Rice Conditioning Process and Production Method of Instant Rice

Abstract

The present disclosure discloses a rice conditioning process and a production method of instant rice, and belongs to the technical field of food processing. According to the present disclosure, rice conditioning pretreatment is realized on the basis of an instantaneous high-temperature fluidization technology, and a conditioning liquid containing compounded soft rice flour, edible oil and rice soup is prepared through a rice soup backfilling technology. A technology of rapid cooling for film forming is adopted to increase a water-retaining film on the surface of rice, so as to enhance the water-retaining property, viscoelasticity and luster of the rice. The method mainly includes the steps of rice washing and draining, conditioning, cooking, aseptic packaging and rapid cooling for film forming. According to the present disclosure, industrialized continuous production can be realized, and the obtained instant rice is sticky but not adhesive after being stored for 60 days, and has a good taste.

Claims

1. A method of rice conditioning, comprising performing an instantaneous high-temperature fluidization treatment and a conditioning liquid soaking treatment using a conditioning liquid, wherein the conditioning liquid comprises soft rice flour, edible oil and a rice soup backfilled from a cooking unit to a soaking unit.

2. The method according to claim 1, wherein the instantaneous high-temperature fluidization treatment is performed at a fluidization temperature of 130-160 C. for a fluidization time of 30-80 second (s).

3. The method according to claim 1, wherein a mass ratio of the soft rice flour to the edible oil to rice is (0.05-0.1):(0.03-0.05):1.

4. A method for producing instant rice, comprising the steps of washing and draining rice, performing a treatment on the rice by using the method according to claim 1; cooking the rice; and cooling the rice to form a film to obtain the instant rice.

5. The method according to claim 4, comprising the following steps: (1) washing rice, and draining the rice after washing; (2) conditioning: firstly performing an instantaneous high-temperature fluidization pretreatment on the rice, and then preparing a rice soup conditioning liquid containing soft rice flour and edible oil through a rice soup backfilling process, wherein the rice is soaked in a conditioning liquid for 10-20 min under 40-60 C.; (3) cooking: cooking the rice treated in step (2), taking 20%-30% of rice soup to prepare a new conditioning liquid when a temperature reaches 80-90 C., continuing cooking the rest of the rice soup for 20-30 min to obtain rice, and performing aseptic packaging; and (4) rapidly cooling the rice obtained in step (3) to form a film.

6. The method according to claim 5, wherein: the step (2) comprises the following steps: firstly performing the instantaneous high-temperature fluidization pretreatment on the rice, and then preparing the rice soup conditioning liquid containing soft rice flour and edible oil through the rice soup backfilling process, wherein a mass ratio of the soft rice flour to the edible oil to the rice is (0.05-0.1):(0.03-0.05):1, the rice is soaked in the conditioning liquid for 10-20 min under 40-60 C., and the instantaneous high-temperature fluidization treatment is performed at a fluidization temperature of 130-160 C. for the fluidization time of 30-80 s; (3) cooking: cooking the rice treated in step (2), taking 20%-30% of rice soup to prepare a new conditioning liquid when the temperature reaches 80-90 C., continuing cooking the rest of the rice soup for 20-30 min to obtain rice, and performing aseptic packaging; and step (4) comprises rapidly cooling the rice obtained in the step (3) to 0-4 C. under 80 C. to 20 C. at a rapid cooling rate of 10-14 C./min.

7. The method according to claim 5, wherein the rice soup in the step (2) is the rice soup in the cooking process of the step (3), and is obtained by the backfilling process.

8. The method according to claim 5, wherein a mass ratio of the soaked rice to water in the conditioning liquid in the step (2) is 1:(1.5-2).

9. The method according to claim 5, wherein the step (4) comprises rapidly cooling the rice to 0-4 C. under 80 C. to 20 C. at a rate of 10-14 C./min, and cooling modes for cooling comprise air cooling and cold storage cooling.

10. The method according to claim 5, wherein: step (1) comprises the following steps: rapidly washing rice with drinking water and then draining the rice; the step (2) comprises the following steps: instantaneous high-temperature fluidization pretreatment: conveying raw materials into a fluidization chamber to be subjected to a fluidization treatment for 80 s at a fluidization temperature of 130 C.; preparing conditioning liquid 1 containing soft rice flour, edible oil and water, wherein a mass ratio of the soft rice flour to the edible oil to the water is 0.05:0.05:1.5; after the conditioning liquid 1 is uniformly stirred by using a micro high-speed stirrer, soaking the rice for 20 min according to a mass ratio of the rice to water contained in the conditioning liquid 1 being 1:1.5; through a rice soup backfilling process, cooking the rice to 90 C., taking 20% of rice soup obtained by cooking to be added into a new system to replace part of water, and preparing conditioning liquid 2 at a proportion the same as that of the conditioning liquid 1, wherein a temperature of the whole system is maintained at about 50 C.; and after the conditioning liquid 2 is uniformly stirred by using the micro high-speed stirrer, soaking the rice for 20 min by using the conditioning liquid 2; the step (3) comprises the following steps: taking 20% of the rice soup for subsequent production when the cooking temperature reaches 90 C., continuing cooking for 25 min to obtain rice, and performing aseptic packaging; and step (4) comprises the following steps: in a low-temperature environment of 80 C., rapidly cooling the rice in a cold storage cooling mode until a center temperature of the rice is cooled to 0 C., wherein an average cooling rate is 13 C./min, and then placing the rice in a refrigerator of 0 C. for storage.

11. The method according to claim 5, wherein: step (1) comprises the following steps: rapidly washing rice with drinking water and then draining the rice; the step (2) comprises the following steps: instantaneous high-temperature fluidization pretreatment: conveying raw materials into a fluidization chamber to be subjected to a fluidization treatment for 30 s at a fluidization temperature of 160 C.; preparing conditioning liquid 1 containing soft rice flour, edible oil and water, wherein a mass ratio of the soft rice flour to the edible oil to the water is 0.1:0.03:2; after the conditioning liquid 1 is uniformly stirred by using a micro high-speed stirrer, soaking the rice for 15 min according to a mass ratio of the rice to water contained in the conditioning liquid 1 being 1:2; through a rice soup backfilling process, taking 30% of rice soup obtained by cooking to 85 C. to be added into a new system to replace part of water, and preparing conditioning liquid 2 at a proportion the same as that of the conditioning liquid 1, wherein a temperature of the whole system is maintained at about 60 C.; and after the conditioning liquid 2 is uniformly stirred by using the micro high-speed stirrer, soaking the rice for 15 min by using the conditioning liquid 2; the step (3) comprises the following steps:: taking 30% of the rice soup for subsequent production when a cooking temperature reaches 85 C., continuing cooking for 30 min to obtain rice, and performing aseptic packaging; and step (4) comprises the following steps: in a low-temperature environment of 70 C., rapidly cooling the rice in an air cooling mode until a center temperature of the rice is cooled to 4 C., wherein an average cooling rate is 12 C./min, and then placing the rice in a refrigerator of 4 C. for storage.

12. The method according to claim 5, wherein: step (1) comprises the following steps: rapidly washing rice with drinking water and then draining the rice; the step (2) comprises the following steps: instantaneous high-temperature fluidization pretreatment: conveying raw materials into a fluidization chamber to be subjected to a fluidization treatment for 50 s at a fluidization temperature of 140 C.; preparing conditioning liquid 1 containing soft rice flour, edible oil and water, wherein a mass ratio of the soft rice flour to the edible oil to the water is 0.08:0.04:1.8; after the conditioning liquid 1 is uniformly stirred by using a micro high-speed stirrer, soaking the rice for 10 min according to a mass ratio of the rice to water in the conditioning liquid 1 being 1:1.8; through a rice soup backfilling process, taking 25% of rice soup obtained by cooking to 80 C. to be added into a new system to replace part of water, and preparing conditioning liquid 2 at a proportion the same as that of the conditioning liquid 1, wherein a temperature of the whole system is maintained at about 40 C.; and after the conditioning liquid 2 is uniformly stirred by using the micro high-speed stirrer, soaking the rice for 10 min by using the conditioning liquid 2; the step (3) comprises the following steps: taking 25% of the rice soup for subsequent production when the cooking temperature reaches 80 C., continuing cooking for 25 min to obtain rice, and performing aseptic packaging; and step (4) comprises the following steps: in a low-temperature environment of 20 C., rapidly cooling the rice in an air cooling mode until a center temperature of the rice is cooled to 2 C., wherein an average cooling rate is 11 C./min, and then placing the rice in a refrigerator of 0 C. for storage.

13. Instant rice prepared by the method according to claim 4.

Description

BRIEF DESCRIPTION OF FIGURES

[0030] FIG. 1 is a process flow diagram of the present disclosure.

[0031] FIG. 2 shows dissolution content of starch in rice soup.

DETAILED DESCRIPTION

[0032] The following describes preferred examples of the present disclosure. It should be understood that the examples are for better explanation of the present disclosure and are not intended to limit the present disclosure.

[0033] 1. Sensory evaluation: the sensory evaluation is performed according to standards of GB/T 15682-2008 Inspection of grain and oilsMethod for sensory evaluation of paddy or rice cooking and eating quality. The details are as follows: a test is performed in a sensory evaluation laboratory and ten evaluators are selected. White porcelain plates are randomly numbered, about 50 g of reheated rice of different examples and comparative examples is taken and put into sensory cups, then the cups are put into the white porcelain plates, and the rice is eaten and evaluated while being hot. Indexes include appearance (color, luster, and integrity of rice grains), texture (viscosity, elasticity, and hardness), taste (purity and durability during chewing), and integrity (bulkiness and uniformity). The higher a sensory score, the more acceptable the rice, and sensory scores are recorded in Table 1.

[0034] 2. Texture testing: texture characteristics of samples are measured with a texture analyzer. Samples are taken at different locations and each sample is tested 12 times, with the highest and lowest values removed. Measurement parameters are set as follows: a P/25 cylindrical probe is adopted, a descending speed of the probe before measurement and a return speed of the probe after measurement are 1.0 mm/s, a testing speed is 0.5 mm/s, a compression ratio is 50%, a trigger force value is Auto-10 g, and a data acquisition rate is 200 pps.

[0035] Soft rice flour is prepared by grinding Changzhou Jintan soft rice.

Example 1

[0036] The process flow is shown in FIG. 1, and the specific steps are as follows:

[0037] (1) Rice is rapidly washed with drinking water and then drained.

[0038] (2) Conditioning: instantaneous high-temperature fluidization pretreatment: raw materials are conveyed into a fluidization chamber, and subjected to fluidization treatment for 80 s under the condition of the fluidization temperature of 130 C. A conditioning liquid 1 containing soft rice flour, edible oil and water is prepared, wherein a mass ratio of the soft rice flour to the edible oil to the water is 0.05:0.05:1.5. After the conditioning liquid 1 is uniformly stirred by using a micro high-speed stirrer, the rice is soaked for 20 min according to a mass ratio of the rice to the water contained in the conditioning liquid 1 being 1:1.5. Through a rice soup backfilling process, it can be seen from FIG. 2 that when the cooking temperature is 90 C., the amylose content and the amylopectin content in rice soup are high, with a cooking temperature range of the rice soup with higher dissolution content as a soup taking point, 20% of the rice soup obtained by cooking to 90 C. is taken (the total amount of the rice soup can be obtained by draining to serve as a reference for subsequent production), and added into a new system to replace part of water. A conditioning liquid 2 is prepared at a proportion the same as that of the conditioning liquid 1, and the temperature of the whole system is maintained at about 50 C. After the conditioning liquid 2 is uniformly stirred by using the micro high-speed stirrer, the rice is soaked for 20 min by using the conditioning liquid 2.

[0039] (3) Cooking: 20% of the rice soup is taken for subsequent production when the cooking temperature reaches 90 C.; cooking continues for 25 min to obtain rice, and the rice is aseptically packaged.

[0040] (4) Cooling for film forming: in a low-temperature environment of 80 C., the rice is rapidly cooled in a cold storage cooling mode until the center temperature of the rice is cooled to 0 C., and an average cooling rate is 13 C./min. The rice is then placed in a refrigerator of 0 C. for storage. Compared with traditional instant rice, after 60-day storage, the obtained instant rice has lower hardness than a control group after reheating, is sticky but not adhesive, and has good sensory evaluation.

Example 2

[0041] (1) Rice is rapidly washed with drinking water and then drained.

[0042] (2) Conditioning: instantaneous high-temperature fluidization pretreatment: raw materials are conveyed into a fluidization chamber, and subjected to fluidization treatment for 30 s under the condition of the fluidization temperature of 160 C. A conditioning liquid 1 containing soft rice flour, edible oil and water is prepared, wherein a mass ratio of the soft rice flour to the edible oil to the water is 0.1:0.03:2. After the conditioning liquid 1 is uniformly stirred by using a micro high-speed stirrer, the rice is soaked for 15 min according to a mass ratio of the rice to the water contained in the conditioning liquid 1 being 1:2. Through a rice soup backfilling process, 30% of rice soup obtained by cooking to 85 C. is taken (the total amount of the rice soup can be obtained by draining to serve as a reference for subsequent production), and added into a new system to replace part of water. A conditioning liquid 2 is prepared at a proportion the same as that of the conditioning liquid 1, and the temperature of the whole system is maintained at about 60 C. After the conditioning liquid 2 is uniformly stirred by using the micro high-speed stirrer, the rice is soaked for 15 min by using the conditioning liquid 2.

[0043] (3) Cooking: 30% of the rice soup is taken for subsequent production when the cooking temperature reaches 85 C.; cooking continues for 30 min to obtain rice, and the rice is aseptically packaged.

[0044] (4) Cooling for film forming: in a low-temperature environment of 70 C., the rice is rapidly cooled in an air cooling mode until the center temperature of the rice is cooled to 4 C., and an average cooling rate is 12 C./min. The rice is then placed in a refrigerator of 4 C. for storage. Compared with traditional instant rice, after 60-day storage, the obtained instant rice has lower hardness than a control group after reheating, is sticky but not adhesive, and has good sensory evaluation.

Example 3

[0045] (1) Rice is rapidly washed with drinking water and then drained.

[0046] (2) Conditioning: instantaneous high-temperature fluidization pretreatment: raw materials are conveyed into a fluidization chamber, and subjected to fluidization treatment for 50 s under the condition of the fluidization temperature of 140 C. A conditioning liquid 1 containing soft rice flour, edible oil and water is prepared, wherein a mass ratio of the soft rice flour to the edible oil to the water is 0.08:0.04:1.8, and after the conditioning liquid 1 is uniformly stirred by using a micro high-speed stirrer, the rice is soaked for 10 min according to a mass ratio of the rice to the water in the conditioning liquid 1 being 1:1.8. Through a rice soup backfilling process, 25% of rice soup obtained by cooking to 80 C. is taken (the total amount of the rice soup can be obtained by draining to serve as a reference for subsequent production), and added into a new system to replace part of water. A conditioning liquid 2 is prepared at a proportion the same as that of the conditioning liquid 1, and the temperature of the whole system is maintained at about 40 C. After the conditioning liquid 2 is uniformly stirred by using the micro high-speed stirrer, the rice is soaked for 10 min by using the conditioning liquid 2.

[0047] (3) Cooking: 25% of the rice soup is taken for subsequent production when the cooking temperature reaches 80 C.; cooking continues for 25 min to obtain rice, and the rice is aseptically packaged.

[0048] (4) Cooling for film forming: in a low-temperature environment of 20 C., the rice is rapidly cooled in an air cooling mode until the center temperature of the rice is cooled to 2 C., and an average cooling rate is 11 C./min. The rice is then placed in a refrigerator of 0 C. for storage. Compared with traditional instant rice, after 60-day storage, the obtained instant rice has lower hardness than a control group after reheating, is sticky but not adhesive, and has good sensory evaluation.

[0049] Specific experimental data is shown in Table 1. By comparing the hardness, viscosity, elasticity, chewiness and sensory scores of rice of the control group and the three examples, the instant rice obtained by the examples is lower in hardness, higher in viscosity and elasticity, better in chewiness and obviously superior in sensory evaluation than the control group.

Comparative Example 1

[0050] A preparation method of traditional instant rice includes the following steps: rice is rapidly washed with drinking water and drained; the rice is uniformly mixed with water at a mass ratio of 1:1.4, and is soaked for 15 min; and then the rice is cooked for 30 min, aseptically packaged, naturally cooled at the room temperature, stored for 60 days, and then subjected to sensory evaluation and texture characteristic analysis.

Comparative Example 2

[0051] The rice soup backfilling process in Example 1 is omitted, while other conditions or parameters are consistent with those in Example 1, and then primary instant rice is obtained. Compared with Example 1, the instant rice has poor texture performance after being stored for 60 days, which indicates that the rice soup backfilling process is more conducive to forming a smooth water-retaining film and increasing the thickness of the water-retaining film.

Comparative Example 3

[0052] The instantaneous high-temperature fluidization pretreatment in Example 1 is omitted, while other conditions or parameters are consistent with those in Example 1. Compared with Example 1, the hardness is high and viscosity and elasticity are decreased in the later storage period, which indicates that without the instantaneous high-temperature fluidization treatment, an adsorption effect of soft rice flour and edible oil on the surfaces of rice grains is poor.

Comparative Example 4

[0053] A cooling rate in a patent with the publication number of CN108522999A is adopted, specifically, rice is rapidly cooled to 0 C. at a low-temperature environment of 80 C., and an average cooling rate is 5 C./min, while other conditions or parameters are consistent with those in Example 1. Compared with Example 1, texture performance of each aspect of freshly produced instant rice is similar to that of Example 1; however, after the rice is stored for 60 days, the texture performance of the rice is poorer than that of Example 1, which indicates that rapid cooling is conductive to changing an instantaneous crystallization behavior of starch. Molecular chains of starch attached to the surfaces of rice grains are gelled before forming a crystal because of a too fast cooling speed, which can not only reduces retrogradation of starch, but also promote the starch to form a film on the surfaces of the rice grains, increase the thickness of a water-retaining film on the surface of rice, and reduce a change of texture performance after long-term storage.

Comparative Example 5

[0054] Conditions of the instantaneous high-temperature fluidization pretreatment are adjusted to the fluidization temperature of 200 C. and the fluidization time of 120 s, while other conditions or parameters are consistent with those in Example 1. Compared with Example 1, the prepared instant rice has decreased hardness and viscosity and poor taste after storage. The reasons are that the treatment temperature is too high and the treatment time is too long, which causes that the starch structure is damaged, the rice grains lose too much water, an internal compact structure is damaged, and the structure of the rice collapses after cooking. If the treatment time is too short and the treatment temperature is too low, a result of fluidization treatment may be poor and the desired effect cannot be achieved.

Comparative Example 6

[0055] An addition amount of soft rice flour is adjusted to 0.2:1, while other conditions or parameters are consistent with those in Example 1. Compared with Example 1, the prepared instant rice is scattered in grain form and appears to be incomplete in particle. Too much soft rice flour cannot be completely and effectively attached to the surfaces of the rice grains, which results in softer and over-cooked taste, and poor elasticity and chewing feeling.

Comparative Example 7

[0056] An addition amount of edible oil is adjusted to 0.1:1, while other conditions or parameters are consistent with those in Example 1. Compared with Example 1, the hardness of rice is increased, viscosity is remarkably decreased, an original taste is seriously covered by grease, and flavor deterioration is serious after storage. The reason is that if too much edible oil is added, a complex is formed by dissolved starch and lipid, which increases hydrophobicity of the starch, prevents water from entering starch granules, and limits water absorption and swelling of the starch in a gelatinization process. As a result, peak viscosity of the rice is decreased, the hardness is increased, and the viscosity is decreased. Excessive grease can easily generate a smell of grease oxidative rancidity in the storage process, which damages the original flavor of the rice. If too little edible oil is added, the effect is not significant enough.

TABLE-US-00001 TABLE 1 Texture analysis and sensory scores Sensory Sample Hardness/g Viscosity Elasticity Chewiness score Example 1 0 d 429.24 9.17.sup.d 8.64 0.97.sup.b 0.77 0.02.sup.b 315.54 26.24.sup.def 87.25 5.45.sup.a 60 d 438.36 13.45.sup.d 8.35 0.25.sup.b 0.76 0.04.sup.b 339.27 10.49.sup.de 83.05 4.58.sup.a Example 2 0 d 402.65 24.46.sup.d 8.09 0.38.sup.b 0.76 0.08.sup.b 326.33 14.76.sup.de 88.49 2.98.sup.a 60 d 428.54 49.27.sup.d 7.99 1.12.sup.ab 0.79 0.03.sup.b 379.62 11.84.sup.cd 86.37 3.06.sup.a Example 3 0 d 415.81 10.29.sup.d 8.22 0.95.sup.b 0.72 0.12.sup.ab 356.21 15.87.sup.d 85.63 2.19.sup.a 60 d 434.52 65.84.sup.d 8.56 0.73.sup.b 0.75 0.02.sup.b 342.57 28.13.sup.de 83.57 6.66.sup.a Comparative 0 d 425.28 15.22.sup.d 8.34 0.99.sup.b 0.74 0.05.sup.b 390.41 13.45.sup.c 84.79 3.24.sup.a example 1 60 d 636.25 57.21.sup.a 6.19 1.23.sup.a 0.57 0.07.sup.a 525.32 29.38.sup.a 52.21 2.56.sup.e Comparative 0 d 430.26 11.78.sup.d 8.34 0.49.sup.b 0.77 0.08.sup.b 331.66 12.39.sup.de 83.22 2.34.sup.a example 2 60 d 507.25 22.28.sup.b 6.85 1.01.sup.a 0.60 0.07.sup.a 490.28 15.53.sup.ab 58.19 3.09.sup.d Comparative 0 d 422.09 26.40.sup.d 8.66 0.48.sup.b 0.75 0.04.sup.b 327.90 10.01.sup.e 85.36 1.48.sup.a example 3 60 d 480.57 9.96.sup.c 6.45 0.97.sup.a 0.59 0.12.sup.ab 479.99 9.26.sup.b 59.47 3.17.sup.cd Comparative 0 d 419.85 15.67.sup.d 8.27 0.85.sup.b 0.78 0.03.sup.b 313.20 17.52.sup.ef 84.87 4.31.sup.a example 4 60 d 493.33 21.11.sup.c 6.39 0.64.sup.a 0.63 0.02.sup.a 493.28 14.44.sup.ab 63.28 3.78.sup.cd Comparative 0 d 417.15 12.27.sup.d 8.54 0.52.sup.b 0.75 0.03.sup.b 295.15 10.12.sup.f 75.19 2.51.sup.b example 5 60 d 396.39 19.89.sup.de 6.39 0.82.sup.a 0.56 0.06.sup.a 245.29 8.33.sup.g 53.48 4.21.sup.de Comparative 0 d 419.46 9.87.sup.d 7.86 0.73.sup.ab 0.57 0.04.sup.a 292.34 10.40.sup.f 76.34 2.48.sup.b example 6 60 d 382.47 14.42.sup.e 6.44 0.99.sup.a 0.52 0.09.sup.a 262.79 11.01.sup.g 64.59 2.26.sup.c Comparative 0 d 439.81 16.68.sup.d 8.24 0.85.sup.b 0.75 0.03.sup.b 316.33 5.27.sup.e 75.21 5.54.sup.ab example 7 60 d 509.12 10.66.sup.b 6.29 0.56.sup.a 0.68 0.05.sup.ab 359.83 20.30.sup.cd 61.18 2.27.sup.cd Note: Different lowercase letters in each column represent significant differences between values (p < 0.05).

[0057] In texture test results of rice, hardness reflects the hardness of rice grains, wherein moderate hardness is the best, and the hardness of instant rice tends to increase along with the storage time. Viscosity reflects work consumed by the viscosity of the rice grains when a test probe returns after leaving the rice grains, and depends on adhesive force, cohesive force, viscosity, viscoelasticity and the like. Elasticity reflects degrees to which the samples can recover after first compression. Chewiness simulates energy required to turn the rice grains into a steady state in which the rice grains can be swallowed, and is related to the hardness. The viscosity and elasticity have good relevance with eating quality of rice. In general, the greater absolute values of the viscosity and elasticity, the better the eating quality of rice. As shown in Table 1, compared with the comparative examples, the samples obtained in the examples have low hardness, high viscosity, high elasticity and good quality, and after the samples are stored for 60 days, texture indexes have no significant difference (p>0.05), and the change amount is less than 10%.

[0058] Although the present disclosure has been described in terms of exemplary embodiments, the exemplary embodiments are not intended to limit the present disclosure. Various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the present disclosure, and therefore the scope of protection of the present disclosure shall be defined in the appended claims.