Preparation method of anti-digestion dry rice noodles

Abstract

The invention relates to a preparation method of anti-digestion dry rice noodles. The preparation method comprises the following steps: washing rice, soaking and grinding into thick liquid; adding a certain amount of edible corn starch into the rice milk, adding a small amount of edible lipid (edible oil, oleic acid, linoleic acid or lauric acid), and fully stirring and uniformly mixing; heating, stirring and toughening the mixture; adding the toughened mixed slurry into a heatable extruder, heating the mixed slurry, fully gelatinizing the heated mixed slurry, and extruding the gelatinized mixed slurry from an outlet to obtain fresh wet rice noodles; aging and drying the fresh and wet rice noodles to obtain dry rice noodles. According to the method, edible lipid is added in the processing process, on one hand, the lipid is added and subjected to toughening treatment, combination of the lipid and amylose can be promoted, starch-lipid compound type resistant starch can be formed easily, the digestion resistance of the dry rice noodles is improved, on the other hand, aging of the dry rice noodles is regulated and controlled through addition of the lipid, and the digestion resistance of the dry rice noodles is improved. The rehydration time of the dry rice noodles can be shortened.

Description

Technical Field

[0001] The invention relates to a method for preparing rice noodles, in particular to a method for preparing digestion-resistant dry rice noodles. Background Art

[0002] Dry rice noodles are a traditional specialty food in southern my country. They are made from rice as the main raw material, with or without exogenous edible starch added, and are processed through processes such as washing, soaking, refining (crushing), maturation, molding, aging, and drying. The raw materials and processes of dry rice noodles in different places are generally not much different. They all use rice as the main raw material, with gelatinization (maturing), aging, and drying as the key processes. The process of dry rice noodles in Jiangxi is more complicated, with re-steaming and secondary aging. Taking the production process of Liuzhou snail rice noodles as an example, its process flow chart is as follows Figure 1 shown.

[0003] Liuzhou snail rice noodles are made of dry rice noodles with rice as the main raw material. They are rich in starch. After starchy foods are eaten, they are quickly metabolized into glucose in the human body, causing a blood sugar response in the human body and converting into energy required by the human body. Therefore, eating starchy foods is usually not friendly to people with chronic diseases such as hyperglycemia, diabetes, and obesity. Research on resistant starch and its nutritional functions that reduce the energy supply of starchy foods and slow down the rapid response of postprandial blood sugar has become an important topic in the research and development of staple foods. Dry rice noodles are rich in starch, and its content generally reaches more than 75%. Compared with fresh wet rice noodles, dry rice noodles undergo an aging process. Its essence is the process in which gelatinized starch gel tends to rearrange from disordered molecular chains to orderly ones, and a small amount of aged resistant starch (third type of resistant starch) is formed after aging. Because the starch aging time is short during the processing of dry rice noodles, it is short-term aging, and the rice protein in the rice raw material will also inhibit starch aging, and the content of resistant starch formed is low. The role of resistant starch in the diet is limited. For people with high blood sugar and energy control, the digestibility of dry rice noodles still needs to be improved. Summary of the invention

[0004] The technical problem to be solved by the present invention is: to provide a preparation method of digestion-resistant dry rice noodles. In the method, edible lipids are added during the processing process. On the one hand, the addition of lipids and toughening treatment can promote the combination of lipids and amylose, help to form starch-lipid complex type resistant starch, and improve the digestion resistance of the dry rice noodles. On the other hand, the addition of lipids regulates the aging of the dry rice noodles and can shorten the rehydration time of the dry rice noodles.

[0005] The technical solution to solve the above technical problem is: a method for preparing digestion-resistant dry rice noodles, comprising the following steps: (1) Raw material pretreatment: After washing the rice, soak it in water at room temperature for 8-12 hours, with the amount of water being 60-70% of the weight of the rice. Grind the rice into pulp and sieve it, and take the rice pulp under the sieve for later use; (2) Mixing and stirring the raw materials: adding edible corn starch in an amount of 20-30% by weight of rice to the rice slurry, and adding edible lipid in an amount of 1-5% by weight of rice and corn starch, and stirring and mixing thoroughly; (3) Toughening: The mixture is heated with stirring at 45-50°C for 15-25 minutes; (4) Gelatinization and extrusion molding: The toughened mixed slurry is added to an extruder at a temperature of 80-120°C. After the mixed slurry is fully gelatinized, it is extruded from the outlet and cut to obtain fresh wet rice noodles; (5) Aging: Aging fresh wet rice noodles at 25-40°C for 6-8h; (6) Drying: The aged rice noodles are dried at 30-40°C to obtain dry rice noodles.

[0006] Furthermore, in step (2), the edible lipid is edible oil, oleic acid, linoleic acid or lauric acid.

[0007] Furthermore, in step (1), the rice is indica rice.

[0008] Furthermore, in step (1), the slurry is ground and crushed through a 80-100 mesh sieve.

[0009] Starch and lipids compound under certain conditions to form starch-lipid complex, which is the fifth type of resistant starch. Adding a small amount of lipid components during the processing of dry rice noodles can increase the content of resistant starch, thereby improving the digestibility of dry rice noodles, which is of great significance for reducing the energy supply of dry rice noodles and slowing down the rapid response of blood sugar after meals.

[0010] The present invention processes rice and water into a water-solid mixed system, which is incompatible with lipids. Therefore, the addition of lipids requires a certain degree of change in the current production technology of dry rice noodles. The purpose of adding lipids is: (1) lipids form a complex with starch during toughening, gelatinization, aging, and drying to form resistant starch, thereby increasing the digestibility of dry rice noodles; (2) lipids regulate the aging of rice noodles and change the microstructure of rice noodles, thereby improving the quality of rice noodles, which is mainly reflected in the shortening of rehydration time.

[0011] Lipids can play two main roles in starch food systems: (1) Lipids form a complex with amylose, namely the fifth type of resistant starch (RS5), which has anti-digestive properties. The present invention intends to regulate the aging process of dry rice noodles by adding a small amount of edible lipid components (edible oils, oleic acid, linoleic acid or lauric acid) to rice noodles, thereby improving the quality and digestive resistance of dry rice noodles. (2) Inhibit and delay the aging of starch: lipids have a large number of hydroxyl groups, hydrophobic groups, and hydrophilic groups. The addition of lipids destroys the interaction between starch chains and starch-water in gelatinized starch gels, delays the aging of dry rice noodles, slows down the migration of water and the interaction between starch chains, thereby slowing down the orderly rearrangement of gelatinized starch. Compared with no lipid addition, the microstructure of the dry rice noodles of the present invention presents more microporous structures, which is conducive to the rapid rehydration of dry rice noodles. On the other hand, the hydrophobic effect of a small amount of lipids hinders the rapid diffusion and migration of water, slowing down the rapid softening of dry rice noodles after rehydration.

[0012] Compared with the prior art, the dry rice noodles prepared by the invention have increased digestibility, and the resistant starch content is increased by about 8-15%. The rehydration time of the dry rice noodles can be shortened by 25-35%, and the rehydrated dry rice noodles have a chewy texture and moderate viscoelasticity, and can be kept for a long time without being soft and rotten. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 : Existing Liuzhou snail rice noodle processing process flow chart.

[0014] Figure 2 : The preparation method process flow chart of the digestion-resistant dry rice powder of the present invention.

[0015] Figure 3 : XRD patterns of dry rice flour prepared by adding different masses of lauric acid according to the method described in the embodiment of the present invention.

[0016] Figure 4 : XRD patterns of dry rice flour prepared by adding 5% lauric acid and using different aging times according to the method described in the embodiment of the present invention.

[0017] Figure 5 : Comparative Example and the dry rice powder photos prepared by Examples 1-3 of the present invention. In the figure, from left to right are the dry rice powder prepared by the comparative example, Example 1, Example 2, and Example 3, respectively. It can be seen from the figure that the addition of edible lipids has no effect on the morphology of the dry rice powder product, and does not affect the acceptability of consumers. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. 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 creative work are within the scope of protection of the present invention.

[0019] Embodiment 1-embodiment 12: After the indica rice is washed, 67% of the weight of the indica rice is added to the water and soaked for 10 hours at room temperature, the indica rice is ground and crushed through a 90-mesh sieve, and the rice slurry under the sieve is taken, and edible corn starch of 20% by weight of the rice is added to the rice slurry, and edible lipids are added at the same time, and the mixture is stirred and mixed uniformly. The mixture is stirred and heated at 48°C for 20min for toughening, so that the starch granule structure swells, the starch granule structure is slightly broken, and the lipids migrate to the inside of the starch granules; the mixed slurry treated with toughening is added to a screw extruder (a round hole mold is installed at the outlet), the temperature in the extruder is 100°C, and the mixed slurry is fully gelatinized and extruded from the outlet, and cut when it is of suitable length to obtain fresh wet rice noodles; the fresh wet rice noodles are aged at 40°C for 7h, and then dried at 35°C to obtain dry rice noodles.

[0021]

[0022] In the embodiment, the added amount of edible oil is calculated as a percentage of the weight of indica rice and corn starch.

[0023] The preparation method of the comparative example is basically the same as that of the example, except that no edible lipid is added. The resistant starch content of the dry rice flour prepared in the comparative example and the example is shown in Table 2, and the rehydration time is shown in Table 3.

[0024]

[0025] Through XRD analysis, when the amount of lauric acid added exceeds 5%, Figure 3 As shown in the figure, a small diffraction peak appeared at 21.6° in 2θ. The intensity of the diffraction peak increased with the increase of lipid content. The diffraction peak at this location was found to be residual free fatty acids by comparison with the lipid diffraction peak. After alcohol elution, the diffraction peak of 2θ at 21.6° disappeared or significantly decreased. Therefore, considering the negative effects of residual free fatty acids and alcohol elution in rice flour, the amount of lipid added should not exceed 5%.

[0026] To study the effect of lipid addition on the aging process of rice noodles, Figure 4As shown in the figure, 2θ has obvious diffraction peaks near 13° and 20°, which are characteristic peaks of the complex, indicating that starch-lipid complexes have occurred in rice flour. As the aging time increases, 2θ has a gradually increasing diffraction peak at 17.5°, which is a characteristic peak of starch aging and orderly rearrangement. This shows that both starch-lipid complexes and starch aging rearrangements have occurred in rice flour, and RS3 and RS5 are formed in the system at the same time. Therefore, the resistant starch content in Table 2 is actually the sum of the contents of RS3 and RS5 resistant starches.

[0027] As can be seen from Table 2, the resistant starch content of dry rice noodles with added edible lipids is higher than that without added edible lipids, and the more edible lipids are added, the more resistant starch content the dry rice noodles have. The higher the resistant starch content, the higher the digestibility of the dry rice noodles, and the more friendly they are to people with chronic diseases such as hyperglycemia, diabetes, and obesity.

[0028]

[0029] As can be seen from Table 3, the rehydration time of dry rice noodles with added edible lipids is shorter than that without added edible lipids, and the more edible lipids are added, the more the rehydration time is shortened. The shorter the rehydration time, the better the quality of the dry rice noodles.

Claims

1. A method for preparing digestion-resistant dry rice flour, characterized in that: The following steps are involved: (1) Raw material pretreatment: After washing the rice, soak it in water at room temperature for 8-12 hours, with the amount of water being 60-70% of the weight of the rice. Grind the rice into pulp and sieve it, and take the rice pulp under the sieve for later use; (2) Mixing and stirring the raw materials: adding edible corn starch in an amount of 20-30% by weight of rice to the rice slurry, and adding edible lipid in an amount of 1-5% by weight of rice and corn starch, and stirring and mixing thoroughly; (3) Toughening: The mixture is heated with stirring at 45-50°C for 15-25 minutes; (4) Gelatinization and extrusion molding: The toughened mixed slurry is added to an extruder at a temperature of 80-120°C. After the mixed slurry is fully gelatinized, it is extruded from the outlet and cut to obtain fresh wet rice noodles; (5) Aging: Aging fresh wet rice noodles at 25-40°C for 6-8h; (6) Drying: The aged rice noodles are dried at 30-40°C to obtain dry rice noodles.

2. The method for preparing a digestion-resistant dry rice flour according to claim 1, wherein: In step (2), the edible lipid is edible oil, oleic acid, linoleic acid or lauric acid.

3. The method for preparing a digestion-resistant dry rice flour according to claim 1 or 2, wherein: In step (1), the rice is indica rice.

4. The method for preparing a digestion-resistant dry rice flour according to claim 1 or 2, wherein: In step (1), the slurry is ground and crushed through a 80-100 mesh sieve.

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