A gradient temperature difference processing method for controlling rancidity deterioration of rice bran decoction pieces

Abstract

The application provides a gradient temperature difference processing method for preventing and controlling rancidity and deterioration of rice bran decoction pieces, comprising the following steps: sequentially subjecting newly harvested rice bran to low-temperature rapid cooling, medium-temperature roasting, high-temperature roasting and second ultra-low-temperature rapid cooling after removing impurities by primary screening, so as to prevent and control rancidity and deterioration of rice bran decoction pieces. The application utilizes rapid and strong temperature difference change to prevent and control the reaction after grinding contact oxidation, destroys the autoxidation system of rice bran, effectively prevents and controls the generation of oxidized toxic substances and the breeding and pollution of harmful microorganisms, and ensures the safety and effectiveness of medication.

Description

Technical Field

[0001] This invention relates to the field of quality control technology, and provides a gradient temperature difference processing method for preventing the rancidity and deterioration of rice bran slices. Background Technology

[0002] Rice bran is a traditional Chinese medicine with a medicinal history of over 1800 years. It is a byproduct of rice milling after hulling, consisting of the rice's seed coat, aleurone layer, embryo, and a small amount of endosperm. It is commonly known as rice bran, rice husk, or rice bran. Recent domestic and international research has shown that rice bran concentrates 64% of the nutrients found in rice, over 90% of the essential elements for the human body, and nearly 100 bioactive factors with various functions. It possesses remarkable physiological functions, including preventing cardiovascular disease, regulating blood sugar, aiding weight loss, preventing tumors, combating fatigue, and beautifying the skin.

[0003] 1. The domestic rice bran processing industry is developing too slowly, mainly because:

[0004] 1.1 Rice bran contains oxidases that promote the oxidation of unsaturated fatty acids. When the temperature of rice bran is between 35℃ and 40℃, the unsaturated fatty acids can be oxidized and deteriorated within 6 hours. Oxidized rice bran will produce an oily smell. If people eat the deteriorated rice bran oil, it will harm multiple organs such as the human digestive tract and should not be consumed.

[0005] 1.2. Microorganisms in rice bran can accelerate the decomposition and spoilage of nutrients such as protein in rice bran at 35℃-40℃, while rice bran produces an unpleasant bran odor.

[0006] 2. A Brief Introduction to the Traditional Rice Bran Processing Technique

[0007] Under normal circumstances, the rice bran freshly milled from a rice mill is prone to rapid microbial growth due to the frictional heat generated during the milling process, and it is also highly susceptible to oxidation and spoilage within a short period of time. Because rice bran has poor heat transfer properties and is initially in powder form, conventional cooling methods using refrigeration equipment are characterized by low heat exchange efficiency, long processing times, and high energy consumption, making them unsuitable for large-scale production.

[0008] Table 1 shows the inclusion of traditional processing techniques for rice bran in Chinese medical literature, regulations, and standards.

[0009] Table 1. Summary of Rice Bran and Rice Products Received

[0010]

[0011] 3. Limitations of traditional methods for processing rice bran

[0012] Traditional methods of impurity removal primarily target non-medicinal impurities such as rice husks and sand, but they cannot effectively remove microorganisms at the microscopic level, nor can they prevent the rancidity and deterioration of rice bran. Due to the lack of effective treatment, rice bran often exhibits partial rancidity, deterioration, or even mold growth during storage and before processing. Simple sun-drying or ordinary drying methods often fail to control the moisture content below a safe range, easily leading to further rancidity or mold growth. Furthermore, these drying methods cannot effectively sterilize or kill mold, especially Aspergillus flavus, which requires temperatures above 280°C to be killed in a humid environment. Sun-drying or ordinary drying methods cannot inactivate it, and it remains difficult to inactivate even at subsequent decoction temperatures, thus affecting the safety of medication use.

[0013] With the evolution of rice processing technology and production capacity, modern rice bran is more prone to rancidity and deterioration, and the resulting oxidative toxic substances further threaten its medicinal safety. The oxidation of rice bran mainly occurs through two pathways: contact oxidation during grinding and auto-oxidation. Traditional processing methods such as stir-frying or sun-drying can inhibit oxidation reactions caused by friction to some extent, but they cannot prevent the auto-oxidation process of rice bran. This results in a short shelf life for currently prepared rice bran, typically not exceeding 10 days. More importantly, the toxic oxides produced during auto-oxidation can raise pharmaceutical safety concerns, limiting its clinical application.

[0014] Therefore, developing a gradient temperature difference processing method to prevent and control the rancidity and deterioration of rice bran slices has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0015] To address the problems mentioned in the background section, the main objective of this invention is to provide a gradient temperature difference processing method for controlling the rancidity and deterioration of rice bran slices. This invention employs alternating cooling-medium-high temperature-cooling temperature changes during drying to disrupt the self-oxidation system of rice bran, thereby controlling the generation and contamination by harmful microorganisms. Furthermore, this process complies with the general rules for processing traditional Chinese medicine slices in the Pharmacopoeia of the People's Republic of China.

[0016] In a first aspect, the present invention provides a gradient temperature difference processing method for preventing the rancidity and deterioration of rice bran slices. The method involves sequentially subjecting newly harvested rice bran slices to primary screening for impurity removal, low-temperature rapid cooling, medium-temperature stir-frying, high-temperature aroma extraction, and secondary ultra-low temperature rapid cooling to prevent the rancidity and deterioration of rice bran slices.

[0017] In some embodiments, the low-temperature rapid cooling refers to cooling the core temperature of freshly harvested rice bran to -10 to -5°C within 10 to 60 minutes under the action of a refrigerant at -10°C to 0°C.

[0018] In some embodiments, the time for the low-temperature rapid cooling is 10-60 min, preferably 20-30 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or any two of the above values ​​forming a range.

[0019] In some embodiments, during the rapid cooling at low temperatures, the center temperature is cooled to -5°C, -6°C, -7°C, -8°C, -9°C, -10°C, or any two of the above values ​​forming any one of the ranges.

[0020] In some embodiments, the rice bran after being rapidly cooled at low temperature is transported to the frying device by a conveyor belt at a speed of 5-10 kg / min to ensure that the core temperature of the rice bran fluctuates within the range of 1-5°C.

[0021] In some embodiments, the transport speed is 5 kg / min, 6 kg / min, 7 kg / min, 8 kg / min, 9 kg / min, 10 kg / min, or any two of the above values ​​forming any one of the ranges.

[0022] In some embodiments, the medium-temperature frying refers to frying rice bran that has been rapidly cooled at a low temperature at 50-70°C for 10-60 minutes, with the moisture content of the rice bran controlled at 5-10%. A fixed frying temperature and real-time monitoring of the moisture content of the fried material are used to prevent excessively long frying times.

[0023] In some embodiments, the medium-temperature frying time is 10-60 min, preferably 30-40 min, and any one of the following ranges is formed by any two of the following values: 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min.

[0024] In some embodiments, the temperature for medium-temperature stir-frying is any one of the ranges of 50°C, 55°C, 60°C, 65°C, 70°C, or any two of the above values.

[0025] In some embodiments, after the medium-temperature stir-frying, the moisture content is controlled at 5-10%, preferably any one of any two values ​​from 5-7%, 5%, 6%, 7%, 8%, 9%, 10%.

[0026] In some embodiments, after the medium-temperature stir-frying, the temperature is increased to 100-200°C at a rate of 5-10°C / min for high-temperature aroma extraction.

[0027] In some embodiments, the heating rate is 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, or any two of the above values ​​forming any one of the ranges.

[0028] In some embodiments, the high-temperature aroma-explosion refers to frying the rice bran, which has been roasted at a medium temperature, at 180-200°C for 1-10 minutes, while controlling the moisture content of the rice bran to below 5%. After the high-temperature aroma-explosion, the moisture content of the rice bran is controlled to below 5%, resulting in the product's unique aroma.

[0029] In some embodiments, the high-temperature aroma-exploding time is 1 to 10 minutes, preferably 1 minute, 1.5 minutes, 2.0 minutes, 2.5 minutes, 3.0 minutes, 3.5 minutes, 4.0 minutes, 4.5 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, or any two of the above values ​​forming a range.

[0030] In some embodiments, the temperature for high-temperature aroma extraction is any one of the following ranges: 180~190℃, 180℃, 185℃, 190℃, 195℃, 200℃, or any two of the above values.

[0031] In some embodiments, after the high-temperature aroma-frying, the moisture content is controlled below 5%, preferably any one of any two values ​​from 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or above.

[0032] In some embodiments, the rice bran after being fried at high temperature is transported to a fluidized bed rapid cooling device via a conveyor belt at a speed of 5-10 kg / min to ensure that the core temperature of the rice bran fluctuates within the range of 1-5°C.

[0033] In some embodiments, the transport speed is 5 kg / min, 6 kg / min, 7 kg / min, 8 kg / min, 9 kg / min, 10 kg / min, or any two of the above values ​​forming any one of the ranges.

[0034] In some embodiments, the secondary ultra-low temperature rapid cooling refers to the rapid cooling of the rice bran after high-temperature frying to below 5°C under the action of a refrigerant at -40°C to -20°C, with a cooling time of 10 to 60 minutes per 100 kg of frying rice bran product.

[0035] In some embodiments, the cooling time is 10-60 min, preferably 20-30 min, and any one of the following ranges is 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, or any two of the above values.

[0036] In some embodiments, the temperature of the secondary ultra-low temperature rapid cooling is any one of the following ranges: -40℃ to -20℃, -40℃, -35℃, -30℃, -25℃, -20℃, or any two of the above values.

[0037] In some embodiments, after the high-temperature aroma-frying, the moisture content is controlled below 5%, preferably any one of any two values ​​from 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or above.

[0038] Secondly, a rice bran slice is provided, which is prepared using the method described in this invention.

[0039] Compared with the prior art, one of the above technical solutions has the following advantages or beneficial effects:

[0040] This invention employs the following methods to prevent and control the rancidity and deterioration of rice bran slices: ① It uses timed, rapid, and drastic temperature changes to disrupt the self-oxidation system of rice bran, effectively preventing its slow self-oxidation and simultaneously inhibiting the growth and contamination of harmful microorganisms; ② The processing method of this invention conforms to the general rules for processing Chinese medicinal slices in the Pharmacopoeia, and can disrupt its self-oxidation process through rapid temperature gradient changes, ensuring medication safety; ③ Traditional Chinese medicine frying processes include direct frying, frying with bran, frying with wine, and frying with soil, but none of these involve temperature difference changes. The gradient temperature difference method provided by this invention is a new processing method for Chinese medicine, which can effectively solve the problem of rancidity and deterioration of rice bran slices.

[0041] This invention represents a significant improvement over traditional processing methods: upgrading the simple heating and drying process (sun-drying or stir-frying) to a hot-cold alternating drying process of "cooling-medium temperature-high temperature-cooling." This process, through rapid temperature changes, effectively disrupts the autooxidase system of rice bran and blocks subsequent oxidation reactions during grinding. Thus, it inhibits the production of oxidative toxic substances at the source, while also suppressing the growth and contamination of harmful microorganisms, thereby significantly improving the safety and efficacy of rice bran in medicinal applications.

[0042] In the processing method of this invention, the first rapid cooling solves the problem of the large amount of heat and high humidity generated by modern rice mechanical processing, and reduces the oxidation and deterioration of rice bran during and shortly after rice processing, as well as the growth and contamination of harmful microorganisms.

[0043] In the processing method of this invention, the medium-temperature stir-frying process can reduce the moisture content of rice bran, achieving the first-step drying effect.

[0044] In the processing method of this invention, the high-temperature roasting process achieves complete drying and further sterilizes the rice bran, removes bran odor, and inactivates peroxidase activity, while accelerating the release of beneficial components and enhancing the aroma of the rice bran.

[0045] In the processing method of this invention, the secondary ultra-low temperature rapid cooling process rapidly reduces the temperature of the product after the aroma is released from above 100°C to below 5°C. At this temperature, the rate of rancidity of oils in rice bran is greatly reduced.

[0046] The method of this invention strictly controls the temperature of materials during transportation, achieving stable transfer and ensuring effective connection of each step. In industrial production, it can be managed and controlled by computer throughout the entire production line, saving labor costs and improving production efficiency. Attached Figure Description

[0047] Figure 1 The graph shows the change in peroxide value of different rice bran at different storage temperatures in Experiment 1 to verify the effect.

[0048] Figure 2 The graph shows the changes in peroxide value of rice bran raw material and two different medicinal slices in Experiment 2 to verify the effect.

[0049] Terminology Explanation

[0050] Certain embodiments of the invention will now be described in detail, examples of which are illustrated by the accompanying structural and chemical formulas. The invention is intended to cover all alternatives, modifications, and equivalents, all of which are included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many similar or equivalent methods and materials can be used to practice the invention. The invention is by no means limited to the methods and materials described herein. In the event that one or more of the incorporated documents, patents, and similar materials differ from or contradict this application (including, but not limited to, defined terminology, application of terminology, described techniques, etc.), this application shall prevail.

[0051] It should be further appreciated that certain features of the invention, for clarity, have been described in multiple independent embodiments, but may also be provided in combination in a single embodiment. Conversely, various features of the invention, for brevity, have been described in a single embodiment, but may also be provided individually or in any suitable sub-combination.

[0052] Unless otherwise stated, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. All patents and publications related to this invention are incorporated herein by reference in their entirety.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0054] In the following content, all numbers disclosed herein, whether or not they use words such as "approximately" or "about," are approximate values. The value of each number may vary by 1%, 2%, 5%, 7%, 8%, 10%, 15%, or 20%. Whenever a number with a value of N is disclosed, any numbers with values ​​of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, N+ / -10%, N+ / -15%, or N+ / -20% will be explicitly disclosed, where "+ / -" indicates addition or subtraction. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0056] All reagents used in this invention can be purchased commercially or prepared by the methods described in this invention.

[0057] General method: Remove impurities from rice bran raw materials and place them in a low-temperature rapid cooling module. Set the refrigerant temperature to -10℃ to 0℃. After approximately 10-60 minutes, the core temperature of the raw materials reaches -10℃ to -5℃. Then, transport them by conveyor belt at a rate of 5-10 kg / min to the roasting device. Set the roasting temperature to 50-70℃ and the roasting time to 10-60 minutes. Control the moisture content of the rice bran at 5-10%. Increase the temperature to 100-200℃ at a rate of 5-10℃ / min, and continue high-temperature roasting for 1- After 10 minutes, when the unique aroma of rice bran is clearly released and the moisture content is controlled below 5%, the product is transported by conveyor belt to a fluidized bed rapid cooling device at a speed of 5-10 kg / min. The refrigerant temperature is set to -40℃ to -20℃. The cooling time for each 100 kg of fragrant rice bran product is 10-60 minutes. After the product's core temperature drops below 5℃ and the moisture content is controlled below 5%, the rice bran product is obtained and weighs 28.5 kg. After vacuum packaging, it is stored in a cool place.

[0058] Example 1

[0059] Take 30 kg of cleaned rice bran raw material and put it into the low-temperature rapid cooling module. Set the refrigerant temperature to -10℃. After about 25 minutes, the core temperature of the raw material reaches -8℃. Then, it is transported by conveyor belt at a rate of 8 kg / min to the frying device. The frying temperature is set to 70℃ and the frying time is 35 minutes. The moisture content of the rice bran is controlled at 5-10%. After heating to 150℃ at a rate of 10℃ / min, continue to stir-fry at high temperature for 10 minutes until the unique aroma of rice bran is clearly released. The moisture content is controlled below 5%. Finally, it is transported by conveyor belt to the fluidized bed rapid cooling equipment at a transport speed of 10 kg / min and a refrigerant temperature set to -30℃. After 27 minutes, the core temperature of the product drops to 5℃. After taking it out, the rice bran product is obtained, weighing 28.5 kg. After vacuum packaging, it is stored in a cool place.

[0060] Example 2

[0061] Take 40 kg of cleaned rice bran raw material and put it into the rapid cooling module. Set the refrigerant temperature to -5℃. After about 30 minutes, the core temperature of the raw material reaches -4℃. Then, it is transported by conveyor belt to the frying device at a speed of 5 kg / min. The frying temperature is set to 60℃ and the frying time is 40 minutes. After the temperature is increased to 150℃ at a rate of 8℃ / min, continue to stir-fry for 5 minutes until the unique aroma of rice bran is clearly emitted and the moisture content is controlled below 5%. Finally, it is transported by conveyor belt to the fluidized bed rapid cooling equipment at a speed of 5 kg / min and a refrigerant temperature set to -20℃. After 30 minutes, the core temperature of the product drops to below 5℃ and the moisture content is controlled below 5%. After being taken out, it is the rice bran product, weighing 38.6 kg. After vacuum packaging, it is stored in a cool place.

[0062] Example 3

[0063] The difference from Example 1 is that: the raw material enters the low-temperature rapid cooling module, where the refrigerant temperature is set to -10°C. After approximately 20 minutes, the core temperature of the raw material reaches -5°C, and it is then transported to the roasting device by conveyor belt at a rate of 10 kg / min. The rest of the process is the same as in Example 1.

[0064] Example 4

[0065] The difference from Example 1 is that the rice bran is transported to the frying device by a conveyor belt at a rate of 8 kg / min, the frying temperature is set to 50°C, the frying time is 40 min, and the moisture content of the rice bran is controlled at 5-10%. The rest of the process is the same as in Example 1.

[0066] Example 5

[0067] The difference from Example 1 is that after heating to 200°C at a rate of 5°C / min, the mixture is continued to be stir-fried at high temperature for 2 minutes. The rest of the process is the same as in Example 1.

[0068] Example 6

[0069] The difference from Example 1 is that the product is transported to a fluidized bed rapid cooling device via conveyor belt at a speed of 8 kg / min, with the refrigerant temperature set to -40°C. After 20 minutes, the core temperature of the product drops to below 5°C. The rest of the process is the same as in Example 1.

[0070] Comparative Example 1

[0071] Take 30 kg of cleaned rice bran raw material and put it into the low-temperature rapid cooling module. Set the refrigerant temperature to -10℃. After about 25 minutes, the core temperature of the raw material reaches -8℃. Freeze-dry for 24 hours, and control the moisture content to below 5% to obtain the rice bran product.

[0072] Comparative Example 2

[0073] Take 30 kg of cleaned rice bran raw material and put it into the low-temperature rapid cooling module. Set the refrigerant temperature to -10℃. After about 25 minutes, the core temperature of the raw material reaches -8℃. Keep it frozen for 10 hours. The moisture content of the rice bran is controlled at 5~10%. Then, it is transported to the frying device by conveyor belt at a speed of 8 kg / min. The frying temperature is set to 70℃ and the frying time is 240 minutes. The moisture content is controlled below 5%, and the rice bran product is obtained.

[0074] Comparative Example 3

[0075] Take 30 kg of cleaned rice bran raw material and put it into the low-temperature rapid cooling module. Set the refrigerant temperature to -10℃. After about 25 minutes, the core temperature of the raw material reaches -8℃. Then, it is transported to the frying device by conveyor belt at a rate of 8 kg / min. Set the frying temperature to 70℃ and the frying time to 35 minutes. Control the moisture content of the rice bran at 5-10%. After raising the temperature to 150℃ at a rate of 10℃ / min, continue to stir-fry at high temperature for 10 minutes until the unique aroma of rice bran is clearly released. Control the moisture content to below 5% to obtain the rice bran product.

[0076] Comparative Example 4

[0077] Take 30 kg of cleaned rice bran raw material and put it into the low-temperature rapid cooling module. Set the refrigerant temperature to -10℃. After about 25 minutes, the core temperature of the raw material reaches -8℃. Then, it is transported by conveyor belt to the roasting device at a speed of 8 kg / min. The roasting temperature is set to 70℃ and the roasting time is 35 minutes. The moisture content of the rice bran is controlled at 5~10%. It is then transported by conveyor belt to the fluidized bed rapid cooling equipment at a speed of 10 kg / min and a refrigerant temperature set to -30℃. After 27 minutes, the core temperature of the product drops to 5℃. After being taken out, the rice bran product is obtained, weighing 28.5 kg. After vacuum packaging, it is stored in a cool place.

[0078] Comparative Example 5

[0079] Take 30 kg of cleaned rice bran raw material, set the frying temperature to 70℃, fry for 35 min, control the moisture content of the rice bran at 5~10%, raise the temperature to 150℃ at a rate of 10℃ / min, and continue to stir-fry at high temperature for 10 min until the unique aroma of rice bran is clearly released, and control the moisture content to below 5% to obtain the rice bran product.

[0080] Effect verification experiment 1

[0081] The peroxide value of rice bran from Example 1, Comparative Examples 1-4, and the blank group was investigated at two different temperatures over time. The blank group consisted of freshly harvested rice bran without any treatment. Storage conditions were ambient temperature (25°C). Results are shown in Table 2 and... Figure 1 As shown.

[0082] Table 2. Peroxide value (POV) results of rice bran processed by different methods at different storage temperatures.

[0083]

[0084] As shown in Table 2 and Figure 1As shown, the peroxide value of the untreated rice bran in the blank group exceeded the safety limit (risk of 0.25) after about 30 hours. The preparation processes in Comparative Examples 1-4 differed from those in Example 1, with the peroxide value reaching the safety limit as early as 60 hours and as late as 80 hours. This demonstrates that the steps in the preparation process of this application work synergistically and are indispensable. The peroxide value of the rice bran treated in Example 1 remained at a low level within 80 hours, effectively avoiding the risk of oxidative deterioration of freshly processed rice bran.

[0085] Effect verification experiment 2

[0086] To demonstrate the technical effect of the processing method provided in this application in preventing and controlling the rancidity and deterioration of rice bran, the stabilization effects of rice bran raw materials that have not been treated by the applied technology (hereinafter referred to as: rice bran raw materials), traditional rice bran processing technology (hereinafter referred to as: traditional processed rice bran slices, the process method of Comparative Example 5), and the rice bran products obtained by the process of Example 1 of this application (hereinafter referred to as: processed rice bran slices) were compared.

[0087] 1. Principle: Rice bran contains 16%–22% lipids, which can undergo hydrolysis and oxidation reactions under the action of various enzymes, generating a large number of free radicals, volatile carbonyl compounds, and free fatty acids, causing the peroxide value of the rice bran to rise rapidly. Unesterified fatty acids impart bitterness and musty taste to food, while oxidation products produce a putrid odor, severely affecting the quality of the rice bran. Therefore, changes in peroxide value during this process can quickly reflect the degree of oxidative deterioration of the rice bran, and peroxide value can serve as a key quality indicator for measuring the stability of rice bran.

[0088] 2. Experimental objective: To investigate the changes in peroxide value of rice bran raw materials and medicinal slices obtained from two different processes during long-term storage at different temperatures.

[0089] 3. Experimental Design:

[0090] 3.1 Preparation of processed rice bran samples: Take an appropriate amount of freshly harvested rice bran raw material (harvested in Yiyang, Hunan in December 2023) (hereinafter referred to as: rice bran raw material), and prepare processed rice bran samples (hereinafter referred to as: processed rice bran, Example 1) according to the traditional processing method (hereinafter referred to as: traditional processed rice bran, the process method of Comparative Example 5) and the "gradient temperature difference method".

[0091] 3.2 Constant Temperature Storage and Sampling Testing: Rice bran raw materials and two types of medicinal slices were stored in constant temperature incubators at 10℃, 25℃, and 35℃ for 80 days. Peroxide values ​​were measured on days 0, 10, 20, 30, 40, 50, 60, 70, and 80. The peroxide value (POV) change curves of the three samples under different temperature conditions were plotted (the maximum limit of peroxide value in food safety regulations is 0.25g / 100g).

[0092] Table 3. Results of Peroxide Value Changes in Rice Bran Raw Materials and Products During Storage at Different Temperatures

[0093]

[0094] 4. Results and Conclusions: The peroxide values ​​of rice bran raw materials and processed rice products stored at different temperatures are recorded in Table 3, and peroxide value change curves are plotted (e.g., ...). Figure 2 ), from the results in Table 3 above and Figure 2 It can be known that:

[0095] 4.1 The oxidation rate of rice bran is positively correlated with the temperature of the storage environment. The higher the storage temperature, the more obvious the trend of its peroxide value increases. This indicates that the storage temperature of rice bran raw materials should not be too high, and low temperature or room temperature is preferable. The first rapid cooling process proposed in this application ensures that the peroxide value of newly harvested rice bran can be maintained at a low level after immediate cooling.

[0096] 4.2 Compare the safe storage time of the three samples under the same storage temperature. For example, when stored at 35℃, the safe storage time is: processed rice bran (≥80 days) > traditional medicinal slices (less than 30 days) > rice bran medicinal materials (less than 10 days).

[0097] In summary, the gradient temperature difference method for processing rice bran mentioned in this application has a very significant effect on preventing and controlling the rancidity and deterioration of rice bran, which can better ensure the stable state of rice bran and better reflect the safety and quality stability of rice bran, and has advantages that traditional processing methods cannot match.

[0098] The method of this invention has been described through preferred embodiments. Those skilled in the art will readily be able to modify or appropriately alter and combine the methods and applications described herein within the scope, spirit, and context of this invention to implement and apply the technology of this invention. Those skilled in the art can refer to the content herein to appropriately improve process parameters. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the scope of this invention.

Claims

1. A gradient temperature difference processing method for preventing and controlling the rancidity and deterioration of rice bran slices, characterized in that, The method includes: Step 1: After the freshly harvested rice bran is screened to remove impurities, it is cooled to -10~-5℃ within 10~60 minutes under the action of a refrigerant at -10℃~0℃ to complete the low-temperature rapid cooling. Step 2: The rice bran, which has been rapidly cooled at a low temperature, is stir-fried at 50-70℃ for 10-60 minutes to complete the medium-temperature stir-frying process; Step 3: After medium-temperature stir-frying, stir-fry the rice bran at 180~200℃ for 1~10 minutes to complete the high-temperature aroma release; Step 4: After being roasted at high temperature, the rice bran is rapidly cooled to below 5℃ by a refrigerant at -40℃ to -20℃. Each 100kg of roasted rice bran product requires 10 to 60 minutes of cooling time to complete the second ultra-low temperature rapid cooling, thereby preventing the rice bran slices from becoming rancid and deteriorating.

2. The method according to claim 1, characterized in that, The low-temperature rapid cooling time is 20~30 minutes.

3. The method according to claim 1, characterized in that, The rice bran, after being rapidly cooled at low temperature, is transported to the roasting device via a conveyor belt at a speed of 5-10 kg / min.

4. The method according to claim 1, characterized in that, The medium-temperature frying process controls the moisture content of the rice bran to 5-10%.

5. The method according to claim 1, characterized in that, The medium-temperature stir-frying time is 30-40 minutes.

6. The method according to claim 1, characterized in that, After being stir-fried at medium temperature, the temperature is increased to 100-200℃ at a rate of 5-10℃ / min for high-temperature aroma extraction.

7. The method according to claim 1, characterized in that, The high-temperature roasting process controls the moisture content of the rice bran to below 5%.

8. The method according to claim 1, characterized in that, The temperature for high-temperature aroma extraction is 180~190℃.

9. The method according to claim 1, characterized in that, The rice bran, after being roasted at high temperature, is transported by conveyor belt to a fluidized bed rapid cooling device at a speed of 5-10 kg / min to ensure that the core temperature of the rice bran fluctuates within the range of 1-5℃.

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