Transcript Citrus Biorefinery - Washington University in St. Louis

Citrus-Based Biorefinery
- Opportunities and Challenges www.ars.usda.gov
www.praj.net
OH
Patrick L. Mills
Dept of Chemical & Natural Gas Engineering
Texas A&M University-Kingsville
Kingsville, TX 78363
[email protected]
CREL Annual Meeting – Washington University in St. Louis
Energy: From Molecular Transformations to Systems
October 25, 2006
The New Departmental Plan
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Starting References
1. B. Kamm, P. R. Gruber, & M. Kamm (editors), Biorefineries – Industrial
Processes & Products: Status Quo & Future Directions,
John Wiley: New York, ISBN 3527310274, 964 pp, April 2006.
2. R. J. Braddock, Handbook of Citrus By-Products & Processing Technology,
Wiley-Interscience: New York, ISBN 0471190241, 247 pp, 1999.
3. R. J. Braddock, “Importance of by-products to citrus juice processing,”
Fruit Processing, 5, pp 310-313 (2004).
4. Dan A. Kimball, Citrus Processing: A Complete Guide, 2nd Edition,
Chapman & Hall Food Science Series, Aspen Publishers, Gaithersburg, MD
ISBN 0834212587, 450 pp, 1999.
5. T. R. Graumlich, “Potential fermentation products from citrus processing
wastes,” Food Technology, 94-97, Dec 1983.
6. W. Q. Hull, C. W. Lindsay, & W. E. Baier, “Chemicals from oranges,”
Ind. Engng. Chem., Vol. 45, No. 5, 876-890, May 1953.
Morphology of Citrus Fruit
• 40 to 65 wt % juice
• 35 to 60 wt % waste
Orange Citrus
segment
wall
zest
Pericarp
or rind
Mesocarp or
pulp
www.infovisual.info
Nutrient Composition of Citrus By-Products
• Lipids - oleic, linoleic, linolenic, palmitic, stearic acids; glycerol & physterol
• Sugars - glucose, fructose, sucrose, galactose, xylose, rabinose, ….)
• Acids - citric, malic, tartaric, benzoic, oxalic, succinic
• Insoluble carbohydrates – cellulose, pectin
• Flavonoids, peel oil, pigments, vitamins, minerals, …
Total World Annual Citrus Production*
70 to 105 million tons/yr
Lemon
6%
C. Limon
Tangerine
18%
C. Reticulata
Minor
genuses
3%
- Sour orange
- Shaddock
- Citron
- Lime
C. Quanantium
C. Grandis
C. Medica
C. Aurantifolia
2000–2003 (avg’d)
Grapefruit
C. Paradisi
5%
USA
ROW
21%
31%
Brazil
Med 24%
24%
Sweet
Orange
68%
C. Sinensis
*USDA/FAS, 2003 Horticultural & Tropical Products Div.,Wash.,DC
Example: Florida Citrus Production*
Property
Citrus Trees, MM
Acreage
USA Production
Citrus Boxes, MM
On-Tree Value
Total Industry Value
Wet Waste, MM tons
Dry Waste, MM tons
EtOH Potential, MM gals
Amount
103
800,000
80%
287
$1 MMM
$ 9 MMM
5
1.25
120
MM = 1 x 106
*USDOE, Office of Energy Efficiency & Renewable Energy
90 lbs/box
Added Value
From Juice
By-Products
Citrus Juice Process & Material Balance
Fresh Citrus Fruit
3000 b/hr 123,000 kg/hr
33.4 %
66.6 %
Juice extractors
Citrus Juice
Wet Peel
54,600 kg/hr 82% H2O
Hammermill
Oil Mill / Plant Waste
Reaction Time
Presses
Press Liquid
35,600 kg/hr
Press Cake
19,000 kg/hr 65% H2O
Dryer Feed
25,600 kg/hr 61% H2O
Dryer
14,500 kg/hr
(Soluble Fraction)
30,000 kg/hr
d-Limonene
140 kg/hr
Molasses
6400 kg/hr 9o Brix
Molasses
4400 kg/hr 72o Brix
Waste Heat Evap
9o Brix
(Insoluble Fraction)
Pellets
11,000 kg/h 10% H2O
Process Flow for Citrus By-Products
Fresh Citrus Fruit Residue
(Ground or Chopped)
Citrus Seeds
Pressure
Ca(OH)2 added
Pressure with
Added Ca(OH)2
Press Liquor
Dehydration
Citrus Oils
Dehydrated without pressing
Citrus Molasses
Dried Citrus Pulp
with Liquor
Pressed Fresh
Pulp
Sieved
Dehydration
Dried Citrus Pulp
(w/o Molasses)
Dried Citrus
Meal
Dried Citrus Pulp
(with Molasses)
Pelleted & Added
Back to Pulp
Addition
Citrus Seed
Meal
Sold as
Molasses
Bampidis & Robinson, Animal Feed Sci. Tech. 128 (2006)
Distribution of Citrus By-Products
Basis: Oranges = 40.8 kg/box; Juice Yield ca. 55%
9.80
10
8
6
Wt % of
By-Product
(Orange Basis)
4.90
3.43
4
3.19
2
0.74
0.74
0
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ry
p
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0.49
Distribution of Orange Juice By-Products
Basis: 2005 – 2006 USA Production of 695,275 MT
Flavonoids
2%
Peel dry pellets
(10% H2O)
42%
Frozen pulp
21%
Pectin
(150 grade)
14%
Pulpwash soluble
solids
3%
Essential oil and
d-limonene
3%
Source: www.fas.usda.gov
Molasses (72
°Brix)
15%
Pectin & Pectic Acid
Pectin Molecule
Pectic Acid (D-Polygalacturonic acid)
Recovery of Pectin from Citrus Peel
Background
• Pectin (a polysaccharide) - white, spongy inner part of the peel
• Significant yield loss & waste generation with conventional hydrolysis
Opportunity
• Significant growth in use of low-methodoxyl (LM) pectin as a
- Thickening or gelling agent
- In formulated food applications (yogurt, milk, desserts, etc...)
Needs
• Method for extraction & conversion of high-methodoxyl (HM) pectin
from citrus peels with high efficeincy
• New enzyme or catalysts for rapid conversion of HM to LM pectin
• Efficient methods for purification and formulation
Citrus Peel Waste as a Bio Feedstock
• Represents ca. 40 to 50 % of citrus fruit
• Dried pellets used as cattle feed supplement
• Second to corn as a source of feed nutrients
• CaO added - neutralize & de-esterify pectin
• Diffusion controlled process w/molasses
• COM can exceed cattle feed selling price
• Contains soluble & insoluble carbohydrates
(glucose, fructose, sucrose, pectin, cellulose,
hemicelluloses w/ galacturonic acid, glucose,
arabinose, xylose, … as monomeric units)
Composition of Citrus Juice
Processing Wastes (Wet vs Dry Material)
90
Wet Material
80
70
60
Wt%
• Lower sugar content vs dry material
Composition at Minimum Water (W% )
50
Composition at Maximum Water (W% )
• Lower yield of sugars
• Lower energy consumption
40
30
20
10
0
Water
Total
Solids
Soluble
sugar
Alcohol
Insoluble
Solids
(AIS)
Crude
Fiber
Pectin
Crude
Protein
Fat
(Ether
extract)
Ash
90
• Hydrolysis of polysaccharides req’d
Dry Material
80
70
Composition at minimum AIS%
• Higher polysaccharide concentration
60
Wt%
Composition at maximum AIS%
50
• Greater potential yield of sugars
40
30
20
10
0
Soluble
sugar
Alcohol
Insoluble
Solids
(AIS)
Crude
Fiber
Pectin
Crude
Protein
Fat (Ether
extract)
Ash
• Higher energy consumption vs wet
• Higher pectin vs wet material
Composition of Alcohol Insoluble Solids
(Cell Wall Fraction of Orange Peel)*
30
Raw Materials for
EtOH Production
25
Not Useful for
EtOH Production
20
Wt %
15
10
5
W
at
er
As
h
Pr
ot
ei
n
gn
in
Li
ci
d
on
ic
A
m
os
e
Rh
a
se
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lo
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al
ac
to
se
Ar
ab
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r
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0
• Fructose & glucose present in nearly equimolar amounts
• No starch is present, unlike other Ag resids
• Some organic acids, e.g., galacturonic acid
Grohmann & Bothast, ACS Symp Ser. 566 (1994)
D-Galacturonic Acid Structure
- Formed by the hydrolysis of pectin
- Can be converted to d-glucose
Conversion of Orange Total Peel Solids
to Monomeric Sugars
- Comparison of Various Treatments-
C
CG
P
PC
PCG PCG
Conversion of total peel solids to monomeric sugars by enzymatic and combined acid and enzymatic
treatments. Left bar (Unt) of each pair represents a mean of results obtained by enzymatic treatment
alone, without acid treatment. The right bar (Tr) of each pair represents the mean of results obtained by
sequential acid and enzymatic treatment. The symbols above each pair of bars represent the enzymes (or
combination of enzymes) used in the enzymatic part of the treatment (C=cellulase; P=pectinase; bglucosidase). The last pair of bars, labeled I"PCG, represents results of a treatment with a mixture of
pectinase, cellulase and ~-glucosidase in excess. The individual sugars released are marked on the right
side of the graph (Ara=arabinose; Fru=fructose; Gal=galactose; Glc=glucose; G.A=galacturonic acid;
Xyl=xylose). Grohmann, K.; Cameron, R.G;. Buslig, B.S Bioresource Technology 54 (1995) 129-141
Products from Various Solubilization Methods
80
60
40
20
0
Suc
ros
Gluc e
o
Fruc s e
tos e
Gal a
ctos
e
Ara b
inos
e
Xylo
se
Rha
mos
e
Gal a
ct. a
cid
Tota
l Su
ga rs
Inso
l. Re
sid.
Unk
now
n
wt %
Enz
Ins y. Hy
Ins ol. So drolys
Aqu ol. So li ds (E ate o
fP
n
eou li ds
(Ac zy. Hy eel
sE
id H
xtra
d
ydr rolyze
ct
oly
zed d)
)
Enzymatic Hydrolysis of Orange Peel
Enzymatic w/dilute
acid pretreatment
Enzymatic w/o acid pretreatment
Conversion of total peel solids to reducing sugars during enzymatic hydrolysis of
untreated orange peel ( ...... ) and peel pretreated with 0-06% sulfuric acid at pH=2.0 at
100, 120 and 140°C for 10 min, respectively. Treatments: a No acid pretreatment;---<> .
pH=2-0, 100°C, 10 min; ---o . . . . pH=2.0, 120°C, 10 min; - - - + . . . . pH=2.0, 140°C, 10
min.. Grohmann, K.; Cameron, R.G;. Buslig, B.S Bioresource Technology 54 (1995) 129141
Effect of Particle Size on
Enzymatic Hydrolysis of Cellulose
Attrition mill
SS beads
Glass beads
conv. ball milling
w/o milling
Comparison of shake-flask and attrition methods for enzymatic hydrolysis of
Whatman CF-11 cellulose. (  ) Unmilled control, () ball milled, () 60 g of
glass beads, ( ) 136 g of stainless-steel beads, all with a shaker speed of 200
opm. () Attrition at 200 rpm. Cellulase complex PP 158: 1 IU/mL and 2%
substrate. Neilson M. J., Kelsey, R. G ., and Shafizadhe F (1982).
Biotechnology and Bioengineering, Vol. XXIV, pp. 293-304
Novel Hydrolysis Schemes of Citrus Peel
Background
• Peel celluose & hemi-cellulose contain value-added glucose, sucrose,..
• Existing hydrolysis methods are slow (on the order of days)
• Lack of basic understanding of hydrolysis kinetic-transport effects
Opportunity
• Develop methods and process with significantly higher
conversion rates and selectivities to monomeric sugars
Needs
• Novel enzymes, catalysts, and reactor systems
• Basic data on the reaction mechanism & kinetic-transport effects
• Mathematical models for kinetics, transport, & reactor systems
Production of Orange Juice By-Products
Basis: 2005 – 2006 USA Production of 695,275 MT
294.3
300
1 X103 Metric Tons
250
200
150
123.9
100
62.0
50
43.4
40.3
9.3
9.3
6.2
0
Dry pellets Molasses
(10% H2O) (72 °Brix)
Essential
oil and dlim onene
Source: www.fas.usda.gov
Pulpw ash Pectin (150
soluble
grade)
solids
Frozen
pulp
Flavonoids
Total
Catalytic Oxidation of Limonene
w/o LiCl
with LiCl
OH
+
O2
PdCl2 / CuCl2
or
HOAc
15 hr, pH = 6
OAc
a-terpinyl acetate
trans-carveol
R-Limonene
OOt-Bu
OOt-Bu
PdCl2 / CuCl2
+
O2
tert - BuOH
+
tert – BuOOH (aq.)
R-Limonene
tert-butyl peroxide derivatives
Oxdn of Limonene - Product Distribution
a. Conventional Wacker
OAc
OAc
O
OH
OAc
1
2
5
4
3
6
OH
b. Wacker with t-BuOH & t-BuOOH
OH
OH
OH
7
5
O
OH
8
4
CHO
9
OOt-Bu
OOt-Bu
OOt-Bu
OH
10
11
12
13
14
Functionalized Derivatives of D-Limonene
Background
• Limonene & other mono-terpenes are recovered from citrus peel oil
• Derivatives (alcohols, aldehydes, ketones, allylic ethers, carboxylic
acid esters, epoxides…) are useful in pharma, perfumery, flavors
Opportunity
• Limited literature exists on application to natural products
• Synthesis of new molecules, specialty polymers, & materials
Needs
• New organometallic catalysts for mono-terpene functionalization
• Fundamental studies on kinetics, mechanisms, multifunctional reactors
• Novel multiphase microreactor system designs & mini-plants
Example of a Flavonoid - Diosmetin
• A human CYP1A enzyme activity-inhibiting natural flavonoid.
• Diosmetin has antimutagenic and anti-allergic behavior.
Flavones & Flavonoids
• Naturally occurring aromatic secondary
plant metabolites
• > 4000 have been identified in plants
• Positive health benefits
- antioxidants
- cardioprotective
- antiviral
- anticarcinogenic
- antiallergenic
• Amount & type depends on citrus genus
and agricultural growth factors
Novel Sepn & Conversion Methods for By-Products
Background
• By-products (lignin, protein, limonene..) are produced in various
parts of the existing citrus process (hydrolysis, milling, etc.)
• Some behave as enzyme inhibitors, microbiocides, contaminants,…
Opportunity
• Develop rxn-sepn methods or processes that convert these
to value-added products (flavors, perfumes, nutraceuticals,..)
Needs
• New enzymes, catalysts, and/or reaction-sepn processes
• Insight and new data on mechanisms & kinetic-transport effects
• Mathematical models for the kinetic-transport processes
Conclusions
• Citrus waste has potential as a biorefinery platform.
• Notable differences vs corn & grain-based processes.
• Conversion to EtOH represents one useful application.
• Specialty products would enhance economic potential.
• Various opportunities for novel enzymes, catalysts,
reactors, separations, & derivatives.