Emulsified oil for preparing semi-dried rice noodles and method for preparing semi-dried rice noodles

Abstract

The present application belongs to the technical field of semi-dry rice noodle products, and relates to emulsified oil for preparing semi-dry rice noodles and a preparation method of semi-dry rice noodles. The semi-dry rice noodles are prepared by weighing, stirring, aging, extruding, passing through a steaming box, spraying the emulsified oil, cooling, shearing and freezing the loose noodles. After the emulsified oil of the present application is sprayed and the loose noodles are then frozen, the loose noodle rate is greatly improved, and the freezing time of the loose noodles is shortened. The semi-dry rice noodles prepared by the present application retain the characteristics of traditional rice noodles, and at the same time, the product has the characteristics of being convenient to eat and resistant to storage. The semi-dry rice noodles have a smooth surface, are not prone to breaking, have a low slurry rate, have a smooth taste, and the eating method of the semi-dry rice noodles is both brewing and cooking. Both of the two eating methods can achieve eating while ensuring the toughness, elasticity, smoothness and other tastes of the rice noodles. In addition, whether for cooking or brewing, the semi-dry rice noodles are not prone to breaking and are not prone to being pasty.

Description

Technical Field

[0001] This invention belongs to the technical field of semi-dried rice noodle products, and relates to an emulsified oil for preparing semi-dried rice noodles and a method for preparing semi-dried rice noodles. Background Technology

[0002] Rice noodles (also known as rice vermicelli, rice strands, or rice noodles) are a traditional food with a long history in my country. They can be eaten as a staple food or as a snack and are a common rice product consumed by people in several southern provinces. Rice noodles are generally made from fresh rice, and are produced through more than ten processes, including impurity removal, washing, soaking, grinding, gelatinization, shaping, cooling, and loosening. There are many varieties of rice noodles. According to different classification methods, they can be divided into the following categories: (1) The basic shape of the product is different depending on the forming technology in the production process of rice noodles: Rice noodles are divided into pressed rice noodles and cut rice noodles according to the different product shapes; pressed rice noodles, that is, straight rice noodles, can be thick, medium, thin, etc. due to different local eating habits. By adjusting the pressure and extrusion speed of the extruder, wavy rice noodles can also be obtained; while steaming and cutting rice noodles result in cut rice noodles. Cut rice noodles have a certain width and thickness. Due to different local eating habits, they can be medium wide or thin wide; (2) Rice noodles are divided into ordinary rice noodles, refined dry rice noodles, semi-dry rice noodles, and fresh wet rice noodles according to the different processing methods before consumption. Semi-dry rice noodles mainly refer to rice noodles with a moisture content of 35%-50%. The production process is generally the same as that of fresh wet rice noodles, but they are more resistant to storage and more resilient than fresh wet rice noodles. The convenience rice noodle industry is just getting started, but there are still many shortcomings compared to traditional rice noodles: semi-dried rice noodles have disadvantages such as long rehydration time and difficulty in absorbing flavor; compared to traditional rice noodles, they are either too hard or too soft, not smooth enough, and have a higher viscosity.

[0003] Currently, there are relatively few semi-dried rice noodle products available. Most semi-dried rice noodle manufacturers have high production costs, poor taste, low production line efficiency, and the noodles tend to clump together when brewed. Furthermore, they have a short shelf life, significant changes in taste within the shelf life, and are prone to aging and reversion. The loosening stage in the preparation of semi-dried rice noodles typically involves washing them with water to prevent sticking. However, this method often fails to remove the powdery substances from the surface of the noodles, leading to a cloudy or mushy broth during cooking. Currently, there is a lack of a simple and effective loosening method to solve this problem. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an emulsified oil for preparing semi-dried rice noodles and a method for preparing semi-dried rice noodles. By controlling the proportion of raw materials to achieve the best taste, and by improving the stable temperature and time during the maturation stage, the problem of insufficient or excessive aging is solved. A freezing and loosening process improves the stability of the rice noodles' taste during storage, giving the product the advantage of being both brewed and cooked, while also saving freezing time and costs. Compared to semi-dried rice noodles on the market, the semi-dried rice noodles of this invention have a series of advantages, including being more resistant to soaking and cooking, smoother, more resilient, not becoming mushy in soup, not breaking, and having better storage properties.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0006] On one hand, the present invention provides an emulsified oil for preparing semi-dried rice noodles, comprising the following raw materials by mass percentage:

[0007] 25%-40% phospholipids, 35-40% palm oil, 10%-15% glycerol fatty acid esters, with the balance being soybean oil.

[0008] In the above-mentioned application of emulsified oil for preparing semi-dried rice noodles, the emulsified oil with a concentration of 2% is sprayed onto the rice noodles and then frozen and fed into the noodles. The weight ratio of emulsified oil to rice noodles is 400:1.

[0009] On the other hand, the present invention provides a method for preparing semi-dried rice noodles, comprising the following preparation steps:

[0010] S1. Weighing: Weigh rice flour, corn starch and potato starch according to a weight ratio of (40-45):(5-7.5):(2.5-5); wherein the rice flour has a protein content of 6%-8%, a fat content of 1.7%-2.2%, a soluble sugar content of 0.3%-0.6%, and a straight-chain starch content of 18%-25%;

[0011] S2. Stirring: Mix the rice flour, corn starch, potato starch and water from step S1 to obtain a slurry;

[0012] S3. Mashing: The slurry obtained in step S2 is fed into the gelatinizer at a uniform speed of 50 mL / s. The steam valve is opened and the pressure of the gelatinizer is adjusted to 0.050 MPa-0.065 MPa. The internal gelatinization temperature is raised to 95℃-110℃ by steam pressurization and heating. At the same time, the gelatinization temperature and pressure of the gelatinizer are kept stable. The total gelatinization time from the material entering from the inlet to the material exiting from the outlet is 2 min-3 min.

[0013] S4. Extrusion: The gelatinized material in step S3 is extruded into rice noodles through the extrusion cylinder of the extruder.

[0014] S5. Steaming box: Place the rice noodles extruded in step S4 onto the conveyor belt and steam them.

[0015] S6. Spraying emulsified oil: After step S5, the rice noodles are sprayed with 2% concentration of the emulsified oil as described in claim 1. The weight ratio of rice noodles to emulsified oil is 400:1, so that a thin oil film is formed on the surface of the rice noodles, and no obvious oil is visible to the naked eye.

[0016] S7. Cooling: Turn on the fan to dry the surface moisture of the rice noodles;

[0017] S8. Cutting and Packaging: The rice noodles on the conveyor belt are neatly cut into strips of the required length by an automatic cutter, and then packaged with an oxygen absorber.

[0018] S9. Freezing and loosening: Freeze the rice noodles packaged in step S8 at -18℃ to -20℃ for 3 hours, and then thaw naturally to obtain semi-dried rice noodles.

[0019] Preferably, in step S2, the total weight ratio of rice flour, corn starch, and potato starch to the weight ratio of water is 1:1.

[0020] Preferably, in step S2, edible flavoring is added before stirring, and the amount of edible flavoring added is 0.1% of the total weight of rice flour, corn starch, potato starch and water; the stirring is: first stirring at a frequency of 15Hz for 10-15 minutes, and then stirring further at a frequency of 25Hz for 5 minutes.

[0021] Preferably, in step S3, the frequency of the curing machine is adjusted to 35Hz, that is, the twin screw speed of the curing machine is 220r / min, and the blade spacing between the threads is 20.0mm.

[0022] Preferably, in step S4, the feed inlet of the extruder is closely connected to the discharge outlet of the curing machine in step S3.

[0023] Preferably, in step S4, the extrusion cylinder of the extruder uses two end diversion baffles to make the gelatinized material be extruded into rice noodles at a uniform speed through the extruder. The diversion baffle is a diamond-shaped plate with a width of 80mm, a length of 600mm, a thickness of 12mm in the middle and 3mm on both sides. The diversion baffle has 8 small holes with a diameter of 10mm in the middle, and the spacing between each small hole is 20mm.

[0024] Preferably, in step S5, the steamer is divided into three sections of equal size, each with a different temperature: the first section has a temperature of 65-70℃, the second section has a temperature of 75-85℃, and the third section has a temperature of 70-80℃. The steaming time is 3 minutes.

[0025] Preferably, in step S7, the number of fans is 3 sets, and the air volume of each set of fans is 120m³. 3 / min.

[0026] The beneficial effects of this invention are:

[0027] 1. The emulsified oil raw material of the present invention is safe and non-toxic. By spraying the emulsified oil on the surface of rice noodles, the freezing and loosening efficiency of rice noodles can be improved, which not only improves the quality of semi-dried rice noodles, but also saves freezing and loosening time, saves costs, and greatly reduces the energy consumption of the loosening process.

[0028] 2. This invention uses rice flour with a soluble sugar content of 0.4%, along with corn starch and potato starch, as raw materials. Soluble sugar can inhibit starch aging. When rice flour contains soluble sugar, the resulting rice noodles can reduce retrogradation and breakage caused by aging by 10%. The fat (endogenous lipids) in rice flour can form a complex with amylose, delaying the transformation of starch structure and thus inhibiting rice flour aging, resulting in rice noodles with a good texture. The addition of corn starch and potato starch can improve the gel elasticity and chewiness of rice starch, and make its internal network structure most regular and dense, which is beneficial to improving the quality of rice noodles. It can effectively ensure that the rice noodles are resistant to boiling and do not break, increase their elasticity and toughness, and do not easily stick together after neutralization.

[0029] 3. In the maturation stage of this invention, the internal temperature of the maturation machine is maintained at 95℃-110℃ and the pressure at 0.050MPa-0.065MPa, which allows the slurry to be fully maturated in the maturation machine. The maturation machine and the extruder are integrated, which overcomes the problems of large equipment footprint and mismatch between the maturated material and the extruder caused by the separation of the maturation machine and the extruder. It also avoids the problem of inconsistent material flow when the maturated material enters the extruder, which would result in inconsistent thickness of the extruded rice noodles, or even breakage or material accumulation on the conveyor belt. By integrating the maturation machine and the extruder, the maturated material can enter the extruder immediately after maturation and be extruded into strands. The two are basically synchronized, and the extruded rice noodles are uniform and neat. Compared with traditional straight rice noodles, the uniformity and straightness of the rice noodle shape are significantly improved, while greatly saving equipment space.

[0030] 4. The extrusion stage of this invention uses a single extrusion cylinder. A specific pressure-dividing device (i.e., a flow-dividing baffle) is added to the center of the cylinder so that the pressure of the cooked material is divided to the periphery of the flow-dividing baffle after passing through the flow-dividing baffle, so that the material is evenly distributed in the extrusion cylinder and thus evenly extruded from the extrusion cylinder. This can ensure that each rice noodle is of uniform thickness, has a smooth surface, and is free of broken strips, thereby increasing the uniformity of the rice noodles and the stability of the product.

[0031] 5. The steaming stage of this invention employs a three-stage high-temperature steaming process to further cook the extruded rice noodles, increasing their flexibility and reducing the rate of mushy soup. In this stage, secondary steam is used to supplement the process load—the secondary steam generated from the condensate used for heating is used to supplement the heating load. High-pressure condensate is flash-evaporated to generate low-pressure steam, which is used to preheat the cold air in the steaming chamber. Since steam condensation may create a vacuum, a commercially available vacuum breaker is used to prevent negative pressure in the steam trap from causing condensate to flow back into the steam trap. The secondary steam is then dried using either direct heat exchange with the condensate or indirect heat exchange with the secondary steam. This utilization of secondary steam in the steaming chamber reduces overall steam consumption by 30%, saving costs.

[0032] 6. The semi-dried rice noodles of this invention do not contain any food preservatives, but instead contain 0.1% edible flavoring. This flavoring is added when the powder and water are mixed in the correct proportions and stirred together. The addition of edible flavoring ensures the stability of the product's taste and its own rice aroma, making the semi-dried rice noodles colorless, tasteless, and unchanged in taste. This maximizes the preservation of the product's authenticity while extending its shelf life. The semi-dried rice noodles produced by this method can meet the consumption standards within 7.2 months.

[0033] 7. In the loosening stage of this invention, the emulsified oil of this invention is added before loosening, and then the rice noodles are loosened using freezing technology. Loosening can be completed by freezing at -18°C for three hours. By spraying emulsified oil, an oil film can be formed between the rice noodle strands, thereby reducing surface viscosity. After freezing for three hours, the aging of the rice noodles is accelerated and stabilized, locking the moisture in the center of the rice noodle strands and further reducing the surface moisture, thereby achieving a loosening rate of 95%. This can shorten the freezing time by 65% ​​and basically does not increase the additional cost. At the same time, the effect is significant. After thawing, the semi-dried rice noodles are basically in a loose state, which also reduces some manual loosening. After being stored at room temperature for a period of time, the semi-dried rice noodles maintain a smooth texture, improving the taste of the semi-dried rice noodles.

[0034] 8. The semi-dried rice noodles prepared by the method of the present invention can be prepared by soaking or boiling. Both methods of consumption can ensure the toughness, elasticity, and smoothness of the rice noodles, while also preventing them from breaking or becoming mushy. Attached Figure Description

[0035] Figure 1 This is a diagram of rice noodles extruded according to Embodiment 1 of the present invention;

[0036] Figure 2 This is a schematic diagram of the gelatinizer and extruder of the present invention.

[0037] in, Figure 2 (a) is an integrated diagram of the gelatinizer and extruder of the present invention. Figure 2 (b) is a separate diagram of the gelatinizer and extruder;

[0038] Figure 3 This is a diagram of spraying emulsified oil in Embodiment 1 of the present invention;

[0039] Figure 4 is a comparison of the brewing effects of the semi-dried rice noodles of the present invention and commercially available rice noodles.

[0040] Among them, Figure 4(a) is a brewing diagram of semi-dried rice noodles in Embodiment 1 of the present invention, Figure 4(b) is a brewing diagram of fresh rice noodles from Guangxi Daoheguan Suo, Figure 4(c) is a cooking diagram of semi-dried rice noodles from Qujing Siwei, and Figure 4(d) is a cooking diagram of fresh wet rice noodles from Kunming Guanrenqiao.

[0041] Figure 5 This is a comparison diagram of the rice noodles in Embodiment 1 and Comparative Example 4 after opening the bag and not being subjected to force. Detailed Implementation

[0042] The principles and features of the present invention are described below (in conjunction with the accompanying drawings). The examples given are for illustrative purposes only and are not intended to limit the scope of the invention.

[0043] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0044] The sources of some of the raw materials for this invention are shown below:

[0045] The edible flavoring was purchased from Shenyang Renda Biotechnology Co., Ltd.; the chain-type 30 three-proof deoxidizer was purchased from Nanjing Weijiali Food Preservation Co., Ltd.

[0046] This invention provides an emulsified oil for preparing semi-dried rice noodles, comprising the following raw materials by mass percentage:

[0047] 25%-40% phospholipids, 35-40% palm oil, 10%-15% glycerol fatty acid esters, with the balance being soybean oil.

[0048] In the above-mentioned application of emulsified oil for preparing semi-dried rice noodles, the emulsified oil with a concentration of 2% is sprayed onto the rice noodles and then frozen and fed into the noodles. The weight ratio of emulsified oil to rice noodles is 400:1.

[0049] This invention also provides a method for preparing semi-dried rice noodles, comprising the following preparation steps:

[0050] S1. Weighing: Weigh rice flour, corn starch and potato starch according to a weight ratio of (40-45):(5-7.5):(2.5-5); wherein the rice flour has a protein content of 6%-8%, a fat content of 1.7%-2.2%, a soluble sugar content of 0.3%-0.6%, and a straight-chain starch content of 18%-25%;

[0051] S2. Stirring: Mix the rice flour, corn starch, potato starch and water from step S1 to obtain a slurry;

[0052] S3. Mashing (i.e. starch gelatinization): The starch slurry obtained in step S2 is fed into the gelatinizer at a uniform speed of 50 mL / s. The steam valve is opened and the pressure of the gelatinizer is adjusted to 0.050 MPa-0.065 MPa. The internal gelatinization temperature is raised to 95℃-110℃ by steam pressurization and heating. At the same time, the gelatinization temperature and pressure of the gelatinizer are kept stable. The total gelatinization time from the material entering from the inlet to the material exiting from the outlet is 2 min-3 min.

[0053] S4. Extrusion: The gelatinized material in step S3 is extruded into rice noodles through the extrusion cylinder of the extruder.

[0054] S5. Steaming box: Place the rice noodles extruded in step S4 onto the conveyor belt and steam them.

[0055] S6. Spraying emulsified oil: Spray the rice noodles with the above-mentioned emulsified oil at a concentration of 2%, with a weight ratio of rice noodles to emulsified oil of 400:1.

[0056] S7. Cooling: Turn on the fan to dry the surface moisture of the rice noodles so that they are soft and sticky when pressed with the palm of the hand, and do not stick to the conveyor belt when they are laid. At the same time, the surface of the rice noodles should not be too dry during the blowing process, which may cause the rice noodles to harden or break.

[0057] S8. Cutting and Packaging: The rice noodles on the conveyor belt are neatly cut into strips of the required length by an automatic cutter, and then packaged with an oxygen absorber.

[0058] S9. Freezing and loosening: Freeze the rice noodles packaged in step S8 at -18℃ to -20℃ for 3 hours, and then thaw naturally to obtain semi-dried rice noodles.

[0059] Preferably, in step S1, the rice flour is passed through a 100-mesh sieve, and the rice flour is Hunan rice flour.

[0060] Rice flour with a particle size of 100 mesh can reduce the cooking loss rate of rice noodles by about 10%; soluble sugars can inhibit starch retrogradation. When rice flour contains 0.4% soluble sugar, the rice noodles can reduce retrogradation and breakage caused by retrogradation by 10%; and rice flour fat (endogenous lipids) can form a complex with amylose, delaying the transformation of starch structure and thus inhibiting the retrogradation of rice flour.

[0061] In step S4, the extrusion cylinder has an extrusion orifice diameter of 1.8 mm, a total of 216 orifices, and an orifice spacing of 3.0 mm. The extruded rice noodles can be eaten by both soaking and cooking.

[0062] Of course, the orifice diameter of the extrusion cylinder can also be 2.2 mm, with a total of 175 orifices and a hole spacing of 3.0 mm; or it can be 1.5 mm, with a total of 230 orifices and a hole spacing of 3.0 mm.

[0063] In step S8, the deoxidizer is a chain-type 30 three-proof deoxidizer. The deoxidizer is waterproof, oilproof, and dustproof, and can completely absorb oxygen in the bag without affecting the quality of the rice noodles during the shelf life.

[0064] In step S9, the rice noodles are packaged first and then frozen to ensure the quality of the semi-dried rice noodles. When the packaged rice noodles are frozen, a small amount of water droplets will form on the inner wall of the packaging bag. Once the temperature returns to room temperature, the water droplets can be reabsorbed by the rice noodles, thus ensuring the quality of the rice noodles. If the rice noodles are frozen at -18℃ to -20℃ for 3-4 hours before packaging, on the one hand, the risk of microorganisms increases, which has a negative impact. On the other hand, freezing will cause the surface water of the rice noodles to sublimate and evaporate, causing the surface of the rice noodle cake to turn white. This results in a decrease in the moisture content of the rice noodles after freezing and repackaging, and the surface is prone to aging and regeneration. When brewed, the texture is hard, which affects the edibility.

[0065] Preferably, in step S4, the extruder frequency is adjusted to 30.00 Hz and the extrusion pressure is 0.65 MPa-0.75 MPa.

[0066] As an optional implementation, in step S2, the total weight ratio of rice flour, corn starch, and potato starch to the weight ratio of water is 1:1.

[0067] As an optional implementation, in step S2, edible flavoring is added before stirring, and the amount of edible flavoring added is 0.1% of the total weight of rice flour, corn starch, potato starch and water; the stirring is: first stirring at a frequency of 15Hz for 10-15 minutes, and then stirring further at a frequency of 25Hz for 5 minutes.

[0068] Specifically, the rice flour, corn starch, potato starch and water in step S1 are mixed, and then 0.1% of food flavoring is added. The mixture is first stirred at a frequency of 15Hz to make the materials basically mixed. When the stirring frequency is low, the materials are not easy to fly around. Then, the mixture is further stirred at a frequency of 25Hz to obtain a slurry. The slurry after high-speed stirring does not clump, and the material separates slowly when it is left to stand still.

[0069] As an optional implementation, in step S3, the frequency of the curing machine is adjusted to 35Hz, that is, the twin screw speed of the curing machine is 220r / min, and the blade spacing between the threads is 20.0mm.

[0070] This process ensures complete and uniform gelatinization of the slurry. Inside the curing drum, the powder is subjected to the squeezing, shearing, and friction of the screw, propelling it forward and generating significant heat. This heating softens the starch, causing a series of changes: the starch gelatinizes (α-gelatinization), transforming the rice flour into a flowable gel. Specifically, the curing auger is 100cm long, allowing for thorough curing of the material within the curing machine. The curing time from the inlet to the outlet is 2-3 minutes, ensuring a curing rate greater than 80%. The consistent temperature throughout the screw during curing ensures stable heating. Using a twin-screw extruder provides more thorough slurry mixing, better heat transfer, stronger venting capacity, and more stable temperature control compared to a single-screw extruder.

[0071] As an optional implementation, in step S4, the feed inlet of the extruder is tightly connected to the discharge outlet of the curing machine in step S3. Specifically, the curing machine and the extruder are arranged side by side, such as... Figure 2 As shown.

[0072] Figure 2 (a) is an integrated diagram of the gelatinizer and extruder of the present invention. Figure 2 (b) is a diagram showing the separation of the gelatinizer and extruder in the prior art. In this invention, the gelatinizer and extruder are arranged in parallel, and the gelatinizer and extruder can share a single motor. Their frequencies can be synchronized, so that the powder can immediately enter the extrusion stage after gelatinization. This avoids the situation where the material enters the extruder at different speeds after gelatinization, resulting in inconsistent thickness of the extruded rice noodles, or even breakage or material accumulation on the conveyor belt. By connecting the gelatinizer and extruder into one unit, the gelatinized material can immediately enter the extruder for extrusion. The frequencies of the two are basically synchronized, and the extruded rice noodles are uniform and neat. Compared with traditional straight rice noodles, the uniformity and straightness of the rice noodle shape are significantly improved, while greatly saving equipment space.

[0073] As an optional implementation, in step S4, the extrusion cylinder of the extruder uses two end diversion baffles to make the gelatinized material be extruded into rice noodles at a uniform speed through the extruder. The diversion baffle is a diamond-shaped plate with a width of 80mm, a length of 600mm, a thickness of 12mm in the middle and 3mm on both sides. The diversion baffle has 8 small holes with a diameter of 10mm in the middle, the 8 holes are evenly distributed, and the spacing between each small hole is 20mm.

[0074] The diversion baffle mainly functions at the center of the extrusion cylinder to ensure that each rice noodle is distinct, extruded evenly, and at a consistent speed, with a smooth surface and uniform thickness without breaks. If the diversion baffle has more than 8 holes, the rice noodles extruded from the extrusion cylinder will be thicker in the middle and thinner at the ends, while fewer than 8 holes will have the opposite effect. The 8 holes allow the material to be more evenly distributed among the 216 holes of the extrusion cylinder, ensuring that the rice noodles extruded from each hole are uniform and without breaks. If the diversion baffle is missing, the thickness of the extruded rice noodles will be uneven between each hole, and the surface will not be smooth enough, resulting in a spiral appearance.

[0075] As an optional implementation, in step S5, the steamer is divided into three equal sections, each with a different temperature: the first section is 65-70℃, the second section is 75-85℃, and the third section is 70-80℃. The steaming time is 3 minutes. Excessive temperature will lead to excessive steam loss, increasing costs, and will also cause excessive humidity inside the steamer, increasing the viscosity of the rice noodles. Insufficient temperature will result in incomplete gelatinization of the rice noodles, making them prone to whitening, aging, and reversion during storage, as well as causing a mushy soup and breakage during brewing.

[0076] By dividing the steamer into three sections with different temperature ranges for re-steaming the extruded rice noodles, the rice noodles are further cooked, while increasing their elasticity and reducing the rate of mushy soup when brewing.

[0077] Specifically, during the steaming stage, the steam discharged from the steaming box is used as secondary steam to assist in heating the steaming box. In other words, the secondary steam generated from the condensate used for heating is used to supplement the heating load. That is, the high-pressure condensate is flashed to generate low-pressure steam, which is used to preheat the cold air in the steaming box.

[0078] The flashover of steam condensate may cause a vacuum in the pipeline. Therefore, a vacuum breaker is used to prevent the pressure inside the steam trap from becoming negative and causing the condensate to flow back into the steam trap. Then, the condensate is used for direct heat exchange or secondary steam is used for indirect heat exchange to achieve resource recycling. By using secondary steam to act on the steam box, the overall steam consumption can be reduced by 30%, saving costs.

[0079] As an optional implementation, in step S7, the number of fans is 3 sets, and the air volume of each set of fans is 120m³. 3 / min.

[0080] In the actual preparation process, because the rice noodles have high surface viscosity after exiting the steamer and are prone to sticking to the conveyor belt, three sets of fans are used, each with an air volume of 120m³ / h. 3 / min, blow dry the rice noodles to remove surface moisture and reduce surface stickiness, making them easier to handle.

[0081] The present invention will now be described in detail with reference to embodiments and experimental data.

[0082] Example 1

[0083] A method for preparing semi-dried rice noodles includes the following preparation steps:

[0084] S1. Weighing: Weigh 40kg of rice flour, 7.5kg of corn starch, and 2.5kg of potato starch respectively; the rice flour has a protein content of more than 8g / 100g, a fat content of 2%, a soluble sugar content of 0.4%, and a straight-chain starch content of 21%.

[0085] S2. Mixing: Weigh 50kg of water, 40kg of rice flour, 7.5kg of corn starch, and 2.5kg of potato starch, with a flour-to-water ratio of 1:1. Add 100g of edible flavoring. First, mix the water and flour at a frequency of 15Hz. Then, pour the mixture into a storage tank and mix it further by stirring (at a frequency of 25Hz) to complete the mixing of the flour slurry.

[0086] S3. Mashing: The slurry obtained in step S2 is fed into the gelatinizer at a uniform feed rate of 50 mL / s. The steam valve is opened, and the pressure of the gelatinizer is adjusted to 0.050 MPa-0.065 MPa. The internal gelatinization temperature is raised to 95℃-110℃ by steam pressurization and heating. At the same time, the gelatinization temperature and pressure of the gelatinizer are kept stable. The total gelatinization time from the material entering from the inlet to the material exiting from the outlet is 2 min-3 min, so that the gelatinization is complete and uniform.

[0087] S4. Extrusion: The gelatinized material in step S3 is directly fed into the extrusion cylinder of the extruder integrated with the curing machine and extruded into rice noodles. The extrusion orifice diameter is 1.8mm, the total number of orifices is 216, and the orifice spacing is 3.0mm. The extrusion cylinder uses two diversion baffles at the two ends to allow the gelatinized material to be extruded into rice noodles at a uniform speed through the extruder. The diversion baffle is divided into two parts, which are composed of diamond-shaped plates with a width of 80mm, a length of 600mm, a thickness of 12mm in the middle and 3mm on both sides. There are 8 small holes with a diameter of 10mm in the middle of the diversion baffle, and the spacing between each small hole is 20mm.

[0088] S5. Steaming box: Place the rice noodles extruded in step S4 on the conveyor belt and steam them. The steaming box is divided into three sections of equal size, each with a different temperature. The temperature of the first section is 65-70℃, the temperature of the second section is 75-85℃, and the temperature of the third section is 70-80℃. The steaming time for each section is 1 minute, and the total steaming time is 3 minutes.

[0089] S6. Spraying emulsified oil: Spray the rice noodles with a 2% concentration of emulsified oil, which is a mixture of 30% phospholipids, 40% palm oil, 15% glycerol fatty acid esters and 15% soybean oil. The ratio of rice noodles to emulsified oil is 400:1. Use 6 atomizing nozzles to spray the emulsified oil evenly onto the surface of the rice noodles using compressed air.

[0090] S7. Cooling: Turn on 3 sets of fans to dry the surface moisture of the rice noodles, with an airflow of 120m³ / h per set. 3 / min;

[0091] S8. Cutting and Packaging: The rice noodles on the conveyor belt are neatly cut into 20cm long strips by an automatic cutter at a frequency of 31.0. Then, the rice noodle strips are folded in half at both ends for packaging. The folded rice noodles are automatically fed into the pillow-type packaging machine via the conveyor belt. During packaging, a chain-type 30-type three-proof deoxidizer is added to the rice noodle cake by an automatic bag-feeding machine. The packaging size is 180mm*120mm, the film thickness is 6 mils, and the film material is KNY+CP. The speed is 50 bags per minute.

[0092] S9. Freezing and loosening: Freeze the rice noodles packaged in step S8 at -18℃ to -20℃ for 3 hours, and then thaw naturally to obtain semi-dried rice noodles.

[0093] Figure 1 This is a diagram of the rice noodles extruded in step S4 of this embodiment. From... Figure 1 As can be seen, the extruded rice noodles are distinct, uniformly extruded, and produced at a consistent speed. They are smooth, of uniform thickness, and without any breaks.

[0094] Figure 3 This is a photograph of step S6, spraying emulsified oil, in this embodiment.

[0095] Weigh out rice flour, corn starch, and potato starch separately, with proportions of 40%-45%, 5%-7.5%, and 2.5%-5%.

[0096] Example 2

[0097] Compared with Example 1, the only difference is that in step S1, rice flour, corn starch and potato starch are weighed in a weight ratio of 40:5:5.

[0098] Example 3

[0099] Compared with Example 1, the only difference is that in step S1, rice flour, corn starch and potato starch are weighed in a ratio of 45:5:2.5.

[0100] Example 4

[0101] The only difference from Example 1 is that in step S9, the temperature is frozen at -18°C to -20°C for 4 hours.

[0102] Comparative Example 1

[0103] A method for preparing semi-dried rice noodles includes the following preparation steps:

[0104] S1. Weighing: Weigh out 20kg of Hunan rice flour, 17kg of Northeast Beidahuang rice flour, 8kg of corn starch, and 5kg of potato starch.

[0105] S2. Mixing: Weigh out 50kg of water and mix it with 20kg of Hunan rice flour, 17kg of Northeast rice flour, 8kg of corn starch and 5kg of potato starch. Then add 100g of edible flavoring. First, use a low-speed mixer at 15Hz to basically mix the water and powder. Then, pour it into a storage tank and mix it further by stirring (at 25Hz) to complete the slurry mixing.

[0106] S3. Mashing: The slurry obtained in step S2 is pumped into the feed inlet of the gelatinizer at a constant speed using a rotor pump. The feed flow rate is 45ml / s-50ml / s. The feed is then gelatinized. The gelatinization temperature is 95℃-110℃. The gelatinizer is heated by steam pressurization at a pressure of 0.045MPa-0.060MPa to stabilize the gelatinization temperature and the pressure of the gelatinizer. The frequency of the gelatinizer is 35Hz to ensure complete and uniform gelatinization.

[0107] S4. Extrusion: The gelatinized material in step S3 is directly fed into the extrusion cylinder of the extruder, which is integrated with the curing machine, and extruded into rice noodles. The extrusion orifice diameter is 1.8mm, the total number of orifices is 216, and the orifice spacing is 3.0mm. The extrusion cylinder uses two diversion baffles at both ends to allow the gelatinized material to be extruded into rice noodles at a uniform speed through the extruder. The diversion baffle is divided into two parts, which are composed of diamond-shaped plates with a width of 80mm, a length of 600mm, a thickness of 12mm in the middle and 3mm on both sides. There are 8 small holes with a diameter of 10mm in the middle of the diversion baffle, and the spacing between each small hole is 20mm.

[0108] S5. Steaming box: Place the rice noodles extruded in step S4 on the conveyor belt and steam them in the steaming box. The steaming box is divided into three sections of equal size, each with a different temperature. The temperature of the first section is 60-65℃, the temperature of the second section is 70-80℃, and the temperature of the third section is 70-75℃. The steaming time is 4 minutes.

[0109] S6. Spraying emulsified oil: Spray the rice noodles with a 2% concentration of emulsified oil, which is a mixture of 30% phospholipids, 40% palm oil, 15% glycerol fatty acid esters and 15% soybean oil. The ratio of rice noodles to emulsified oil is 400:1. Use 6 atomizing nozzles to spray the emulsified oil evenly onto the surface of the rice noodles using compressed air.

[0110] S7. Cooling: Turn on 3 sets of fans to dry the surface moisture of the rice noodles, with an airflow of 120m³ / h per set. 3 / min;

[0111] S8. Cutting and Packaging: The rice noodles on the conveyor belt are neatly cut into 20cm long strips by an automatic cutter at a frequency of 31.0. Then, the rice noodle strips are folded in half at both ends for packaging. The folded rice noodles are automatically fed into the pillow-type packaging machine via the conveyor belt. During packaging, a chain-type 30-type three-proof deoxidizer is added to the rice noodle cake by an automatic bag-feeding machine. The packaging size is 180mm*120mm, the film thickness is 6 mils, and the film material is KNY+CP. The speed is 50 bags per minute.

[0112] S9. Freezing and loosening: Freeze the rice noodles packaged in step S8 at -18℃ to -20℃ for 3 hours, and then thaw naturally to obtain semi-dried rice noodles.

[0113] Comparative Example 2

[0114] A method for preparing semi-dried rice noodles includes the following preparation steps:

[0115] S1. Weighing: Weigh 20kg of Hunan rice flour, 20kg of Northeast rice flour, 6kg of corn starch, and 4kg of potato starch respectively.

[0116] S2. Mixing: Weigh out 50kg of water and mix it with 20kg of Hunan rice flour, 20kg of Northeast rice flour, 6kg of corn starch and 4kg of potato starch. First, use a low-speed mixer at a frequency of 15Hz to basically mix the water and powder. Then add 0.1% of edible flavoring and then pour it into a storage tank for further mixing (at a frequency of 25Hz) to complete the slurry mixing.

[0117] S3. Mashing: The slurry obtained in step S2 is pumped into the feed inlet of the gelatinizer at a constant speed using a rotor pump. The feed flow rate is 50 ml / s, and the feed is gelatinized. The gelatinization temperature is 100℃-115℃, and the temperature is increased by steam pressurization at a pressure of 0.060 MPa-0.070 MPa. At the same time, the frequency of the gelatinizer is adjusted to 35 Hz to ensure complete and uniform gelatinization. After the gelatinization is completed, the powder enters the extrusion stage.

[0118] S4. Extrusion: The gelatinized material in step S3 is directly fed into the extrusion cylinder of the extruder integrated with the curing machine and extruded into rice noodles. The extrusion orifice diameter is 1.8mm, the total number of orifices is 216, and the orifice spacing is 3.0mm. The extrusion cylinder uses two diversion baffles at the two ends to allow the gelatinized material to be extruded into rice noodles at a uniform speed through the extruder. The diversion baffle is divided into two parts, which are composed of diamond-shaped plates with a width of 80mm, a length of 600mm, a thickness of 12mm in the middle and 3mm on both sides. There are 8 small holes with a diameter of 10mm in the middle of the diversion baffle, and the spacing between each small hole is 20mm.

[0119] S5. Steaming box: Place the rice noodles extruded in step S4 on the conveyor belt and steam them. The steaming box is divided into three sections of equal size, each with a different temperature. The temperature of the first section is 70-75℃, the temperature of the second section is 80-85℃, and the temperature of the third section is 75-80℃. The steaming time is 3 minutes.

[0120] S6. Cooling: Turn on 4 sets of fans to dry the surface moisture of the rice noodles, with an airflow of 120m³ / h per set. 3 / min;

[0121] S7. Cutting and Packaging: The rice noodles on the conveyor belt are neatly cut into 20cm long strips by an automatic cutter at a frequency of 32.0. The rice noodle strips are then folded in half at both ends for packaging. The folded rice noodles are automatically fed into a pillow-type packaging machine via a conveyor belt. During packaging, an automatic bag-feeding machine adds a chain-type 30-type three-proof deoxidizer to the rice noodle cake. The packaging size is 180mm*120mm, the film thickness is 6 mils, and the film material is KNY+CP. The machine processes 50 bags per minute.

[0122] S8. Freezing and loosening: Freeze the rice noodles packaged in step S8 at -18℃ to -20℃ for 6 hours. After the frozen rice noodles are thawed naturally, they need to be loosened by hand. After the rice noodle cake is loosened, it is stored in the warehouse.

[0123] Comparative Example 3

[0124] The only difference from Example 1 is that in step S9, the temperature is frozen at -18°C to -20°C for 2 hours.

[0125] Comparative Example 4

[0126] The only difference compared to Example 1 is that no emulsified oil was sprayed.

[0127] Comparative Example 5

[0128] The only difference from Example 1 is that in step S6, a 4% concentration of emulsified oil is sprayed.

[0129] Comparative Example 6

[0130] Compared with Example 1, the only difference is that the emulsified oil is added directly along with the powder during the stirring process in step S2, and the amount of emulsified oil added is 1% of the total amount of dry rice flour.

[0131] Comparative Example 7

[0132] The only difference from Example 1 is that the emulsified oil formulation is: 25% phospholipids, 40% palm oil, 20% glycerol fatty acid esters and 15% soybean oil.

[0133] Comparative Example 8

[0134] The only difference from Example 1 is that the emulsified oil formulation is: 40% phospholipids, 35% palm oil, 10% glycerol fatty acid esters and 15% soybean oil.

[0135] The following experimental examples illustrate the beneficial effects of the present invention. Experimental methods not specifying particular conditions in the following examples are generally performed according to national standards. If no corresponding national standard exists, then generally accepted international standards, standard conditions, or conditions recommended by the manufacturer shall be followed.

[0136] Experimental Example

[0137] I. Sensory evaluation

[0138] Sensory evaluation can directly reflect the taste indicators of a product.

[0139] Appearance evaluation of Example 1: The rice noodles have no odor and have a slight rice noodle aroma; the color of the rice noodles is natural, showing the luster of the rice itself, white with a slight yellow tinge, the overall color is consistent, the surface is not white, and it is semi-transparent. In terms of appearance, the rice noodles are uniform, straight, smooth, without broken strips, and elastic. There are no impurities inside the bag.

[0140] Evaluation of the appearance of Guangxi Daohe Guan Suoxian Rice Noodles: The rice noodles have no odor, but have a slight fermented smell; the color of the rice noodles is natural, slightly yellowish, and the overall color is consistent, with no whitening on the surface. In terms of appearance, the rice noodles are uniform and straight, but the ends are a bit uneven, with visible small white clumps, no broken strips, insufficient elasticity, and the rice noodles are a bit hard. There are no impurities inside the bag.

[0141] Evaluation of the appearance of Kunming Guanrenqiao Fresh Rice Noodles: The rice noodles have no odor and have a slight aroma of rice noodles; the color of the rice noodles is natural, with an overall white color mixed with a hint of beige, and the overall color is consistent without any whitening on the surface. In terms of appearance, the rice noodles are not uniform in thickness and are generally messy and bent when packaged. The length of the rice noodles is inconsistent, and there are occasional broken pieces. The elasticity is half. There are no impurities inside the bag.

[0142] Sensory evaluations were conducted on the semi-dried rice noodles prepared in Examples 1-3 and Comparative Examples 1-2, as well as commercially available Guangxi Daohe Guansuo Fresh Rice Noodles and Guizhou Qiansuanwang Semi-dried Rice Noodles. The sensory evaluation results are shown in the table below:

[0143] Table 1 Oral Sensitivity Assessment Form

[0144]

[0145] As can be seen from Table 1, Example 1 has good hardness and smoothness, and a good chewy texture; Example 2 is too soft, and becomes slightly sticky and soft after brewing, and the rice noodles are not smooth enough; Example 3 is too hard, and the rice noodles lack toughness and have poor viscosity. Compared with Example 1, Example 1 has moderate hardness, and the rice noodles are smooth and tough; Comparative Example 1 has a slightly worse taste than Example 1; while Comparative Example 2 is too hard, breaks when brewed, has low toughness, and lacks a chewy texture; compared with Guizhou Qian Suan Wang semi-dried rice noodles, it mainly lacks toughness, is not as smooth as Example 1, and the soup is also cloudy and white; while Guangxi Daohe Guan rice noodles are mainly characterized by a serious cloudy soup after brewing, the rice noodles are too soft, lack toughness, and the surface of the rice noodles is sticky when eaten, while the center is hard.

[0146] II. Texture data analysis was performed on the semi-dried rice noodles of Example 1 and commercially available Guangxi Daohe Guansuo Fresh Rice Noodles and Kunming Guanrenqiao Rice Noodles before and after soaking or cooking. The results are shown in the table below:

[0147] Table 2. Results of Texture Data Analysis

[0148]

[0149] Table 2 shows that the hardness of the rice noodles varied significantly before brewing, but decreased after brewing. Overall, the hardness, elasticity, chewiness, adhesiveness, and tensile strength of the rice noodles in Example 1 were higher than those of Guangxi Daohe Guansuo Fresh Rice Noodles and Guanrenqiao Rice Noodles before and after brewing. However, the adhesiveness and resilience were almost the same as the other two. The data shows that Example 1 has a better chewiness and is more competitive in terms of toughness compared to the other two.

[0150] III. Comparison of Rice Noodle Brewing Effects

[0151] The effects of brewing or cooking the semi-dried rice noodles of Example 1 were compared with those of fresh and wet rice noodles from Guangxi Daoheguan, fresh and wet rice noodles from Kunming Guanrenqiao, and semi-dried rice noodles from Qujing. The comparison results are shown in Figure 4.

[0152] Figure 4 shows a comparison of the effects of rice noodles after brewing. Figure 4(a) shows the brewing of semi-dried rice noodles in Example 1 of the present invention, Figure 4(b) shows the brewing of fresh rice noodles from Guangxi Daoheguan, Figure 4(c) shows the cooking of semi-dried rice noodles from Qujing Siwei, and Figure 4(d) shows the cooking of fresh wet rice noodles from Kunming Guanrenqiao. As can be seen from Figure 4, the rice noodles of the present invention have a clear broth after brewing, without any mushy texture, and are uniform in size without any broken strands. In addition, the rice noodles are evenly dispersed and there is no sticking or clumping. Comparing the brewing results of Guangxi Daoheguan Fresh Rice Noodles, the soup turned white and cloudy after brewing, with a lot of starch precipitating out, and the rice noodles occasionally broke when picked up. Qujing Siwei Semi-dried Rice Noodles were also similar to Daoheguan, with the soup turning white and cloudy after cooking, a lot of starch precipitating out, and the rice noodles occasionally breaking. Finally, Kunming Guanrenqiao Rice Noodles had a clear soup after cooking without any thickening, but the rice noodles broke quite noticeably and were rather hard and curved.

[0153] IV. Pine Fiber Effect Experiment

[0154] 1. The loosening effect, taste evaluation, and texture analysis of rice noodles in Examples 1, 4, and Comparative Examples 3-8 were compared. The results are shown in Tables 3-5.

[0155] Table 3 Comparison of Pine Silk Experiment Examples and Effects

[0156]

[0157]

[0158] Table 4. Taste Evaluation Table of Pine Floss Experiment Examples

[0159]

[0160]

[0161] Table 5. Texture data of pine needles in experimental examples.

[0162]

[0163] Loosening condition: As can be seen from Table 3, the loosening effect of Example 1 is better. After thawing, no force is required and most of the rice noodle cakes are in a loose state. The rice noodle cakes can be basically loosened by applying slight pressure. The freezing of each layer on the entire freezer is relatively uniform, and the overall loosening condition is basically consistent. There are no cases where the rice noodle cakes cannot be loosened.

[0164] Example 4 showed better loosening effect; the rice noodle cake could be easily broken apart with a gentle tap and could be completely loosened with slight force. The effect was basically the same as freezing for 3 to 4 hours. However, the freezing time was longer than that of Example 1. From the perspective of saving energy and resources, Example 1 was better.

[0165] The loosening effect of Comparative Example 3 was minimal, and the state was almost the same as before freezing. The rice noodle cake that was frozen at -18℃ for 2 hours failed to freeze and its state was the same as before freezing, except that the temperature of the rice noodle cake dropped (1-5℃).

[0166] The loosening effect of Comparative Example 4 was average. The center of the rice noodle cake was not completely frozen. After thawing, the whole rice noodle cake still had the shape of a rice noodle cake. After applying external force to knead it, 30% of the rice noodles were still sticky and clumped together. Figure 5 This is a comparison diagram of the rice noodles in Example 1 and Comparative Example 4 after opening the bag and not being subjected to force.

[0167] The loosening effect of Comparative Example 5 was better. The rice noodles were loose before freezing and basically separated after freezing without external force. However, the high concentration of emulsified oil spraying would cause additional production costs, and the loosening effect was basically the same as that of the 2% concentration. In addition, the 4% concentration of emulsified oil spraying had obvious oil mist overflow, which posed a high safety hazard. The large amount of oil mist during spraying would result in a large amount of emulsified oil residue in the equipment, which would increase the difficulty of cleaning the workshop.

[0168] The loosening effect of Comparative Example 6 is average. Because after the emulsified oil and powder are mixed and cooked in a cooking machine, a starch film is formed on the surface of the rice noodles. Most of the emulsified oil is locked inside the rice noodles, and only the water can be extracted from the outside of the film. Therefore, after thawing, the rice noodle cake is loose, and most of it can only be loosened after applying external force and kneading.

[0169] The loosening effect of the rice noodle cake in Comparative Example 7 was average. After thawing, the rice noodle cake was loose, and most of it could only be loosened after applying external force and kneading.

[0170] The loosening effect of ratio 8 was average. After thawing, the rice noodle cake was loose, and most of it could only be loosened after applying external force and kneading.

[0171] Tables 3-5 show that Examples 1, 4, and Comparative Example 5 have good loosening effect and good taste; Comparative Example 4 did not spray emulsified oil and had the worst loosening effect; Comparative Example 6 added emulsified oil along with the powder during the mixing stage and had a mediocre loosening effect.

[0172] In terms of texture, Comparative Example 6 was slightly softer, and the starch exudation rate was slightly higher than other samples. The viscosity upon entry was slightly too sticky, giving a feeling of starch paste on the tongue. Comparative Example 4 was harder, and the chewing sensation was too high.

[0173] In summary, Example 1 demonstrates a superior loosening effect, excellent taste, and lower cost. The emulsified oil spraying method of this invention exhibits excellent anti-sticking and loosening effects, allowing the noodles to loosen after 3 hours of freezing at -18℃, eliminating the need for further manual or external force to break them apart. Compared to existing rice noodle production methods (freezing at -15℃ to -18℃ for 8 hours), this method shortens the freezing time by approximately 5 hours, significantly reducing the cost of the loosening process.

[0174] 2. An odor comparison was made between the rice noodles of Examples 1, 4, and Comparative Examples 3-8. After brewing, the rice noodles of Examples 1, 4, and Comparative Examples 3 / 4 / 5 / 6 / 7 / 8 had no odor. The oil odor of the sprayed emulsified oil product was small and almost undetectable, and did not affect the taste.

[0175] Comparative Example 5 had a concentration of 4%, twice that of Example 1. After spraying, the residual emulsified oil on the surface of the rice noodles was also more visible than in Example 1. Therefore, a slight oily odor could be smelled after opening the bag, and a thin layer of oil film clearly floated on the surface of the soup after brewing. In Comparative Example 6, the emulsified oil was added to the rice flour mixture during stirring. The amount of emulsified oil added was 1% of the total dry rice flour, equivalent to 0.5% of the rice flour mixture. In Example 1, the weight ratio of emulsified oil to rice noodles was 1:400, equivalent to 0.25% of the total rice noodles. Therefore, the emulsified oil content of Comparative Example 6 was twice that of Example 1. Thus, Comparative Example 6 and Comparative Example 5 had the same emulsified oil content in their rice noodles. A slight oily odor could also be smelled after opening the bag, and a thin layer of oil film clearly floated on the surface of the soup after brewing.

[0176] Comparative Example 7 / 8 only changed the concentration of emulsified oil, and other parameters were the same as in Example 1. The taste and texture of Comparative Example 7 / 8 were also basically the same as in Example 1. However, the loosening effect of Comparative Example 7 / 8 after freezing was not as good. In contrast to Example 1, the rice noodles were almost completely loose after freezing. Comparative Example 7 / 8 still had clumping and sticking after freezing, and failed to loosen most of the rice noodle cake.

[0177] V. Microbiological Testing

[0178] The rice noodles from Example 1 were subjected to storage microbial testing, and the results are shown in the table below:

[0179] Table 6. Detection of stored microorganisms

[0180]

[0181]

[0182] As can be seen from Table 6, the semi-dried rice noodles of the present invention maintain the authenticity of rice noodles to the greatest extent while extending the shelf life. According to the GB17400 microbial limit table, the semi-dried rice noodles produced by the present invention can meet the food safety standards within 7.2 months.

[0183] In summary, the rice noodles of this invention have the characteristics of low breakage rate, resistance to soaking and boiling, and smoothness. They are also elastic, have a pure taste, moderate hardness, and strong resistance to boiling or soaking. During consumption, the noodles do not clump together, and each noodle is distinct and does not stick together. They can be prepared by soaking or boiling, and both methods ensure the noodles retain their toughness, elasticity, and smoothness. Regardless of whether they are boiled or soaked, they are not prone to breaking or becoming mushy. The rice has a rich aroma, no special odor, a smooth and glossy surface, and uniform thickness. They can maintain a shelf life of more than six months at room temperature, with all microbial indicators below 10. Throughout the shelf life, the rice noodles remain stable and do not become mushy, with minimal change in taste, providing consumers with the best taste even after six months.

[0184] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a semi-dry noodle, characterized by, The preparation steps include: S1, weighing: rice flour, corn starch and potato starch are weighed according to the weight ratio (40-45):(5-7.5):(2.5-5), wherein the protein content of the rice flour is 6%-8%, the fat content is 1.7%-2.2%, the soluble sugar content is 0.3%-0.6%, and the amylose content is 18%-25%; S2, stirring: the rice flour, corn starch, potato starch and water in step S1 are mixed and stirred to obtain a powder slurry; S3, maturation: the powder slurry obtained in step S2 is uniformly punched into a maturation machine at a feeding flow rate of 50 mL / S, the steam valve is opened, the pressure of the maturation machine is adjusted to 0.050-0.065 MPa, the internal maturation temperature is increased to 95-110 DEG C through steam pressure boosting and warming, and the maturation temperature and pressure of the maturation machine are kept stable, and the total maturation time of the material from the feeding port to the discharging port is 2-3 min; S4, extrusion: the material in step S3 is extruded into rice noodles in the extrusion barrel of the extruder; S5, steaming: the rice noodles extruded in step S4 are placed on a conveying belt and passed through a steaming box; S6, spraying emulsified oil: after the rice noodles pass through step S5, the rice noodles are sprayed with emulsified oil with a concentration of 2%, the emulsified oil is prepared by mixing 30% phospholipid, 40% palm oil, 15% glycerol fatty acid ester and 15% soybean oil, and the weight ratio of the rice noodles to the emulsified oil is 400:1, so that a thin oil film is formed on the surface of the rice noodles, and no obvious oil is observed by naked eye observation; S7, cooling: the fan is turned on to dry the surface moisture of the rice noodles; S8, shearing and packaging: the rice noodles on the conveying belt are cut into strips of the required length by an automatic cutter, and then the rice noodles are packaged and deoxidizing agent is added; S9, frozen rice noodles: the packaged rice noodles in step S8 are frozen at-18 DEG C to-20 DEG C for 3-4 h, and then naturally thawed to obtain semi-dry rice noodles.

2. A process for the preparation of a semi-dry rice noodles as claimed in claim 1, wherein, In step S2, the total weight of the rice flour, corn starch and potato starch is 1:1 with the weight of the water.

3. A process for the preparation of a semi-dry rice noodles as claimed in claim 1, wherein, In step S2, the edible essence is added before stirring, and the amount of the edible essence is 0.1% of the total weight of the rice flour, corn starch, potato starch and water; the stirring is first stirred at a frequency of 15 Hz for 10-15 min, and then further stirred at a frequency of 25 Hz for 5 min.

4. A process for the preparation of a semi-dry rice noodles as claimed in claim 1, wherein, In step S3, the frequency of the maturation machine is adjusted to 35 Hz, that is, the rotating speed of the double screw of the maturation machine is 220 r / min, and the blade spacing between the threads is 20.0 mm.

5. The method of preparing a semi-dry rice line according to claim 1, wherein, In step S4, the feeding port of the extruder is tightly connected with the discharging port of the maturation machine in step S3.

6. The method of preparing a semi-dry rice line according to claim 1, wherein, In step S4, the maturation material is uniformly extruded into rice noodles through the extruder by using two end flow baffles in the middle of the extrusion barrel, the flow baffles are rhombus plates with a width of 80 mm, a length of 600 mm, a thickness of 12 mm in the middle and a thickness of 3 mm on both sides, and 8 small holes with a diameter of 10 mm are opened in the middle of the flow baffles, and the spacing of each small hole is 20 mm.

7. The method of preparing a semi-dry rice line according to claim 1, wherein, In step S5, the steaming box is divided into three sections of equal size, each section having a different temperature, the first section having a temperature of 65-70°C, the second section having a temperature of 75-85°C, and the third section having a temperature of 70-80°C, and the steaming box has a passing time of 3 minutes.

8. The method of claim 1, wherein the semi-dry noodles are prepared by the steps of: In step S7, the number of fans is 3 groups, and the air volume of each group of fans is 120 m 3 / min.

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