US20140275613A1

US20140275613A1 - Conversion of free fatty acids to ethyl esters

Info

Publication number: US20140275613A1
Application number: US14/025,740
Authority: US
Inventors: Jeffrey Gerard Hippler; Louis Anthony Kapicak; Kristen Potter
Original assignee: Aurora Algae Inc
Current assignee: Aurora Algae Inc
Priority date: 2013-03-15
Filing date: 2013-09-12
Publication date: 2014-09-18
Also published as: CN105121623A; CN105263896A; US20140271706A1; EP2968244A1; WO2014151113A1; CN105209034A; IL240339A0; US20140273113A1; US20140275483A1; EP2970817A1; US20140274922A1; WO2014146133A3; WO2014151110A1; WO2014146133A2; US9445619B2; MX2015012321A; US20140275596A1; WO2014151116A1; CN105102598A; EP2968244A4

Abstract

Various embodiments of the present invention include systems and methods for converting free fatty acids to ethyl esters. An exemplary method may comprise contacting the free fatty acid with a non-polar solvent. A mineral acid and an alcohol may then be added to form a two-phase mixture. An aqueous phase my subsequently be removed from the mixture. The processes and methods may be used in the manufacture of supplements, pharmaceuticals, cosmetic and beauty products, feedstocks, and the like.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit and priority of U.S. Provisional Patent Application Ser. No. 61/800,114 filed on Mar. 15, 2013 and titled “(EPA) Algal Biomass and Oil Compositions and Impact on Health,” which is hereby incorporated by reference.
The present application claims the benefit and priority of U.S. Provisional Patent Application Ser. No. 61/800,029 filed on Mar. 15, 2013 and titled “Microalga Species and Industrial Applications,” which is hereby incorporated by reference.
The present application is related to U.S. Non-Provisional patent application Ser. No. ______, filed on ______ concurrently with the present application and titled “Algal Omega 7 Compositions,” which is hereby incorporated by reference.
The present application is related to U.S. Non-Provisional patent application Ser. No. ______ filed on ______ concurrently with the present application and titled Algal Oil Compositions,” which is hereby incorporated by reference.
The present application is related to U.S. Non-Provisional patent application Ser. No. ______, filed on ______ concurrently with the present application and titled “Algal Omega 7 and Algal Omega 3 Blend Compositions,” which is hereby incorporated by reference.
The present application is related to U.S. Non-Provisional patent application Ser. No. ______ filed on ______ concurrently with the present application and titled “Compositions and Methods for Utilization of Algal Compounds,” which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention is directed to systems and methods for producing ethyl esters from free fatty acids.

SUMMARY

Various embodiments of the present invention include systems and methods for converting free fatty acids into ethyl esters. An exemplary method may comprise contacting the free fatty acid with a non-polar solvent. A mineral acid and an alcohol may then be added to form a two-phase mixture. An aqueous phase may subsequently be removed from the mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is general flow chart of an exemplary method for producing ethyl esters.

FIG. 2 is a flow chart of an exemplary method for converting free fatty acids to ethyl esters.

DETAILED DESCRIPTION

Various embodiments of the present invention are directed to processes and methods for converting free fatty acids to ethyl esters. An exemplary method may comprise contacting the free fatty acid with a non-polar solvent to form a first mixture. An acid and an alcohol may then be added to form a second mixture. The second mixture may be heated and agitated to form a two-phase mixture, and an aqueous phase may be removed from the two-phase mixture. The processes and methods may be used in the manufacture of supplements, pharmaceuticals, cosmetic and beauty products, feedstocks, and the like.
Lipids are a broad class of chemical compounds that may be defined as “fatty acids and their derivatives, and the substances related biosynthetically or functionally to these compounds” [W. W. Christie, Gas Chromatography and Lipids: A Practical Guide (1989), p. 5]. Most lipids are soluble in organic solvents, but many are insoluble in water; however, given the diverse nature of lipids, some compounds regarded as lipids may also be soluble in water. Organic solvents in which lipids are soluble are generally non-polar solvents and may include pentane, cyclopentane, hexane, cyclohexane, benzene, toluene, 1,4-dioxane, chloroform, diethyl ether, methylene chloride, ethyl acetate, d-limonene, heptane, naphtha, and xylene, among others. Higher melting point lipids are typically solids at room temperature and are broadly classified as fats or waxes. Lipids with lower melting points are typical liquids at room temperature and are broadly classified as oils. Free fatty acids may be defined as non-esterified fatty acids.
Comprehensive classification of lipids is difficult because of their diverse nature. One classification system for biological lipids is based on the biochemical subunits from which the lipids originate. This system provides for various general categories of biological lipids, including fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, sterol lipids, and glycolipids.
Fatty acyls (or fatty acids and their conjugates and derivatives) are straight-chain carbon compounds that may be naturally synthesized via condensation of malonyl coenzyme A units by a fatty acid synthase complex. Fatty acyls typically have a carbon chain comprised of 4 to 24 carbon atoms, and often terminate with a carboxyl group (—COOH). Lipids containing fatty acyls can be hydrolyzed into alkali fatty acid salts using basic hydrolysis, a process known as saponification. Fatty acyls may be saturated or unsaturated, and may also include functional groups containing oxygen, nitrogen, sulfur, and halogens. Fatty acyls found in plant tissues commonly have a carbon chain comprised of 14, 16, 18, 20, or 24 carbon atoms.
Common fatty acyls of plant and animal origin can be divided into three broad categories of saturated fatty acids, monoenoic fatty acids, and polyunsaturated fatty acids. Saturated fatty acids are characterized as having 2 or more carbon atoms in the carbon chain with no double bonds between any of the carbon atoms. Example saturated fatty acids include ethanoic acid, butanoic acid, hexanoic acid, octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, and tetracosanoic acid. Monoenoic fatty acids are characterized as having a single carbon-carbon double bond in the carbon chain. The double bond is typically a cis-configuration, although some trans-configuration compounds are known. Example monoenoic fatty acids include cis-9-hexadecenoic acid, cis-6-octadecenoic acid, cis-9-octadecenoic acid, cis-11-octadecenoic acid, cis-13-docosenoic acid, and cis-15-tetracosenoic acid. Polyunsaturated fatty acids are characterized as having two or more carbon-carbon double bonds in the carbon chain. Example polyunsaturated fatty acids include 9,12-octadecadienoic acid, 6,9,12-octadecatrienoic acid, 9,12,15-octadecatrienoic acid, 5,8,11,14-eicosatetraenoic acid, 5,8,11,14,17-eicosapentaenoic acid, and 4,7,10,13,16,19-docosahexanoic acid.
Glycerolipids may be formed by joining fatty acids to glycerol by ester bonds. The majority of glycerolipids are formed by mono-, di-, or tri-substitution of fatty acids on the glycerol molecule. The most common naturally occurring glycerolipids are of the tri-substituted variety, known as triacylglycerols or triglycerides. Example glycerolipids include monoradylglycerols, monoacylglycerols, monoalkylglycerols, mono-(1Z-alkenyl)-glycerols, diradylglycerols, diacylglycerols, 1-alkyl,2-acylglycerols, 1-acyl,2-alkylglycerols, dialkylglycerols, 1Z-alkenylacylglycerols, di-glycerol tetraethers, di-glycerol tetraether glycans, triradylglycerols, triacylglycerols, alkyldiacylglycerols, dialkylmonoacylglycerols, 1Z-alkenyldiacylglycerols, estolides, glycosylmonoradylglycerols, glycosylmonoacylglycerols, glycosylmonoalkylglycerols, glycosyldiradylglycerols, glycosyldiacylglycerols, glycosylalkylacylglycerols, and glycosyldialkylglycerols.
Glycerophospholipids (or simply phospholipids) may be characterized by fatty acids linked through an ester oxygen to the first and second carbon atoms of the glycerol molecule, with a phosphate functional group ester-linked to the third carbon atom to the glycerol molecule. Other functional groups may also be linked to the phosphate functional group. In plant and animal cells, glycerophospholipids may serve as structural components of the cell membrane. Example glycerophospholipids include phosphatidyl choline (lecithin), phosphatidyl ethanolamine (cephalin), phosphatidyl inositol, phosphatidylserine, bisphosphatidylglycerol (cardiolipin), glycerophosphocholines, diacylglycerophosphocholines, 1-alkyl,2-acylglycerophosphocholines, 1-acyl,2-alkylglycerophosphocholines, 1Z-alkenyl,2-acylglycerophosphocholines, dialkylglycerophosphocholines, monoacylglycerophosphocholines, monoalkylglycerophosphocholines, 1Z-alkenylglycerophosphocholines, glycerophosphoethanolamines, diacylglycerophosphoethanolamines, 1-alkyl,2-acylglycerophosphoethanolamines, 1-acyl,2-alkylglycerophosphoethanolamines, 1Z-alkenyl,2-acylglycerophosphoethanolamines, dialkylglycerophosphoethanolamines, monoacylglycerophosphoethanolamines, monoalkylglycerophosphoethanolamines, 1Z-alkenylglycerophosphoethanolamines, glycerophosphoserines, diacylglycerophosphoserines, 1-alkyl,2-acylglycerophosphoserines, 1Z-alkenyl,2-acylglycerophosphoserines, dialkylglycerophosphoserines, monoacylglycerophosphoserines, monoalkylglycerophosphoserines, 1Z-alkenylglycerophosphoserines, glycerophosphoglycerols, diacylglycerophosphoglycerols, 1-alkyl,2-acylglycerophosphoglycerols, 1-acyl,2-alkylglycerophosphoglycerols, 1Z-alkenyl,2-acylglycerophosphoglycerols, dialkylglycerophosphoglycerols, monoacylglycerophosphoglycerols, monoalkylglycerophosphoglycerols, 1Z-alkenylglycerophosphoglycerols, diacylglycerophosphodiradylglycerols, diacylglycerophosphomonoradylglycerols, monoacylglycerophosphomonoradylglycerols, glycerophosphoglycerophosphates, diacylglycerophosphoglycerophosphates, 1-alkyl,2-acylglycerophosphoglycerophosphates, 1Z-alkenyl,2-acylglycerophosphoglycerophosphates, dialkylglycerophosphoglycerophosphates, monoacylglycerophosphoglycerophosphates, monoalkylglycerophosphoglycerophosphates, 1Z-alkenylglycerophosphoglycerophosphates, glycerophosphoinositols, diacylglycerophosphoinositols, 1-alkyl,2-acylglycerophosphoinositols, 1Z-alkenyl,2-acylglycerophosphoinositols, dialkylglycerophosphoinositols, monoacylglycerophosphoinositols, onoalkylglycerophosphoinositols, 1Z-alkenylglycerophosphoinositols, glycerophosphoinositol monophosphates, diacylglycerophosphoinositol monophosphates, 1-alkyl,2-acylglycerophosphoinositol monophosphates, 1Z-alkenyl,2-acylglycerophosphoinositol monophosphates, dialkylglycerophosphoinositol monophosphates, monoacylglycerophosphoinositol monophosphates, monoalkylglycerophosphoinositol monophosphates, 1Z-alkenylglycerophosphoinositol monophosphates, glycerophosphoinositol bisphosphates, diacylglycerophosphoinositol bisphosphates, 1-alkyl,2-acylglycerophosphoinositol bisphosphates, 1Z-alkenyl,2-acylglycerophosphoinositol bisphosphates, monoacylglycerophosphoinositol bisphosphates, onoalkylglycerophosphoinositol bisphosphates, 1Z-alkenylglycerophosphoinositol bisphosphates, glycerophosphoinositol trisphosphates, diacylglycerophosphoinositol trisphosphates, 1-alkyl,2-acylglycerophosphoinositol trisphosphates, 1Z-alkenyl,2-acylglycerophosphoinositol trisphosphates, monoacylglycerophosphoinositol trisphosphates, monoalkylglycerophosphoinositol trisphosphates, 1Z-alkenylglycerophosphoinositol trisphosphates, glycerophosphates, diacylglycerophosphates, 1-alkyl,2-acylglycerophosphates, 1Z-alkenyl,2-acylglycerophosphates, dialkylglycerophosphates, monoacylglycerophosphates, monoalkylglycerophosphates, 1Z-alkenylglycerophosphates, glyceropyrophosphates, diacylglyceropyrophosphates, monoacylglyceropyrophosphates, glycerophosphoglycerophosphoglycerols, diacylglycerophosphoglycerophosphodiradylglycerols, diacylglycerophosphoglycerophosphomonoradylglycerols, 1-alkyl,2-acylglycerophosphoglycerophosphodiradylglycerols, 1-alkyl,2-acylglycerophosphoglycerophosphomonoradylglycerols, 1Z-alkenyl,2-acylglycerophosphoglycerophosphodiradylglycerols, 1Z-alkenyl,2-acylglycerophosphoglycerophosphomonoradylglycerols, dialkylglycerophosphoglycerophosphodiradylglycerols, dialkylglycerophosphoglycerophosphomonoradylglycerols, monoacylglycerophosphoglycerophosphomonoradylglycerols, monoalkylglycerophosphoglycerophosphodiradylglycerols, monoalkylglycerophosphoglycerophosphomonoradylglycerols, 1Z-alkenylglycerophosphoglycerophosphodiradylglycerols, 1Z-alkenylglycerophosphoglycerophosphomonoradylglycerols, CDP-glycerols, CDP-diacylglycerols, CDP-1-alkyl,2-acylglycerols, CDP-1Z-alkenyl,2-acylglycerols, CDP-dialkylglycerols, CDP-monoacylglycerols, CDP-monoalkylglycerols, CDP-1Z-alkenylglycerols, glycosylglycerophospholipids, diacylglycosylglycerophospholipids, 1-alkyl,2-acylglycosylglycerophospholipids, 1Z-alkenyl,2-acylglycosylglycerophospholipids, dialkylglycosylglycerophospholipids, monoacylglycosylglycerophospholipids, monoalkylglycosylglycerophospholipids, 1Z-alkenylglycosylglycerophospholipids, glycerophosphoinositolglycans, diacylglycerophosphoinositolglycans, 1-alkyl,2-acylglycerophosphoinositolglycans, 1Z-alkenyl,2-acylglycerophosphoinositolglycans, monoacylglycerophosphoinositolglycans, monoalkylglycerophosphoinositolglycans, 1Z-alkenylglycerophosphoinositolglycans, glycerophosphonocholines, diacylglycerophosphonocholines, 1-alkyl,2-acylglycerophosphonocholines, 1Z-alkenyl,2-acylglycerophosphonocholines, dialkylglycerophosphonocholines, monoacylglycerophosphonocholines, monoalkylglycerophosphonocholines, 1Z-alkenylglycerophosphonocholines, glycerophosphonoethanolamines, diacylglycerophosphonoethanolamines, 1-alkyl,2-acylglycerophosphonoethanolamines, 1Z-alkenyl,2-acylglycerophosphonoethanolamines, dialkylglycerophosphonoethanolamines, monoacylglycerophosphonoethanolamines, monoalkylglycerophosphonoethanolamines, 1Z-alkenylglycerophosphonoethanolamines, di-glycerol tetraether phospholipids (caldarchaeols), glycerol-nonitol tetraether phospholipids, oxidized glycerophospholipids, oxidized glycerophosphocholines, and oxidized glycerophosphoethanolamines.
Sphingolipids may be characterized by a long-chain base (typically 12 to 26 carbon atoms) linked by an amide bond to a fatty acid and via a terminal hydroxyl group to complex carbohydrates or phosphorous functional groups. These lipids play important roles in signal transmission between cells and cell recognition. Example sphingolipids include sphing-4-enines (sphingosines), sphinganines, 4-hydroxysphinganines (phytosphingosines), sphingoid base homologs and variants, sphingoid base 1-phosphates, lysosphingomyelins and lysoglycosphingolipids, N-methylated sphingoid bases, sphingoid base analogs, ceramides, N-acylsphingosines (ceramides), N-acylsphinganines (dihydroceramides), N-acyl-4-hydroxysphinganines (phytoceramides), acylceramides, ceramide 1-phosphates, phosphosphingolipids, ceramide phosphocholines (sphingomyelins), ceramide phosphoethanolamines, ceramide phosphoinositols, phosphonosphingolipids, neutral glycosphingolipids, simple Glc series, GalNAcβ1-3Galα1-4Galβ1-4Glc-(globo series), GalNAcβ1-4Galβ1-4Glc-(ganglio series), Galβ1-3GlcNAcβ1-3Galβ1-4Glc-(lacto series), Galβ1-4GlcNAcβ1-3Galβ1-4Glc-(neolacto series), GalNAcβ1-3Galα1-3Galβ1-4Glc-(isoglobo series), GlcNAcβ1-2Manα1-3Manβ1-4Glc-(mollu series), GalNAcβ1-4GlcNAcβ1-3Manβ1-4Glc-(arthro series), acidic glycosphingolipids, gangliosides, sulfoglycosphingolipids (sulfatides), glucuronosphingolipids, phosphoglycosphingolipids, basic glycosphingolipids, amphoteric glycosphingolipids, and arsenosphingolipids.
Saccharolipids may be comprised of fatty acids linked directly to a sugar backbone. Typically, a monosaccharide takes the place of the glycerol molecule that forms the backbone of other lipids such as glycerolipids and glycerophospholipids. Saccharolipids play a role in the bilayer structure of cell membranes. Example saccharolipids include acylaminosugars, monoacylaminosugars, diacylaminosugars, triacylaminosugars, tetraacylaminosugars, pentaacylaminosugars, hexaacylaminosugars, heptaacylaminosugars, acylaminosugar glycans, acyltrehaloses, and acyltrehalose glycans.
Glycoglycerolipids may be comprised of fatty acids linked through an ester oxygen to the first and second carbons of a glycerol molecule, with a carbohydrate functional group ester-linked to the third carbon atom. The carbohydrate functional group may include one or more sugar monomers. Other functional groups may also be linked to the carbohydrate functional group. Example glycoglycerolipids include monogalactosyldiacylglycerols, digalactosyldiacylglycerols, trigalactosyldiacylglycerols, tetragalactosyldiacylglycerols, polygalactosyldiacylglycerols, monoglucosyldiacylglycerols, diglucosyldiacylglycerols, monogalactosylmonoacylglycerols, digalactosylmonoacylglycerols, sulfoquinovosyldiacylglycerols, acylsulfoquinovosyldiacylglycerols, acylgalactosylglucossyldiacylglycerols, kojibiosyldiaacylglycerols, galactofuranosyldiacylglycerols, galactopyranosyldiacylglycerols, 1,2-diacyl-3-O-a-D-glucuronyl-sn-glycerols, glucosylglucuronyldiacylglycerols, galacturonyldiacylglycerols, polyglucosyldiacylglycerols, and monoglucosyldiacylglycerols.
Sterol esters may be characterized as comprising alcohols sharing a fused four-ring steroid structure ester-linked to one or more fatty acyls. Examples include cholesteryl esters, campesterol esters, stigmasterol esters, sitosterol esters, avenasterol esters, fucosterol esters, isofucosterol esters, and ethylcholesteryl esters.
FIG. 1 illustrates a general process for converting free fatty acids into ethyl esters. Free fatty acids may be obtained from a variety of sources. For example, crude algal oil obtained from various algae species may be converted to free fatty acids in an aqueous system (step 105). The crude algal oil is typically a mixture of oils, waxes, chlorophyll, and other species that originally supported the functioning of the algae plant. The free fatty acids may be extracted from other algal impurities. At step 110, the free fatty acids may be mixed with a mineral acid and an alcohol to impart a phase separation of the mixture. An esterification reaction may occur (step 115) to convert the free fatty acids to the ethyl ester form. The ethyl esters may then be isolated from the mixture (step 120).
Esterification is the chemical process of producing esters. Most commonly, esters are formed from a fatty acid and an alcohol. For example, carboxylic acid (a fatty acid) may react with ethanol in the presence of an acid catalyst to produce ethyl esters and water according to Equation 1.
RCOOH+CH₃CH₂OH→RCOOCH₂CH₃+H₂O Equation 1
The reaction of Equation 1 is also reversible in that the water formed will react with the ethyl ester in the presence of an acid to produce free fatty acids. This reverse reaction has a higher propensity to occur than the esterification reaction, meaning that the produced water should be removed from the reaction mixture to achieve higher conversion of the free fatty acid. Without removal of the water, a reaction mixture of 10 percent water and 90 percent ethanol on a molar basis may produce a mixture that is approximately 30 percent free fatty acid and 70 percent ethyl ester on a molar basis (that is, about a 70 percent conversion).
In various embodiments, various algae species may be the source of the crude algal oil from which the free fatty acids may be obtained. Algae are mostly aquatic photosynthetic organisms that range from microscopic flagellate to giant kelp. Algae may be loosely grouped into seven categories: Euglenophyta (euglenoids), Chrysophyta (golden-brown algae), Pyrrophyta (fire algae), Dinoflagellata, Chlorophyta (green algae), Rhodophyta (red algae), Paeophyta (brown algae), and Xanthophyta (yellow-green algae). Lipid extracted from any algae genus may be used in the various embodiments of the present invention, including Amphora, Anabaena, Anikstrodesmis, Botryococcus, Chaetoceros, Chlorella, Chlorococcum, Cyclotella, Cylindrotheca, Dunaliella, Emiliania, Euglena, Glossomastix, Haematococcus, Isochrysis, Monochrysis, Monoraphidium, Nannochloris, Nannochloropsis, Navicula, Nephrochloris, Nephroselmis, Nitzschia, Nodularia, Nostoc, Oochromonas, Oocystis, Oscillatoria, Pavlova, Phaeodactylum, Picochloris, Platymonas, Pleurochrysis, Porphyra, Pseudoanabaena, Pyramimonas, Scenedesmus, Stichococcus, Synechococcus, Synechocystis, Tetraselmis, Thalassiosira, and Trichodesmium.
Additionally, free fatty acids from non-algae sources, such as plant oils and animal oils may also be used in various embodiments, as may various petroleum-based products and synthetic oils. Non-limiting examples of sources of non-algae free fatty acids include fish oil, tung oil, colza oil, soy bean oil, corn oil, peanut oil, palm oil, rape seed oil, sunflower oil, safflower oil, corn oil, mineral oil, coconut oil, linseed oil, olive oil, sesame seed oil, animal fats, frying oil waste, sewage sludge, and the like.
FIG. 2 illustrates an exemplary method 200 of producing ethyl esters from free fatty acids according to various embodiments. At step 205, the free fatty acids may be extracted from algal impurities or other impurities using a non-polar solvent. Non-limiting examples of non-polar solvents include hexane, cyclohexane, heptane, d-limonene, naphtha, xylene, toluene, pentane, cyclopentane, benzene, 1,4-dioxane, chloroform, diethyl ether, dichloromethane, tetrahydrofuran, and methyl acetate. In various embodiments, the algal oil containing free fatty acids may be contacted with the non-polar solvent to form a first mixture. The algal oil may comprise approximately 3 percent to approximately 15 percent by weight of the first mixture. The free fatty acids may dissolve in the non-polar solvent.
The algal impurities in the algal oil may not dissolve in the non-polar solvent. According to various embodiments, an additional step (not shown in FIG. 2) may occur after step 205 to remove these impurities. Filtration or any other technique known in the art may be used to remove the impurities.
In various embodiments, one or more acid and one or more alcohols may be added to the first mixture to form a second mixture (step 210). The acid and the alcohol may be individually added to the first mixture, or may be first premixed before adding to the first mixture. In various embodiments, the acid may be a mineral acid or mixture of mineral acids. Non-limiting examples of mineral acids are sulfuric acid, hydrochloric acid, nitric acid, perchloric acid, hydrobromic acid, boron trifluoride, hydroiodic acid, and mixtures thereof. Non-limiting examples of alcohols are methanol, ethanol, propanol, butanol, pentanol, and mixtures thereof.
The composition of the second mixtures according to various embodiments may comprise approximately 0.25 percent to 5 percent by weight acid and approximately 3 percent to 20 percent alcohol by weight. The second mixture may also contain water. The water may be originally present in any of the ingredients of the second mixture and may also be formed as shown above in Equation 1. In various embodiments, the water content of the second mixture may range from approximately 0.1 percent to 10 percent by weight.
The second mixture may then be agitated and heated to a desired reaction temperature (step 215). The reaction may produce a two-phase system in which one of the phases is an aqueous phase according to various embodiments. Agitating the mixture may facilitate the mass transfer between the first mixture and the second mixture. In various embodiments, the second mixture may be heated to approximately 50° C. to 100° C., and the reaction time may range from approximately several minutes to several hours to allow the reaction to proceed to the desired completion of amount of conversion (step 220). In certain embodiments, the reaction time may be approximately one hour.
At step 225, the agitation may be stopped to facilitate separation of the aqueous phase. In various embodiments, the reaction time may be further extended to promote further conversion (step 230) and then the aqueous layer may be removed (step 235). Alternatively, the aqueous layer may be removed (step 240) and then the reaction is allowed to proceed further (step 245).
The aqueous layer may be removed by decanting after stopping the agitation and allowing the phases to separate according to various embodiments. However, any method of separation of the phases known in the art may be used, such as using a centrifuge or an extractor. The phase separation may occur while the second mixture is being agitated or after agitation is stopped.
In various embodiments, performing the method 200 in the non-polar solvent in the presence of the acid promotes the formation of the two-phase mixture, comprising a solvent phase and an aqueous phase. The solvent phase preferentially contains the free fatty acid, the alcohol, and a catalytic amount of the acid. The aqueous phase may preferentially contain the water and the remaining acid and alcohol. According to various embodiments, the aqueous phase acts to pull the water out of the solvent phase (the phase in which the reaction in Equation 1 above is predominantly occurring) and into the aqueous phase. The water may be originally present in the components of the second mixture or may be formed as a product of the reaction as shown in Equation 1. As described previously, the presence of water in the reaction mixture will tend to move the equilibrium of the system more towards re-forming the free fatty acids and away from producing ethyl esters. Thus, by removing the water from the solvent phase, the reaction may be allowed to proceed to a surprisingly and unexpectedly higher conversion rate than would be predicted in a single phase system. In various embodiments, conversions of approximately 98 percent of the free fatty acid to ethyl esters have been achieved. Further conversion of the free fatty acids up to approximately 99.5 percent or more may be achieved by removing the aqueous phase when the reaction is near equilibrium and allowing additional reaction time.
The methods described herein may be used to produce ethyl ester forms of free fatty acid. A fatty acid is a carboxylic acid with a long aliphatic tail (chain), which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Saturated fatty acids have no double bonds between carbon atoms. Unsaturated fatty acids have one or more double bonds between carbon atoms. When counting from the terminal methyl carbon toward the carbonyl carbon on an unsaturated fatty acid, the first double bond signifies the omega double bond, such as observed in omega 3, omega 6, or omega 7 fatty acids.
Palmitoleic acid (POA) is an omega-7 monounsaturated fatty acid with a 16-carbon chain with one double bond, denoted as C16:1 n7. A beneficial fatty acid, it has been shown to suppress inflammation. Dietary sources of omega-7 are found in animal and plant sources, including sea buckthorn berries, macadamia nuts, cold water fish and dairy fat. These sources, however, are not concentrated and/or purified sources of POA and often contain a mixed fatty acid profile of saturated and polyunsaturated fats.
Various exemplary algal omega 7 compositions may comprise by dry weight from about approximately 10% to about approximately 99% palmitoleic acid. Such algal compositions may also include (either individually or any combination of) by dry weight: from about approximately 0% to about approximately 20% saturated fatty acids; from about approximately 0% to about approximately 10% arachidonic acid; substantially no (i.e. less than approximately 0.5%) docosahexaenoic acid; and/or from about approximately 0% to about approximately 10% eicosapentaenoic acid.
Additionally, the various exemplary algal omega 7 compositions may further be in ethyl ester form. Such ethyl esters are derived by reacting free fatty acids with ethanol. Called esterification, the resulting ethyl ester allows for the fractional distillation (concentration) of the long chain fatty acids at lower temperatures. This step allows for the selective concentration of the fatty acids to levels greater than found in nature.
Eicosapentaenoic acid (EPA) is an omega-3 fatty acid with a 20-carbon chain with five double bonds, denoted as 20:5 n3. EPA is a polyunsaturated fatty acid that acts as a precursor to certain eicosanoids. Sources of EPA include oily fish (fish oils), algal oil, egg oil, squid oil, some plant oils such as that found in seaweed. While the fish do not naturally produce EPA, they obtained it through algae food sources. Various exemplary algal omega 3 compositions may comprise by dry weight from about approximately 10% to about approximately 99% eicosapentaenoic acid. Such algal compositions may also comprise by dry weight from about approximately 0% to about 99% other fatty acids.
An exemplary computing system may be used to implement various embodiments of the systems and methods disclosed herein. The computing system may include one or more processors and memory. Main memory stores, in part, instructions and data for execution by a processor to cause the computing system to control the operation of the various elements in the systems described herein to provide the functionality of certain embodiments. Main memory may include a number of memories including a main random access memory (RAM) for storage of instructions and data during program execution and a read only memory (ROM) in which fixed instructions are stored. Main memory may store executable code when in operation. The system further may include a mass storage device, portable storage medium drive(s), output devices, user input devices, a graphics display, and peripheral devices. The components may be connected via a single bus. Alternatively, the components may be connected via multiple buses. The components may be connected through one or more data transport means. Processor unit and main memory may be connected via a local microprocessor bus, and the mass storage device, peripheral device(s), portable storage device, and display system may be connected via one or more input/output (I/O) buses. Mass storage device, which may be implemented with a magnetic disk drive or an optical disk drive, may be a non-volatile storage device for storing data and instructions for use by the processor unit. Mass storage device may store the system software for implementing various embodiments of the disclosed systems and methods for purposes of loading that software into the main memory. Portable storage devices may operate in conjunction with a portable non-volatile storage medium, such as a floppy disk, compact disk or Digital video disc, to input and output data and code to and from the computing system. The system software for implementing various embodiments of the systems and methods disclosed herein may be stored on such a portable medium and input to the computing system via the portable storage device. Input devices may provide a portion of a user interface. Input devices may include an alpha-numeric keypad, such as a keyboard, for inputting alpha-numeric and other information, or a pointing device, such as a mouse, a trackball, stylus, or cursor direction keys. In general, the term input device is intended to include all possible types of devices and ways to input information into the computing system. Additionally, the system may include output devices. Suitable output devices include speakers, printers, network interfaces, and monitors. Display system may include a liquid crystal display (LCD) or other suitable display device.
Display system may receive textual and graphical information, and processes the information for output to the display device. In general, use of the term output device is intended to include all possible types of devices and ways to output information from the computing system to the user or to another machine or computing system. Peripherals may include any type of computer support device to add additional functionality to the computing system. Peripheral device(s) may include a modem or a router or other type of component to provide an interface to a communication network. The communication network may comprise many interconnected computing systems and communication links. The communication links may be wireline links, optical links, wireless links, or any other mechanisms for communication of information. The components contained in the computing system may be those typically found in computing systems that may be suitable for use with embodiments of the systems and methods disclosed herein and are intended to represent a broad category of such computing components that are well known in the art. Thus, the computing system may be a personal computer, hand held computing device, telephone, mobile computing device, workstation, server, minicomputer, mainframe computer, or any other computing device. The computer may also include different bus configurations, networked platforms, multi-processor platforms, etc.
Various operating systems may be used including Unix, Linux, Windows, Macintosh OS, Palm OS, MS-DOS, MINIX, VMS, OS/2, and other suitable operating systems. Due to the ever changing nature of computers and networks, the description of the computing system is intended only as a specific example for purposes of describing embodiments. Many other configurations of the computing system are possible having more or less components.
As used herein, the terms “having”, “containing”, “including”, “comprising”, and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.
The above description is illustrative and not restrictive. Many variations of the invention will become apparent to those of skill in the art upon review of this disclosure. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.
While the present invention has been described in connection with a series of preferred embodiments, these descriptions are not intended to limit the scope of the invention to the particular forms set forth herein. It will be further understood that the methods of the invention are not necessarily limited to the discrete steps or the order of the steps described. To the contrary, the present descriptions are intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims and otherwise appreciated by one of ordinary skill in the art.

Claims

What is claimed is:

1. A method for converting a free fatty acid into an ethyl ester form of the free fatty acid, comprising:

contacting the free fatty acid with a non-polar solvent to form a first mixture;

adding a mineral acid and an alcohol to the first mixture to form a second mixture;

heating and agitating the second mixture to form a two-phase mixture; and

removing an aqueous phase from the two-phase mixture.

2. The method of claim 1, the non-polar solvent further comprising hexane, cyclohexane, heptane, d-limonene, naphtha, xylene, toluene, pentane, cyclopentane, benzene, 1,4-dioxane, chloroform, diethyl ether, dichloromethane, methyl acetate, and mixtures thereof.

3. The method of claim 1, the non-polar solvent further comprising heptane.

4. The method of claim 1, the free fatty acid representing by weight from approximately 3% to 15% of the first mixture.

5. The method of claim 1, the alcohol further comprising methanol, ethanol, propanol, butanol, pentanol, and mixtures thereof.

6. The method of claim 1, the alcohol further comprising ethanol.

7. The method of claim 6, the ethanol representing by weight from approximately 3% to 20% of the second mixture.

8. The method of claim 1, the mineral acid further comprising sulfuric acid, hydrochloric acid, perchloric acid, boron trifluoride, and mixtures thereof.

9. The method of claim 1, the mineral acid further comprising sulfuric acid.

10. The method of claim 9, the sulfuric acid representing by weight from approximately 0.4% to 5% of the second mixture.

11. The method of claim 1, further comprising the adding sulfuric acid and ethanol to the first mixture in presence of water.

12. The method of claim 11, the water representing by weight from approximately 0.1% to 10% of the second mixture.

13. The method of claim 1 further comprising heating the second mixture to between approximately 50° C. to approximately 100° C. for approximately one hour.

14. The method of claim 1 further comprising stopping the agitating prior to the removing of the aqueous phase.

15. The method of claim 1 further comprising removing the aqueous phase while agitating the second mixture.

16. The method of claim 15 further comprising removing the aqueous phase using a centrifuge.

17. The method of claim 15 further comprising removing the aqueous phase using an extractor.

18. The method of claim 17 further comprising heating and agitating a remaining solution formed by the removing of the aqueous phase.

19. The method of claim 1 further comprising the free fatty acid being produced by an algal genus.

20. The method of claim 19, further comprising the algal genus comprising one or more of Amphora, Anabaena, Anikstrodesmis, Botryococcus, Chaetoceros, Chlorella, Chlorococcum, Cyclotella, Cylindrotheca, Dunaliella, Emiliania, Euglena, Glossomastix, Haematococcus, Isochrysis, Monochrysis, Monoraphidium, Nannochloris, Nannochloropsis, Navicula, Nephrochloris, Nephroselmis, Nitzschia, Nodularia, Nostoc, Oochromonas, Oocystis, Oscillatoria, Pavlova, Phaeodactylum, Picochloris, Platymonas, Pleurochrysis, Porphyra, Pseudoanabaena, Pyramimonas, Scenedesmus, Stichococcus, Synechococcus, Synechocystis, Tetraselmis, Thalassiosira, and Trichodesmium.

21. The method of claim 1, further comprising producing a free fatty acid composition comprising by dry weight approximately 10% to approximately 99% C16:1 n7 palmitoleic acid and less than approximately 20% saturated fatty acids.

22. The method of claim 1, further comprising a free fatty acid composition comprising by dry weight approximately 10% to approximately 99% C20:5 n3 eicosapentaenoic acid and less than approximately 10% saturated fatty acids.

23. A method for converting a free fatty acid into an ethyl ester form of the free fatty acid, comprising:

contacting algal oil containing free-fatty acids with a non-polar solvent to form a first mixture, the algal oil representing by weight from approximately 3% to 15% of the first mixture;

adding sulfuric acid and ethanol to the first mixture to form a second mixture, the sulfuric acid representing by weight from approximately 0.4% to 5% of the second mixture, and the ethanol representing by weight approximately 3% to 30% of the second mixture;

heating and agitating the second mixture to form a two-phase mixture; and

removing an aqueous phase from the two-phase mixture.

24. The method of claim 23, the non-polar solvent further comprising hexane, cyclohexane, heptane, d-limonene, naphtha, xylene, toluene, pentane, cyclopentane, benzene, 1,4-dioxane, chloroform, diethyl ether, dichloromethane, tetrahydrofuran, methyl acetate, and mixtures thereof.

25. The method of claim 23 further comprising heating the second mixture to between approximately 50° C. to approximately 100° C. for approximately one hour.

26. The method of claim 23 further comprising stopping the agitating prior to the removing of the aqueous phase.

27. The method of claim 23 further comprising removing the aqueous phase using a centrifuge.

28. The method of claim 23 further comprising removing the aqueous phase using an extractor.

29. The method of claim 23 further comprising the free fatty acid being produced by an algal genus.

30. The method of claim 29, further comprising the algal genus comprising one or more of Amphora, Anabaena, Anikstrodesmis, Botryococcus, Chaetoceros, Chlorella, Chlorococcum, Cyclotella, Cylindrotheca, Dunaliella, Emiliania, Euglena, Glossomastix, Haematococcus, Isochrysis, Monochrysis, Monoraphidium, Nannochloris, Nannochloropsis, Navicula, Nephrochloris, Nephroselmis, Nitzschia, Nodularia, Nostoc, Oochromonas, Oocystis, Oscillatoria, Pavlova, Phaeodactylum, Picochloris, Platymonas, Pleurochrysis, Porphyra, Pseudoanabaena, Pyramimonas, Scenedesmus, Stichococcus, Synechococcus, Synechocystis, Tetraselmis, Thalassiosira, and Trichodesmium.