Spray freezing

Patent metadata

Field	Value
Publication number	US-10864457-B2
Application number	US-201515529317-A
Country	US
Kind code	B2
Filing date	Nov 30, 2015
Priority date	Nov 28, 2014
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

The present invention relates to an improved method for preservation of e.g. microorganisms, especially lactic acid bacteria, said method includes spray freezing.

First claim

The invention claimed is:

1. A process for removing liquid from a solution or suspension containing microorganisms, comprising:
(a) preparing droplets of a solution or suspension containing microorganisms by spraying the solution or suspension;
(b) spray-drying the droplets by contacting the droplets with a drying gas;
(c) freezing the droplets obtained in step (b) with a cryogenic gas to obtain a frozen product; and
(d) freeze-drying the frozen product under reduced pressure to a water activity (a w ) below 0.20, to produce a freeze-dried product.

2. The process of claim 1 , wherein the microorganisms comprise lactic acid bacteria (LAB).

3. The process of claim 2 , wherein:
spray-drying step (b) comprises spraying an aqueous suspension containing the LAB into a drying gas in a spray chamber; and
freezing step (c) comprises contacting the product resulting from step (b) with a cryogenic gas in a chamber to obtain a frozen powder as the frozen product.

4. The process of claim 2 , wherein:
spray-drying step (b) comprises spraying a liquid suspension containing the LAB into a chamber containing a drying gas; and
freezing step (c) comprises freezing the droplets resulting from step (b) by contacting the droplets with a cryogenic gas in a chamber to obtain a frozen suspension as the frozen product.

5. The process of claim 1 , wherein the spraying of step (a) is carried out by passing the solution or suspension through a spray nozzle or a rotating atomizing device, wherein the spray nozzle or rotating atomizing device results in droplets having a size of from 10 to 500 micrometers, measured as Dv90 values in micrometers.

6. The process of claim 1 , wherein the frozen product is collected by a cyclone having a maximum differential pressure drop across the cyclone of about 100 mm water column, or an electrostatic filter.

7. The process of claim 1 , wherein the spray-drying step (b) and freezing step (c) are independently conducted at a pressure in the range of from 60 to 200 kPa.

8. The process of claim 1 , wherein spray-drying step (b) is conducted with a retention time of less than 2 minutes in a spray dryer, and wherein the resulting product is directly introduced into a freezing chamber.

9. The process of claim 1 , wherein spray-drying step (b) is carried out with a drying gas inlet temperature of at most 300° C.

10. The process of claim 1 , wherein spray-drying step (b) is conducted at a temperature in the range from 20° C. to 250° C.

11. The process of claim 1 , wherein, after spray-drying step (b), the droplets have a size of between 20 and 400 microns measured as Dv90 values.

12. The process of claim 1 , wherein, after spray-drying step (b), the liquid content of the droplets is reduced by at least 5% by weight as compared to the liquid content of the starting suspension or solution.

13. The process of claim 12 , wherein, after spray-drying step (b), the liquid content of the droplets is between 20% and 85% by weight of the total weight of the droplets.

14. The process of claim 1 , wherein the drying gas and the cryogenic gas each independently contain less than 5% oxygen.

15. The process of claim 1 , wherein the drying gas and the cryogenic gas are independently selected from the group consisting of an inert gas, a noble gas, carbon dioxide, an alkane gas, and mixtures of two or more thereof.

16. The process of claim 1 , wherein the cryogenic gas has an inlet temperature in the range of from −50 to −250° C., and/or the cryogenic gas has a temperature of between −20° C. and −150° C. during the freezing step.

17. The process of claim 1 , wherein the solution or suspension further comprises an additive selected from inositol, lactose, sucrose, trehalose, inulin, maltodextrin, skimmed milk powder, yeast extract, casein peptone, inosine, inosinemonophospate, glutamine and salts thereof, casein and salts thereof, ascorbic acid and salts thereof, and polysorbate.

18. The process of claim 17 , wherein the ratio of microorganisms to additive is from 1:0.1 to 1:10 (w/w of the dry weights).

19. The process of claim 1 , wherein the microorganisms are selected from a yeast, a Streptococcus species, a Lactobacillus species, a Lactococcus species, a Leuconostoc species, a Bifidobacterium species, an Oenococcus species, and a Bacillus species.

20. The process of claim 1 , wherein the process is carried out in an apparatus comprising a two-chamber tower, the tower comprising:
a first (upper) chamber comprising (i) an atomizer adapted to atomize the suspension or solution, and (ii) an inlet for the drying gas; and
a second (lower) chamber comprising (iii) an inlet for the cryogenic gas, and (iv) an outlet coupled to a cyclone;
wherein the drying gas having a temperature in the range from 20° C. to 250° C. and the suspension or solution are sprayed into the first (upper) chamber, and the cryogenic gas having a temperature in the range of from −50 to −250° C. is sprayed into the second (lower) chamber.

21. The process of claim 1 , wherein the process is carried out in an apparatus comprising a chamber having (i) an atomizer for atomizing the solution or suspension, (ii) an inlet for the drying gas, (iii) an inlet for the cryogenic gas, and (iv) an outlet.

22. The process of claim 1 , further comprising packaging the freeze-dried product.

23. The process of claim 21 , wherein the inlet for the drying gas is integrated in the atomizer.

24. The process of claim 21 , wherein the outlet is connected to a cyclone.

25. A product obtained by the process of claim 1 .

26. The product of claim 25 , packaged in an airtight container.

Assignees

• Chr Hansen As

Inventors

• Madsen Michelle
• Jensen Allan
• Bisgaard-Frantzen Hans

Classifications

• C12N1/04 Primary

  Preserving or maintaining viable microorganisms (immobilised microorganisms C12N11/00) · CPC title

• C12N1/20

  Bacteria; Culture media therefor · CPC title

• B01D1/16 Primary

  by spraying (B01D1/22 takes precedence) · CPC title

• C12M45/22

  Means for packing or storing viable microorganisms (casings for storing cell samples A61B10/0096, preservation of living parts of the human or animal body A01N1/10) · CPC title

• B05B17/00

  Apparatus for spraying or atomising liquids or other fluent materials, not covered by the preceding groups (dropping or releasing powdered, liquid or gaseous matter in flight B64D1/16) · CPC title