A method for processing high-nutritional value sprouted brown rice with acid-induced phytase activity

Abstract

The application discloses a processing method of high-nutrition germinated brown rice with acid-induced phytase activity, and comprises the following steps: immersing disinfected brown rice into a citric acid-vitamin C solution with a concentration of 0.5-0.7 %, and then performing low-frequency ultrasonic soaking at 25-30 DEG C for 30 min, and then cleaning the brown rice with purified water to obtain pre-soaked brown rice; immersing the pre-soaked brown rice into purified water at 35-38 DEG C, and then soaking for 6-8 h until the water absorption rate is greater than or equal to 30 %, wherein the water temperature is adjusted to 40 DEG C plus or minus 1 DEG C in the last 2 h of the soaking, and then maintained for 30 min to obtain soaked brown rice; and drying and sterilizing the soaked brown rice after germination for 24-36 h to obtain high-nutrition germinated brown rice. The application utilizes citric acid to induce and activate phytase activity in the brown rice, thereby improving the phytate degradation rate of the brown rice and the absorption rate of trace elements.

Description

Technical Field

[0001] This invention relates to the field of food processing technology, and in particular to a method for processing highly nutritious germinated brown rice with acid-induced phytase activity. Background Technology

[0002] Phytic acid, a naturally occurring anti-nutritional factor, is widely found in grains, legumes, and seeds, especially in rice, where it is typically present at levels of 7-10 g / kg. The phytic acid molecule contains multiple phosphate groups, which can form stable, insoluble complexes with divalent or polyvalent minerals such as iron, zinc, magnesium, calcium, manganese, and copper. Because the human gut lacks phytase, these complexes cannot be effectively broken down, leading to poor absorption of trace elements from food. Long-term consumption of foods high in phytic acid may cause mineral deficiencies and related health problems.

[0003] Rice, as one of the world's major food crops, has a high phytic acid content, and traditional processing methods (such as milling and cooking) have limited effect on its degradation. Studies have shown that during grain germination, endogenous phytase is activated and resynthesized, catalyzing the hydrolysis of phytic acid and releasing inositol, phosphates, and chelated minerals, thereby significantly reducing phytic acid content. This biotransformation process provides a potential pathway to improve the bioavailability of trace elements in rice. However, existing technologies for the efficient degradation of phytic acid in rice still have shortcomings, such as imprecise control of germination conditions and unstable enzyme activity, leading to limited phytic acid removal rates or affecting rice quality. Therefore, developing an efficient and controllable phytic acid degradation technology to improve the bioavailability of trace elements in rice has significant nutritional and application value. Summary of the Invention

[0004] This invention provides a method for processing highly nutritious germinated brown rice with acid-induced phytase activity to solve the technical problem of high phytic acid content in rice.

[0005] To address the aforementioned technical problems, in a first aspect, the present invention provides a method for processing highly nutritious germinated brown rice with acid-induced phytase activity, comprising the following steps:

[0006] Step 1: Soak the sterilized brown rice in a 0.5% to 0.7% citric acid-vitamin C solution, and then soak it in low-frequency ultrasonic soaking at 25℃ to 30℃ for 30 minutes. After rinsing it with purified water, you will get pre-soaked brown rice.

[0007] Step 2: Soak the pre-soaked brown rice in purified water at 35℃~38℃ for 6h~8h until the water absorption rate is ≥30%. During the last 2h of soaking in purified water, adjust the water temperature to 40℃±1℃ and maintain it for 30min to obtain soaked brown rice.

[0008] Step 3: After soaking and germinating the brown rice for 24 to 36 hours, dry and sterilize it to obtain high-nutrition germinated brown rice.

[0009] In some of the embodiments, the mass ratio of citric acid to vitamin C in the citric acid-vitamin C solution is (1-2):1.

[0010] In some of these embodiments, in step one, the mass-to-volume ratio of brown rice to citric acid-vitamin C solution is 1:(2-5).

[0011] In some of these embodiments, in step one, the operating frequency of the low-frequency ultrasound is 20kHz to 60kHz, and the output power is 30W to 100W.

[0012] In some of these embodiments, in step two, the conductivity of the purified water is ≤10 μS / cm.

[0013] In some of these embodiments, in step two, 0.01% L-cysteine ​​by mass of the purified water is added to the purified water.

[0014] In some of these embodiments, in step three, the germination environment is a temperature of 20°C to 35°C and a humidity of 70% to 90%.

[0015] In some of these embodiments, in step three, the drying parameters are low-temperature hot air drying at 40°C to 50°C until the brown rice moisture content is ≤14%.

[0016] Secondly, the present invention also provides a high-nutrition germinated brown rice, which is processed based on the above-mentioned acid-induced phytase activity high-nutrition germinated brown rice processing method.

[0017] Thirdly, the present invention also provides the application of the above-mentioned high-nutrition germinated brown rice in the preparation of rice products, wherein the rice products include cooked rice, rice cakes, rice noodles, rice cakes, rice vermicelli, rice wine, or rice milk.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] By adding a citric acid-vitamin C solution during the soaking stage to optimize the pH environment of brown rice, the activity of phytase in brown rice is activated by citric acid, thereby increasing the degradation rate of phytic acid in brown rice and reducing the phytic acid content of germinated brown rice to less than 2g / kg. Phytic acid-vitamin C promotes the formation of reduced forms of minerals such as iron, reduces the chelation effect of phytic acid and the inhibition of phytase, and improves the absorption rate of trace elements. The germination rate of brown rice is greatly improved after soaking. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] As used herein, the terms “prepared from” and “comprising” are synonymous. The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0022] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including the ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0023] Furthermore, the indefinite articles “a” and “an” preceding the elements or components of this invention do not impose any limitation on the quantity requirement (i.e., the number of times) of the elements or components. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers to the singular form.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] Example 1

[0026] A method for processing highly nutritious germinated brown rice with acid-induced phytase activity includes the following steps:

[0027] Step 1: Soak the sterilized brown rice in a 0.5% citric acid-vitamin C solution. After soaking in the solution at 25°C using low-frequency ultrasound for 30 minutes, rinse it with purified water to obtain pre-soaked brown rice. The mass ratio of citric acid to vitamin C in the citric acid-vitamin C solution is 1:1, the mass-to-volume ratio of brown rice to the citric acid-vitamin C solution is 1:2, the working frequency of the low-frequency ultrasound is 60kHz, and the output power is 100W.

[0028] Step 2: Soak the pre-soaked brown rice in purified water at 35°C with a conductivity ≤10μS / cm for 6-8 hours until the water absorption rate is ≥30%. During the last 2 hours of soaking in the purified water, adjust the water temperature to 40°C±1°C and maintain it for 30 minutes to obtain soaked brown rice. The purified water contains 0.01% L-cysteine ​​by mass.

[0029] Step 3: Germinate the soaked brown rice in a germination environment of 20℃ and 90% humidity for 36 hours, then dry it with low-temperature hot air at 40℃ until the moisture content of the brown rice is ≤14%, and sterilize it to obtain high-nutrition germinated brown rice.

[0030] Example 2

[0031] A method for processing highly nutritious germinated brown rice with acid-induced phytase activity includes the following steps:

[0032] Step 1: Soak the sterilized brown rice in a 0.6% citric acid-vitamin C solution. After soaking in the solution at 28°C using low-frequency ultrasound for 30 minutes, rinse it with purified water to obtain pre-soaked brown rice. The mass ratio of citric acid to vitamin C in the citric acid-vitamin C solution is 1.5:1, the mass-to-volume ratio of brown rice to the citric acid-vitamin C solution is 1:3, the working frequency of the low-frequency ultrasound is 40kHz, and the output power is 50W.

[0033] Step 2: Soak the pre-soaked brown rice in purified water at 36℃ with a conductivity ≤10μS / cm for 6h~8h until the water absorption rate is ≥30%. During the last 2h of soaking in purified water, adjust the water temperature to 40℃±1℃ and maintain it for 30min to obtain soaked brown rice. The purified water contains 0.01% L-cysteine ​​by mass.

[0034] Step 3: Germinate the soaked brown rice in a germination environment of 28% temperature and 85% humidity for 28 hours, then dry it with low-temperature hot air at 45℃ until the moisture content of the brown rice is ≤14%, and sterilize it to obtain high-nutrition germinated brown rice.

[0035] Example 3

[0036] A method for processing highly nutritious germinated brown rice with acid-induced phytase activity includes the following steps:

[0037] Step 1: Soak the sterilized brown rice in a 0.7% citric acid-vitamin C solution. After soaking in the solution at 30°C using low-frequency ultrasound for 30 minutes, rinse it with purified water to obtain pre-soaked brown rice. The mass ratio of citric acid to vitamin C in the citric acid-vitamin C solution is 2:1, the mass-to-volume ratio of brown rice to the citric acid-vitamin C solution is 1:5, the working frequency of the low-frequency ultrasound is 20kHz, and the output power is 30W.

[0038] Step 2: Soak the pre-soaked brown rice in purified water at 38°C with a conductivity ≤10μS / cm for 6-8 hours until the water absorption rate is ≥30%. During the last 2 hours of soaking in the purified water, adjust the water temperature to 40°C±1°C and maintain it for 30 minutes to obtain soaked brown rice. The purified water contains 0.01% L-cysteine ​​by mass.

[0039] Step 3: Germinate the soaked brown rice in a germination environment of 35% temperature and 70% humidity for 24 hours, then dry it with low-temperature hot air at 50℃ until the moisture content of the brown rice is ≤14%, and sterilize it to obtain high-nutrition germinated brown rice.

[0040] Comparative Example 1

[0041] Compared with Example 1, Comparative Example 1 used a citric acid solution of equal concentration instead of a citric acid-vitamin C solution;

[0042] Comparative Example 2

[0043] Compared with Example 1, Comparative Example 2 used a vitamin C solution of equal concentration instead of a citric acid-vitamin C solution;

[0044] Comparative Example 3

[0045] Compared to Example 1, the purified water in Comparative Example 3 did not contain added L-cysteine;

[0046] Comparative Example 4

[0047] Compared with Example 1, Comparative Example 4 used a citric acid-vitamin C solution with a mass ratio of citric acid to vitamin C of 1:2;

[0048] Comparative Example 5

[0049] Compared with Example 1, Comparative Example 5 used purified water with a conductivity of 200 μS / cm.

[0050] 1. Determination of phytic acid degradation rate

[0051] Phytic acid content was determined according to GB 5009.153-2016 "National Food Safety Standard - Determination of Phytic Acid in Food", and the phytic acid degradation rate was calculated as follows: (Phytic acid content of brown rice before germination - Phytic acid content of brown rice after germination) / Phytic acid content of brown rice before germination × 100%. The results are shown in Table 1.

[0052] Table 1. Phytic acid determination results of Examples 1 to 3 and Comparative Examples 1 to 5

[0053]

[0054] As shown in Table 1, the phytic acid degradation rate of germinated brown rice in Examples 1 to 3 reached over 80%. Compared with Comparative Example 1, which used only citric acid solution, and Comparative Example 2, which used only vitamin C solution, the citric acid-vitamin C solution used in this invention can synergistically activate phytase to degrade phytic acid in brown rice during the germination process. Comparative Example 3, which did not add L-cysteine, showed a significant decrease in phytic acid degradation rate, indicating that L-cysteine, as an antioxidant, can scavenge free radicals to protect phytase activity. Comparative Example 4, which used excessive vitamin C, showed a significant decrease in phytic acid degradation rate, indicating that excessive vitamin C disrupted the acidic synergistic effect between citric acid and vitamin C, and that high concentrations of vitamin C may undergo auto-oxidation to produce hydrogen peroxide, inhibiting phytase activity. Comparative Example 5, which used highly conductive purified water, showed an even more significant decrease in phytic acid degradation rate, indicating that highly conductive purified water inhibits phytase activity during the brown rice germination process.

[0055] 2. Iron content determination

[0056] The iron content was determined according to GB 5009.90-2016 "National Food Safety Standard - Determination of Iron in Food" and the iron retention rate was calculated as (iron content of sprouted brown rice / iron content of unsprouted brown rice) × 100%. The results are shown in Table 2.

[0057] Table 2. Results of iron content determination in Examples 1 to 3 and Comparative Examples 1 to 5.

[0058]

[0059] As shown in Table 2, Examples 1 to 3 exhibited high iron content retention rates, with Example 1 showing the highest retention rate. Compared to Example 1, the iron content retention rates of Comparative Examples 1 and 2 decreased, indicating that the absence of VC resulted in the loss of free iron in a low-solubility +3 valence form with the soaking water. The lack of citric acid led to insufficient iron chelation, making it easier for iron ions to combine with phytic acid and other substances to form insoluble compounds that were more easily lost during processing. The antioxidant properties of Comparative Example 3 prevented +2 valence iron from being oxidized to +3 valence iron. The high conductivity of the metal ions in Comparative Example 5 resulted in a high content of metal ions, which competed with iron ions for absorption sites, leading to the loss of iron through the displacement of soluble complexes.

[0060] 3. Determination of microbial contamination rate and germination rate

[0061] The microbial contamination rate was determined according to GB / T 42173-2022 "Germinated Brown Rice"; 3 kg of samples were randomly selected to determine the germination rate, and the results are shown in Table 3.

[0062] Table 3. Results of contamination levels and germination rates in Examples 1 to 3 and Comparative Examples 1 to 5.

[0063]

[0064]

[0065] As shown in Table 3, the microbial contamination rate of Examples 1 to 3 was ≤200 CFU / g, and the germination rate was greater than 95%. Compared with Example 1, the contamination rates of Comparative Examples 2, 3, and 5 were significantly higher, indicating that the weak acidity of VC could not effectively inhibit neutral-resistant bacteria, L-cysteine ​​could destroy the microbial cell membrane and achieve a bacteriostatic effect, and the high conductivity pure water contained higher inorganic salts, providing growth substrates for microorganisms; the germination rate of Comparative Example 5 was significantly lower, possibly because the high ion concentration made it difficult for the germ to absorb water, thus reducing the germination rate.

[0066] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0067] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for processing of acid-induced phytase-activity sprouted brown rice, characterized by, The method comprises the following steps: Step one, immerse the disinfected brown rice in a 0.5%-0.7% citric acid-vitamin C solution, and then immerse it in purified water at 25-30°C for 30 minutes under low-frequency ultrasonic treatment, and then rinse it with purified water to obtain pre-soaked brown rice, wherein the mass ratio of citric acid to vitamin C in the citric acid-vitamin C solution is (1-2):1; Step two, immerse the pre-soaked brown rice in 35-38°C purified water for 6-8 hours until the water absorption rate is greater than or equal to 30%, wherein the water temperature is adjusted to 40°C±1°C for 30 minutes in the last 2 hours of the immersion, to obtain soaked brown rice, wherein the conductivity of the purified water is less than or equal to 10 μS / cm, and 0.01% L-cysteine is added to the purified water based on the mass percentage of the purified water; Step three, dry and sterilize the soaked brown rice after germination for 24-36 hours to obtain germinated brown rice.

2. The acid-induced phytase activity sprouted brown rice processing method according to claim 1, wherein, In the step one, the mass-volume ratio of brown rice to citric acid-vitamin C solution is 1:(2-5).

3. The acid-induced phytase activity sprouted brown rice processing method according to claim 1, wherein, In the step one, the working frequency of the low-frequency ultrasonic treatment is 20-60 kHz, and the output power is 30-100 W.

4. The acid-induced phytase activity sprouted brown rice processing method according to claim 1, wherein, In the step three, the germination environment is at a temperature of 20-35°C and a humidity of 70-90%.

5. The acid-induced phytase activity sprouted brown rice processing method according to claim 1, wherein, In the step three, the drying parameters are low-temperature hot air drying at 40-50°C until the moisture content of the brown rice is less than or equal to 14%.

6. A germinated brown rice, characterized by, The method is based on the acid-induced phytase activity of the germinated brown rice processing method according to any one of claims 1-5.

7. Use of the sprouted brown rice according to claim 6 for the preparation of a rice product, characterized in that, The rice products include rice, rice cake, rice flour, rice cake, rice noodles, rice wine, or rice milk. The rice products include rice, rice cake, rice flour, rice cake, rice noodles, rice wine, or rice milk.

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