Konjac rice noodles and preparation method thereof

Abstract

The invention discloses konjak rice noodles and a preparation method thereof. The method comprises the following steps: sequentially pulping rice milk and a mixture of konjak flour and water, performing steam curing, and performing extrusion forming to obtain the konjak rice noodles, wherein the weight ratio of the rice milk to the konjaku flour to the water is 8: 1: 1; the steam curing time is 3-5 minutes. The konjaku flour rich in resistant starch, dietary fibers and various nutritional ingredients is added into the rice milk, and the toughness of the rice noodles is improved by utilizing a steam curing technology, so that the prepared konjaku rice noodles are not easy to break, smooth in mouth feel and suitable for people with hyperglycemia, diabetes and the like to eat.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, and in particular to konjac rice noodles and a preparation method thereof. Background Art

[0002] Rice noodles, also known as rice vermicelli, are a traditional Chinese pasta. They are not only smooth and chewy, but also rich in nutritional value, rich in carbohydrates, protein, cellulose and multiple vitamins. However, rice noodles themselves have a high carbohydrate content. After carbohydrates are digested and absorbed, they are converted into glucose, which can cause blood sugar to rise rapidly, and is an important cause of obesity, hyperglycemia, diabetes and other diseases.

[0003] Most of the rice noodles currently produced are brittle and prone to breaking. In addition, rice noodles can easily increase blood sugar levels. Long-term high glycemic index diets may also lead to abnormal blood sugar metabolism and increase the risk of diabetes.

[0004] Therefore, it is necessary to provide a rice noodle with good toughness and rich in resistant starch that can meet the needs of healthy diet. Summary of the invention

[0005] The invention aims to provide a preparation method of konjac rice noodles. Only konjac flour is added to the rice noodles, and the konjac rice noodles are quickly matured by using a steam ripening technology. The matured rice noodles are more tough, not easy to break, and have a smooth mouthfeel. Meanwhile, since the konjac flour is rich in resistant starch, the prepared konjac rice noodles have a lower digestion and absorption rate, can slow down the rising speed of blood sugar, and are helpful to control the blood sugar level.

[0006] To solve the above problems, the first aspect of the present invention provides a method for preparing konjac rice noodles, comprising: beating a mixture of rice slurry and konjac flour and water in sequence, steam-ripening, and extruding to obtain konjac rice noodles; wherein the weight ratio of the rice slurry, konjac flour and water is 8:1:1; and the steam-ripening time is 3-5 minutes.

[0007] Preferably, the method for preparing rice slurry comprises: washing soaked rice, mixing the washed rice with water to form slurry; adding 1.5% brewer's yeast to the slurry, sealing and fermenting at 25° C.; cooling after fermentation to obtain the rice slurry.

[0008] Preferably, the soaking time is 5-8 hours.

[0009] Preferably, the fermentation time is 6 hours.

[0010] Preferably, the preparation method of konjac flour comprises:

[0011] Dehydrating and drying the washed konjac to obtain dried konjac flakes;

[0012] The dried konjac flakes are crushed and sieved to obtain konjac flour.

[0013] Preferably, the dried konjac slices are struck by a high-speed rotating blade or a hammer.

[0014] Preferably, the dried konjac flakes are crushed by a fine flour mill.

[0015] Preferably, the diameter of the konjac rice noodles obtained after extrusion molding is 2.5 mm.

[0016] Preferably, the method further comprises the step of placing the konjac rice noodles in a cool, dry and ventilated place for aging for 24 hours.

[0017] According to another aspect of the present invention, a konjac rice noodle is provided, which is obtained by processing using the above method.

[0018] The above technical solution of the present invention has the following beneficial technical effects:

[0019] The invention slows down the rising speed of blood sugar by adding konjac flour rich in resistant starch, dietary fiber and multiple nutrients into rice slurry; at the same time, the toughness of rice noodles is improved by steam ripening technology, so that the prepared konjac rice noodles are not easy to break, have a smooth taste and are suitable for people with high blood sugar, diabetes and the like. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0021] As a natural plant food, konjac's main ingredient is glucomannan, a high molecular compound with strong water absorption. When konjac flour absorbs water, its volume can expand 80-100 times to form a gelatinous substance. This substance is slowly digested in the stomach and can give people a sense of fullness, thereby reducing the intake of other high-calorie foods;

[0022] At the same time, konjac is rich in resistant starch, which is digested slowly and has a low digestion and absorption rate. By consuming foods high in resistant starch, the rate at which blood sugar rises can be reduced. The more resistant starch a food contains, the smaller the rise in blood sugar will be.

[0023] Therefore, the present invention uses rice as a main raw material, and sequentially performs beating, steam ripening, extrusion molding and other processes on a mixture of rice slurry, konjac flour and water to obtain konjac rice noodles;

[0024] The weight ratio of rice slurry, konjac flour and water is 8:1:1;

[0025] The steam aging time is 3-5 minutes.

[0026] The present invention prepares a konjac rice noodle suitable for people who need to control blood sugar, such as diabetes, by adding only a natural food additive, and the konjac rice noodle has a certain toughness and is not prone to the problem of breaking. Compared with rice noodles added with multiple raw materials on the market, the konjac rice noodle of the present invention has a single ingredient, a simple preparation method, a low processing cost, higher toughness and a low glycemic index, and is conducive to consumption by people with obesity, constipation, hyperlipidemia and those who want to prevent stomach and intestinal cancer.

[0027] In a preferred embodiment of the present invention, the following preparation steps are included:

[0028] Step S1-1. preparing rice milk;

[0029] Specifically, the process includes: putting rice into a container, adding clean water a few centimeters above the surface of the rice, soaking for 5-8 hours, pouring out the dirty water, and repeatedly rinsing with clean water to obtain clean rice; mixing rice and water in a weight ratio of 1:1 and putting them into a beater to obtain rice slurry.

[0030] In this step, the rice is soaked to make the rice grains absorb water, swell and soften, which helps the rice grains to be easier to mix and cook with other materials during the subsequent beating and cooking process.

[0031] Step S1-2. Fermentation;

[0032] 1.5% by weight of brewer's yeast is added to the rice slurry prepared in step S1-1, the rice slurry is placed in a fermentation container and then the container is sealed, fermented at 25° C. for 6 hours, and cooled to obtain rice slurry.

[0033] In this step, the texture of konjac rice noodles is improved by fermenting with brewer's yeast, making them softer and more elastic and increasing the taste; at the same time, the rice noodles made with the fermented rice slurry are easier to cook and present a richer taste and flavor.

[0034] Step S2. preparing konjac flour;

[0035] Specifically include: selecting fresh, pest-free and non-deteriorated konjac raw materials, washing the surface of the konjac with clean water to remove mud, sand and other impurities;

[0036] Cut the cleaned konjac into small pieces, put them into a dryer for drying, and obtain konjac dried slices;

[0037] Crushing the konjac dried slices, allowing the dried slices to be crushed into powder by the high-speed rotating blades or hammering force in the machine; preferably a fine powder machine;

[0038] The crushed konjac powder is screened by a sieving machine, and finer konjac powder is preferably used as the processing raw material of konjac rice noodles.

[0039] Step S3. Mixing and beating;

[0040] The rice slurry obtained in step S1 and the konjac flour in step S2 are mixed and put into a beater to make konjac rice slurry, or the rice slurry obtained in step S1 and the konjac flour finished product are mixed and put into a beater to make konjac rice slurry;

[0041] Pour the beaten konjac rice milk into the filter for filtering. During the filtering process, the filter can be cleaned several times to ensure that the impurities in the konjac rice milk are completely removed.

[0042] Preferably, the weight ratio of rice slurry, konjac flour and water is 8:1:1.

[0043] Step S4. Steam aging;

[0044] Fill the water tank of the rice noodle machine with water and heat it. When it boils and steam is generated, add konjac rice slurry from the hopper and use steam to mature the slurry in the rice noodle machine to obtain cooked rice slurry. The steam maturation time is 3-5 minutes.

[0045] Step S5. extrusion molding;

[0046] The cooked rice slurry is extruded into elongated strips through a die of an extruder, and cut into strips according to a certain length to obtain konjac rice noodles;

[0047] Preferably, the diameter of the konjac rice noodles during extrusion molding is 2.5 mm.

[0048] The cooked konjac rice noodles can be packaged and stored after aging, or can be eaten directly after being boiled without aging.

[0049] Therefore, the method further includes: step S6. placing the konjac rice noodles in a cool, dry and ventilated place and aging them for 24 hours before packaging.

[0050] The present invention aims to protect a preparation method of konjac rice noodles, wherein part of the starch in the rice slurry is fermented, cooled, and reheated to form resistant starch, which increases the viscosity and toughness of the rice noodles, making them more chewy and more delicious. Meanwhile, only konjac flour, a natural food additive, is added, which not only increases dietary fiber and multiple nutrients, but also makes full use of the resistant starch rich in konjac flour, reduces the digestion and absorption rate of konjac rice noodles by the intestine, thereby slowing down the rising speed of blood sugar, and helping to control blood sugar levels; and in combination with the processing technology, reduces the breaking rate of konjac rice noodles.

[0051] Konjac rice noodles of the present invention are carried out to the following test and comparative experiment:

[0052] 1. Determination of in vitro digestibility of rice noodles

[0053] 200 mg of konjac rice noodle freeze-dried powder was dispersed in amyloglucosidase (50 U / mL) and 20 mL of porcine pancreatic α-amylase (290 U / mL), and the pH was adjusted to 5.2 with HCL-KCL buffer solution, and then the mixture was placed in an oscillating water bath at 37°C. 0.2 mL of the oscillated mixture was extracted at 0, 10, 20, 30, 60, 90, 120, and 180 minutes, and 4 ml of anhydrous ethanol was added to inactivate the enzyme. After centrifugation (4000 r / min) for 20 min, the supernatant was collected, and the precipitate was washed twice with 3 ml of distilled water, and the supernatant was combined. 2 ml of the supernatant was taken and mixed with 1.5 ml of 3,5-dinitrosalicylic acid, respectively, and boiled in a water bath for 7 min, and then taken out and cooled to room temperature. The volume was made up to 25 ml with distilled water. The absorbance was measured at 520 nm with 3,5-dinitrosalicylic acid solution as blank, and the glucose content was calculated according to the regression equation of the glucose standard curve. The percentage of hydrolyzed starch is the glucose content multiplied by 0.9. Rapidly digestible starch (RDS) is digested within 20 minutes, slowly digestible starch (SDS) is digested between 20 minutes and 120 minutes, and resistant starch (RS) is digested after 120 minutes.

[0054] 2. Test of rice noodle breakage rate

[0055] Take 3 portions of konjac rice noodles with a length of more than 10 cm, each weighing 150 g, soak them in boiling water for 5 minutes, filter out the water, then filter them in cold water for 1 minute, pour them into a container, weigh the rice noodles below 5 cm and above 5 cm respectively, and calculate the breakage rate.

[0056]

[0057] Where M1 is the mass of the rice strips less than 5 cm in length (g);

[0058] M2 is the mass (g) of the rice noodle with a length exceeding 10 cm.

[0059] Embodiment 1:

[0060] Wash the rice after soaking for 5 hours, mix it with water in a weight ratio of 1:1 to form a slurry;

[0061] Add 1.5% of brewer's yeast to the slurry, seal it and ferment it at 25° C. for 6 hours to form rice slurry;

[0062] The rice slurry is steam-ripened in a rice noodle machine for 5 minutes, and then extruded into konjac rice noodles with a diameter of 2.5 mm through a die of an extruder. The noodles are left to age after being formed, and the aged rice noodles can be eaten within 24 hours.

[0063] Embodiment 2:

[0064] Wash the rice after soaking for 5 hours, mix it with water in a weight ratio of 1:1 to form a slurry;

[0065] Add 1.5% of brewer's yeast to the slurry, seal it and ferment it at 25° C. for 6 hours to form rice slurry;

[0066] The rice slurry is steam-ripened in a rice noodle machine for 10 minutes, and then extruded into konjac rice noodles with a diameter of 2.5 mm through a die of an extruder. The formed konjac rice noodles are left to age, and the aged konjac rice noodles can be eaten within 24 hours.

[0067] Embodiment 3:

[0068] Wash the rice after soaking for 5 hours, mix it with water in a weight ratio of 1:1 to form a slurry;

[0069] Add 1.5% of brewer's yeast to the slurry, seal it and ferment it at 25° C. for 6 hours to form rice slurry;

[0070] The rice slurry, the prepared konjac flour and water are beaten in a weight ratio of 8:1:1 to obtain konjac rice slurry;

[0071] The konjac rice slurry is steam-ripened in a rice noodle machine for 5 minutes and then extruded into konjac rice noodles with a diameter of 2.5 mm through a die of an extruder. The formed noodles are left to stand for aging, and the aged rice noodles can be eaten within 24 hours.

[0072] Embodiment 4:

[0073] Wash the rice after soaking for 5 hours, mix it with water in a weight ratio of 1:1 to form a slurry;

[0074] Add 1.5% of brewer's yeast to the slurry, seal it and ferment it at 25° C. for 6 hours to form rice slurry;

[0075] The rice slurry, the prepared konjac flour and water are beaten in a weight ratio of 8:1:1 to obtain konjac rice slurry;

[0076] The konjac rice slurry is steam-ripened in a rice noodle machine for 10 minutes and then extruded into konjac rice noodles with a diameter of 2.5 mm through a die of an extruder. The formed noodles are left to stand for aging, and the aged rice noodles can be eaten within 24 hours.

[0077] Table 1 Starch content of konjac rice noodles in each embodiment

[0078]

[0079] Compared with Example 1, Example 2 in Table 1 has an increased content of rapidly digestible starch (RDS), a decreased content of slowly digestible starch (SDS), and a decreased content of resistant starch (RS);

[0080] Compared with Example 3, the RDS content of Example 4 increased, the SDS content did not change significantly, and the RS content decreased slightly;

[0081] It can be seen that steam cooking time affects the starch digestion rate. The longer the time, the higher the content of fast-digestible starch.

[0082] Comparing the data of Example 3 with that of Example 1, in terms of the content of resistant starch (RS), the RS content of the konjac flour increased by 16.20%, indicating that the addition of konjac flour can significantly increase the RS content;

[0083] In Example 3, the RDS content is lower, and the SDS and RS contents are higher, indicating that the optimal raw material ratio and the optimal steam ripening time of the present invention make the rice noodle starch digestion slower and more suitable for people with diabetes, high blood sugar, etc.

[0084] Table 2 Breakage rate of fresh wet rice noodles in each embodiment

[0085]

[0086] As shown in Table 2, after adding konjac flour, the breaking rate of Example 3 and Example 4 was significantly reduced compared with Example 1 and Example 2 without konjac flour.

[0087] Combined with the data in Table 1, it can be seen that after adding konjac flour, the RS content is significantly increased, and a higher content of RS can provide better toughness for rice noodles.

[0088] Table 3 Glycemic index of fresh wet rice noodles in each embodiment

[0089]

[0090] As shown in Table 3, compared with Example 3, the glycemic index of rice noodles in Example 2 is reduced from 85 to 65, a decrease of 23.53%.

[0091] In summary, the konjac rice noodles processed by the konjac rice noodle preparation method provided by the present invention have good elasticity, are tough, are not easy to break, and are resistant to boiling; the glycemic index after consumption is low, and the noodles are suitable for consumption by people with high blood sugar, diabetes, etc.; the preparation method is relatively easy, the process flow is easy to control, the consumption of food additives is reduced, and large-scale production can be well achieved to meet market demand.

[0092] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A method for preparing konjac rice noodles, characterized in that, include: The mixture of rice slurry, konjac flour and water is sequentially beaten, steam-ripened and extruded to obtain konjac rice noodles; The weight ratio of rice slurry, konjac flour and water is 8:1:1; The steam aging time is 3-5 minutes.

2. The method according to claim 1, characterized in that The preparation method of the rice slurry comprises: Wash the soaked rice and mix with water in a weight ratio of 1:1 to form a slurry; Adding 1.5% of brewer's yeast to the slurry, sealing and fermenting at 25° C.; After fermentation is completed, the mixture is cooled to obtain the rice slurry.

3. The method according to claim 2, characterized in that The soaking time is 5-8 hours.

4. The method according to claim 2, characterized in that: The fermentation time is 6 hours.

5. The method according to claim 1, characterized in that The preparation method of described konjac flour comprises: Dehydrating and drying the washed konjac to obtain dried konjac flakes; The dried konjac flakes are crushed and sieved to obtain konjac flour.

6. The method according to claim 5, characterized in that The dried konjac slices are hit by a high-speed rotating blade or a hammer.

7. The method according to claim 6, characterized in that The dried konjac flakes are crushed by a fine powder machine.

8. The method according to claim 1, characterized in that: The diameter of the konjac rice noodles obtained after the extrusion molding is 2.5 mm.

9. The method according to claim 8, characterized in that The method also includes the step of placing the konjac rice noodles in a cool, dry and ventilated place and allowing them to stand and age for 24 hours.

10. A konjac rice noodle, characterized in that: Processing using the method according to any one of claims 1 to 9.

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