Starch gelatinization method and continuous piping type heat treatment device

Abstract

To provide a starch gelatinization method capable of gelatinizing ungelatinized heat gelatinization type starch contained in liquid food, while realizing stable production of the liquid food product and a continuous tube type heat treatment apparatus.SOLUTION: A starch gelatinization method using a continuous tube type heat treatment apparatus 1 for a liquid food containing ungelatinized heated gelatinized starch, wherein the continuous tube type heat treatment apparatus 1 includes a heating section 33 for heating the liquid food, a holding section 34 for holding the food without heating and cooling, and a cooling section 35 for cooling the liquid food, in the heating section 33. the liquid food contacts with a heating medium across a metal tube wall surface, the food and the heat medium exchange heat while flowing in opposite directions to each other, the temperature of the liquid food at the liquid food outlet 333b of the heating section 33 is 75 to 120°C., and the temperature difference of the temperature of the heat medium at the heat medium inlet 331a of the heating section 33 and the temperature of the liquid food at the liquid food outlet 333b of the heating section 33 is 10°C or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for gelatinizing starch in liquid foods and a continuous piping type heat treatment device. [Background technology]

[0002] <Description of Background Art> BACKGROUND ART Conventionally, there have been proposed devices for subjecting fluid products such as beverages and seasonings to heat treatment (see, for example, Patent Document 1).

[0003] <Explanation of Patent Document 1> For example, the product heat treatment device described in Patent Document 1 is configured to be able to continuously perform the heating treatment and the subsequent cooling treatment of the product.

[0004] <Desired Technology-1> Incidentally, when gelatinizing ungelatinized heat-gelatinizable starch contained in liquid foods by heat treatment, it has been proposed to use a product heat treatment device such as that described in Patent Document 1. However, when a liquid food containing ungelatinized heat-gelatinizable starch is heat-treated using a product heat treatment device such as that described in Patent Document 1, the fluidity decreases due to an increase in viscosity associated with gelatinization, making it impossible to maintain a stable flow rate, resulting in temperature unevenness during heat treatment and making stable production difficult, and therefore there is room for improvement. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-29533 Summary of the Invention [Problem to be solved by the invention]

[0006] <Background Technology Issues> Therefore, an object of the present invention is to provide a starch gelatinization method and a continuous piping type heat treatment device that can gelatinize ungelatinized heat-gelatinized starch contained in liquid foods while enabling stable production of liquid foods. [Means for solving the problem]

[0007] <Contents of Claim 1> In order to achieve the above object, the present invention is realized by the following configuration. (1) The present invention provides a method for gelatinizing a liquid food containing ungelatinized heat-gelatinized starch using a continuous piping heat treatment device, the continuous piping heat treatment device comprising a heating section for heating the liquid food, a holding section for holding the liquid food without heating or cooling it, and a cooling section for cooling the liquid food, wherein in the heating section, the liquid food is in contact with a heat transfer medium separated by a metal pipe wall, and the liquid food and the heat transfer medium exchange heat while flowing in opposite directions, the heating section does not have a scraping mechanism, the temperature of the liquid food at the liquid food outlet of the heating section is 75 to 120°C, and the temperature difference between the temperature of the heat transfer medium at the heat transfer medium inlet of the heating section and the temperature of the liquid food at the liquid food outlet of the heating section is 10°C or less.

[0008] <Contents of Claim 2> (2) The present invention is a continuous piping type heat treatment device that gelatinizes ungelatinized heat-gelatinized starch contained in a liquid food, comprising a heating section that heats the liquid food, a holding section that holds the liquid food without heating or cooling it, and a cooling section that cools the liquid food, wherein in the heating section, the liquid food is in contact with a heat transfer medium separated by a metal pipe wall, and the liquid food and the heat transfer medium exchange heat while flowing in opposite directions, and the temperature of the liquid food at the liquid food outlet of the heating section is adjusted to 75 to 120°C, and the temperature difference between the temperature of the heat transfer medium at the heat transfer medium inlet of the heating section and the temperature of the liquid food at the liquid food outlet of the heating section is adjusted to 10°C or less.

[0009] <Contents of Claim 3> (3) In the present invention, in the configuration of (2) above, a first pump is provided upstream of the heating section to send the liquid food into the heating section, and a second pump is provided downstream of the heating section to draw the liquid food from the heating section.

[0010] <Contents of Claim 4> (4) In the present invention, in either of the configurations (2) or (3) above, the heating section is divided into a plurality of divided heating sections, and a static mixer for stirring the liquid food is provided between the plurality of divided heating sections.

[0011] <Contents of Claim 5> (5) The present invention, in any of the configurations (2) to (4) above, comprises a liquid food filling section that fills a container with the finished liquid food, a storage tank that stores the prepared liquid food, and a balance tank that is provided between the storage tank and the heating section and temporarily stores the liquid food supplied from the storage tank, and the balance tank is provided with an agitator that suppresses settling of the heat-gelatinized starch.

[0012] <Contents of Claim 6> (6) In the present invention, in any of the configurations (2) to (5) above, a liquid food return means is provided downstream of the heating section, which is capable of supplying a portion of the liquid food to the liquid food filling section while returning the remainder, or the entirety if the liquid food filling section stops, to the upstream side of the heating section.

[0013] <Contents of Claim 7> (7) In the present invention, in the configuration of (6) above, the liquid food return means is provided with a return destination selection means that can selectively return a portion of the liquid food to the liquid food filling section while returning the remainder, or the entirety if the liquid food filling section stops, to the storage tank or the balance tank.

[0014] <Contents of Claim 8> (8) In the present invention, in the configuration of (6) or (7) above, the liquid food returning means includes a returning liquid food cooling means for cooling the liquid food returned to the upstream side of the heating section. [Effects of the Invention]

[0015] According to the present invention, it is possible to gelatinize ungelatinized heat-gelatinizable starch contained in a liquid food while enabling stable production of the liquid food. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a schematic configuration of a continuous piping type heat treatment apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view of the inside of the heat exchange piping. [Figure 3] FIG. 2 is a block diagram showing the configuration of a heating section. [Figure 4] FIG. 2 is a block diagram showing the configuration of a heating section equipped with a pressure means and a pressure control section. [Figure 5] FIG. 1 is a table showing the evaluation results of various examples. DETAILED DESCRIPTION OF THE INVENTION

[0017] <Description of Embodiments-1> DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same elements are designated by the same reference numerals throughout the description of the embodiments.

[0018] <Configuration of continuous piping type heat treatment device-1> FIG. 1 is a block diagram showing a schematic configuration of a continuous piping type heat treatment apparatus according to one embodiment of the present invention. As shown in FIG. 1, the continuous piping heat treatment device 1 of this embodiment is an apparatus that gelatinizes ungelatinized heat-gelatinizable starch contained in liquid foods (e.g., sauces, dressings, soups, curries, stews, etc.) by heat treatment, and is equipped with a liquid food preparation unit 2 that prepares the liquid food, a liquid food heat treatment unit 3 that gelatinizes ungelatinized heat-gelatinizable starch contained in the liquid food by heat treatment, and a liquid food filling unit 4 that fills the completed liquid food into containers.

[0019] <Configuration of liquid food mixing section-1> The liquid food preparation unit 2 comprises a dissolving tank 21 for dissolving the ingredients of the liquid food, a fine mixer 22 for stirring the ingredients supplied from the dissolving tank 21 to prepare the liquid food, and a storage tank 23 for storing the liquid food prepared by the fine mixer 22. The ingredients of the liquid food include ungelatinized heat-gelatinized starch. As ungelatinized heat-gelatinized starch is prone to settling, a thickener may be added to prevent this settling.

[0020] <Configuration of liquid food heat treatment section-1> The liquid food heat treatment unit 3 comprises a first balance tank 31 for temporarily storing liquid food supplied from the storage tank 23, a first pump 32 for sending the liquid food in the first balance tank 31 downstream, a heating section 33 for heating the liquid food, a holding section 34 for holding the liquid food without heating or cooling it, a cooling section 35 for cooling the liquid food, a second pump 36 for drawing out the liquid food in each of the sections 33 to 35, and a liquid food return means 37 capable of returning the heat-treated liquid food to the upstream side of the heating section 33.

[0021] <Configuration of liquid food heat treatment section-2> The first balancing tank 31 includes a tank body 311 that stores the liquid food, and an agitator 312 that agitates the liquid food in the tank body 311. With this type of first balancing tank 31, it is possible to adjust the amount of liquid food supplied to the heating section 33, while preventing precipitation of heat-gelatinized starch with the agitator 312, thereby suppressing variations in the gelatinized components of the liquid food.

[0022] <Configuration of liquid food heat treatment section-3> Furthermore, a first pump 32 is provided upstream of the heating section 33 to send the liquid food into the heating section 33, and a second pump 36 is provided downstream of the heating section 33 to draw the liquid food from the heating section 33, thereby ensuring that the liquid food, whose viscosity has increased due to gelatinization caused by the heat treatment, flows. In this embodiment, the pressure within each of the sections 33 to 35 is set to 0.5 MPa or less. This not only allows each of the sections 33 to 35 to be constructed using equipment with an upper limit pressure of approximately 1.0 MPa, but also ensures good durability.

[0023] <Configuration of liquid food heat treatment section-4> Heating section 33 and cooling section 35 are configured using heat exchange piping 38 that brings the liquid food and the heat medium into contact with each other across the metal pipe wall surface. As shown in Fig. 2, heat exchange piping 38 includes outer piping 381, multiple inner piping 382 inserted into outer piping 381, and heat medium flow path 383 formed between the inner circumferential surface of outer piping 381 and inner piping 382. By flowing the heat medium through heat medium flow path 383 while flowing the liquid food through the multiple inner piping 382, ​​heat exchange occurs between the heat medium and the liquid food, and the liquid food is heated or cooled.

[0024] <Configuration of liquid food heat treatment section-5> Typically, a scraping mechanism is provided inside the heat exchange piping 38 to allow highly viscous and sticky contents to flow without adhering to the inside of the piping, but this requires disassembly and cleaning of the scraping mechanism, which reduces sanitization capabilities.The heat exchange piping 38 of the heating section 33 and cooling section 35 of the present invention can be produced stably despite not having a scraping mechanism, from the perspective of sanitization capabilities.

[0025] <Configuration of liquid food heat treatment section-6> The heating section 33 is divided into a plurality of divided heating sections 331 to 333. In other words, each of the plurality of divided heating sections 331 to 333 is configured using one heat exchange pipe 38, and the heating section 33 is configured by connecting three heat exchange pipes 38 in series.

[0026] <Configuration of liquid food heat treatment section-7> The heating section 33 may be made of austenitic stainless steel such as SUS304 or SUS316, duplex stainless steel, super stainless steel, titanium alloy, or other non-magnetic metal. From the viewpoint of rust resistance when flowing liquid food with a pH of 5.0 or less, it is preferable to use SUS316, super stainless steel, or titanium alloy, and more preferably super stainless steel or titanium alloy such as SUS312L or UNSN08354.

[0027] <Configuration of liquid food heat treatment section-8> Static mixers 334 for agitating the liquid food are provided between the divided heating sections 331-333 and downstream of the liquid food outlet of heating section 33. Static mixers 334 are stationary mixers with no driving parts, and the liquid food that enters static mixer 334 is agitated sequentially by elements (not shown). With this configuration, even if there is a bias in heat exchange in each of divided heating sections 331-333, the liquid food can be agitated by static mixer 334, thereby suppressing variations in temperature and gelatinization.

[0028] <Configuration of liquid food heat treatment section-9> As shown in Figure 3, each divided heating section 331-333 has liquid food inlets 331a-333a and liquid food outlets 331b-333b, and heat transfer medium inlets 331c-333c and heat transfer medium outlets 331d-333d, with heat transfer medium inlets 331c-333c being located at the end on the liquid food outlets 331b-333b side and heat transfer medium outlets 331d-333d being located at the end on the liquid food inlets 331a-333a side.

[0029] <Configuration of liquid food heat treatment section-10> If the first divided heating section 331 is the most upstream section in the direction of the liquid food flow, the third divided heating section 333 is the most downstream section in the direction of the liquid food flow, and the second divided heating section 332 is the section in between, the liquid food inlet 331a of the first divided heating section 331 is the liquid food inlet of the heating section 33, the liquid food outlet 331b of the first divided heating section 331 is connected to the liquid food inlet 332a of the second divided heating section 332, the liquid food outlet 332b of the second divided heating section 332 is connected to the liquid food inlet 333a of the third divided heating section 333, and the liquid food outlet 333b of the third divided heating section 333 is the liquid food outlet of the heating section 33.

[0030] <Configuration of liquid food heat treatment section-11> In addition, the heat medium inlet 333c of the third divided heating section 333 is the heat medium inlet of the heating section 33, the heat medium outlet 333d of the third divided heating section 333 is connected to the heat medium inlet 332c of the second divided heating section 332, the heat medium outlet 332d of the second divided heating section 332 is connected to the heat medium inlet 331c of the first divided heating section 331, and the heat medium outlet 331d of the first divided heating section 331 is the heat medium outlet of the heating section 33.

[0031] <Configuration of liquid food heat treatment section-12> With this configuration, in the heating section 33, the liquid food and the heat transfer medium flow in opposite directions to each other while exchanging heat, making it possible to efficiently heat the liquid food while suppressing the temperature difference between the liquid food and the heat transfer medium.

[0032] <Configuration of liquid food heat treatment section-13> 4, heating section 33 may be provided with pressurizing means 335 and pressure control section 336 on the upstream side. Pressurizing means 335 may be composed of, for example, a blower 335a and a sterilizing filter 335b, or may be a pipe for injecting the heat-treated product, or may be a cylinder for inactivated gas, ordinary air, or the like. Pressure control section 336 includes control device 336a, on-off valve 336b for opening and closing the flow path from pressurizing means 335 to first divided heating section 331, pressure gauge 336c provided at least upstream of heating section 33, and more preferably pressure gauge 336d provided further downstream of heating section 33.

[0033] <Configuration of liquid food heat treatment section-14> The provision of pressurizing means 335 and pressure control section 336 makes it possible to reliably flow liquid food whose viscosity has increased due to gelatinization caused by heat treatment from heating section 33. Furthermore, by providing pressure gauge 336d downstream of heating section 33, if the value of downstream pressure gauge 336d is below a certain value, pressurizing means 335 can be activated to compensate for pressure loss that occurs in heating section 33 and static mixer 334, and conversely, if the value of downstream pressure gauge 336d is below another certain value, second pump 36 can be activated to draw out liquid food, making it possible to maintain a more stable flow rate, suppress temperature unevenness in heat treatment, and ensure stable production.

[0034] <Configuration of liquid food heat treatment section-15> Holding section 34 is a section for stabilizing the liquid food that has been heated and gelatinized in heating section 33, and holds the liquid food for a predetermined time (e.g., 120 seconds) that is set for each type of liquid food. Holding section 34 of this embodiment has a simple heat retention function, which can suppress temperature changes in the liquid food.

[0035] <Configuration of liquid food heat treatment section-16> Cooling section 35 cools the liquid food to a temperature suitable for filling. Specifically, similar to heating section 33, cooling section 35 is configured using heat exchange piping 38 that brings the liquid food and the heat transfer medium into contact with each other across the metal pipe wall surface.

[0036] <Configuration of liquid food heat treatment section-17> The liquid food return means 37 comprises a liquid food return passage 371, a first directional control valve 372, a second directional control valve 373, and a return liquid food cooling means 374. The liquid food return passage 371 branches off from the liquid food passage between the holding section 34 and the cooling section 35 and returns the liquid food to the upstream side of the heating section 33. The first directional control valve 372 is provided upstream on the liquid food return passage 371 and switches between a state in which the liquid food is allowed to flow to the cooling section 35 and a state in which the liquid food is returned to the upstream side of the heating section 33. The second directional control valve 373 is provided downstream on the liquid food return passage 371 and switches between a state in which the liquid food is returned to the storage tank 23 and a state in which the liquid food is returned to the first balance tank 31. The return liquid food cooling means 374 is provided on the liquid food return passage 371 and cools the return liquid food.

[0037] <Configuration of liquid food heat treatment section-18> Such liquid food return means 37 allows a portion of the liquid food heated in the heating section 33 to be supplied to the liquid food filling section 4, while the excess heated liquid food residue that cannot be processed in the liquid food filling section 4, or, if the liquid food filling section 4 stops, all of the heated liquid food, can be returned upstream of the heating section 33.Therefore, if processing stagnates downstream of the liquid food heat treatment section 3, the liquid food can be circulated through the liquid food return path 371, thereby continuing the flow of liquid food in the heating section 33 and preventing inconveniences that may arise from stagnation of liquid food (e.g., insufficient swelling, heat breakdown of starch granules, deterioration of flavor, burning, etc.). Furthermore, while supplying a portion of the heated liquid food to the liquid food filling section 4 side, the excess remaining heated liquid food that cannot be processed by the liquid food filling section 4, or if the liquid food filling section 4 side stops, all of the heated liquid food, can be selectively returned to the storage tank 23 or the first balance tank 31, making it possible to select an appropriate return destination depending on the amount of returned liquid food, etc. Furthermore, the provision of returned liquid food cooling means 374 for cooling the returned liquid food prevents the temperature of the liquid food upstream of the heating section 33 from fluctuating greatly depending on the returned liquid food.

[0038] <Configuration of liquid food filling section-1> The liquid food filling section 4 includes a second balance tank 41 for temporarily storing the liquid food supplied from the liquid food heat treatment section 3, a filling machine 42 for filling the liquid food into containers, and a third pump 43 for sending the liquid food in the second balance tank 41 to the filling machine 42.

[0039] <Explanation of starch gelatinization method-1> When gelatinizing ungelatinized heat-gelatinizable starch contained in a liquid food using the continuous piping heat treatment device 1 configured as described above, the temperature of the liquid food at the liquid food outlet of heating section 33 is adjusted to 75 to 120°C, and the temperature difference between the temperature of the heat medium at the heat medium inlet of heating section 33 and the temperature of the liquid food at the liquid food outlet of heating section 33 is adjusted to 10°C or less. In this way, the ungelatinized heat-gelatinizable starch contained in the liquid food can be gelatinized while suppressing problems that may arise due to temperature differences in the liquid food (e.g., insufficient swelling, thermal collapse of starch granules, deterioration of flavor, etc.). Furthermore, 75 to 120°C includes not only the temperature range required for gelatinization of heat-gelatinizable starch (e.g., 90 to 95°C) but also the temperature range required for sterilization of liquid foods (e.g., 75 to 120°C), and therefore the liquid food can be sterilized simultaneously with the gelatinization of the heat-gelatinizable starch. Furthermore, in heating section 33, heat exchange occurs while the liquid food and the heating medium flow in opposite directions, so that the temperature difference between the liquid food and the heating medium can be reduced throughout the entire heating section 33.

[0040] <Liquid Food Description> The liquid food of the present invention will be described in detail below.

[0041] <pH of liquid foods> The pH of the liquid food is 5.5 or less, preferably 5.3 or less, and more preferably 5.1 or less. If the pH of the liquid food is within the above range, the microbial growth in the acidic liquid food can be controlled to improve the shelf life, while the flavor of the liquid food can be well balanced. The pH value of the acidic liquid food is measured using a pH meter (tabletop pH meter F-72 manufactured by HORIBA, Ltd.) at 1 atmosphere and a product temperature of 20°C.

[0042] <Explanation of heat-gelatinized starch in liquid foods - 1> Starch is classified into heat-gelatinizable starch and cold-water swelling starch, and the present invention uses heat-gelatinizable starch. Heat-gelatinizable starch is starch that gelatinizes when added to water and heated at high temperatures, more specifically, for example, at about 70°C or higher, and absorbs water to swell and become viscous. On the other hand, cold-water swelling starch is starch that retains the properties of its gelatinized state, and swells and becomes viscous in water at room temperature (20°C) without the need for heating. The present invention aims to provide a starch gelatinization method and continuous piping heat treatment device that can efficiently gelatinize ungelatinized heat-gelatinizable starch contained in liquid foods.

[0043] <Explanation of heat-gelatinized starch in liquid foods - 2> Examples of heat-gelatinizable starches include natural starches and modified starches, and the present invention uses modified starches. Examples of natural starches include corn starch, tapioca starch, wheat starch, and potato starch. Examples of modified starches include those obtained by processing these natural starches. More specifically, examples of modified starches include acetylated adipic acid cross-linked starch, acetylated phosphate cross-linked starch, acetylated oxidized starch, phosphated starch, phosphate cross-linked starch, oxidized starch, acetate starch, hydroxypropyl starch, hydroxypropylated phosphate cross-linked starch, and heat-moisture treated starch. These may be used alone or in combination of two or more.

[0044] <The amount of heat-gelatinized starch contained in liquid foods> The content of heat-gelatinizable starch in the liquid food is preferably 0.5% by mass or more and 4.5% by mass or less of the total liquid food. The lower limit of the content of heat-gelatinizable starch contained in the liquid food is preferably 1% by mass or more, more preferably 1.5% by mass or more. The upper limit of the content of heat-gelatinizable starch contained in the liquid food is preferably 4% by mass or less, more preferably 3.5% by mass or less. If the content of heat-gelatinizable starch is within the above range, syneresis and a decrease in viscosity after long-term storage of the liquid food can be prevented while improving the production suitability of the liquid food through efficient gelatinization.

[0045] <Viscosity of liquid foods before heat treatment> The lower limit of the viscosity indicated by the rotor reading of the liquid food before heat treatment can be 100 mPa·s or more at 20°C, preferably 200 mPa·s or more, and more preferably 300 mPa·s or more. The upper limit of the viscosity of the liquid food before heat treatment can be 2,000 mPa·s or less, more preferably 1,500 mPa·s or less, and even more preferably 1,000 mPa·s or less. In this case, the lower limit of the viscosity η (at 20°C when the temperature rises at D = 30 [1 / s]) calculated from the shear rate and stress of the liquid food before heat treatment can be 39 [mPa·s] or more, preferably 57 [mPa·s] or more, and more preferably 75 [mPa·s] or more.The upper limit of the viscosity η (at 20°C when the temperature rises at D = 30 [1 / s]) calculated from the shear rate and stress of the liquid food before heat treatment can be 380 [mPa·s] or less, preferably 290 [mPa·s] or less, and more preferably 200 [mPa·s] or less. When the viscosity of a liquid food before heat treatment indicated by the rotor reading is about 1,000 mPa·s, the viscosity η calculated from the shear rate and stress (at 20°C when the temperature rises at D=30[1 / s]) is about 200[mPa·s].

[0046] <Viscosity of the resulting liquid food> The lower limit of the viscosity, as indicated by the rotor reading, of a liquid food obtained by gelatinization through heat treatment can be 2,500 mPa·s or more at 20°C, preferably 5,000 mPa·s or more, and more preferably 8,000 mPa·s or more. The upper limit of the viscosity, as indicated by the rotor reading, of a liquid food obtained by gelatinization through heat treatment can be 100,000 mPa·s or less, more preferably 60,000 mPa·s or less, and even more preferably 50,000 mPa·s or less. In this case, the lower limit of the viscosity η (at 40°C when the temperature is decreased at D = 30 [1 / s]) calculated from the shear rate and stress after sterilization of the liquid food obtained by gelatinization through heat treatment is preferably 270 [mPa·s] or more, preferably 400 [mPa·s] or more, and more preferably 540 [mPa·s] or more. Furthermore, the upper limit of the viscosity η (at 40°C when the temperature is decreased at D = 30 [1 / s]) calculated from the shear rate and stress after sterilization of the liquid food obtained by gelatinization through heat treatment is 10,800 [mPa·s] or less, preferably 6,480 [mPa·s] or less, and more preferably 4,000 [mPa·s] or less. When the viscosity indicated by the rotor of a liquid food obtained by gelatinization through heat treatment is approximately 5,000 mPa·s, the viscosity η calculated from the shear rate and stress (at 40°C when the temperature is decreased at D=30[1 / s]) is approximately 540[mPa·s].

[0047] <Measurement of viscosity indicated by rotor reading> The viscosity indicated by the rotor reading for liquid foods was measured using a BL-type viscometer at a product temperature of 20°C and a rotation speed of 6 rpm. For viscosity less than 1,000 mPa·s, rotor No. 1 was used; for viscosity between 1,000 mPa·s and 5,000 mPa·s, rotor No. 2; for viscosity between 5,000 mPa·s and 20,000 mPa·s, rotor No. 3; and for viscosity between 20,000 mPa·s and 100,000 mPa·s, rotor No. 4 was used. The value was calculated from the reading 3 minutes after the start of measurement. For viscosity of 100,000 mPa·s or more, a BH type viscometer is used, with a product temperature of 20°C and a rotation speed of 2 rpm. For viscosity of less than 500,000 mPa·s, rotor No. 6 is used, and for viscosity of 500,000 mPa·s or more, rotor No. 7 is used. The values ​​are calculated from the reading 3 minutes after the start of measurement, with the product temperature at 20°C and a rotation speed of 2 rpm.

[0048] <Measurement of viscosity η calculated from shear rate and stress> The viscosity η calculated from the shear rate and stress of a liquid food before heat treatment (at 20°C when the temperature rises at D = 30 [1 / s]), and the viscosity η calculated from the shear rate and stress of a liquid food obtained by gelatinization through heat treatment (at 40°C when the temperature falls at D = 30 [1 / s]) can be measured using a standard method using a thermostatic bath, a viscometer capable of measuring stress equipped with a cone rotor, etc., and data analysis software. Specifically, using an R-type viscometer, Model RE215R, manufactured by Toki Sangyo Co., Ltd., the viscosity η of liquid foods before heat treatment was measured, calculated from the shear rate and stress at a temperature rise of 20°C in a thermostatic bath, and the viscosity η of liquid foods obtained by gelatinization through heat treatment was measured after gelatinization and swelling, calculated from the shear rate and stress at a temperature fall of 40°C in a thermostatic bath.

[0049] <Flow rate of heat transfer medium and flow rate of liquid food in the heat transfer medium flow path of the heating section> A fast flow rate of the heat medium in the heat medium flow path in the heating section is preferable because the temperature of the heat medium is maintained high, but a slow flow rate will absorb heat from the liquid food and the outside air, causing the temperature of the heat medium to drop and resulting in insufficient swelling. Also, if the flow rate of the liquid food in the heat medium flow path in the heating section is fast, the time of contact with the heat medium will be short, resulting in insufficient heating and insufficient swelling. Conversely, if the flow rate is slow, the liquid food will remain in the metal piping for a long time and will be in contact with the heat medium for a long time, resulting in deterioration of the flavor of the liquid food and burning. Since the heat transfer medium flow rate in the heat transfer medium flow path of the heating section and the effect that the flow rate of the liquid food in the heat transfer medium flow path of the heating section has on the liquid food are inversely proportional, if the heat transfer medium flow rate in the heat transfer medium flow path of the heating section / flow rate of the liquid food in the heat transfer medium flow path of the heating section is 9.5 or higher, inconveniences such as insufficient swelling of the liquid food, deterioration in flavor, and burning can be suppressed.

[0050] <Salt content of liquid foods> The salt content of the liquid food is 0.5% by mass or more of the total liquid food, preferably 1% by mass or more, and more preferably 3% by mass or more. If the salt content of the liquid food is within the above range, the flavor balance of the liquid food can be well balanced.

[0051] <Measurement of salt content in liquid foods> The salt (NaCl) content of liquid foods can be measured using existing official methods. For example, for foods known to contain little other chlorides, the salt equivalent can be calculated from the amount of chloride ions measured using potentiometric titration, Mohr's method, etc. For foods known to contain little other sodium salts, the salt equivalent can be calculated from the amount of sodium measured using ion electrode method, atomic absorption spectrometry, etc.

[0052] <Protein content of liquid foods> The protein content of the liquid food is 2.0% by mass or less of the total liquid food excluding ingredients. If the protein content is higher than this range, there is a risk that the liquid food will burn in the heating section 33.

[0053] <Measurement of protein content in liquid foods> The protein content of liquid foods can be measured using existing official methods. For example, it can be easily measured based on the nitrogen quantification method commonly known as the Kjeldahl method, which is disclosed in "Methods for Analyzing Nutritional Components, etc. in the Nutrition Labeling Standards" (Eishin No. 13, April 26, 1999). Protein in the present invention includes not only high molecular weight compounds, but also amino acids, peptides, etc. If the liquid food contains ingredients, the food should be passed through a 5-mesh (3.033 mm opening) sieve and allowed to flow naturally. [Example]

[0054] The present invention will be described in detail below with reference to an embodiment shown in FIG.

[0055] <Evaluation method> In the table shown in FIG. 5, the meanings of the various symbols are as follows: 〇: A state in which the liquid food after heating has gelatinized the ungelatinized heat-gelatinized starch without any problems such as insufficient swelling, thermal collapse of starch granules, deterioration of flavor, or burning. ×: The liquid food after heating has problems such as insufficient swelling and thermal collapse of starch granules, and the ungelatinized heat-gelatinized starch is not sufficiently gelatinized, or the ungelatinized heat-gelatinized starch is gelatinized but has problems such as deterioration in flavor and burning.

[0056] The inventors of the present application evaluated various examples, and the results are shown in Figure 5. Furthermore, the inventors also evaluated comparative examples, and the results are shown in Figure 5.

[0057] <Effect of the embodiment-1> The effects of the above-described embodiment will be described. The starch gelatinization method of the embodiment is a starch gelatinization method using a continuous piping heat treatment device 1 for a liquid food containing ungelatinized heat-gelatinized starch. The continuous piping heat treatment device 1 is equipped with a heating section 33 for heating the liquid food, a holding section 34 for holding the liquid food without heating or cooling, and a cooling section 35 for cooling the liquid food. In the heating section 33, the liquid food is in contact with the heat transfer medium separated by the metal pipe wall, and heat exchange occurs as the liquid food and the heat transfer medium flow in opposite directions. The temperature of the liquid food at the liquid food outlet of the heating section 33 is 75 to 120°C, and the temperature difference between the temperature of the heat transfer medium at the heat transfer medium inlet of the heating section 33 and the temperature of the liquid food at the liquid food outlet of the heating section 33 is 10°C or less. Therefore, the ungelatinized heat-gelatinized starch contained in the liquid food can be gelatinized while minimizing inconveniences that may arise from temperature differences in the liquid food (Examples 1 to 12). Conversely, when the temperature difference between the temperature of the heat medium at the heat medium inlet of heating section 33 and the temperature of the liquid food at the liquid food outlet of heating section 33 was 10°C or more, the starch granules were thermally disintegrated, and the ungelatinized heat-gelatinizable starch could not be sufficiently gelatinized (Comparative Examples 1 and 2). Furthermore, when the ratio of the heat medium flow rate in the heat medium flow path of the heating section to the flow rate of the liquid food in the heat medium flow path of the heating section was less than 9.5, the thermal energy of the heat medium could not be sufficiently transferred to the entire liquid food, and heat was absorbed by the liquid food and the outside air, causing a drop in the temperature of the heat medium and resulting in insufficient swelling of the liquid food, or localized overheating of the liquid food, resulting in portions of the liquid food that deteriorated in flavor, resulting in burnt portions where the starch was excessively gelatinized in some areas of the ungelatinized heat-gelatinizable starch that was not sufficiently gelatinized (Comparative Example 3).

[0058] <Effect of the embodiment-2> In addition, a first pump 32 is provided upstream of the heating section 33 to send the liquid food into the heating section 33, and a second pump 36 is provided downstream of the heating section 32, holding section 34 and cooling section 35 to draw the liquid food from the heating section 33, holding section 34 and cooling section 35, so that the liquid food whose viscosity has increased due to gelatinization caused by the heat treatment can be reliably made to flow.

[0059] <Effect-3 of the embodiment> Furthermore, the heating section 33 is divided into a plurality of divided heating sections 331 to 333, and static mixers 334 for stirring the liquid food are provided between the divided heating sections 331 to 333. Therefore, even if there is a bias in the heat exchange in each divided heating section 331 to 333, the food can be stirred by the static mixer 334, thereby suppressing variations in temperature and gelatinization.

[0060] <Effect-4 of the embodiment> The food processing system also includes a storage tank 23 for storing the prepared liquid food, and a first balance tank 31 that is provided between the storage tank 23 and the heating section 33 and temporarily stores the liquid food supplied from the storage tank 23. The first balance tank 31 is provided with an agitator 312 that suppresses the settling of heat-gelatinized starch, so that the amount of liquid food supplied to the heating section 33 can be adjusted while the agitator 312 prevents the settling of heat-gelatinized starch, thereby suppressing variation in the gelatinized components of the liquid food.

[0061] <Effect-5 of the embodiment> In addition, a liquid food return means 37 is provided downstream of the heating section 33, which is capable of returning the liquid food to the upstream side of the heating section 33.Therefore, if processing stagnates downstream of the liquid food heat treatment section 3, the liquid food can be circulated through the liquid food return path 371, thereby continuing the flow of liquid food in the heating section 33 and preventing inconveniences that may arise due to stagnation of the liquid food.

[0062] <Effect-6 of the embodiment> In addition, the liquid food return means 37 is equipped with a second directional control valve 373 that can selectively return the liquid food to the storage tank 23 or the first balance tank 31, so that an appropriate return destination can be selected depending on the amount of liquid food to be returned, etc.

[0063] <Effect-7 of the embodiment> In addition, the liquid food returning means 37 is equipped with a returning liquid food cooling means 374 for cooling the liquid food being returned upstream of the heating section 33, thereby preventing the temperature of the liquid food upstream of the heating section 33 from fluctuating significantly depending on the returning liquid food.

[0064] Although the present invention has been described above using embodiments and examples, it goes without saying that the technical scope of the present invention is not limited to the scope described in the above embodiments and examples. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments and examples. Furthermore, it is clear from the claims that forms incorporating such modifications or improvements can also be included within the technical scope of the present invention. [Explanation of symbols]

[0065] 1. Continuous piping type heat treatment device 2 Liquid Food Mixing Department 21 Dissolving Tank 22 Fine Mixer 23 Storage Tank 3. Liquid food heat treatment section 31 First Balance Tank (Balance Tank) 311 Tank body 312 Mixer 32 First Pump 33 Heating Section 331 First divided heating section 331a Liquid food entrance 331b Liquid food outlet 331c Heat medium inlet 331d Heat medium outlet 332 Second divided heating section 332a Liquid food inlet 332b Liquid food outlet 332c Heat medium inlet 332d Heat medium outlet 333 Third divided heating section 333a Liquid food inlet 333b Liquid food outlet 333c Heat medium inlet 333d Heat medium outlet 334 Static Mixer 335 Pressurizing means 335a Blower 335b Antibacterial filter 336 Pressure control section 336a Control device 336b On-off valve 336c Pressure Gauge 336d pressure gauge 34 Retention Section 35 Cooling Section 36 Second Pump 37 Liquid food return means 371 Liquid food return channel 372 First directional control valve 373 Second directional control valve (return destination selection means) 374 Cooling means for reconstituted liquid food 38 Heat exchange piping 381 External piping 382 Internal piping 383 Heat Transfer Medium Flow Path 4 Liquid food filling section 41 Second balance tank 42 Filling machine 43 Third Pump

Claims

1. 1. A method for gelatinizing a liquid food containing ungelatinized heat-gelatinized starch using a continuous piping heat treatment device, comprising: The continuous piping type heat treatment device comprises: a heating section for heating the liquid food product; a holding section for holding the liquid food without heating or cooling it; a cooling section for cooling the liquid food product; In the heating section, the liquid food is in contact with the heat transfer medium across a metal pipe wall, and the liquid food and the heat transfer medium flow in opposite directions to each other to exchange heat, the heating section does not have a scraping mechanism; The temperature of the liquid food at the liquid food outlet of the heating section is 75 to 120°C, the temperature difference between the temperature of the heat medium at the heat medium inlet of the heating section and the temperature of the liquid food at the liquid food outlet of the heating section is 10°C or less; a heat transfer medium flow rate, which is the flow rate at which the heat transfer medium flows through the heating section, divided by a heat transfer medium flow rate, which is the flow rate at which the liquid food flows through the heating section, is 9.5 or more.

2. A continuous piping type heat treatment device for gelatinizing ungelatinized heat gelatinizable starch contained in a liquid food, comprising: a heating section for heating the liquid food product; a holding section for holding the liquid food without heating or cooling it; a cooling section for cooling the liquid food product; In the heating section, the liquid food is in contact with the heat transfer medium across a metal pipe wall, and the liquid food and the heat transfer medium flow in opposite directions to each other to exchange heat, The temperature of the liquid food at the liquid food outlet of the heating section is 75 to 120°C, The temperature difference between the temperature of the heat medium at the heat medium inlet of the heating section and the temperature of the liquid food at the liquid food outlet of the heating section is adjusted to 10°C or less, A continuous piping type heat treatment device, wherein the value obtained by dividing the heat medium flow rate, which is the flow rate at which the heat medium flows through the heating section, by the heat medium flow rate, which is the flow rate at which the liquid food flows through the heating section, is 9.5 or more.

3. a first pump is provided upstream of the heating section to pump the liquid food into the heating section; 3. The continuous piping type heat treatment device according to claim 2, further comprising a second pump provided downstream of the heating section for drawing the liquid food from the heating section.

4. The heating section is divided into a plurality of divided heating sections, 4. The continuous piping type heat treatment device according to claim 2, wherein a static mixer for stirring the liquid food is provided between the plurality of divided heating sections.

5. a liquid food filling section that fills the completed liquid food into containers; a storage tank for storing the prepared liquid food; a balance tank provided between the storage tank and the heating section for temporarily storing the liquid food supplied from the storage tank; The continuous piping type heat treatment device according to any one of claims 2 to 4, wherein the balance tank is provided with an agitator that suppresses precipitation of the heat-gelatinized starch.

6. 6. A continuous piping type heat treatment device as described in claim 5, wherein a liquid food return means is provided downstream of the heating section, which is capable of supplying a portion of the liquid food to the liquid food filling section while returning the remainder, or the entire liquid food if the liquid food filling section stops, to the upstream side of the heating section.

7. 7. The continuous piping type heat treatment device according to claim 6, wherein the liquid food return means is provided with a return destination selection means that can selectively return a portion of the liquid food to the storage tank or the balance tank while supplying the remainder to the liquid food filling section, or the entire liquid food if the liquid food filling section stops.

8. 8. The continuous piping type heat treatment apparatus according to claim 6, wherein the liquid food returning means comprises a returning liquid food cooling means for cooling the liquid food returned to the upstream side of the heating section.

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