Ozan N. Ciftci, Ph.D.Department of Food Science and Technology

University of Nebraska-LincolnLincoln, NE, United States

Realizing integrated supercritical fluid biorefineries for green processing of grains

and oilseeds

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There is a growing demand for green extraction of lipids

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Supercritical Carbon Dioxide (SC-CO2) Extraction

A green technology with a bright future and many opportunities

Fluid above its critical pressure and temperature.

Liquid-like density to enhance solubility, gas-like viscosity, compressibility and diffusivity, allowing higher mass-transfer rates or penetration.

7.4 MPa

Cheap, non-toxic, abundant. Moderate critical pressure and

temperature (31 °C, 7.4 MPa). Ease of separation from solute. No solvent residue in products. Environmentally friendly process. No oxidation in CO2 environment. No degradation of heat labile

components. “Clean” products.

31 °C

SC-CO2: A green fluid with many advantages

31 °C/74 barAtmospheric

conditions

SOLUTION Taking full advantage of benefits of SC-CO2processing

HOW? Integrated SC-CO2 processing as part of a biorefinery

SC-CO2 extraction of specialty oils

SC-CO2 extraction of commodity oils

Issue with SC-CO2 Extraction of Commodity Oils

SC-CO2ExtractionLipid-rich

Grain/oilseedOil

Potential use of SC-CO2 processing in an integrated biorefinerySC-CO2 extraction of oils

SC-CO2Extraction

Separations

SC-CO2Fractionation

SC-CO2Bio/Reaction

SC-CO2 Particle Formation

Lipid-rich Grain/oilseed

Bioactives(minor lipids)

SC-CO2 + lipidMeal

Protein isolates

Carbohydrate fractions

Micro/nano particlesEncapsulates

OilOleochemicals

Biofuels

Potential use of SC-CO2 processing in an integrated biorefinery

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Potential use of SC-CO2 processing in an integrated biorefinery

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SC-CO2 extraction as part of a SC-CO2 biorefinery: Three case studies

Lipid-rich feedstock

Animal feed

Nutraceuticals: carotenoids, tocols, phytosterols

Residue: carbohydrates and proteins

Biodiesel

Corn DDGS: Real value of DDGS is underestimated

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Abundant inexpensive by-product of ethanol plants

~ 12% of oil High value minor lipid components: carotenoids, tocols and phytosterols

Contains high value components

Not used as food

SC-CO2 extraction

Residue

Lipids (9.2%)

Corn DDGS(11.2% oil)

Conversion to biodiesel

SC-CO2 extraction of lipids from corn DDGS

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Particle formation

35-50 MPa50-70 °C

Content of bioactive lipid compounds in the hexane- and SC-CO2-extracted DDGS lipids

Ciftci O.N., Calderon J., Temelli F. (2012). Journal of Agricultural and Food Chemistry, 60, 12482-12490.

SC-CO2 Processing of Distillers Grains

SC-CO2Extraction

DDGS SC-CO2 bioreactor

Fatty Acid Methyl Esters (FAME)

(Biodiesel)Lipids

Proteins(zein)

Separations SC-CO2 Particle Formation

Bioactives(carotenoids, tocols, phytosterols)

Functional food ingredients/

nutraceuticals

Meal

Product

DDGS lipid and methanol mixture

OvenSubstrate pump

CO2 pump

Temperature controller

SC-CO2 bioreactor to convert corn DDGS lipid into biodiesel

Immobilized enzyme column

Lipase from Candida antarctica,immobilized on macroporous acrylic resin, >10,000 U/g)

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CO2 cylinder DDGS lipid andmethanol mixture

CO2 Pump

Packed bed enzyme reactor

High pressure pump

Micrometeringvalve

Product

Oven

a

Depressurizing valve

Flowmeter

Back Pressure Regulator

Pressure gauge

Check valve

Mixer

Temperature controllerRupture disc

Flow diagram of the continuous SC-CO2 bioreactor

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Conversion for corn DDGS lipids at optimized conditions of the model system

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Enzyme load (g)

Cont

ent (

wt. %

)

0

20

40

60

80

100FAME MAG DAG TAG Glycerol

0.5 1 1.5 2

Ciftci O.N., Temelli F. (2013). Biomass and Bioenergy, 54, 140-146.

P= 19.4 MPaT= 63 oCMethanol to corn oil mole ratio= 7

Optimized conditions:

Ciftci O.N., Temelli F. (2011). Journal of Supercritical Fluids, 58, 79-87.

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Processing other DDGS sources

Extensive purification is not necessary. No water is used, no wastewater is generated.

Ciftci O.N., Temelli F. (2013). Bioenergy Research, 7, 702-710.

CO2

Methanol

Corn oil

Ambient 3 MPa 7 MPa

11 MPa 20 MPa 35 MPa

T= 55 °C

Oil and methanol are immiscible at ambient conditions: low conversions But they are miscible in the presence of SC-CO2 Expanded substrates have better mass transfer properties

Why high yields in SC-CO2?

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SC-CO2 Extraction-Particle Formation

SC-CO2Extraction

DDGS SC-CO2 bioreactor

Fatty Acid Methyl Esters (FAME)

(Biodiesel)Lipids

SC-CO2 Particle Formation

Bioactives(carotenoids, tocols, phytosterols)

Functional food ingredients/

nutraceuticals

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Particle formation using SC-CO2

Nanoporous starch aerogels

SC-CO2 Extraction

Bioactive-loaded hollow solid lipid micro- and nanoparticles

Protein nanoparticles encapsulating bioactives

Bioactive impregnated nanoporous starch aerogels

Solid lipids

Proteins

Polysaccharides

Atomization of SC-CO2-expanded lipids

Bioactives/minor lipids from SC-CO2extraction

Bioactive-loaded free-flowing hollow solid lipid micro- and nanoparticles

Natural food antimicrobials

Functional food ingredients and nutraceuticals

Yang J., Ciftci, O. (2016). Food and Bioproducts Processing, 98, 151-160.Yang J., Ciftci, O. (2016). Food Research International, 87, 83-91.

Yang, J., Ciftci, O. (2017). Food Chemistry, 231, 105-113.

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SC-CO2 Extraction-Separation-Particle formation

Supercritical Antisolvent (SAS) Process

Functional food ingredients and nutraceuticals

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A model green integrated wheat biorefinery

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2.5-10% EtOH

Unique extract compositions can be obtained by SC-CO2extraction: Camelina sativa seed lipids example

35-40% of α-linolenic acid (C18:3 ω3, ALA).

Total polyunsaturated fatty acid (PUFA) content of > 55%: susceptible oxidation.

Ethanol-modified SC-CO2 extraction can increase oxidative stability of highly unsaturated oils

Belayneh, H.D., Wehling R.L., Cahoon E., Ciftci, O. (2017). Journal of Food Science, 82, 632-637.

Ethanol-modified SC-CO2 can selectively extract phospholipids

Belayneh, H., Wehling, R., Cahoon, E., Ciftci, O. (2017). Food Chemistry, 242, 139-146.

Soy lecithin emulsion

Camelinalecithin emulsions

Not only does SC-CO2 extract lipids, but it can be used to modify the structure of lipophilic bioactives

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Cis-lycopenes

Real value of tomato byproducts is underestimated

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30 million tons worldwide

Rich in carotenoids: lycopene >90%

Waste or animal feed

~40% byproducts

Lycopene: A high value product used in food, pharmaceutical, and

cosmetic industry

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A powerful antioxidant (Boileau et al., 2002)

Protects against:• Heart disease (Rao and Agarwal, 2000)

• Risk of stroke (Rao and Agarwal, 2000)

• Raised cholesterol levels (Ried and Fakler 2011)

Protects against some types of cancer: • Prostate (Giovannucci et al., 1995)

• Lung and stomach (Guttenplan et al., 2001 )

Anti-inflammatory effect (Palozza, P. et., al 2010)

Health Benefits of Lycopene

Lycopene isomers

30http://www.cmaj.ca/content/163/6/739/F1.expansion.html

Plant sources: 95% of all trans-lycopene

cis-isomers represent 50-80% in blood and prostate tissues (Longo et al., 2012)

Higher bioavailability (Boileau et al., 2002)

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Highest lycopene content

Different capital letters represent significant differences among the peel:seed blend groups at the same extraction conditions (p<0.05) , and different small letters represent significant differences within the same the

peel:seed blend group (p<0.05).

Total lycopene content of the tomato byproducts oleoresins

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34% cis-lycopeneHexane

Trans- and cis-lycopene content of the tomato byproducts oleoresins

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SC-CO230 MPa/40 °C

34% cis-lycopene 67% cis-lycopene

Trans- and cis-lycopene content in tomato byproducts oleoresins

SC-CO230 MPa/80 °C

34% cis-lycopene

SC-CO250 MPa/40 °C

56% cis-lycopene

SC-CO250 MPa/80 °C

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Trans- and cis-lycopene content of the oil and insoluble fractions of the tomato peel oleoresin

82% cis-lycopene26% cis-lycopene

76% cis-lycopene38% cis-lycopene

SC-CO2 at 30 MPa/80 °C SC-CO2 at 50 MPa/80 °C

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Bioaccessibility

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Challenges & Future OutlookLack of knowledge on fundamentals of integration and cost analysis.Technical limitations: no real continuous extraction system is available.Partnering with the manufacturers of the materials (e.g., membranes, enzymes, reactors, etc.) used in the supercritical operations.Integration of supercritical operations with conventional technologies for efficient and optimal process design.

Thank you

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