阅读说明：本技术 一种加工小麦粉所用小麦的杀菌方法 (Method for sterilizing wheat used for processing wheat flour ) 是由 关二旗 卢朝银 李萌萌 王天姣 卞科 毛广卿 谭银玲 张恒达 张裕蓉 张影全 孙 于 2021-08-20 设计创作，主要内容包括：本发明涉及小麦原粮杀菌技术领域,具体公开一种加工小麦粉所用小麦的杀菌方法,将小麦除杂,然后与稳定态二氧化氯溶液混合后振动着水,再静置润麦；或者,将小麦除杂,然后真空干燥、冷冻、加水一次润麦,过滤后与稳定态二氧化氯溶液混合静置二次润麦；或者,将小麦除杂,然后真空干燥、冷冻、加水一次润麦,过滤后与稳定态二氧化氯溶液混合后振动着水,再静置二次润麦,与现有的二氧化氯溶液润麦杀菌相比,本发明的小麦杀菌方法能够大幅缩短小麦的杀菌时间,而且杀菌更彻底,显著降低原粮及加工产品小麦粉,处理小麦后加工的小麦粉中菌落总数均在500CFU/g以下。(The invention relates to the technical field of wheat raw grain sterilization, and particularly discloses a sterilization method of wheat for processing wheat flour, which comprises the steps of removing impurities from wheat, mixing the wheat with a stable chlorine dioxide solution, vibrating for wetting, and standing for wetting; or removing impurities from wheat, vacuum drying, freezing, adding water, wetting wheat once, filtering, mixing with stable chlorine dioxide solution, standing, and wetting wheat twice; or, the wheat is subjected to impurity removal, then vacuum drying, freezing, wheat wetting by adding water for one time, filtering, mixing with a stable chlorine dioxide solution, vibrating for wetting, and standing for the second time for wheat wetting.)

1. A sterilization method of wheat used for processing wheat flour is characterized in that the wheat is purified, then mixed with a stable chlorine dioxide solution, vibrated to absorb water, and then kept stand for moistening the wheat;

or removing impurities from wheat, vacuum drying, freezing, adding water, wetting wheat once, filtering, mixing with stable chlorine dioxide solution, standing, and wetting wheat twice;

or removing impurities from wheat, vacuum drying, freezing, adding water, wetting, filtering, mixing with stable chlorine dioxide solution, vibrating for wetting, and standing for wetting.

2. The method of sterilizing wheat for processing wheat flour as claimed in claim 1, wherein the concentration of the stabilized chlorine dioxide solution is 5mg/L to 30mg/L, and the mass ratio of the amount of the stabilized chlorine dioxide solution added to wheat is 1:15 to 35.

3. The method of sterilizing wheat for processing wheat flour as claimed in claim 1 or 2, wherein the stable chlorine dioxide solution further contains an activator, wherein the activator is at least one of citric acid and lactic acid, and the mass ratio of the stable chlorine dioxide to the activator is 8-1: 1.

4. A method of sterilizing wheat for use in processing wheat flour as claimed in claim 1 or 2 wherein the conditioning time in the presence of the solution of chlorine dioxide in a stable state is from 3 to 8 hours.

5. The method of sterilizing wheat used for processing wheat flour as claimed in claim 1, wherein the vibration frequency of the vibration dampening is 10Hz to 110Hz, and the time of the vibration dampening of wheat is 30s to 240 s.

6. The method of claim 1, wherein the absolute pressure of the vacuum drying is 1000 to 2000Pa, the time of the vacuum drying is 2 to 3 hours, and the temperature at which the frozen wheat is stabilized is-20 to-1 ℃.

7. The method of sterilizing wheat used for processing wheat flour as claimed in claim 1, wherein the amount of water added for one-time tempering is 8 to 10wt% based on the mass of wheat and the tempering time is 60 to 90min in the two-time tempering.

8. A method of sterilizing wheat used for processing wheat flour as claimed in claim 1 or 7, wherein the temperature of the wheat wetting water for the second wetting is higher than or equal to that for the first wetting.

9. The method of claim 1, further comprising grinding the wheat after standing for wetting, mixing the ground wheat with a stable chlorine dioxide solution, and wetting the wheat with water by vibration for a second time, wherein the wetting time is 20 to 40 minutes.

Technical Field

The invention relates to the technical field of wheat raw grain sterilization, in particular to a sterilization method of wheat used for processing wheat flour.

Background

Wheat is one of three world cereal crops, and wheat flour is one of the most important food and food raw materials for human beings. China is the biggest country for wheat flour production and consumption in the world. In recent years, domestic wheat flour is consumed at about 8000 ten thousand tons per year, and more than 95% of the wheat flour is used for making various main flour foods. With the continuous improvement of the quality requirements of domestic markets on the main food products made of flour and the continuous presentation of the quality requirements of fast-paced life, new products such as semi-dry noodles, fresh wet noodles and the like appear successively, and the quality requirements on the production of raw grain wheat flour are higher and higher. In order to meet the market demand and the demand of improving the life quality of people, the food and oil society of China promulgates the first quality standard of low-bacteria wheat flour, namely T/CCOA7-2020 low-bacteria wheat flour in China. However, wheat is harvested from the field, processed in the workshop, packaged, transported, sold, processed in food and the like, and the quality of wheat flour is seriously affected along with infection and harm of microorganisms. How to effectively control the microbial quantity in the production link of wheat flour, achieve the quality standard of low-bacteria wheat flour production products and meet market demands becomes a key technical problem which needs to be solved urgently in the wheat flour milling industry at present.

Chlorine dioxide is an internationally recognized high-efficiency disinfection and sterilization agent, is also a strong oxidant which is specified in GB 2760-2014 food safety national standard food additive use standard and can be used in food raw grains and food processing, is recognized as a safe and effective sterilization mode, comprises the sterilization of gaseous chlorine dioxide or liquid chlorine dioxide solution, and is very economic. Domestic patent application CN200910091342.8 discloses a method for producing low-bacteria flour by killing microorganisms in wheat raw grains by adopting stable chlorine dioxide solution, wherein wheat is directly moistened in stable chlorine dioxide solution, so that the production cost is effectively controlled, and the possibility is provided for the actual production of low-bacteria wheat flour.

However, it is well known that microorganisms in wheat are present not only on the surface of wheat grain, but also in large quantities within wheat grain. The protection effect of the wheat grain cortex enables the part which can act when the chlorine dioxide solution is used for treating wheat to be only the wheat epidermis and difficult to permeate into the wheat grains, thereby greatly reducing the technical effectiveness of reducing microorganisms in the wheat grains. Under the common conditions, the time for wetting wheat which is needed for really achieving the effect of the wheat processing technology by adopting the chlorine dioxide solution is usually more than 24 hours, the time for wetting wheat in the patent technology related to chlorine dioxide sterilization needs 12 to 24 hours, in such a long wheat wetting process, because the moisture content in raw grains is obviously increased, and grain piles are in a closed environment, the method is very beneficial to the large breeding of microorganisms, is extremely unfavorable for controlling the quantity of the microorganisms in wheat flour, and in CN200910091342.8, the effect after 100mg/L of chlorine dioxide solution is treated for 24 hours is even slightly lower than the effect after 0.5 hour.

Disclosure of Invention

Aiming at the problems that the effectiveness of the sterilization effect of the existing chlorine dioxide solution treatment on the interior of wheat cannot be guaranteed and the treatment time is long, the invention aims to provide a wheat sterilization method for processing wheat flour so as to achieve the purposes of shortening the wheat wetting time and effectively killing microorganisms in the interior of wheat.

The invention provides the following technical scheme:

a method for sterilizing wheat for processing wheat flour comprises removing impurities from wheat, mixing with stable chlorine dioxide solution, vibrating for wetting, standing for moistening;

or removing impurities from wheat, vacuum drying, freezing, adding water, wetting wheat once, filtering, mixing with stable chlorine dioxide solution, standing, and wetting wheat twice;

or removing impurities from wheat, vacuum drying, freezing, adding water, wetting, filtering, mixing with stable chlorine dioxide solution, vibrating for wetting, and standing for wetting.

Under the common conditions, moisture is uniformly distributed in wheat grains by wheat wetting before wheat flour processing so as to meet the requirements of wheat flour, but the requirement that wheat wetting achieves the effect of a wheat processing process is a long process, generally 24 hours or even longer, because a bead core layer and an aleurone layer under a wheat seed coat have a water blocking effect, particularly the bead core layer is tightly attached to the seed coat on one hand, and is distributed in a glass state on the other hand, water is not easy to permeate at 50 ℃, and excessively high wheat wetting temperature is not beneficial to ensuring the quality of the wheat flour. Correspondingly, when wheat is moistened and sterilized by using the chlorine dioxide solution, the bead core layer and the aleurone layer under the wheat seed coat also form a barrier to the permeation of the chlorine dioxide solution, so that the wheat seed coat is sterilized, but the inner part of the wheat seed coat cannot be effectively sterilized.

The inventor finds in research that the method is beneficial to the permeation of moisture into wheat grains and is also helpful for promoting chlorine dioxide solution to permeate into the wheat grains to realize internal sterilization by combining with vibration soaking before wheat wetting, and the wheat wetting time of the chlorine dioxide solution is greatly shortened.

In the research of further widening the technical path, the wheat is subjected to vacuum drying, then is frozen, and is moistened again, so that the wheat grains are sterilized by the chlorine dioxide aqueous solution, and the wheat moistening time is greatly shortened. The inventor believes that this is because vacuum drying helps to cause the migration of inorganic salts inside the wheat kernel while evaporating water, and freezing and then wetting the wheat after drying, and the micro-expansion and pore-expanding of the wheat bran layer are realized by using water temperature, so as to promote the water to enter the inside of the wheat kernel and re-dissolve the inorganic salts, and the inorganic salts are distributed in a flowing manner again, so that more channels are opened and provided for the wetting of the wheat with the chlorine dioxide solution.

Meanwhile, the combination of freezing after vacuum drying, primary wheat wetting and chlorine dioxide solution vibration dampening can enhance the treatment effect on the basis of vibration dampening, and more advantageously, the microorganism content of the sterilized wheat after being stored for a period of time after being dried is still kept at a lower level.

Preferably, the concentration of the stable chlorine dioxide solution is 5 mg/L-30 mg/L, and the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1: 15-35. In practice, the more preferable concentration of the stable chlorine dioxide solution is 8mg/L-26mg/L, and the proper addition amount of the chlorine dioxide solution is ensured to ensure that the moisture content of the wheat after wheat wetting can be about 14 percent so as to meet the processing requirement of the wheat flour.

Preferably, the stable chlorine dioxide solution further contains an activating agent, wherein the activating agent is at least one of citric acid and lactic acid, and the mass ratio of the stable chlorine dioxide to the activating agent is 8-1: 1. The preferred mass ratio of the stable chlorine dioxide to the activating agent is 5:1, and the activating agent helps to release chlorine dioxide gas molecules.

Preferably, the wheat wetting time in the presence of the stable chlorine dioxide solution is 3-8 h. The wheat wetting time is obviously shortened, and the more preferable time is 4-6 hours.

Preferably, the vibration frequency of the vibration dampening is 10Hz to 110Hz, and the time of the vibration dampening of the wheat is 30s to 240 s. More preferably, the frequency is 20Hz to 90Hz, and the residence time is preferably 60s to 180 s.

Preferably, the absolute pressure of the vacuum drying is 1000-2000 Pa, and the stable temperature of the frozen wheat is-20 to-1 ℃. The excessive vacuum degree can reduce the rehydration rate during wheat wetting, thereby influencing the sterilization effect of the chlorine dioxide.

Preferably, in the two-time wheat wetting, the addition amount of water for one-time wheat wetting is 8-10 wt% of the mass of the wheat, and the wheat wetting time is 60-90 min. The wheat wetting time is not suitable to be too long so as to ensure that the wheat grains still have lower moisture content before secondary wheat wetting, the secondary wheat wetting is convenient, and the total moisture content after wheat wetting is controlled to meet the processing requirement of the wheat flour.

Preferably, in the method of the present invention, the temperature of the barley in the second barley-wetting is equal to or higher than that in the first barley-wetting. So as to avoid the re-shrinkage of the seed and seed coat of the wheat caused by the lower temperature during the secondary wheat wetting, and actually, the normal temperature of 15-30 ℃ is kept for the twice wheat wetting water.

The method preferably comprises the step of grinding the wheat after standing and wheat wetting into powder, mixing the powder with a stable chlorine dioxide solution, and vibrating for wetting the wheat for 20-40 min. The chlorine dioxide solution can be sterilized twice according to the processing quality requirement of the wheat flour.

The invention has the following beneficial effects:

compared with the existing wheat-moistening sterilization method by using a chlorine dioxide solution, the wheat sterilization method can greatly shorten the sterilization time of wheat, can sterilize more thoroughly, can obviously reduce raw grains and wheat flour which is a processed product, and can ensure that the total number of bacterial colonies in the wheat flour which is processed after the wheat is treated is below 500 CFU/g.

Detailed Description

The following further describes the embodiments of the present invention.

The starting materials used in the present invention are commercially available or commonly used in the art, unless otherwise specified, and the methods in the following examples are conventional in the art, unless otherwise specified.

To maintain consistency, the ambient temperatures referred to in the following examples and comparative examples were adjusted to 20. + -. 1 ℃.

Example 1

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, fine selection and wheat threshing on wheat to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 6:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 15 mg/L;

(3) adding the stable chlorine dioxide solution into the cleaned wheat through a conveying pipeline, uniformly mixing, and then conveying into a vibration dampener for vibration wheat wetting treatment, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:25, the vibration frequency of the vibration dampener is 50Hz, and the retention time is set to be 60 s;

(4) the wheat after the water treatment by vibration and the chlorine dioxide water solution are sent into a wheat wetting bin to stand and wet for 6 hours.

Example 2

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, fine selection and wheat threshing on wheat to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 3:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 8 mg/L;

(3) adding the stable chlorine dioxide solution into the cleaned wheat through a conveying pipeline, uniformly mixing, and then conveying into a vibration dampener for vibration wheat wetting treatment, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:15, the vibration frequency of the vibration dampener is 90Hz, and the retention time is set to be 180 s;

(4) the wheat after the water treatment by vibration and the chlorine dioxide water solution are sent into a wheat wetting bin to stand and wet for 8 hours.

Example 3

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, fine selection and wheat threshing on wheat to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 7:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 26 mg/L;

(3) adding the stable chlorine dioxide solution into the cleaned wheat through a conveying pipeline, uniformly mixing, and then conveying into a vibration dampener for vibration wheat wetting treatment, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:35, the vibration frequency of the vibration dampener is 110Hz, and the retention time is set to be 30 s;

(4) the wheat after the vibration water-applying treatment and the chlorine dioxide water solution are sent into a wheat wetting bin to stand and wet for 4 hours.

Example 4

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, fine selection and wheat threshing on wheat to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 8:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 30 mg/L;

(3) adding the stable chlorine dioxide solution into the cleaned wheat through a conveying pipeline, uniformly mixing, and then conveying into a vibration dampener for vibration wheat wetting treatment, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:30, the vibration frequency of the vibration dampener is 20Hz, and the retention time is set to 150 s;

(4) the wheat after the vibration water-applying treatment and the chlorine dioxide water solution are sent into a wheat wetting bin to stand and wet for 3 hours.

Example 5

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, fine selection and wheat threshing on wheat to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 5:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 5 mg/L;

(3) adding the stable chlorine dioxide solution into the cleaned wheat through a conveying pipeline, uniformly mixing, and then conveying into a vibration dampener for vibration wheat wetting treatment, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:20, the vibration frequency of the vibration dampener is 10Hz, and the retention time is set as 240 s;

(4) the wheat after the vibration water-applying treatment and the chlorine dioxide water solution are sent into a wheat wetting bin to stand and wet for 5 hours.

Example 6

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, selection and wheat threshing on wheat grains to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 6:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 15 mg/L;

(3) keeping the wheat grains for 3 hours under a vacuum environment with the absolute pressure of 1000Pa, and then cooling and freezing the wheat grains to ensure that the wheat reaches the stable temperature of-20 ℃;

(4) mixing the frozen wheat with normal-temperature tap water, wetting the wheat for 60min in a wetting bin for one time, wherein the addition amount of the wetting water is 10wt% of the mass of the wheat, and removing water;

(5) adding the normal-temperature stable chlorine dioxide solution into the wheat through a conveying pipeline, uniformly mixing, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:25, and then conveying the wheat into a wheat wetting bin for standing and secondary wheat wetting for 6 hours.

Example 7

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, selection and wheat threshing on wheat grains to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 6:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 15 mg/L;

(3) keeping wheat grains dry for 2 hours in a vacuum environment with the absolute pressure of 2000Pa, and then cooling and freezing the wheat grains to ensure that the wheat reaches the stable temperature of-1 ℃;

(4) mixing the frozen wheat with tap water at normal temperature, wetting the wheat for 90min in a wetting bin for one time, wherein the addition amount of the wetting water is 8 wt% of the mass of the wheat, and removing water;

(5) adding the normal-temperature stable chlorine dioxide solution into the wheat through a conveying pipeline, uniformly mixing, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:25, and then conveying the wheat into a wheat wetting bin for standing and secondary wheat wetting for 6 hours.

Example 8

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, selection and wheat threshing on wheat grains to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 6:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 15 mg/L;

(3) keeping the wheat grains for 2-3 hours under a vacuum environment with the absolute pressure of 1000-2000 Pa, and then cooling and freezing the wheat grains to enable the wheat to reach a stable temperature of-10 ℃;

(4) mixing the frozen wheat with normal-temperature tap water, wetting the wheat for 80min in a wetting bin for one time, wherein the addition amount of the wetting water is 9 wt% of the mass of the wheat, and removing water;

(5) adding the normal-temperature stable chlorine dioxide solution into the wheat through a conveying pipeline, uniformly mixing, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:25, and then conveying the wheat into a wheat wetting bin for standing and secondary wheat wetting for 6 hours.

Example 9

A method for sterilizing wheat used for processing wheat flour comprises the following steps:

(1) carrying out conventional air separation, screening, stone removal, fine selection and wheat threshing on wheat to remove impurities;

(2) preparing a stable chlorine dioxide solution: adding the stable chlorine dioxide and the citric acid into a closed container containing tap water one by one according to the mass ratio of 6:1, reacting for 15min, and preparing into a stable chlorine dioxide solution of 15 mg/L;

(3) keeping the wheat grains for 3 hours under a vacuum environment with the absolute pressure of 1000Pa, and then cooling and freezing the wheat grains to ensure that the wheat reaches the stable temperature of-20 ℃;

(4) mixing the frozen wheat with normal-temperature tap water, wetting the wheat for 60min in a wetting bin for one time, wherein the addition amount of the wetting water is 10wt% of the mass of the wheat, and removing water;

(5) adding the stable chlorine dioxide solution into the cleaned wheat through a conveying pipeline, uniformly mixing, and then conveying into a vibration dampener for vibration wheat wetting treatment, wherein the mass ratio of the addition amount of the stable chlorine dioxide solution to the wheat is 1:25, the vibration frequency of the vibration dampener is 50Hz, and the retention time is set to be 60 s;

(6) the wheat after the vibration water-applying treatment and the chlorine dioxide water solution are sent into a wheat wetting bin to stand and wet for 5 hours.

Comparative example 1

The difference from the embodiment 1 is that the wheat and tap water are mixed according to the mass ratio of 25:1, and then the wheat is placed in a wheat wetting bin for wetting.

Comparative example 2

The difference from the embodiment 1 is that wheat and the stable chlorine dioxide solution are mixed according to the mass ratio of 25:1 and then are placed in a wheat wetting bin for wetting, wherein the concentration of the stable chlorine dioxide solution is 15mg/L, and the mass ratio of the stable chlorine dioxide to the citric acid is 6: 1.

Comparative example 3

The difference from the embodiment 1 is that 10wt% of water is firstly added into wheat for wetting for 60min, then the wheat is filtered to remove water and then mixed with a stable chlorine dioxide solution according to the mass ratio of 25:1, and then the mixture is placed in a wetting chamber for wetting, wherein the concentration of the stable chlorine dioxide solution is 15mg/L, and the mass ratio of the stable chlorine dioxide to citric acid is 6: 1.

Comparative example 4

Except for the difference from example 6, in the step (3), wheat was frozen to a stable temperature of-20 ℃ and then dried under vacuum (temperature of 20. + -. 1 ℃) for 3 hours while maintaining an absolute pressure of 1000 Pa.

Comparative example 5

The difference from example 6 is that the wheat was dried with hot air at 40 ℃ to a similar moisture content in step (3).

Comparative example 6

The difference from example 6 is that step (4) is omitted and the frozen wheat is directly mixed with a stable chlorine dioxide solution.

Results testing

1. Test of Sterilization Effect

The wheat after wheat wetting was ground into powder by a flour mill, and then the total number of colonies in the wheat flour was measured with reference to national standard "GB 4789.2-2016 food safety national standard food microbiology test total number of colonies" and the results are shown in table 1.

TABLE 1 microbial content of wheat flour in each of the examples and comparative examples

In the above table, X hours is the length of the barley wetting time specifically described in each of examples and comparative examples, and when two barley wetting times occur, the X value is the length of the second barley wetting time. Meanwhile, in order to reflect the change of microorganisms in wheat wetting, the comparative examples 1 and 2 further prolong the wheat wetting time and measure the microorganism content under different wheat wetting time periods in a timing manner.

As shown in comparative example 1, when wheat was directly moistened with water, the increase of the microorganism content in wheat continued to increase as the moistening time increased due to the high moisture content. As shown in comparative example 2, when the wheat was directly moistened with the aqueous solution of chlorine dioxide, the microbial content decreased in a short time, but when the wheat moistening time was further prolonged, the proliferation of the microbes was enhanced and exceeded the bacteriostatic action of chlorine dioxide, so that the total microbial content was increased and the bactericidal effect of chlorine dioxide was reduced. As can be seen from the comparison between the example 1 and the comparative example 2, the bacteriostatic effect of directly moistening the wheat by using the chlorine dioxide solution is limited, and after the vibration dampening is introduced, a quite remarkable bacteriostatic effect can be achieved in a short time, and the number of the whole colonies is reduced to 0.76.

As can be seen from examples 6-8 and comparative examples 1 and 2, the bacteriostatic effect can be enhanced by adopting vacuum drying and freezing treatment, then wetting the wheat once and then directly wetting the wheat with a chlorine dioxide aqueous solution, and the number of the whole colonies is maintained at about 1.3. When used in combination with vibration dampening, this helps to further enhance the bacteriostatic effect, as shown in example 9.

As can be seen from comparison between comparative example 4 and example 6, when the wheat grains were subjected to vacuum freeze-drying, i.e., freezing and then vacuum-drying, although the bacteriostatic enhancement effect was somewhat higher than that of comparative example 2, the total amount of microorganisms was maintained at 500CFU/g or more, which is probably because the inorganic salts in the wheat grains did not migrate due to in-situ crystallization of water in the wheat grains and then vacuum sublimation during vacuum freeze-drying. It can be known from comparison of comparative example 5 and example 6 that the sterilization effect by hot air drying is inferior to that of comparative example 2, because the activity of the microorganism is enhanced by hot air treatment, the propagation of the microorganism is facilitated, the microorganism content in the wheat is increased in advance, the temperature of the wheat kernels is higher after the hot air treatment, and the wheat kernels are cooled when being moistened, so that the cortical pores shrink, and the infiltration of chlorine dioxide is not facilitated. As can be seen from comparison between comparative example 6 and example 6, the bacteriostatic effect of omitting one-time wheat wetting is reduced, and in combination with the results of comparative example 3, the inventors believe that this is probably because the steep temperature rise brought about by pre-wetting is favorable for the expansion of the pores of the wheat cortex including the bead core layer, and the inorganic salt is distributed in a flowing manner again, thereby opening and providing more channels for the chlorine dioxide solution to wet wheat.

2. Storage stability

The wheat treated in each example was dried with cold air at 25 ℃ to remove surface water and kept at a water content of 12%, then stored at 25 ℃ under ventilation for 14 days, and tested for microbial content after grinding, and the results are shown in Table 2.

TABLE 2 microbial content after storage of the examples

As can be seen from the table, the introduction of the vacuum drying, the freezing treatment, the pre-wheat wetting treatment and the wheat wetting by the chlorine dioxide solution has the advantages that although the initial sterilization effect is weaker than that of the direct vibration of the chlorine dioxide solution for water attachment, the microbial activity can be inhibited more favorably, and the microbial propagation of the wheat is limited after the wheat is stored for a period of time.

The above embodiment is only a specific implementation embodiment of the technical scheme of the invention, and the technical scheme of the invention allows further selection to be made on the basis, for example, on the basis, when the wheat flour needs higher requirements, the wheat flour can be ground and then added with a chlorine dioxide solution for secondary wheat wetting treatment.