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Definitions
Biomass
Lignocellulosic biomass
the relatively large amounts of heterogeneous matterproduced by living organisms. It includes residues
originating from plants, animals, and microorganisms
Biomaterials whose composition is dominated by lignified cell walls from vegetative plants.
Polysaccharide and lignin content of representativelignocellulosic feedstocks a,b
Component Lignocellulosic Material
(Straw)
Glucan 31.9
Xylan 18.9
Arabinan 2.1
Mannan 0.2
Galactan 0.6
Lignin 22.8
Sum of above 76.5
a values are percentages on a dry weight basisb data taken from Puls and Schuseil (1992)c measured as Klason lignin
Biomass(cellulose, Hemicellulose, lignin)
Milled Biomass
Ethanol
Prehydrolysate Liquid(xylose, 2-furaldehyde)
Pretreated solid(cellulose, lignin)
Mechanical chipping/grinding
Pretreatment(Dilute acid, 180oC)
FermentationEnzymatic saccharification(fungal cellulases)
Hydrolyzed Solid(lignin)
Hydrolysate Liquid(glucose)
Ethanol
fermentation
Compositions Range Average
Starch 61.0 – 78.0 71.7
Protein 6.0 – 12.0 9.5
Fat 3.1 – 5.7 4.3
Ash 1.1 – 3.9 1.4
Cellulosea 3.3 – 4.3 3.3
Pentosansb 5.8 – 6.6 6.2
Sugarsc 1.0 – 3.0 2.
other 1.0
Chemical Composition of Corn
(percent of dry matter)
aplus ligninbas xylosecas glucose
Corn Wet MillingClean Corn
Steeps Steep water (6.5%)
Mill and Screen System
Germ System
Wash
Centrifugal Separator
Losses (1%)
Adapter from C.R. Keim, 1999
Germ (8%)
Fiber (10.2%)
Prime Starch (68%)
Gluten (6.3%)
Enzymatic Starch Conversion
Starch Slurry
Liquefaction Maltodextrin
Purification
Saccharification
Refining
Isomerization
Adapter from H.S. Olsen, 1995
To Fuel Ethanol
Maltose Syrups
Fructose Syrups
-amylase
Glucoamylase/Pullulanase
Glucose Syrups
Mixed Syrups
GlucoseIsomerase
Fate of Pyruvate
• Lactate dehydrogenase– during exercise– Reversible in liver– Location: cytoplasm
• Pyruvate dehydrogenase– Source of AcetylCoA– Irreversible reaction– Location: Mitochondria
• Ethanol synthesis– In yeast, some bacteria– Location cytoplasm
Reduction of pyruvate to ethanol (microorganism)
• It occurs by the 2 reactions shown below:
• The overall reaction of alcohol fermentation:
• Glc+2ADP +2P---------> 2 Ethanol + 2CO2 + 2ATP + 2 H2O
There is no net oxidation-reduction in the conversion of Glc into Ethanol, NAD+ is used first and made it later!
Pyruvate decarboxylase is present in brewer’s and baker’s yeast. CO2 produced during alcohol fermentation is responsible for the characteristic
carbonation of champagne.
In baking, CO2 fermentation by pyruvate decarboxylase during fermentation of dough due to CO2 , dough rises.
Alcohol dehydrogenase metabolizes alcohol.
TPP carries “active aldehyde” groups
The pyruvate decarboxylase reaction is the first reaction we see that TPP is involved. TPP------> Vit B1. If B1 is not enough
More about TPP• TPP plays an important role in the cleavage of bonds adjacent to a
carbonyl group such as the decarboxylation of alpha-ketoacids and in chemical rearrangements involving transfer of an activated aldehyde group from one C to another.
• The functional part of TPP is the thiazolium ring. The proton at C-2 of the ring is relatively acidic, loss of this proton, produces an active site in TPP.
• TPP is involved in the following reactions– 1. Pyruvate decarboxylase– 2. Pyruvate dehydrogenase– 3. Alpha-Ketoglutaratedehyrogenase– 4. Transketolase
Microbial fermentation yield other end products of commercial value:
Lactate and ethanol are the common products of microbial fermentation Clostridium acetobutyricum, ferments starch to butanol and acetone.
Here comes industrial fermentation, purpose is to make important products from readily available material (like starch) by using
microorganism.
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