to claim 1, characterized in that During the storage of the gas conditioning agent, the weight ratio of the gas conditioning agent to the grain is (1-2):1250.

3. The method according to claim 1, characterized in that In the gas conditioning storage, the double-layer packaging device includes an inner layer packaging and an outer layer packaging, the material of the inner layer packaging is nylon or polyethylene plastic, and the material of the outer layer packaging is kraft paper or corrugated cardboard.

4. The method according to claim 3, characterized in that The double-layer packaging device includes a double-layer packaging bag or a double-layer packaging carton; The thickness of the plastic is 8 to 12 filaments.

5. The method according to claim 1, characterized in that In the controlled atmosphere storage, the weight of the grain and the volume of the controlled atmosphere gas are 1-25 (kg): 0.02-0.025 m 3 .

6. The method according to claim 1, characterized in that The fresh-keeping device comprises a fresh-keeping box, and the material of the fresh-keeping box comprises a high-barrier material.

7. The method according to claim 1, characterized in that The specifications of the atmosphere-adjusting agent storage and the atmosphere-controlled storage are 0.5kg to 25kg / packaging device, respectively.

8. The method according to claim 1, characterized in that The temperatures of the atmosphere conditioning agent storage and the atmosphere controlled storage are 15 to 20° C., respectively.

9. The method according to any one of claims 1 to 8, characterized in that: The food includes paddy and / or brown rice.

10. Use of the method according to any one of claims 1 to 9 in grain transportation.

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