CN1030684C - Method for continuous production of quick-cooking food - Google Patents

Abstract

Extrusion of quick-cooking food products in a low-temperature process whereby the partially pre-cooked food product mixture produced in the preconditioner is passed along the length of the screw extruder through a cooking zone and then through a degassing zone And the forming zone, and finally through the extrusion die to obtain the extruded product. In the case of noodle products, the ability of the product to resist overcooking is increased to improve the quality of extruded noodles and maintain the integrity of the original product, so that the mixture is subjected to less shear during the cooking process and reduces The time required to rehydrate the extruded product.

Description

Method for continuous production of quick-cooking food

The present invention relates to an apparatus and method for the continuous production of food which can be easily rehydrated by immersing it in boiling or hot water for 1.5 to 5 minutes. The method includes partially precooking the food mixture using a preconditioner and using an extruder in which the food mixture advances first through a low cooking zone, then through a venting zone and a forming zone. Finally, the desired finished product is obtained through an extrusion die. When producing noodles, it is necessary to use the device of the present invention to remove a large amount of water from the mixture of flour and water in the exhaust area, so that a large amount of steam can be directly injected into the mixture in the hot cooking area, and the noodle products will not be affected at this time. Excessive shear forces would act which would impair the integrity of the finished product, or would undesirably raise the temperature of the mixture to a value which would locally scorch the mixture and form dark spots in the extruded product.

Another, in the production of rice products, by directly injecting steam into the mixture of rice flour or rice grains and water, and then removing a certain amount of water from the mixture in the exhaust zone, so that the mixture in the extruder is subjected to the minimum mechanical force. shear. Once the extruded article is dried, it has properties such as good article integrity after rehydration and allows for overcooking without forming a tacky or sticky exterior surface.

Usual noodle products are made by uniformly mixing water and flour, such as semolina, and then pressing and extruding the mixture of flour and water through a mold to form the mixture into a desired shape. However, typical noodle products need to be boiled in boiling water for about 10-15 minutes to hydrate and gelatinize the starch and transform the extruded product into an edible state.

In recent years, attention has been continuously focused on instant noodle products. Such preparations are typically hydrated in boiling water for 3-5 minutes. These preparations can also be mixed with other foods and cooked in a microwave oven or a common heating oven, without the need to precook the preparations on the stove and drain the excess water afterwards.

U.S. Patent 3,615,667,4,230,735,4,243,690,4,423,082,4,044,165 and 4,540,592 have done a lot of efforts in improving storage, boiling and extruding, the appearance characteristics of quick-boiled noodle products, etc. A tacky surface is formed on the boiled product, as well as increased product integrity with a minimum of production time and cost including the overall energy consumption of the extrusion process.

A problem that has been observed in the processing of extruded instant noodle products in a certain way is the formation of black or dark spots in the final product produced, such a product causing poor consumer acceptance of it decreased, and may affect the taste of the product after hydration. In this regard, it was found that dark spots usually appear in the portion where the flour and water mixture temporarily sticks to the teeth of the extruder screw, and that part of the mixture is charred by being subjected to relatively high temperatures during the usual instant noodle extrusion process. . Consequently, this charred portion escapes from the screw and exits through the die opening together with the uncharred portion of the mixture, so that dark spots appear in the final product, which are easily observed by simple visual inspection.

Furthermore, many known methods for processing instant noodles place excessive shear forces on the flour and water mixture as the mixture travels through the extruder, and unfortunately excessive shearing of the flour and water mixture The deformation will give the final product a tacky surface. It also reduces the integrity of the product, which can be measured by the ability of the product to return to its original shape after hydration. Moreover, excessive shear results in increased extruder energy consumption and mechanical problems such as increased wear of extruder parts.

Accordingly, it would be desirable to provide a method and apparatus for producing instant noodles at reduced temperatures to avoid scorching and dark spots in the final product and subject the flour-water mixture to a minimum amount of mechanical shear during extrusion. change force. Such a method would advantageously overcome various problems caused by known methods, such as the formation of gas bubbles in the extruded product and reduce the allowable degree of product overcooking. It is desirable that this method utilize a certain amount of moisture during extrusion and reliably ensure that the extruded product is fully cooked before being pushed to the drying zone. In the drying zone, the article is dried with air at or slightly above room temperature for a relatively short period of time.

Rice is a well-known important grain that is the staple food for about 1/2 of the world's population. However, regardless of whether the whole rice grains are boiled with or without bran, they must be soaked in boiling water for about 30-40 minutes in order to gelatinize the starch and transform the grains into an edible state. Precooked rice, such as instant rice with husk precooking, cooks to a ready-to-eat state in about 15 minutes. In addition, precooking the groats of rice in bags or containers is undesirable and the groats are generally separated and sold as rice grains or rice flour at a discount.

In recent years, more and more technically advanced groups have focused more and more attention on quick-cooking rice products, which usually only need to be hydrated in hot or boiling water within 5-10 minutes. The advantage is that such a preparation can also be mixed with other foods and cooked hot in a microwave oven or in a conventional oven, without the need to precook the rice on the oven and remove excess water afterwards. In addition, it is known that grinding whole rice into rice flour for the production of instant cooked rice has a higher percentage of useful grains than the percentage of useful grains obtained by debraning the rice into white rice for consumption.

In general, known methods of producing instant rice include the steps of mixing a mixture of rice and water in an extruder and increasing the temperature of the mixture as it travels along the length of the extruder to gelatinize the rice starch. Unfortunately, known methods apply excessive shear forces to the rice and water mixture in the extruder, which imparts a sticky surface to the hydrated product and behaves in a somewhat unpleasant manner when served. Satisfying way to unite blocks. An excess of mechanical shear also reduces the tolerance of the extruded article to allow overcooking. This overcooking in some cases causes the hydrated rice to have an unpleasant sticky outer surface, or to become mushy and fall apart.

Excessive shear of the rice and water mixture in the extruder can, under certain circumstances, reduce the integrity of the product, which is determined by the ability of the rice product to return to its original configuration after hydration to measure. A considerable shear can also cause sticky or sticky properties, which will deteriorate the quality of the product. Also very large shear can lead to increased energy consumption of the extruder and many parts due to extrusion. Mechanical problems caused by greater wear at elevated temperatures.

Accordingly, it would also be desirable to provide an apparatus and method for the production of quick-cooked rice that works by reducing the mechanical shear applied to the rice and water mixture with the aim of improving the properties of the extruded product and reducing the pressure of the extruder. energy consumption and maintenance costs. This method expects to utilize a relatively large amount of moisture during the cooking process in order to reduce shear, while ensuring that the extruded product can be fully cooked before proceeding to the drying zone, where the product passes through a very short period of time. Air at ambient temperature or slightly above this temperature is used for drying.

The present invention overcomes the above-mentioned disadvantages by utilizing a low-temperature extrusion method to produce quick-cooking noodle products, which method comprises: passing the noodle-making flour and water mixture through a preconditioner for 20 seconds to 3 minutes to Partially precook the mixture at a temperature in the range of 150°F-210°F, and then introduce the mixture into the extruder, passing first through a cooking zone, then through a venting zone and a forming zone, and finally through an extrusion die An extruded article is obtained. The mixture is treated to have a maximum temperature of about 215°F, preferably a maximum temperature of 205°F, in order to substantially eliminate the possibility of partial darkening and charring in the extrudate. However, if it is desired to use lower temperatures, the maximum temperature may not exceed 185°F, and the pressure in the extruder may be in the range of 200 psig to 1200 psig.

Importantly, the placement of the venting zone in the extruder according to the present invention causes a substantial amount of moisture to be removed from the flour and water mixture in the form of gas. Thus, as the mixture progresses through the cooking zone, the ratio of water to flour in the mixture may be increased, which reduces the viscosity of the mixture and accordingly reduces the shear forces applied to the mixture. The extruded product has good integrity after hydration, so that the surface of the product is notably free of a sticky feel and appearance, and the resulting product has greater tolerance to excessive heat cooking, which Tolerance is not observable from changes in sensory properties.

The mixture of flour and water is exposed to the exhaust area of the extruder, allowing it to gradually cool before entering the forming area and the die. For this reason, the extruded product is processed before it reaches the drying stage because the product retains its shape. Easy and clean cuts can be made with the cutter held on the face of the mold without tearing the noodles. In addition, forming the mixture at cooler temperatures reduces the stickiness and volume of air bubbles in the product, which reduces the likelihood that the extruded product will clump and become unsalable.

It has been found that applying negative pressure to the exhaust zone of the extruder reduces the time required to hydrate the product produced by about 1 minute and substantially prevents the formation of air bubbles within the extruded product, thereby increasing the final Product transparency. Extruder venting also greatly reduces the moisture content of the mixture, improving the quality of the final product. In a preferred form of the invention, the exhaust zone is equipped with a device whose conical housing is connected to an exhaust hole and a vertical screw is mounted in the housing, the screw having helical teeth, so that the flour entering the housing and Any diverted portion of the water mixture is fed back into the extruder in the opposite direction to the exhaust gas flow.

The present invention further overcomes the deficiencies mentioned above. That is, the production of quick-cooking rice products using a low-shear extrusion process that involves passing a mixture of rice flour or rice particles and water through a preconditioner for 20 seconds to 3 minutes to The step of partially precooking the mixture at a temperature in the range of 210°F, and then feeding the mixture into the extruder, passing first through a cooking zone, then through a venting zone and a forming zone, and finally through an extrusion die to obtain an An extruded product. The temperature of the mixture in the cooking zone is in the range of about 180°F-350°F, preferably in the range of 235°F-265°F, and the pressure in the extrusion vessel of the extruder is in the range of 200psig-1200psig Inside.

Particular attention should be paid to the provision of a degassing zone within the extrusion device according to the principles of the present invention, which will allow a certain amount of moisture to be removed from the rice and water before the mixture is fed into the forming zone and subsequent dies in the form of a gaseous product. removed from the mixture. Therefore, the proportion of water and rice in the mixture can be increased when the mixture advances to the cooking zone, in order to reduce the viscosity of the mixture, thereby reducing the shear force applied to the mixture accordingly, so that the extruded product can be heated in water. After curing, it presents good integrity, and the surface of the product obviously does not have the feeling and appearance of stickiness. In addition, the product has a greater tolerance to excessive cooking that is not observable from changes in organoleptic properties. The extrusion method utilizes the more difficult-to-market broken rice grains and/or powders to form a product that, when hydrated, has the properties and appearance of parboiled whole grains of rice.

The rice and water mixture is exposed to the exhaust zone of the extruder and the mixture is slowly cooled before being introduced into the forming zone and dies. For this reason, the extruded article is easy to handle before it reaches the drying zone, since the article retains its shape and can make clean cuts without tearing with the blades held against the die face.

It has been found that the removal of moisture from the mixture is facilitated by applying negative pressure to the vent area of the extruder. This improves the quality of the final product while also allowing the moisture content of the mixture to increase in the cooking zone, minimizing mechanical shear. The exhaust area is equipped with a device with a conical shell connected to the exhaust port. A vertical screw is installed in the shell. The screw has helical teeth, so that any part of the partially deflected rice and water mixture is directed towards the exhaust gas. The air flow is directed back into the extruder in the opposite direction.

Other features and advantages of the present invention can be more clearly described from the following selected embodiments in conjunction with the accompanying drawings. in,

Figure 1 is a fragmentary side view illustrating in schematic fashion an extruder for reheating and extruding a food mixture in accordance with the principles of the present invention.

Figure 2 is an enlarged partial plan view of the extruder shown in Figure 1, partially in section, revealing the paired, helically toothed screws disposed within the extruder vessel.

Figure 3 is a graph showing a typical temperature profile of a flour and water mixture for making instant noodles along the length of the preconditioner and extruder tunnels shown in Figure 1 in accordance with the present invention.

Figure 4 is a graph showing a typical temperature profile for preparing a parboiled rice and water mixture along the length of the preconditioner and extruder tunnel shown in Figure 1 in accordance with the present invention.

See Fig. 1, wherein 10 represents extruding place, and it comprises: an extruder 12 with cylinder 14, and its inlet is that 16 is positioned at the outlet below preprocessor 15, and extruder 12 also has the outlet of a band mold 18, The cylinder 14 described is composed of nine cylinder sections 20-36, although the number of cylinders can be varied without departing from the principles of the present invention.

As shown in Figure 2, the extruder barrel 14 has walls defining a chamber 38 consisting of two cylindrical, juxtaposed interconnected chamber regions, two rotatable screw-toothed material Traveling screws 40 are housed in various zones of the chamber 38 and intermesh along most of the length of the extruder barrel, but are separated from each other in the final barrel zone 36 and are located in respective complementary tapered In the cylinder area, in order to separate the processed mixed material to form two juxtaposed, disconnected effluent columns.

The twin-screw food extruder 12 shown in FIG. 2 is produced by Wenger Manufacturing Company, the assignee of the present invention, and is referred to as the Wenger-TX type extruder in the Wenger Bulletin, No. 56, page 586. In this regard, it is deliberately pre-disclosed here. It can be seen that the WengerTX extruder provides a relatively high pressure differential in the dual head exit zone, on the order of 500psi-600psi, and this factor is believed to be at least particularly important in achieving the unique results of the present invention.

Referring to Fig. 1, be used for the device 42 that cylinder zone 32 is carried out exhaust, it comprises: have the shell 44 of a conical part 46 and cylindrical part 48, and cylindrical part 48 is connected with conical part 46, and is connected onto the cylinder 14 of the extruder. The closed housing 44 has a structure defining a passage 50 having a conical configuration in the conical portion 46 and a corresponding cylindrical configuration in the cylindrical portion 48, the passage 50 having an outlet 52 and an inlet 54 which communicates with an exhaust hole 56 (see FIG. 2 ) in the cylindrical region 32 . The housing 44 includes a lower horizontal plate 58 in sealing contact with the exhaust port 56 for anti-leakage, which covers the exhaust port except in contact with the immediately adjacent area of the passage 50 in the cylindrical portion 48. all parts of .

The exhaust device 42 also includes: a screw with helical teeth, which is used to return the mixed material entering the channel 50 to the extruder in the direction opposite to the exhaust direction, and the vertical exhaust device screw 60 is in the The passage 50 is axially rotatable within the area including the area adjacent the passage entrance 54 and is powered by a motor 62 connected to a right angle drive 64 .

Passage outlet 52 is provided with a pipe 66, and it stretches out through the cover plate 68 of exhaust device shell 44, and pipe 66 is C font in shell 44, so its outlet 52 is directly close to cover plate 68, and pipe 66 passes through to atmosphere, or preferably to a vacuum source, to create a negative pressure in passage 50 and to draw gas from the compounded material as it travels along extruder 12.

According to one aspect of the present invention, a kind of low-temperature extruding process is used for producing quick-cooking noodle products, and it comprises: the mixture that is made up of flour and water is introduced into the barrel 14 of extruder 12, initially in preconditioner Mix flour and water within 15 to prepare a flour and water mixture while increasing the temperature of the mixture to a value in the range from 160°F to 210°F for a residence time of 20 seconds to 3 minutes, where 1 A residence time of 10 minutes to 2 minutes is optimal. A pretreatment step is also optional and includes adding steam to the flour as the mixture travels along the first 1/3 of the length in the preconditioner 15.

Desirably, prior to venting barrel zone 32, the mixture within extruder chamber 38 consists of about 80%-50% by weight flour and 20%-50% water. However, better results have been observed for the mixture prior to the venting cylinder zone 32 to consist of about 70% to 65% by weight flour and 30% to 35% water.

Once the flour and water mixture enters the extruder 12 through the inlet 16, the axial rotation of the screw 40 causes the mixture to travel the length of the barrel 14. Thus, the mixture first passes through the cooking zone in the extruder, then through the degassing zone and the forming zone, and finally through the holes 70 in the die 18 (see FIG. 2 ) to give the extruded product.

For example purposes, the cylindrical zones 20-30 shown in Figures 1 and 2 represent cooking zones through which the flour and water mixture can reach a maximum temperature of about 215°F, preferably 205°F, The residence time of the mixed material in the hot cooking zone (including the cylinder zone 20-30) is about 10 seconds-25 seconds, preferably 15 seconds.

Cylinder zone 32 represents the degassing zone already mentioned above, as the mixture of water and flour is propelled by screw 40, the gas coming out of the flour and water mixture in this zone is pre-exhausted. When the gas is discharged through the vent hole 56 and the passage 50, the screw 60 of the venting device is rotated so that any part of the flour and water mixture that deviates, that is, the mixture from the chamber 38 through the vent hole 56, is opposite to the exhaust direction. The direction is returned to the chamber 38. As can be seen in FIG. 1 , a vertical channel 50 configured with a vertical screw can cause any portion of the mixture within the channel 50 to fall towards the screw 60 under the influence of gravity. Afterwards, it returns to the chamber 38 again. If desired, a scraping element (not shown) may be placed in the conical region of the channel 50 for scraping off the accumulated portion of the flour and water mixture on the inner surface of the conical region 46 of the casing.

Preferably, the outlet 52 of passage 50 is communicated with vacuum source, provides the vacuum degree of about 5-20in·Hg·column by vacuum source, when the negative pressure of passage 50 is about 15in·Hg·column, can observe better the result of.

The tapered region of passage 50 causes the superficial velocity of the mixture entering passage 50 to drop to a relatively low level as the mixture approaches cover plate 68 to substantially prevent the mixture from entering evacuation tube 66. The exhaust outlet 52 is located at the upper corner of the passage 50, near the cover plate 68, so that there is no danger of the mixture entering the duct 66 even if a considerable amount of mixture flows temporarily into the passage 50. At the same time, the conical configuration of conical portion 46 causes the mixture therein to fall downwardly toward inlet 58 of channel 50 as motor 62 rotates the screw in the forward direction. Thus, the mixture is forced back into the chamber 38 of the cylinder.

Referring again to FIG. 1, barrel zones 34 and 36 represent forming zones through which the flour and water mixture fed is compressed and extruded through die orifice 70. The residence time of the mixture in the forming zone is from about 20 seconds to about 60 seconds, preferably about 45 seconds. Additionally, the pressure to which the mixture is subjected in the forming zone is from about 200 psig to 1200 psig, preferably 500 to 600 psig.

As the mixture is fed along chamber 38, both water and steam can be injected into the mixture, e.g., tap water can be injected into the initial barrel zone, or barrel zone 20, at a temperature in the range of 50°F to 65°F . Steam may be injected into a region downstream of the cylinder inlet 16 such as the region of the respective cylinder 24,26,28. As another example, water at a temperature of about 180°F could be injected into the initial cylinder zone 20, whereby less steam would be required. Of course, joining in other directions is also possible.

The barrel 14 of the extruder 12 is preferably jacketed so that cooling water or oil can be circulated in the extruder 12 adjacent the chamber 38 . The flour and water mixture is subjected to indirect heat transfer as they travel along the length of the cylinder 14 . Other suitable means, such as heating by resistance or induction, may also be used. Preferably the temperature of the mixture as it travels through the entire length of the extruder 12 is approximately in the range of 130°F to 210°F. Of course, it is required to be subjected to the highest temperature mentioned above in the cooking zone. Optionally, the temperature of the mixture in the forming zone can be lower than its temperature in the cooking zone.

The extrudate is cut to the desired length by means of knives held against the outer surface of the die 18 as the mixture exits the forming zone of the extruder 12 and through the die holes to give the extrudate. Afterwards, the product enters a drying zone in order to make the resulting product suitable for storage and transportation.

In the best form of the present invention, the drying step of the extruded product is carried out until the moisture in the noodle product is about 8%-14% by weight. However, it is best to make the water content of the noodle products in the range of 10%-12% by weight, which can obtain better drying results.

The extruded article undergoes the drying stage, preferably at ambient temperature or from 75°F to about 180°F for a period of about 20 minutes to 60 minutes. However, better results have been observed when the extruded article is subjected to a temperature of about 120°F to 140°F during the drying stage for a period of about 20 minutes to about 30 minutes.

It has been found that, in accordance with the principles of the present invention, low-temperature extrusion of instant-cook noodle products substantially eliminates dark and burnt spot formation in the product while reducing energy requirements. It also reduces air bubbles and increases tolerance for overcooking. And increase the taste of the product. During the cooking process, the lower temperature plus the cooling effect on the mixture provided by the exhaust device 42, thus facilitates processing and extrusion by reducing the viscosity of the product and allowing it to better retain its shape before the drying stage. Pressed products.

When the mixture passes through the exhaust zone of the extruder 12, a large amount of moisture is removed from the mixture of flour and water, and this relatively large amount of moisture can appear in the mixture when passing through the cooking zone, thereby reducing the amount of water added to the mixture. This will increase the integrity of the product after rehydration and prevent the product from being easily destroyed or broken off when it reaches an edible state, and reducing the shear added to the cooking zone mixture can also avoid Increased viscosity of the product as well as reducing the overall energy consumption of the extruder 12. Extruded products have the advantage of good resistance to overheating. The quality of the product is thus superior to that produced by known methods.

Making the vacuum greater than 5in·Hg·column in the degassing area will reduce the rehydration time by about 1 minute, that is, without the degassing stage, usually complete rehydration will occur after 4 minutes, and using the degassing stage, Complete rehydration occurred after 3 minutes. In essence, the use of vacuum in the degassing zone also prevented the formation of air bubbles in the extruded article.

FIG. 3 shows a typical temperature profile of the mixture as it travels through the preconditioner 15 and along the length of the cylinder 14. As shown in FIG. It can be seen that the temperature of the mixture increases steadily as it passes through the preconditioner 15, then increases slightly as it travels through the cooking zone, and decreases in temperature in the exhaust zone corresponding to the cylinder zone 32, after which The temperature decreases steadily as it travels through the forming zone represented by the cylindrical zones 34, 36, and the temperature of the mixture decreases further as it passes through the die orifice 70. In this example, about half of the mix is subjected to cooking within the preconditioner 15, while the remainder will be subjected to cooking as they pass through the extruder and are exposed to temperatures of 140°F-160°F.

example 1,

In this experimental example, an initial flour mix was made from 99.5% by weight semolina and 0.5% Myvaplex 600 surfactant, and this dry mix was fed into a hopper equipped with a preconditioner and a screw feeder. WengerTX-80 twin-screw extruder is processed, obtains a kind of hot boiled noodle product.

Figure 1 schematically illustrates a TX-80 extruder terminating in a twin-screw conical nozzle die head having a total of eight tubular heads or barrel zones.

The dry initial flour mixture (which has a moisture content of 12%) is fed to the preconditioner at a rate of 7.03 pounds per minute and mixed with water added to the preconditioner at a rate of 0.83 pounds per minute. The mixture of water and flour in the preconditioner is used at a speed of 0.40 pounds per minute, the pressure is 30psi, the steam injected makes it increase the temperature, the agitator in the preconditioner (it can be tilted at different angles to provide various possible dwell time) at a speed of 171 rpm and can be adjusted to allow the mixture to dwell in the preconditioner for 1.5 minutes. The mixture exiting the preconditioner had a temperature of 200F and a moisture content of about 25% by weight.

Afterwards, the mixture was sent to the feed port of the extruder located at the inlet of the cooking zone, and tap water was injected into the mixture at a rate of 0.97 pounds per minute. (Alternatively, however, hot water at a temperature of about 180°F can be added in order to reduce the required steam flow rate). The screw of the extruder rotates at a speed of 161rpm. When the mixture travels through the extruder, no steam needs to be added. The load of the extruder is 17.8KW. When there is no mixture and the screw speed is 161rpm, the load on the extruder is 2.2 KW. Therefore, the increased load required in the extruder due to the presence of the mixture is about 15.6KW.

The dual cylinder temperatures were maintained at 197°F, 195°F and 191°F for the third, fourth and fifth cylinder zones, respectively. The moisture content of the flour and water mixture in the cooking zone of the extruder was about 33% by weight. The sixth cylindrical zone included a vent for evacuation to 10 in·Hg·column. The forming zone of the extruder corresponds to the seventh and eighth barrel zones and their temperatures are 163°F and 165°F, respectively.

The speed of the product through the extruder (including the total amount of water added to the preconditioner and the extruder) was 8 1/2 pounds per minute, and the pressure at the last cylindrical area adjacent to the die was 600 psi, along the The moisture content of the extruded product from the die was 27% by weight. The die had a total open area of 0.547 square inches and the extrusion was cut with a knife to the length of macaroni elbows. The product in the drier was dried at 130°F for 24 minutes. After drying, the extruded product had a final moisture content of 11%. The resulting product hydrated in about 4 minutes and had good product integrity. and palatability. No dark or burnt spots appear.

Example 2:

In this example, the steps described in Example 1 were followed substantially except that water was injected into the preconditioner at a rate of 0.71 pounds per minute, and that the screw speed of the preconditioner was 170 rpm. The moisture content of the mixture given from the preconditioner was 26.5% by weight.

In the extruder, steam at a pressure of 125 psi is fed at a rate of 0.60 pounds per minute, and water is fed into the extruder at a rate of 0.53 pounds per minute. As a result, in the hot cooking zone of the extruder, flour and water The moisture content of the mixture was 37.5%. In this case, the load on the extruder is 15.98KW, so the load required to process the mixture in the extruder is 13.78KW.

The temperature in the third, fourth and fifth cylinder areas is maintained at 203°F, 193°F and 187°F respectively, and the sixth cylinder area is connected with a vacuum source so that the vacuum degree of the cylinder area is 15in. Hg column. The temperatures in the seventh and eighth cylindrical zones were 182°F and 177°F, respectively.

The pressure in the last, or eighth, barrel zone near the die was 500 psi and the moisture of the extruded article was 27.57%. Thus, the difference between the moisture content of the mixture in the cooking zone, and the moisture content of the extruded product represents the moisture that escapes in the vent zone, although a small amount of moisture can be removed in the form of steam at the die opening 70. In addition, the macaroni was very tasty when hydrated, intact and no dark spots were observed.

In accordance with another aspect of the present invention, a low shear extrusion process is used to prepare instant cooked rice products, the process comprising: introducing a mixture of rice flour or grains and water into the barrel of an extruder 12 , and the details of the method are different from the above-mentioned preparation of noodle products with a mixture of flour and water, adopting Fig. 1 and Fig. 2, which include a new type of exhaust cylinder area 32, is the basic device, in a generally similar manner Provides improved quick-cooking rice products, so unless specifically stated below, other parts will assume that a mixture of rice flour or rice particles and water is processed in a similar manner to the apparatus shown in Figures 1 and 2 . Their mixture is initially prepared by mixing rice and water in preprocessor 15, and the temperature of the mixture is raised to a value within the range of about 150°F to 210°F. The residence time is 20 seconds to 3 minutes, preferably 1 minute to 2 minutes. If desired, the pretreatment step may include the step of adding steam to the rice and water mixture as the mixture travels along the first 1/3 of the length of the preconditioner 15 .

It is desirable that the mixture in the extruder chamber 38 prior to the venting barrel zone 32 contain 80% to 60% by weight rice and 20% to 40% water. However, better results were observed when the mixture before the barrel zone 32 contained 75%-70% rice and 25%-30% water.

Once the rice and water mixture is introduced into the extruder 12 through the inlet 16, the axial rotation of the screw 40 is used to cause the mixture to advance along the length of the cylinder. When the cooking zone is advanced, its temperature is in the range of about 180°F-350°F, and the temperature of the mixture in the cooking zone is generally selected in the range of 210°F-300°F. Best results are observed when the temperature of the mixture in the cooking zone is in the range of 235°F-265°F. Equally, the residence time of the mixed material in the boiling zone including the cylinder zone 20-30 is about in the range of 10 seconds-25 seconds, generally about 15 seconds.

Referring again to Fig. 1, the cylindrical areas 34 and 36 represent forming areas, and the mixture advances through the forming areas before being extruded through the die hole 70, and the residence time of the mixture in the forming areas is about 20 seconds to 60 seconds, preferably 45 seconds. The temperature of the mixture is in the range of 130°F to 250°F, preferably in the range of 180°F to 220°F. Additionally, the mixture is subjected to a pressure of 200-1200 psi, preferably 500-600 psi, in the forming zone.

Water and steam can be injected into the mixture as the mixture travels along the chamber 38, for example, tap water can be injected into the initial cylinder zone or cylinder zone 20 at a temperature in the range of 50°F to 65°F, Steam may be injected downstream of the barrel inlet 16 into respective zones 24, 26 and 28. Another example is that water at a temperature of about 180°F could be added to the initial cylinder zone 20, so less steam would be required. Of course, it is also possible to join in other directions.

Preferably, the temperature of the mixture traveling along the entire length of the extruder is approximately in the range of 210°F to 250°F, and the temperature of the mixture in the forming zone can be lower than that in the cooking zone if desired .

In a preferred mode of the present invention, the step of drying the extruded product is carried out until the moisture content of the rice product is 8%-14%. However, better results have been observed for optimum rice products with moisture values in the range of 10%-12%.

The extruded article in the drying stage is preferably subjected to drying for a period of 60 minutes to 10 minutes at ambient temperature or a temperature ranging from about 75°F to about 250°F. However, during the drying stage, extruded articles are subjected to a temperature in the range of 180°F to 220°F for 10 to 20 minutes with better drying results.

When the mixture passes through the exhaust zone in the extruder 12, a certain amount of moisture is removed from the rice and water mixture, and these moisture are present in the mixture when passing through the passage of the cooking zone, due to the removal of the moisture content, thereby reducing Using the shear on the mixture, the reduction in shear in the cooking zone will reduce the likelihood that the hydrated rice product will tend to form undesired lumps due to the sticky outer surface. In addition, the overall energy consumption of the extruder 12 is reduced due to the reduced shear applied to the mixture in the cooking zone. The extruded product will increase the tolerance for overcooking without being sticky or sticky, so the quality of the product is superior to that produced by known methods.

A vacuum greater than 5 in.Hg is drawn in the exhaust area, so that a higher amount of water (either in the form of tap water or in the form of steam) can be added to the mixture traveling along the cooking area, thereby further reducing the effect on the cooking area. Mechanical shear on the mixture in an extruder. The formation of air bubbles in the extruded product can also be prevented by drawing a vacuum in the vent area.

Other ingredients can be added to the rice and water mixture to increase the properties of the extruded product, eg bulking agents such as calcium phosphate and sodium phosphate can be added before the mixture enters the cooking zone. Or alternatively, the additive can be reacted with the mass comprising the mixture to form gas bubbles within the extruded article. Therefore, the product is slightly expanded, and it is easy to enter water during hydration, reducing the time required for hydration. The processing method is not affected by the type of rice, i.e. long-grain, short-grain or brown rice, and they can be used singly or in different combinations.

FIG. 4 shows a typical temperature profile of the mixture as it travels within the preconditioner 15 and along the length of the cylinder 14 . It can be seen that as the mixture travels through the preconditioner 15, its temperature rises steadily, then as it travels through the cooking zone, the temperature drops slightly, and the temperature of the mixture drops in the exhaust zone corresponding to the cylinder zone 32, however when As the mixture travels through the forming zone represented by cylinders 34, 36, the temperature increases slightly. As the mixture passes through the die holes 70, the temperature drops further. In this example, about 40% of the mixture will be cooked within preconditioner 16, while the remainder of the cooking will occur as a result of the mixture being heated through extruder 12 at temperatures above about 180°F.

Example 3.

In this example, the initial rice flour mix was prepared from 99.0% by weight long grain rice flour and 1.0% Myvaplexboo surfactant, and this dry mix was fed to a WengerTX equipped with a preconditioner and supply hopper In the -80 twin-screw extruder, hot-boiled rice products are obtained through processing.

The TX-80 extruder is schematically illustrated in Figure 1. The extruder is terminated by a twin-screw oblique cone die head, and the entire extruder has 8 round tube heads or cylinder areas.

A dry initial rice flour mixture (moisture content is 11%) is fed into the preconditioner at a rate of 9.8 pounds per minute and mixed with water fed into the preconditioner at a rate of 1.0 pounds per minute, using pressure At 30 psig, steam introduced at a rate of 0.40 pounds per minute increases the temperature of the water and rice flour mixture in the preconditioner. Mixers with different angles of inclination can be used within the preconditioner to provide a wide range of possible mixture residence times.

The mixer was turned at 150 rpm and adjusted to allow the mixture to dwell in the preconditioner for 1.5 minutes. The mixture exiting the preconditioner had a temperature of about 200°F and a moisture content of 25%.

Afterwards, the mixture is fed through the inlet of the extruder into the cooking zone, and tap water is injected into the mixture at a rate of 1.45 pounds per minute (alternatively, however, hot water at a temperature of 180°F can be introduced to reduce required large volumes of hot steam flow). In addition, steam was introduced into the extruder at a flow rate of 0.66 pounds per minute and a steam pressure of 125 psi. The screw speed of the extruder is 150rpm, and the load of the extruder is 11.2KW. When the screw speed is 150rpm, when there is no mixture in the extruder, the load on the extruder is about 2.2KW. The load increase of the press is about 9.9KW.

The temperature of the mixture traveling in the second, third, fourth and fifth zones of the double cylinders is maintained at 210°F, 260°F, 255°F, and 250°F, respectively. In the cooking zone of the extruder, the moisture content of the flour and water mixture is about 36% by weight. The sixth cylindrical zone includes vents that are evacuated to 10-15 in. Hg. The forming zone of the extruder corresponds to the seventh and eighth barrel zones in which the temperature of the advancing mixture is 209°F and 216°F, respectively.

The rate at which the mixture was passed through the extruder (including the total amount of water added to the preconditioner and extruder) was 12.59 pounds per minute. The pressure in the last cylindrical area adjacent to the die is 50 psi, and the moisture content of the extruded product directly passing through the die is 25% by weight, so the vacuum exhaust will remove 11% of the water content in the extruded product. The total open area of the die is 0.6 inches 2, and the extruded product is cut with a cutter according to the length similar to a grain of rice, and the cut product is advanced to a dryer, where the product is subjected to a temperature of about 205°F. The temperature is heated for 13 minutes, and the final moisture content of the dried extruded product is about 11%, and the obtained product is hydrated in about 7-8 minutes, and presents good product integrity and palatability, without There will be dark and focal spots.

Example 4.

In this example, except that the dry initial rice flour mixture is fed into the preconditioner at 8.311 pounds per minute, and mixed with water entering the preconditioner at 0.834 pounds per minute, the remaining operating steps are essentially As in Example 1. The temperature of the water and rice flour mixture in the preconditioner was increased by injecting steam at a rate of 0.37 pounds per minute with a pressure of 30 psi. The agitator in the preconditioner rotates at 175rpm, and the rotating speed is adjusted so that the mixture stays in the preconditioner for 1.5 minutes. The temperature of the mixture coming out of the preconditioner is about 208°F, and the moisture content is 26.88%.

Then the rice flour and water mixture is sent into the inlet of the extruder located at the inlet of the hot cooking zone, while tap water is added to the mixture at a rate of 0.83 pounds per minute, and steam at 0.59 pounds per minute is also added to the pressure at a rate of 0.59 pounds per minute. The speed is introduced into the mixture located in the hot cooking area of the extruder. The screw of the extruder rotates at a speed of 175rpm. The load of the extruder is 20KW. When there is no mixture, the load on the extruder is about 2.2KW, so when extruding The increased load in the press due to the handling of the mixture is about 17.8KW.

In the cooking zone of the extruder, the temperature of the mixture is maintained at 176°F, 200°F, 200°F and 200°F for the second, third, fourth, and fifth barrel zones, respectively. The moisture content of the rice flour and water mixture in the cooking zone of the extruder was about 36.4%. Apply a negative vacuum pressure of 15 in. Hg. column to the exhaust hole in the sixth cylinder zone. The forming zone of the extruder corresponds to the seventh and eighth barrel zones, and the temperature of the mixture traveling in the eighth barrel zone is about 169°F.

The speed at which the product passes through the extruder (including the total amount of water added to the preconditioner and the extruder) is 10.94 pounds per minute, the pressure in the seventh cylinder zone is 200 psi, and in the last cylinder zone adjacent to the die The pressure is 500psi, and the moisture content of the extruded product directly passing through the mold is 26.75%. The extruded, chopped article proceeds to a dryer at a drying temperature of 125°F for a total drying time of 30 minutes. The final moisture content of the dried article is about 12.53%.

Claims (18)

1. A low-temperature extrusion method for producing quick-boiled noodle products, said method comprising the following steps: (a) Prepare a dough mixture in the preconditioner (15) by mixing flour and water, and raising the temperature of said mixture to a range from about 150°F to 210°F, and allowing said mixture to Hold in the preprocessor (15) for a period of time from about 20 seconds to 3 minutes; (b) introducing said dough mixture into the cylinder (14) of an extruder (12) equipped with two rotatable screws (40) with helical teeth (40) and an extrusion die (18); (c) Turn the screw (40) so that the dough mixture first passes through a cooking zone along the length of the cylinder, and the mixture stays in the cooking zone for 10-25 seconds; zone and deflate the mixture in the degassing zone, before entering the degassing zone, the dough mixture comprises 80-50% by weight of flour and 20-50% of water, and then passes through a forming zone , wherein the dough mixture is held at a temperature of 130°F to about 210°F for 20-60 seconds and subjected to a pressure ranging from about 200Psig to 120Psig; finally passing through said extrusion die (18) to produce an extruded product; (d) drying the extruded product; (e) the maximum temperature of the dough mixture in the cooking zone is up to about 215°F. 2. The method according to claim 1, characterized in that the dough mixture is kept in the extruder cylinder (14) for a residence time of 30 seconds to 85 seconds. 3. The method according to claim 1 or 2, characterized in that the extruder (12) has two intermeshing co-rotating screws (40) and comprises rotating the screws (40) along The steps of feeding the dough mixture sequentially along the length of the cylinder. 4. The method according to claim 1, characterized in that it includes the step of adding steam and water to the flour in the preconditioner (15). 5. The method of claim 1 including the step of subjecting the dough mixture to a vacuum in the degassing zone. 6. The method of claim 5, wherein the vacuum is on the order of about 5 inHg to about 20 inHg. 7. The method of claim 1 wherein said drying step includes the step of subjecting the extruded article to a temperature of from about 75°F to about 180°F for a period of about 20 to about 60 minutes. 8. The method according to claim 1, wherein the drying step continues until the humidity of the dried product reaches a level of about 10%-12% (percentage by weight). 9. The method according to claim 1 or 2, characterized in comprising the step of injecting steam and/or water into the dough mixture while the mixture is fed along the length of the cooking zone. 10. Method according to claim 1 or 2, characterized in that it comprises the step of being subjected to indirect heat exchange during the feeding of the dough mixture along the length of the cylinder (14). 11. The method according to claim 1, characterized in that said step of discharging said gas comprises the step of rotating an exhaust device screw (60) in an exhaust channel (50) communicating with said exhaust area, The exhaust screw (60) has helical teeth that deflect the mixture towards the barrel (14) while allowing moisture to escape through the channel (50). 12. The method according to claim 11, characterized in that said exhaust channel (50) has an area perpendicular to the axis of rotation of said screw (40), which is located in the exhaust area away from said cylinder The direction increases in size to reduce the face velocity of any portion of the mixture flowing through the channel (50), thereby effectively preventing escape of portions of the mixture when the moisture is expelled. 13. The method according to claim 1, characterized in that the mixture reaches the highest temperature it has experienced in the extruder (12) in the cooking zone before moisture is removed therefrom. 14. The method according to claim 1 or 2, characterized in that the residence time of the dough mixture in the preconditioner (15) is from 1 minute to 2 minutes. 15. The method of claim 1 or 2, wherein the pressure in the forming zone is from about 500 Psig to about 600 Psig. 16. The method of claim 1 or 2, wherein the dough mixture comprises about 99.5% by weight semolina. 17. The method according to claim 1 or 2, wherein the dough mixture comprises 0.5% surfactant Myvaplex600 by weight. 18. The method of claim 8, wherein the extruded article is dried at a temperature of about 120°F to about 140°F over a period of about 20 minutes to about 30 minutes.

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