Six-step fresh rice product capable of keeping fresh vitality and processing technology of six-step fresh rice product

Abstract

The invention relates to a six-step fresh rice product capable of keeping fresh vitality and a processing technology of the six-step fresh rice product. Specifically, the present invention provides a brown rice milling method and a rice processing method comprising the same, the milling method comprising a step of opening brown rice and a step of fine milling, the roughening meets the following requirements: after the roughening, the rice bran slices uncovered in the first fine grinding procedure pass through a 60-mesh sieve, and the mass of the rice bran slices intercepted by the sieve is 50-60% of the mass of all the uncovered rice bran slices; the fine grinding meets the condition that the sum of the grinding distribution ratios of all other fine grinding procedures except the last fine grinding procedure is 60-70%; and the grinding distribution ratio of the last process is 20-30%.

Description

Technical Field

[0001] This invention belongs to the field of grain processing, specifically relating to a six-step fresh rice product that maintains freshness and its processing technology. Background Technology

[0002] The freshness and deliciousness of rice are determined by two factors: firstly, the variety, as a good variety brings a delicious experience; and secondly, the techniques employed in rice cultivation, processing, storage, and transportation. For a given variety, good cultivation techniques, processing methods, and storage and transportation practices can guarantee the freshness and deliciousness of the rice.

[0003] In rice cultivation, variety improvement and breeding are crucial. However, achieving high yields and high-quality rice is a complex system engineering project involving an entire industry chain, with harvesting being an indispensable operational link. For double or triple harvests per year, to avoid affecting the timely sowing of the next season's rice, the rice needs to be harvested immediately after maturity, a process known as "rush harvesting," so there is rarely a problem of harvesting too late. However, there is a lack of scientific guidance on when to harvest. For single-harvest rice, harvesting usually begins when the yellow color of the husk fades to white, the stems begin to dry, and the grain moisture content is below 17%, that is, in the middle or late stages of the dry-ripe period.

[0004] The timely harvesting of rice is receiving increasing attention. However, there is no unified conclusion on how to scientifically conduct timely harvesting. Some scholars believe that the number of days after heading can be used to determine the appropriate harvesting time, but different varieties have different growth rates, and the growth status varies depending on the year and climate, thus this method has certain limitations. The number of days after heading may vary depending on the variety studied and the climatic conditions of that year. Therefore, some research methods have added changes in indicators such as accumulated temperature, yellowing rate, or rice moisture content during the rice growth process to determine the rice harvesting period. Among these, accumulated temperature and light are very important for rice growth, but the requirements for accumulated temperature are different for each rice variety, making recording relatively tedious. Furthermore, the moisture content of rice grains fluctuates with weather changes; for example, the moisture content of rice grains increases sharply after rain.

[0005] After harvesting, rice needs to be dried promptly and then stored. Currently, the most common drying equipment is continuous rapid drying, followed by storage at room temperature.

[0006] Before rice becomes finished rice, the raw grain needs to be processed, mainly including impurity removal, hulling, milling, color sorting, and other technological steps. Rice processing is a physical process. The milling precision is generally similar across different manufacturers. Some competitors have proposed the concept of "9% golden milling," while the Japanese industry has proposed the concept of "100% milling refinement." The grain industry standard "LS / T1231-2023 Rice Processing Technical Specification" requires that the whitening rate from the rough rice should not be less than 89.5%. In summary, the general milling precision results in a whitening rate of around 90%. Even if the final milling precision is similar, the milling process itself is crucial. Good milling process control leads to high rice yield, good quality, and good appearance; poor control results in low yield, poor quality, and a dull appearance. In the rice processing industry, the milling process is often adjusted based on experience. This approach lacks scientific control; some factories use whiteness meters to control the milling process, but whiteness is affected by the color of different rice varieties and chalkiness, resulting in some error.

[0007] Therefore, there is an urgent need in this field for a processing technology that keeps rice products fresh. Summary of the Invention

[0008] The present invention aims to achieve high rice yield, high milling rate, low breakage rate, high germination rate, high freshness, low broken rice rate, low temperature rise and low energy consumption during processing, and rice with higher aroma, higher taste value, better taste, better appearance quality, and better storage resistance.

[0009] Therefore, the first aspect of the present invention provides a method for milling brown rice, the method comprising a hulling and milling step, wherein the hulling satisfies the following conditions: the mass of the rice bran flakes removed in the first milling step after hulling and then passed through a 60-mesh sieve and retained by the sieve is in the range of 50-60% of all the removed rice bran flakes; and the milling satisfies the following conditions: the sum of the milling distribution ratios of all other milling steps except the last milling step is 60-70%, preferably 67±2%; and the milling distribution ratio of the last step is 20-30%, preferably 23±2%.

[0010] A second aspect of the present invention provides a rice processing technology, including harvesting, drying, balancing, storage, hulling and hulling separation, and milling steps as described in any embodiment herein.

[0011] In some embodiments, the harvesting includes harvesting rice with peroxidase, superoxide dismutase, catalase, and α-amylase activities within the following ranges: peroxidase activity of 250–800 U / g, superoxide dismutase activity of 5700–6500 U / g, catalase activity of 5.0–25.0 U / g, and α-amylase activity of 330–360 seconds.

[0012] In some embodiments, the harvesting includes harvesting rice with peroxidase, superoxide dismutase, catalase, and α-amylase activities within the following ranges: peroxidase activity of 350–700 U / g, superoxide dismutase activity of 5700–6000 U / g, catalase activity of 6.5–15.0 U / g, and α-amylase activity of 330–345 seconds.

[0013] In some embodiments, the rice variety is Daohuaxiang No. 2, and the harvesting includes selecting rice grains with enzyme activities of peroxidase, superoxide dismutase, catalase, and α-amylase within the following ranges for harvesting: peroxidase activity of 430-470 U / g, superoxide dismutase activity of 5850-5890 U / g, catalase activity of 13.0-14.0 U / g, and α-amylase activity of 330-340 seconds.

[0014] In some embodiments, the rice variety is Deyu 317, and the harvesting includes selecting rice with enzyme activities of peroxidase, superoxide dismutase, catalase, and α-amylase within the following ranges for harvesting: peroxidase activity of 350-370 U / g, superoxide dismutase activity of 5930-5970 U / g, catalase activity of 10.0-11.0 U / g, and α-amylase activity of 330-340 seconds.

[0015] In some embodiments, the rice variety is Nongjing 306, and the harvesting includes selecting rice with enzyme activities of peroxidase, superoxide dismutase, catalase, and α-amylase within the following ranges for harvesting: peroxidase activity of 610-620 U / g, superoxide dismutase activity of 5730-5770 U / g, catalase activity of 6.0-7.0 U / g, and α-amylase activity of 335-345 seconds.

[0016] In some embodiments, the drying includes tempering drying of freshly harvested rice, optionally followed by moisture equalization before tempering drying; wherein, if the moisture content of the freshly harvested rice is higher than 25 wt%, moisture equalization and tempering drying are performed sequentially; if the moisture content of the freshly harvested rice is less than or equal to 25 wt%, tempering drying is performed directly.

[0017] In some implementation schemes, a temperature 3–5°C lower than the drying temperature is used for moisture equalization, reducing the moisture gradient between grains to less than 2 percentage points.

[0018] In some implementation schemes, the tempering and drying process is divided into two stages. The goal of the first stage is to reduce the moisture content of the rice to 18% ± 0.5%, and the goal of the second stage is to further reduce the moisture content of the rice to 14.5% ± 1%. If the moisture content of the rice to be tempered is already below 18%, it will proceed directly to the second stage.

[0019] In some implementations, during the first stage, the drying temperature is controlled at 55–62°C, and the valley temperature is kept below 38°C.

[0020] In some implementations, in the second stage, the drying temperature is reduced by no more than 5°C compared to the first stage, preferably to 50-56°C, and the valley temperature is controlled below 38°C.

[0021] In some embodiments, during the drying process, when the moisture content of the rice is higher than 30 wt%, the water reduction rate is controlled to reduce the moisture by a maximum of 1.3 wt% per hour; when the moisture content of the rice is 22-30 wt%, the water reduction rate is controlled to reduce the moisture by a maximum of 1 wt% per hour; when the moisture content of the rice is 18-22 wt%, the water reduction rate is controlled to reduce the moisture by a maximum of 0.85 wt% per hour; and when the moisture content of the rice is 15-18 wt%, the water reduction rate is controlled to reduce the moisture by a maximum of 0.65 wt% per hour.

[0022] In some implementation schemes, the dried rice is transported to a dry grain silo to stand and equilibrate, and then stored after it has completely cooled down.

[0023] In some implementation plans, rice is stored at low temperatures after it is put into storage, meaning that the average grain temperature is kept below 15°C and the local maximum grain temperature does not exceed 20°C.

[0024] In some implementation schemes, rice quality is monitored during storage by germination rate, freshness, and rice enzyme activity. After storage, the rice meets the following criteria: germination rate ≥90%; freshness ≥85 points; and, using the enzyme activity at harvest as a control, the retention rates of peroxidase, superoxide dismutase, and catalase are all ≥80%, and the α-amylase activity, measured by falling number, is within 450 seconds.

[0025] A third aspect of the present invention provides a type of rice, wherein the rice, after milling, is placed in a constant temperature and humidity chamber at 35°C and 75% humidity for 6 weeks, and the decrease in taste is no higher than 21.00%, preferably no higher than 20.50%, wherein the taste is measured according to the "Sensory Evaluation Method for Cooked and Edible Quality of Rice and Grain in Grain and Oil Inspection" (GBT 15682-2008); and / or, the decrease in concentration of 2-acetylpyrrolline in the volatile flavor substances of the rice, after milling, is placed in a constant temperature and humidity chamber at 35°C and 75% humidity for 6 weeks, and the decrease is no higher than 48.00%, preferably no higher than 46.50%; and / or, the decrease in taste value, after milling, is placed in a constant temperature and humidity chamber at 35°C and 75% humidity for 6 weeks, and the decrease is no higher than 13.00%, preferably no higher than 12.00%.

[0026] In some implementations, the rice variety is Daohuaxiang No. 2.

[0027] In some embodiments, the reduction in the enzyme activities of POD, SOD, CAT, and α-amylase of the rice after milling and placing it in a constant temperature and humidity chamber at 35°C and 75% humidity for 6 weeks, compared with those of freshly milled rice, is no higher than 20.00%, 20.00%, 55.00%, and 25.00%, respectively.

[0028] In some embodiments, the enzyme activity reduction of the POD is not higher than 18.00%, more preferably not higher than 17.60%; and / or, the enzyme activity reduction of the SOD is not higher than 18.50%, more preferably not higher than 18.00%; and / or, the enzyme activity reduction of the CAT is not higher than 53.00%, preferably not higher than 51.50%; and / or, the enzyme activity reduction of the α-amylase is not higher than 24.90%.

[0029] A fourth aspect of the present invention provides rice processed using the method described in any embodiment herein.

[0030] The fifth aspect of the present invention provides a rice product containing rice as described in any embodiment herein.

[0031] The sixth aspect of the present invention provides cooked rice, or food containing rice, obtained by cooking rice or rice products as described in any embodiment herein.

[0032] The seventh aspect of the present invention provides the application of the milling method and / or processing technology described in any embodiment herein in one or more of the following aspects: (1) reducing the magnitude and rate of decrease in the enzyme activity of rice POD, SOD, CAT and α-amylase; (2) improving the freshness of rice; (3) reducing the increase in rice breakage rate; (4) reducing the germination rate of rice; (5) improving the anti-mold effect of rice; (6) improving the palatability, flavor and aroma of rice; (7) extending the shelf life of rice; (8) reducing the broken rice rate; (9) reducing the processing temperature rise of rice; and (10) slowing down the rate of quality decline of rice. Attached Figure Description

[0033] Figure 1 This is a diagram illustrating the degree of roughening. (a) indicates excessive roughening, and (b) indicates moderate roughening.

[0034] Figure 2 This is a comparison chart showing different drying effects. Detailed Implementation

[0035] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0036] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0037] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0038] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0039] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0040] In this article, the sum of the percentages of all components in the composition is 100%.

[0041] In this article, "rice" refers to both brown rice and regular rice.

[0042] In this article, "rice" refers to rice that has not had its husk removed.

[0043] In this article, "brown rice" refers to rice grains after the protective husk (rice husk) has been removed, including the bran layer, endosperm, and germ.

[0044] In this article, "rice" is also called germ rice, white rice, or polished white rice, referring to rice that has been processed to remove the bran layer.

[0045] In this article, rice can be japonica rice, such as round-grain rice with a grain length of less than 5.5 mm, or indica rice, such as long-grain rice with a grain length of more than 5.5 mm. The rice variety can be any variety well-known in the field, including but not limited to Daohuaxiang No. 2, Deyu 317, Nongjing 306, Yexiang Youlis, Xinfeng No. 6, Jihong No. 6 rice, super rice, Suijing 18, Longjing 31, Jihong 6, Yanfeng 47, Songjing 16, Longdun 1614, Longyang 16, Songjing 29, Zhongkefa 5, Zhongkefa 804, Tianlong 619, etc.; Daohuaxiang No. 2, Deyu 317, Yexiang Youlis, and Nongjing 306 are preferred.

[0046] In this article, "cracked grains" refers to transverse cracks in rice grains, and "cracked grain rate" refers to the percentage of cracked rice grains out of the total tested rice grains. Cracked grain rate is not an inherent physical characteristic of rice; it is an indicator used to assess the degree of grain breakage. Generally, a lower cracked grain rate indicates a smaller proportion of broken grains, resulting in better taste and quality of cooked rice. In this article, the cracked grain rate was determined according to the "GBT 21015-2023 Technical Specification for Rice Drying".

[0047] In this article, tempering refers to a buffering process (e.g., a gradient buffering process) that allows rice to adapt to sudden changes in drying temperature, ensuring a more uniform exchange of temperature and humidity within the rice grains, thereby reducing the impact of sudden environmental changes on the physicochemical properties and quality of the rice. In the tempering process described in this article, the tempering temperature is lower than the drying temperature.

[0048] In this article, balance refers to the uneven distribution of moisture in the grains after drying, and allowing the grains to stand for a period of time to allow the internal moisture to redistribute evenly.

[0049] In this article, rated capacity refers to the maximum amount of products that production equipment or a factory can produce or process within a certain time or planned cycle.

[0050] In this text, "in sequence" means that the processes or steps are carried out in the order of rice processing, and there are no other processes or steps between the sequentially performed processes or steps. For example, "in sequence, perform water equalization, drying and tempering" means that drying is performed after water equalization, and there are no other processes between the steps of water equalization and drying. Tempering is performed after drying, and there are no other processes between drying and tempering.

[0051] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0052] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0053] The inventors have discovered that by controlling the harvesting time through enzyme activity, the rice harvested in this way has the following characteristics: high yield and good quality; high taste value, low protein content, low amylose content, good taste, and higher aroma concentration; and better storage resistance and stronger antibacterial properties during storage.

[0054] Therefore, in some embodiments, this document provides a rice harvesting method, comprising harvesting rice with peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and α-amylase activities within the following ranges: peroxidase activity of 250–800 U / g, superoxide dismutase activity of 5700–6500 U / g, catalase activity of 5.0–25.0 U / g, and α-amylase activity of 330–360 seconds.

[0055] Preferably, the rice harvesting method described herein also includes the step of monitoring the enzyme activities of peroxidase, superoxide dismutase, catalase, and α-amylase in the rice to be harvested. Various methods well-known in the art can be used to test the enzyme activities of rice peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and α-amylase. In some embodiments, the enzyme activity of rice POD can be detected using the guaiacol method disclosed in the literature; the enzyme activity of CAT can be detected using the ammonium molybdate method disclosed in the literature; the enzyme activity of SOD can be detected using the hydroxylamine method disclosed in the literature; and the enzyme activity of α-amylase can be detected using the Hagberg-Perten method (GB / T 10361-2008) for the determination of falling values ​​of wheat, rye and their flour, durum wheat and its coarse flour. α-amylase activity is expressed as a falling value; the higher the falling value, the lower the enzyme activity.

[0056] In some embodiments, the preferred enzyme activity of the peroxidase is 350–700 U / g. In some embodiments, the preferred enzyme activity of the superoxide dismutase is 5700–6000 U / g. In some embodiments, the preferred enzyme activity of the catalase is 6.0–15.0 U / g. In some embodiments, the preferred enzyme activity of the α-amylase is 330–345 seconds.

[0057] In some implementations, the monitoring steps described above begin a certain period after rice heading, for example, 40 days after heading in northern China and 35 days after heading in southern China. Monitoring can be conducted periodically, for example, every 1–10 days, 1–5 days, or 3–5 days. It should be understood that when the levels of POD, SOD, CAT, and α-amylase are detected to be close to or partially within the ranges described herein, the monitoring frequency can be increased, for example, from once every 3–5 days to once daily. Harvesting can proceed when the levels of POD, SOD, CAT, and α-amylase in the rice grains fall within the scope of this application, especially within the preferred ranges described above. A five-point sampling method can be used for sampling, and the above-described tests can be performed.

[0058] Freshly harvested rice respires rapidly and heats up easily when piled up, requiring timely drying to reduce its moisture content—a process known as "moistening" in the rice processing industry. Preferably, drying of the rice begins within 24 hours of harvesting.

[0059] The inventors also discovered that conventional drying methods involve continuous drying, which directly dries rice from high moisture content to a target moisture content (e.g., 15.0 ± 0.5%). Although this method is highly efficient, the resulting rice is of poor quality, has a weak aroma, and is prone to cracking. However, by using tempering drying to dry freshly harvested rice with high moisture content, the flavor, storage life, and antibacterial properties of the rice can be further improved.

[0060] Therefore, in some embodiments, the present invention provides a rice drying method, which includes a tempering drying step. In some embodiments, if the moisture content of the harvested fresh rice is greater than 25 wt%, it is preferable to perform moisture equalization (i.e., "moisture equalization") before tempering drying to ensure uniform moisture reduction in individual rice grains. Specifically, moisture equalization can be performed at a temperature about 3-5°C lower than the drying temperature (e.g., air temperature) (e.g., at about 45-55°C or about 46-52°C), allowing rice grains with different moisture levels to come into full contact, equalizing moisture between grains, and reducing the moisture gradient between grains to within 2 percentage points. If the moisture content of the harvested fresh rice is moderate (e.g., less than or equal to 25 wt%), tempering drying can be performed directly. Methods for detecting rice moisture content are well known in the art, and multiple measurements of the harvested rice can be taken and averaged (e.g., the five-point method). It should be understood that during moisture equalization or tempering drying, rice moisture content can be monitored in real time, and if the moisture content is met, the next stage can be directly carried out.

[0061] In this paper, the tempering and drying process can be divided into two stages. The goal of the first stage is to reduce the moisture content of the rice to 18% ± 0.5%, and the goal of the second stage is to further reduce the moisture content of the rice to 14.5% ± 1%. If the moisture content of the raw material is already below 18%, it can directly proceed to the second stage.

[0062] In the first stage, the drying (moistening) temperature can be controlled at approximately 55–62℃. Since the large amount of water evaporated will take away heat, the grain temperature can be maintained at a low level below 38℃ to preserve the good activity of the rice. The second stage begins when the rice moisture content drops to 18% ± 0.5%.

[0063] After a large amount of free water has been removed, the drying temperature is lowered by up to 5°C, such as 3-5°C, i.e., controlled at approximately 50-56°C, to slow down the rate of moisture removal and initiate the second stage of tempering drying. During this stage, the grain temperature is still controlled below 38°C to preserve the rice's excellent aroma and flavor to the greatest extent possible during the drying process. The final moisture content, which is the final moisture content of the raw material, is controlled at 14.5% ± 1%.

[0064] Preferably, precipitation rate is used to control moisture equalization and tempering drying. In this document, precipitation rate refers to the proportion of water reduction per kilogram of material per hour due to evaporation or drying relative to the total moisture content per kilogram of material. In some embodiments, the operating conditions such as temperature and wind speed for moisture equalization, drying, and / or tempering are adjusted by monitoring the rice precipitation rate. For example, when the rice moisture content is greater than 30%, the precipitation rate is controlled to reduce moisture by a maximum of 1.3 wt% per hour; when the rice moisture content is 22–30 wt%, the precipitation rate is controlled to reduce moisture by a maximum of 1 wt% per hour; when the rice moisture content is 18–22 wt%, the precipitation rate is controlled to reduce moisture by a maximum of 0.85 wt% per hour; and when the rice moisture content is 15–18 wt%, the precipitation rate is controlled to reduce moisture by a maximum of 0.65 wt% per hour.

[0065] Temper drying can be performed using commonly used drying equipment in this field, such as a dryer. Drying is typically achieved using air at the indicated temperature.

[0066] During the drying process, there are no special restrictions on the duration of water equalization and tempering drying, as long as the moisture content of the rice is controlled within the range specified above. At the same time, it is preferable to control the rate of water precipitation as described above.

[0067] It should be understood that a large amount of moisture evaporates from the rice during the drying process, and its temperature decreases. Therefore, in order to maintain the activity of the rice, the temperature of the rice should be controlled not to exceed 38°C. Preferably, the temperature of the rice during the drying process should be controlled at 35-38°C.

[0068] Preferably, after drying, the retention rates of the three enzymes peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) in rice (based on enzyme activity at harvest) are ≥90%, while the increase in the number of seconds for α-amylase, based on the falling value (based on enzyme activity at harvest), is ≤30s.

[0069] In a preferred embodiment, after drying, the peroxidase (POD) activity in the rice is 200–680 U / g, the superoxide dismutase (SOD) activity is 5300–5900 U / g, the catalase (CAT) activity is 5.0–23.0 U / g, and the α-amylase activity is 340–360 seconds. In some embodiments, after drying, the peroxidase (POD) activity in rice (such as Daohuaxiang No. 2) is 430–440 U / g, the superoxide dismutase (SOD) activity is 5300–5600 U / g, the catalase (CAT) activity is 12.0–13.0 U / g, and the α-amylase activity is 340–350 seconds. In some implementations, after drying, the peroxidase (POD) activity in rice (such as *Eriocaulon buergerianum*) is 360–380 U / g, the superoxide dismutase (SOD) activity is 5300–5600 U / g, the catalase (CAT) activity is 5.0–6.0 U / g, and the α-amylase activity is 370–410 U / g.

[0070] This article describes how to control drying conditions by selectively applying uniform moisture and slow tempering drying, as well as selectively applying enzyme activity, to obtain rice with a richer aroma, less breakage, and higher germination rate, germination index, and vigor index.

[0071] Even after drying, the internal moisture of the rice grains remains unevenly distributed, preventing direct processing or storage. The rice needs to be allowed to equilibrate (remain still) before further processing to redistribute the moisture evenly. In some implementation schemes, this equilibration period can exceed 48 hours. There are no specific environmental restrictions for equilibration; the dried rice can be transported to a dry grain silo and allowed to cool completely before storage.

[0072] After balancing, the rice is stored in warehouses. In this study, low-temperature storage is preferred after the rice is stored, meaning the average grain temperature is maintained at 15℃ or below, with the highest local temperature not exceeding 20℃. During storage, the grain pile is kept at a low temperature, and the grain temperature is monitored and analyzed at least once a week. When the grain pile temperature exceeds the low-temperature standard (i.e., above 15℃), the grain temperature is monitored and analyzed at least once every three days, and measures are taken within 15 days to lower the grain temperature to the low-temperature standard. Different storage methods can be selected for different seasons. For example, ventilation and cold storage in winter, heat insulation in spring, and air conditioning temperature control in summer and autumn. When the temperature is higher than the ideal low-temperature storage temperature (e.g., in summer), a grain cooling system can be used to supplement cold air, introducing fresh, dry, and cold air to replace the humid and hot gases in the grain pile, regulating humidity and controlling mold and microorganisms, keeping the grain pile in a fresh, dry, and low-temperature preservation storage state.

[0073] This paper monitors rice quality during storage by measuring germination rate, freshness, and rice enzyme activity. After storage, the rice must meet the following criteria: germination rate ≥90%, freshness ≥85 points, and enzyme activity retention rates of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) ≥80% (using harvest activity as a control), while α-amylase activity (measured by falling weight) must be controlled within 450 seconds. During storage, these indicators can be monitored periodically based on factors such as regional temperature; rice outside these ranges is discarded. For example, in northern regions, monitoring is conducted every two months from the time the new grain enters storage until April of the following year, and monthly from April to September; while in southern regions, monthly monitoring is conducted throughout the year.

[0074] Typically, rice can be screened before storage to reduce impurities. Screening includes steps such as impurity removal, stone removal, and magnetic separation. This article does not impose special restrictions on the screening process, only requiring that the quality of the rice be guaranteed, with the total impurities in the rice ≤1.0% based on the total weight of the rice entering storage.

[0075] This article describes how low-temperature storage can result in higher retention of rice enzyme activity, better rice freshness, and improved taste.

[0076] In a preferred embodiment, after low-temperature storage, the peroxidase (POD) activity in rice is 380–400 U / g, the superoxide dismutase (SOD) activity is 4700–4900 U / g, the catalase (CAT) activity is 10.0–12.5 U / g, and the α-amylase activity is 370–390 seconds. When it is necessary to sell the rice, the paddy can be separated into hulled and bran grains. Hulling is to remove the husk from the paddy. This can be achieved by squeezing and tearing the paddy between rollers. Bran grain separation refers to separating the brown rice and paddy from the bran grain mixture. Bran grain separation can be performed using methods commonly used in the art, such as shaking, and bran grain separators commonly used in the art can be selected to complete the bran grain separation.

[0077] Brown rice, obtained from hulling, requires further milling to produce white rice. The inventors discovered that by optimizing the milling ratio or degree of milling, low-temperature milling (temperature rise less than 20°C) can be achieved, resulting in less breakage (less than 2%), lower rice temperature, higher enzyme activity, richer aroma, and a higher overall taste value for the cooked rice. In this article, breakage rate refers to the increase in the proportion of broken rice compared to the initial milling state.

[0078] Therefore, this invention provides a method for milling brown rice, which includes hulling and milling. Milling using the method of this invention can reduce the broken rice rate, reduce the temperature rise of the rice after milling, increase the enzyme activity of the rice after milling, and improve the flavor and / or eating value of the rice after milling. This method includes controlling the degree of processing of the brown rice at each step of the milling process by using a milling distribution ratio; that is, the method includes controlling the particle size and / or content of the rice bran flakes removed during milling and the milling distribution ratio. In this document, the milling distribution ratio is the percentage of the mass of rice bran removed during a certain milling step in the total mass of the brown rice.

[0079] Hulling is the first step in milling, and its purpose is to create scratches on the surface of the bran layer of brown rice. If the density of scratches on the surface of the brown rice from the hulling process is too high, it is considered over-hulling (e.g., ...). Figure 1 (a) This process causes significant damage to the endosperm, and rice bran flakes with excessively fine openings are difficult to peel off in subsequent processes. If the scratch density is too low, multiple scouring processes are still required, wasting time and production capacity. The inventors discovered that by controlling the rice bran flakes produced during scouring as follows, appropriate scouring can be achieved, making it easier to peel off the rice bran flakes, reducing time and increasing production capacity: the proportion of rice bran flakes retained by the sieve after the first scouring and milling process, after passing through a 60-mesh sieve, should be in the range of 50-60% of all peeled rice bran flakes. Scouring can be performed using a sand roller. It should be understood that those skilled in the art can easily determine the scouring process based on the parameters of the equipment used and the type of brown rice to be milled, thereby producing rice bran flakes that meet the above requirements. For example, the pressure current value of the sand roller can be set to 75±10A, and the flow rate can be set to 5-7 tons / hour.

[0080] In this paper, after hulling, fine milling is performed to remove the bran flakes from the surface of the hulled rice, obtaining white rice with the outer bran removed. The first fine milling (i.e., the second milling process) is generally insufficient to completely remove the bran layer from the surface of the hulled rice. Therefore, a second, third, or even more fine milling processes (i.e., the third, fourth, etc. milling processes) are performed after the second milling process to completely remove the bran from the surface of the hulled rice. The inventors have discovered that controlling the milling ratio as follows can reduce the rice breakage rate, reduce the temperature rise of the rice after milling, increase the enzyme activity of the rice after milling, and improve the flavor and / or palatability of the rice after milling: the sum of the milling ratios for all other milling processes except the first and last processes is 60–70%, preferably 65 ± 2%; the milling ratio for the last process is 20–30%, preferably 25 ± 2%. Fine milling can be carried out using sand rollers and / or iron rollers, depending on the actual degree of milling and the requirements for the finished rice.

[0081] Exemplary milling processes may include two sand rollers and two iron rollers, or three sand rollers and one iron roller. Round-grain rice often uses a combination of sand rollers and iron rollers, such as one sand roller and two iron rollers; long-grain rice often uses a sand roller process, and iron rollers may be added depending on the actual situation.

[0082] The degree of rice milling is typically controlled by the flow rate, pressure, and different combinations of rice milling machines. Therefore, those skilled in the art can adjust the operating equipment of each rice milling machine to meet the requirements of the rice bran flake particle size and / or content, as well as the milling distribution ratio, as described in the method of this invention, thereby achieving the technical effects of this invention. In an exemplary implementation, a Satake Machinery VTA10AB type sand roller rice milling machine (sand grade 40#) and a Satake VBF10A type iron roller are used to mill rice. For example, the flow rate of round-grain rice is controlled at 5 to 7 tons / hour. In the one-sand-two-iron process, the steps are sand roller, iron roller, and iron roller in sequence, and the pressure and current values ​​can be 75±10A, 110±10A, and 90±10A, respectively. In the one-sand-three-iron process, the steps are sand roller, iron roller, iron roller, and iron roller in sequence, and the pressure and current values ​​can be 75±10A, 70±10A, 70±10A, and 70±10A, respectively. In the two-sand-one-iron process, the steps are sand roller, sand roller, and iron roller in sequence, and the pressure and current values ​​can be 75±10A, 80±10A, and 90±10A, respectively. For example, the flow rate control for long-grain rice is 5-7 tons / hour. In the two-sand, two-iron process, the steps are sand roller, sand roller, iron roller, and iron roller in sequence, with pressure and current values ​​of 75±10A, 75±10A, 85±10A, and 85±10A respectively. In the three-sand, one-iron process, the steps are sand roller, sand roller, sand roller, and iron roller in sequence, with pressure and current values ​​of 75±10A, 70±10A, 80±10A, and 80±10A respectively. It should be understood that rice milling machines of different models, manufacturers, and rated capacities have similar grinding principles, and those skilled in the art can choose according to the actual situation. For example, the flow rate of the rice milling machine can be controlled according to the size of the feed inlet or the speed control of the frequency converter, generally with a dial of 6-10; the pressure and current values ​​can be controlled by adjusting the weight on the rice milling machine.

[0083] In some implementations, the grinding process is three sand rollers and one iron roller. The sand roller is model Satake VTA10AB-C with sand grade 30#, and the iron roller is model Satake VBF10A-C. The pressure and current values ​​for each process are 72A, 65A, 70A, and 93A, respectively. After the first sand roller roughening, the content of rice bran flakes with a particle size greater than 60 mesh is 50-55% based on the total weight of the rice bran flakes. The grinding distribution ratio from the second to the third sand roller is 66-67%, and the grinding distribution ratio of the last iron roller is 24-25%.

[0084] It should be understood that when milling equipment is operating at full capacity, the machine temperature becomes too high, and the material rises significantly during the milling process, ultimately affecting the quality of the finished rice, such as resulting in a high rate of broken rice. Therefore, the flow rate or feed rate of rice processed by milling equipment is usually controlled to be below 85% of the rated capacity of the equipment.

[0085] This invention does not impose any particular limitations on polishing. The amount of water added during the polishing stage can be adjusted to achieve a suitable polishing effect. The amount of water added during the polishing process can be controlled according to actual needs, for example, to 20L / H or more.

[0086] After processing, rice is typically preserved using low-oxygen methods such as vacuuming, gas filling, or deoxidizing agents, and packaged immediately after milling. The storage of finished rice can be chosen based on actual inventory or sales needs. In principle, finished rice should not be stored in the factory for more than 7 days in a cool, dry warehouse away from direct sunlight. If storage exceeds 7 days, the temperature of the area or space where the finished rice is stored should generally not exceed 25℃; for example, the storage temperature for japonica rice should not exceed 22℃, and the storage temperature for indica rice should not exceed 25℃.

[0087] The rice prepared using the harvesting, drying, and milling methods of the present invention can improve rice quality, extend the shelf life of finished rice, and slow down the rate of quality degradation of finished rice (e.g., enzyme activity and sensory evaluation). Therefore, in some embodiments, the present invention also provides a rice processing method comprising the steps of harvesting, drying, balancing, storing, separating ridges and patina, and milling as described in any embodiment herein.

[0088] Therefore, in some embodiments, the present invention provides a type of rice characterized by: (1) a taste reduction of no more than 21.00%, preferably no more than 20.50%, measured after milling and placing in a constant temperature and humidity chamber at 35°C and 75% humidity for 6 weeks; wherein the taste is measured according to the "Sensory Evaluation Method for Cooking and Eating Quality of Rice and Grain in Grain and Oil Inspection" (GBT 15682-2008); (2) an aroma reduction of no more than 48.00%, preferably no more than 46.50%, measured after milling and placing in a constant temperature and humidity chamber at 35°C and 75% humidity for 6 weeks; wherein the aroma value refers to the relative mass fraction (ppb) of 2-acetylpyrrolline in the total flavor substances of white rice; and / or (3) an eating value reduction of no more than 13.00%, preferably no more than 12.00%, measured after milling and placing in a constant temperature and humidity chamber at 35°C and 75% humidity for 6 weeks; wherein the eating value is measured according to the STA1B rice eating value meter.

[0089] In some embodiments, the present invention provides a type of rice prepared by milling brown rice, characterized in that (4) the enzyme activities of POD, SOD, CAT and α-amylase measured after milling and placing in a constant temperature and humidity chamber at 35°C and 75% humidity for 6 weeks are not higher than the enzyme activities of POD, SOD, CAT and α-amylase measured within 24 hours after milling by no more than 20.00%, 20.00%, 55.00% and 25.00%, respectively. Preferably, the enzyme activity reduction of POD is not higher than 18.00%, more preferably not higher than 17.60%; preferably, the enzyme activity reduction of SOD is not higher than 18.50%, more preferably not higher than 18.00%; preferably, the enzyme activity reduction of CAT is not higher than 53.00%, more preferably not higher than 51.50%; preferably, the enzyme activity reduction of α-amylase is not higher than 24.90%.

[0090] In some implementations, the rice described herein has the features described in items (1), (2), (3) and (4) above.

[0091] In some embodiments, after milling, the rice described herein exhibits peroxidase (POD) activity of 290–390 U / g, superoxide dismutase (SOD) activity of 4800–5800 U / g, catalase (CAT) activity of 8.0–12.0 U / g, and α-amylase activity of 360–390 seconds. Preferably, the rice variety is Deyu 317, and after milling, the rice exhibits peroxidase (POD) activity of 290–300 U / g, superoxide dismutase (SOD) activity of 5770–5790 U / g, catalase (CAT) activity of 8.3–8.7 U / g, and α-amylase activity of 380–390 seconds. Preferably, the rice variety is Daohuaxiang No. 2, and after milling, the rice has a peroxidase (POD) activity of 380-385 U / g, a superoxide dismutase (SOD) activity of 4870-4880 U / g, a catalase (CAT) activity of 11.0-12.0 U / g, and an α-amylase activity of 360-370 seconds.

[0092] In some embodiments, the rice described herein is prepared using the methods and / or processing techniques described in any embodiment of this invention. In some embodiments, the present invention also provides paddy rice prepared using the paddy rice harvesting method described in any embodiment of this invention.

[0093] In some embodiments, the present invention also provides the application of milling methods and / or rice processing techniques as described in any embodiment herein in improving the quality of paddy and rice. Preferably, the improvement of paddy quality includes reducing or slowing down the magnitude or rate of enzyme activity reduction, improving freshness, reducing the increase in breakage rate, reducing germination rate, and / or improving anti-mold effect; the improvement of rice quality includes reducing or slowing down the magnitude or rate of enzyme activity reduction, taste value, flavor and aroma, extending the shelf life of rice, reducing the rice breakage rate, reducing the rice processing temperature rise, and / or slowing down the decline in the quality of finished rice.

[0094] In some embodiments, the invention also includes the application of the milling method and / or rice processing technology as described herein in one or more of the following:

[0095] (1) Reduce the amylopectin content of rice or paddy;

[0096] (2) Reduce the protein content of rice or paddy;

[0097] (3) Reduce or slow down the decrease in the activity of rice or paddy amylase.

[0098] (4) Reduce or slow down the decrease in the activity of peroxidase in rice or paddy.

[0099] (5) Reduce or slow down the decrease in the activity of superoxide dismutase in rice or paddy; and

[0100] (6) Reduce or slow down the decrease in catalase activity in rice or paddy.

[0101] In some embodiments, the present invention also provides cooked rice, which is obtained by cooking rice using the rice described in any of the embodiments herein. In some embodiments, the present invention also provides a food product containing the rice described herein. This food product may be, for example, a rice ball.

[0102] The present invention has the following beneficial effects:

[0103] 1) By controlling the optimal harvesting time through enzyme activity, the resulting rice has a high yield and good quality; it has a high eating value, low protein content, low amylose content, good taste, and higher aroma concentration; and it is more resistant to storage and has stronger antibacterial properties during storage.

[0104] 2) By selecting uniform water content, slow tempering drying, and enzyme activity to control the drying conditions, the resulting rice has a richer aroma, less breakage, and higher germination rate, germination index, and vitality index.

[0105] 3) Low-temperature storage results in higher enzyme activity retention, stronger antibacterial properties, better rice freshness, and superior taste.

[0106] 4) By distributing the milling pressure appropriately, the rice is milled at a lower temperature, resulting in lower rice temperature, less energy consumption, higher enzyme activity, richer aroma, and higher taste value.

[0107] The present invention will be further described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and not intended to limit the scope of the invention. The methods and reagents used in the embodiments are conventional methods and reagents in the art, unless otherwise stated. In the embodiments of the present invention, dried paddy rice refers to paddy rice after drying equilibrium, and the equilibrium paddy rice or sample also refers to paddy rice after drying equilibrium; except for the embodiments in Embodiment 4, the other embodiments all use the LTJM-160 high-speed rice polishing machine to prepare white rice.

[0108] Detection methods

[0109] 1. Preparation of small samples before testing (rice for sample testing)

[0110] A random sample of rice (approximately 500g) was taken and prepared into a small rice sample using the following steps. This sample was used to detect various enzyme activities, palatability values, amylose content, protein content, freshness, taste, and aroma.

[0111] Small-scale dryer drying: Low-temperature circulating drying is carried out using a drum-type hot air dryer (model HJ-1000, Gongyi Hengji Machinery Co., Ltd., Gongyi, Henan). The specific drying parameters are as follows: The weight of wet grains fed each time is 3±0.5kg, the drying temperature is set at 50℃, and the rice is collected when the moisture content drops to 14.5±1℃ to obtain dried rice.

[0112] Experimental rice milling: 150g of paddy rice was used to prepare rice samples using a LTJM-160 high-speed rice milling machine. The control parameters were set to level 4, and milling lasted 40 seconds. The rice was then sieved for 60 seconds on each side using a 2.0mm vibrating sieve, and the material remaining on the sieve was collected to obtain the rice samples. For samples that had already been dried in a large drying tower in the examples and comparative examples, the rice was directly milled using the experimental rice milling machine to obtain rice samples for parameter testing. For rice samples that had already been milled in the examples and comparative examples, their parameters were directly measured without requiring further drying and milling.

[0113] 2. Determination of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD)

[0114] The white rice prepared by the method described in point 1 above was subjected to the determination of three enzyme activities. Among them, the detection of POD was carried out according to the method disclosed by Gu Yun (“The Influence of Hydraulic Iron Ore on the Growth of Maize and Rice and the Activity of Antioxidant Enzymes”, Journal of Nanjing Agricultural University, 2018, 41(5): 860-866, the same below) (guaiacol method), and the POD kit provided by Nanjing Jiancheng Biotechnology Co., Ltd. was used for determination, and each sample was tested in parallel 3 times; the detection of CAT was carried out according to the method disclosed by Gu Yun (ammonium molybdate method), and the CAT kit provided by Nanjing Jiancheng Biotechnology Co., Ltd. was used for determination, and each sample was tested in parallel 3 times; the detection of superoxide dismutase (SOD) was carried out according to the method disclosed by Gu Yun (hydroxylamine method), and the SOD kit provided by Nanjing Jiancheng Biotechnology Co., Ltd. was used for determination, and each sample was tested in parallel 3 times.

[0115] 3. Assay for α-amylase

[0116] The amylase activity of white rice prepared by the method described in point 1 above was determined in seconds according to GB / T 10361-2008 Wheat, Rye and their Flour, Durham and its Coarse Flour - Determination of Falling Value - Hagberg-Perten Method.

[0117] 4. Determination of protein content

[0118] The protein content of white rice prepared by the method described in point 1 above was determined according to GB-T5511-2008 Determination of Nitrogen Content and Calculation of Crude Protein Content in Cereals and Legumes (Kjeldahl Method).

[0119] 5. Determination of amylose content

[0120] The amylose content of white rice prepared by the method described in point 1 above was determined according to GB / T 15683-2008, "Determination of Amylose Content in Rice".

[0121] 6. Determination of the flavor of cooked rice

[0122] The taste of cooked rice prepared by the method described in point 1 above was determined according to the "Sensory Evaluation Method for Cooking and Eating Quality of Rice and Paddy" in GB / T 15682-2008 Grain and Oil Inspection. The full score for taste is 25 points.

[0123] 7. Measurement of the increase in waist collapse rate

[0124] The drying process shall be carried out in accordance with the "GBT 21015-2023 Technical Specification for Rice Drying". The cracking rate is the percentage difference between the cracking rate of rice before and after drying. Here, drying refers to the large-scale drying tower (including continuous drying and low-temperature tempering) described in the various embodiments and comparative examples.

[0125] 8. Determination of grinding distribution ratio

[0126] Whole brown rice and whole polished rice are randomly selected from a milling machine at a certain stage. 1000 grains of whole brown rice are fed into the machine and weighed (M0), and 1000 grains of whole polished rice are discharged from the machine and weighed (M). X The mass of rice bran removed in this process is the mass difference ΔM between the rice grains entering and leaving the machine in this process. For example, the mass of rice bran removed in the first process is ΔM1 = M0 - M1, and the mass of rice bran removed in the second process is ΔM2 = M1 - M2. The grinding distribution ratio is calculated according to the following formula:

[0127]

[0128] 9. Determination of the aroma of white rice

[0129] 1) Sample preparation of fragrant rice: Quickly weigh 2.00g of rice, the internal standard is 10mg / kg 2-methyl-3-heptanone, place it in a 20mL screw-top headspace bottle, seal it, and wait for the sample to be tested.

[0130] 2) Sample preparation of fragrant rice: Quickly weigh 2.00g of rice, add 2.6g of water, the internal standard is 10mg / kg 2-methyl-3-heptanone, put it in a 20mL screw-top headspace bottle, seal it, put it in a rice cooker, and wait for the sample to be tested after cooking.

[0131] 3) HS-SPME conditions: Use a 50 / 30μm DVB / CAR / PDMS fiber head, age at 80℃ for 10 min, perform headspace extraction for 40 min, desorb at the GC-MS injection port for 5 min, and then perform GC-MS analysis;

[0132] 4) GC conditions: The column was HP-5MS (60m×0.25mm×0.25μm); the injection port temperature was 250℃; the temperature program was as follows: column temperature 40℃, hold for 1 min, increase to 250℃ at 5℃ / min, hold for 5 min, then run at 280℃ and hold for 2 min; the carrier gas was high-purity He, and the carrier gas flow rate was 1.0 mL / min; splitless injection was used.

[0133] 5) MS conditions: EI source; ion source temperature 230℃; quadrupole temperature 150℃; electron energy 70eV; transfer line temperature 280℃; mass range 35~350amu;

[0134] 6) Identification and content of volatile substances: The relative mass fraction (ppb) of 2-acetylpyrrolidine (2-AP) was determined by searching the NIST17 standard mass spectrum and comparing each peak in the total ion chromatogram with the data of the mass spectrometry computer system. This relative mass fraction (ppb) was determined by the internal standard semi-quantitative method.

[0135] 10. Determination of taste value

[0136] Rice was cooked at a rice-to-water ratio of 1:1.3 and cooled at room temperature for 2 hours before being tested for its palatability. The equipment used was a STA1B rice palatability meter, operated according to the instruction manual. The palatability value was directly displayed by the device.

[0137] 11. Determination of Freshness Value

[0138] The freshness value of rice raw materials was determined in accordance with "LS / T 6118-2017 Grain and Oil Inspection: Determination and Judgment of Freshness of Rice".

[0139] 12. Determination of rice germination rate

[0140] Germination test: Seeds were disinfected with 0.5% NaClO solution, thoroughly rinsed with clean water, and placed on germination boxes lined with two layers of damp gauze. Each box contained 100 seeds. The seeds were placed in a greenhouse at 20-30℃ with a light exposure of 16 hours followed by 8 hours of darkness. Germination was defined as a radicle length of 1 mm. The number of germinated seeds was recorded daily, and the germination rate was calculated on day 14. On the day the germination rate was calculated, 20 seedlings were randomly selected, and their fresh weight was measured. The seedlings were then placed at 80℃ for 2 hours, and their dry weight was measured.

[0141] Germination rate: Y = M1 / 100

[0142] Germination index: GI = ∑Gt / Dt

[0143] Vitality Index: VI = GI * S

[0144] In the formula, M1 is the number of germinated seeds, Gt is the number of germinated seeds on day t, Dt is the number of germination days, and S is the dry weight of 20 seedlings.

[0145] 13. Detection of broken rice rate

[0146] The broken rice rate of finished white rice on the production line is tested according to GB / T 5503-2009 Grain and Oil Inspection Broken Rice Test Method.

[0147] 14. Temperature rise calculation

[0148] The temperature rise is calculated according to the "LS / T1231-2023 Rice Processing Technical Specification", where temperature rise = rice temperature exiting the machine - brown rice temperature entering the machine.

[0149] 15. Moisture content determination

[0150] Perform in accordance with GB 5009.3-2016 National Food Safety Standard - Determination of Moisture in Food.

[0151] 16. Rice planting locations

[0152] Daohuaxiang No. 2, Wuchang City, Heilongjiang Province; Deyu 317, Changchun City, Jilin Province; Nongjing 306, Jiutai City, Jilin Province; Yexiang Youlis, Wannian County, Jiangxi Province.

[0153] 17. Rice mold colony count

[0154] Referencing GB 4789.15-2016 National Food Safety Standard: Microbiological Examination of Food - Counting of Molds and Yeasts

[0155] 18. Yield per mu

[0156] The conventional calculation method in this field is used to calculate the rice yield per acre.

[0157] Example 1: Rice quality under different harvesting conditions

[0158] Example 1

[0159] Daohuaxiang No. 2 rice was harvested 68 days after heading. The moisture content of fresh rice was tested. The contents of POD, SOD, CAT and α-amylase were measured according to the small dryer and experimental rice milling machine milling methods described in Section 1 of the "Detection Methods" section. The results are shown in Table 1.

[0160] Freshly harvested rice is subjected to slow tempering and drying, with the wind temperature controlled at 55℃, the rice temperature controlled at 38℃, and the water precipitation rate controlled at 0.85% / h. After the rice moisture content drops to 18.5%, the wind temperature is controlled at 50℃, and the water precipitation rate is controlled at 0.65% / h, until the rice moisture content is 15±0.5%.

[0161] After drying and equilibration for 48 hours, four parallel samples were taken from the discharge port of the drying tower, each weighing 1 kg. The moisture content of the equilibrated paddy was 15.3%. The parameters of the equilibrated paddy were tested according to the method described above, and the yield per mu (unit of land area) was calculated. The results are shown in Table 2. The parameters of the rice samples obtained by the rice milling machine described in Section 1 of the "Test Methods" section are shown in Table 3.

[0162] Comparative Example 1

[0163] Another batch of Daohuaxiang No. 2 rice, harvested 79 days after heading, was tested for moisture content. The contents of POD, SOD, CAT and α-amylase were measured using the small dryer and experimental rice milling machine milling methods described in Section 1 of the "Detection Methods" section. The results are shown in Table 1.

[0164] Freshly harvested rice is subjected to slow tempering and drying, with the wind temperature controlled at 50℃, the rice temperature controlled at around 38℃, and the water reduction rate controlled at 0.6% / h, until the rice moisture content is 15±0.5%.

[0165] After drying and equilibration for 48 hours, four parallel samples were taken from the discharge port of the drying tower, each weighing 1 kg. The moisture content of the equilibrated paddy was 15.1%. The parameters of the equilibrated paddy were tested according to the method described above, and the yield per mu (unit of land area) was calculated. The results are shown in Table 2. The parameters of the rice samples obtained by milling using the rice polishing machine described in section 1 of the "Test Methods" section are shown in Table 3.

[0166] Table 1: Enzyme activity after rice harvest

[0167]

[0168]

[0169] Table 2: Comparison of Rice Harvest Yield and Drying Quality

[0170]

[0171] As shown in Table 2, although the tempering and drying treatment was the same, there were significant differences in yield, cracking rate, and germination rate when rice was harvested under different enzyme activity conditions. Harvesting under the enzyme activity conditions of Example 1 resulted in a higher yield, achieving increased income within the rice processing industry; at the same time, the cracking rate was low and the germination rate was high.

[0172] The parameters of the final rice were tested, and the results are shown in Table 3.

[0173] Table 3: Rice Quality

[0174]

[0175] As can be seen from Table 3, the rice in Example 1 has a richer aroma, higher taste and flavor scores, and lower amylose and protein content. Generally speaking, amylose and protein content are inversely proportional to taste scores, which further supports the reason why the rice in Example 1 has a higher taste score.

[0176] Example 2: Different drying treatments

[0177] Comparative Example 2

[0178] Daohuaxiang No. 2 rice with a moisture content of 19.2% obtained from batch harvesting in Example 1 was continuously dried. The rice temperature was controlled at around 50°C during drying, and the rice was repeatedly circulated using an external lifting device until the moisture content of the rice was 15±0.5%, at which point drying was stopped. After drying, the rice was allowed to equilibrate for 48 hours. Four parallel samples, each weighing 1 kg, were then taken from the discharge port of the drying tower.

[0179] The breakage rate of paddy rice before and after continuous drying was tested using the method described above. The rice was milled using the experimental rice milling machine described in section 1 of the "Test Methods" section, and the parameters of the resulting rice were tested. The results are shown in Table 4 below.

[0180] Table 4: Increased rice cracking rate and enzyme activity and rice quality of the prepared rice

[0181]

[0182] The rice in Example 1 and Comparative Example 2 was harvested under the same conditions, therefore the quality of the rice was the same. However, the drying treatment in Example 1 was a slow tempering drying, with a relatively slow moisture reduction and a tempering period, while Comparative Example 2 used a conventional continuous drying treatment, with a relatively fast moisture reduction rate and no tempering period. As shown in the table above, the rice obtained by different drying treatments had different increases in the rate of cracking and enzyme activity. Compared with Comparative Example 2, the rice obtained in Example 1 had a lower increase in the rate of cracking and higher enzyme activities of peroxidase, superoxide dismutase, catalase, and α-amylase. Furthermore, as... Figure 2 As shown, regardless of whether it is paddy rice or white rice, after different drying treatments, the germination index, vitality index and germination rate of the paddy rice in Example 1 are higher, and the taste, freshness and aroma of the prepared rice are better.

[0183] Example 2

[0184] A batch of *Euphorbia milii* rice was harvested. 42 days after heading, the moisture content of the fresh rice was measured to be 28.5%. The fresh rice was dried using a "first equalize moisture, then reduce moisture" process. Specifically, hot air at approximately 48°C was first blown onto the fresh rice to equalize the moisture content, reducing the moisture gradient to within 2 percentage points. Then, a reducing moisture process (slow tempering drying) was implemented, involving blowing hot air at 55°C to control the rice temperature at around 38°C, with a reducing rate of 0.85% / h. Once the rice moisture content dropped to 18.0%, the air temperature was controlled at 50°C, and the reducing rate at 0.60% / h, until the rice moisture content reached 15±0.5%, at which point drying was stopped.

[0185] After drying and equilibration for 48 hours, four parallel samples (1 kg each) were taken from the discharge port of the drying tower. The moisture content of the rice after equilibration was 14.8%. The increase in rice cracking rate was detected. The rice was milled using a rice milling machine as described in Section 1 of the "Detection Methods" section, and the parameters of the obtained rice were tested. The results are shown in Table 5.

[0186] Comparative Example 3

[0187] Fresh rice with a moisture content of 28.5% obtained from the batch harvest in Example 2 was subjected to slow tempering and drying. Uneven moisture was removed by directly using hot air at 55°C, with the rice temperature controlled at approximately 38°C and the moisture removal rate controlled at 0.85% / h. After the rice moisture content dropped to 18.5%, the air temperature was controlled at 50°C and the moisture removal rate controlled at 0.65% / h, until the rice moisture content reached 15±0.5%, at which point drying was stopped.

[0188] After drying and equilibration for 48 hours, four parallel samples (1 kg each) were taken from the discharge port of the drying tower. The moisture content of the rice after equilibration was 14.9%. The increase in rice cracking rate was detected. The rice was milled using a rice milling machine as described in Section 1 of the "Detection Methods" section, and the parameters of the obtained rice were tested. The results are shown in Table 5.

[0189] Table 5: Increased rice cracking rate and enzyme activity and rice quality of the prepared rice

[0190]

[0191] As shown in the table above, the rice obtained by different drying methods has different increases in the rate of cracking and enzyme activity. Compared with Comparative Example 3, the rice obtained in Example 2 has a lower increase in the rate of cracking and higher enzyme activities of peroxidase, superoxide dismutase, catalase and α-amylase, resulting in better rice quality.

[0192] Example 3: Different storage methods, same storage method for different harvests

[0193] Example 3

[0194] The equilibrated sample with a moisture content of 15.3% obtained in Example 1 was placed in a low-temperature warehouse for storage, with the temperature of the entire warehouse controlled below 15°C. After 4 months of storage, 4 parallel samples were taken, each weighing 1 kg. The freshness and mold count of the stored rice were tested according to the method described above. The rice was milled using the experimental rice milling machine described in Section 1 of the "Detection Methods" section, and the parameters of the resulting rice were tested. The results are shown in Table 6.

[0195] Comparative Example 4

[0196] The equilibrated sample with a moisture content of 15.3% obtained in Example 1 was stored in a room temperature warehouse. After 4 months of storage, 4 parallel samples were taken, each weighing 1 kg. The freshness and mold count of the stored rice were tested according to the method described above. The rice was milled using the experimental rice milling machine described in Section 1 of the "Detection Methods" section, and the parameters of the resulting rice were tested. The results are shown in Table 6.

[0197] Comparative Example 5

[0198] The equilibrium sample with a moisture content of 15.1% obtained from Comparative Example 1 was taken and stored in a low-temperature warehouse, with the temperature of the entire warehouse controlled below 15℃. After 4 months of storage, 4 parallel samples were taken, each weighing 1 kg. The freshness and mold count of the stored rice were tested according to the method described above. The rice was milled using the experimental rice milling machine described in Section 1 of the "Detection Methods" section, and the parameters of the resulting rice were tested. The results are shown in Table 6.

[0199] Table 6: Freshness, Mold, and Rice Quality of Paddy After Storage

[0200]

[0201] As can be seen from Examples 3 and 4, the quality of paddy rice varies considerably under different storage conditions. Whether considering paddy rice quality (mold, freshness) or rice quality (enzyme activity, palatability, and aroma), low-temperature storage is superior to room-temperature storage.

[0202] As can be seen from Examples 3 and 5, even under the same low-temperature storage conditions, different harvesting conditions resulted in differences in rice quality. Rice harvested under the enzyme-activated conditions of Example 1 exhibited superior freshness, palatability, and aroma compared to Comparative Example 4. Furthermore, the total number of mold colonies indicated that rice harvested under the enzyme-activated conditions of Example 1 contained less mold and was more resistant to storage.

[0203] Example 4: Same harvesting conditions, different grinding ratios

[0204] Example 4-1

[0205] The Deyu 317 rice variety is harvested 60 days after heading. After harvesting, samples are taken to measure the moisture content of the fresh rice, which is 17.2%, and then it undergoes slow tempering and drying. The wind temperature is controlled at 50℃, and the water precipitation rate is controlled at 0.6% / h, until the moisture content of the rice is 15±0.5%, at which point drying is stopped.

[0206] After equilibration, the sample is taken and stored in a low-temperature chamber, with the temperature of the entire chamber controlled below 15°C.

[0207] After 4 months of storage, the rice is processed. A two-roller (sand roller, Satake VTA10AB-C model, sand grade 30#) and two iron roller rice milling machines (Satake VBF10A-C model) are used. The pressure and current values ​​for each rice milling machine can be 75A, 73A, 95A, and 90A respectively; the flow rate is controlled at 35t / h. Specifically, after the first sand roller (first sand) roughening process, the proportion of rice bran flakes retained by the 60-mesh sieve after passing through the second sand process (second sand) should be 52% of all rice bran flakes removed. The grinding ratio for the second and third rice milling processes is 68.5%, while the final grinding ratio is 22.5%. The final rice milling precision achieves a whitening rate of 90.5%.

[0208] Example 4-2

[0209] The equilibrated sample with a moisture content of 15.3% obtained in Example 1 was pulled into a low-temperature warehouse for storage, and the temperature of the entire warehouse was controlled below 15°C.

[0210] After 4 months of storage, the rice is processed. A three-roller, one-iron milling process is used (three rollers: Satake VTA10AB-C model, roller grade 30#; one iron mill: Satake VBF10A-C model). The pressure of each rice milling process is: first roller: 72A, second roller: 65A, third roller: 70A, first iron mill: 93A. The flow rate is controlled at 34t / h. Specifically, after the first roller (first roller) roughening, the rice bran flakes removed in the second process (second roller) must account for 55% of the total mass of rice bran flakes retained by the 60-mesh sieve. The milling ratio for the second and third rice milling processes is 66.5%, while the final milling ratio is 24.5%. The final rice milling precision achieves a whitening rate of 89.5%.

[0211] Comparative Example 6

[0212] The balanced sample with a moisture content of 15.3% obtained in Example 1 was pulled into a low-temperature warehouse for storage, and the temperature of the entire warehouse was controlled below 15°C.

[0213] After 4 months of storage, the rice is processed. A three-roller, one-iron milling process is used (three rollers: Satake VTA10AB-C model, 30# sand; one iron mill: Satake VBF10A-C model). The pressure of each rice milling process is: first roller: 80A, second roller: 70A, third roller: 65A, first iron mill: 93A. The flow rate is controlled at 34t / h. Specifically, after the first roller (first sand) roughening, the rice bran flakes removed in the second process (second sand) should account for 45% of the total rice bran flakes retained by the 60-mesh sieve. The milling ratio for the second and third rice milling processes is 50.5%, while the final milling ratio is 25.5%. The final rice milling precision achieves a whitening rate of 89.5%.

[0214] Comparative Example 7

[0215] The balanced sample with a moisture content of 15.3% obtained in Example 1 was pulled into a low-temperature warehouse for storage, and the temperature of the entire warehouse was controlled below 15°C.

[0216] After 4 months of storage, the rice is processed. A three-roller, one-iron milling process is used (three rollers: Satake VTA10AB-C model, roller grade 30#; one iron mill: Satake VBF10A-C model). The pressure of each rice milling process is: first roller: 72A, second roller: 78A, third roller: 65A, first iron mill: 93A. The flow rate is controlled at 34t / h. Specifically, after the first roller (first roller) roughening, the rice bran flakes removed in the second process (second roller) should account for 55% of the total mass of rice bran flakes retained by the 60-mesh sieve. The grinding ratio for the second and third rice milling processes is 75.5%, while the grinding ratio for the final process is 15%. The final rice milling precision achieves a whitening rate of 89.5%.

[0217] Table 7 below shows the different milling methods of Examples 4-1, 4-2, Comparative Example 6, and Comparative Example 7. The enzyme activity, eating value, taste, and aroma of the rice obtained in Examples 4-1, 4-2, Comparative Example 6, and Comparative Example 7 were tested according to the methods described above, and the broken rice rate was calculated. The results are shown in Table 8 below.

[0218] Table 7 Grinding Methods

[0219]

[0220] Table 8. Quality of Rice After Milling

[0221]

[0222] Different grain types often require different processing methods. For example, Deyu 317 in Example 4-1 is a long-grain rice, but significantly shorter than Daohuaxiang 2, so it uses a two-grit, two-iron milling process. Daohuaxiang 2, on the other hand, primarily uses a sand roller mill, employing a three-grit, one-iron milling process. Different varieties and different processes, as long as the milling ratio is properly controlled, can all achieve high yields, low temperature rises, and good quality rice.

[0223] As can be seen from Examples 4-1, 4-2, and Comparative Examples 6 and 7, different milling methods have a significant impact on the quality of rice: reasonable milling distribution can improve efficiency, reduce broken rice rate and processing temperature rise, thereby affecting the taste, aroma, and flavor of the rice (Examples 4-1 and 4-2). If the milling is over-milled at the beginning or in the middle, i.e., the work done on the rice grains is unreasonable, it will lead to an increase in broken rice (especially long-grain rice), and the temperature rise will also increase sharply (Comparative Examples 6 and 7).

[0224] Example 5: Different Harvesting and Grinding Methods

[0225] Example 5

[0226] The equilibrated sample with a moisture content of 15.1% obtained from Comparative Example 1 was taken and stored in a low-temperature warehouse, with the temperature of the entire warehouse controlled below 15℃.

[0227] After 4 months of storage, the rice is processed. A three-roller, one-iron milling process is used (three rollers: Satake VTA10AB-C model, roller grade 30#; one iron mill: Satake VBF10A-C model). The pressure of each rice milling process is: first roller: 72A, second roller: 65A, third roller: 70A, first iron mill: 93A. The flow rate is controlled at 34. Specifically, after the first roller (first roller) roughening, the rice bran flakes removed in the second process (second roller) should account for 56.5% of the total rice bran flakes retained by the 60-mesh sieve. The milling ratio for the second and third rice milling processes is 66.3%, and the final milling ratio is 25.5%. The final rice milling precision achieves a whitening rate of 89.5%.

[0228] Comparative Example 8

[0229] The balanced sample with a moisture content of 15.1% obtained from Comparative Example 1 was pulled into a low-temperature warehouse for storage, and the temperature of the entire warehouse was controlled below 15℃.

[0230] After 4 months of storage, the rice is processed. A three-roller, one-iron milling process is used (three rollers: Satake VTA10AB-C model, roller grade 30#; one iron mill: Satake VBF10A-C model). The pressure of each rice milling process is: first roller: 80A, second roller: 70A, third roller: 65A, first iron mill: 93A. The flow rate is controlled at 34. Specifically, after the first roller (first roller) roughening, the rice bran flakes removed in the second process (second roller) should account for 47.5% of the total rice bran flakes retained by the 60-mesh sieve. The milling ratio for the second and third processes is 51.5%, and the final milling ratio is 27.5%. The final rice milling precision achieves a whitening rate of 89.5%.

[0231] Table 9 below shows the harvesting conditions and processing methods for Examples 4-2, Comparative Example 6, Example 5, and Comparative Example 8. The palatability, taste, and aroma of the rice obtained from Examples 4-2, Comparative Example 6, Example 5, and Comparative Example 8 were tested according to the methods described above, and the broken rice rate was calculated. The results are shown in Table 10 below.

[0232] Table 9 Harvesting conditions and processing methods

[0233] Examples / Comparative Examples Harvesting conditions Processing method Temperature rise, °C Example 4-2 Example 1 Low temperature rise milling 18.5 Comparative Example 6 Example 1 Normal milling 24.7 Example 5 Comparative Example 1 Low temperature rise milling 19.2 Comparative Example 8 Comparative Example 1 Normal milling 26.3

[0234] Table 10 Rice Quality

[0235]

[0236] As shown in the table above, under the same harvesting conditions, rice milled at low temperature has a lower broken rice rate, higher taste, flavor and aroma, and consumes less electricity.

[0237] Example 6: Different Enzyme Activities

[0238] Example 6

[0239] The Deyu 317 rice variety was harvested 60 days after heading. The moisture content of fresh rice was measured using the small-scale dryer and experimental rice milling method described in Section 1 of the "Detection Methods" document, including POD, SOD, CAT, and α-amylase content.

[0240] The moisture content of fresh rice is 17.2%. The freshly harvested rice is subjected to slow tempering and drying, with the air temperature controlled at 50℃ and the moisture reduction rate controlled at 0.6% / h, until the moisture content of the rice is 15±0.5%, at which point the drying process is stopped.

[0241] Four parallel samples were taken at the discharge port of the drying tower, each weighing 1 kg. After equilibration, the moisture content of the rice was 14.9%. The rice was then stored in a low-temperature warehouse for 4 months. After storage, four parallel samples were taken again, each weighing 1 kg. The parameters of the rice samples obtained from the rice milling machine were determined according to the test parameters described in Section 1 of the "Test Methods" section.

[0242] Comparative Example 9

[0243] The Deyu 317 rice variety is harvested 65 days after heading. After harvesting, samples are taken to measure the contents of POD, SOD, CAT, α-amylase, and moisture. A slow tempering and drying process is then carried out using a dryer. The moisture content of the fresh rice is 16.3%, the air temperature is controlled at 50℃, and the water removal rate is controlled at 0.55% / h until the moisture content of the rice is 15±0.5%, at which point the drying process is stopped.

[0244] Four parallel samples were taken at the discharge port of the drying tower, each weighing 1 kg. After equilibration, the moisture content of the rice was 14.8%. The rice was then stored in a low-temperature warehouse for four months. After storage, four parallel samples were taken again, each weighing 1 kg. The parameters of the rice samples obtained from the rice milling machine were determined according to the test parameters described in Section 1 of the "Test Methods" section.

[0245] Example 7

[0246] The Nongjing 306 rice variety was harvested 65 days after heading. After harvesting, samples were taken to measure the contents of POD, SOD, CAT, α-amylase and moisture content. The rice was then subjected to slow tempering drying using a dryer. The moisture content of the fresh rice was 17.3%, the air temperature was controlled at 50℃, and the water removal rate was controlled at 0.60% / h until the moisture content of the rice was 15±0.5%, at which point the drying was stopped.

[0247] Four parallel samples were taken at the discharge port of the drying tower, each weighing 1 kg. After equilibration, the moisture content of the rice was 14.9%. The rice was then stored in a low-temperature warehouse for 4 months. After storage, four parallel samples were taken again, each weighing 1 kg. The parameters of the rice samples obtained from the rice milling machine were determined according to the test parameters described in Section 1 of the "Test Methods" section.

[0248] Comparative Example 10

[0249] The Nongjing 306 rice variety was harvested 71 days after heading. After harvesting, samples were taken to measure the contents of POD, SOD, CAT, α-amylase, and moisture content. The rice was then subjected to slow tempering drying using a dryer. The moisture content of the fresh rice was 16.4%, the air temperature was controlled at 50℃, and the water removal rate was controlled at 0.55% / h until the moisture content of the rice was 15±0.5%, at which point the drying process was stopped.

[0250] Four parallel samples were taken at the discharge port of the drying tower, each weighing 1 kg. After equilibration, the moisture content of the rice was 14.9%. The rice was then stored in a low-temperature warehouse for 4 months. After storage, four parallel samples were taken again, each weighing 1 kg. The parameters of the rice samples obtained from the rice milling machine were determined according to the test parameters described in Section 1 of the "Test Methods" section.

[0251] Comparative Example 11

[0252] The Nongjing 306 rice variety is harvested 76 days after heading. After harvesting, samples are taken to measure the contents of POD, SOD, CAT, α-amylase, and moisture content. A slow tempering drying process is then carried out using a dryer. The moisture content of the fresh rice is 15.8%, the direct air temperature is controlled at 50℃, and the water removal rate is controlled at 0.55% / h. Drying is stopped when the moisture content of the rice is 15±0.5%.

[0253] Four parallel samples were taken from the discharge port of the drying tower, each weighing 1 kg. After equilibration, the moisture content of the rice was 14.7%. The rice was then transferred to a low-temperature storage chamber for storage. After four months of storage, four parallel samples were taken again, each weighing 1 kg. The parameters of the rice samples obtained from the rice milling machine were determined according to the test parameters described in Section 1 of the "Test Methods" section.

[0254] The results of various parameters are shown in the table below. The POD, SOD, CAT, α-amylase content and moisture content of rice from Examples 6 to 7 and Comparative Examples 9 to 11 were measured after harvest, as well as the freshness, palatability and rice mold after 4 months of storage.

[0255] Table 11 Rice Quality

[0256]

[0257] As shown in Table 11, the trends of the four enzymes during rice growth are inconsistent, and not all four enzymes are within the range required by this invention at harvest. As shown in Example 6 and Comparative Example 9, when the POD enzyme in the rice variety Deyu 317 (Comparative Example 9) does not meet the requirements, the freshness, anti-mold effect, and eating quality of the rice are slightly worse than in Example 6. As shown in Example 7 and Comparative Examples 10-11, the SOD enzyme in Comparative Example 10 is not within the range required by this invention, while the other three enzymes are within the range. The activities of all four enzymes in Comparative Example 11 are not within the range required by this invention, and their quality is slightly worse than in Example 7. Therefore, high-quality rice can only be obtained when the activities of all four enzymes meet the above-mentioned ranges.

[0258] Furthermore, as shown in the table above, the number of days after heading cannot be used as a standard for determining the harvest time. For example, Deyu 317 (Comparative Example 9) was harvested 65 days after heading, and its enzyme activity was already outside the range required by this application, resulting in poor rice quality; while Nongjing 306 (Example 7), which was also harvested 65 days after heading, still had enzyme activity within the range required by this application. Therefore, due to the differences in rice varieties, the number of days after heading cannot be used to replace the monitoring of rice enzyme activity.

[0259] Example 7: Comparison of Competitive Product Quality

[0260] Example 8

[0261] The rice product obtained from the harvesting and milling process in Example 4-2 was used. The rice was placed in a constant temperature and humidity chamber at 35°C and 75% humidity for accelerated aging for 6 weeks to simulate the shelf life of finished rice. The changes in the four enzyme activities, taste, aroma, and palatability values ​​of the rice in the above examples and comparative examples were measured every two weeks. The results are shown in Tables 12-19 below.

[0262] Comparative Examples 12-14

[0263] Three commercially available brands of Daohuaxiang No. 2 rice (brand A, brand B, and brand C, 10kg packages) were purchased as Comparative Examples 12, 13, and 14, respectively. Their production dates deviated from those of Example 7 by no more than two weeks. The rice was placed in a constant temperature and humidity chamber at 35°C and 75% humidity for accelerated aging for 6 weeks to simulate the shelf life of finished rice. The changes in four enzyme activities, taste, aroma, and palatability values ​​of the rice in the above examples and comparative examples were measured every two weeks. The results are shown in Tables 12-19 below.

[0264] Table 12: Quality Comparison Results of Four Daohuaxiang No. 2 Rice Products at Week 0 of Shelf Life

[0265]

[0266] Table 13: Changes in POD enzymes during accelerated shelf life

[0267] Accelerated storage time / weeks 0 2 4 6 Drop (6-0) Drop (4-0) Example 8 382 350 330 315 17.54％ 13.61％ Comparative Example 12 460 350 310 305 33.70％ 32.61％ Comparative Example 13 360 250 220 180 50.00％ 38.89％ Comparative Example 14 345 265 230 210 39.13％ 33.33％

[0268] Note: "Decrease (6-0)" indicates the decrease in enzyme activity at 6 weeks and 0 weeks of shelf life, and "Decrease (4-0)" indicates the decrease in enzyme activity at 4 weeks and 0 weeks of shelf life.

[0269] Table 14: Changes in SOD enzyme activity during accelerated shelf life

[0270]

[0271] Table 15: Changes in CAT enzymes during accelerated shelf life

[0272]

[0273]

[0274] Table 16: Changes in α-amylase during accelerated shelf life

[0275]

[0276] Table 17: Changes in Rice Flavor During Accelerated Shelf Life

[0277]

[0278] Table 18: Changes in rice aroma during accelerated shelf life

[0279] Accelerated storage time / weeks 0 2 4 6 Drop (6-0) Drop (4-0) Example 8 782.25 563.25 458.49 419.01 46.44％ 41.93％ Comparative Example 12 772.13 487.37 423.67 367.87 52.36％ 45.13％ Comparative Example 13 752.71 498.16 410.29 359.23 52.28％ 45.49％ Comparative Example 14 760.25 487.19 387.87 339.57 55.33％ 48.98％

[0280] Table 19: Changes in the taste value of cooked rice during accelerated shelf life

[0281] Accelerated storage time / weeks 0 2 4 6 Drop (6-0) Drop (4-0) Example 8 86.5 84.5 79.5 76.3 11.79％ 8.09％ Comparative Example 12 86.3 84.3 77.8 73.4 14.95％ 9.85％ Comparative Example 13 82.5 81.6 75.7 69.5 15.76％ 8.24％ Comparative Example 14 82.7 81.7 76.4 71.7 13.30％ 7.62％

[0282] As shown in Table 12, due to the influence of geographical environment, planting level and climate, although the rice comes from the same variety, there are differences in quality, but it is still within the quality range of rice varieties such as Daohuaxiang No. 2. For example, in terms of sensory evaluation (taste, flavor and aroma), the finished rice of Comparative Example 12 is similar to the product of Example 8, while the finished rice of Comparative Examples 13 and 14 has slightly worse sensory evaluation.

[0283] The accelerated shelf-life experiment over 6 weeks (as shown in Tables 13 to 19) revealed that the reductions in enzyme activity, taste, aroma, and palatability of the four types of Daohuaxiang No. 2 rice products were not uniform. Specifically, due to strict control over harvesting, drying, storage, and processing, the rice in Example 8 exhibited relatively smaller reductions in the four enzyme activities and better stability. This was also reflected in the sensory evaluation of the cooked rice; the reductions in taste, aroma, and palatability in Example 8 were all less than those in Comparative Examples 12-14, and the specific sensory evaluation scores for each cycle were also superior.

Claims

1. A method for milling brown rice, the method comprising the steps of hulling and polishing, characterized in that: the hulling satisfies the condition that the mass of the rice bran pieces retained by the screen after the rice bran pieces removed in the first step of polishing after hulling are passed through a 60-mesh screen is in the range of 50-60% of the total rice bran pieces removed; and the polishing satisfies the condition that the sum of the polishing distribution ratios of all other steps of polishing except the last step of polishing is in the range of 60-70%, preferably 67±2%, and the polishing distribution ratio of the last step of polishing is in the range of 20-30%, preferably 23±2%. The milling is performed using the method of claim 1. The harvesting includes harvesting paddy rice in which the enzyme activities of peroxidase, superoxide dismutase, catalase, and α-amylase are in the following ranges: the enzyme activity of peroxidase is 250-800 U / g, the enzyme activity of superoxide dismutase is 5700-6500 U / g, the enzyme activity of catalase is 5.0-25.0 U / g, and the enzyme activity of α-amylase is 330-360 seconds.

2. A rice processing method comprising the steps of harvesting, drying, equilibrating, storing, hulling and separating the husk, and milling; characterized in that, The drying includes performing a slow drying on the freshly harvested paddy rice, and optionally performing a water equalization before the slow drying; wherein if the freshly harvested paddy rice has a moisture content higher than 25 wt%, the water equalization and the slow drying are performed in sequence; and if the freshly harvested paddy rice has a moisture content less than or equal to 25 wt%, the slow drying is directly performed.

3. The rice processing process according to claim 2, wherein, Preferably, the water equalization is performed at a temperature lower than the drying temperature by 3-5 °C, and the moisture gradient between the paddy rice is reduced to within 2 percentage points.

4. The rice processing method according to claim 2 or 3, wherein Preferably, the slow drying is divided into two stages, the first stage aims to reduce the moisture content of the paddy rice to 18%±0.5%, and the second stage aims to further reduce the moisture content of the paddy rice to 14.5%±1%; wherein if the moisture content of the paddy rice to be slowly dried is already below 18%, the second stage is directly entered. Preferably, in the first stage, the drying temperature is controlled to be in the range of 55-62 °C, and the grain temperature is maintained below 38 °C. Preferably, in the second stage, the drying temperature is reduced by 5 °C or less than the first stage, and the drying temperature is preferably 50-56 °C, and the grain temperature is controlled to be below 38 °C. In the drying, when the moisture content of the paddy rice is higher than 30 wt%, the moisture reduction rate is controlled to be at most 1.3 wt% per hour; when the moisture content of the paddy rice is in the range of 22-30 wt%, the moisture reduction rate is controlled to be at most 1 wt% per hour; when the moisture content of the paddy rice is in the range of 18-22 wt%, the moisture reduction rate is controlled to be at most 0.85 wt% per hour; and when the moisture content of the paddy rice is in the range of 15-18 wt%, the moisture reduction rate is controlled to be at most 0.65 wt% per hour.

6. The rice processing method according to any one of claims 2-5, characterized in that: the dried paddy rice is transported to a dry warehouse for standing and equilibration, and is stored after being completely cooled; 5. The rice processing method according to any one of claims 2 to 4, wherein After the paddy rice is stored, low-temperature storage is performed, i.e., the average grain temperature is maintained below 15 °C, and the local maximum grain temperature is not more than 20 °C. ​ ​ ​ Preferably, during storage, the quality of the rice is monitored by germination rate, freshness, and white rice enzyme activity; wherein, after storage, the rice satisfies the following ranges: germination rate ≥ 90%; freshness ≥ 85 points; and, compared to the enzyme activity at harvest, the enzyme activity retention rates of peroxidase, superoxide dismutase, and catalase are all ≥ 80%, and the enzyme activity of α-amylase, measured in terms of falling number, is within 450 s.

7. Rice, characterized in that: the decrease in the taste of the rice is not higher than 21.00%, preferably not higher than 20.50%, after the rice is milled and placed in a constant temperature and humidity box at 35°C and 75% humidity for 6 weeks, wherein the taste is measured according to the method of GBT 15682-2008; and / or the decrease in the concentration of 2-acetyl pyrroline, which is a volatile flavor substance in the rice, is not higher than 48.00%, preferably not higher than 46.50%, after the rice is milled and placed in a constant temperature and humidity box at 35°C and 75% humidity for 6 weeks; and / or the decrease in the eating value of the rice is not higher than 13.00%, preferably not higher than 12.00%, after the rice is milled and placed in a constant temperature and humidity box at 35°C and 75% humidity for 6 weeks; Preferably, the rice variety is Lianhuaxiang No.

2.

8. The rice of claim 7, wherein, the decrease in the enzyme activity of POD, the enzyme activity of SOD, the enzyme activity of CAT, and the enzyme activity of α-amylase of the rice after the rice is milled and placed in a constant temperature and humidity box at 35°C and 75% humidity for 6 weeks, compared to the enzyme activity of POD, the enzyme activity of SOD, the enzyme activity of CAT, and the enzyme activity of α-amylase of the rice immediately after milling, is not higher than 20.00%, 20.00%, 55.00%, and 25.00%, respectively; Preferably, the decrease in the enzyme activity of POD is not higher than 18.00%, more preferably not higher than 17.60%; and / or, the decrease in the enzyme activity of SOD is not higher than 18.50%, more preferably not higher than 18.00%; and / or, the decrease in the enzyme activity of CAT is not higher than 53.00%, preferably not higher than 51.50%; and / or, the decrease in the enzyme activity of α-amylase is not higher than 24.90%.

9. Rice obtained by the milling method of claim 1 and / or the processing technology of any one of claims 2-6, rice products containing the rice or the rice of claim 7 or 8, rice cooked from the rice or the rice products, or food containing the rice or the rice products.

10. Use of the milling method of claim 1 and / or the processing technology of any one of claims 2-6 in one or more of the following aspects: (1) reducing or slowing down the decrease in the enzyme activity of POD, SOD, CAT, and α-amylase of the rice; (2) improving the freshness of the rice; (3) reducing the increase in the broken waist rate of the rice; (4) reducing the germination rate of the rice; (5) improving the mold resistance of the rice; (6) improving the eating value, taste, and aroma of the rice; (7) prolonging the shelf life of the rice; (8) reducing the broken rice rate of the rice; (9) reducing the processing temperature rise of the rice; and (10) slowing down the decrease in the quality of the rice.

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