Modified rice raw material, preparation method and application

Abstract

The invention relates to a modified rice raw material as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) drying and heat treatment: treating the rice raw material at 40-60 DEG C, and then reducing the moisture to 9% or below; (2) performing programmed temperature control heat treatment: heating, preserving heat and cooling to obtain the modified rice raw material.According to the preparation method, the rice raw material with low amylose is subjected to a specific heat treatment process, so that the surface viscosity of the prepared rice noodles is reduced, the gel strength is improved, the adding proportion of the rice raw material with low amylose in straight rice noodles can be remarkably increased, and the rice noodles with low amylose content can be prepared. The fatty acid value of the straight rice noodles is greatly reduced, and the straight rice noodles are not sticky during extrusion and are smooth in taste and rich in rice flavor.

Description

Technical Field

[0001] The present invention relates to the field of straight rice noodles, and particularly to a modified rice raw material, a preparation method and an application thereof. Background Art

[0002] The raw material of straight rice noodles mainly uses early indica rice. The growth cycle of early indica rice is short, and its processing quality and taste quality are worse than those of medium and late indica rice. However, relatively speaking, it has a high amylose content (the amylose content of some indica rice can reach more than 20%), low solubility and swelling power, small cooking loss and breakage rate of rice noodles, and the made rice noodles have good chewiness and viscoelasticity. Generally, high amylose early indica rice stored for more than 12 months is selected for making straight rice noodles. During the production process, it is generally first soaked statically to remove surface microorganisms, so that the starch and protein in the rice grains fully absorb free water, activate the internal enzyme activity of the rice grains, soften the endosperm of the rice grains, etc., and then crushed. The enzyme activity of new rice is high and the starch arrangement is unstable. Although the taste is fragrant, the gel strength still cannot meet the requirements. Therefore, the rice noodles are not strong enough, and new rice is not easy to form. Even if it is formed, it is easy to break when boiled. When processed with old rice (that is, early indica rice stored for a long time), the surface viscosity of the rice noodles decreases and the gel strength increases, which is beneficial to the processing of rice noodles and the improvement of cooking quality. However, using old rice to make straight rice noodles loses the fresh rice fragrance of the new rice itself, and the fatty acid value increases.

[0003] During the prosperous period of straight rice noodles, the raw materials of high amylose early indica rice were in short supply. On the contrary, the output of some low amylose indica rice and late indica rice was large and the utilization rate was not high. Processing and applying this part to the production of straight rice noodles would bring considerable benefits.

[0004] In the process of making rice noodles, in order to ensure the production process and reduce costs at the same time, high amylose indica rice raw materials are not completely used, and some low amylose indica rice needs to be mixed in. At present, due to the low amylose content of low amylose indica rice itself, the gel effect is poor and it is not easy to form. About 50% of corn starch, wheat starch, or a small amount of hydrophilic colloid, etc. need to be added as plasticizers for extrusion molding. Currently, the mainly added corn starch has an amylose content of more than 26% to supplement the amylose content. However, even with the addition of plasticizers to improve the processing performance, the proportion of indica rice with a low amylose content added is generally below 20%. And adding plasticizers will also affect the final taste of the rice noodles.

[0005] Hydrothermal treatment (HMT), as a physical modification method, refers to the treatment of starch granules under certain moisture content conditions (<35% moisture, w / w) for a certain period of time (15 min to 16 h) and at a certain temperature (84 °C to 120 °C). Hydrothermal treatment has an impact on starch production. Its treatment conditions are easy to control, without any chemical reagent residues, safe and harmless, belonging to a new environmentally friendly technology. Although thermal modification technologies have been reported more commonly, the modification effect on low amylose starch is not good, and it is generally believed that low amylose rice has no potential to be made into usable rice noodles.

[0006] Currently, the reports mainly focus on the hydrothermal treatment of rice starch with high amylose content. There are literature reports that hydrothermal treatment of commercial rice starch with an amylose content of 27.1% has a significant impact on the cooking and texture quality when adding it at a ratio of 50% to make rice noodles; there are also domestic reports that after superheated steam treatment of indica rice with an amylose content of 25.36%, the amylose content increases to 28.46%, thus improving the processing performance and cooking quality; in CN106509839B "A method for producing rice starch rice noodles using hydrothermal treatment technology", rice starch is treated at 100 °C to 120 °C for 1 to 8 h under the condition of 15% to 30% moisture. This patent also treats rice flour with a high amylose content, with an amylose content of 22%, and the raw material has a high moisture content and a long treatment time.

[0007] However, the literature reports mainly focus on the optimization of high amylose rice noodles and there is no significant innovation. High amylose starch itself has good congenital gel properties. Even without optimization, newly harvested high amylose rice can still be used normally after natural aging. However, late indica rice with a low amylose content (below 20%) still far from meets the requirements for making rice noodles even after aging. Without adding exogenous plasticizers, the high proportion addition of low amylose rice remains a problem.

[0008] In summary, a method for improving the application of low amylose indica rice in straight rice noodles needs to be developed. Summary of the Invention

[0009] This application discovers that by performing a specific heat treatment process on rice raw materials with low amylose content, the surface viscosity of the rice noodles decreases, the gel strength increases, the addition ratio of low amylose rice in straight rice noodles can be significantly improved, the fatty acid value of the straight rice noodles decreases significantly, there is no stickiness during wire extrusion, the taste is smooth, and the rice fragrance is strong.

[0010] The first aspect of the present invention provides a preparation method of modified rice raw materials, comprising the following steps:

[0011] (1) Dry heat treatment: After treating the rice raw material at 40 - 60°C, the moisture content is reduced to less than 9%, preferably at a temperature of 45 - 55°C, most preferably 50 - 55°C, preferably the moisture content is reduced to 5% - 9%, most preferably 7 - 9%.

[0012] (2) Program temperature-controlled heat treatment: It includes the processes of heating, holding, and cooling to obtain the modified rice raw material.

[0013] Preferably, the heating rate is 3 - 4°C / min, preferably 3 - 3.5°C / min.

[0014] The cooling rate is 1 - 1.5°C / min, preferably 1 - 1.2°C / min.

[0015] Preferably, it is cooled to below 70°C, preferably 60 - 65°C, most preferably 62 - 64°C.

[0016] The holding temperature is 115 - 130°C, preferably 118 - 125°C, preferably 120 - 121°C, and the holding time is 10 - 30 min, preferably 12 - 20 min, preferably 14 - 16 min.

[0017] In one or more embodiments, the rice raw material is selected from one or more of early indica rice, middle indica rice, and late indica rice.

[0018] In one or more embodiments, the amylose content of the rice raw material is 13 - 19 wt%, preferably 13 - 15 wt%.

[0019] In one or more embodiments, the moisture content of the rice raw material is 13 - 17 wt%, preferably 14 - 16 wt%.

[0020] In one or more embodiments, the rice raw material is an unground rice raw material. Preferably, the rice raw material is one or more of paddy, brown rice, polished rice, and broken rice.

[0021] In one or more embodiments, after step (2), there are optionally hulling and whitening steps.

[0022] In one or more embodiments, the dry heat treatment includes one or more of hot air, infrared, and microwave treatments.

[0023] The second aspect of the present invention also provides a modified rice raw material.

[0024] In one or more embodiments, the modified rice raw material is optionally hulled and polished, and finally pulverized to obtain modified rice flour with a final viscosity of 4600 - 5300 cp, preferably 4700 - 5300 cp, more preferably 4800 - 5200 cp; the retrogradation value of the modified rice flour is 2000 - 2500 cp, preferably 2200 - 2400 cp; the total soluble protein content of the modified rice flour is 3 - 5%; the amylose content of the modified rice flour is 12 - 18 wt%; the gel strength of the modified rice flour is 7000 - 8500 g, preferably 7500 - 8000 g.

[0025] The third aspect of the present invention provides a method for preparing modified rice flour, which includes subjecting any of the aforementioned modified rice raw materials to optional hulling and polishing, and finally pulverizing to obtain modified rice flour. Preferably, no soaking treatment is performed before pulverization.

[0026] The fourth aspect of the present invention provides a modified rice flour with a final viscosity of 4600 - 5300 cp, preferably 4700 - 5300 cp, more preferably 4800 - 5200 cp; the retrogradation value of the modified rice flour is 2000 - 2500 cp, preferably 2200 - 2400 cp; the total soluble protein content of the modified rice flour is 3 - 5%; the amylose content of the modified rice flour is 12 - 18 wt%; the gel strength of the modified rice flour is 7000 - 8500 g, preferably 7500 - 8000 g.

[0027] The fifth aspect of the present invention provides a raw material for straight rice noodles, which includes any of the aforementioned modified rice flours. Preferably, it further includes aged high - amylose indica rice flour with an amylose content of 20% - 26%, preferably 24% - 26%. Preferably, based on the total mass of the rice noodle raw material, the content of the modified rice flour is 90% or less, preferably 5 - 70%, more preferably 10 - 60%, still more preferably 20 - 50%, and most preferably 30 - 40%.

[0028] In one or more embodiments, the amylose content of the raw material for straight rice noodles is 17 - 24%, preferably 18 - 22%, and most preferably 18 - 21%.

[0029] The sixth aspect of the present invention provides a straight rice noodle prepared from any of the aforementioned modified rice raw materials, or modified rice flour, or raw material for straight rice noodles.

[0030] The seventh aspect of the present invention provides an application of the modified rice flour in the preparation of a raw material for straight rice noodles or straight rice noodles; preferably, in the application, based on the total weight of the raw material for straight rice noodles, the content of the modified rice flour is 90% or less, preferably 5 - 70%, more preferably 10 - 60%, still more preferably 20 - 50%, and most preferably 30 - 40%.

[0031] The present invention performs heat treatment on indica rice or brown rice with a low amylose content, so as to increase the proportion of low-amylose indica rice in the raw materials of straight rice noodles, with a short time consumption and a reduced dependence on the amylose content. In the past, the addition ratio of low-amylose rice was low, and after adding late indica rice, a higher proportion of colloid or corn starch needed to be added to act as a plasticizer. After heat treatment of low-amylose paddy or brown rice, its gel properties and gelatinization properties change significantly, which is very conducive to the formation of straight rice noodles.

[0032] The purpose of this application is not to increase the amylose content. It has low requirements for the amylose content of the mixed powder and a reduced dependence on the amylose content. Without adding or adding very little plasticizing components, it greatly increases the proportion of rice as the raw material of straight rice noodles, improves the added value, and solves the problem that the addition ratio of some indica rice in China is low and it is not suitable for making straight rice noodles.

[0033] Moreover, the treated rice raw material can be directly crushed without soaking and added as the raw material of straight rice noodles, which simplifies the processing technology and has a better effect than crushing after soaking. Detailed Description of the Invention

[0034] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form preferred technical solutions.

[0035] The following details each aspect of the present invention. Unless otherwise specified, various raw materials of the present invention can be obtained commercially or prepared according to conventional methods in the art. Unless otherwise defined or explained, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Any methods and materials similar or equivalent to the described content can be applied to the method of the present invention.

[0036] As used in the present invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0037] As used in the present invention, the term "above" or "below" means including this number.

[0038] As used in the present invention, for the sake of concise description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0039] In this text, unless otherwise specified, percentages refer to mass percentages and ratios refer to mass ratios.

[0040] The inventors of the present application found that by subjecting rice raw materials with low amylose content to a specific heat treatment process, the surface viscosity of the rice flour decreased and the gel strength increased, which could significantly increase the addition ratio of low amylose rice in straight rice noodles. The fatty acid value of the straight rice noodles decreased significantly, there was no stickiness during wire extrusion, the taste was smooth, and the rice fragrance was strong, thus completing the present invention.

[0041] Preparation method of modified rice raw material

[0042] It includes the following steps:

[0043] (1) Dry heat treatment; and

[0044] (2) Program temperature-controlled heat treatment.

[0045] In this text, dry heat treatment is to reduce the moisture of the rice raw materials to less than 9% by low-temperature heat treatment. In order to obtain good modification effects, the low-temperature heat treatment temperature should not be too high to avoid gelatinization of starch during dry heat treatment. At the same time, too low a temperature will greatly increase the dry treatment time. Therefore, the dry heat treatment temperature is 40 - 60°C, preferably 45 - 55°C, more preferably 50 - 55°C. In order to obtain good gel strength, dry heat treatment needs to reduce the moisture of the rice raw materials to less than 9%, preferably reduce the moisture to 5% - 9%, and most preferably 7 - 9%. The method of dry heat treatment is not particularly limited and can be one or several of the processing methods available in the food industry, such as hot air, infrared, and microwave treatment. In actual operation, since the moisture reduction speed of infrared and microwave is too fast and difficult to control, and the rice is prone to gelatinization, hot air drying is preferably used, and the drying time is based on reaching the moisture content requirement of the rice raw materials.

[0046] In this text, program temperature-controlled heat treatment includes the processes of heating, heat preservation, and cooling.

[0047] Furthermore, the heating rate is 3 - 4°C / min, preferably 3 - 3.5°C / min. Too fast or too slow heating rate will affect the modification effect and reduce the gel strength of the modified rice.

[0048] Furthermore, the cooling rate is 1 - 1.5°C / min, preferably 1 - 1.2°C / min. When the temperature is cooled below 70°C, the control of the cooling rate can be ended, and then the rice raw materials can be naturally cooled. Preferably, when the temperature is cooled to 60 - 65°C, most preferably 62 - 64°C, the control of the cooling rate can be ended.

[0049] Furthermore, the heat preservation temperature is 115 - 130°C, preferably 118 - 125°C, more preferably 120 - 121°C, and the heat preservation time is 10 - 30 min, preferably 12 - 20 min, more preferably 14 - 16 min.

[0050] In this article, the rice raw material refers to rice in all forms or raw materials that can form rice.

[0051] For example, the rice raw material can be paddy, brown rice, polished rice or broken rice. Since the quality of broken rice is difficult to control, there may be undercooked, insect-eaten, and diseased grains, which affect the edible quality of straight rice noodles. It is preferred that the rice raw material is whole rice, such as paddy, brown rice, or polished rice.

[0052] In this article, the variety of the rice raw material is not particularly limited and can be selected from one or more of early indica rice, middle indica rice, and late indica rice; preferably, the rice raw material has a low amylose content.

[0053] It should be noted that the amylose content of the rice raw material mentioned in this article refers to the amylose content of the polished rice obtained from the rice raw material. For example, if the rice raw material is paddy, it is the amylose content of the polished rice obtained after hulling and whitening the paddy; if the rice raw material is brown rice, it is the amylose content of the polished rice obtained after whitening the brown rice; if the rice raw material is polished rice or broken rice, directly measure the amylose content of the polished rice or broken rice. The amylose content of the rice raw material is 13 - 19 wt%, preferably 13 - 15 wt%.

[0054] In this article, there is no special limitation on the moisture content of the rice raw material. Commercially available rice raw materials can be selected. As long as the moisture is controlled to the required range through the drying heat treatment step in step (1), the moisture content of the rice raw material mentioned refers to the moisture in the form of the rice raw material during heat treatment. For example, if the raw material is paddy for heat treatment, the moisture is the moisture of the paddy before hulling; if the raw material is brown rice for heat treatment, it is the moisture of the brown rice; if the raw material is polished rice, the moisture is the moisture of the polished rice. The moisture content can be, for example, 13 - 17 wt%, preferably 14 - 16 wt%.

[0055] Furthermore, the modified rice raw materials in this article can be modified paddy, modified brown rice, modified polished rice, modified broken rice, etc.

[0056] Preferably, for the case where the rice raw material is paddy, it can also be that the modified paddy obtained by programmed temperature control heat treatment is further processed into polished rice through steps such as hulling and whitening. Compared with the case where the rice raw material is brown rice, it can also be that the modified brown rice obtained by programmed temperature control heat treatment is further processed into polished rice through steps such as whitening.

[0057] Modified rice raw material

[0058] In this article, the modified rice raw materials can be modified paddy rice, modified brown rice, modified polished rice, and modified broken rice.

[0059] For the modified paddy rice, after hulling and whitening and other steps to obtain polished rice, it is then pulverized. For the modified brown rice, after whitening and other steps to obtain polished rice, it is then pulverized. The modified polished rice and modified broken rice are directly pulverized to obtain modified rice flour. Measure its final viscosity to be 4600 - 5300 cp, preferably 4700 - 5300 cp, more preferably 4800 - 5200 cp; the retrogradation value of the modified rice flour is 2000 - 2500 cp, preferably 2200 - 2400 cp; the total soluble protein content of the modified rice flour is 3 - 5%; the amylose content of the modified rice flour is 12 - 18 wt%; the gel strength of the modified rice flour is 7000 - 8500 g, preferably 7500 - 8000 g.

[0060] Preparation method of modified rice flour

[0061] Subject any one of the aforementioned modified rice raw materials to optional hulling and whitening, and finally pulverize to obtain modified rice flour. For example, for the modified paddy rice, after hulling and whitening and other steps to obtain polished rice, it is then pulverized. For the modified brown rice, after whitening and other steps to obtain polished rice, it is then pulverized. The modified polished rice and modified broken rice are directly pulverized to obtain modified rice flour.

[0062] In the conventional rice flour preparation process, the rice needs to be soaked before pulverization. For example, it is taken out after soaking in water for more than 1 h, preferably taken out after soaking for 1 - 5 h, more preferably taken out after soaking for 3 h, filtered with a gauze to remove water, and dried in a ventilated place until there is no free water on the surface and the rice can be scattered naturally. For example, it is dried for more than 0.5 h, preferably for more than 1 h, such as 1.5 h. At this time, the moisture content is 20 - 30%, preferably 23% - 25%.

[0063] In this article, it is preferred not to perform soaking treatment before pulverization.

[0064] Modified rice flour

[0065] The final viscosity of the modified rice flour is 4600 - 5300 cp, preferably 4700 - 5300 cp, more preferably 4800 - 5200 cp; the retrogradation value of the modified rice flour is 2000 - 2500 cp, preferably 2200 - 2400 cp; the total soluble protein content of the modified rice flour is 3 - 5%; the amylose content of the modified rice flour is 12 - 18 wt%; the gel strength of the modified rice flour is 7000 - 8500 g, preferably 7500 - 8000 g.

[0066] Straight rice noodle raw material

[0067] The raw materials for straight rice noodles include any of the aforementioned modified rice flours. The modified rice flour can be used alone as a raw material to prepare straight rice noodles, or can be mixed with other common raw materials for preparing straight rice noodles in this field. For example, it can include high amylose indica rice flour, and can also include other cereal flours with a high amylose content, such as corn starch and wheat starch. Or a small amount of hydrophilic colloid can be added as a plasticizer for extrusion molding.

[0068] Preferably, the raw materials for straight rice noodles also include aged high amylose indica rice flour with an amylose content of 20% - 26%, preferably 24% - 26% of aged high amylose indica rice flour. Based on the total mass of the rice noodle raw materials, the content of the modified rice flour is below 90%, preferably below 70%, more preferably below 60%, still more preferably below 50%. The content of the modified rice flour is above 5%, preferably above 10%, more preferably above 20%, and most preferably 30 - 40%. Preferably, the content of high amylose rice flour is above 10%, preferably above 30%, more preferably above 50%, and most preferably 60 - 70%.

[0069] Preferably, the amylose content of the mixed raw materials for straight rice noodles is 17 - 24%, preferably 18 - 22%, and most preferably 18 - 21%.

[0070] Straight rice noodles

[0071] Straight rice noodles are prepared from modified rice raw materials, or modified rice flour, or raw materials for straight rice noodles through a conventional extrusion process. Based on the total weight of the raw materials for straight rice noodles, the content of the modified rice flour is below 90%, preferably below 70%, more preferably below 60%, still more preferably below 50%. The content of the modified rice flour is above 5%, preferably above 10%, more preferably above 20%, and most preferably 30 - 40%.

[0072] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

[0073] In the following embodiments and comparative examples of the present invention, the detection methods used are as follows:

[0074] 1. Moisture determination: Refer to GB5009.3–2016 National Food Safety Standard Determination of Moisture in Foods.

[0075] 2. Amylose content determination: Refer to GB / T 15683-2008 Determination of Amylose Content in Rice.

[0076] 3. Gelatinization characteristics of rice flour:

[0077] Using a rapid viscometer, set the water content to 14%, the sample amount to 3.50 g, and 25 mL of distilled water. During the measurement, the temperature inside the tank changed as follows: maintained at 50 °C for 1 min, rose to 95 °C at a rate of 12 °C / min (3.75 min), maintained at 95 °C for 2.5 min, dropped to 50 °C (3.75 min), and maintained at 50 °C for 1.4 min. The starting rotational speed of the stirrer was 960 r / min for the first 10 s and then maintained at 160 r / min.

[0078] 4. Determination of total soluble protein.

[0079] Extract albumin, globulin, gliadin, and glutelin with water, 0.5 mol / L NaCl, 70% ethanol, and 0.1 mol / L KOH respectively, and use the Coomassie brilliant blue colorimetric method for determination to calculate the total content of the 4 soluble proteins.

[0080] 5. Preparation and determination of rice flour frozen gel

[0081] Accurately weigh 5 g of rice flour (dry basis) and 15 g of water. After mixing and stirring evenly, place it in a boiling water bath (timing for 15 min), stir while heating. Stop stirring when the starch granules are gelatinized and the system gradually becomes viscous, continue heating until the timing ends, take it out and refrigerate and age at 4 °C, and determine the texture properties. The probe model of the texture analyzer: P / 100; the parameters of the compression mode are the running speed before testing 1 mm / s; the testing speed 1 mm / s; the return speed after testing 5 mm / s; the deformation amount 35%; the trigger force 10 g; the pressing interval 5 s.

[0082] 6. Determination of the surface viscosity of the mixed powder

[0083] Use the gel at the end of the rice paste gelatinization property experiment for the surface viscosity experiment. Probe model: P / 1S; the parameters of the compression mode are the running speed before testing 1.5 mm / s; the testing speed 2 mm / s; the return speed after testing 10 mm / s; the pressing distance 5 mm; the trigger force 2.5 g

[0084] 7. Determination of the spitting rate: Weigh 10 g of the finished rice flour, pour 250 mL of distilled water into the pot, heat it to boiling with an induction cooker; put in the sample and time for 5 min, prevent bubbles from sticking to the pot lid. After the timing ends, open the lid and pick up all the rice flour with chopsticks, pour the cooking water into a beaker, take 1 / 10 of it with an aluminum box and bake it in a drying oven at 130 °C for 40 min, and calculate the percentage of the dried solid matter in the total weight of the rice flour.

[0085] 8. Preparation process of straight rice noodles: Rice soaking (some heat-treated indica rice is not soaked) → Crushing → Premixing of raw materials → Extruding silk → Aging and steaming of powder → Loosening silk → Drying → Cutting powder → Finished product

[0086] Example 1

[0087] Late indica rice paddy with an amylose content of 13.8% and an original moisture content of 14.4% was dried in a hot air oven at 55°C for 5 h. After that, the moisture content of the paddy decreased to 7.23%. Hot steam was introduced into the heating auxiliary container in a programmed manner, and the temperature was raised to 121°C at a rate of 3.5°C / min and maintained for 15 min. Then, the temperature was decreased to 64°C at a rate of 1.2°C, and the moisture content increased to 9.53%. The treated paddy was obtained, hulled, milled white, and pulverized to 80 mesh without soaking to obtain treated indica rice flour. 50% of the treated indica rice flour was added and mixed with early indica rice flour with an amylose content of 26% that had been aged, soaked, and pulverized. After mixing evenly, the retrogradation value of the mixed indica rice flour increased by 43%, and the final viscosity increased by 43%. Moreover, the amylose content of the mixed indica rice flour was 19.1%. It was cooked and extruded into straight rice noodles.

[0088] Example 2

[0089] Brown rice of late indica rice with an amylose content of 13.8% and an original moisture content of 15.6% was dried in an oven at 55°C for 5 h. After that, the moisture content was 8.46%. Hot steam was introduced in a programmed manner, and the temperature was raised to 125°C at a rate of 3°C / min and maintained for 12 min. Then, the temperature was decreased to 64°C at a rate of 1°C, and the moisture content increased to 10.97% after the programmed temperature increase. After milling white, it was directly pulverized to 80 mesh without soaking to obtain treated indica rice flour. The treated rice flour was added at a ratio of 50% and mixed with early indica rice flour with an amylose content of 26% that had been aged, soaked, and pulverized. The amylose content of the mixed flour was 19.5%. It was cooked and extruded into straight rice noodles.

[0090] Example 3

[0091] Late indica rice paddy had an amylose content of 13.8% and an original moisture content of 14.4%. After drying in an oven at 55°C for 4 - 5 h, the moisture content of the paddy decreased to 7.23%. Hot steam was introduced in a programmed manner, and the temperature was raised to 118°C at a rate of 3.5°C / min and maintained for 20 min. Then, the temperature was decreased to 60°C at a rate of 1.5°C, and the moisture content increased to 9.53%. The treated paddy was obtained, hulled, milled white, and pulverized to 80 mesh without soaking to obtain treated indica rice flour. The treated rice flour was directly added at a ratio of 50% and mixed with early indica rice flour with an amylose content of 24% that had been aged, soaked, and pulverized. The amylose content after mixing was 18.1%. It was cooked and extruded into straight rice noodles. The effects were the same as those in Example 1.

[0092] Example 4

[0093] Late indica rice with an amylose content of 18.8% and an original moisture content of 13.4% was dried in a hot air oven at 45°C for 8 hours. After that, the moisture content of the rice decreased to 7.53%. Then, hot steam was introduced, and the temperature was raised to 121°C at a rate of 4°C / min and maintained for 15 minutes. Subsequently, the temperature was decreased to 65°C at a rate of 1.2°C, and the moisture content increased to 9.53%. The treated rice was obtained, dehulled, polished, and ground without soaking to 80 mesh to obtain treated indica rice flour. It was mixed with 30% of early indica rice flour with an amylose content of 20% that had been aged, soaked, and ground, and the mixture was evenly blended to obtain mixed indica rice flour with an amylose content of 19.4%. The mixed indica rice flour was cooked and extruded into straight rice noodles.

[0094] Example 5

[0095] Late indica rice with an amylose content of 13.8% was dehulled to become brown rice with an original moisture content of 14.9%. The brown rice was dried in a hot air oven at 55°C for 5 hours, and the moisture content decreased to 7.4%. Then, hot steam was introduced in a programmed manner, and the temperature was raised to 121°C at a rate of 3.5°C / min and maintained for 15 minutes. Subsequently, the temperature was decreased to 64°C at a rate of 1.2°C, and the moisture content increased to 9.85%. After polishing and grinding without soaking to 80 mesh, treated indica rice flour was obtained. It was mixed with 40% of early indica rice flour with an amylose content of 26% that had been aged, soaked, and ground, and the mixture was evenly blended to obtain mixed indica rice flour with an amylose content of 21%. The mixed indica rice flour was cooked and extruded into straight rice noodles. The resulting effect was the same as that of Example 1.

[0096] Example 6

[0097] Late indica rice with an amylose content of 13.8% was husked and polished to obtain polished rice with an original moisture content of 14.4%. The polished rice was dried in a hot air oven at 55°C for 5 hours, and the moisture content of the rice decreased to 7.23%. Then, hot steam was introduced in a programmed manner, and the temperature was raised to 121°C at a rate of 3.5°C / min and maintained for 15 minutes. Subsequently, the temperature was decreased to 64°C at a rate of 1.2°C, and the moisture content increased to 9.53%. It was ground without soaking to 80 mesh to obtain treated indica rice flour. The addition ratio was 50%, and it was mixed with indica rice flour with an amylose content of 26% that had been aged, soaked, and ground. The mixture was evenly blended to obtain mixed indica rice flour with an amylose content of 20%. The mixed indica rice flour was cooked and extruded into straight rice noodles.

[0098] Example 7

[0099] The amylose content of late indica rice is 13.8%, and the original moisture content is 14.4%. After drying in an oven at 55°C for 5 hours, the moisture content of the rice drops to 7.23%. After programmed temperature increase treatment, it rises to 9.53%. The treated rice is obtained, hulled and polished to get polished rice. The polished rice is soaked for 3.5 hours, the surface free water is wiped off and dried, and then ground to 80 mesh to obtain treated indica rice flour. The treated rice flour is directly added, and according to the dry basis addition ratio of 50%, it is mixed with early indica rice flour with an amylose content of 24% that has been aged, soaked and ground, and then cooked and extruded to prepare straight rice noodles.

[0100] Example 8

[0101] The amylose content of late indica rice is 13.8%, and the original moisture content is 14.4%. After drying in an oven at 55°C for 5 hours, the moisture content of the rice drops to 7.23%. It is heated to 121°C at a rate of 3.5°C / min and held for 15 minutes. After programmed temperature increase and heat preservation, the rice is quickly cooled to room temperature with low-temperature cold air to obtain treated rice. The treated rice is hulled, polished and directly ground to 80 mesh to obtain treated indica rice flour. The treated indica rice flour is directly added, and the addition ratio is 50%. It is mixed with early indica rice flour with an amylose content of 26% that has been aged, soaked and ground to obtain mixed indica rice flour, and then cooked and extruded to prepare straight rice noodles.

[0102] Control Example 1

[0103] The amylose content of late indica rice is 13.8%, and the original moisture content is 14.4%. Without drying, hot steam is introduced into the heating auxiliary container programmatically. It is heated to 121°C at a rate of 3.5°C / min and held for 15 minutes, and then cooled to 64°C at a rate of 1.2°C, and the moisture content rises to 17.83%. After programmed heat treatment, the treated rice is obtained. The treated rice is hulled, polished and ground to 80 mesh without soaking to obtain treated indica rice flour. The treated indica rice flour is directly added, and the addition ratio is 50%. It is mixed with early indica rice flour with an amylose content of 26% that has been aged, soaked and ground to obtain mixed indica rice flour. The amylose content of the mixed indica rice flour is about 20%, and then cooked and extruded to prepare straight rice noodles.

[0104] Control Example 2

[0105] The amylose content of late indica rice is 13.8%, and the original moisture content is 14.4%. After drying in an oven at 55°C for 5 hours, the moisture content of the rice decreases to 7.23%. Without using programmed temperature rise, a large amount of steam is quickly passed through to raise the temperature to 121°C and treated for 15 minutes, and then the temperature is decreased step by step to obtain the treated rice. After hulling, whitening, and directly pulverizing to 80 mesh, the treated indica rice flour is obtained. The treated indica rice flour is directly added at an addition ratio of 50% and mixed with early indica rice flour with an amylose content of 26% after aging, soaking, and pulverization to obtain the mixed indica rice flour. The amylose content of the mixed indica rice flour is 20%, and it is cooked and extruded to prepare straight rice noodles.

[0106] Control Example 3

[0107] The amylose content of late indica rice with low amylose is 13.8%, and the original moisture content is 14.4%. It is heated to 121°C at a rate of 3.5°C / min, maintained for 15 minutes, and then cooled to 64°C at a rate of 1.2°C. After programmed heat treatment, the moisture content reaches 17.5%, and then dried in an oven at 55°C for 6 hours, and the moisture content is reduced to 8.5%. The treated rice is obtained, and after hulling, whitening, and directly pulverizing to 80 mesh, the treated indica rice flour is obtained. The treated indica rice flour is directly added at an addition ratio of 50% and mixed with early indica rice flour with an amylose content of 26% after aging, soaking, and pulverization to obtain the mixed indica rice flour.

[0108] Control Example 4

[0109] Late indica rice with an amylose content of 13.8% is hulled, whitened, and pulverized to 80 mesh to obtain indica rice flour, and the original moisture content is 14.4%. After drying in an oven at 55°C for 5 hours, the moisture content of the indica rice flour is reduced to 7.1%, and it is heated to 121°C at a rate of 3.5°C

[0110] / min, maintained for 15 minutes, and then cooled to 64°C at a rate of 1.2°C. After programmed temperature control heat treatment, the moisture content rises to 10.43% to obtain the treated indica rice flour. The treated indica rice flour is directly added at an addition ratio of 50% and mixed with indica rice flour with an amylose content of 26% after aging, soaking, and pulverization, and mixed evenly to obtain the mixed indica rice flour. The amylose content of the mixed indica rice flour is 20%, and it is cooked and extruded into straight rice noodles.

[0111] Control Example 5

[0112] Using early indica rice with a high amylose content of 23.93% that has not been aged, with an original moisture content of 13.34%, after drying in an oven at 55°C for 5 hours, the moisture content of the rice grains is reduced to 8.3%. Hot steam is introduced procedurally, the temperature is raised to 125°C at a rate of 3°C / min and maintained for 12 minutes, and then the temperature is lowered to 64°C at a rate of 1°C. After the programmed heat treatment, the moisture content increases to 10.73%. The treated rice grains are obtained, hulled, polished, and pulverized to 80 mesh without soaking to obtain treated indica rice flour. The treated indica rice flour is directly added at an addition ratio of 50% and mixed with early indica rice flour with an amylose content of 26% that has been aged, soaked, and pulverized to obtain mixed indica rice flour, which is cooked and extruded to prepare straight rice noodles.

[0113] Control Example 6

[0114] Prepared by blending untreated late indica rice flour with an amylose content of 13.8% and untreated aged early indica rice flour with an amylose content of 23.93% at a mass ratio of 1:1.

[0115] Table 1 Gelatinization characteristics of treated indica rice flour

[0116]

[0117]

[0118] Table 2 Detection values of total soluble protein in modified indica rice flour

[0119]

[0120] Table 3 Amylose content of modified indica rice flour

[0121]

[0122] Table 4 Gel strength of modified indica rice flour

[0123]

[0124] Table 5 Gel surface viscosity & gel strength of mixed rice flour

[0125]

[0126] Table 6 Spit slurry rate of straight rice noodles

[0127]

[0128] From the above experimental data, it can be seen that after heat treatment in the embodiments of the present application, the final viscosity and retrogradation value of indica rice flour increase significantly, the gel strength increases significantly, the surface viscosity decreases significantly, the amylose content does not increase, and there is a very small decrease in the amylose content in the embodiments. The indica rice flour is evenly mixed to obtain a mixed indica rice flour. The retrogradation value and final viscosity of the mixed indica rice flour increase significantly, the gel strength is good, the surface viscosity is low, and the amylose content of the mixed indica rice flour is less than 21%. It is cooked and extruded to prepare straight rice noodles. After the rice noodles are extruded during the extrusion process, the surface does not stick, the noodles do not break, it is easy to age, and there is a strong fragrance of cooked rice when chewing.

[0129] Compared with Example 6, the effect of Example 7 is slightly worse. It is speculated that soaking causes partial rebound of the properties of the modified rice, resulting in a worse result.

[0130] In Comparative Example 1, no drying treatment was carried out. In Comparative Example 2, the heating rate was not controlled. In Comparative Example 3, the temperature was programmed to rise first and then dried. The final viscosity and retrogradation value of the obtained indica rice flour changed little. The gel strength and surface viscosity of the gel formed had no obvious change compared with the untreated indica rice flour. During the extrusion process, the adhesion phenomenon was serious, the aging and retrogradation effect was poor, and the bleeding rate was high after drying.

[0131] In Comparative Example 4, the indica rice flour was directly treated. After treatment, the final viscosity and retrogradation value of the indica rice flour both increased to a certain extent. The gel strength and surface viscosity of the formed mixed gel were slightly improved, but far from meeting the requirements of the rice noodle raw material.

[0132] In Control Example 5, the paddy with a high amylose content was treated. After treatment, there was no increase in the final viscosity and retrogradation value of the indica rice flour, but instead a decreasing trend. In particular, the properties of the formed gel became worse, the gel strength decreased slightly, and the gel properties of the mixed rice flour also decreased.

Claims

1. A preparation method of a modified rice raw material, characterized in that, The method includes the following steps: (1) Dry heat treatment: The rice raw material is treated at 40 - 60°C to reduce the moisture content to below 9%, preferably at 45 - 55°C, most preferably at 50 - 55°C, and preferably the moisture content is reduced to 5% - 9%, most preferably 7% - 9%. (2) Program temperature-controlled heat treatment: including the processes of heating, holding, and cooling to obtain the modified rice raw material. Preferably, the heating rate is 3 - 4°C / min, preferably 3 - 3.5°C / min. Preferably, the cooling rate is 1 - 1.5°C / min, preferably 1 - 1.2°C / min. Preferably, it is cooled to below 70°C, preferably 60 - 65°C, most preferably 62 - 64°C. Preferably, the holding temperature is 115 - 130°C, preferably 118 - 125°C, preferably 120 - 121°C, and the holding time is 10 - 30 min, preferably 12 - 20 min, preferably 14 - 16 min.

2. The method according to claim 1, characterized in that, It also includes at least one of the following features: (1) The rice raw material is selected from one or more of early indica rice, middle indica rice, and late indica rice. (2) The amylose content of the rice raw material is 13 - 19 wt%, preferably 13 - 15 wt%. (3) The moisture content of the rice raw material is 13 - 17 wt%, preferably 14 - 16 wt%. (4) The rice raw material is an unground rice raw material. Preferably, the rice raw material is one or more of paddy, brown rice, polished rice, and broken rice. (5) Optionally, hulling and whitening steps are further included after step (2). (6) The dry heat treatment includes one or more of hot air, infrared, and microwave treatments.

3. The modified rice raw material obtained by the method according to claim 1 or 2.

4. A modified rice raw material, characterized in that, The modified rice raw material is optionally hulled and whitened, and finally ground to obtain the modified rice flour with a final viscosity of 4600 - 5300 cp, preferably 4700 - 5300 cp, more preferably 4800 - 5200 cp; the retrogradation value of the modified rice flour is 2000 - 2500 cp, preferably 2200 - 2400 cp; the total soluble protein content of the modified rice flour is 3 - 5%; the amylose content of the modified rice flour is 12 - 18 wt%; the gel strength of the modified rice flour is 7000 - 8500 g, preferably 7500 - 8000 g.

5. A preparation method of modified rice flour, characterized in that, It includes obtaining the modified rice flour by optionally hulling and whitening the modified rice raw material according to any one of claims 1 - 4 and finally grinding it. Preferably, it is not soaked before grinding.

6. A modified rice flour, characterized in that, The modified rice flour has a final viscosity of 4600 - 5300 cp, preferably 4700 - 5300 cp, more preferably 4800 - 5200 cp; the retrogradation value of the modified rice flour is 2000 - 2500 cp, preferably 2200 - 2400 cp; the total soluble protein content of the modified rice flour is 3 - 5%; the amylose content of the modified rice flour is 12 - 18 wt%; the gel strength of the modified rice flour is 7000 - 8500 g, preferably 7500 - 8000 g.

7. A straight rice noodle raw material, characterized in that, Comprising the modified rice flour according to claim 5 or 6. Preferably, it further comprises aged high amylose indica rice flour with an amylose content of 20% to 26%, preferably 24% to 26%. Preferably, based on the total mass of the rice flour raw material, the content of the modified rice flour is 90% or less, preferably 5% to 70%, more preferably 10% to 60%, still more preferably 20% to 50%, and most preferably 30% to 40%.

8. The straight rice noodle raw material according to claim 7, characterized in that, The amylose content of the raw material of the straight rice noodles is 17% to 24%, preferably 18% to 22%, and most preferably 18% to 21%.

9. A straight rice noodle, characterized in that, Prepared by using the modified rice raw material according to any one of claims 1 to 4, or the modified rice flour according to claim 5 or 6, or the raw material of the straight rice noodles according to claim 7 or 8.

10. Use of the modified rice flour according to claim 6 in the preparation of the raw material of the straight rice noodles or the straight rice noodles; preferably, in the said use, based on the total weight of the raw material of the straight rice noodles, the content of the modified rice flour is 90% or less, preferably 5% to 70%, more preferably 10% to 60%, still more preferably 20% to 50%, and most preferably 30% to 40%.

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