Method for reducing the total bacteria count in aqueous dispersions of non-homogeneous two-phase or multi-phase mixtures

• US 20050013912A1
• Filed: 11/15/2002
• Published: 01/20/2005
• Est. Priority Date: 11/21/2001
• Status: Active Grant

• Current Assignee: E. Begerow GmbH & Co. (Eaton Corporation PLC.)
• Original Assignee: E. Begerow GmbH & Co. (Eaton Corporation PLC.)
• Inventors: Tesch, Ralf, Geiger, Gunther
• Granted Patent: US 7,527,817 B2
• Time in Patent Office: Days
• US Class Current: 426/478
• CPC Class Codes: A01J 11/06 Strainers or filters for milk
• CPC Class Codes: A23C 2210/208 Removal of bacteria by membrane filtration; Sterile filtration of milk products
• CPC Class Codes: A23C 9/1422 by ultrafiltration, microfiltration or diafiltration of milk, e.g. for separating protein and lactose; Treatment of the UF permeate
• CPC Class Codes: A23J 1/20 from milk, e.g. casein curds or cheese A23C; from whey
• CPC Class Codes: A61L 2/0017 Filtration
• CPC Class Codes: A61L 2/022 Filtration

Abstract

The invention relates to a method for reducing the total bacteria count in aqueous dispersions by means of sterile filtration of said dispersions using deep-bed filters (18, 22) pertaining to at least one deep-bed filter device, under pre-determined conditions, notably the temperature of the non-filtered parts the differential pressure in the deep-bed filters (18, 22) and the flow speed of the non-filtered part in the respective deep bed filter device. Known methods are further improved by using non-homogeneous two-phase or multi-phase mixtures as aqueous dispersions, in particular in the form of animal milk and products obtained therefrom such as skimmed milk having a predetermined dispersant content, in particular of lipids and proteins, and by the fact the deep-bed filters (18, 22) of the respective deep-bed filter device are electrically uncharged (unpolar), in that the total bacteria count in aqueous dispersions can be efficiently reduced by means of sterile filtration in a cost-effective manner and with high flow rates on a commercial scale, avoiding the pre-deposition of lipids and/or proteins before the actual sterile filtration.

Claims

1. A method for reducing the total bacteria count in aqueous dispersions by sterile filtration of the indicated dispersions by means of deep-bed filters (18, 22) of at least one deep-bed filter means under definable conditions, in particular the temperature of the unfiltered material, the differential pressure on the deep-bed filters (18, 22) and the incident flow velocity of the unfiltered material against the respective deep-bed filter means, characterized in that the aqueous dispersions are nonhomogeneous two-phase or multiphase mixtures, specifically in the form of animal milk and products obtained from it, such as skim milk with a definable content of dispersants, in particular lipids and proteins, and wherein the deep-bed filters (18, 22) of the respective deep-bed filter means are electrically uncharged (apolar), wherein the total bacteria count is reduced with an effectiveness which corresponds to a logarithmic bacteria retention value (LRV value) from 2 to 5, wherein the filter media are provided with a nominal separation rate of <

1 μ

m, in particular <

0.5 μ

m, preferably between 0.2 and 0.3 μ

m, and wherein the temperature of the respective dispersion which is to be filtered is chosen to be <

60°

C., preferably 40°

C. to 50°

C., but >

10°

C.

2. The process as claimed in claim 1, wherein the lipid and/or protein content of the dispersion remains essentially unchanged by deep-bed filtration.

3. The process as claimed in claim 1, wherein the total bacteria count of the filtrate is kept at <

1000 colony-forming units per millimeter (CFU/ml), in particular <

200 CFU/ml, preferably <

10 CFU/ml.

4. The process as claimed in claim 1, wherein the incident flow velocity against the filter (18, 22) is set at <

1500 l per m² and hour, in particular 500 to 1200 l per m² and hour, but >

300 l per m² and hour.

5. The process as claimed in claim 1, wherein the differential pressure on the filters (18, 22) is kept between 0 and 5 bar.

6. The process as claimed in claim 1, wherein the deep bed filter means is operated with several filter lines which are each equipped with at least one deep-bed filter (18, 22).

7. The process as claimed in claim 1, wherein deep-bed filters (18, 22) with definable, in particular different nominal separation rates are used.

8. The process as claimed in claim 1, wherein filter cartridges are used as the deep-bed filters.

9. The process as claimed in claim 1, wherein polypropylene is used as the material for the filter media.

10. The process as claimed in claim 1, wherein nonwovens, in particular nonwovens (32) obtained using the meltblown process, are used as the filter media.