JPH069473B2 - Continuous production method of rice cake - Google Patents

Description

TECHNICAL FIELD The present invention relates to a continuous production method of mochi used for ozoni, Isobeyaki, etc., and more specifically, a continuous production method of said mochi using a twin-screw extruder. Regarding

[Conventional technology]

The conventional method for producing rice cake is to wash the rice cake with water, soak it in water, drain it, steam it for 30 to 60 minutes in a steamer, and then treat it with a rice cake making machine or rice cake kneading machine to make rice cake.

Such a conventional method has the following drawbacks in the case of continuous production.

Since the steaming time is as long as 30 to 60 minutes, the device is larger than the production amount, resulting in poor economy and workability.

The rice cake making machine or rice cake kneading machine has a completely different structure from the steaming machine and requires a separate operation from the steaming machine, and also treats steamed rice at a temperature lower than the steaming temperature, and also makes contact with the outside air. Because it is difficult to avoid, it is susceptible to bacterial and mold contamination.

Similarly, it is extremely difficult to prevent the contamination of bacteria and mold in the process of molding, filling, and packaging rice cakes, and in order to prevent contamination, expensive clean room facilities, advanced microbial control, and the use of oxygen scavengers are required. Is a heavy burden.

[Problems to be solved by the invention]

The object of the present invention is to significantly improve the drawbacks of the conventional method as described above by using a biaxial support extruder, and to compare with the rice cake and texture obtained by the conventional method, texture, elongation, etc. It is to provide a continuous production method of rice cakes, which can obtain rice cakes without rice cake.

[Means for solving problems]

The present invention is characterized in that the hydrated glutinous rice is supplied to a twin-screw extruder having functions of heating, cooling, kneading, shearing, pressurizing and extruding, heated to a high temperature, and then kneaded and sheared while being cooled and extruded from a die. It is a continuous production method of rice cake.

The twin-screw extruder used in the present invention comprises a feeder, a barrel, a twin-screw, a kneading paddle, a die and a screw driving unit, and the barrel has a heating / cooling function, such as heating, cooling, kneading, shearing, and extrusion. This device has the function of (ex: KEX65 type manufactured by Kurimoto).
The details of the production method of the present invention are described below.

The glutinous rice used in this method is hydrated so as to have a required water content by washing with water or immersing in water after rinsing, preferably after immersing in water for 4 hours or more after rinsing.

After washing with water or dipping after washing with water, the rice bran is drained and supplied in a fixed amount from the feeder to the extruder. In order to adjust the water content of the obtained rice cake to 40-47%, water is quantitatively supplied from the water supply port installed immediately after the feeder. Moisture of mochi
The reason for limiting the content to 40 to 47% is that if it is less than 40%, it is hard and poor in elongation and the texture is unfavorable, and if it exceeds 47%, it tends to drip and is too soft.

The glutinous rice and water supplied to the extruder are heated by a progressive screw and heated to 130 ° C or higher to be gelatinized. The heat-gelatinized rice cake is kneaded and sheared at 40-100 ° C.
It is cooled down and extruded from the die.

Here, the selection of the type of screw in the heating / cooling process is extremely important.

The types of screws for the twin-screw extruder include a progressive screw having no kneading or shearing function, a reverse feeding cut screw having a kneading or shearing function, and a kneading paddle.

From the extruder feeder to the maximum heating zone of 130 ° C or higher, it is necessary to use only a progressive screw without kneading and shearing functions. The reason for this is that kneading in a heating process up to 130 ° C or higher and a heating zone of 130 ° C or higher, and inserting a screw with a shearing function makes the rice cake liable to drip, and is particularly unsuitable for simmering. is there.
The reason for limiting the optimum heating temperature to 130 ° C or higher is 130 ° C.
This is because if the amount is less than 1, the residual rice grains are partially observed.
Further, in order to obtain a good rice cake, heating up to about 160 ° C is sufficient, but there is no particular upper limit to the heating temperature as long as it does not cause deterioration such as browning.

On the other hand, in the cooling process from 100 to 40 ° C, it is necessary to give sufficient kneading and shearing in order to obtain a good texture of rice cake in a short time.

As the kneading and shearing means, the reverse feed cut screw, kneading paddle (helical forward feed paddle, helical reverse feed paddle, flood forward feed paddle,
Flood reverse feed paddle, etc.) are used in appropriate combination. The helical progressive paddle is a combination of a plurality of helical paddles that are sequentially fed, and the other paddles are also combined in the same manner. These kneading and shearing reverse feed cut screws and kneading paddles are extremely weak even if they have no or no progressive feed function, so they are used alternately in combination with the progressive feed screw. Kneading these,
The required number of reverse feed cutting screws with shearing function and kneading paddles are properly selected depending on the heating temperature of the glutinous rice and the water content of the rice cake.

For example, when the water content is low, the viscosity is higher and the kneading shearing efficiency is better than when the water content is high, so it is possible to reduce the number of kneading, reverse feed screw having a shearing function, and kneading paddles to be incorporated. If there are many, the number of built-in devices is increased.

Under the conditions of this method, if the ratio (L / D) of the extruder effective length (L) and the extruder diameter (D) is 20, it is possible to process L / D.
It need not be larger than D = 20. Taking the case of L / D = 20 as an example, apply 3 / 5L to the feeder section and the maximum heating section, and the latter half
It is appropriate to cool 2/5 L for kneading and shearing, and the latter half 2/5 L
If you use a screw with kneading and shearing function for about half (1/5 L) of the inside, the moisture content will be 40% by selecting a heating temperature of 130 ° C or more.
~ 47% good rice cake can be made.

The non-glutinous rice is heated, cooled, and kneaded and sheared by an extruder to form rice cake, which continuously comes out from the extruder outlet (die).

It takes less than a few minutes to put rice cake into the rice cake and the production equipment is unified, and the production time is greatly shortened. The physical properties of rice cake are comparable to those of the conventional method. The advantages gained by the invention are enormous.

The rice cake outlet temperature may be 40 to 100 ° C, but especially 8
By keeping the temperature at 0 to 100 ° C, the following great advantages over conventional methods can be obtained.

That is, in the case of packed rice cake, the presence of a few bacteria or less in 1 g of rice cake has little effect on the quality of rice cake, but the mold is extremely proliferative on the surface of the rice cake, and even if only one of them is contaminated, it will eventually occur. Proliferate and lose the mochi's commercial value. Keeping the bacterial contamination of the rice cake in the filling and packaging process to be less than a few pieces per 1g of rice cake can be easily achieved by normal hygiene management of the packaging material and prevention of airborne bacterial contamination by installing an inexpensive clean booth around the packaging machine. .

On the other hand, complete control of mold is extremely difficult. Therefore, the conventional method relies on a highly labor-intensive method such as installation of a sophisticated clean room, hot water immersion bacteria after molding and packaging, and use of an oxygen absorber.

The rice cake of the present invention is heated to 130 ° C. or higher and is virtually sterile until the exit of the extruder. Also, set the rice cake outlet temperature to 80
Keeping the temperature at ~ 100 ° C and filling and molding the rice cake with a baby cheese filling and packaging machine from Kusner, for example, even if there is some mold contamination from the packaging material or air, it will be killed by the heat of the rice cake. It is possible to easily make a microbially safe packed rice cake.

〔Example〕

Example 1 After washing with water, the unpolished rice soaked in water overnight was supplied to a twin-screw extruder (KEX65 type manufactured by Kurimoto Steel Works) at a rate of 300 g / min. Water was supplied at a rate of 40 cc / min from the second barrel water supply port by a metering pump to make the moisture content of the rice cake 43%.

Temperature setting is 1st barrel: room temperature, 2nd barrel: 95-100
℃, the third barrel: 120, 130, 140, 150, 160, 170 ℃ each temperature, the fourth barrel: 100 ℃, the fifth barrel: 90 ℃, die: 9
The temperature was set to 0 ° C. and the maximum temperature was set in the third barrel. The screw rotation speed was 30 rpm or 100 rpm.

Under the above respective conditions, the screw pattern was set as follows to produce a rice cake, and a test was conducted.

(1) Screw pattern: All were forward screws except that a reverse screw was arranged on the outlet side of the fifth barrel.

Maximum temperature 120-170 ℃, rotation speed 30rpm or 100rp
The presence of rice grains was recognized in the rice cake in all cases of m, and the lower the maximum temperature, the greater the proportion of rice grains.

(2) Screw pattern: As shown in FIG. 1, a kneading paddle having kneading and shearing functions for the second and third barrels, that is, a helical progressive feed paddle for the second barrel, and a third barrel.
The reverse helical paddle was installed in the barrel, the reverse feeding screw of the fifth barrel was left as it was, and the forward feeding screw was arranged for the others.

When the maximum temperature was 120 ° C, rice grains remained in the rice cake. Maximum temperature 1
In the case of 30 to 170 ° C, no rice grains were observed, but the rice cake became easily dripping and it became hard in the boiling test (Note 1).

(3) Screw pattern: A kneading paddle having a kneading and shearing function was arranged only in the second barrel or the third barrel, and the others were arranged in the same manner as in FIG.

Also in this case, as in the case of (2) above, residual rice grains were observed or the rice cake was easily drooling, which was unsatisfactory.

(4) Screw pattern: Kneading paddle having kneading and shearing functions on the fourth barrel and the fifth barrel as shown in FIG. 2, that is, the helical progressive feed paddle on the fourth barrel, the fifth barrel
A helical reverse feed paddle is placed on the barrel.

Rice grains were observed at the maximum temperature of 120 ° C, but at 130 to 170 ° C, both the boiling test (Note 1) and the texture test by the oven test (Note 2) were good. Screw rotation speed 30rp
No difference was observed between m and 100 rpm.

(Note 1) Boiling test Put a 50 x 30 x 10 mm rice cake in water and boil for 10 minutes.
Deformation was tested using a commercially available rice cracker made of 100% paddy rice rice as a control.

(Note 2) Oven test 800W that preheated rice cake of 50 × 30 × 10mm size
Was put in a commercial electric oven toaster of No. 3 and heated for 5 minutes, and then tasted, and the texture was tested by using a commercial rice cake using 100% paddy rice rice as a control.

(Note 3) In this example and the following examples, the reverse feeding screw was arranged on the outlet side of the fifth barrel.
This is to make the flow of the processed material uniform at the outlet.

Example 2 After washing with water, soaking was carried out for 4 hours, and drained glutinous rice was supplied to a twin-screw extruder at a rate of 300 g / min, and water was supplied from the second barrel at a rate of 25,35,50,60,70 cc / min. It was supplied, the screw pattern was the same as in FIG. 2, the rotation speed was 40 rpm, and the maximum temperature was 140 ° C. to produce rice cake.

The results of the boiling test and the oven test (texture test) of the obtained rice cake are shown in Table 1.

From the results in Table 1, it can be seen that the moisture content of the rice cake should be in the range of 40 to 47%.

Example 3 Immediately after draining the washed washed rice cake without soaking, 300 g /
Minute and water were quantitatively supplied at a rate of 55 ml / minute. The screw pattern is as shown in Fig. 2 and the screw rotation speed is 60 rpm.
And The highest heating temperature was 140, 150, 160 and 170 ℃, and the rice cake was produced. The resulting mochi has a water content of about 43
%Met.

There were no problems in the boiling test. The oven test showed that the texture was slightly poor at 140 ° C and the texture was slightly brittle. Even at 150 ° C, this tendency remained considerably. 160,1
At 70 ° C, this tendency was slightly observed, but it was within the range of being accepted as a product. No benefit of 170 ° C was observed.

Example 4 Mochi which was washed with water, soaked overnight and drained was supplied at 300 g / min, and water was supplied to the twin-screw extruder at a rate of 40 cc / min so that the moisture content of the mochi was 43%.

The screw pattern is the same as in Fig. 2 and the rotation speed is 60 rpm,
The maximum heating temperature was 140 ° C.

The rice cake for microbiological examination was directly released from the die outlet, filled in a chlorine-sterilized 100 cc polyethylene cup, pre-deposited with aluminum, and heat-sealed with a polyethylene cap. 25 rice cakes are collected every 2 minutes for 25
After left at 3 ° C for 3 weeks, the number of viable bacteria and the presence or absence of mold were observed.

As a result of the microbiological test, no mold was found in any of them.

Regarding the viable cell count, 22 did not show any colonies in the petri dish. The remaining 8 colonies in the petri dish were 1 to 3 and had no bacterial problem.

〔The invention's effect〕

The present invention has remarkable effects as listed below.

(1) In the production of rice cakes that are eaten as simmered rice or rolled in Isobe, the steps of steaming rice cake and attaching rice cakes can be performed with a single machine and within a few minutes.

(2) Despite the fact that the production is extremely simplified, a combination of the extruder screw and the kneading paddle provides the same texture and elongation as the conventional method.

(3) Since the rice cake is heated to 130 ° C or higher, the rice cake is virtually aseptic, and if mold filling and packaging are performed at 80 to 100 ° C, complete control of mold is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a screw pattern of a twin-screw extruder used for comparison, and FIG. 2 is a diagram showing a screw pattern of a twin-screw extruder used in the production method of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Akita 2-3-26 Wakamatsucho, Ishioka City, Ibaraki Prefecture (72) Inventor Takao Tomita 5-24-22 Maesawa, Higashi-Kurume City, Tokyo (72) Inventor Tatsuo Hayashi 2-8-45 Shibaya, Suminoe-ku, Osaka City, Osaka Prefecture Sumiyoshi Plant, Kurimoto Iron Works Co., Ltd. (56) References JP-A-60-227645 (JP, A) JP-A-52-117479 (JP, A)

Claims (3)

[Claims] 1. A biaxial extruder is provided with hydrated glutinous rice, which is conveyed without kneading and shearing using a progressive screw while being heated to 130 ° C. or higher, and then conveyed with kneading and shearing. While being cooled to 40 to 100 ° C., it is extruded to obtain a rice cake having a water content of 40 to 47%. 2. The continuous method for producing rice cake according to claim 1, wherein the cooling temperature is 80 to 100 ° C. 3. The method for continuously producing rice cake according to claim 1, wherein the water-containing unglutinous rice is fed to the twin-screw extruder while water is added.