fats and oils quality, characteristics, extraction and refining · pdf file ·...

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

mailto:[email protected]

March 16, 2010 Presentation Prepared For: Farm

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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.”


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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.


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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.


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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…


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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 AOCS Tr 1a-64 T 31 C Min.

Free Fatty Acid AOCS Ca 5a-40 15% Max.

FAC Color AOCS Cc 13a 39 Max.

M.I.U. 2% Max.

Moisture AOCS Ca 2c-25 1% Max.

Insoluable AOCS Ca 3a-46

Unsaponifiable AOCS Ca 6a-40

• Information from Darling International


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Biodiesel - ASTM D6751 Specification

Example


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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


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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.


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Fats and Oils Molecular Composition

• Animal fats and vegetable oils are triglycerides. They consist of

three fatty acids attached to a glycerin backbone.

• Oils tend to contain more unsaturated fatty acids.

• Fats contain more saturated fatty acids.


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Fatty Acids Molecular Composition


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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.


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Soybean Oil Composition


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Fatty Acid Profiles of Various Triglycerides

Weight % of Fatty Acids in Fats and Oils


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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.


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Typical Oil Contents

Oil Bearing Material Oil Content %

Canola 40 to 45

Coconut 65 to 68

Corn 3 to 6

Cottonseed 18 to 20

Olive 25 to 30

Palm 45 to 50

Peanut 45 to 50

Safflower 30 to 35

Soybean 18 to 20

Sunflower 35 to 45


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Hard Press Extraction• Procedure

– 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.


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Solvent Extraction

• Procedure– 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.


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Recovered “Crude” Oil• Contents of recovered crude oil

– 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


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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


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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:


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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.


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Process Flow Diagram


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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)– Temperature

– Acid and Caustic Concentrations

– Agitation Rate

– Dwell Time

• Quality (Determined by the skill of the process operator)– See the next Slide


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Soybean Oil Composition


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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

mailto:[email protected]

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