L-amino acid-containing feedstuff additive

1. A method for preparing a feed additive, comprising the following steps:

a) obtaining a low biomass content fermentation broth by:

i) fermenting an L-amino acid-producing microorganism in an aqueous culture medium to produce a fermentation broth;

ii) after the fermenting of step i) is complete:

aa) removing biomass from the fermentation broth to reduce the biomass content to, at most, 4% by weight;

bb) adding surface-active substance to the fermentation broth to a final concentration of 0.025 to 20% by weight; and

b) drying the low biomass content fermentation broth obtained in step a) in order to convert it into said feed additive;

wherein the concentrations of biomass and surface-active substance in the low biomass content fermentation broth are such that the feed additive of step b) is a particulate composition with a particle density of at least 1.20 g/cm 3 .

2. The method of claim 1 , wherein the concentrations of biomass and surface-active substance in the low biomass content fermentation broth are such that the feed additive of step b) is a particulate composition with a particle density of 1.20-1.30 g/cm 3 .

3. The method of claim 1 , further comprising completely or partially coating the particulate composition with an edible oil.

4. The method of claim 1 , wherein the L-amino acid is L-lysine, L-methionine, L-threonine, L-valine or L-tryptophan.

5. The method of claim 1 , wherein the amino acid is L-lysine and wherein, in a step after completion of fermentation and before the start of drying, ammonium sulphate and/or sulphuric acid is added to the fermentation broth in order to establish a sulphate/L-amino acid ratio of 0.85 to 1.2.

6. The method of claim 1 , wherein at least 30% by weight of the biomass is removed from the fermentation broth before drying.

7. The method of claim 1 , wherein the surface-active substance is selected from the group consisting of: corn steep liquor; lipids; antifoaming agents; surfactants; and mixtures thereof.

8. The method of claim 1 , wherein the surface-active substance is an antifoaming agent selected from the group consisting of: polysiloxanes; mono- and polyglycols; phospholipids; and fatty acid glycerides.

9. The method of claim 1 , wherein the fermentation broth used in the drying comprises:

a) an L-amino acid content, as amino acid base, of 12 to 48% by weight;

b) a solids content, including biomass, of 20 to 60% by weight;

c) a surface-active substance content of 0.025 to 20% by weight;

d) a sulphate to L-amino acid ratio of 0.8 to 1.2; and

e) a pH of 3.5 to 7.0.

10. The method of claim 1 , wherein drying is conducted by spray-drying.

11. The method of claim 1 , wherein the fermentation broth used in the drying step comprises:

a) a biomass content of at most 1% by weight;

b) an L-lysine content, as amino acid base, of 12 to 48% by weight;

c) a solids content, including biomass, of 30 to 50% by weight;

d) a surface-active substance content of 0.3 to 10% by weight;

e) a sulphate to L-lysine ratio of 0.8 to 1.2; and

f) a pH of 4.0 to 5.0.

12. The method of claim 1 , wherein:

a) at least 50% by weight of the biomass is removed from the fermentation broth before drying;

b) the surface-active substance is present in the fermentation broth before drying in an amount of 0.3 to 10% by weight;

c) drying is conducted by spray granulation using a fluidized bed reactor;

d) the L-amino acid is L-lysine.

13. The method of claim 12 , further comprising completely or partially coating the particulate composition with an edible oil.

14. The method of claim 13 , wherein, in a method step after completion of the fermentation and before the start of the drying, ammonium sulphate and/or sulphuric acid is added to the fermentation broth in order to establish a sulphate/L-amino acid ratio of 0.85 to 1.2.

15. The method of claim 14 , wherein at least 70% by weight of the biomass is removed from the fermentation broth before drying and wherein said feed additive is a particulate composition with a particle density of 1.20-1.30 g/cm 3 .

16. The method of claim 15 , wherein at least 90% by weight of the biomass is removed from the fermentation broth before drying.

17. The method of claim 1 , wherein the fermentation broth is converted directly into a granulate in one process step, and wherein the granulate comprises: 40-60% L-lysine; a mean particle diameter of 60-1500 μm; a biomass content of 0.1-2% by weight; a surface-active substance content of 0.5 to 15% by weight; and a water content of at most 3.5% by weight.

18. A method for preparing a feed additive, comprising the following steps:

a) fermenting an L-amino acid acid-producing microorganism in an aqueous culture medium to produce a fermentation broth;

b) after the fermenting of step a) is complete, converting the fermentation broth into a low biomass content fermentation broth by:

i) removing biomass from the fermentation broth to reduce the biomass content to, at most, 4% by weight, wherein at least 50% by weight of the biomass is removed from the fermentation broth before drying;

ii) adding a surface-active substance to the fermentation broth, wherein said surface-active substance is added to a final concentration of 0.025 to 20% by weight; and

c) drying the low biomass content fermentation broth obtained in step b) to convert it into a said feed additive;

wherein the concentrations of biomass and surface-active substance in the low biomass content fermentation broth are such that the feed additive of step c) is a particulate composition with a particle density of 1.20-1.30 g/cm 3 .

19. The method of claim 18 , wherein, in a step after completion of fermentation and before the start of drying, ammonium sulphate and/or sulphuric acid is added to the fermentation broth in order to establish a sulphate/L-amino acid ratio of 0.85 to 1.2.

20. The method of claim 18 wherein, said L-amino acid is L-lysine and said surface-active substance is selected from the group consisting of: corn steep liquor; lipids; antifoaming agents; surfactants; and mixtures thereof.