L-amino acid-containing feedstuff additive

Abstract

By substituting biomass with a surface-active substance in a fermentation broth containing amino acid before spray-drying, granulated animal feed additives with improved product specifications were obtained.

Claims

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.sup.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.sup.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.sup.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.sup.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.

Description

WORKING EXAMPLES

Example 1

Influence of Biomass Content and Content of Surface-Active Substance on the Ability of the Fermentation Broth to be Granulated

(1) Fermentation broth containing lysine sulphate was provided and the biomass was removed therefrom by ultrafiltration. The fractions thereby obtained (biomass concentrate and biomass-free permeate) were then combined with one another in various proportions in order to obtain specific fermentation broths with differing biomass content. Fermentation broths having a biomass content of 0; 0.4; 3.1; 3.6; 7.1; 8.8; 10.4 and 12.0% by weight were prepared in this way.

(2) Furthermore, fermentation broths with no biomass and fermentation broths having a biomass content of 3.1 or 12.0% by weight were treated with various amounts of corn steep liquor. Corn steep liquor comprises lecithin as surface-active component. Corn steep liquor was added to the biomass-free fermentation broth in amounts of 0; 1.0; 2.3 and 4.6% by weight, and to the fermentation broth containing 3.1 and 12.0% biomass in an amount of 2.3% by weight respectively.

(3) A fluidized bed spray granulation was carried out using these materials. To this end, 300 g of comminuted lysine granulate were charged in each case and granulated in each case with 3800 g of fermentation broth having varying content of biomass and corn steep liquor and a dry mass of ca. 56% by weight.

(4) The spray granulation was carried out at an inlet temperature of 150-160° C. and a fluidized bed temperature of 85° C.

(5) After the spray granulation, the bulk density and the particle density were determined in each case.

(6) The bulk density was determined as follows: An empty measuring cylinder (250 ml volume) was placed on a balance, filled with the granular product and the weight per unit volume was then determined.

(7) To determine the particle density, the void spaces in the measuring cylinder were filled with methanol. The void volumes could thus be determined by the increase in weight and the known density of methanol (0.7918 g/ml). The difference between total volume and the volume of the methanol gives the particle volume. The particle density is then obtained, by basing the weight of the particle previously determined not on the total volume of the measuring cylinder but on the particle volume determined.

(8) Result

(9) It was found that all the mixtures investigated could be granulated. However, a stronger tendency to stickiness was observed with decreasing biomass. Surprisingly however, granulation was possible despite the complete absence of biomass, even if suitable measures may be required to control the particle size, for example, by using cutters in the fluidized bed or by external seeding. The ability to granulate in the absence of biomass was, however, very difficult.

(10) It has now been found that the addition of corn steep liquor leads to a distinctly lower tendency to stickiness and therefore a significantly improved ability to granulate the fermentation broth. Improved properties were achieved in this case with lower amounts of corn steep liquor, since the hygroscopicity of the product increased with increasing amounts of corn steep liquor such that an amount of 1 to 3% by weight of corn steep liquor was found to be particularly advantageous in accordance with the invention with respect to storage stability.

(11) Moreover, it has also been found, surprisingly, that the particle density is dependent on the biomass content and the surface-active substance content.

(12) It has been shown that the particle density increased with decreasing biomass and that the particle density of the biomass-free preparation further increased continuously due to the addition of corn steep liquor. This gives rise to distinct advantages in packing and transport costs.

(13) The results of the measurements are shown in the following tables.

(14) TABLE-US-00001 TABLE 1 Dependency of the particle density and bulk density on the biomass content in the starting fermentation broth. Biomass Particle density Bulk density [% by weight] [g/l] [g/l] 10.4 1113 613.2 8.8 1123 607.6 7.1 1118 620.4 3.6 1172 632.8 0.4 1185 636.4 0.0 1182 634.8

(15) The second experimental series showed that the particle density after the removal of biomass may be further increased by the addition of CSL. This effect is also observed in the presence of biomass but is less strongly pronounced. The higher the amount of biomass remaining, the lower the particle density which can be achieved, which can be seen in Table 2.

(16) TABLE-US-00002 TABLE 2 Dependency of the particle density of the granulate on the content of biomass and corn steep liquor (CSL) in the starting fermentation broth. Biomass CSL content Particle density [% by weight] [% by weight] [g/l] 0.0 0.0 1212 0.0 1.0 1217 0.0 2.3 1233 0.0 4.6 1250 3.1 2.3 1177 12.0 2.3 1168