Method of reducing emulsion by broth washing
Disclosed herein are processes for reducing or eliminating emulsion during the process of obtaining a microbial oil comprising one or more polyunsaturated fatty acids (PUFAs) from one or more microbial cells by washing the fermentation broth with at least 1× amount of water. Further disclosed herein is microbial oil comprising one or more PUFAs that is recovered from microbial cells by at least one process described herein.
1. A solvent-free process for obtaining a polyunsaturated fatty acid (PUFA) oil from microbial cells in a fermentation broth, wherein the process comprises:
(a) providing an unpasteurized fermentation broth comprising a biomass of PUFA oil-containing microbial cells;
(b) washing the biomass by diluting the unpasteurized fermentation broth with at least 2× amount of water sufficient to substantially remove components from the fermentation broth that cause emulsion formation during cell lysing and thereby form a washed fermentation broth comprising PUFA oil-containing microbial cells;
(c) separating the PUFA oil-containing microbial cells from supernatant liquid in the washed fermentation broth;
(d) pasteurizing the PUFA oil-containing microbial cells separated from the supernatant liquid of the washed fermentation broth to provide pasteurized PUFA oil-containing microbial cells;
(e) lysing the pasteurized PUFA oil-containing microbial cells to thereby form a lysed microbial cell composition;
(f) demulsifying the lysed microbial cell composition to form a demulsified lysed microbial cell composition comprising PUFA oil;
(g) separating the PUFA oil from the demulsified lysed microbial cell composition; and
(h) recovering the PUFA oil.
2. The process of claim 1 , wherein in step (b) comprises diluting the unpasteurized fermentation broth with between 2× and 4× amount of water.
3. The process of claim 1 , wherein step (c) is performed by centrifugation.
4. The process of claim 3 , wherein the microbial cells are capable of producing at least about 10 wt. %, at least about 20 wt. %, at least about 30 wt. %, or at least about 40 wt. % of their biomass as lipids.
5. The process of claim 4 , wherein said polyunsaturated lipids comprise one or any combination of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA).
6. The process of claim 5 , wherein the microbial cells are selected from the group consisting of algae, fungi, protists, bacteria, microalgae and mixtures thereof.
7. The process of claim 6 , wherein the microbial cells are from the genus Mortierella , genus Crypthecodinium , or order Thraustochytriales.
8. The process of claim 7 , wherein the microbial cells are from the order Thraustochytriales.
9. The process of claim 8 , wherein the microbial cells are from the genus Thraustochytrium, Schizochytrium , or mixtures thereof.
10. The process of claim 7 , wherein the microbial cells are from Mortierella Alpina.
11. The process of claim 1 , wherein steps (b) and (c) are repeated more than once by resuspending the washed PUFA oil-containing microbial cells in at least 1× distilled water and then separating the resuspended washed PUFA oil containing microbial cells from the supernatant liquid in the washed fermentation broth.