Drying of microorganisms
AssigneeChr. Hansen A/S
InventorsMichelle MADSEN, Anders CLAUSEN
Life of this patent
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Abstract
The present invention relates to an improved method for drying microorganisms, especially lactic acid bacteria, in a spray dryer.
Claims39
A process for removing liquid (e.g. water) from a solution or suspension comprising a heat-labile material, such as a protein or a microorganism, esp. a LAB, characterized in that:
- a) the suspension or solution is sprayed into a gas in a spray dryer, the spray dryer having an outlet temperature of at most 70° C., and a pressure of at most 90 kPa (0.9 bar(a));
- and
- b) optionally the material (powder) resulting from step a) is removed (preferably continuously) from the spray dryer, so that the “dryer retention time” of the material is less than 20 minutes in the spray dryer.
A process for drying a microorganism (esp. a LAB) containing suspension, characterized in that:
- a) an aqueous suspension containing microorganisms (preferably having a concentration of at least 1.0E+8 microorganisms per ml) is sprayed into a gas in a spray dryer, the spray dryer having an outlet temperature of at most 70° C., and a pressure of at most 90 kPa (0.9 bar(a));
- and
- b) optionally the material (powder) resulting from the drying step a) is removed (preferably continuously) from the spray dryer, so that the “dryer retention time” of the material is less than 20 minutes in the spray dryer.
A process for drying a microorganism containing aqueous suspension, comprising the following steps:
- a) Contacting droplets of the suspension containing the microorganisms with a drying gas in gas in a spray dryer, the spray dryer having an outlet temperature of at most 70° C., and a pressure of at most 90 kPa (0.9 bar(a));
- and
- b) Removing the material (powder) from step a), eg by means of a cyclone and/or eg so the materials retention time in the drying apparatus is less than 20 minutes;
- c) optionally subjecting the resulting product from step b) to a further drying step, such as drying under reduced pressure, e.g. freeze-drying;
- and
- d) optionally packaging the resulting product, such as in an air-tight and/or moisture-tight package (optionally together with microorganisms of a different strain).
The process of any proceeding claim, wherein step b) is performed immediately after step a), eg by means of a cyclone which is able to separate the material from the gas.
The process of any preceding claim, wherein the material (powder) from step b) is cooled, e.g. to a temperature below 40° C., preferably immediately after removal from the spray dryer or the unit operation separating the dried powder from the gas.
The process of any preceding claim, wherein the “dryer retention time” of the dried powder is less than 2 minutes in the spray dryer.
The process of any preceding claim, characterized in that step a) is carried out at a gas outlet temperature of at most 60° C., advantageously between 10° C. and 50° C. and more preferably between 20° C. and 50° C.
The process of any preceding claim, characterized in that step a) is carried out at a hot-gas inlet temperature of at most 500° C., advantageously between 80° C. and 200° C. and more preferably between 80° C. and 160° C.
The process of any preceding claim, wherein step a) is carried out at a hot gas inlet temperature in the range from 100 to 200° C., or in the range from 100 to 150° C. or in the range from 80 to 160 or in the range 50 to 150° C. or in the range from 50 to 90° C. or or in the range from 60 to 80° C.
The process of any preceding claim, characterized in that after the drying step a) the powder has a particle size of between 1 and 200 microns and preferably between 5 and 100 microns, measured as the Dv50 value.
The process of any preceding claim, characterized in that the drying step takes place under a reduced pressure of between 15 and 80 kPa, preferably between 30 and 70 kPa.
The process of any preceding claim, characterized in that the drying step takes place at a temperature of between 10 and 60° C., preferably between 20 and 50° C.
The process of any preceding claim, wherein the duration of the drying step is a time suitable for obtaining a powder whose residual water content is at less than 20 percent by weight with respect to the total weight of the powder.
The process of the preceding claim, characterized in that the powder resulting from the drying step a) possesses a residual water content of between 0 and 15% by weight, preferably between 5 and 15 percent by weight, even more preferably between 6 and 12 percent by weight, with respect to the total weight of the powder.
The process of any preceding claim, wherein the duration of the drying step is a time suitable for obtaining a powder whose residual water content of the powder is at least 0.05.
The process of any preceding claim, wherein the gas contains less than 5% oxygen, such as less than 2%.
The process of any preceding claim, wherein the gas is selected from the group consisting of an inert gas (such as Nitrogen), a noble gas (such as Helium, Argon or Neon) etc., carbon dioxide, and an alkane gas (such methane), and a mixture thereof.
The process of any preceding claim, wherein the solution or suspension further comprises an additive that stabilizes the material/microorganism.
The process of the preceding claim, wherein the additive is selected from the group consisting of:
- Inositol, lactose, sucrose, trehalose, inulin, maltodextrin, skimmed milk powder, yeast extract, casein peptone, inosine, inosinemonophospate, monosodium glutaminate, Potato protein peptone, sodium caseinate, and sodium ascorbate, polysorbate.
The process of the preceeding claims, wherein the ratio heat labile material:additive is within the range from 1:0.5 to 1:5, such as from 1:1 to 1:4 or from 1:1½ to 1:3, (w/w of the dry weights).
The process of any preceding claim, wherein the microorganism is selected from the group consisting of:
- a yeast (eg Saccharomyces), a lactic acid bacterium, a Streptococcus species, a Lactobacillus species, a Lactococcus species, a Leuconostoc species, a Bifidobacterium Species, an Oenococcus species, a Bacillus species.
The process of any preceding claim, wherein the microorganism is selected from the group consisting of Streptococci species, and the outlet temperature is in the range 25-35° C., and the pressure in the drying unit is in the range 40 to 60 kPa.
The process of any preceding claim, wherein the microorganism is selected from the group consisting of Bifidobacterium species, and the outlet temperature is in the range 35-65° C., and the pressure in the drying unit is in the range 60 to 90 kPa.
The process of any preceding claim, wherein the microorganism is selected from the group consisting of Lactobacillus species, and the outlet temperature is in the range 35-65° C., and the pressure in the drying unit is in the range 60 to 90 kPa.
The process of any preceding claim, wherein the microorganism is selected from the group consisting of Lactococcus species, and the outlet temperature is in the range 35-65° C., and the pressure in the drying unit is in the range 40 to 60kPa.
The process of any preceding claim, wherein the microorganism is selected from the group consisting of Bacillus species, and the outlet temperature is in the range 35-65° C., and the pressure in the drying unit is in the range 60 to 90 kPa.
The process of any preceding claim, wherein the material from step b) is conveyed to a separator (such as a cyclone) by means of a cooling gas (such as a gas having a temperature below 50° C. or below 30° C., below 20° C., such as in the range 5 to 25° C.
The process of the preceding claim, wherein the cooling gas contains less than 5% oxygen, such as less than 2%.
The process of any preceding claim, wherein the cooling gas is selected from the group consisting of an inert gas (such as Nitrogen), a noble gas (such as Helium, Argon or Neon) etc., carbon dioxide, and an alkane gas (such methane), and a mixture thereof.
A product obtainable by the process of any preceding claim.
The product of the preceding claim, which is packaged (e.g. in an airtight container) without performing any further drying unit operation, such as freeze drying.
An apparatus usable in the process of any preceding claim, such as an apparatus substantially as depicted on FIG. 1.
The apparatus of the preceding claim, which comprises a spray dryer, a first cyclone coupled to the spray dryer, and a second cyclone coupled to the first cyclone.
The apparatus of the preceding claim, which comprises a spray dryer, a first cyclone coupled to the material outlet of the spray dryer, and a second cyclone coupled to the material outlet of the first cyclone.
The apparatus of any preceding claim, which further comprises an gas inlet between the first cyclone and the second cyclone, so that the gas will convey the material discharged from the first cyclone to the second cyclone.
The apparatus of any preceding claim, wherein the gas is a cooling gas (such as a gas having a temperature below 50° C., below 30° C., or below 20° C.).
The apparatus of the preceding claim, wherein the cooling gas contains less than 5% oxygen, such as less than 2%.
The apparatus of any preceding claim, wherein the cooling gas is selected from the group consisting of an inert gas (such as Nitrogen), a noble gas (such as Helium, Argon or Neon) etc., carbon dioxide, and an alkane gas (such methane), and a mixture thereof.
The apparatus of any preceding claim, which comprises means able to lower the pressure in the spray dryer to a pressure of at most 90 kPa.
Dependencies are inferred from the claim text.