Nutritional rice noodles with high water binding capacity and preparation method thereof

Abstract

The preparation method comprises the following steps: uniformly mixing long-shaped rice flour, corn starch and wheat flour to prepare mixed powder, weighing the mixed powder and a modifier in parts by weight, putting the weighed mixed powder and modifier into a stirring machine, and uniformly mixing for later use; extruding the standby mixture into rice noodles at high temperature by using a twin-screw extruder; sending the extruded and formed rice noodles into a constant-temperature and constant-humidity incubator for standing; the rice noodles are put into cold water to be scattered; feeding the scattered rice noodles into a drying oven for hot air drying; and the dried rice noodles are cut and then bagged, and finished products are formed. The prepared rice noodles have the excellent characteristics of high water binding capacity and rich nutritional value, the hardness and elasticity of the rice noodles are remarkably enhanced, the rice noodles are not prone to adhesion in the production and eating process, meanwhile, the cooking loss rate and the breaking rate of the rice noodles are greatly reduced, and the cooking quality of the rice noodles is improved.

Description

Technical Field

[0001] The invention relates to the technical field of rice noodle processing, in particular to nutritious rice noodles with high water holding capacity and a preparation method thereof. Background Art

[0002] Rice noodles are a traditional food in southern my country, popular among consumers for their smooth, soft texture, ease of consumption, and excellent flavor-adapting properties, making them easy to pair with various soups and sauces. However, rice noodles are primarily composed of amylose, which is susceptible to aging and regeneration. This leads to moisture loss during storage or re-cooking, resulting in a hard and brittle texture. This poses challenges for both consumers and the production process. Summary of the Invention

[0003] In order to solve the technical problems existing in the above-mentioned technology, it is necessary to provide a method for preparing nutritious rice noodles with high water holding capacity, which significantly reduces the loss rate of rice noodles during the rehydration process, enhances the elasticity of rice noodles, and makes the rice noodles have a better taste.

[0004] A method for preparing nutritious rice noodles with high water holding capacity comprises the following steps:

[0005] Step S1: Indica rice flour, corn starch, and wheat flour are mixed evenly to prepare a mixed powder, and the mixed powder and the improver are weighed according to weight, put into a mixer, and mixed evenly for later use;

[0006] Step S2: Extruding the mixture prepared in step S1 into rice noodles using a twin-screw extruder at high temperature;

[0007] Step S3: placing the rice noodles extruded in step S2 into a constant temperature and humidity incubator for static placement;

[0008] Step S4: putting the rice noodles prepared in step S3 into cold water to make them into thin strips;

[0009] Step S5: sending the rice noodles after being shredded in step S4 into an oven for hot air drying;

[0010] Step S6: cutting the rice noodles dried in step S5 and bagging them to form finished products.

[0011] Preferably, in step S1, the improving agent is pea protein.

[0012] Preferably, the addition ratio of the mixed powder to the pea protein is 1:0.1.

[0013] Preferably, in step S1, the improving agent is arabinogalactan.

[0014] Preferably, the ratio of the mixed powder to arabinogalactan is 1:0.002-0.006.

[0015] Preferably, in step S1, the improver is a mixture of pea protein and arabinogalactan.

[0016] Preferably, the mixing ratio of pea protein to arabinogalactan is 0.1:0.002-0.006.

[0017] Preferably, the addition ratio of the mixed powder to the improver is 1:0.1:0.002-0.006.

[0018] Preferably, in step S3, the conditions of the constant temperature and humidity incubator are a temperature of 30° C. and a humidity of 90%, and the incubator is left to stand for 12 hours.

[0019] It is also necessary to provide a nutritious rice noodle with high water holding capacity.

[0020] A high water holding capacity nutritious rice noodle is obtained by using the above-mentioned high water holding capacity nutritious rice noodle preparation method.

[0021] Compared with the prior art, the high water-holding nutritious rice noodles and the preparation method thereof provided by the present invention have the excellent characteristics of high water-holding capacity and rich nutritional value. Pea protein, as a natural plant protein, contains a variety of essential amino acids for the human body. It is nutritious and can also improve the texture characteristics of rice noodles. As a natural polysaccharide, arabinogalactan can be added to rice noodles to enhance the binding ability of starch molecules with water and enhance the internal network structure of the rice noodle gel. After adding pea protein, the hardness and elasticity of the rice noodles are significantly enhanced, and it is not easy to stick together during the production and consumption process. At the same time, the cooking loss rate and breakage rate of the rice noodles are greatly reduced, and the cooking quality of the rice noodles is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 This is a diagram showing the cooking characteristics of different rice noodles of the present invention.

[0024] Figure 2 Graph showing the texture characteristics of different rice noodles according to the present invention.

[0025] Figure 3 4 is the Fourier infrared spectra of different rice noodles of the present invention.

[0026] Figure 4 This is a graph showing the RDS, SDS, and RS contents of different rice noodles of the present invention.

[0027] Figure 5It is a curve diagram of the hydrolysis rate of different rice noodle starches of the present invention.

[0028] Figure 6 2 is a microstructure diagram of different rice noodles of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] Comparative Example 1

[0031] A method for preparing nutritious rice noodles with high water holding capacity comprises the following steps:

[0032] Step S1: Weigh indica rice flour: corn starch: wheat flour in a ratio of 9:0.5:0.5 by weight, put them into a mixer, mix them evenly, and set aside;

[0033] Step S2: Extruding the mixture prepared in step S1 into rice noodles using a twin-screw extruder at high temperature;

[0034] Step S3: placing the rice noodles extruded in step S2 into a constant temperature and humidity incubator for static placement;

[0035] Step S4: putting the rice noodles prepared in step S3 into cold water to loosen them;

[0036] Step S5: sending the rice noodles after being shredded in step S4 into an oven for hot air drying;

[0037] Step S6: cutting the rice noodles dried in step S5 and bagging them to form finished products.

[0038] Example 1

[0039] This embodiment is substantially the same as Comparative Example 1, except that the rice noodles are made from the following materials in a mass ratio: mixed flour (indica rice flour, corn starch, wheat flour): pea protein = 1:0.1, and the sample is labeled PPI10.

[0040] Example 2

[0041] This embodiment is substantially the same as Comparative Example 1, except that the rice noodles are made from the following materials in a mass ratio: mixed flour (indica rice flour, corn starch, wheat flour): arabinogalactan = 1:0.002, and the sample is labeled AG0.2.

[0042] Example 3

[0043] This embodiment is substantially the same as Comparative Example 1, except that the rice noodles are made from the following materials in a mass ratio: mixed flour (indica rice flour, corn starch, wheat flour): arabinogalactan = 1:0.004, and the sample is labeled AG0.4.

[0044] Example 4

[0045] This embodiment is substantially the same as Comparative Example 1, except that the rice noodles are made from the following materials in a mass ratio: mixed flour (indica rice flour, corn starch, wheat flour): arabinogalactan = 1:0.006, and the sample is labeled AG0.6.

[0046] Example 5

[0047] This embodiment is substantially the same as Comparative Example 1, except that the rice noodles are made from the following materials in a mass ratio: mixed flour (indica rice flour, corn starch, wheat flour): pea protein: arabinogalactan = 1:0.1:0.002, and the sample is labeled PPI10-AG0.2.

[0048] Example 6

[0049] This embodiment is substantially the same as Comparative Example 1, except that the rice noodles are made from the following materials in a mass ratio: mixed flour (indica rice flour, corn starch, wheat flour): pea protein: arabinogalactan = 1:0.1:0.004, and the sample is labeled PPI10-AG0.4.

[0050] Example 7

[0051] This embodiment is substantially the same as Comparative Example 1, except that the rice noodles are made from the following materials in a mass ratio: mixed flour (indica rice flour, corn starch, wheat flour): pea protein: arabinogalactan = 1:0.1:0.006, and the sample is labeled PPI10-AG0.6.

[0052] To verify the practical effect of the present invention, the following are comparative experimental methods and results:

[0053] 1. Effects of different improvers on the cooking quality of rice noodles

[0054] 1. Experimental methods

[0055] (1) Determination of the optimal cooking time: Weigh 50.0 g of rice noodles and place them in 500 mL of boiling water. Continue cooking with a stopwatch. Samples are taken starting at 7 min and then every 30 s. Each time, one noodle is sampled. Press the noodle with a transparent glass plate. The time when no white core remains is the optimal cooking time.

[0056] (2) Breakage rate: Take 20 rice noodles and steam them in 1000 mL of boiling water. After the optimal cooking time is reached, remove them, rinse them with cold water for 30 seconds, and drain them on a sieve for 5 minutes. Weigh the rice noodles with a length of less than 10 cm and greater than 10 cm (including 10 cm) respectively, and calculate the breakage rate of rice noodles according to the following formula.

[0057]

[0058] Where m1 is the mass of rice noodles less than 10 cm in length, g;

[0059] m2 is the mass of rice noodles with a length greater than 10 cm (including 10 cm), in g.

[0060] (3) Cooking loss rate and rehydration rate: Take 5 rice noodles and place them in 250 mL of water. Cook until the optimal cooking time has elapsed, remove them, drain for 3 minutes, and weigh them. The ratio of the weight of the sample before and after rehydration is the water absorption rate. Dry the remaining soup to a constant weight, and calculate the cooking loss rate according to the following formula:

[0061]

[0062] 2. Experimental results:

[0063] According to Table 1 and Figure 1 The results showed that the addition of pea protein and arabinogalactan significantly reduced the cooking loss and breakage rate of rice noodles, shortened the rehydration time, and increased the water absorption rate of rice noodles. This is because pea protein can intervene in the gelation process of starch and promote the rearrangement of starch molecular chains, strengthening the porous network structure within the starch gel, improving the water absorption capacity of rice noodles and accelerating the penetration of water molecules into protein and starch granules. Compared with the control group, when pea protein and arabinogalactan acted synergistically (PPI10-AG0.4), the water absorption rate was significantly improved due to the combined water locking of the pea protein gel network and the hydrophilic groups of arabinogalactan. The cooking loss was reduced from 10.47% to 5.84%. At the same time, the breakage rate was also significantly reduced, and the rice noodles almost did not break when pea protein and arabinogalactan were added together.

[0064] Table 1 Effects of improvers on cooking characteristics of rice noodles

[0065]

[0066] Note: Different letters in the same column indicate significant differences between values ​​(P < 0.05)

[0067] 2. Effects of different improvers on rice noodle color

[0068] 1. Experimental methods:

[0069] The rice noodles were crushed by a grinder, passed through a 100-mesh sieve, and then measured using a colorimeter. * Represents brightness, a * Represents red and green values, b * Represents the yellow-blue value.

[0070] 2. Experimental results:

[0071] According to the results in Table 2, with the addition of the modifier, L * The value decreases, a * Value and b * As the value increases, the overall color changes are more acceptable. * Value and b * The increase in the value is partly due to the color of the pea protein itself, and partly due to the addition of the modifier, which causes the rice noodles to undergo a Maillard reaction during high-temperature extrusion, resulting in browning and yellowing.

[0072] Table 2 Chromaticity of rice noodles with different improvers

[0073]

[0074] Note: Different letters in the same column indicate significant differences between values ​​(P < 0.05)

[0075] 3. Effects of different improvers on the texture characteristics of rice noodles

[0076] 1. Experimental methods:

[0077] The textural properties of rehydrated rice noodles with different improvers were studied using a texture analyzer (TA). All samples were measured at the optimal cooking time, and all experiments were completed within 15 minutes after rehydration.

[0078] (1) Texture Profile Analysis (TPA) experimental parameter settings: probe P / 36R, pre-test speed: 2.00 mm / sec, test speed: 1.00 mm / sec, post-test speed: 1.00 mm / sec, target mode: strain: 50.00%, time: 3.00 sec, trigger force: 5.00 g. During the measurement, 6 rice noodles were placed on the stage at equal intervals, perpendicular to the test blade and parallel to the side of the stage. This was repeated 3 times, and the average value was taken. The measured indicators included hardness, viscosity, elasticity, cohesion, adhesiveness, and chewiness.

[0079] (2) Tensile properties: Probe A / SPR, test speed: 2.00 mm / sec, post-test speed: 10.00 mm / sec, distance: 80.000 mm. Repeat the measurement three times and take the average value.

[0080] (3) Shear properties: The test parameters for shear properties were set as a pre-test speed of 2 mm / s, a test speed of 0.17 mm / s, a post-test speed of 2 mm / s, a trigger force of 15 g, and a deformation of 80%. Three to five rice noodle samples of uniform thickness were selected for each test, and the average value was calculated after at least three measurements.

[0081] 2. Experimental results:

[0082] Texture is the most important quality of rice noodles. High hardness and high elasticity are both ideal quality characteristics of rice noodles. Figure 2 It can be seen that with the addition of the improver, the hardness of the rice noodles gradually increased, the elasticity and chewiness gradually increased, and the cohesion did not change significantly. The addition of pea protein significantly reduced the hardness to 242.70±21.17g, which may be because the flexible gel network of pea protein replaced part of the rigid structure of starch. Compared with the control group, the synergistic effect of pea protein and arabinogalactan (PPI10-AG0.4) significantly increased the hardness of rice noodles, from 327.02±21.50g to 675.03±22.19g, an increase of 51.60%, the chewiness increased from 196.11±50.05 to 259.01±45.28, an increase of 24.28%, and the elasticity increased by 10.26%. The reason is that the high water holding capacity of arabinogalactan can make the rice noodle structure more compact, and the pea protein and arabinogalactan compound group synergistically forms stronger cross-links due to the synergistic formation of protein and polysaccharide. Overall, the addition of PPI and AG significantly improved the texture characteristics of rice noodles.

[0083] Table 3 Texture characteristics of rice noodles with different improvers

[0084]

[0085] Note: Different letters in the same column indicate significant differences between values ​​(P < 0.05)

[0086] 4. Effects of different improvers on the short-range ordered structure of rice noodles

[0087] 1. Experimental methods:

[0088] The molecular structure of rice noodles was measured using Fourier transform infrared spectroscopy. 1 mg of sample was mixed with potassium bromide powder in a mortar at a ratio of 1:100 (w / w), ground into a transparent sheet, and analyzed by infrared spectroscopy at a wave number of 4000-400 cm -1 , with a resolution of 8cm -1 .

[0089] 2. Experimental results:

[0090] Effects of modifiers on the short-range ordered structure of rice noodles Figure 3The infrared spectrum data showed that all samples had a wavelength of 3300-3400 cm -1 The infrared spectra of different rice noodles showed strong OH stretching vibration peaks. No new absorption peaks were generated in the infrared spectra of different rice noodles, indicating that no new functional groups were introduced. After adding the modifier, the absorption peak shifted to the blue, indicating that the modifier may have caused the formation of hydrogen bonds in the starch molecules or increased the binding of water molecules, thereby reducing the content of free hydroxyl groups. After the pea protein was co-treated with arabinogalactan (PPI10-AG0.4), the wavelength was increased from 3316.7 cm -1 Blue shift to 3312.7cm -1 .

[0091] 1047cm -1 The corresponding ordered structure in starch molecules, 1022 cm -1 corresponds to an amorphous structure, and its ratio R 1047 / 1022 It can be used to quantitatively characterize the short-range ordered structure of starch. 1047 / 1022 The increase in the value indicates an enhanced short-range order in the starch molecules. This is likely due to the physical interactions (hydrogen bonding or adhesion) and non-covalent interactions between pea protein and starch, which reduce the breakdown of starch granules and water swelling during extrusion, promote hydrogen bonding between starch granules, and enhance the short-range order of the starch molecules. Arabinogalactan, rich in hydrophilic groups, binds to starch through hydrogen bonds, promoting the formation of a more regular helical conformation and thus improving the short-range order of the starch molecules. The short-range order of starch in rice noodles containing both arabinogalactan and pea protein increased significantly, from 1.022 to 1.125, 1.135, and 1.057, respectively.

[0092] 5. Analysis of digestibility characteristics and estimated GI values ​​of rice noodles with different improvers

[0093] 1. Experimental methods:

[0094] (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, 0.5mol / L acetic acid buffer solution with pH=5.2 and 10mL of mixed enzyme solution containing saccharifying enzyme (15U / mL) and α-amylase (290U / mL). Place the conical flask in a water bath at 37℃ and shake at a speed of 130rpm to perform enzymatic hydrolysis and start timing. Accurately draw 1mL of enzymatic hydrolysis solution at 0, 20 and 120min time periods, place it in a centrifuge tube, add 4mL of anhydrous ethanol to inactivate it, centrifuge at 4000rpm for 10min, use a glucose determination kit and an enzyme reader to measure the absorbance of the supernatant at 505nm, and calculate the content of rapidly digestible starch, slowly digestible starch and resistant starch according to the following formula.

[0095]

[0096] Where: G 20 : Glucose content in digestive juice at 20 min (mg).

[0097] F G : Free glucose content in digestive juice (mg)

[0098] G 120 :Glucose content in digestive fluid at 120 min (mg)

[0099] TS: total starch content (mg).

[0100] (2) Estimated GI value:

[0101] ①Sample preparation: Same as experimental method ①

[0102] ② Oral chewing simulation: Refer to the method of Gawlik-Dziki et al. with appropriate adjustments. Place 1 g of treated sample in a conical flask, add 10 mL of pH 6.5 phosphate buffer solution containing salivary amylase, and gently tap with a mortar for 15 seconds. Add 5 glass beads and shake in a 37°C water bath for 10 minutes.

[0103] ③ Gastric digestion simulation: adjust the pH to 1.2 with 5 M HCl, then add 10 mL of 0.03 M NaCl solution (pH = 1.2) containing pepsin, and shake in a 37°C water bath for 30 min.

[0104] ④ Intestinal digestion simulation: Use 1 M NaOH to adjust the pH to 7.0, add 10 mL of intestinal fluid (add 0.05 g of pancreatic enzyme, 0.3 g of porcine bile salt, and 0.3 g of saccharifying enzyme to 100 mL of phosphate buffer solution), 5 mL of 120 mM NaCl solution, and 5 mL of 120 mM KCl. Shake in a 37°C water bath for 180 min. Accurately draw 1 mL of sample at 10, 20, 30, 45, 60, 90, 120, 150, and 180 min, respectively, into a centrifuge tube containing 4 mL of anhydrous ethanol, and centrifuge at 5000 rpm for 10 min.

[0105] 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 at different time periods.

[0106] ⑥Calculation method: Calculate the hydrolysis rate of starch based on 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 equation C t =C ∞ (1-e -kt) was used for first-order kinetic fitting, and Origin software was used for model fitting and mapping, and the hydrolysis equilibrium constant k was calculated.

[0107] The area under the digestion curve (AUC) was calculated by the following formula:

[0108]

[0109] Where: C t : starch hydrolysis rate at time t; C ∞ : Final starch hydrolysis rate; t f : total digestion reaction time (180 min); t0: digestion start time (0 min); k: kinetic constant

[0110] The hydrolysis index (HI) is calculated by the following formula:

[0111]

[0112] Using white bread as a reference, calculate the GI of rice noodles using the following formula:

[0113] GI=0.862HI+8.198

[0114] 2. Experimental results:

[0115] From the digestion characteristics diagram ( Figure 4 ) As can be seen, compared with the control group, the addition of the improver gradually reduced the rapidly digestible starch content of rice noodles, while correspondingly increasing the slowly digestible starch and resistant starch contents. Rice noodles supplemented with pea protein showed a significant decrease in RDS content, from 58.21% to 52.12%. This may be due to the protein adhering to the starch surface, hindering access and enzymatic degradation by amylase. Furthermore, interactions between the protein and starch may further reduce the availability of starch as a substrate for amylase digestion, inhibiting starch digestion. Rice noodles supplemented with arabinogalactan, through the addition of the hydrocolloid, enhanced hydrogen bonding between starch molecules, causing some amylose molecules to form double helical structures, thereby increasing the RS content. Rice noodles supplemented with the improver PPI10-AG0.4 decreased the RDS content from 58.21% to 48.92%, increased the SDS content from 23.24% to 25.38%, and increased the RS content from 18.45% to 25.70%.

[0116] From the starch hydrolysis curve ( Figure 5 ) and Table 4, the addition of improvers can effectively reduce the estimated GI value (eGI) of rice noodles and reduce the glycemic ability of rice noodles.

[0117] Table 4 Changes in starch digestion kinetic parameters for different formulas

[0118]

[0119] 6. Scanning electron microscopy analysis of rice noodles with different improvers

[0120] 1. Experimental methods:

[0121] Rice noodles cooked for the optimal cooking time were drained of surface moisture, frozen at -80°C for 8-10 hours, and then freeze-dried in a freeze dryer for 72 hours. The network structure of the rice noodles was observed using a scanning electron microscope at a test voltage of 8 kV and a current of 8 μA.

[0122] 2. Experimental results:

[0123] Depend on Figure 6 Scanning electron microscopy images show that while the control group exhibited visible cracks and holes on the surface, the addition of the PPI10-AG0.4 modifier significantly altered the internal morphology of the rice noodles. The pea protein formed a continuous gel membrane that encapsulated the starch granules, while the arabinogalactan filled the gaps, resulting in a smoother surface and reduced porosity. The internal network structure of the rice noodles became more compact and dense, which increased the gel strength.

[0124] The above disclosure is only a preferred embodiment of the present invention, and it is certainly not intended to limit the scope of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing nutritious rice noodles with high water holding capacity, characterized in that: The following steps are included: Step S1: Indica rice flour, corn starch, and wheat flour are mixed evenly to prepare a mixed powder, and the mixed powder and the improver are weighed according to weight, put into a mixer, and mixed evenly for later use; Step S2: Extruding the mixture prepared in step S1 into rice noodles using a twin-screw extruder at high temperature; Step S3: placing the rice noodles extruded in step S2 into a constant temperature and humidity incubator for static placement; Step S4: putting the rice noodles prepared in step S3 into cold water to make them into thin strips; Step S5: sending the rice noodles after being shredded in step S4 into an oven for hot air drying; Step S6: cutting the rice noodles dried in step S5 and bagging them to form finished products.

2. The method for preparing nutritious rice noodles with high water holding capacity according to claim 1, wherein: In step S1, the improving agent is pea protein.

3. The method for preparing high water-holding nutritious rice noodles according to claim 2, wherein: The addition ratio of mixed powder to pea protein is 1:0.

1.

4. The method for preparing nutritious rice noodles with high water holding capacity according to claim 1, wherein: In step S1, the improving agent is arabinogalactan.

5. The method for preparing nutritious rice noodles with high water holding capacity according to claim 4, wherein: The addition ratio of the mixed powder to arabinogalactan is 1:0.002-0.

006.

6. The method for preparing nutritious rice noodles with high water holding capacity according to claim 1, wherein: In step S1, the improver is a mixture of pea protein and arabinogalactan.

7. The method for preparing nutritious rice noodles with high water holding capacity according to claim 6, wherein: The mixing ratio of pea protein to arabinogalactan is 0.1:0.002-0.

006.

8. The method for preparing nutritious rice noodles with high water holding capacity according to claim 7, wherein: The adding ratio of mixed powder to improver is 1:0.1:0.002-0.

006.

9. The method for preparing nutritious rice noodles with high water holding capacity according to claim 1, wherein: In step S3, the conditions of the constant temperature and humidity incubator are 30° C. and 90% humidity, and the incubator is left to stand for 12 hours.

10. A nutritious rice noodle with high water holding capacity, obtained by the method for preparing nutritious rice noodle with high water holding capacity according to any one of claims 1 to 9.

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