Disclosure of Invention
In order to solve the problems, the invention provides a production method of fresh-keeping coarse cereal rice, which comprises the following specific processing method flows:
rice washing → microwave heating → water adding stirring, sealing → high pressure sterilization → product
The method comprises the following steps:
A. rice washing: adding hot water into the washed rice; B. microwave heating: heating the mixture obtained in the step A by using microwaves; C. sealing: adding coarse cereals obtained after steaming/boiling into the mixture obtained in the step B, supplementing hot coarse cereal soup, filling nitrogen, and sealing; d: and (3) high-pressure sterilization: sterilizing the sealed rice in water bath at high temperature and high pressure; in the step A, the original mass of the rice accounts for 40-98% of the sum of the original mass of the coarse cereals added in the step C and the original mass of the rice; the coarse cereals are one or a mixture of more than two of oat, buckwheat, sorghum, barley kernels and millet.
In a preferable scheme of the invention, the microwave heating in the step B has the microwave power of 3.2-6.5 kw and the time of 30-120 s.
In a preferred embodiment of the present invention, the step a specifically includes: washing rice with cold water and hot water, draining, placing into a container, and adding hot water, wherein the hot water is water with temperature of above 90 deg.C.
In a preferred embodiment of the present invention, the step C specifically includes: adding coarse cereals obtained after steaming/boiling into the mixture obtained in the step B, supplementing hot coarse cereal soup, stirring uniformly, paving rice, filling nitrogen gas and sealing, wherein the rice does not exceed the edge of the container; the hot coarse cereal soup is coarse cereal soup with the temperature of more than 90 ℃.
In a preferable scheme of the invention, in the step A, the weight ratio of the original weight of rice in the system to the weight of water after the hot water is added is 1: 0.5-1: 1.
In a preferable scheme of the invention, in the step C, the ratio of the sum of the original weight of the rice and the added coarse cereals in the system after supplementing the hot coarse cereal soup juice to the sum of the weight of the water and the coarse cereal soup juice is 1: 1.1-1: 1.5.
In a preferred embodiment of the present invention, the method for preparing coarse cereals obtained by steaming/cooking in step C comprises: steaming/boiling coarse cereals with water for 0.5-3h, filtering, discarding filtrate to obtain product, wherein the coarse cereals need to be immersed in water when boiling coarse cereals; the preparation method of the hot coarse cereal soup comprises the following steps: mixing coarse cereals with water at a mass ratio of 1:5-1:15, decocting for 0.5-3.0h, filtering, and removing filter residue to obtain hot coarse cereal soup.
In a preferable scheme of the invention, in the step D, the upper limit of the sterilization pressure is 1.5-2.0 MPa, the sterilization temperature is 113-125 ℃, and the sterilization time is 10-25 min.
In a preferred embodiment of the present invention, the container is made of a PP-EVOH composite material.
The high-pressure sterilization step adopts a water bath sterilization mode for the sealed box in a sterilization kettle, and comprises a water injection step, a temperature rising step, a heat preservation step, a hot water recovery step, a cooling water injection step, a cooling circulation step and a water drainage and exhaust step. In the sealing step, a film sealing machine can be selected, and the film sealing temperature is 150-250 ℃.
The invention also provides the fresh-keeping coarse cereal rice produced by the production method of any one of the fresh-keeping coarse cereal rice.
Advantageous effects
According to the scheme provided by the invention, microorganisms are not inhibited by adjusting pH, and the taste of the rice is not adversely affected, so that the sour taste is not covered by adding seasoning, the original rice fragrance of the rice can be kept, and the eating experience is better; according to the method provided by the invention, the traditional cooking process is not applied in the pre-cooking step of the rice, but the microwave is utilized to ensure that the rice cooking water in the container is boiled (suddenly boiled) violently under the action of the microwave, so that the starch on the surface of each grain of rice can be quickly gelatinized to form a starch gelatinization layer, the starch gelatinization layer can effectively isolate the starch, the starch in the rice is not easy to diffuse to the outside, and the rice is prevented from being adhered in the subsequent process treatment; the method does not use the traditional cooking process in the pre-cooking process, the water molecules in the pre-cooking environment do not move violently, the steam pressure is not high, the pasting layer is prevented from being damaged by the steam due to excessive contact with the steam or water in the starch pasting layer forming process, a more complete and compact pasting layer can be formed, and the internal starch is prevented from diffusing to the outside more effectively; meanwhile, the pre-cooking environment in the pre-cooking step is not high pressure, so the environment temperature of the rice grains is the boiling temperature of water, namely below 100 ℃, the processing time is short, the excessive loss of flavor substances (aldehydes, ketones, alcohols, esters, hydrocarbons and the like) in the rice caused by overhigh temperature or long processing time is avoided, and the good flavor of the rice is effectively maintained. The microwave power used in the pre-ripening step is 3.2-6.5 kw, so that the pre-ripening process can be effectively shortened, and the complete and compact degree reduction of a starch gelatinization layer caused by long-time treatment (long-time contact with water or water vapor) is avoided; in the same way, in the method, the rice washing before the pre-cooking step, the rice cooking water added before the pre-cooking step and the water supplemented after the pre-cooking are all hot water with the temperature of more than 90 ℃, so that the soaking time is greatly shortened, and the starch pasting layer is prevented from being damaged by water vapor and water; the high-temperature and high-pressure sterilization step used in the method has high temperature and short time, and can reduce the release of starch in the rice grains to the outside of the rice grains, thereby reducing the adhesion among the rice grains; the microwave heating and high-temperature high-pressure sterilization are adopted, special equipment is not needed, and the cost is low; nitrogen is filled during sealing, so that the shelf life of the product can be prolonged; the procedure of sterilizing by adopting a sterilizing kettle program is adopted, so that the sterilization is more thorough, the food sanitation is ensured, the quality guarantee period of the product is prolonged, and the product is favorably stored. In addition, the method provided by the invention uses coarse cereals as raw materials, so that the contents of dietary fibers and vitamins in the finished rice are increased. The fresh-keeping instant rice produced by the method has the advantages of low cost, convenience in use, no adhesion and conglomeration among rice grains, no slag feeling, elastic and smooth mouthfeel, complete flavor, rich nutrition, instant eating, no difference between the taste and various parameters of the fresh-keeping instant rice and the traditional boiled rice, and capability of being placed in a microwave oven to be heated for 1-2 min with medium and high fire when hot eating is needed.
Detailed Description
Example 1
A. Rice washing: washing rice with cold water and hot water, draining, placing into a container, and adding hot water; B. microwave heating: heating the mixture obtained in the step A by using microwaves; C. sealing: adding coarse cereals obtained after steaming/boiling into the mixture obtained in the step B, supplementing hot coarse cereal soup, stirring uniformly, paving rice, filling nitrogen gas and sealing, wherein the rice does not exceed the edge of the container; d: and (3) high-pressure sterilization: sterilizing the sealed rice in water bath at high temperature and high pressure; the original mass of the rice in the step A accounts for 40% of the sum of the original mass of the coarse cereals added in the step C and the original mass of the rice; the coarse cereals are oats.
And C, filling nitrogen into the rice by using a film sealing machine to seal the film, wherein the temperature of the film sealing machine is 150 ℃.
And D, adopting a water bath sterilization mode for the sealed box in the sterilization kettle, wherein the water bath sterilization mode comprises a water injection step, a temperature rising step, a heat preservation step, a hot water recovery step, a cooling water injection step, a cooling circulation step and a water drainage and exhaust step.
And B, the microwave heating in the step B has the microwave power of 3.2kw and the time of 30 s.
The hot water is water with the temperature of more than 90 ℃.
In the step A, the weight ratio of the original weight of rice in the system to the water after the hot water is added is 1: 0.5.
In the step C, the ratio of the original weight sum of the rice and the added coarse cereals in the system after supplementing the hot coarse cereal soup to the weight sum of the water and the coarse cereal soup is 1: 1.1.
The method for making the coarse cereals obtained after steaming/boiling in the step C comprises the following steps: steaming/boiling coarse cereals with water for 0.5h, filtering, discarding filtrate to obtain product, wherein the coarse cereals need to be immersed in water when boiling coarse cereals; the preparation method of the hot coarse cereal soup comprises the following steps: mixing coarse cereals with water at a mass ratio of 1:5, decocting for 0.5h, filtering, and removing filter residue to obtain hot coarse cereal soup.
In the step D, the upper limit of the sterilization pressure is 1.5MPa, the sterilization temperature is 113 ℃, the sterilization time is 10min, the cooling temperature is 40 ℃, and the cooling time is 5 min.
The container is made of a PP-EVOH composite material.
Example 2
The difference from example 1 is that: and C, the original mass of the rice in the step A accounts for 70% of the total mass of the original mass of the coarse cereals added in the step C and the original mass of the rice.
Example 3
The difference from example 1 is that:
and B, the microwave heating in the step B has the microwave power of 6.5kw and the time of 120 s.
In the step A, the weight ratio of the original weight of rice in the system to the water after the hot water is added is 1:1.
In the step C, the ratio of the original weight sum of the rice and the added coarse cereals in the system after supplementing the hot coarse cereal soup to the weight sum of the water and the coarse cereal soup is 1: 1.5.
The method for making the coarse cereals obtained after steaming/boiling in the step C comprises the following steps: steaming/boiling coarse cereals with water for 3h, filtering, discarding filtrate to obtain product, wherein the coarse cereals need to be immersed in water when boiling the coarse cereals; the preparation method of the hot coarse cereal soup comprises the following steps: mixing coarse cereals with water at a mass ratio of 1:15, decocting for 3.0h, filtering, and removing filter residue to obtain hot coarse cereal soup.
And C, filling nitrogen into the rice by using a film sealing machine to seal the film, wherein the temperature of the film sealing machine is 250 ℃.
In the step D, the upper limit of the sterilization pressure is 2.0MPa, the sterilization temperature is 125 ℃, the sterilization time is 25min, the cooling temperature is 60 ℃, and the cooling time is 10 min.
Example 4
The difference from example 2 is that:
and B, the microwave heating in the step B has the microwave power of 6.5kw and the time of 120 s.
In the step A, the weight ratio of the original weight of rice in the system to the water after the hot water is added is 1:1.
In the step C, the ratio of the original weight sum of the rice and the added coarse cereals in the system after supplementing the hot coarse cereal soup to the weight sum of the water and the coarse cereal soup is 1: 1.5.
The method for making the coarse cereals obtained after steaming/boiling in the step C comprises the following steps: steaming/boiling coarse cereals with water for 3h, filtering, discarding filtrate to obtain product, wherein the coarse cereals need to be immersed in water when boiling the coarse cereals; the preparation method of the hot coarse cereal soup comprises the following steps: mixing coarse cereals with water at a mass ratio of 1:15, decocting for 3.0h, filtering, and removing filter residue to obtain hot coarse cereal soup.
And C, filling nitrogen into the rice by using a film sealing machine to seal the film, wherein the temperature of the film sealing machine is 250 ℃.
In the step D, the upper limit of the sterilization pressure is 2.0MPa, the sterilization temperature is 125 ℃, the sterilization time is 25min, the cooling temperature is 60 ℃, and the cooling time is 10 min.
Example 5
A. Rice washing: washing rice with cold water and hot water, draining, placing into a container, and adding hot water; B. microwave heating: heating the mixture obtained in the step A by using microwaves; C. sealing: adding coarse cereals obtained after steaming/boiling into the mixture obtained in the step B, supplementing hot coarse cereal soup, stirring uniformly, paving rice, filling nitrogen gas and sealing, wherein the rice does not exceed the edge of the container; d: and (3) high-pressure sterilization: sterilizing the sealed rice in water bath at high temperature and high pressure; in the step A, the original mass of the rice accounts for 70% of the sum of the original mass of the coarse cereals added in the step C and the original mass of the rice, and the coarse cereals are oats.
And C, filling nitrogen into the rice by using a film sealing machine to seal the film, wherein the temperature of the film sealing machine is 190 ℃.
And D, adopting a water bath sterilization mode for the sealed box in the sterilization kettle, wherein the water bath sterilization mode comprises a water injection step, a temperature rising step, a heat preservation step, a hot water recovery step, a cooling water injection step, a cooling circulation step and a water drainage and exhaust step.
And B, the microwave heating in the step B has the microwave power of 4.5kw and the time of 60 s.
The hot water is water with the temperature of more than 90 ℃.
In the step A, the weight ratio of the original weight of rice in the system to the water after the hot water is added is 1: 0.75.
In the step C, the ratio of the original weight sum of the rice and the added coarse cereals in the system after supplementing the hot coarse cereal soup to the weight sum of the water and the coarse cereal soup is 1: 1.25.
The method for making the coarse cereals obtained after steaming/boiling in the step C comprises the following steps: steaming/boiling coarse cereals with water for 2h, filtering, discarding filtrate to obtain product, wherein the coarse cereals need to be immersed in water when boiling the coarse cereals; the preparation method of the hot coarse cereal soup comprises the following steps: mixing and boiling coarse cereals and water at a mass ratio of 1:10 for 2h, filtering, and removing filter residues to obtain the hot coarse cereal soup.
In the step D, the upper limit of the sterilization pressure is 1.75MPa, the sterilization temperature is 119 ℃, the sterilization time is 15min, the cooling temperature is 50 ℃, and the cooling time is 7.5 min.
The container is made of a PP-EVOH composite material.
Example 6
The difference from the example 1 is that the original mass of the rice in the step A accounts for 98 percent of the total mass of the original mass of the coarse cereals added in the step C and the original mass of the rice.
Example 7
The difference from the example 3 is that the original mass of the rice in the step A accounts for 98% of the total mass of the original mass of the coarse cereals added in the step C and the original mass of the rice.
Example 8
The difference from example 5 is that: the coarse cereals are sorghum.
Example 9
The difference from example 5 is that: the coarse cereals are a mixture of oat, buckwheat, sorghum, barley kernels and millet, and the mass ratio of the oat, the buckwheat, the sorghum, the barley kernels and the millet is 1:1:1: 1.
Comparative example 1
The production process of the common steamed rice comprises the following steps: A. rice washing: adding water into the washed rice; B. soaking: timing from the beginning of rice washing, soaking the rice in water for a certain time; C. and (3) cooking: the steamer is powered on to start steaming the rice, and the cover of the steamer is not opened in the steaming process; d: stewing: and stewing the cooked rice for a certain time. E. Sealing: and (5) filling nitrogen into the rice by using a film sealing machine to seal the film.
In the step A, the weight ratio of the original rice to the water is 1: 1.3.
In the step B, the temperature of water for soaking is about 25 ℃, and the soaking time is 30 min.
In the step C, the cooking time is 40 min.
In the step D, the stewing time is 10 min.
The phenomena of the ordinary steamed rice obtained in the comparative example 1 and the treated fresh-keeping coarse cereal rice obtained in the examples 2, 4 and 5 were observed every 24 hours (the normal rice is also sealed) and after being placed for 1d, 2d, 3d and 6 months, the microbial test was carried out on the ordinary steamed rice and the treated fresh-keeping coarse cereal rice, the total number of colonies, the coliform group bacteria and the mold were mainly used as evaluation indexes of the fresh-keeping effect, the test was repeated for 5 times for each sample, and the average value was obtained. The results are shown in tables 1 to 4. As can be seen from the data in tables 1 to 4, the fresh-keeping rice produced by the production method of the fresh-keeping rice provided by the invention has good fresh-keeping effect and slow microorganism breeding, and can prevent microbial contamination in the long-term storage process.
TABLE 1 microbiological examination of cooked rice after 1d standing
TABLE 2 microbiological examination of cooked rice after standing for 2 days
TABLE 3 microbiological examination of cooked rice after 3d standing
TABLE 4 microbiological examination of cooked rice after 6 months of storage
Comparative example 2
The production process of the high-temperature sterilized coarse cereal rice after the pressure cooking comprises the following steps: A. rice washing: adding water into the washed rice; B. soaking: timing from the beginning of rice washing, soaking the rice in water for a certain time; C. pressure cooking: the pressure cooker is connected with a power supply to start cooking rice, and the cooker cover is not required to be opened in the cooking process; D. sealing: filling nitrogen into the rice by using a film sealing machine to seal the film; e: and (3) high-pressure sterilization: the method comprises a water injection step, a temperature rising step, a heat preservation step, a hot water recovery step, a cooling water injection step, a cooling circulation step and a water discharge and exhaust step.
In the step A, the weight ratio of the original rice to the water is 1: 1.3.
In the step B, the temperature of water for soaking is about 25 ℃, and the soaking time is 30 min.
In the step C, the cooking time is 40min, and the pressure is 0.18 MPa.
In the step E, the upper limit of the pressure in the temperature and pressure raising process is 1.8MPa, the sterilization temperature is 119 ℃, the sterilization time is 15min, the cooling temperature is 50 ℃, and the cooling time is 8 min. And (5) sterilizing the sealed box in a water bath in a sterilization kettle.
The cooked rice obtained in examples 2, 4 and 5 and comparative examples 1 and 2 were subjected to sensory integration scoring, and examples 2, 4 and 5 were significantly superior in all of smell, appearance structure and palatability of cooked rice, with example 5 being the best.
TABLE 5 sensory Scoring results for cooked rice
The results of a scanning electron microscope (x 1000) performed on the rice raw material and the rice grains subjected to microwave pre-cooking in example 5 are shown in fig. 1-2, and it is obvious from the drawings that the starch on the surface of the rice subjected to microwave pre-cooking is quickly gelatinized to form a starch gelatinized layer, and the starch gelatinized layer can effectively isolate the starch, so that the starch in the rice is not easily diffused to the outside, and the rice is prevented from being adhered in the subsequent process treatment.
The results of scanning electron microscopy (x 3000) performed on the surfaces of the rice grains in the cooked rice obtained in examples 2, 4, 5 and comparative examples 1, 2 are shown in fig. 3 to 7, and it can be seen that the mesh-like pores of the fresh-keeping cooked rice of comparative example 2 are very loose, the mesh-like pores of the plain cooked rice of comparative example 1 are also comparatively loose, whereas the rice samples of examples 2, 4, 5 according to the present invention have smaller pores on the surface and a compact structure, of which example 5 is the most preferable; therefore, the method avoids the gelatinization layer from being damaged by water vapor due to excessive contact with water vapor or water in the process of forming the gelatinization layer of the starch, can form a more complete and compact gelatinization layer, and more effectively prevents the internal starch from diffusing to the outside.
TABLE 6 comparison of volatile components of cooked rice
| Rice sample
|
Aldehydes%
|
Ketones%
|
Alcohols%
|
Esters%
|
Hydrocarbons%
|
Others%
|
| Comparative example 1
|
54.82
|
7.69
|
5.26
|
4.17
|
17.83
|
10.23
|
| Comparative example 2
|
44.74
|
3.64
|
4.52
|
3.85
|
13.66
|
10.59
|
| Example 2
|
52.78
|
5.92
|
4.96
|
4.06
|
15.91
|
8.34
|
| Example 4
|
49.87
|
5.70
|
4.77
|
3.81
|
14.98
|
8.27
|
| Example 5
|
51.96
|
5.69
|
4.80
|
3.98
|
15.87
|
8.19 |
The odor components of the cooked rice are analyzed by using a headspace solid phase microextraction and GC-MC combined method, the results are shown in Table 6, and it can be seen that the contents of the volatile components such as aldehydes, ketones, alcohols and the like in the cooked rice of examples 2, 4 and 5 of the invention are obviously higher than those in comparative example 2 and are close to those in comparative example 1. The comparative example 2 shows that some small molecular substances such as alcohols and esters sensitive to heat are lost in the high-pressure processing process, but the pre-cooking environment in the pre-cooking step of the invention is not high pressure, so the environment temperature of the rice grains is the boiling temperature of water, namely below 100 ℃, and the processing time is short, thereby avoiding excessive loss of flavor substances (aldehydes, ketones, alcohols, esters, hydrocarbons and the like) in the cooked rice caused by overhigh temperature or long processing time and effectively maintaining the good flavor of the cooked rice.
TABLE 7 measurement results of physical Properties of cooked rice samples
Physical property measurement is carried out on the rice grains in the cooked rice by using a physical property instrument, the result is shown in table 7, and the hardness in the physical property measurement result of the cooked rice reflects the hardness of the rice grains; tack is the area of the recorded pattern of probe return away from the rice grain due to the sticking force of the rice grain, reflecting the tack of the rice. Among the characteristic values of the physical property instrument, the adhesiveness is better in correlation with the taste of the cooked rice, and generally, the larger the absolute value of the adhesiveness of the cooked rice is, the better the taste of the cooked rice is. As can be seen from Table 7, the hardness of examples 2, 4, 5 is slightly higher than that of comparative example 1 and lower than that of comparative example 2; the adhesion of examples 2, 4, 5 is close to that of comparative example 1, much higher than that of comparative example 2; the elasticity of examples 2, 4 and 5 is better than that of comparative examples 1 and 2; the chewiness of examples 2, 4, 5 was similar to comparative example 1, much lower than comparative example 2.