Composite dietary fiber low-glycemic rice noodles and preparation method thereof

Abstract

The invention relates to composite dietary fiber low-glycemic rice noodles and a preparation method thereof, and belongs to the technical field of rice noodle processing. The preparation raw materials of the rice noodles comprise the following components in parts by weight: 45-85 parts of rice flour, 5-12 parts of coarse rice flour, 5-22 parts of sugar-stabilizing rice flour, 5-14 parts of mung bean starch, 5-8 parts of vital gluten, 2-5 parts of konjaku flour, 1-5 parts of oat flour, 1-3 parts of soybean flour and 18-22 parts of water. The composite dietary fiber low-glycemic-content rice noodles provided by the invention have the advantages of composite dietary fibers and low glycemic content, are high in nutritional value, can delay starch digestion, and provide more edible choices for sugar-controlled people and diabetic people.

Description

Technical Field

[0001] The invention relates to the technical field of rice noodle processing, and in particular to composite dietary fiber low-glycemic rice noodles and a preparation method thereof. Background Art

[0002] In recent years, metabolic diseases such as diabetes and obesity have become a global public health issue. Data show that the incidence of diabetes continues to rise, and is showing a clear trend of younger age, with the proportion of children and adolescents increasing. At the same time, obesity, as an important cause of chronic diseases such as diabetes and cardiovascular disease, is becoming more prevalent worldwide. This situation has prompted the public to pay more attention to the glycemic properties and nutritional composition of food, especially in the context of dietary structure transformation, the need to improve traditional staple foods is becoming increasingly urgent.

[0003] Traditional rice noodles are made from refined rice flour as the main raw material. The processing process leads to a large loss of natural dietary fiber, with a loss rate of up to 70%-80%. Refined starch is easier to digest and absorb quickly due to changes in molecular structure, significantly increasing postprandial blood sugar response, with GI values ​​generally exceeding 80, which is not conducive to blood sugar control. Studies have shown that long-term intake of high-glycemic staple foods will increase the risk of insulin resistance and become a potential cause of metabolic syndrome.

[0004] Dietary fiber slows down the digestion rate of carbohydrates through the physical barrier effect, while promoting the production of short-chain fatty acids to improve the balance of sugar and lipid metabolism. Clinical data show that daily intake of dietary fiber can significantly reduce the risk of diabetes. In addition, dietary fiber has a synergistic effect on obesity prevention and control through mechanisms such as regulating intestinal flora and enhancing satiety. Therefore, the scientific combination of dietary fiber and staple food ingredients has become an important technical path to improve metabolic health.

[0005] The present invention focuses on this key demand and is committed to developing a composite dietary fiber low-glycemic rice noodle. Through precise raw material screening and ratio optimization, and prepared by an appropriate preparation method, it has both taste and nutritional value. It is hoped that a delicious, healthy, nutritious and low-glycemic staple food option can be provided to consumers, providing more food options for diabetics and people who control sugar. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a composite dietary fiber low-glycemic rice noodle and a preparation method thereof. The rice noodle provided by the present invention has both a low glycemic index and good texture characteristics, providing more eating options for diabetics and people who control their sugar.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a composite dietary fiber low-glycemic rice noodle, the preparation raw materials comprising the following components in parts by weight: 45-85 parts of rice flour, 5-12 parts of brown rice flour, 5-22 parts of stable sugar rice flour, 5-14 parts of mung bean starch, 5-8 parts of gluten powder, 2-5 parts of konjac flour, 1-5 parts of oat flour, 1-3 parts of soybean flour, and 18-22 parts of water.

[0009] Preferably, the stable sugar rice is rice rich in resistant starch. The stable sugar rice has a relatively high content of RS2 resistant starch, which is not easily digested and absorbed in the human intestine, has the advantages of delaying starch digestion and being easy to shape, and is suitable as a raw material for the production of low-glycemic rice noodles.

[0010] The present invention selects the raw materials prepared by the above-mentioned specific weight portions of components to provide consumers with a healthy, nutritious and low-glycemic staple food choice. Among them, compared with ordinary rice, stable sugar rice contains more endogenous resistant starch content. Due to the complex entanglement of its starch molecules, it is difficult to be quickly decomposed by amylase, and the eGI value of rice noodles can be regulated to reduce. Brown rice is a rice with full nutritional retention. Compared with refined rice, it is rich in more dietary fiber and vitamins. Adding a certain proportion of brown rice can increase the nutritional value of rice noodles, and can delay starch digestion, providing more edible options for sugar control people and diabetic people. Konjac and oats contain more dietary fiber, which can play a physical shielding role in the small intestine, hinder the decomposition of starch by amylase, delay the digestion of starch, and comprehensively reduce postprandial blood sugar fluctuations.

[0011] In addition, mung bean starch can adjust the texture and shear properties of rice noodles; gluten contains more than 80% gluten protein, which can improve the toughness of rice noodles. The present invention adds brown rice, sugar-stabilized rice, mung bean starch, gluten, konjac flour, oats, and soybean flour in specific weight portions to rice flour, and can also simultaneously adjust and improve the hardness, chewiness, cooking quality, and color of rice noodle products, so that the rice noodles have unique edible properties and good appearance while reducing postprandial blood sugar fluctuations.

[0012] Compared with the prior art, the composite dietary fiber low-glycemic rice noodles provided by the present invention have a composite of multiple dietary fibers, high nutritional value, and a low glycemic index, with an eGI value below 55; and it can take into account good chewiness, steaming quality and color, providing more delicious, nutritious and healthy food options for ordinary consumers, diabetics and people who control sugar.

[0013] Preferably, the raw materials for preparing the composite dietary fiber low-glycemic rice noodles further include the following components in parts by weight: 1-2 parts of chickpea flour, 0.8-2 parts of inulin, 0.2-1 parts of galacto-oligosaccharide, and 0.4-1 parts of white kidney bean extract.

[0014] Among them, inulin, as a pure natural water-soluble dietary fiber, can absorb a large amount of water in the intestines to form a viscous gel-like substance. This gel structure will form a physical barrier around the starch granules, hindering the contact between digestive enzymes and starch, making it difficult for amylase and other enzymes to approach starch molecules, thereby reducing the digestion rate and digestibility of starch. Chickpea flour is rich in dietary fiber and protein, which can help improve digestive function. Galacto-oligosaccharide is a prebiotic that can promote the proliferation of beneficial intestinal bacteria. White kidney bean extract can reduce carbohydrate hydrolysis by inhibiting the activity of α-amylase, thereby assisting in controlling postprandial blood sugar.

[0015] Preferably, the raw materials for preparing the composite dietary fiber low-glycemic rice noodles include the following components in parts by weight: 45-50 parts of rice flour, 10-12 parts of brown rice flour, 10-22 parts of stable sugar rice flour, 8-14 parts of mung bean starch, 5-8 parts of gluten, 2-4 parts of konjac flour, 1-4 parts of oat flour, 1-2 parts of soybean flour, 1-2 parts of chickpea flour, 0.8-1.5 parts of inulin, 0.2-1 parts of galacto-oligosaccharide, 0.4-1 parts of white kidney bean extract, and 20 parts of water.

[0016] The composite dietary fiber low-glycemic rice noodles prepared by using the raw materials prepared by weight of the components have an eGI value below 52, ​​a cooking breakage rate below 2.5%, a more stable structure, a high shear force, and are slightly yellow.

[0017] In a second aspect, the present invention provides a method for preparing the composite dietary fiber low-glycemic rice noodles, comprising the following steps:

[0018] (1) screening and mixing the prepared raw materials, and extruding the noodles by a single screw extruder to obtain preliminarily formed rice noodles;

[0019] (2) allowing the preliminarily formed rice noodles to stand for aging, and then introducing hot steam to perform a aging process to obtain aging rice noodles;

[0020] (3) The cooked rice noodles are sprayed, then dried with gradient hot air, and cut to obtain the composite dietary fiber low-glycemic rice noodles.

[0021] As a preferred technical solution of the present invention, the inulin and galacto-oligosaccharide in the preparation raw materials are first dissolved in water and then mixed with the materials.

[0022] Preferably, the screening is performed using an 80-mesh sieve.

[0023] Preferably, in the single-screw extruder, the aperture of the single-screw mold is 1.6 mm.

[0024] Preferably, the temperature set for the single screw extruder is 155-160°C.

[0025] Preferably, the temperature of the static aging is room temperature, and the time is 8-12 hours.

[0026] Preferably, the aging treatment conditions are: steam aging at a relative humidity of 99% and a temperature of 60-70° C. for 6 hours.

[0027] Preferably, the conditions for gradient hot air drying are: zone I temperature is 55-60°C, relative humidity is 90-95%, and time is 60-100 min; zone II temperature is 50-55°C, relative humidity is 70-75%, and time is 100-140 min; zone III temperature is 40-45°C, relative humidity is 65-70%, and time is 100-140 min; zone IV temperature is 30-32°C, relative humidity is 65-70%, and time is 30-60 min.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention provides a composite dietary fiber low-glycemic rice noodle by combining rice flour with specific weight portions of brown rice flour, stable sugar rice flour and other preparation materials, thereby achieving the goal of compounding multiple dietary fibers in the rice noodles, improving the nutritional value of traditional rice noodles, and having a low glycemic index, thereby providing a new staple food option for diabetics and people who control their sugar levels. At the same time, the rice noodles of the present invention have good chewiness, cooking quality and color, thereby providing consumers with a staple food that is both delicious and nutritious and healthy, and have high market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the preparation process of the composite dietary fiber low-glycemic rice noodles of the present invention;

[0031] Figure 2 The shear properties of rice noodles prepared from different raw materials in the examples and comparative examples are shown in FIG.

[0032] Figure 3 This is a diagram showing the digestibility characteristics of rice noodles made from different raw materials in the examples and comparative examples. DETAILED DESCRIPTION

[0033] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below in conjunction with specific examples. The test methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0034] Example 1

[0035] An embodiment of the composite dietary fiber low-glycemic rice noodles of the present invention, the raw materials for preparing the composite dietary fiber low-glycemic rice noodles of this embodiment are composed of the following components in parts by weight: 55.3 parts of rice flour, 12 parts of brown rice flour, 10 parts of sugar-stabilized rice, 10 parts of mung bean starch, 8 parts of gluten, 4 parts of oat flour, 4 parts of konjac flour, 2 parts of soybean flour, and 20 parts of water;

[0036] The method for preparing the composite dietary fiber low-glycemic rice noodles described in this embodiment comprises the following steps:

[0037] (1) washing the rice and drying it thoroughly, grinding it into powder to obtain rice flour, sieving all powder materials including rice flour, brown rice flour, sugar-stabilized rice, mung bean starch, gluten, oat flour, konjac flour, and soybean flour through an 80-mesh sieve to ensure the standard of the raw materials, and then accurately weighing the ingredients according to a preset weight ratio;

[0038] The powders are mixed and poured into a mixer, water is slowly added, and stirring is continued to make the powders and water uniformly mixed to obtain a mixture, which is then transferred to a single screw extruder to extrude wire at a high temperature of 160° C. to obtain preliminarily formed rice noodles;

[0039] (2) Immediately transfer the initially formed rice noodles to an aging chamber and allow the rice noodles to age at 25°C for 12 h;

[0040] After the aging of the rice noodles is completed, hot steam is introduced into the rice noodles, and the rice noodles are further aged at 65° C. for 6 hours with a relative humidity of 99% to obtain aged rice noodles;

[0041] (3) quickly placing the cooked rice noodles into a cold water spraying device to loosen the rice noodles and avoid adhesion, thereby ensuring that the rice noodles are in good shape;

[0042] The loosened rice noodles are sent to a drying room, and the gradient hot air drying technology is used to gradually remove the moisture in the rice noodles to achieve a suitable degree of dryness; the dried rice noodles are cut and bagged to obtain the composite dietary fiber low-glycemic rice noodles;

[0043] The conditions for gradient hot air drying are: the temperature of zone I is 60°C, the relative humidity is 90-95%, and the time is 60 minutes; the temperature of zone II is 55°C, the relative humidity is 70-75%, and the time is 120 minutes; the temperature of zone III is 45°C, the relative humidity is 70%, and the time is 120 minutes; the temperature of zone IV is room temperature 32°C, the relative humidity is 65-70%, and the time is 60 minutes. The total time is 6 hours.

[0044] The schematic diagram of the preparation process of the composite dietary fiber low-glycemic rice noodles is as follows: Figure 1 .

[0045] Example 2

[0046] An embodiment of the composite dietary fiber low-glycemic rice noodles of the present invention, the raw materials for preparing the composite dietary fiber low-glycemic rice noodles of this embodiment are composed of the following components in parts by weight: 50 parts of rice flour, 10 parts of brown rice flour, 22 parts of stable sugar rice, 8 parts of mung bean starch, 5 parts of gluten, 1 part of oat flour, 2 parts of konjac flour, 1 part of chickpea flour, 1 part of soybean flour, 0.2 parts of galacto-oligosaccharide, 0.8 parts of inulin, 0.4 parts of white kidney bean extract, and 20 parts of water;

[0047] The preparation method of the composite dietary fiber low-glycemic rice noodles described in this embodiment refers to the preparation method in Example 1.

[0048] Example 3

[0049] An embodiment of the composite dietary fiber low-glycemic rice noodles of the present invention, the raw materials for preparing the composite dietary fiber low-glycemic rice noodles of this embodiment are composed of the following components in parts by weight: 48 parts of rice flour, 12 parts of brown rice flour, 10 parts of stable sugar rice, 10 parts of mung bean starch, 8 parts of gluten, 4 parts of oat flour, 4 parts of konjac flour, 2 parts of chickpea flour, 2 parts of soybean flour, 0.5 parts of galacto-oligosaccharide, 2 parts of inulin, 0.8 parts of white kidney bean extract, and 20 parts of water;

[0050] The preparation method of the composite dietary fiber low-glycemic rice noodles described in this embodiment refers to the preparation method in Example 1.

[0051] Example 4

[0052] An embodiment of the composite dietary fiber low-glycemic rice noodles of the present invention, the raw materials for preparing the composite dietary fiber low-glycemic rice noodles of this embodiment are composed of the following components in parts by weight: 45 parts of rice flour, 12 parts of brown rice flour, 16 parts of stable sugar rice, 14 parts of mung bean starch, 6 parts of gluten, 2 parts of oat flour, 2 parts of konjac flour, 2 parts of chickpea flour, 1 part of soybean flour, 1 part of galacto-oligosaccharide, 1.5 parts of inulin, 1 part of white kidney bean extract, and 20 parts of water;

[0053] The preparation method of the composite dietary fiber low-glycemic rice noodles described in this embodiment refers to the preparation method in Example 1.

[0054] Comparative Example 1

[0055] The raw materials for preparing the rice flour of Comparative Example 1 are composed of the following components in parts by weight: 88.3 parts of rice flour, 5 parts of brown rice, 5 parts of mung bean starch, 5 parts of gluten powder, and 20 parts of water;

[0056] The preparation method of rice noodles in Comparative Example 1 refers to the preparation method of Example 1.

[0057] Comparative Example 2

[0058] The raw materials for preparing the rice flour of Comparative Example 2 are composed of the following components in parts by weight: 55.3 parts of rice flour, 12 parts of brown rice flour, 10 parts of sugar-stabilized rice, 10 parts of mung bean starch, 8 parts of gluten, 4 parts of konjac flour, 4 parts of oatmeal flour, and 20 parts of water;

[0059] The preparation method of rice noodles in Comparative Example 2 refers to the preparation method of Example 1.

[0060] The raw material components for preparing rice noodles in Examples 1-4 and Comparative Examples 1-2 are shown in Table 1 below.

[0061] Table 1: Composition of raw materials for preparing rice noodles in the examples and comparative examples

[0062] Components / parts by weight Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Rice flour 53.3 50 48 45 88.3 55.3 Brown Rice Flour 12 10 12 12 5 12 Sugar-stable rice 10 22 10 16 0 10 Mung Bean Starch 10 8 10 14 5 10 Gluten 8 5 8 6 5 8 Oatmeal flour 4 1 4 2 0 4 Konjac flour 4 2 4 2 0 4 Chickpea flour 0 1 2 2 0 0 Soybean flour 2 1 2 1 0 0 Galacto-oligosaccharides 0 0.2 0.5 1 0 0 Inulin 0 0.8 2 1.5 0 0 White Kidney Bean Extract 0 0.4 0.8 1 0 0 water 20 20 20 20 20 20

[0063] Effect Example 1

[0064] In order to explore the texture characteristics of the composite dietary fiber low-glycemic rice noodles provided by the present invention, the following TPA test was performed on the rice noodles of the embodiment and the comparative example:

[0065] The rice noodles cooked at the optimal cooking time were immediately placed on the sample plate of the texture analyzer for testing. The P36 / R probe was selected, the pre-test speed was 2mm / s, the test speed was 1mm / s, the post-test speed was 2mm / s, the compression ratio was 60%, the trigger force was 0.04905N, the interval between two compressions was 5s, and each sample was tested 3 times. The texture properties of rice noodles prepared from different raw materials in the embodiments and comparative examples are shown in Table 2. There are significant differences between the values ​​indicated by different letters in the same column (p < 0.05).

[0066] Table 2 Results of texture characteristics of different rice noodles in the examples and comparative examples

[0067]

[0068]

[0069] From Table 2, we can see that:

[0070] The rice noodles in Comparative Example 1 have the lowest hardness, which is only 513.10g, which may be due to the relatively small amount of amylose contained in it, and a good gel network structure cannot be formed after regeneration. The elasticity of all samples did not change significantly. The reduction in viscosity of Examples 3 and 4 may be due to the addition of konjac flour and oat flour. Example 4 shows the greatest chewiness. In general, the addition of ingredients such as stable sugar rice, brown rice, mung bean starch, gluten, konjac flour, oats and inulin can significantly change the hardness and chewiness of the rice noodle products of the present invention, while having little effect on elasticity, and the effect on viscosity varies depending on the type and proportion of the additives.

[0071] Effect Example 2

[0072] In order to explore the shear properties of the composite dietary fiber low-glycemic rice noodles provided by the present invention, the following shear tests were performed on the rice noodles of the embodiment and the comparative example:

[0073] The rice noodles with the best cooking time were put into a texture analyzer with an HDP / LKBF probe for testing. The shear property parameters were set to 2 mm / s before the test, 0.10 mm / s after the test, 2 mm / s after the test, 15 g trigger force, and 80% deformation. Three rice noodle samples with uniform thickness were selected for testing each time, and the average value was calculated after three measurements.

[0074] The shear properties of rice noodles prepared from different raw materials in the examples and comparative examples are shown in FIG. Figure 2 Different letters indicate significant differences between values ​​(p < 0.05).

[0075] Depend on Figure 2 It can be seen that the shear force of Example 4 is the largest, reaching 42.03g, and the shear force of Comparative Example 1 is the lowest, only 28.74g. The shear force and hardness of rice noodles show the same trend of change. From the results of Examples 3-5, it can be seen that regulating the proportion of each component in rice noodles can improve the texture characteristics and shear characteristics of rice noodles to a certain extent.

[0076] Effect Example 3

[0077] In order to explore the cooking quality of the composite dietary fiber low-glycemic rice noodles provided by the present invention, the rice noodles of the embodiment and the comparative example were tested as follows:

[0078] ①Sample immersion:

[0079] The rice noodle samples were soaked in 80°C water for 20 min before cooking.

[0080] ②Determination of cooking time:

[0081] Use a beaker to measure about 1000mL of boiling water, place it on an electric stove and heat it to keep the water slightly boiling. Randomly select 20 whole rice noodles, put them into the boiling water, and start timing with a timer. Start sampling from 3 minutes, and then use chopsticks to pick out one noodle every 1 minute and put it into a white porcelain bowl for tasting until it is soft and has no hard core. Record this time as the steaming time.

[0082] ③ Determination of broken strip rate:

[0083] Use a beaker to measure about 1000mL of boiling water, place it on an electric stove and heat it to keep the water slightly boiling. Randomly select 20 intact rice noodles, put them into the boiling water, and start the timer. When the cooking time measured in the previous step is reached, use chopsticks to gently pick out the rice noodles and count the number of broken rice noodles.

[0084] The broken rate is calculated according to the following formula:

[0085]

[0086] in,

[0087] N-number of broken rice noodles;

[0088] ④Determination of cooking loss:

[0089] Take 5 rice noodles in 250 mL of water, cook until the optimal cooking time, then take them out, drain for 3 minutes and weigh them. Dry the remaining soup to constant weight and calculate the cooking loss rate according to the following formula:

[0090]

[0091] The cooking quality test results of rice noodles prepared from different raw materials in the examples and comparative examples are shown in Table 3. Different letters in the same column indicate significant differences (p < 0.05) between the values.

[0092] Table 3 Test results of cooking quality of rice noodles in the examples and comparative examples

[0093] sample Cooking loss (%) Strip breaking rate (%) Rehydration rate (%) Example 1 <![CDATA[7.06±0.22 d ]]> <![CDATA[4.45±0.11 c ]]> <![CDATA[196.78±1.57 b ]]> Example 2 <![CDATA[4.40±0.03 e ]]> <![CDATA[2.29±0.09 d ]]> <![CDATA[204.12±0.87 a ]]> Example 3 <![CDATA[6.63±0.12 d ]]> <![CDATA[0.48±0.31 f ]]> <![CDATA[178.49±1.28 e ]]> Example 4 <![CDATA[8.70±0.32 c ]]> <![CDATA[1.29±0.25 e ]]> <![CDATA[187.54±0.82 c > Comparative Example 1 <![CDATA[10.62±0.43 a ]]> <![CDATA[9.55±0.23 a ]]> <![CDATA[177.83±0.34 e ]]> Comparative Example 2 <![CDATA[9.69±0.24 b ]]> <![CDATA[8.35±0.34 b ]]> <![CDATA[184.55±0.48 d ]]>

[0094] From Table 3 we can see that:

[0095] The cooking loss rates of the composite dietary fiber low-glycemic rice noodles of the embodiments of the present invention are all lower than 9%, among which the cooking loss rate of Embodiment 2 is the smallest, which is only 4.40%; in terms of the breaking rate, Embodiment 3 has the smallest breaking rate, which is only 0.48%, while Comparative Example 1 has the highest breaking rate, which reaches 9.55%; Embodiments 2-4 show a relatively stable rice noodle gel structure during the cooking process.

[0096] Effect Example 4

[0097] In order to explore the color of the composite dietary fiber low-glycemic rice noodles provided by the present invention, the rice noodles of the embodiment and the comparative example were tested as follows:

[0098] Spread the rice noodles flat on the table and measure them with a colorimeter. * Represents brightness, a * represents the red and green values, b * Represents the yellow-blue value, and ΔE represents the color difference from the white board. ΔE is calculated by the following formula:

[0099]

[0100] The color difference results of rice noodles prepared with different raw materials in the examples and comparative examples are shown in Table 4. Different letters in the same column represent significant differences between the values ​​(p < 0.05).

[0101] Table 4 Color difference results of rice noodles in the examples and comparative examples

[0102] sample <![CDATA[L * ]]> a* b* ΔE Example 1 <![CDATA[41.97±0.17 c ]]> <![CDATA[1.09±0.02 ab ]]> <![CDATA[15.36±0.18 c ]]> <![CDATA[52.57±0.24 b ]]> Example 2 <![CDATA[42.23±1.67 c ]]> <![CDATA[0.97±0.38 ac ]]> <![CDATA[15.29±0.98 c ]]> <![CDATA[52.26±1.50 b ]]> Example 3 <![CDATA[41.06±0.86 c ]]> <![CDATA[1.25±0.11 ab ]]> <![CDATA[16.64±0.20 b ]]> <![CDATA[53.75±0.82 b ]]> Example 4 <![CDATA[38.68±0.50 d ]]> <![CDATA[1.03±0.06 abc ]]> <![CDATA[18.32±0.17 a ]]> <![CDATA[56.52±0.72 a ]]> Comparative Example 1 <![CDATA[48.20±0.26 a ]]> <![CDATA[0.75±0.02 c ]]> <![CDATA[10.53±0.10 e ]]> <![CDATA[45.91±0.67 c ]]> Comparative Example 2 <![CDATA[46.33±0.34 b ]]> <![CDATA[0.83±0.04 bc ]]> <![CDATA[11.62±0.07 d ]]> <![CDATA[47.39±0.53 c ]]>

[0103] Wherein, L* represents white brightness, a* represents red-green index, and b* represents yellow-blue index. As shown in Table 4, in the embodiments and comparative examples, as L* decreases from the maximum 48.20 to 38.68, the brightness of the rice noodles gradually decreases, while b* gradually increases. In comparative examples 1 and 2, since only the outer shell of brown rice is removed, the outer bran is retained, and the whole is slightly yellow. In the embodiments of the present invention, due to the addition of components such as soybean flour, the L* of the rice noodles is reduced, the b* is increased, and ΔE is also increased. The rice noodles are yellow as a whole, and have a good color that stimulates people's appetite.

[0104] Effect Example 5

[0105] In order to explore the digestion characteristics and GI value of the composite dietary fiber low-glycemic rice noodles provided by the present invention, the rice noodles of the embodiment and the comparative example were tested as follows:

[0106] 1. Digestion characteristics: refer to the method of Englyst and make slight modifications. Take 0.5g of cooked rice noodles and place them in a 250ml conical flask and add 5 glass beads, add 15mL of 0.5mol / L pH=5.2 acetic acid buffer solution and 10mL of mixed enzyme solution containing saccharifying enzyme (100U / mL) and α-amylase (290U / mL). Place the conical flask in a water bath and shake it at 37℃ with a speed of 170rpm, perform enzymatic reaction and start timing. Accurately draw 1mL of enzymatic solution at 0, 20min, and 120min time periods, place it in a centrifuge tube, add 4mL of anhydrous ethanol to inactivate, centrifuge at 4000rpm for 10min, use the glucose oxidase method, use an enzyme marker to measure the absorbance of the supernatant at 505nm, and calculate the content of fast-digestible starch, slow-digestible starch, and resistant starch according to the following formula.

[0107]

[0108] Among them G 20 :Glucose content in digestive juice at 20min (mg)

[0109] F G :Free glucose content in digestive juice (mg)

[0110] G 120 : Glucose content in digestive juice at 120 minutes (mg)

[0111] TS: Total starch content (mg)

[0112] 2. Estimated GI value:

[0113] ① Sample preparation: soak the rice noodle sample in 80℃ water for 20 minutes, then put it in boiling water to reach the optimal cooking time and remove it for later use;

[0114] ② Oral chewing simulation: refer to the method of Gawlik-Dziki et al. and make appropriate adjustments. Take 1g of the treated rice noodle sample in a conical flask, add 10mL of pH 6.5 phosphate buffer solution containing salivary amylase, tap gently with a mortar for 15s, add 5 glass beads, and shake in a 37℃ water bath for 10min.

[0115] ③ Gastric digestion simulation: adjust the pH to 1.2 with 5M HCL, then add 10mL of 0.03M NaCl solution (pH=1.2) containing pepsin, and shake in a 37°C water bath for 30min.

[0116] ④ Intestinal digestion simulation: Use 1M NaOH to adjust the pH to 7.0, add 10mL of intestinal fluid (add 0.05g of pancreatic enzyme, 0.3g of porcine bile salt, and 0.3g of saccharifying enzyme to 100mL of phosphate buffer solution), 5mL of 120mM NaCl solution and 5mL of 120mM KCl, and shake in a 37℃ water bath for 180min. Accurately aspirate 1mL of sample at 10, 20, 30, 45, 60, 90, 120, 150, and 180min respectively, and put it into a centrifuge tube containing 4mL of anhydrous ethanol, and centrifuge at 5000rpm for 10min.

[0117] ⑤ Glucose determination: Take the supernatant after centrifugation and use a glucose determination kit to measure the absorbance at 505nm to calculate the glucose content in different time periods.

[0118] ⑥Calculation method: Calculate the hydrolysis rate of starch according to the amount of glucose released, draw a curve of the change of starch hydrolysis rate over time, and calculate the digestion curve of all rice noodle samples according to the equation First-order kinetic fitting was performed, model fitting and mapping were performed using origin software, and the hydrolysis equilibrium constant k was calculated.

[0119] The area under the digestion curve (AUC) was calculated by the following formula:

[0120] AUC=C∞(t f -t 0 )-(C∞ / k)[1-e -k(tf-t0) ]

[0121] Where Ct: starch hydrolysis rate at time t; C∞: final starch hydrolysis rate; t f : Total digestion reaction time (180 min); t 0 : digestion start time (0min); k: kinetic constant;

[0122] The hydrolysis index (HI) is calculated by the following formula:

[0123]

[0124] Choose white bread as a reference and calculate the GI of rice noodles using the following formula:

[0125] GI=0.862HI+8.819

[0126] The digestibility characteristics of rice noodles prepared from different raw materials in the examples and comparative examples are shown in FIG. Figure 3 ; The estimated glycemic index results are shown in Table 5 below.

[0127] Table 5 Estimated glycemic index of rice noodles in the examples and comparative examples

[0128] sample eGI Example 1 53 Example 2 51 Example 3 50 Example 4 52 Comparative Example 1 67 Comparative Example 2 61

[0129] Depend on Figure 3 and Table 5:

[0130] RDS is a fast-digesting starch that can be digested and absorbed in the small intestine within 20 minutes; SDS is a slow-digesting starch that can be digested and absorbed in the small intestine within 20-120 minutes; RS is a resistant starch that cannot be digested and absorbed in the small intestine. Compared with Comparative Example 1, with the addition of the raw materials for preparing the composite dietary fiber low-glycemic rice noodles of the present invention, such as stable sugar rice, brown rice, konjac flour, oat flour, etc., and the reasonable ratio of the raw material components prepared, RDS dropped from the initial 52.2% to a minimum of 34.5% (Example 3), a decrease of 29.31%, and the eGI value dropped from 67 to a minimum of 50. Compared with ordinary rice, stable sugar rice contains more endogenous resistant starch content, which reduces the eGI value of rice noodles; brown rice, konjac and oats contain more dietary fiber, which can play a physical shielding role in the small intestine, hinder the decomposition of starch by amylase, delay the digestion of starch, and reduce postprandial blood sugar fluctuations. Inulin blocks the contact between digestive enzymes and starch, making it difficult for amylase and other enzymes to approach starch molecules, and can also reduce the digestion rate and digestibility of starch.

[0131] In summary, the present invention provides a composite dietary fiber low-glycemic rice noodle by combining rice flour with a specific weight portion of rice flour, brown rice flour, stable sugar rice flour, mung bean starch, gluten powder, konjac flour, oat flour, soybean flour and other raw materials, achieving the purpose of compounding multiple dietary fibers in rice noodles and improving the nutritional value of traditional rice noodles. The low glycemic index is evaluated as low as 55, and it takes into account good chewiness and cooking quality, small cooking loss, low breaking rate, deliciousness, nutrition and health, and provides a new staple food choice for consumers of different groups, with high market application prospects.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A composite dietary fiber low-glycemic rice noodle, characterized in that: The raw materials for preparing the composite dietary fiber low-glycemic rice noodles include the following components in parts by weight: 45-85 parts of rice flour, 5-12 parts of brown rice flour, 5-22 parts of sugar-stable rice flour, 5-14 parts of mung bean starch, 5-8 parts of gluten powder, 2-5 parts of konjac flour, 1-5 parts of oat flour, 1-3 parts of soybean flour and 18-22 parts of water.

2. The composite dietary fiber low-glycemic rice noodle according to claim 1, characterized in that: The raw materials for preparing the composite dietary fiber low-glycemic rice noodles also include the following components in parts by weight: 1-2 parts of chickpea flour, 0.8-2 parts of inulin, 0.2-1 parts of galacto-oligosaccharide, and 0.4-1 parts of white kidney bean extract.

3. The composite dietary fiber low-glycemic rice noodle according to claim 2, characterized in that: The raw materials for preparing the composite dietary fiber low-glycemic rice noodles include the following components in parts by weight: 45-50 parts of rice flour, 10-12 parts of brown rice flour, 10-22 parts of sugar-stabilized rice flour, 8-14 parts of mung bean starch, 5-8 parts of gluten powder, 2-4 parts of konjac flour, 1-4 parts of oat flour, 1-2 parts of soybean flour, 1-2 parts of chickpea flour, 0.8-1.5 parts of inulin, 0.2-1 parts of galacto-oligosaccharide, 0.4-1 parts of white kidney bean extract and 20 parts of water.

4. The method for preparing the composite dietary fiber low-glycemic rice noodles according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) screening and mixing the prepared raw materials, and extruding the noodles by a single screw extruder to obtain preliminarily formed rice noodles; (2) allowing the preliminarily formed rice noodles to stand for aging, and then introducing hot steam to perform a aging process to obtain aging rice noodles; (3) The cooked rice noodles are sprayed, then dried with gradient hot air, and cut to obtain the composite dietary fiber low-glycemic rice noodles.

5. The method for preparing composite dietary fiber low-glycemic rice noodles according to claim 4, characterized in that: The sieving is performed using an 80-mesh sieve.

6. The method for preparing the composite dietary fiber low-glycemic rice noodles according to claim 4, characterized in that: In the single-screw extruder, the aperture of the single-screw die is 1.6 mm.

7. The method for preparing composite dietary fiber low-glycemic rice noodles according to claim 4, characterized in that: The temperature set for the single screw extruder was 155-165°C.

8. The method for preparing composite dietary fiber low-glycemic rice noodles according to claim 4, characterized in that: The temperature of the static aging is room temperature, and the time is 8-12 hours.

9. The method for preparing composite dietary fiber low-glycemic rice noodles according to claim 4, characterized in that: The aging treatment conditions are: steam aging for 6 hours at a relative humidity of 99% and a temperature of 60-70°C.

10. The method for preparing composite dietary fiber low-glycemic rice noodles according to claim 4, characterized in that: The conditions for gradient hot air drying are: the temperature of zone I is 55-60°C, the relative humidity is 90-95%, and the time is 60-100 min; the temperature of zone II is 50-55°C, the relative humidity is 70-75%, and the time is 100-140 min; the temperature of zone III is 40-45°C, the relative humidity is 65-70%, and the time is 100-140 min; the temperature of zone IV is 30-32°C, the relative humidity is 65-70%, and the time is 30-60 min.

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