Making process of rice flour dumpling wrappers

Abstract

The present invention provides a rice flour dumpling wrapper production process, which comprises: weighing rice, adding distilled water, soaking for 30 min under 0.1 Mpa vacuum, drying the rice at 70 DEG C until the water content is about 14%, crushing by using a cyclone mill, and screening to obtain soaked dry milled powder; xanthan gum or guar gum accounting for 2.0% of the mass of the rice flour is added, and water accounting for two times of the mass of the rice flour is mixed and added; and fermenting at room temperature for 15 minutes, and preparing the dumpling wrappers according to a conventional method. According to the method, the rice flour is prepared by soaking and dry grinding, hydrophilic colloid is added in the flour making process, and the gluten-free rice dumpling wrapper which is good in appearance, appearance, taste and the like is obtained by optimizing the flour making process. According to the method, the cooking loss rate of the dumpling wrappers is reduced, and the cooking characteristics of the rice dumpling wrappers are improved.

Description

Technical Field

[0001] The invention relates to a production process of rice flour dumpling wrappers and belongs to the technical field of rice flour improvement. Background Art

[0002] Dumplings are a traditional food in my country and are loved by consumers. Traditional dumpling wrappers are made from wheat flour, which is not friendly to people with gluten intolerance. Rice does not contain gluten protein and is the first choice for gluten-free food materials. Rice is rich in nutrients, tastes good, and is easy to digest and absorb. However, in the process of making dumpling wrappers from rice, there are difficulties in shaping, the product is not chewy enough after cooking, and it is easy to disperse and crack in the soup, causing the soup to be mixed. Therefore, the quality improvement of gluten-free dumpling wrappers is a research hotspot in this field.

[0003] Hydrophilic colloids contain a large number of hydrophilic groups and have good water absorption and water holding capacity. They can change the distribution of water molecules, improve the gelatinization, rheology and gel properties of rice, and thus improve the quality of rice products. Therefore, by adding hydrophilic colloids, the effect of hydrophilic colloids on dumpling wrappers was further evaluated through color, cooking properties, texture properties and sensory evaluation, and the effect of hydrophilic colloids on the quality and sensory properties of dumpling wrappers was studied. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a process for making rice flour dumpling wrappers.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A process for making rice flour dumpling wrappers, the method comprising the following steps:

[0007] (1) Preparation of soaked dry-ground powder: weigh 80 g of rice, add 120 g of distilled water, soak for 30 min to 60 min under a vacuum of 0.03 MPa to 0.1 MPa, then dry the rice at 40° C. to 100° C., grind with a low-temperature continuous hammer cyclone mill, pass through an 80-mesh sieve, and put into a ziplock bag for standby use;

[0008] (2) adding xanthan gum or guar gum in a ratio of 0.5% to 2.0% by mass of rice flour, mixing with the rice flour, adding water, and mixing the mixture on a magnetic stirrer for 30 minutes to prepare a dough, covering the dough with plastic wrap, and proofing the dough at room temperature for 15 minutes, and making dumpling wrappers according to a conventional method.

[0009] Preferably, a vacuum impregnation machine is used at a vacuum degree of 0.1 MPa for immersion for 30 minutes, and then drying is performed at 70°C.

[0010] Preferably, xanthan gum or guar gum is added in a ratio of 1.0% by mass of the rice flour.

[0011] Beneficial effects of the present invention:

[0012] (1) The present invention adopts soaking and dry grinding to prepare rice flour, adds hydrophilic colloid in the flour making process, and obtains gluten-free rice dumpling wrappers with good appearance, appearance, taste, etc. by optimizing the flour making process.

[0013] (1) The present invention optimizes the soaking and dry-milling process, takes the damaged starch content of rice flour as the optimization index, and adopts orthogonal test to obtain the optimal process parameters of the soaking and dry-milling method: the vacuum degree is 0.1 MPa, the soaking time is 30 min, and the drying temperature is 70° C. The damaged starch content of the rice flour prepared by this process is 5.10%.

[0014] (2) The present invention adds hydrophilic colloids, prolongs the optimal cooking time of rice dumpling wrappers, increases the water absorption rate of the dumpling wrappers, reduces the cooking loss rate of the dumpling wrappers, and improves the cooking characteristics of the rice dumpling wrappers.

[0015] (3) The experiment showed that as the amount of hydrophilic colloid added increased, the scores of the dumpling skin's appearance, surface, taste and soup turbidity increased, but the appearance of the dumpling skin changed slightly; when the amount of hydrophilic colloid added was too much, the taste score of the dumpling skin decreased. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The damaged starch content of rice flour prepared by different milling processes;

[0017] Figure 2 Particle size distribution of rice flour prepared by different milling processes;

[0018] Figure 3 The effect of hydrocolloid on the cooking time of dumpling wrappers;

[0019] Figure 4 Effect of hydrocolloids on the cooking properties of dumpling wrappers;

[0020] Figure 5 Effect of hydrophilic colloid on shear hardness of dumpling wrapper;

[0021] Figure 6 Effect of hydrocolloids on the overall sensory score of dumpling wrappers. DETAILED DESCRIPTION

[0022] The specific implementation methods of the present invention are further described in detail below in conjunction with the examples. Unless otherwise specified, the instruments and equipment involved are all conventional instruments and equipment, the reagents involved are all commercially available conventional reagents, and the test methods involved are all conventional methods.

[0023] Embodiment 1 A kind of preparation technology of rice flour dumpling wrapper

[0024] The method specifically comprises the following steps:

[0025] (1) Preparation of soaked dry-ground powder: Weigh 80 g of indica rice, add 120 g of distilled water, use a vacuum impregnation machine to soak for 30 min under a vacuum degree of 0.1 MPa, then dry the rice at 70° C. to reduce the moisture content to about 14%, then use a low-temperature continuous hammer cyclone mill to crush and sieve (80 mesh), put it into a ziplock bag and store it at 4° C. for use.

[0026] (2) Mix xanthan gum or guar gum with rice flour in a ratio of 2.0% by weight of the rice flour, and add water so that the ratio of rice flour to water is 1:2 (w / w).

[0027] (3) Stirring on a magnetic stirrer for 30 min to prepare dough, covering with plastic wrap, and proofing at room temperature for 15 min, and making dumpling wrappers according to conventional methods.

[0028] Example 2 Process Optimization of Soaking Dry Grinding

[0029] Taking different vacuum degrees (0.1Mpa, 0.03Mpa, 0.06Mpa), different soaking times (30min, 45min, 60min), and different drying temperatures (40℃, 70℃, 100℃) as the investigation factors, and the damaged starch content as the main investigation index, the L9(3 3 ) Orthogonal test, according to the process of Example 1, determine the best process conditions for soaking dry grinding.

[0030] Table 1 Orthogonal experimental results of soaking dry grinding process parameters

[0031]

[0032] It can be seen from the test results that, with damaged starch content as the evaluation index, the influence of various factors on the damaged starch content is C>A>B, that is, the drying temperature has the greatest influence on the degree of starch damage, followed by the vacuum degree, and finally the soaking time. The best process conditions determined are A1B1C2, that is, the vacuum degree is 0.1Mpa (normal pressure), the soaking time is 30min, and the drying temperature is 70°C. The process conditions were verified and the damaged starch content was 5.10%.

[0033] Example 3 Comparison of different milling processes

[0034] Dry-grinded powder: Take 80g of rice, use a low-temperature continuous hammer cyclone mill to grind and sieve (80 mesh), put it into a ziplock bag, and store it at 4℃ for later use.

[0035] Wet-grinded powder: weigh 80g rice, add 120g distilled water, soak at 4℃ for 24h, and grind into rice slurry with colloid mill. Filter the rice slurry, dry the filter cake in a 40℃ constant temperature forced air drying oven, grind through an 80-mesh sieve, put into a ziplock bag, and store at 4℃ for later use.

[0036] Soaked dry milled powder: Soaked dry milled powder was prepared according to the optimal process conditions of Example 2, 80 g of rice was weighed and added with 120 g of distilled water, and the mixture was soaked for 30 min at a vacuum degree of 0.1 MPa using a vacuum impregnator, and then the rice moisture was dried to about 14% at a temperature of 70°C, and the mixture was crushed and sieved (80 mesh) using a low-temperature continuous hammer cyclone mill, and then put into a ziplock bag and stored at 4°C for use.

[0037] 3.1 Effect of different milling processes on the damaged starch content of rice flour

[0038] During the milling process, grains are subjected to mechanical effects such as friction, shearing, and extrusion, which destroys the intact starch granule structure and forms damaged starch. This change reduces the starch's resistance to enzymatic hydrolysis. Damaged starch and particle size distribution are two key factors affecting the physical and chemical properties and applications of rice flour.

[0039] Depend on Figure 1 It can be seen that there are significant differences in the damaged starch content of rice flour with different milling processes (p<0.05), among which the damaged starch content of wet-milled flour is the smallest, with a value of 1.07%. During the soaking of rice before wet milling, the hardness of rice grains will decrease. Due to the exudation of proteins, lipids and minerals and the entry of water, the endosperm structure becomes fragile. In addition, a large amount of water absorbs the heat energy generated by milling during wet milling, thereby reducing the damage to starch. Therefore, the damaged starch content in wet milled flour is the lowest, and the starch structure is relatively complete. The damaged starch content of dry milled flour is the highest (6.10%), which is about 6 times that of wet milled flour. The mechanical force and heat of the dry milling process cause the damaged starch content of dry milled flour to be the highest. The damaged starch content of soaked dry milled flour is between dry milled flour and wet milled flour, indicating that the soaking and drying treatment in the early stage of soaked dry milled flour makes the rice texture crispy, weakens the mechanical damage of the milling instrument to the indica rice grains, and reduces the damaged starch content of rice flour.

[0040] Figure 1 Different letters above the bar graphs represent significant differences among samples (P<0.05).

[0041] 3.2 Effect of different milling processes on rice flour particle size distribution

[0042] The particle sizes of rice flours produced by different milling processes are shown in Table 2. D10, D50, and D90 represent the fine end particle size, average particle size, and coarse end particle size of the powder, respectively. It can be seen that there are significant differences in the average particle size and fine end particle size of rice flours produced by different milling processes (p<0.05). The average particle size of dry-milled powder is 85.13 μm, which is much larger than the average particle size of wet-milled powder (43.77 μm). This is mainly because water molecules gradually penetrate from the surface of the particles to the inside during the soaking process, resulting in a loose structure and easier breakage, resulting in a smaller particle size.

[0043] Figure 2 The results show that wet-milled flour has the finest average particle size and the smallest particle size range. Wet-milled flour is mainly composed of two types of particles with particle sizes of 2-20 μm and 20-200 μm, respectively. In addition, compared with dry-milled flour and soaked dry-milled flour, the particle size distribution shows that the volume fraction of fine particles in wet-milled flour increases. Compared with dry-milled flour, soaked dry-milled flour reduces the average particle size of the particles, but increases the fine end particle size of the particles. This may be because the structure of rice grains after soaking is looser than that of unsoaked rice grains, and cracks are produced in rice after drying, which is easy to crush. In addition, the equipment for both processes is a hammer cyclone mill, which relies on wind power to blow out rice flour. During the milling process, soaked dry-milled rice grains are easy to crush, and the milling time of rice grains in the mill is relatively short. Therefore, the average particle size of soaked dry-milled flour is smaller than that of dry-milled flour, and the fine end particle size is larger than that of dry-milled flour.

[0044] Table 2 Particle size of rice flour prepared by different milling processes

[0045]

[0046] 3.3 Effects of different milling processes on the gelatinization properties of rice flour

[0047] The effects of different milling processes on the gelatinization properties of rice flour are shown in Table 3. The peak viscosity of dry-milled flour is significantly lower than that of wet-milled flour and soaked dry-milled flour (p<0.05). The lower peak viscosity is caused by the higher damaged starch content of dry-milled flour. The peak viscosity of wet-milled flour and soaked dry-milled flour is higher, which is closely related to the stacking structure of gelatinized starch granules. Dry-milled flour shows a lower regeneration value than wet-milled flour and soaked dry-milled flour. There are more damaged starch granules in dry milling, and the ability to rearrange associated crystals during the regeneration process is relatively weak. The regeneration value is small and the degree of starch aging is low, indicating that the degree of recrystallization between starches in dry-milled flour is low during cooling. The gelatinization temperature refers to the temperature at which the viscosity of the sample just begins to increase and the sample begins to gelatinize, indicating the minimum temperature required for cooking the sample. The energy required for the gelatinization process of intact starch granules is more than that required for damaged starch, that is, gelatinization requires a higher temperature. The damaged starch content in wet-milled flour is less, so its gelatinization temperature is higher than that of dry-milled flour and soaked dry-milled flour.

[0048] Table 3 Gelatinization characteristics of rice flour prepared by different milling processes

[0049]

[0050] Example 4 Effect of hydrophilic colloids on rice flour quality characteristics

[0051] Hydrophilic colloids contain a large number of hydrophilic groups and have good water absorption and water retention capabilities. They can change the distribution of water molecules, improve the gelatinization, rheology and gel properties of rice, and thus improve the quality of rice products.

[0052] Rice flour was prepared by the soaking and dry grinding method of Example 3, and then compounded with xanthan gum (XG) or guar gum (GG) to explore the effects of xanthan gum and guar gum on the physicochemical properties of rice flour and to reveal the effects of different added amounts of hydrophilic colloids on the properties of rice flour.

[0053] 4.1 Effect of hydrocolloids on the optimal cooking time of dumpling wrappers

[0054] Effect of hydrocolloids on the optimal cooking time of dumpling wrappers Figure 3 As shown in the figure, with the increase of the amount of hydrophilic colloid added, the cooking time of the dumpling skin increases continuously. This may be because the hydrophilic colloid has a strong hydration effect and can interact with starch, hindering and inhibiting the water absorption and expansion of starch, thus prolonging the cooking time. In addition, during the cooking process, the hydrophilic colloid forms a gel with a certain viscosity in the dumpling skin, which hinders heat transfer. In addition, guar gum has a stronger effect on extending the cooking time of dumpling skin than xanthan gum.

[0055] 4.2 Effect of hydrocolloids on the cooking properties of dumpling wrappers

[0056] The cooking properties can be determined by the cooking loss rate and water absorption rate. Figure 4 As shown. The cooking loss rate is the ratio of the total amount of solids remaining in the water after cooking to the total mass of the dumpling skin. With the increase of the amount of hydrophilic colloid added, the cooking loss rate of the dumpling skin decreased significantly (p<0.05). This may be because during the cooking process, the hydrophilic colloid absorbs water and expands to form a three-dimensional structure, which enhances the binding force of the hydrophilic colloid on starch granules, especially damaged starch, making it difficult for starch granules and soluble proteins to be freed from the dumpling skin, reducing the residual solid content in the soup after cooking. The results show that hydrophilic colloid significantly (p<0.05) increases the water absorption rate of the dumpling skin. This is because the hydrophilic colloid itself has a certain water holding capacity. During the cooking process, the hydrophilic colloid competes with the starch granules for water to form a gel. It can be seen that hydrophilic colloid improves the cooking characteristics of the dumpling skin, and the improvement effect of xanthan gum is better than that of guar gum.

[0057] 4.3 Effect of hydrophilic colloid on shear hardness of dumpling wrappers

[0058] Shear hardness is one of the important indicators to characterize the quality of dumpling wrappers. It can objectively reflect the texture of dumpling wrappers and has an important influence on the taste and edible quality of dumpling wrappers. Figure 5As shown in the figure. After adding hydrophilic colloid, the shear hardness of dumpling wrapper increases, and is positively correlated with the amount of hydrophilic colloid added. On the one hand, it may be because the hydrophilic colloid is distributed in the pores between rice starch particles, making the internal structure of the dumpling wrapper dense and compact; on the other hand, the hydrophilic colloid has a strong water binding ability and can form a strong structure in the dumpling wrapper. During cooking, the hydrophilic colloid can form a highly viscous tissue structure, which increases the shear hardness of the dumpling wrapper.

[0059] 4.4 Effect of hydrocolloids on sensory evaluation of dumpling wrappers

[0060] Sensory evaluation is the most direct and commonly used method to evaluate the edible quality of food.

[0061] Table 4 shows the sensory scores of dumpling wrappers with different hydrophilic colloid additions. As shown in Table 4, with the increase of xanthan gum addition, the appearance, aroma, taste and soup turbidity of dumpling wrappers are improved, but when the xanthan gum addition is 1.5% to 2.0%, the taste of dumpling wrappers is significantly reduced, which may be related to the high hardness of dumpling wrappers. Xanthan gum is adsorbed and wrapped on the surface of rice starch and distributed in the pores of rice starch, making the dumpling wrapper structure tight and the hardness increased. Xanthan gum significantly improves the appearance, aroma and soup turbidity of dumpling wrappers. This may be due to the fact that during the dough mixing process, xanthan gum has strong water holding capacity and enhances the interaction between starches. Under the same process, the quality of dumpling wrappers increases, and it contains more rice flour, thereby increasing the rice aroma of dumpling wrappers. During the cooking process, hydrophilic colloids absorb water to form a solid three-dimensional structure, which hinders the absorption and expansion of starch and the precipitation of some water-soluble substances in dumpling wrappers, thereby improving the appearance and soup turbidity. The effects of guar gum on the appearance, taste and turbidity of dumpling wrappers are the same as those of xanthan gum, but the aroma decreases with the increase of guar gum addition, showing a negative correlation.

[0062] The total sensory scores of rice dumpling wrappers with different hydrocolloid addition amounts are as follows Figure 6 As shown by Figure 6 It can be seen that the total sensory score of dumpling wrappers increases first and then decreases with the increase of hydrophilic colloid addition. This result shows that an appropriate amount of hydrophilic colloid can improve the sensory quality of rice dumpling wrappers, but excessive hydrophilic colloid makes the dumpling wrappers too hard, thereby reducing the total score of the dumpling wrappers. Guar gum has a peculiar smell. At the same addition amount, the total score of guar gum dumpling wrappers is lower than that of xanthan gum.

[0063] Table 4 Effect of hydrocolloid on sensory score of dumpling wrapper

[0064]

Claims

1. A process for making rice flour dumpling wrappers, characterized in that: The method comprises the following steps: (1) Preparation of soaked dry-ground powder: weigh 80 g of rice, add 120 g of distilled water, soak for 30 min to 60 min under a vacuum of 0.03 MPa to 0.1 MPa, then dry the rice at 40° C. to 100° C., grind with a low-temperature continuous hammer cyclone mill, pass through an 80-mesh sieve, and put into a ziplock bag for standby use; (2) adding xanthan gum or guar gum in a ratio of 0.5% to 2.0% by mass of the rice flour, mixing the mixture evenly with the rice flour, adding water, and adding water in a ratio of 1:2 by mass of the rice flour to the water; stirring the mixture magnetically for 30 minutes to prepare a dough, proofing the dough at room temperature for 15 minutes to 30 minutes, and making dumpling wrappers according to a conventional method.

2. The manufacturing process according to claim 1, characterized in that: A vacuum impregnation machine was used for impregnation with a vacuum degree of 0.1 MPa, the mixture was immersed for 30 minutes, and then dried at 70°C.

3. The manufacturing process according to claim 1, characterized in that: Add xanthan gum or guar gum at a ratio of 1.0% by mass of rice flour.

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