Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; PREPARATION THEREOF
  • A23C9/00—Milk preparations; Milk powder or milk powder preparations
  • A23C9/15—Reconstituted or recombined milk products containing neither non-milk fat nor non-milk proteins
  • A23C9/1508—Dissolving or reconstituting milk powder; Reconstitution of milk concentrate with water; Standardisation of fat content of milk
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B11/00—Preservation of milk or dairy products
  • A23B11/10—Preservation of milk or milk preparations
  • A23B11/12—Preservation of milk or milk preparations by heating
  • A23B11/13—Preservation of milk or milk preparations by heating the materials being loose unpacked
  • A23B11/133—Preservation of milk or milk preparations by heating the materials being loose unpacked and progressively transported through the apparatus
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23G—COCOA; COCOA PRODUCTS, e.g. CHOCOLATE; SUBSTITUTES FOR COCOA OR COCOA PRODUCTS; CONFECTIONERY; CHEWING GUM; ICE-CREAM; PREPARATION THEREOF
  • A23G9/00—Frozen sweets, e.g. ice confectionery, ice-cream; Mixtures therefor
  • A23G9/04—Production of frozen sweets, e.g. ice-cream
  • A23G9/22—Details, component parts or accessories of apparatus insofar as not peculiar to a single one of the preceding groups
  • A23G9/30—Cleaning; Keeping clean; Sterilisation
  • A23G9/305—Sterilisation of the edible materials

Definitions

• Fresh milk is a relatively perishable product. Therefore , when milk is to be stored for a long period of time or to be transported over long distances , the milk is normally converted into milk powder by spray drying. In areas where no fresh milk is produced, it is desirable to convert the milk powder into a product, which corresponds to fresh milk to the highest possible extent. Therefore, the milk powder or dried milk is exposed to a recombining process , in which the powder is mixed with a suitable amount of water. If it is desired to obtain a full milk product rather than skimmed milk, a suitable amount of fat may also be added.
• the recombined milk from the mixing tank is normally passed through a pasteurizing apparatus, and the milk may also pass a fat metering and adding apparatus and a homogenizer.
• the homogenizer is very sensitive to air, in the known plants it is normally necessary to insert an air removing vacuum device in the tubing system upstream of the homogenizer, which gives rise to a substantial increase in cost of the plant.
• oxidation processes caused by the content of air in the recombined milk may give rise to a deterioration of the taste of the milk.
• the present invention provides a method and apparatus of the type described above, in which the foam formation problems described are eliminated or substantially reduced.
• the method according to the invention is of the type in which metered amounts of a pulverulent or particulate material is currently added to a liquid which is circulated through a tubing system including a mixing tank, and the method according to the invention is characterized in that said pulverulent or particulate material is sluiced into the tubing system in portions and substantially without entraining air.
• sluicing may, for example, be performed by means of a measuring chamber the ends of which may be sealingly closed by means of dampers , which are operated in such a manner that at least one damper will always be closed, so that the inner of the tubing system will not come into direct communication with the atmosphere.
• the sluicing of the pulverulent or particulate material is , however, advantageously performed by means of a metering apparatus of the type described in applicant's Danish patent application No . 3162/80 filed on 22nd July, 1980, which application is hereby incorporated herein by reference.
• a metering apparatus of the type described in applicant's Danish patent application No . 3162/80 filed on 22nd July, 1980, which application is hereby incorporated herein by reference.
• the substantially airless supply of pulverulent or particulate material makes it possible to perform a continuous recombining process .
• fresh liquid may continuously be supplied to and liquid milk product may simultaneously be continuously discharged from the tubing system .
• Such a continuous recombining process makes it possible to obtain an especially high production rate by means of a relatively small plant or system.
• the continuous process permits an almost instantaneous change in the production, for example by changing the mixing ratio between the pulverulent or particulate product and the liquid. This may, for example, be of importance if it is desired to change a production of recombined full milk for drinking purposes to a production of a milk product to be used by the production of for example yoghurt.
• fresh liquid is supplied to the tubing system or the mixing tank at a flow rate corresponding exactly to that at which the milk product is discharged from the system .
• This may advantageously be obtained thereby that the supply of fresh liquid to the tubing system is controlled by means of a level control device arranged within the mixing tank.
• the supply of fresh liquid will at any time be controlled so as to maintain the liquid level in the mixing tank substantially constant, which means that the amount of liquid in the tubing system including the mixing tank remains substantially constant .
• the liquid is advantageously circulated in the tubing system by means of a pump having a capacity substantially exceeding the capacity of the tubing system. This means that the liquid is circulated in the tubing system and the mixing tank several times , before it is discharged from the system, whereby a good mixing effect is obtained.
• the invention also relates to a plant for use in carrying out the method described above, said plant comprising a tubing system including a mixing tank, a pump for circulating liquid in the tubing system, and a metering apparatus for currently introducing metered amounts of pulverulent or particulate material into the tubing system, and the plant according to the invention is characterized in that the metering apparatus is in the form of a sluicing device adapted to sluice metered amounts of said pulverulent or particulate material into the tubing system without entraining substantial amounts of air.
• the plant shown in the drawing comprises a mixing tank 10 in the form of a cylindrical container provided with an air- tightly closing manhole cover 11 at the top thereof .
• This mixing tank 10 is communicating with a tubing system including a flow conduit 12 and a return conduit 13 which are connected to a centrifugal pump 14 with high capacity.
• a metering apparatus 15 arranged upstream of the centrifugal pump 14 is of the type described in applicant's above-mentioned Danish patent application No . 3162/80.
• the flow and return conduits 12 and 13 communicate with annular distributing tubes 16 and 17, respectively, which are arranged coaxially and axially spaced within the lower parts of the tank 10.
• These distributing tubes 16 and 17 are provided with openings , which are directed axially towards each other.
• the bottom of the mixing tank 10 is connected to a product discharge conduit 18 including a centrifugal pump 19 and passing through the preheating section 20 of a conventional plate pasteurizer 21.
• the preheating section 20 is communicating with a conventional homogenizer 23 through a conduit 22, and a fat metering device (not shown) is connected to the conduit 22 by means of a branched conduit 24.
• the part of the conduit 22 extending between the branched conduit 24 and the homogenizer 23 contains a conventional static mixer 25 serving to create turbulence and, consequently, a mixing effect in the liquid flowing through the mixer 25.
• the homogenizer 23 is connected to the heating section 26 of the pasteurizer 21 through a conduit 27, and the discharge opening of the heating section is communicating with a conduit 28, which contains a temperature control by-pass valve 29 having a first position in which liquid flowing from the heating section 26 is passed either through a conduit 30 to the cooling section 31 of the pasteurizer 21 , or via a by-pass conduit 32, which is provided with a one-way valve 33, back to the suction side of the centrifugal pump 19 as will be described more in detail below.
• a conduit 34 interconnects the cooling section 31 of the pasteurizer 21 and a valve 35, which is also communicating with the discharge conduit 18 via a connecting conduit 36.
• the valve 35 is also communicating with a product discharge conduit 37, which may lead to a storage tank for the finished product.
• the milk recombining plant shown in the drawing operates as follows :
• Tap water is supplied to the mixing tank 10 through a water supply conduit 38, when a manually operated shut-off valve 39 is opened.
• the water is introduced into the tank 10 through a shower or spraying device 40 arranged therein .
• a level sensor 41 controlling a flow regulating valve 42 in the conduit 38 causes the supply of water through the conduit 38 to stop , when the water within the mixing tank 10 has reached a predetermined level.
• the centrifugal pump 14 is started, whereby the water is circulated through the flow conduit 12, the return conduit 13, jand the tank 10.
• a number of metered amounts of milk powder substantially free of air and corresponding to the desired content of solid matter (apart from fat) in the recombined milk, are introduced into the return conduit 13.
• centrifugal pump 14 Due to the fact that the centrifugal pump 14 has a large capacity, which is preferably in the order of three to six times the production capacity of the plant, a substantial subatmospheric pressure will be created at the suction side of the pump which is important for correct functioning of the metering apparatus 15, and a strong turbulence will be created in the conduits 12 and 13 and in the mixing tank 10 so that a good mixing of the water and the milk powder is obtained.
• the centrifugal pump 19 is now started, whereby recombined milk is pumped from the mixing tank through the discharge conduit 18, the preheating section 20 of the pasteurizer 21, and the conduit 22 with the static mixer 25 to the homogenizer 23, which is started together with the pump 19.
• a metered amount of fat is currently supplied through the branched conduit 24.
• the mixer 25 When passing the mixer 25 the fat, which is in a heated and fluent condition, is dispersed in the milk, and the milk product is homogenized in the homogenizer 23.
• the homogenized recombined milk is passed from the homogenizer 23 via the conduit 27 to the heating section 26 of the pasteurizer, in which the final pasteurization takes place. Thereafter the pasteurized milk is passed through the conduit 28 to the temperature control by-pass valve 29.
• This valve is adapted to return the recombined milk to the suction side of the centrifugal pump 19 via the by-pass conduit 32 and the one-way valve 33 , if for some reason or another the milk has not obtained a predetermined pasteurization temperature, and the milk will then become recirculated through the pasteurizer and the homogenizer, till the desired temperature is obtained. Thereafter, the valve 29 is automatically switched to its other position, in which the pasteurized milk is passed from the conduit 28, and via the conduit 30 through the cooling section 31 of the pasteurizer 21 and then via the conduit 34, the valve 35, and the product discharge conduit 37 to a storage tank or another storage site, not shown .
• the metering apparatus 15 is controlled in dependency of the water supply through the supply conduit 38 in such a manner that the recombined milk obtains the desired relation between water and dry matter (excluding fat) , and the metering of fat through the branched conduit 24 is controlled in a similar manner.
• the valve 35 By shifting the valve 35 the recombined milk flowing through the conduit 34 may be recirculated to the suction side of the pump 19 via the connecting conduit 36 , if desired, and the metering of fat through the conduit 24 as well as the function of the metering apparatus 15 is then simultaneously stopped.
• Such shifting of the valve 35 may, for example, be made during the start up periods of the plant, and in case the supply of milk to the storage tank through the conduit 37 must temporarily be stopped for one reason or another.
• the above described function of the plant during its continuous operation is preferably controlled by means of suitable electrical and pneumatic control systems .
• the controlling may in principle , be made manually .
• the control of the metering apparatus 15 may possibly be made by means of electrical signals from a refractometer which may , for example, be positioned along the product discharge conduit 37 of the plant for currently measuring the content of dry matter (excluding fat) in the finished milk product. EXAMPLE .
• the mixing tank 10 may have a total volume of 150 liters, and the level sensor 41 may be adapted to secure that an amount of liquid of 100 liters is present in the tank.
• An amount of about 1740 liters of tap water is supplied to the tank 10 per hour, and the maximum pumping capacity of the centrifugal pump 14 is 100,000 liters per hour so as to obtain a substantial degree of recirculation through the conduits 12 and 13 and a vigorous turbulence in the mixing tank 10.
• Metered portions of skimmed milk powder, each in an amount of about 235 g, is supplied to the return conduit 13 by means of the metering apparatus 15 at a frequence corresponding to about 850 portions per hour.
• Liquid is pumped from the mixing tank 10 to the pasteurizer by means of the centrifugal pump 19 at a flow rate corresponding to 1940 liters per hour.
• Fat heated to 40 - 50°C so as to be in a fluent condition is supplied to the milk product through the branched conduit 24 by means of a conventional fat metering pump .
• the fat is added in an amount of about 60 kg fat per hour.
• the homogenizer 23 operates at a temperature of about
• the by-pass valve 29 is adapted to recirculate the milk through the by-pass conduit 32, if the milk is not heated to a temperature of at least about 72°C .
• the finished recombined milk is cooled to a temperature of about 5°C in the cooling section 31 of the pasteurizer 21, and the milk is passed to the storage tank at that temperature.
• the mixing tank 10 has the form of a cylindrical container with a diameter of about 55 mm, and the axial spacing between the annular distributing tubes 16 and 17 is about 200 mm .
• the distributing tubes are made from tubes having a diameter of about 50 mm.
• the centrifugal pump 14 is of a type marketed by Pasilac A/S , Silkeborg, Denmark, under the designation "ZMS 3"
• the metering apparatus 15 is of the type described in applicant's above Danish patent application No . 3162/80 and is arranged at the suction side of the centrifugal pump 14 at a position, where the pressure in the return line 13 is about 0.4 atmospheres .
• each mixing tank in a conventional milk recombining plant of the above type in which the recombining process is alternately performed in one or another of two mixing tanks , must have a volume of about 2000 liters in order to obtain a production capacity of the same order as that of the plant according to the invention described in the present example.
• the method and plant according to the invention has especially been disclosed in connection with recombining milk.
• the method and plant according to the invention could also be used for the production of milk products other than skimmed milk and full milk.
• the method and plant according to the invention may be used for the production of ice cream , and the powdered material metered by means of the metering apparatus 15 may then be ice cream powder.
• two or more metering apparatuses 15 in one and the same plant for metering pulverulent or particulate material.
• the metering apparatuses may be used for metering milk powder, cocoa powder, and sugar, respectively.
• the method and plant according to the invention could advantageously be used in connection with the mixing of a liquid and a pulverulent or particulate material in general, if problems arise due to foam formation when substantial volumes of air are introduced together with the pulverulent or particulate material.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Food Science & Technology (AREA)
• Polymers & Plastics (AREA)
• Wood Science & Technology (AREA)
• Zoology (AREA)
• Dairy Products (AREA)

Applications Claiming Priority (2)

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• 1980
  • 1980-07-22 DK DK316180A patent/DK156112C/da not_active IP Right Cessation
• 1981
  • 1981-07-21 WO PCT/DK1981/000072 patent/WO1982000240A1/en not_active Ceased
  • 1981-07-21 EP EP81902320A patent/EP0056411A1/de not_active Ceased

Non-Patent Citations (1)

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