PROCESS FOR MANUFACTURING PROPIONATE PRODUCTS

Abstract

A process for manufacturing propionate products through fermentation, including the steps of fermenting a carbon source selected from sugars and lactate in a fermentation medium by means of a propionic acid producing microorganism to provide a first fermentation broth comprising a propionate salt, recovering propionic acid producing microorganism from the first fermentation broth, subjecting the first fermentation broth from which propionic acid producing microorganism have been recovered to a water removal step to form a first propionate salt product, fermenting a carbon source comprising glycerol with the propionic acid producing microorganism recovered from the first fermentation broth in the presence of an inorganic alkaline salt to provide a second fermentation broth comprising a propionate salt, subjecting the second fermentation broth to a purification step comprising at least one precipitation step, to form a second propionate salt product. The process allows efficient manufacture of propionate salts products.

Claims

1. A propionate salt product comprising at least 85 wt. % of calcium salts of carboxylic acids, wherein the calcium salts comprise calcium propionate, calcium acetate and calcium succinate.

2. The propionate salt product according to claim 1 wherein the propionate salt product comprises at least 90 wt. %, preferably at least 95 wt. % of calcium salts of carboxylic acids.

3. The propionate salt product according to claim 1, wherein the propionate salt product has a propionate salt content in the range of 40-70 wt. %, an acetate salt content in the range of 3-20 wt. %, and a succinate salt content in the range of 0-10 wt. %.

4. The propionate salt product according to claim 1, wherein the acetate salt content is in the range of 8-15 wt. %, preferably 10-13 wt. %.

5. The propionate salt product according to claim 1, wherein the succinate salt content is in the range of 3-6 wt. %.

6. The propionate salt product according to claim 1, wherein the propionate salt product has a propionate salt content in the range of 50-90 wt. %, an acetate salt content in the range of 0-5 wt. %, and a succinate salt content in the range of 0-20 wt. %.

7. The propionate salt product according to claim 6, wherein the propionate salt content is in the range of 60-80 wt. %, more particular 70-80 wt. %.

8. The propionate salt product according to claim 6, wherein the acetate salt content is in the range of 0-2 wt. %.

9. The propionate salt product according to claim 6, wherein the succinate salt content is in the range of 0-10 wt. %, more particular 0-5 wt. %.

10. Use of the propionate salt product according to claim 1, for the preservation of feed and food.

Description

EXAMPLE 1: GLUCOSE FERMENTATION FOLLOWED BY GLYCEROL FERMENTATION

[0057] A fermenter comprising 5 kg medium was inoculated with a culture of Propionibacterium acidipropionici. The medium contained 80 g/kg glucose and 52 g/kg YEP (yeast extract paste, 50% dry solids). The fermenter was operated at 30 C. and with a pH of 6.5. The pH was controlled by adding Ca(OH)2 solution. After 45 hours the fermentation was stopped. The fermentation broth was centrifuged at 5000 RPM. The microorganism was present in the sediment of the centrifugation step.

[0058] In this step, the amount of biomass was increased from 20 gram added initially to 150 gram harvested, both calculated as dry weight.

[0059] 24 grams of biomass was added to a fermenter comprising 1 kg medium containing 80 g/kg glycerol and 52 g/kg YEP. The fermenter was operated at 30 C. and with a pH of 7.0. The pH was controlled by adding Ca(OH)2 solution.

[0060] The fermentation yielded a volumetric productivity of 1.2 gram calcium propionate per kilogram medium per hour. The total yield of the fermentation was 72 wt. %, calculated as grams propionate per gram glycerol.

EXAMPLE 2: WORK-UP OF GLUCOSE FERMENTATION BROTH

[0061] A glucose fermentation was carried out analogous to that described in the first paragraph of Example 1. The biomass was isolated therefrom by centrifugation as described therein. 1000 grams of the remaining fermentation broth was dried using a rotary evaporator, first under atmospheric pressure, then under vacuum. After 6 hours, a dry product was obtained.

[0062] The fermentation broth comprised the following organic acids, as determined using GC

TABLE-US-00001 TABLE 1 GC organic acids in fermentation broth component formic acid [% (w/w)] <0.02 acetic acid [% (w/w)] 0.57 propionic acid [% (w/w)] 2.4 ethanol [% (w/w)] <0.02 maleic acid [% (w/w)] <0.01 oxalic acid [% (w/w)] <0.01 sorbic acid [% (w/w)] <0.01 fumaric acid [% (w/w)] <0.01 succinic acid [% (w/w)] 0.24 lactic acid [% (w/w)] 0.02 pyruvic acid [% (w/w)] <0.03 2-hydroxy butyric acid [% (w/w)] <0.01

[0063] The solid product after the drying step had the following composition:

TABLE-US-00002 TABLE 2 composition of solid product component propionic acid [% (w/w)] 36 acetic acid [% (w/w)] 9.2 succinic acid [% (w/w)] 4.2 calcium [% (w/w)] 18.2 water [% (w/w)] 16.5 further solids balance

[0064] This example illustrates the step of water removal to form a first calcium propionate product. In commercial operation, the water removal step will be carried out by other methods, e.g., spray drying, but analogous results may be obtained.

EXAMPLE 3: WORK-UP OF GLYCEROL FERMENTATION BROTH

[0065] A glycerol fermentation broth obtained analogous to the second paragraph of Example 1 is processed as follows:

[0066] The fermentation broth obtained from the glycerol fermentation was subjected to a centrifugation step at 5000 RPM. The sediment of the centrifugation step was the microorganism. The supernatant was processed further. To the supernatant, active carbon was added in an amount of 0 wt. % per gram of calcium propionate, 0.1 wt. % per gram of calcium propionate, or 10 wt. % per gram of calcium propionate. The fermentation broth to which active carbon was added was kept for one hour at 60 C. The active carbon was removed by vacuum filtration using a 0.2 micron filter.

[0067] As can be seen from the following Table, an active carbon treatment did not result in the removal of calcium propionate from the system:

TABLE-US-00003 Ca Ca Ca propionate succinate acetate Glycerol Starting materials [% w/w] [% w/w] [% w/w] [% w/w] 102 C. - no active 5.35 0.22 <1 <0.15 carbon 102 C. - 0.1 (% w/w) 5.35 0.23 <1 <0.15 carbon 102 C. - 10 (% w/w) 5.48 0.23 <1 <0.15 carbon

[0068] Solid calcium propionate was precipitated from the purified fermentation medium by concentrating the medium through evaporation of water. Evaporation was carried out at 102-103 C. (medium temperature) in an oil bath of 150 C. under atmospheric pressure. After about two hours, nucleation occurred, as could be seen from the formation of a haze. At that point in time, the temperature of the oil bath was reduced to 120 C. to reduce the evaporation rate during crystallization. Some cool oil was added to the oil bath to accelerate the reduction in temperature. About one hour after the start of the nucleation, the evaporation was stopped.

[0069] The crystals were separated from the liquid using vacuum filtration or centrifugation.

[0070] Active carbon treatment resulted in a substantial decrease in color of the starting material for the evaporation step. Additionally, during the evaporation step, the solution darkened. This effect was much more pronounced for the sample which had not been subjected to an evaporation step than for the sample which had been subjected to the evaporation step. This can be seen from the APHA values in the following table.

TABLE-US-00004 Activated carbon Starting material Material obtained (% w/w) [APHA] [APHA] 0 280 6600 0.1 110 4200 10 <5 1900

[0071] The solid product obtained from the samples subjected to an active carbon treatment also had a much better color than the product obtained from the sample wherein no active carbon treatment was carried out.

[0072] The composition of the products was as follows:

TABLE-US-00005 Ca Ca Ca Wet cake S/L propionate succinate acetate Glycerol MC loss samples separation [% w/w] [% w/w] [% w/w] [% w/w] at 80 C..sup.1 102 C. - Vacuum 58.62 1.21 1.21 <0.1 35% blank filtration (Buchner funnel, 4- 7 m)) 102 C. - Centrifuge 76.46 0.47 1.21 <0.15 16% blank (5000 rpm, 100 m pore size, 1 minute) 102 C. - Centrifuge 87.92 0.28 1.34 <0.1 10% 0.1 (10000 rpm, (% w/w) 100 m carbon pore size, 1 minute 102 C. - Vacuum 61.16 1.61 1.21 <0.1 25% 10 filtration (% w/w) (Buchner carbon funnel, 4- 7 m)

[0073] 1 MC loss at 80 C. stands for the moisture content of the materials, determined by keeping the material for 16 hours in an oven at a temperature of 80 C.

[0074] As can be seen from the above table, the use of a centrifuge for solid liquid separation gave better results than the use of a vacuum funnel. The relevancy of this result for commercial scale operation is limited.

[0075] The wet products were dried at 80 C. for 16 hours to form a dried product.