JP4556181B2 - Method for producing fermented milk powder by vacuum spray drying - Google Patents

Description

  The present invention relates to a method for producing fermented milk powder by spray-drying fermented milk (for example, fermented milk beverages such as sugar-free drink yogurt and yogurt) under reduced pressure, and in particular, fermenting containing live lactic acid bacteria The present invention relates to a method for producing fermented milk powder suitable for producing milk powder.

 One of the methods for keeping ingredients in food for a long period of time is a drying technique. By drying, the water content in the food can be reduced, and the food can be prevented from being spoiled or changed. Moreover, weight reduction is achieved by drying, and the cost in terms of distribution can be reduced. Therefore, if this drying technique is successfully utilized, there is a possibility that the active ingredients in the food can be retained for a longer period of time.

 Among the foods, there are spray drying, freeze drying, and vacuum spray drying as techniques for drying liquid foods.

Spray drying (hereinafter sometimes referred to as “SD method”) is a method in which a raw material is sprayed from a nozzle under a normal pressure (about 1.0 × 10 ⁵ Pa) to be atomized. This is a method of directly obtaining a dry powder by applying hot air of from ℃ to 200 ℃.

 The freeze drying method (hereinafter sometimes referred to as “FD method”) is a method of dehydrating a liquid material under vacuum conditions by sublimation to obtain a powder. The raw material is rapidly frozen and frozen. After that, drying is performed by reducing the pressure in the drying chamber to sublimate moisture.

 Since the FD method can be dried at a low temperature, it is easy to maintain the activity of useful components that are vulnerable to heat, and there is little change in the components in the food, but the manufacturing cost is high and moisture cannot be evaporated in a short time. There is a disadvantage that it takes a long time to dry, and the powder can be obtained only in a batch system rather than a continuous system.

 On the other hand, the SD method is said to have little component change because it is dried instantaneously, but because it uses hot air (120 ° C to 200 ° C), it is very sensitive to heat (vitamins, useful microorganisms, enzymes Etc.) cannot be denied. However, in the SD method, moisture can be evaporated in a shorter time, powder can be obtained continuously, and drying at low cost is possible.

  Vacuum spray drying (hereinafter sometimes referred to as “VSD method”) is a method of spraying a liquid material in the form of a mist into warm air (approximately 40 ° C.) under reduced pressure conditions. To get. Since this VSD method uses hot air of about 40 ° C., it is possible to obtain a powder in a continuous manner while maintaining the activity of useful components that are weak against heat. That is, the VSD method has the advantages of the two drying methods described above.

In this VSD method, at least a part of the peripheral wall of the evaporation chamber (drying chamber) of the spray drying device is a far infrared radiation surface as a heat source for supplying latent heat at the time of evaporation, and it is altered by heat like milk under reduced pressure. There has also been a proposal of obtaining a powder by drying an easy solution or suspension (Patent Document 1).
JP-A-10-28568

  Among active ingredients in foods, there is a lactic acid bacterium that is considered to have an intestinal regulating action and the like as being weak against heat. Lactic acid bacteria are generally non-spores and are very susceptible to heat because they have an optimum growth temperature of around 37-38 ° C. Even in the conventional VSD method described above, a method for pulverizing foods containing lactic acid bacteria has been proposed. There wasn't. In addition, it has been conventionally proposed to produce live bacterial powder of lactic acid bacteria by the FD method, but there is a problem that the production cost is high as described above.

  In the present specification, claims and drawings, lactic acid bacteria include bifidobacteria and the like in addition to lactic acid bacteria themselves.

  Foods containing lactic acid bacteria are called probiotic foods (for example, lactic acid bacteria beverages and plain yogurt), but probiotics are "living microorganisms" that have the effect of improving the balance of the intestinal flora (bacteria flora). It is said that probiotic foods have various effects in addition to the intestinal regulating effect.

  If this probiotic food (for example, lactic acid bacteria beverage or plain yogurt) can be powdered at low cost and in large quantities, it will be possible to commercialize tablets and granules containing lactic acid bacteria as probiotics. . Moreover, room temperature transportation and room temperature control of lactic acid bacteria used in the factory are possible.

  The present invention relates to a method for producing a fermented milk powder suitable for drying and pulverizing a food (for example, fermented milk) containing lactic acid bacteria as probiotics, in particular, fermented milk powder containing live lactic acid bacteria. It aims at proposing the powdering method of fermented milk suitable for manufacturing.

In order to achieve the above object, the method for producing fermented milk powder by the reduced-pressure spray drying method proposed by the present invention sprays fermented milk to be powdered into a drying tower under reduced pressure , and has a drying temperature of 35 to 38. by vacuum spray drying at ° C., living lactic acid bacteria to a method for producing a fermented milk powder by fermented milk powder you produce vacuum spray drying method comprising, it is adjusted to a temperature corresponding to the temperature in the drying tower Far-infrared rays generated from a heat source for drying disposed in the internal space of the drying tower as means for supplying latent heat for spraying the fermented milk in the drying tower and evaporating the sprayed fermented milk it is shall be used. Further, this case is 70% to 80% of the number of lactic acid bacteria in fermented milk before the number of live lactic acid bacteria of fermented milk powder is carried out under reduced pressure spray drying process.

  According to the present invention, fermented milk powder containing live lactic acid bacteria can be produced from a food (for example, fermented milk) containing lactic acid bacteria as probiotics.

  According to this invention, food (for example, fermented milk) containing lactic acid bacteria as probiotics can be dried and powdered in large quantities at low cost.

  Moreover, according to this invention, 70 to 80% of the number of lactic acid bacteria in fermented milk before performing a reduced pressure spray-drying process can be maintained in fermented milk powder.

  According to the present invention, fermented milk can be powdered in a large amount at low cost, and tablets and granules containing lactic acid bacteria as probiotics can be commercialized. Moreover, room temperature transportation and room temperature control of lactic acid bacteria used in the factory are possible.

  The present invention is a method for producing fermented milk powder by a reduced pressure spray drying method for producing fermented milk powder containing live lactic acid bacteria by subjecting fermented milk to spray drying under reduced pressure.

  That is, the inventors of the present application can produce a fermented milk powder containing live lactic acid bacteria by pulverizing food (eg, fermented milk) containing lactic acid bacteria as probiotics by a reduced pressure spray drying method. It has been found that this is possible, and the present invention has been completed.

  In the above, far-infrared rays can be used as a heat source for drying when fermented milk (for example, fermented milk drink such as sugar-free drink yogurt or yogurt) is spray-dried under reduced pressure.

  According to the inventors' experiments, even in a drying tower (drying chamber) under reduced pressure, if far infrared rays are used as a heat source for drying, heat can be effectively transferred, and living lactic acid bacteria The fermented milk powder containing live lactic acid bacteria could be produced by vacuum spray drying.

  That is, in the method for producing fermented milk powder by the reduced pressure spray drying method of the present invention, the number of live lactic acid bacteria in the fermented milk powder is 70% to 80% of the number of lactic acid bacteria in the fermented milk before performing the reduced pressure spray drying treatment. It is characterized by being.

  Thus, in the method for producing fermented milk powder by the reduced pressure spray drying method of the present invention, which uses far infrared rays as a heat source for drying and maintains the number of living lactic acid bacteria in a high state to produce fermented milk powder, It is desirable that the drying temperature when milk is spray-dried under reduced pressure is 50 ° C. or lower, more preferably 35 ° C. to 38 ° C.

  That is, when the drying temperature is set to 50 ° C. or less (specifically, the temperature in the drying chamber in which the reduced pressure spray drying is performed is set to 50 ° C. or less), and more preferably 35 ° C. to 38 ° C., the produced fermentation The survival probability of lactic acid bacteria in milk powder is increased.

  According to the experiments by the inventors, when the method of the present invention is carried out with the temperature in the drying chamber where the reduced-pressure spray drying is performed being 50 ° C. or less, 40% or more of the lactic acid bacteria that survived the fermented milk before powdering treatment Remained alive after powdering.

  In addition, when the drying temperature was set to 35 ° C., 80% or more of the lactic acid bacteria that were alive in the fermented milk before the pulverization treatment were alive after the pulverization. Since the optimal growth temperature of lactic acid bacteria is around 37-38 ° C., when the method of the present invention is used at a drying temperature of 35 ° C.-38 ° C., the lactic acid bacteria continue to survive in the lactic acid bacteria powder with a very high probability. be able to.

  As described above, in the method for producing fermented milk powder by the reduced pressure spray drying method of the present invention, which uses far infrared rays as a heat source for drying, and maintains the number of living lactic acid bacteria in a high state to produce fermented milk powder. The pressure in the drying tower (drying chamber) when the dried milk is dried under reduced pressure spray drying while maintaining the drying temperature at 50 ° C. or lower, more preferably 35 ° C. to 38 ° C. under reduced pressure spray drying is, for example, 8 to The pressure can be reduced to 11 kPa.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 illustrates a preferred embodiment of a fermented milk powdering apparatus that can be applied to the implementation of the method for producing fermented milk powder by the reduced pressure spray drying method of the present invention.

  As shown in the figure, a blowout nozzle 2 is faced inside the upper part of the drying tower 1 sealed from the outside. A raw material tank 3 into which fermented milk to be pulverized is charged is connected to the blow-out nozzle 2 via a liquid feed pump 5 and a compressed air supply tank 4 is connected.

  The raw material tank 3 is provided with a heating stirrer 6 and is adjusted so that the temperature of the fermented milk supplied to the blowing nozzle 2 via the liquid feed pump 5 corresponds to a predetermined temperature in the drying tower 1. .

  An exhaust mechanism is connected to the lower part of the drying tower 1 via an exhaust pipe, whereby the pressure in the drying tower 1 is maintained at a predetermined low pressure. The exhaust mechanism comprises a vacuum pump 13, and the vacuum pump 13 is connected to the drying tower 1 via a main valve 15 a and a cold trap 14 for condensing water vapor from the exhaust from the drying tower 1.

  In addition, a baffle plate 17 is disposed at a portion connected to the exhaust mechanism from the drying tower 1 so that fermented milk powder or the like in the drying tower 1 does not flow into the exhaust mechanism side, and continuous powdering processing is possible. I have to.

  In this embodiment, as a heating means for supplying latent heat for evaporating the fermented milk sprayed from the blowing nozzle 2 in the drying tower 1 maintained at a predetermined low pressure, at the position where the blowing nozzle 2 is disposed. A far-infrared heater 9 is disposed in the vicinity, that is, in the upper space in the drying tower 1, and a hot water tube 10 is wound around the outer periphery of the lower part of the drying tower 1. Hot water is supplied to the hot water tube 10 from a constant temperature water tank 11 via a hot water circulation pump 12.

  As shown in FIG. 1, an upper temperature sensor 8a is provided at the upper part of the drying tower 1 where the far infrared heater 9 is arranged, and the upper part of the drying tower 1 according to the temperature detected by the upper temperature sensor 8a. The output of the far-infrared heater 9 is controlled by the temperature controller 7a so that the space is maintained at a predetermined temperature (for example, 50 ° C. or lower or 35 ° C. to 38 ° C.). For example, the far infrared heater 9 is controlled to be turned off when the temperature detected by the upper temperature sensor 8a exceeds a predetermined temperature, for example, 50 ° C.

  Moreover, the intermediate part temperature sensor 8c and the lower part temperature sensor 8b are arranged in the area | region of the drying tower 1 by which the hot water tube 10 is wound by the outer periphery, According to the temperature detected by these, in the drying tower 1 The temperature controller 7b controls the amount of hot water supplied to the hot water tube 10 by the temperature controller 7b so that the lower space is maintained at a predetermined temperature (for example, 35 ° C. to 38 ° C.). For example, when the temperature detected by the intermediate temperature sensor 8c and the lower temperature sensor 8b exceeds a predetermined temperature, for example, 50 ° C., the supply of hot water to the hot water tube 10 by the hot water circulation pump 12 is stopped. .

  In this embodiment, an outlet temperature sensor 8d is provided at the connection to the exhaust mechanism so that the temperature of the exhaust can be detected.

  Next, an example of the powdering method of the present invention using the fermented milk powdering apparatus shown in FIG. 1 will be described.

  A plain yogurt (manufactured by Meiji Dairies Co., Ltd.) adjusted to a solid content concentration of 11% is placed in the raw material tank 3, and the heating stirrer is operated to maintain the temperature at around 36 ° C.

  While operating the far-infrared heater 9 and operating the hot water circulation pump 12, hot water maintained at a temperature of about 40 ° C. in the constant temperature water tank 11 is sent to the hot water tube 10, and the temperature in the drying tower 1 is set to 37 ° C. Heat to.

  On the other hand, with the leak valve 15b attached to the cold trap 14 closed, the main valve 15a is opened and the vacuum pump 13 is operated to depressurize the interior of the drying tower 1 (depressurize to a pressure of 3.5 kPa to 4.5 kPa). did).

  Here, the liquid feed pump 5 is operated by a control device (not shown), supply of compressed air from the compressed air tank 4 is started, and spraying of fermented milk into the drying tower 1 is started.

  The pressure in the drying tower 1 is increased by spraying the compressed air and fermented milk into the drying tower 1. The pressure gauge (digital manometer) 16 grasps the pressure in the drying tower 1, and the inside of the drying tower 1. The pressure was maintained at 8 to 11 kPa.

  While the temperature in the drying tower 1 is detected by the upper temperature sensor 8a, the middle temperature sensor 8c, and the lower temperature sensor 8b, the output of the far-infrared heater 9 and the amount of warm water fed by the hot water circulation pump 12 are controlled to around 36 ° C. Maintained.

  After the pulverization step is completed, the operation of the liquid feed pump 5 is stopped and the supply of compressed air from the compressed air tank 4 is stopped by control by a control device (not shown), and fermented milk into the drying tower 1 is stopped. End spraying.

  After spraying from the nozzle 2 is completed, the main valve 15a is closed and the vacuum pump 13 is stopped. Next, the leak valve attached to the cold trap 14 is opened to return the inside of the drying tower 1 to atmospheric pressure, and the lower part of the drying tower 1 is opened to collect the product (dry powder).

(Confirmation test of lactic acid bacteria survival number)
As a method for measuring the number of lactic acid bacteria, which is an active ingredient of the raw material, an ATP method (bioluminescence method) that measures the concentration of ATP contained in the microorganism and estimates the number of living bacteria was adopted.

  Therefore, for the raw material (plain yogurt) used in the above examples, the initial ATP concentration before performing the pulverization treatment by reduced pressure spray drying and the temperature in the drying tower 1 during the reduced pressure spray treatment are 35 ° C., 50 ° C., The ATP concentration was measured in fermented milk powder produced by subjecting to the same conditions as in the above Examples except that the conditions were changed to 80 ° C. and 120 ° C. under reduced pressure spray drying.

Method for Measuring Initial ATP Concentration The initial ATP concentration was measured using an ATP analyzer (Toa DKK AF-100). This device is a device that causes a luminescence phenomenon by the luciferin-luciferase reaction, analyzes the ATP concentration by measuring the relative light emission amount (RLU: Relative Light Unit), and estimates the number of microorganisms.

 When the sample is colored, light emission is hindered and accuracy is lowered. Therefore, the sample was diluted 150 times with pure water and measured.

  The actual measurement procedure is described below. First, zero calibration (calibration) is performed using a zero calibration solution containing no ATP, a 100 nmol / L ATP standard reagent, a microorganism extraction reagent that decomposes microorganisms, and a luminescence reagent containing luciferin and luciferase.

  Thereafter, the diluted sample and the microorganism extraction reagent are placed in a measurement container and stirred for 20 seconds. Finally, when the luminescent reagent is put and the container is put into the apparatus, the measurement starts and the result can be obtained. Use 100 μl of each reagent and diluted sample. In addition, genuine reagents (Toa DKK AF-2A1, AF-2L1, AF-2K1) from the equipment manufacturer were used for measurement and zero calibration.

Change in ATP concentration with time After treatment under various temperature conditions, pure water is added to the obtained powder to reduce it, and it is diluted 150 times as in the case of measuring the initial ATP concentration. ATP analyzer (Toa DKK AF-100) To measure the ATP concentration. As a result, it was found that immediately after the reduction, the measured value was high even in the case of high-temperature drying and decreased with time. This is considered to be because ATP of dead bacteria produced by the reduced pressure spray drying treatment was measured immediately after the reduction. For this reason, in order to consider the retention of microbial activity, it was considered necessary to measure the change with time in the ATP concentration after reduction. Therefore, the ATP concentration after the reduction was measured immediately, and this was set to 0 minute, and then immersed in a constant temperature water bath at 30 ° C., and the change with time of the ATP concentration was measured every 30 minutes.

If it reduced with pure water after drying, for 30 minutes after the reduction in the influence of dead bacteria rapidly ATP is reduced, after 30 minutes, since 60 minutes later figures stabilized, after a lapse of 30 minutes, 60 The ATP concentration was measured when minutes passed.

 On the other hand, when the relationship between the number of lactic acid bacteria and the ATP concentration was confirmed for the raw material (plain yogurt) used in the above example, it was understood that the raw material had a linear proportional relationship as shown in FIG. .

With reference to this, the reduced-pressure spray-drying treatment was carried out under the same conditions as in the above-described embodiment except that the temperature in the drying tower 1 during the reduced-pressure spraying treatment was changed to 35 ° C., 50 ° C., 80 ° C., and 120 ° C. As a result of confirming the number of surviving lactic acid bacteria in the fermented milk powder produced, the number of lactic acid bacteria included in the solid content of fermented milk before 30 minutes and 60 minutes after drying the powder was 1 billion. As shown in FIG.

 That is, in the case of the lactic acid bacteria powder produced by the reduced pressure spray drying method of the present invention with the temperature in the drying tower 1 being 35 ° C., the number of lactic acid bacteria exceeding 80% before the treatment survives even after 60 minutes have passed since the production. Was.

Even when the drying temperature was 50 ° C., 50% or more of lactic acid bacteria survived after 30 minutes and 40% or more after 60 minutes .

 Furthermore, despite the optimal growth temperature of lactic acid bacteria being around 37-38 ° C., 16% of lactic acid bacteria survived even at a drying temperature of 80 ° C. and 6% even at a drying temperature of 120 ° C.

  Therefore, the reduced-pressure spray drying method of the present invention is considered to be an effective technique for drying and powdering probiotic foods, and in particular, the drying temperature is 50 ° C. or less, more preferably, considering the optimal growth temperature of lactic acid bacteria. When the reduced pressure spray drying method of the present invention is used at a drying temperature of from ℃ to 38 ℃, food containing lactic acid bacteria as probiotics (for example, fermented milk) is dried and powdered in large quantities at low cost. Is possible.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such embodiments.

  For example, in the above-described embodiment, the two-fluid nozzle type spray is performed in which the fermented milk that is the raw material and the compressed air are simultaneously sent to make the particles fine. However, a spray of a pressurized type can also be used.

  In addition, in the above embodiment, the heat for supplying the drying temperature during the reduced pressure spray drying process is provided with a far infrared heater only in the vicinity where the fermented milk is sprayed, and the supply of heat by the far infrared heater is reduced. In the lower part of the drying tower 1, heating means (a hot water heater that is wound around the outer periphery of the drying tower wall and in which hot water flows inside) is arranged on the wall of the drying tower, but other forms can also be adopted. is there.

  Heating by far infrared rays is advantageous in that it does not require a heat medium during heating and can efficiently supply heat even under reduced pressure. Therefore, it is possible to supply heat for drying only by a far infrared heater. For example, far-infrared heaters are provided not only in the vicinity where fermented milk is sprayed, but also in positions away from the position where fermented milk is sprayed in the drying tower, or fermented milk is sprayed in the drying tower It can also be set as the form by which the far-infrared heater is continuously arranged from the vicinity of a position to the position away from the position where fermented milk is sprayed in a drying tower.

 Thus, the form in which the far infrared heater is arranged only in the vicinity of the position where the fermented milk is sprayed in the drying tower (or drying chamber), the vicinity of the position where the fermented milk is sprayed in the drying tower, In the drying tower, a far infrared heater is arranged in both the position away from the position where the fermented milk is sprayed in the drying tower, or from the vicinity of the position where the fermented milk is sprayed in the drying tower. If the heating means is not arranged on the wall of the drying tower, such as the form in which the far-infrared heater is arranged continuously from the position where the fermented milk is sprayed in This is advantageous because the powder produced by the drying process can be prevented from adhering to the inner wall of the drying tower and reducing the powder recovery rate.

  However, heating means may be provided only on the walls of the drying tower. For example, as described in the above embodiment, a hot water heater that is wound around the outer periphery of the drying tower wall and in which hot water flows inside is provided over the entire length of the drying tower. In addition, it is possible to adopt a form such as providing a flow path through which the heated fluid passes.

  In addition, when deploying the heating means on the wall of the drying tower, the powder produced by the vacuum spray drying process adheres to the inner wall of the drying tower, so when deploying the heating means on the wall of the drying tower, As in the previous embodiment, a far infrared heater is provided in the vicinity of the position where the fermented milk is sprayed in the drying tower, and the fermented milk is sprayed in the drying tower where the supply of heat by the far infrared heater is reduced. It is desirable to provide heating means on the walls of the drying tower at a location remote from the location.

The figure explaining one preferable Example of the fermented milk powdering apparatus applicable to implementation of the manufacturing method of the fermented milk powder by the vacuum spray-drying method of this invention. The figure showing the relationship between the number of lactic acid bacteria in fermented milk (plain yogurt), and ATP density | concentration. The figure showing the number of lactic acid bacteria in the fermented milk powder manufactured by changing the drying temperature at the time of reduced pressure spraying processing by the reduced pressure spray drying method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drying tower 2 Outlet nozzle 3 Raw material tank 4 Compressed air supply tank 5 Liquid feed pump 6 Heating stirrer 7a, 7b Temperature controller 8a Upper part temperature sensor 8b Lower part temperature sensor 8c Middle part temperature sensor 8d Outlet part temperature sensor 9 Far infrared heater 10 Hot water tube 11 Constant temperature water tank 12 Hot water circulation pump 13 Vacuum pump 14 Cold trap 15a Main valve 15b Leak valve 16 Pressure gauge (digital manometer)
17 Baffle plate

Claims (4)

Spraying the fermented milk powder process is performed in the drying tower under reduced pressure and vacuum spray drying at a drying temperature of 35 to 38 ° C., live fermented milk powder to that reduced atomizer dried product containing lactic acid bacteria A method for producing fermented milk powder by the method ,
Spraying the fermented milk adjusted to a temperature corresponding to the temperature in the drying tower into the drying tower,
Far-infrared rays generated from a heat source for drying disposed in the internal space of the drying tower are used as means for supplying latent heat for evaporating the sprayed fermented milk.
A method for producing fermented milk powder by a reduced pressure spray drying method .   The fermentation by the vacuum spray drying method according to claim 1, wherein the number of living lactic acid bacteria in the fermented milk powder is 70% to 80% of the number of lactic acid bacteria in the fermented milk before the vacuum spray drying treatment is performed. A method for producing milk powder. The number of living lactic acid bacteria in the fermented milk powder at the time when 30 minutes have elapsed after the powder drying is 50% or more of the number of lactic acid bacteria in the fermented milk before performing the vacuum spray drying treatment. A method for producing fermented milk powder by the reduced pressure spray drying method. The number of live lactic acid bacteria in the fermented milk powder at the time when 30 minutes have passed after the powder drying is 50% or more of the number of lactic acid bacteria in the fermented milk before the vacuum spray drying treatment, and the time at which 60 minutes have passed after the powder drying. The number of living lactic acid bacteria in the fermented milk powder is 40% or more of the number of lactic acid bacteria in the fermented milk before performing the reduced pressure spray drying treatment. Manufacturing method.

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