Processing of Crude Algal Oils and Production of EPA and DHA Concentrates
Rick Green, Ph.D.
POS Bio-Sciences
Saskatoon, SK
BIO Pacific Rim Summit
December 8, 2014
Overview of POS Bio-Sciences
• POS is a fee-for-service technology
development organization.
• Specialize in process development for
ingredients along with globally recognized
analytical services.
• Extraction and isolation of components from
plant and microbial sources.
• Extensive experience in algal oil processing
and fractionation to produce EPA and DHA
concentrates.
• Manage a multi-scale processing facility.
• 38 year technology development history.
Overview of POS Bio-Sciences
New process/product concept
Laboratory
(2 kg)
Mini-pilot scale trials
(20 kg)
Pilot scale development
(200 kg - Tonnes)
Custom manufacturing
(10 T – 600 T)
Commercial production
Components of Extracted
Microalgae Crude Oil
Lipids*
• Neutral
• Triacylglycerols (TAG)
• Unsaturated (including n-3)
• Saturated
• Hydrocarbons
• Sterols
• Waxes
• Pigments – chlorophyll, astaxanthin
• Tocopherols
• Polar
• Phospholipids
• Glycolipids
• Free fatty acids
Elements
• S, Cl, Na, heavy metals
* Some components
beneficial, some not.
Non-lipid components
• Undesirable Contaminants
• Oxidized compounds
• Pesticide residues
• Proteins/peptides
• Polysaccharides
• Sugars
• Moisture
• Further processing of crude oils is required to remove the
objectionable components – can have significant effect on yields.
Components of Extracted
Microalgae Crude Oil
Purification and Fractionation of
Microalgae Oil
• Increase stability of the oil
• Purify for further processing
• Increase functionality of the oil
• Produce valuable co-products
• Enhance economic viability
Co-products
• Generally, co-products for functional foods,
nutrition and health benefits are higher in
value
• E.g. astaxanthin, EPA, DHA
Downstream Processing Flow for Oil and
Co-products from Microalgae
Microalgae
Concentrated
unsaturated fraction
(DHA, EPA)
Crude Oil
Refined oil,
Saturates
Meal
feed
food ing.
fertilizer
protein
carbohydrates
pigments,
antioxidants,
antimicrobials
(Should be processed
under heavy N2)
Crude oil
Degumming
Alkali-refining
BleachingDeodorization
AO fortification &
Packaging
Water washing
Fractionation
Processed oil
Omega-3 rich
fraction
Waxes, polar cmpds.
Phospholipids & Glycolipids
Free Fatty acids (as soaps)
Pigments,
elements
n-3 Oil
Microalgal Oil Processing Schematic
Wash or Trisyl Treatment Trace soaps
Water washing
• Crude oil with 15% (w/w) warm water (~55-60°C under N2).
• Centrifuge (at ~55-60°C) – separation of water and oil phases.
Target:
To remove – Sugars
Polysaccharides
Fines
Mucilaginous compounds
Proteins, etc.
Avoid if oil is high in polyunsaturates
Water Washing
Crude Algal Oil
Desludger
Hydratable gums – water degumming
Non-hydratable gums – acid degumming
• Oil is mixed with water (2% w/w) or acid (0.2% w/w) & water (2% w/w)
Acid: Citric or Phosphoric acid.
• Centrifuge: gives semi-solid gum phase and liquid oil phase
(degummed oil).
Washed Oil
Degumming
• First step of the refining process, designed to remove
phosphatides (gums) that interfere with subsequent processing.
Alternative to Degumming
• Mixing the oil in acetone will cause precipitation of the polar lipids
(phospholipids and glycolipids)
• Need to use explosion proof equipment and a solvent rated facility
• A more expensive method
Precipitation of Polar Lipids in Acetone
Degummed oil
• Involves the removal of free fatty acids (FFA)
• Sufficient caustic is added to convert the FFA to soaps (FFA salts) –
these are water insoluble.
• Calculate the required amount of caustic (dilute NaOH solution or
Baumé) based on free fatty acid content.
• Required amount of caustic mixes with degummed oil at 60C for
minimum of 30 min.
• Centrifuge at 70°C to separate soap and liquid-oil phase
(alkali-refined oil).
Alkali Refining
Continuous
Refining Separator
Alkali RefiningFFA Soaps
OH-C-R + KOH
O
K+-O-C-R + H2O
O
Alkali-refined oil
• Trisyl - an amorphous, synthetic silica hydrogel used to remove small
amounts of soaps formed during alkali refining of the oil.
(in lieu of water washing)
• Due to the polar nature of Omega-3 containing Algae oil, water washing
is not suitable for removing soap (yield losses may be very high).
• Calculate the required amount of Trisyl, based on the remaining soap.
• Trisyl mix with refined oil at 60°C for ~30 min.
• Filter using frame filters to separate soap adsorbed Trisyl-solids
and Trisyl-treated oil.
Trisyl Treatment
Bleaching
• Oil is mixed with an adsorptive clay to remove pigments
(e.g. chlorophyll) and elements/metals.
• Also removes some breakdown products of any fatty
acid/TAG oxidation (e.g. peroxides, ketones)
Filter PressReactor for bleaching
Trisyl treated oil
Deodorization
Continuous Column Deodorizer
(250 kg/hr)
Column packing
Remove odors and flavors from high oils/fractions.
Bleached oil
Fractionation of Oil & Production of
DHA & EPA Concentrates
Dr. Udaya Wanasundara
Principal Scientist
Lipids & Co-Products
Low temperature crystallization (in solvent)
Urea Adduct Formation
Short Path Distillation/Fractional Distillation
Supercritical fluid extraction & fractionation
Chromatographic separation (CPC, HPLC)
Esterification is usually required prior to the concentration
All these methods have advantages and disadvantages
Important consideration should be product quality and the cost of production
Methods for Concentration of Omega-3 Fatty Acids
Fatty Acid Melting point (C)
Melting point of a FA depends
on the chain length and the
number of double bonds
(unsaturation) present.
Saturates – high MP
PUFA – low MP
Low Temperature Crystallization
Example Conditions
• Algae oil (TAG or FFA)
• Solvents: Hexanes or Acetone
• Oil-to-solvent ratio: 1:4 (w/v)
• Temperature: -25oC
• Time: 24h with slow mixing
• Separate crystals by filtration
• Evaporate solvent from liquid
fraction (non-crystallized
fraction)
Low Temperature Crystallization
Non-crystallized fraction
(PUFAs)
Crystallized fraction
(Saturated fatty acids)
Jacketed Tank
Enrichment of PUFAs by Low Temperature Crystallization
AcetoneHexanes
12.0
15.1
37.2
TAG
8.2
10.1
27.8
TAG
13.8
17.5
40.6
11.8
12.5
31.6
6.8
8.4
22.2
EPA (%)
DHA (%)
Total 3 (%)
FFAFFA
Starting
Marine
Oil
Fatty Acid
Esters
Urea Adduct Formation
5.67Å
CO
HN2 HN2
FFA/EE
mixture
Urea:CO(NH2)2
(Tetragonal)
Urea & Straight Chain
Molecules (Hexagonal)
PUFA
(NUCF)+
UCF
8-12ÅFA
• In a FFA or ethyl ester
(EE) mixture, saturates
and mono-unsaturates
are complexed with urea
(UCF).
• Presence of double
bonds increases the
bulk of the molecule and
reduces the likelihood of
its complexation with
urea, i.e. PUFAs remain
in the liquid and are
referred to as non-urea
complexing fraction
(NUCF).
• Dissolve urea in 95% ethanol or methanol.
• Add either FFA or Ethyl ester form of Omega-3 rich oil
• Mix and leave at room temperature or ~4C to form crystals (Urea/fatty acid complex or adduct).
During crystallization, straight saturated and mono-unsaturated fatty acids are form complex with urea (Urea Complexed Fraction, UCF) and PUFAs remain in the liquid (Non-Urea Complexed Fraction, NUCF).
• Solid UCF (with saturates and mono-unsaturates ) and liquid NUCF (with PUFAs)
can be separated by filtration.
Urea Adduct Formation
Enrichment of EPA- and DHA-EE by Urea Method
6.8 4.2 8.4
10.9 2.4 67.6
3:1
57.1
98.8
4:1
Starting oil
After urea
Urea-to-EE Ratio(w/w)
Marine
EPA DPA DHA
Algal
DHA
Values are in w/w%
Short Path Distillation
• Uses the differences in boiling point and
molecular weight of fatty acid esters
• Saturated short chain acid-esters – lower
boiling point and more volatile than long
chain high MW fatty acid-esters, such as
PUFA.
• Distillation of fatty acid esters is carried out
under vacuum (0.1-4.0 mmHg)
• Distillation temperatures (150-210oC).
Fractionation
Short Path Distillation
• Fractionation of oils, waxes• Preparation of value-added fractions (e.g. Omega-3 rich concentrates)
Short Path Distillation of 3 Fatty Acid-Ethyl Esters
11.8
12.2
26.2
53.1
23
11.8
7.0
15.5
38.2
50
7.0
4.2
8.8
23.2
EPA-EE
DPA-EE
DHA-EE
Total 3-EE
Yield (%)
Trial-2Trial-1Starting Algal Oil Esters Fatty Acid Esters
(%)
Conditions Trial-1 Trial-2
Temperature (oC) 170 190
Pressure (mm Hg) 1.5 1.5
Holding Time (min) 7 7
Summary of Scale-up Processing for Microalgal Oil
• Increase purity by degumming, alkali refining, Trisyl
treatment, bleaching and optionally deodorizing.
• Prepare DHA and EPA concentrates by fractionation of
the refined oil.
• Viable large scale fractionation techniques include low
temperature crystallization, urea adduct formation and
fractional distillation (short path distillation).
Thank You!POS Bio-Sciences118 Veterinary RoadSaskatoon, SKCANADA S7N 2R4
Tel. (306) 978 2800
email: [email protected]