Fats and Oils Quality,
Characteristics, Extraction and
Refining Overview
Prepared By:
Ralph Turner, P.E.
email
Prepared For Presentation To:
Farm Energy Conference, Manchester NH
March 16, 2010
Resume
• Registered Professional Engineer
– 25 Years in Energy Related Fields - Design and Construction
• 10 Years in Energy Conservation
• 10 Years in Alaska Petrochemical
• 5 years in Biodiesel nationwide
– Owner‟s Technical Representative on the design and construction of a
45,000,000 gpy Biodiesel Plant in Erie, PA
• Co-Owner Laughing Stock Farm
– 12 Acre Certified Organic Mixed Vegetable Farm Located in
Freeport, Maine.
– Developed Triglyceride Burner Fuel system for heating 12,500 sf
of Greenhouses.
– Winter growers of specialty vegetables – vegetables grown year
„round since 2003 using triglyceride burner fuel for heat.
– Chair ASTM Sub “P” Working Group “Standard Specification for
Triglyceride Burner Fuels.”
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
2
Preface
• Historically meal (for human and animal food), lecithin,
tocopherols, and food grade fats and oils have been the
primary economic drivers of production.
• Until recently fats and oils have been in surplus, and
considered a relatively low value byproduct.
• Only recently have energy uses of fats and oils begun to
be economically viable.
– Food value of fats and oils is still far above the energy value of
fats and oils.
– Industrial and technical value of fats and oils is still above the
energy value of fats and oils.
– Animal feeds value of fats and oils tends to remain below the
energy value of fats and oils.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
3
Fats and Oils Quality
“Oil Quality” is the physical and
chemical properties of fats or oils that
are necessary for any specific
purpose as stated in a product
specification or certificate of analysis.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Measurement of Fats and Oils
Quality
• Organizations that maintain standard
specifications and test methods:
– American Oil Chemist Society (AOCS)
– Fats and Protein Research Council (FPRC)
– National Renderers Association (NRA)
– American Society for Testing Materials
(ASTM)
– Proctor and Gamble…
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
5
Yellow Grease Specification (Example)
• Yellow grease is made up of restaurant greases (fats and
oils from cooking). Another source could be from
rendering plants producing lower quality tallow.
• Yellow Grease Specs - Guaranteed Analysis:
Titer
Free Fatty Acid
AOCS Tr 1a-64 T
AOCS Ca 5a-40
31 C Min.
15% Max.
FAC Color
M.I.U.
Moisture
Insoluable
Unsaponifiable
AOCS Cc 13a
39 Max.
2% Max.
1% Max.
AOCS Ca 2c-25
AOCS Ca 3a-46
AOCS Ca 6a-40
• Information from Darling International
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
6
Biodiesel - ASTM D6751 Specification
Example
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Major Factors Affecting Oil Quality
• Pre-Process Factors
– Growing Season – Temperature, Moisture, Sunlight.
– Soil Fertility and Nutrients.
– Post Harvest Storage Conditions - Temperature,
Moisture, etc.
• Post-Process Factors
– Heat - Thermal degradation from pressing or cooking.
– Moisture - Hydrolysis from contact with water in
pressing, cooking, and storage.
– Air Contact - Oxidation from contact with air during
pressing, cooking, and storage
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
8
What Makes It A Fat Vs. An Oils
• Fats and Oils include all vegetable and
animal oils and fats.
– Per the American Oil Chemist Society
(AOCS) the definition of an oil is a triglyceride
that is mostly liquid at 68 deg F. A fat is
mostly solid at 68 deg F.
• Some common examples include:
– Cooking oils like soy, canola, and corn oil.
– Edible fats like some tallow and lard.
• Some less common examples include:
– Choice white, yellow, and brown grease.
– Non-edible rendered animal fats.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
9
Fats and Oils Molecular Composition
• Animal fats and vegetable oils are triglycerides. They consist of
three fatty acids attached to a glycerin backbone.
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Oils tend to contain more unsaturated fatty acids.
Fats contain more saturated fatty acids.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Fatty Acids Molecular Composition
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Free Fatty Acid
• Free fatty acids are the single most important contributor
to quality degradation in fats and oils.
• Fatty acids are “acids” because they meet the
Bronsted/Lowry definition of an acid as a compound
which donates a hydrogen ion (H+) to another
compound called a base.
• When fatty acids dissociate from the glycerin backbone
exposing the hydrogen ion (radical) they become “free
fatty acids.”
• Because of the activity of the hydrogen ion (radical) and
the weak double carbon bonds, free fatty acids readily
combine and recombine in unpredictable and indefinable
ways to form extremely complex polymer networks.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
12
Soybean Oil Composition
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Fatty Acid Profiles of Various Triglycerides
Weight % of Fatty Acids in Fats and Oils
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Oil Extraction
• Primary Oil Recovery Methods
– Hard Press Extraction
• Pros – Low capital cost, small scale, provides high oil meal
for niche cattle feeds.
• Cons – poor oil and meal quality, high energy input, low
recovery efficiency, not suitable for low oil content seed, high
oil meal is detrimental for poultry feeds.
– Solvent Extraction
• Pros – High quality oil and meal, low energy input, high
recovery efficiency
• Cons – High capital cost, high system complexity, higher
environmental risk.
– Rendering – only used for animal fats and not
discussed here.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Typical Oil Contents
Oil Bearing Material
Canola
Coconut
Corn
Cottonseed
Olive
Palm
Peanut
Safflower
Soybean
Sunflower
March 16, 2010
Oil Content %
40 to 45
65 to 68
3 to 6
18 to 20
25 to 30
45 to 50
45 to 50
30 to 35
18 to 20
35 to 45
Presentation Prepared For: Farm
Energy Conference
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Hard Press Extraction
• Procedure
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Seed (or beans) are dried (post harvest) for storage.
Dried seed is preheated.
Preheated seed is fed to press.
Feed preheat, pressure, and press temperature are balanced for
optimal oil removal. Heat removal is necessary for optimal
quality.
Cake is recovered in bins.
Oil flows to sediment basin.
Sediment (foots) are returned to press.
Crude Oil is filtered and pumped to storage.
• Quality
– Optimal cake quality is 3-4% oil content.
– Typical small scale cake quality is 6-10% oil content.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Solvent Extraction
• Procedure
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Seeds (or beans) are dried (post harvest) for storage.
Dried seed is “crushed”, “conditioned” and “flaked.”
Flake is fed into the extractor.
Solvent is percolated through flake.
Miscella (solvent oil mixture) is collected in the sump.
Solvent is recovered by distillation to a separate
vessel.
– Meal and oil are transferred to storage.
• Quality
– Typical cake quality is 0.5 to 1% oil content.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Recovered “Crude” Oil
• Contents of recovered crude oil
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March 16, 2010
Triglycerides
Free fatty acids
Gums of phospholipids
Crude lecithins
Metal complexes; iron, copper, calcium, magnesium
Peroxides and degradation polymers
Color pigments
Sterols,
Tocopherols
Meals
Waxes
Moisture
Dirt
Presentation Prepared For: Farm
Energy Conference
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Crude Oil Treatment
• Edible fats and oils are usually designated
as RBD and treated as follows:
– Refining
• Removal of Phosphatides (degumming)
• Neutralization and removal of FFA
• Removal of minor components.
– Bleaching – Not normal for fuels
• Removal of colors
– Deodorizing – Not normal for fuels
• Removal of aromatics objectionable to end user
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
20
Degumming
• Crude oils contain phosphatides in two forms:
– nonhydratable phosphatides (NHP)
– hydratable phosphatides (HP)
• Degumming is the treatment of crude oils with dilute acid
solutions and water to remove phosphates, waxes, and
other impurities that tend to settle over time and clog
piping, pumping, and control systems.
– A dilute acid treatment is used to convert the nonhydratable
phosphatides to hydratable phosphatides.
– Water is added to convert the hydratable phosphatides to
hydrated gums which are insoluble in oil and readily separated
as sludge by settling, filtering, and centrifuge.
• Degumming is followed by Caustic Refining as described
below:
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Caustic Refining
• The addition of a dilute alkali solution to
bring about chemical and physical
reactions that assist in the removal of
unwanted constituents of the crude oil.
– Alkali combines with FFA to make soaps.
– The gums and some remaining NHP absorb
alkali and coagulate, easing separation.
– Much of the other insoluble material is
entrained in the soaps and coagulable
material.
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
22
Process Flow Diagram
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
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Variables
• Crude Oil Variables (From growing and
storage conditions)
– FFA – Defined by Standard Test Method
– Phosphorus Levels – Defined by STM
• Process Variables (Set by the process
operator)
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Temperature
Acid and Caustic Concentrations
Agitation Rate
Dwell Time
• Quality (Determined by the skill of the process
operator)
– See the next Slide
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
24
Soybean Oil Composition
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
25
Rhetorical Question
If a farm can produce vegetable oils for fuel (which is a
relatively low value product) can a few steps be added
to allow the production of specialty salad and other
food oils (which have a very high value) to maximize
the farm revenue and profits?
In other words, regardless of whether oil is worth more
as food to society, can edible oil be worth more to the
farmer on a small local or regional scale?
Ralph Turner, PE
email
March 16, 2010
Presentation Prepared For: Farm
Energy Conference
26