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; MAKING THEREOF
  • A23C3/00—Preservation of milk or milk preparations
  • A23C3/02—Preservation of milk or milk preparations by heating
  • A23C3/03—Preservation of milk or milk preparations by heating the materials being loose unpacked
  • A23C3/033—Preservation of milk or milk preparations by heating the materials being loose unpacked and progressively transported through the apparatus
  • A23C3/037—Preservation of milk or milk preparations by heating the materials being loose unpacked and progressively transported through the apparatus in direct contact with the heating medium, e.g. steam
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
  • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
  • A23L3/16—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by heating loose unpacked materials
  • A23L3/18—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by heating loose unpacked materials while they are progressively transported through the apparatus
  • A23L3/22—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by heating loose unpacked materials while they are progressively transported through the apparatus with transport through tubes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P60/00—Technologies relating to agriculture, livestock or agroalimentary industries
  • Y02P60/80—Food processing, e.g. use of renewable energies or variable speed drives in handling, conveying or stacking
  • Y02P60/85—Food storage or conservation, e.g. cooling or drying

Definitions

• the present invention relates to heat treatment of heat sensitive liquids by steam injection.
• the heat treatment may have different purposes such as complete or partial sterilization or stabilization of liquid food products or pharmaceuticals, or stripping of volatile components from the liquid.
• UHT processing of milk comprises a heating step in which the milk is contacted with steam, followed by passage through a retention or holding zone to a flash cooling step wherein a momentaneous evaporative cooling takes place.
• the liquid passes through a holding zone decisive for the duration of the heat treatment and which is important for a uniform treatment of all parts of the liquid.
• vapours formed by this evaporation are withdrawn to a condenser, usually supplied with heat- regeneration means, and the non-evaporated part of the liquid is recovered from the bottom portion of the chamber as a marketable product or as an intermediate for further processing.
• the invention deals with a method of imparting an ultra-short, momentaneous heat treatment to a liquid by mixing steam into a stream of said liquid in a mixing zone, passing the stream of liquid through a holding zone and, after passage of a pressure controlling restricting means, subsequently into a flash cooler, which method is characterized in that the amount of steam mixed into the stream of liquid, is larger than the one which condenses by contacting the liquid, whereby the non-condensed portion of the steam serves to obtain passage of the liquid through the holding zone with reduced residence time therein compared with the residence time obtained in the same holding zone if only the amount of steam that condenses by contacting the liquid had been used.
• the method is not restricted to the use of any specific apparatus for forming the mixing zone, but it is essential that a quick and efficient mixing of the liquid and the steam is obtained using only a very short residence time for the liquid in the zone.
• the holding zone may encompass a separate unit or vessel, but it may also be a part of the same apparatus which creates the mixing zone and/or be formed in pipes and other equipment connecting the mixing zone with the restricting means.
• an adjustable valve may suitably be used which enables maintenance of a pres- sure in the mixing zone and the holding zone corresponding to the maximum temperature desired in the liquid.
• a non-adjustable restricting means such as an orifice plate
• said pressure can of course be obtained by adjusting the amounts of steam and liquid introduced into the mixing zone.
• the pressure Downstream of the restricting means the pressure is sufficiently low, below or above atmospheric pressure, to ensure a flash cooling of the liquid by evaporation.
• the surplus of steam, which reaches the flash cooling step, is withdrawn to the condenser together with the vapour created by the momentaneous evaporation of part of the heated liquid.
• a mixing zone is represented by 1. This may typically be formed by a Niro LSITM apparatus or other equipment enabling a similar fast mixing of steam and liquid.
• the liquid to be treated is fed to the mixing zone through a conduit 2 and steam is provided through conduit 3.
• the steam is introduced in an amount corresponding to the maximum temperature at which it is desired to heat the liquid, adjusted to compensate heat loss in the equipment .
• the steam may be superheated, but typically its temperature is only little above the saturation temperature or at the saturation temperature. It is an essential feature of the method according to the invention that the amount of steam introduced through 3 is in excess of the minimum amount required to obtain the desired heating, that means the amount of steam introduced is higher than the amount which condenses by contacting the liquid.
• the liquid after being heated and diluted by the water created by steam condensation therein passes into a pipe 4 which, together with the exit part of the equipment forming the mixing zone 1 constitutes a holding or retention zone. Also the non-condensed portion of the steam introduced through 3 passes from the mixing zone into the holding zone in pipe 4.
• valve 5 The liquid as well as the surplus of steam leaves the pipe 4 through a valve 5.
• this valve may be adjusted to provide a back pressure suitable for maintaining the desired conditions m 1 and 4.
• That part of the steam, which is not condensed, as well as the heated liquid pass from valve 5 into a flash cooler 6 where a pressure substantially below the one residing m the holding zone in pipe 4 causes a momentaneous evaporation, whereby that part of the liquid which does not evaporate is cooled to a tempera- ture typically not far from the temperature at which the liquid were introduced through conduit 2.
• vapour formed by this evaporation together with the non-condensed steam introduced through 5 is withdrawn through a duct 7 to a condenser (not shown) for pressure control.
• the liquid cooled by the evaporation collects in the bottom portion 8 of the flash cooler from where it is recovered, suitably by means of a pump 9.
• Adjustment according to the invention of the amount of steam led to the system through conduit 3 forms a very convenient and efficient way of adjusting the total residence time of the liquid at elevated temperature. By increasing said amount sufficiently it is possible to reduce the time period from the liquid contactes the steam m 1 to the liquid passes valve 5 for flash cooling to only a small fraction of the corresponding time period if no surplus of steam were used.
• the liquid to be treated can be a high viscous food product, preferably concentrate of milk or of a milk fraction or a fractionated or whole egg product, which is subjected to the heat treatment with a view of reducing the contents of microorganisms or microorganisms spores.
• Such heat treatment may preceed a spray drying or other processing of the liquid food product.
• the liquid can f . inst . be a concentrate of baby- food or of milk or milk fractions with or without addition of other components such as sugar, such products having a dry solids content of 40-75% by weight and the steam temperature is then above 110°C, preferably 120-160°C and the amount of steam is adjusted to obtain a residence time for the liquid at that temperature of 0.5 sec. or less, preferably 0.01- 0.2 sec.
• the amount of germs of Bacil - lus cereus can be reduced from 10 /ml to below 100/ml without heat damage of the product .
• SI Solubility Index
• the heat treatment of a whole milk concentrate the SI can be kept below 0.2 ml, typically below 0.1 ml.
• the SI is measured at a dry solids contents of 13% by weight according to ADMI .
• milk is intended to cover whole milk as well as skim milk.
• the maximum temperature is preferably only 65-70°C for a period less than 0.5 sec, preferably of 0.01-0.2 sec. to avoid coagulation of the prod- uct.
• suitable additives it is possible to use higher temperatures.
• Examples of other products suitable for being treated by the method according to the invention, either as such or as concentrates, are coffee whiteners, fruit juices, sweetened condensed milk and icecream mixes.
• the method may be used for liquids in the shape of solutions, emulsions, dispersions, suspensions og slurries, for instance within the food and drink industry or the pharmaceutical and cosmetical industry.
• the method may also find application when the liquid to be treated contains a compound more volatile than the other components thereof, in which case the treatment involves a removal of a substantial part of the volatile component by stripping thereof.
• the method may be used to reduce the contents of alcohol in a fermented brewerage while maintaining an acceptable taste and flavour thereof.
• the comparison comprised two runs.
• the starting material for both was a whole milk concentrate having a dry solids contents of 47% by weight and at an initial temperature of 65°C.
• the amount of steam led to the mixing zone corresponded to the one which, based on theoretical calculations (including heat loss to the equipment) , would condense completely when heating the liquid to the below specified temperatures.
• a whole milk concentrate having a dry solids contents of 47% by weight was heat treated from an initial temperature of 65°C to the various maximum temperatures indicated in the below Table. As it also appears from said Table when compared with the above Comparison Example, steam was used in an amount sub- stantially exceeding the amount corresponding to complete condensation.
• the concentrate was cooled to 65 °C in conventional manner in the evaporative cooler.
• Run 1 Run 2 Run 3 Run 4 Run 5
• the result of the spore concentration analysis indicated as ⁇ 1.0xl0 reflects the fact that actually no colony forming spores were revealed by propagation.
• the solubility index after heat treatment at 131°C was 0.1. when determined by using the same method as in the above Comparison Example.
• the material to be treated was a whole milk concentrate having a dry solids contents of 47% by weight and at an initial temperature of 65°C.
• the same equipment was used as in the above

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Polymers & Plastics (AREA)
• Health & Medical Sciences (AREA)
• Nutrition Science (AREA)
• Dairy Products (AREA)
• Food Preservation Except Freezing, Refrigeration, And Drying (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Crystals, And After-Treatments Of Crystals (AREA)

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• 1997
  • 1997-12-22 EP EP97947727A patent/EP1047303A2/de not_active Withdrawn
  • 1997-12-22 AU AU53983/98A patent/AU746891B2/en not_active Ceased
  • 1997-12-22 JP JP2000584723A patent/JP2002530123A/ja not_active Withdrawn
  • 1997-12-22 WO PCT/DK1997/000589 patent/WO1998007328A2/en not_active Application Discontinuation
• 1998
  • 1998-12-21 AR ARP980106571A patent/AR017226A1/es unknown

Non-Patent Citations (1)

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