JP4236382B2 - Method and apparatus for producing dried okara - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for producing dried okara.
[0002]
[Prior art]
Okara is a residue obtained by adding a water-soluble solvent to soybeans or defatted soybeans and separating the extract (soy milk). Moreover, since 90% or more of the carbohydrates are dietary fiber, they are excellent in physiological function.
[0003]
For this reason, the effective use of okara is extremely important from the perspective of the future food balance and environmental conservation.
In Japan, more than 500,000 tons of soybeans are processed into tofu annually, and it is estimated that around 700,000 tons of okara is produced at that time, but 80% is discarded as industrial waste, and the remaining 20% is feed. It is used for breeding and is currently very rarely used as food.
[0004]
Okara has traditionally been used as a side dish, either directly or with vegetables, but in recent years, focusing on its functional characteristics such as water absorption and dispersibility and amino acid composition, bread products, paste products and meat There is a tendency to positively improve quality by adding it to products and the like, and there is a gradual increase in demand for good quality okara.
[0005]
However, since okara is bulky and easily proliferate in a wet state, it has been very difficult to store and handle for a long time.
In addition, if the germs grow too much in okara, not only the water absorption and water retention characteristic of okara are impaired due to acid production or pH reduction, but also pathogens and spoilage odors are generated, which is extremely unsanitary. And could not be used as food.
[0006]
In order to eliminate these points, the dried okara is dried to dry it.
However, because okara is excellent in water absorption and water retention, dehydration and drying are very difficult. For example, it takes a long time to separate an extract (soy milk) and a residue (okara). Although it is squeezed or strongly centrifuged, it is difficult to reduce the water content of the residue from 80% or less.
[0007]
For this reason, if the drying conditions are set strictly in order to dry the okara sufficiently, the water absorption and water retention from okara are impaired, and a burning odor and browning occur. It was.
On the other hand, if the drying conditions are set gently, not only does it take a long time to dry from the okara, but there is a problem that the bacteria propagate during that time.
[0008]
Conventionally, as a method for producing dried okara, for example, after separating okara, hydrogen peroxide is quickly added and the product temperature is raised to 80 ° C or higher to sterilize, and the entire process is made to a product temperature of 120 ° C or lower. A method for producing dried okara with good water absorption and water retention that maintains and dries and suppresses contamination of germs (see Japanese Examined Patent Publication No. 61-3460), forcing the heated okara in a pressure-sealed heating zone A method for producing dried okara that is sterilized by passage and sterilized at a temperature of 120 ° C. or less and has little water browning and has high water absorption (see Japanese Patent Publication No. 2-58907) is proposed.
[0009]
However, since the dried okara produced by the above method is added with hydrogen peroxide for sterilization, it cannot be said that the safety as a food is high considering the influence on the human body and the environment.
Moreover, in said manufacturing method, it is semi-closed circuit drying, and it was difficult to oxidize the to-be-processed object and to perform the odor treatment of the exhaust gas generated at the time of drying.
[0010]
Furthermore, many of the conventional dried okara still have a large number of bacteria, are not safe to use as food or food additives, and are not suitable for long-term storage, so it has been difficult to distribute them to the market.
[0011]
[Problems to be solved by the invention]
The present invention has been made in view of such problems of the prior art, and the object thereof is the quality of raw material okara without discharging the odor generated from the raw material okara to the outside of the drying apparatus. The raw material okara can be sterilized and sterilized while maintaining the quality, and the raw material okara can be uniformly dried, and further provides a method and apparatus for producing dried okara that is energy-saving and low in running cost. is there.
[0012]
[Means for Solving the Problems]
That is, according to the present invention, a drying container for containing raw material okara is provided in the drying chamber, and the raw material okara is provided by heat transfer from the heat medium gas circulated and supplied into the drying chamber while rotating the drying container. A method for producing dried okara from which moisture is removed and sterilized by replacing the air in the drying chamber with water vapor of 90% (volume ratio) or more before the start of drying. 70% to 90% (fixed rate drying period), after drying with atmospheric superheated steam at a steam concentration of 90% (volume ratio) and 120 to 250 ° C., the raw material okara There is provided a method for producing dried okara, characterized in that drying is performed with air having a water vapor concentration of not more than 50% (volume ratio) and not more than 150 ° C. during the final drying period of the residual moisture.
[0013]
At this time, in this invention, it is preferable to make the end point of a fixed rate drying period into the time of rising from 100 degreeC which is the product temperature in a fixed rate drying period, and reaching 101-120 degreeC.
[0014]
Moreover, in this invention, it is preferable to control the pressure in a drying chamber within the range of +/- 0.5kPa with respect to atmospheric pressure.
[0015]
Furthermore, in the present invention, it is preferable that the drying container is a multi-sided cylinder or a cylinder having a lifter on its inner surface, and the raw material okara is dried while the raw material and the hogsi medium are brought into contact with each other.
[0016]
According to the present invention, there is also provided a dry okara manufacturing apparatus for removing moisture from raw materials and sterilizing, wherein the drying chamber forms a predetermined heat medium gas atmosphere by circulating heat medium gas. A drying container accommodated in the drying chamber and containing raw material okara and a hogsi medium, a drying container rotating means for rotating the drying container, and a heating medium gas for replacing air with water vapor as the heating medium gas. a steam supply means for supplying water vapor to a heater for heating the heating medium gas, a circulation fan to circulate the heat medium gas, and the air inlet for introducing air into the drying chamber, the heat of the drying chamber A control unit that adjusts the medium gas atmosphere and adjusts the introduction amount of air at the end of the constant rate drying period from the raw material, and condenses excess water vapor from evaporation of the raw material from the raw material and introduces air in the drying chamber Superheated steam Apparatus for producing dry okara characterized by comprising a condenser for condensing a portion, is provided.
[0017]
At this time, in the present invention, the drying container is preferably a multi-sided cylinder or a cylinder having a lifter on the inner surface, and the hogsi medium has a shape having a plane such as a cube or a triangular pyramid, and one side thereof is 10 to 10 mm. It is preferable that it is 100 mm.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The method for producing dried okara in the present invention will be described.
The main feature of the production method of the present invention is that the period from the start of drying to 70 to 90% of the retained water from the raw material is removed (constant rate drying period), the water vapor concentration is 90% (volume ratio) or more, In addition, after drying with atmospheric superheated steam at 120 to 250 ° C, the final drying period of residual moisture from raw materials is dried with air having a water vapor concentration of 50% (volume ratio) or less and 150 ° C or less. Is to do.
As shown in FIG. 1, this is a fixed rate drying period (a period in which the material temperature is substantially constant and a period in which all the inflow heat into the material is consumed for moisture evaporation) to a reduced rate drying period (a period in which the material temperature rises). By switching from drying with superheated steam to drying with air before and after moving to, the rapid rise in product temperature that occurs after the constant rate drying period can be suppressed. This is because the okara can be dried uniformly without damaging the odor and without causing a burning smell or browning.
[0019]
At this time, in this invention, it is preferable to make the end point of a fixed rate drying period into the time of rising from about 95-100 degreeC which is the product temperature in a fixed rate drying period, and reaching 101-120 degreeC.
This is because it is observed that okara does not brown up to a product temperature of about 110 ° C., although it depends on the time required for the product temperature to rise.
[0020]
In the present invention, it is also important to dry the raw okara in an atmospheric pressure superheated steam atmosphere preferably occupied by 100%, at least 90% or more of steam.
Note that the atmosphere occupied by the normal pressure superheated steam exhibits an “oxygen-free state” because the air partial pressure is almost “zero” and almost no air is present.
In order to maintain such an atmosphere in the dryer under a certain condition and continuously maintain an oxygen-free state, the pressure in the dryer is set to a minute differential pressure (± 0.5 kPa) with respect to atmospheric pressure. It is important to control within the range and continue to introduce or generate superheated steam.
[0021]
Furthermore, in the present invention, it is preferable to perform the superheated steam of the heat medium gas in a closed circuit type.
As a result, there is no inflow of air into the drier or outflow of exhaust gas to the outside of the drier during the drying process, so there is no oxidation of the raw material due to oxygen, and the odor generated from the drier is released to the outside. Since it does not discharge, it can contribute to environmental improvement.
Excess steam (evaporated steam and odor generated from raw material okara) is recovered as condensed treated water by a condenser and subjected to wastewater treatment.
[0022]
Next, in the present invention, the drying container 10 is a multi-faced cylinder (refer to FIG. 2A) or a cylinder having a lifter on the inner surface (refer to FIG. 2B), and the raw material Okara 60 and the hogsi medium 20 are contacted. It is important to dry the raw okara 60 while mixing.
Thereby, since raw material okara can be loosened reliably, the contact area of heat-medium gas and raw material okara can be enlarged, and a uniform and high quality dry okara can be manufactured.
[0023]
Although the drying container 10 used by this invention will not be specifically limited if it is a polyhedron, It is preferable that the cross-sectional shape of a polyhedron is an octahedron and a hexahedron.
Moreover, in the case of a cylinder with a lifter, although it does not specifically limit, It is preferable that the number of the lifters 80 is 2-6.
[0024]
The hog medium 20 used in the present invention has, for example, a shape having a plane such as a cube or a triangular pyramid as shown in FIG. 3, and one side T thereof is 10 to 100 mm (more preferably 10 to 50 mm). Is preferred.
This is because the hogsi medium 20 is a polyhedron, and the unraveling effect is increased by rolling from the top. Further, by making the one side T 10 to 100 mm, excessive crushing is prevented, and This is because it is possible to easily separate from the network.
Moreover, it is preferable that the volume ratio of the raw material okara to a hogsi medium in a dry container is 2-100.
Furthermore, the material of the above-mentioned hogsi medium is not particularly limited as long as compatibility with a dry container and food hygiene are taken into consideration. For example, Teflon (polytetrafluoroethylene), nylon, PE, and PP are preferable. .
[0025]
Here, the drying method using superheated steam is a drying method using steam (dry steam) having a drying capacity equal to or higher than the saturation temperature. Under normal pressure, water vapor is saturated water vapor at less than 100 ° C. and does not have a drying ability. However, when it reaches 100 ° C. or more, it has a drying ability. Become. At the temperature of water vapor, there is a temperature (reversal point temperature) at which the drying rate of superheated steam is higher than that of heated air drying at around 150 ° C to 180 ° C.
That is, the superheated steam is steam that is heated to 100 ° C. or higher (120 to 250 ° C. in the present invention) with saturated steam evaporated at 100 ° C. being kept at normal pressure.
[0026]
The feature of drying with superheated steam is that the interior of the drying chamber can be filled with water vapor, so there is no oxidation from the raw material and no formation of cortex due to hardening of the raw material from the surface, and the product temperature during the majority of the moisture evaporation period. Is maintained at approximately 100 ° C., so that sterilization, sterilization, and enzyme deactivation can be performed up to the inside of the dried material.
[0027]
Hereinafter, based on the drawings, the method and apparatus for producing dried okara of the present invention will be described in more detail.
FIG. 4 is a schematic view showing an example of a production apparatus for dried okara according to the present invention.
The drying oven manufacturing apparatus of the present invention is accommodated in a drying chamber 12 that forms a predetermined heating medium gas atmosphere by a circulating heating medium gas, as shown in FIG. , A drying container 10 for containing raw okara and a hogsi medium, a drying container rotating means 40 for rotating the drying container 10, and a steam for supplying water vapor to the drying chamber 12 to replace air with water vapor as a heat medium gas Supply means 32, a heater 33 for heating the heat medium gas, a circulation fan 37 for circulating the heat medium gas, an air inlet 14 for introducing air into the drying chamber 12, and a heat medium gas in the drying chamber 12 A control unit (not shown) that adjusts the atmosphere and adjusts the amount of air introduced at the end of the constant rate drying period from the raw material, and condensates excess steam accompanying the evaporation of water from the raw material and dries when air is introduced. Room A portion of the superheated steam within 2 is obtained and a condenser 42 to condense.
[0028]
Here, in the drying method in FIG. 4, first, the raw material okara and the hogsi medium are placed in the drying container 10 and accommodated in the drying chamber 12.
Next, after introducing water vapor from the water vapor supply means 32 and performing steam replacement and preheating in the drying chamber 12, the drying container 10 is rotated by the drying container rotating means 40, and as shown in FIG. The heating medium gas of superheated steam (120 to 250 ° C.), which is set and controlled, is dried from a heating medium gas outlet (not shown) disposed in the upper portion of the drying chamber 12 while the 60 and the hogsi medium 20 are contacted and mixed. While being introduced into the chamber 12, the heat medium gas introduction means 35 directly introduces it into the drying container 10 to perform superheated steam drying from the raw material.
Next, at or around the end of the constant rate drying period from the raw material, a part of the superheated steam in the drying chamber 12 is condensed by the condenser 42 and air is introduced into the drying chamber 12 from the air inlet 14. .
By introducing into the drying chamber 12 and the drying container 10 the air-based heat medium gas (water vapor concentration of 50% [volume ratio] or less and 150 ° C. or less) thus controlled, drying from the raw material Continue.
[0029]
In the apparatus of the present invention, the heat medium gas circulation path 36 is provided, and the heat medium gas is circulated in the drying chamber 12 by the circulation fan 37 and the heating medium 33 is controlled by the heater 33. ing.
In the apparatus of the present invention, a high-performance HEPA filter 38 is provided in the air inlet 14 so that dust-free and sterilized air is introduced into the drying chamber 12 at the end of the constant rate drying period from the raw material. It is preferable to attach.
[0030]
Furthermore, in the apparatus of the present invention, it is preferable that the condenser 42 is provided outside the closed circuit system of atmospheric superheated steam, and the closed circuit system and the outside air are continuously communicated via the condenser 42.
That is, in the apparatus of the present invention, when the closed circuit system is at normal pressure, the pressure is adjusted so that there is no pressure difference between the closed circuit system and the condenser 42. When the closed circuit system becomes negative pressure, the closed circuit system is automatically maintained at normal pressure by supplying the outside air to the condenser 42.
At this time, it is preferable to control the fine pressure adjusting damper 39 in conjunction with the pressure sensor so that the pressure in the dryer 12 is a minute differential pressure (± 0.5 kPa) with respect to the atmospheric pressure.
[0031]
【The invention's effect】
As described above, according to the present invention, the odor generated from the raw material okara can be sterilized and sterilized while maintaining the quality of the raw material okara without discharging the odor from the drying apparatus. It is possible to provide a method and an apparatus for producing dried okara that can uniformly dry okara and further save energy and have a low running cost.
[Brief description of the drawings]
FIG. 1 is a graph showing changes in average moisture content and material temperature over time when a sufficiently wet material is dried under steady conditions.
FIGS. 2A to 2B are explanatory views showing a method for producing dried okara according to the present invention.
FIGS. 3A to 3B are schematic perspective views showing a hogsi medium used in the present invention. FIGS.
FIG. 4 is a schematic configuration diagram showing an example of a production apparatus for dried okara according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Drying container, 12 ... Drying chamber, 14 ... Air inlet, 20 ... Hogsi medium, 32 ... Steam supply means, 33 ... Heater, 35 ... Heat medium gas introduction means, 36 ... Heat medium gas circulation path, 37 ... Circulating fan, 38 ... HEPA filter, 39 ... fine pressure adjusting damper, 40 ... drying container rotating means, 42 ... condenser, 43 ... water seal / drainage tank, 60 ... raw material okara, 80 ... lifter.

Claims (7)

In the drying chamber, a drying container for storing the raw material okara is provided, and while the drying container is rotated, the operation of removing moisture from the raw material and sterilization is performed by heat transfer from the heat medium gas circulated and supplied into the drying chamber. A method for producing dried okara, comprising:
Before the start of drying, the air in the drying chamber is replaced with 90% (volume ratio) or more of water vapor, and the period from the start of drying until 70 to 90% of the retained water from the raw material is removed (constant rate drying period) Is 90% (volume ratio) or more, and after drying with atmospheric superheated steam at 120 to 250 ° C., the water content is 50% (volume ratio) or less during the final drying period of residual moisture from raw materials. And drying with air at a temperature of 150 ° C. or lower.   2. The method for producing dried okara according to claim 1, wherein the end point of the constant rate drying period is a time point at which the end point of the constant rate drying period rises from about 100 ° C., which is the product temperature during the constant rate drying period, and reaches 101 to 120 ° C. 3.   The method for producing dried okara according to claim 1 or 2, wherein the pressure in the drying chamber is controlled within a range of ± 0.5 kPa with respect to atmospheric pressure.   The dried okara according to any one of claims 1 to 3, wherein the drying container is a multi-sided cylinder or a cylinder having a lifter on the inner surface, and the raw okara is dried while contacting and mixing the raw okara and the hogsi medium. Manufacturing method. A device for producing dried okara that performs water removal and sterilization operations from raw materials,
A drying chamber for forming a predetermined heat medium gas atmosphere by circulating heat medium gas;
A drying container housed in the drying chamber and containing raw material okara and hogshi medium;
A drying container rotating means for rotating the drying container;
Water vapor supply means for supplying water vapor to the drying chamber in order to replace air with water vapor as a heat medium gas;
A heater for heating the heat medium gas, a circulation fan for circulating the heat medium gas,
An air inlet for introducing air into the drying chamber;
With adjusting the heat medium gas atmosphere in said drying chamber, at the end of the fixed-rate drying period of the raw okara, and a control unit for adjusting the amount of introduced air,
A condenser that condenses a portion of superheated water vapor in the drying chamber when condensing surplus water vapor accompanying evaporation of water from the raw material and introducing air;
An apparatus for producing dried okara, comprising:   The apparatus for producing dried okara according to claim 5, wherein the drying container is a multi-sided cylinder or a cylinder having a lifter on its inner surface.   The apparatus for producing dried okara according to claim 5 or 6, wherein the hogsi medium has a shape having a plane such as a cube or a triangular pyramid, and one side thereof is 10 to 100 mm.

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