Rapidly rehydrated dry rice noodles and preparation method thereof

Abstract

The invention relates to quickly rehydrated dry rice noodles and a preparation method thereof, and belongs to the technical field of food processing. The quick-rehydration dry rice noodles are obtained by mixing rice flour, sodium chloride and water, curing, extruding, aging, pre-drying, dialyzing and freeze-drying. In the preparation process of the dry rice noodles disclosed by the invention, sodium chloride is added, pre-dried and dialyzed to remove sodium chloride, so that a porous structure is generated in the rice noodles, water can enter the rice noodles quickly and conveniently, the rehydration time is remarkably shortened, and the salting-out effect of the sodium chloride can optimize the quality of the rice noodles; the mechanical properties and sensory indexes of the rice noodles are improved. The method is simple in process, sodium chloride is low in cost and can be recycled after dialysis and drying, and the high-quality dry rice noodles capable of being rehydrated rapidly can be obtained.

Description

Technical Field

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

[0002] Starch-based gel foods such as rice noodles are popular among consumers for their flexible texture and smooth taste. Dry rice noodles are often used in various pre-packaged foods due to their long shelf life and ease of storage and transportation. The main component of rice noodles is rice starch, which forms a dense three-dimensional network through gelatinization and subsequent aging. While this contributes to the excellent quality of rice noodles, it also presents challenges during the rehydration process. Commercially available dry rice noodles with a diameter of approximately 1.5 mm have a rehydration time of approximately 10-15 minutes. Excessively long rehydration times not only prolong cooking time but also result in large cooking losses and poor tensile properties, which runs counter to modern consumers' demand for convenient, high-quality foods. Therefore, the long rehydration time of dry rice noodles has become a key technical challenge hindering their development in the market.

[0003] An effective solution to the rice noodle rehydration challenge is to increase the porosity or looseness of the rice noodle starch network. Common approaches include physical methods to increase the internal porosity of rice noodles (freeze-drying, deep-frying, etc.), the addition of soluble and foaming food additives (erythritol, gelatin, etc.), and enzymatic hydrolysis (using enzymes to increase the branching of rice starch). For example, deep-frying rapidly evaporates the internal water content of noodles, forming a porous structure, but this method can severely degrade the gel quality. The use of additives such as sugar alcohols and maltodextrin can significantly reduce the density of starch-based gels. This process creates porosity through dissolution and leaching, which in turn accelerates the rehydration of dried gels. However, the rehydration process can lead to cooking losses and turbidity in the soup. The application of 1,4-α-glucan branching enzymes helps minimize the opportunities for starch molecules to reorganize into structured arrangements. This enhances the porosity of the rice noodle gel network and significantly shortens the rehydration time of dry rice noodles. However, this approach involves complex enzymatic hydrolysis processes and expensive materials, making it challenging to apply in industrial applications due to its high cost. Therefore, a simple and low-cost method for preparing dry rice flour is provided, so that the prepared dry rice flour has the characteristics of rapid rehydration and high quality, which is of great significance to the field. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a simple, low-cost preparation method for quickly rehydrating dry rice noodles, which can significantly shorten the rehydration time of the dry rice noodles and improve the quality of the dry rice noodles.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing quickly rehydrated dry rice noodles, comprising the following steps:

[0007] The rice flour, sodium chloride and water are mixed, matured and squeezed into strips, aged, pre-dried, dialyzed and freeze-dried;

[0008] The mass ratio of rice flour to sodium chloride is (480-520): (100-155).

[0009] Preferably, the mass ratio of rice flour to water is (480-520):(480-520).

[0010] Preferably, the aging is performed by heating at 95-105° C. for 2.5-5 minutes.

[0011] Preferably, the aging is performed by standing at 25-35° C. for 8-12 hours.

[0012] Preferably, the aging is carried out in a closed environment.

[0013] Preferably, the pre-drying is performed at 43-55° C. for 0.8-1.2 h.

[0014] Preferably, the dialysis is performed by soaking the pre-dried rice flour in water, and the mass ratio of the pre-dried rice flour to water is (200-250): (500-600).

[0015] Preferably, the soaking is performed 4 to 6 times, and the soaking time for each soaking is 9 to 20 minutes.

[0016] Preferably, the freeze-drying is freeze-drying to a water content of less than 14%.

[0017] The present invention also provides the quickly rehydrated dry rice noodles prepared by the preparation method.

[0018] Beneficial effects of the present invention:

[0019] The present invention provides a method for preparing rapidly rehydrated dry rice noodles. By adding sodium chloride (NaCl) and then removing the sodium chloride through dialysis, a porous structure is created within the rice noodles, facilitating faster water entry and significantly shortening the rehydration time. The salting-out effect of the sodium chloride can also optimize the quality of the rice noodles, improving their mechanical properties and sensory indicators. The present invention has a simple process, low sodium chloride cost, high solubility, and is easily dissolved when added to the rice noodles during soaking and dialysis, causing minimal damage to the starch gel network. Furthermore, the method is reusable and environmentally friendly, thereby producing high-quality rapidly rehydrated dry rice noodles.

[0020] The present invention effectively removes sodium chloride from rice noodles through a dialysis process. Multi-scale characterization and practical application verification confirm that the residual amount is within a safe and controllable range. Structural characterization revealed that the XRD pattern of the dialyzed rice noodles showed no characteristic NaCl crystallization peaks, and SEM microstructures exhibited a uniform, porous morphology with no salt crystals attached, indicating that the crystalline sodium chloride had been fully dissolved. Functional verification also demonstrated that residual sodium chloride rapidly dissolves during rehydration and, based on sensory evaluation, exhibits only a slight salty taste. This demonstrates that the rapidly rehydrating dry rice noodles prepared by the present invention are both production-feasible and safe for consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the rehydration time of dry rice noodles in each group. The same letters among the groups in the bar graph indicate no significant difference (P>0.05), and the absence of the same letters indicates a significant difference (P<0.05).

[0022] Figure 2 The mechanical properties of dry rice noodles in each group after rehydration.

[0023] Figure 3 Shown are the XRD patterns of dry rice noodles in each group.

[0024] Figure 4 The cross-sectional microstructures of each group of dry rice noodles are shown in the figure. The first row shows the cross-sectional morphology at 50 times magnification (scale bar 100 μm), the second row shows the cross-sectional morphology at 200 times magnification (scale bar 100 μm), and the third row shows the cross-sectional morphology at 500 times magnification (scale bar 10 μm). DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing quickly rehydrated dry rice noodles, comprising the following steps:

[0026] The rice flour, sodium chloride and water are mixed, matured and squeezed into strips, aged, pre-dried, dialyzed and freeze-dried;

[0027] The mass ratio of rice flour to sodium chloride is (480-520): (100-155).

[0028] In the present invention, the mass ratio of the rice flour to the sodium chloride is preferably 480:100, 480:120, 480:140, 480:150, 480:155, 490:100, 490:120, 490:140, 490:150, 490:155, 500:100, 500:120, 500:140, 500:150, 500:155, 510:100, 510:120, 510:140, 510:150, 510:155, 520:100, 520:140, 520:150 or 520:155. The mass ratio of rice flour to water is preferably (480-520):(480-520), more preferably 480:480, 480:500, 480:520, 500:480, 500:490, 500:520, 520:480, 520:500, or 520:510. In the present invention, the sodium chloride is preferably edible sodium chloride. The sources of the rice flour, sodium chloride, and water are not particularly limited, and conventional commercial products in the art can be used.

[0029] The present invention adds sodium chloride and then removes the sodium chloride through dialysis, thereby not only generating a porous structure inside the rice noodles to facilitate faster entry of water and significantly shorten the rehydration time, but also the salting-out effect of the sodium chloride can optimize the quality of the rice noodles, thereby improving the mechanical properties and sensory indicators of the rice noodles.

[0030] In the present invention, rice flour, sodium chloride and water are mixed to obtain mixed rice slurry. The present invention has no special limitation on the mixing method, and conventional mixing methods in the art can be used. The obtained mixed rice slurry is matured and extruded, and the maturation is preferably heated at 95-105°C for 2.5-5 minutes, and the maturation temperature is more preferably 95°C, 98°C, 100°C, 102°C or 105°C. The maturation time is more preferably 2.5 minutes, 3 minutes, 4 minutes or 5 minutes, and then extruded. The present invention has no special requirements on the caliber of the extrusion, and the conventional extrusion caliber in the art can be selected. In one embodiment, an extrusion caliber of 1.5 mm can be selected. The present invention has no special limitation on the equipment for maturation and extrusion, and conventional maturation and extrusion equipment in the art can be used. In one embodiment, a single-screw extruder can be selected.

[0031] In the present invention, the rice noodles obtained after extrusion are aged. Before the aging, the rice noodles are preferably cooled to 25-35°C, more preferably cooled to 25°C, 28°C, 30°C, 33°C or 35°C. After cooling, the aging is carried out, and the aging is preferably left to stand at 25-35°C for 8-12 hours. The aging temperature is more preferably 25°C, 28°C, 30°C, 33°C or 35°C, and the aging time is more preferably 8 hours, 9 hours, 10 hours, 11 hours or 12 hours. The aging process can rearrange the starch molecules in the rice noodles, thereby improving the taste and texture characteristics of the rice noodles. The aging is preferably carried out in a closed environment. The present invention has no special requirements for the closed environment. A conventional closed environment in the art can be used. In some embodiments, it can be sealed with plastic wrap or placed in a sealed container. Aging in a closed environment can minimize the loss of moisture, ensure the full occurrence of the aging and regeneration process of the rice noodles, and ensure that the texture characteristics of the rice noodles are good.

[0032] In the present invention, after the rice noodles are aged, the aged rice noodles are preferably taken out of the closed environment and pre-dried. The pre-drying is preferably dried at 43 to 55°C for 0.8 to 1.2 hours. The pre-drying temperature is more preferably 43°C, 45°C, 48°C, 50°C, 53°C or 55°C, and the pre-drying time is more preferably 0.8h, 0.9h, 1.0h, 1.1h or 1.2h. The moisture content of the dried rice noodles is between 35% and 55%. By adding the pre-drying step before dialysis, the mouthfeel of the prepared rice noodles is further improved, the firmness and taste are improved, and the tensile strain is enhanced, thereby improving the toughness of the rice noodles. After pre-drying, dialysis is performed, and the dialysis is preferably performed by soaking the pre-dried rice flour in water. The mass ratio of the pre-dried rice flour to water is preferably (200-250): (500-600), more preferably 200:500, 200:550, 200:600, 230:500, 230:550, 230:600, 250:500, 250:550 or 250:600. The number of soaking times is preferably 4-6 times, more preferably 4 times, 5 times or 6 times, and the time of each soaking is preferably 9-20 minutes, more preferably 9 minutes, 10 minutes, 13 minutes, 15 minutes, 18 minutes or 20 minutes. The temperature of the water used for soaking is preferably 25-45°C, more preferably 25°C, 30°C, 35°C, 40°C or 45°C. Dialysis can remove salt, form a porous structure inside the rice noodles, and shorten the rehydration time of the rice noodles. In addition, the XRD spectrum of the rice noodles after dialysis using the dialysis method of the present invention does not show a characteristic crystallization peak of NaCl, and the SEM microstructure shows a uniform porous morphology without salt crystals attached, indicating that the dialysis method of the present invention can fully dissolve sodium chloride.

[0033] In the present invention, after dialysis, the rice noodles are fished out and drained of water and then freeze-dried. The freeze-drying is preferably freeze-dried to a water content of less than 14%. The present invention has no special limitation on the freeze-drying method and conventional freeze-drying methods in the art can be used. In some embodiments, freeze-drying at -60°C to -80°C for 48 to 72 hours can be selected. In some embodiments, the freeze-drying temperature is -60°C, -65°C, -70°C, -75°C or -80°C, and the freeze-drying time is 48 hours, 52 hours, 56 hours, 60 hours, 64 hours, 68 hours or 72 hours to obtain storage-stable dry rice noodles.

[0034] The present invention also provides quickly rehydrated dry rice noodles prepared by the preparation method. The quickly rehydrated dry rice noodles of the present invention have a fast rehydration time of only about 5 minutes, which is significantly shortened compared to the 10-15 minutes required by existing dry rice noodles. At the same time, the sensory indicators and texture properties of the rice noodles after rehydration are also significantly improved. The rice noodles are not only stretch-resistant, but also have a smooth and shiny surface, are elastic, have a smooth taste, and do not feel sticky to the teeth.

[0035] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0036] In the following examples, unless otherwise specified, all methods are conventional.

[0037] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0038] Example 1

[0039] A quick-rehydration dry rice noodle is prepared by the following preparation method:

[0040] The main ingredients are mixed: 500g of rice flour, 150g of edible sodium chloride, and 500g of water are thoroughly mixed to obtain mixed rice milk;

[0041] Matured extrusion: Pour the mixed rice slurry into a single-screw extruder, heat the rice slurry at 100°C for 3 minutes, and extrude it through an extrusion outlet with a diameter of 1.5 mm;

[0042] Aging: After extrusion, the rice noodles are cooled to 30°C, sealed with plastic wrap to reduce moisture loss, and aged at 30°C for 10 hours.

[0043] Pre-drying: Remove the plastic wrap from the aged rice noodles and place them in a hot air drying oven at 45°C for 1 hour;

[0044] Dialysis: Take 230g of pre-dried rice flour and dialyze it with 550g of 30℃ water. Repeat 4 times, 10min each time, to remove excess sodium chloride.

[0045] Freeze-drying: Drain the dialyzed rice flour and freeze-dry it at -70°C for 60 hours to reduce the moisture content to less than 14%, thereby producing dry rice flour. The finished rice flour is then sorted and packaged.

[0046] Example 2

[0047] A quick-rehydration dry rice noodle is prepared by the following preparation method:

[0048] Main ingredients: 480g of rice flour, 100g of edible sodium chloride, and 520g of water are thoroughly mixed to obtain mixed rice milk;

[0049] Matured extrusion: Pour the mixed rice slurry into a single-screw extruder, heat the rice slurry at 95°C for 2.5 minutes, and extrude it through an extrusion outlet with a diameter of 1.5 mm;

[0050] Aging: After the extruded rice noodles are cooled to 25°C, they are sealed with plastic wrap to reduce moisture loss and aged at 25°C for 8 hours.

[0051] Pre-drying: Remove the plastic wrap from the aged rice noodles and place them in a hot air drying oven at 43°C for 0.8h;

[0052] Dialysis: Take 200g of pre-dried rice flour and dialyze it with 500g of 25℃ water. Repeat 5 times, 9 minutes each time, to remove excess sodium chloride.

[0053] Freeze-drying: Drain the dialyzed rice flour and freeze-dry it at -60°C for 48 hours to reduce the moisture content to less than 14%, thereby producing dry rice flour. The finished rice flour is then sorted and packaged.

[0054] Example 3

[0055] A quick-rehydration dry rice noodle is prepared by the following preparation method:

[0056] Main ingredients: 520g of rice flour, 155g of edible sodium chloride, and 480g of water are thoroughly mixed to obtain mixed rice milk;

[0057] Matured extrusion: Pour the mixed rice slurry into a single-screw extruder, heat the rice slurry at 105°C for 5 minutes, and extrude it through an extrusion outlet with a diameter of 1.5 mm;

[0058] Aging: After the extruded rice noodles are cooled to 35°C, they are sealed with plastic wrap to reduce moisture loss and aged at 35°C for 12 hours.

[0059] Pre-drying: Remove the plastic wrap from the aged rice noodles and place them in a hot air drying oven at 55°C for 1.2 hours;

[0060] Dialysis: Take 250g of pre-dried rice flour and dialyze it with 600g of 45℃ water. Repeat 6 times, 20min each time, to remove excess sodium chloride.

[0061] Freeze-drying: After the dialyzed rice flour is drained of water, freeze-dried at -80°C for 72 hours to reduce the moisture content to less than 14%, to prepare dry rice flour, which is then sorted and packaged to obtain the finished rice flour product.

[0062] Comparative Example 1

[0063] A dry rice noodle is different from Example 1 in that edible sodium chloride is not added when the main ingredients are compounded, there are no pre-drying and dialysis steps, the aged rice noodles are directly freeze-dried, and the rest are the same as Example 1.

[0064] Comparative Example 2

[0065] A dry rice noodle is different from Example 1 in that edible sodium chloride is not added when the main ingredients are compounded, there is no pre-drying step, the aged rice noodles are directly dialyzed, and the rest are the same as Example 1.

[0066] Comparative Example 3

[0067] A dry rice noodle is different from that in Example 1 in that edible sodium chloride is not added when the main ingredients are compounded, and the rest are the same as in Example 1.

[0068] Comparative Example 4

[0069] A dry rice noodle is different from Example 1 in that no pre-drying step is performed, and the aged rice noodle is directly dialyzed. Other steps are the same as Example 1.

[0070] Test Example 1

[0071] Determine the rehydration time of the dry rice flour prepared in Example 1 and Comparative Examples 1-4

[0072] Rehydration time determination method: Place 35g of dry rice noodles in boiling water for rehydration. Starting from the third minute, remove a piece of rice noodle every 30 seconds and press it with a glass plate until the hard core is no longer visible. The time at which the rice noodle is removed is recorded as the optimal rehydration time.

[0073] The optimal rehydration time of each group of dry rice noodles is shown in Figure 1 . Figure 1 The effects of different processes such as adding edible NaCl, dialysis and pre-drying on the rehydration time of freeze-dried rice noodles are shown. Compared with Comparative Example 1, the rehydration time of Comparative Example 2 and Comparative Example 3 increased from 10.25±0.14min to 13.00±0.09min and 14.00±0.02min, respectively. This shows that dialysis and pre-drying further prolonged the rehydration time. In contrast, the rehydration time of the dry rice noodles prepared using Example 1 was much shorter. Figure 1As can be seen from the results, the rehydration time of Comparative Example 4 was only 5.15±0.25 min, while the rehydration time of Example 1 was 5.20±0.25 min, with no significant difference between the two. In contrast, the rehydration time of Example 1 was shortened by 49.27% ​​compared with Comparative Example 1, and by 62.86% compared with Comparative Example 3. This indicates that the rehydration time of dry rice noodles prepared by adding sodium chloride during the preparation of rice noodles and then dialyzing to remove the sodium chloride was significantly shortened, greatly improving the rehydration speed.

[0074] Test Example 2

[0075] The dry rice noodles obtained in Example 1 and Comparative Examples 1-4 were boiled to their respective optimal rehydration times (obtained in Test Example 1) and subjected to sensory evaluation.

[0076] Evaluation Method: Ten professional graders evaluated the firmness, elasticity, smoothness, taste, surface texture, stickiness, and color of the rehydrated rice noodles according to the evaluation criteria shown in Table 1 below. The average score of the 10 professional graders was used as the final evaluation result.

[0077] Table 1 Sensory evaluation standards

[0078]

[0079] The sensory evaluation results are shown in Table 2. As can be seen from Table 2, the sensory evaluation results of the dry rice noodles prepared in Example 1 of the present invention are better than those of Comparative Examples 1-4. Compared with Comparative Example 1, the present invention adds sodium chloride and adds pre-drying and dialysis steps after aging, so that the rice noodles have moderate firmness, improve the elasticity, smoothness and taste of the rice noodles, improve its surface state, color and sticky feeling, and improve the sensory effect of the dry rice noodles as a whole. However, Comparative Example 4 lacks the pre-drying step and sodium chloride cannot be completely dialyzed, and its firmness and taste are not as good as the rice noodles obtained in Example 1.

[0080] Table 2 Sensory evaluation results

[0081] sensory Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Firmness 6 7 7 7 9 elasticity 15 15 16 20 19 Smoothness 14 16 18 19 20 Taste 20 20 20 9 14 Surface state 7 9 9 9 9 Sticky feeling 5 8 9 9 9 Color 8 9 9 9 9 Total score 75 84 88 82 89

[0082] Test Example 3

[0083] Determination of the mechanical properties of the dry rice noodles prepared in Example 1 and Comparative Examples 1-4

[0084] Determination method: Take 15g of dry rice noodles and boil them in boiling water until the optimal rehydration time (obtained in Test Example 1) and then measure the mechanical properties. Take one piece of rice noodles for each measurement and rehydrate them completely. Use a texture analyzer equipped with an A / TG tensile fixture to analyze and evaluate the tensile properties of the rice noodles after rehydration. The experimental settings include a speed of 3mm / s before the test, a test speed of 1mm / s, and a speed of 3mm / s after the test. The displacement method is used as a trigger, and the trigger force is 5g. The sample is set as a cylinder with a height of 10mm and a diameter of 1.5mm. The stress-strain curve is obtained by averaging the results of five separate measurements.

[0085] Test results are shown in Figure 2 And Table 3, Figure 2 Table 3 shows the effects of dialysis and pre-drying after adding edible NaCl on the tensile strength (stress) and elongation at break (strain) of dry rice flour. Compared with Comparative Example 1, dialysis, pre-drying, and the addition of sodium chloride primarily reduced the tensile strength of the rehydrated freeze-dried rice flour and increased its elongation at break. After rehydration of the dry rice flour of Example 1 after adding NaCl, pre-drying, and dialysis, the tensile strength and elongation at break decreased from 0.34±0.014 kPa and 99.09±1.36%, respectively, to 0.22±0.022 kPa and 339.05±1.52%, compared to the dry rice flour of Comparative Example 1. The tensile strength decreased by 35.3%, while the elongation at break increased by 239.96% (339.05%-99.09%). The elongation at break of the rice flour gel prepared in Example 1 after rehydration was significantly greater than that of the comparative example group, indicating that the addition of NaCl increases tensile properties. Compared with Comparative Example 4, the elongation at break of Example 1 increased by 50.27% (339.05%-288.78%), but the stress was greatly reduced, indicating that the rice noodles of Example 1 had increased toughness and improved tensile strength compared with Comparative Example 4, thereby reducing the hardness of the rice noodles and making the obtained rice noodles moderately soft and hard. This is also consistent with the results of Test Example 2 that the firmness of Example 1 was appropriate in softness and hardness.

[0086] Table 3 Mechanical properties test results

[0087] sample strain / % Stress / Kpa Comparative Example 1 <![CDATA[99.09±1.36 e ]]> <![CDATA[0.34±0.014 b ]]> Comparative Example 2 <![CDATA[133.32±2.02 d ]]> <![CDATA[0.23±0.018 c ]]> Comparative Example 3 <![CDATA[210.80±3.78 c ]]> <![CDATA[0.23±0.018 c ]]> Comparative Example 4 <![CDATA[288.78±5.78 b ]]> <![CDATA[0.46±0.019 a ]]> Example 1 <![CDATA[339.05±1.52 a ]]> <![CDATA[0.22±0.022 c ]]>

[0088] Note: In the same column of the table, the same letters between different groups indicate no significant difference (P>0.05), and different letters indicate significant difference (P<0.05).

[0089] Test Example 4

[0090] Determination of the crystallization characteristics of the dry rice flour prepared in Example 1 and Comparative Examples 1-4

[0091] Crystallization Characterization Method: The crystal structure and relative crystallinity of each dry rice flour were determined using an X-ray diffractometer. The dry rice flour was ground into a fine powder, passed through a 100-mesh sieve, adjusted to a relative humidity of 25%, and then equilibrated at 4°C for 24 hours. The experimental settings included the following parameters: scanning speed 1° / min, step width 0.02°, current 40 mA, voltage 40 kV, scanning range 4° to 40° (2θ), and CuKα radiation (λ = 1.54). As shown in formula (1), the relative crystallinity (RC) was calculated based on the ratio of the crystalline peak area in the range of 8°-28° (2θ) to the total peak area, where Ac represents the crystalline region peak area and Aa corresponds to the amorphous region peak area.

[0092]

[0093] See the results Figure 3 , Figure 3 The effects of different processes such as adding edible NaCl, dialysis and pre-drying on the crystallinity of dry rice noodles are shown. The pure rice noodles of Comparative Examples 1-3 without the addition of sodium chloride showed a B-type structure after gelatinization, with obvious peaks at 17° and 20°. However, in Comparative Example 4 and Example 1 after the addition of sodium chloride, the crystalline structure of the rice noodles changed from B-type to V-type, with a broad peak appearing near 20° and a weak broad peak appearing near 13°, and the peak area was significantly reduced. At the same time, the XRD spectrum of the rice noodles after dialysis did not show any crystalline peak other than the characteristic peak of starch. Calculations show that the crystallinity of Comparative Example 1 is 9.76%, while the crystallinity of Comparative Example 2 and Comparative Example 4 is 8.03% and 6.82%, respectively, which is a slight decrease. After pre-drying for 1 hour and then dialyzed, the crystallinity of Comparative Example 3 and Example 1 was 7.32% and 4.96%, respectively. These results indicate that the addition of sodium chloride significantly reduced the crystallinity of rice noodles, regardless of whether dialyzed or pre-dried and dialyzed, resulting in a better-tasting rice noodles compared to rice noodles without sodium chloride addition.

[0094] Test Example 5

[0095] The microstructure of the dry rice noodles prepared in Example 1 and Comparative Examples 1-4 was analyzed.

[0096] Microstructural Analysis: Scanning electron microscopy (SEM) was used to investigate the microscopic characteristics of cross-sections of dry rice noodles. SEM analysis was performed under test conditions of 5 kV and 10 μA. The dry rice noodles were broken into thin slices and secured to the sample stage with conductive tape. The slices were gold-sprayed using a SEM gold spraying machine. Cross-sectional morphology was observed at 50x, 200x, and 500x magnifications.

[0097] Figure 4The effects of different processes, such as adding edible sodium chloride, dialysis, and pre-drying, on the internal morphology of freeze-dried rice noodles are shown. The cross-sections of all samples exhibit a honeycomb structure, and the dialysis process greatly increases the internal pore structure and significantly increases the pore diameter. Compared with Comparative Example 1, the cross-sectional pore diameter of Comparative Example 2 increases from a few microns to tens of microns. After adding sodium chloride, the number and size of pores inside the rice noodles increase significantly, with pore diameters reaching tens of microns. Despite this, the network structure remains relatively uniform, and the pore walls are thinner. This effect is particularly evident in Example 1, where the pore walls become thinner, the gel network becomes more complete, and no salt crystals adhere. This phenomenon indicates that pre-drying and dialysis of the rice noodles with sodium chloride adds more pore structure to the rice noodles and strengthens the gel structure, resulting in pores of uniform size, dense distribution, and thinner walls.

[0098] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing quickly rehydrated dry rice noodles, characterized in that: The following steps are involved: The rice flour, sodium chloride and water are mixed, matured and squeezed into strips, aged, pre-dried, dialyzed and freeze-dried; The mass ratio of rice flour to sodium chloride is (480-520): (100-155).

2. The preparation method according to claim 1, characterized in that The mass ratio of rice flour to water is (480-520):(480-520).

3. The preparation method according to claim 1, characterized in that The aging is performed by heating at 95-105° C. for 2.5-5 minutes.

4. The preparation method according to claim 1, characterized in that The aging step is to stand at 25-35° C. for 8-12 hours.

5. The preparation method according to claim 1, characterized in that The aging is aging in a closed environment.

6. The preparation method according to claim 1, characterized in that The pre-drying is performed at 43-55° C. for 0.8-1.2 h.

7. The preparation method according to claim 1, characterized in that The dialysis is performed by soaking the pre-dried rice flour in water, wherein the mass ratio of the pre-dried rice flour to water is (200-250): (500-600).

8. The preparation method according to claim 7, characterized in that The soaking is performed 4 to 6 times, and the soaking time for each soaking is 9 to 20 minutes.

9. The preparation method according to claim 1, characterized in that The freeze-drying step is freeze-drying until the water content is less than 14%.

10. The quick-rehydrating dry rice flour prepared by the preparation method according to any one of claims 1 to 9.

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