The Fermentation of Monosaccharides to make Ethanol

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The Fermentation of Monosaccharides to make
Ethanol
Sandra Reynolds University Senior College
Dr Paul Grbin Wine Horticulture, University of
Adelaide
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The Fermentation of Monosaccharides to make
Ethanol

• This material has been developed as a part of
  the Australian School Innovation in Science,
  Technology and Mathematics Project funded by the
  Australian Government Department of Education,
  Science and Training as a part of the Boosting
  Innovation in Science, Technology and Mathematics
  Teaching (BISTMT) Programme.

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Fermentation of Monosaccharides

• To make Ethanol Subtopic 5.3
• ETHANOL IS DERIVED BY FERMENTATION OF GLUCOSE
  WHICH CAN BE DERIVED BY HYDROLYSIS OF COMPLEX
  CARBOHYDRATES.

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The origins of wine-making are lost in
history. The earliest known beers were
brewed 6000 years ago in a country called
Sumer on the plains between the Tigris and the
Euphrates which is now part of Southern Iraq.
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To pick grapes at the right pH is
important Too much makes the wine undrinkable To
o little gives a flat taste
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Crushing Seeds stems are removed Grape juice
is called must.
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• Sulphur dioxide has been used in winemaking for
  100s of years to control the growth of unwanted
  microorganisms.
• Sodium sulphite, sodium hydrogen sulphite and
  sodium metabisulphite are used.
• A wrong yeast strain can produce an aroma
  described as wet horse blankets, cow manure and
  plastic bandages!

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Skins are removed from the must for white
wine. The skins give the red colour to red
wine!
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• C6H12O6(aq) ? 2CH3CH2OH 2CO2FERMENTATION
  of monosaccharides using enzymes in yeast
• Conditions
• Anaerobic
• Yeast to provide enzymes
• Warmth, 20 to 30 deg. C
• pH less than 7
• Dilute aqueous

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Saccharomyces cerevisiae the yeast that
provides our bread, wine and beer.Magnification
X 13,800
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Skilled volumetric analysis determines the acid
content of wine.
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Fractional Distillation of Wine to Produce
Spirits

• Maturation gives rise to new flavour components
  by many chemical changes and by extraction from
  oak casks.

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Wine is Mostly Water Has Poor Keeping Qualities

• Fractional distillation of wine produces up to
  96 ethanol
• Spirits contain 52 95 ethanol and these are
  not attacked by microbes.
• 100 ethanol is called absolute alcohol an
  excellent preservative!

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Australian brandy is double distilled
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Cognac is triple distilled
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Brandy whisky are matured in oak casks. Colour
and flavour components are extracted
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Some 400 flavour components have been
identified in whisky.
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Copper rum pump and rum measures to dispense
the daily tot on the Royal Yacht Britannia until
1970 when the rum issue was discontinued.
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Her Majestys proof spirit
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Australian wine ready for drinking
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Beer Making

• Subtopic 5.3
• ETHANOL IS PRODUCED BY FERMENTATION OF GLUCOSE
  WHICH CAN BE DERIVED BY HYDROLYSIS OF COMPLEX
  CARBOHYDRATES.

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To Make Ethanol in Beer

• THE WORLDS OLDEST RECIPE!
• WATER, MALT, HOPS, YEAST
• Beer is made by SOAKING malted barley with water,
  boiling it with hops cooling it and then letting
  the whole lot ferment and mature.
• This process was used at least 6000 years ago in
  Iraq to make ale bread.

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Wine is usually made from fruits. These contain
simple sugars.Beer is made from grain barley
is best. Grains contain starch.

• Simple sugars are called MONOSACCHARIDES e.g.
• - Glucose (blood sugar, grape sugar)
• - Fructose, (fruit sugar)
• C6H12O6
• Double sugars are called DISACCHARIDES E.g.
• - Maltose
• - Sucrose
• - Lactose
• C12H22O11

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Complex sugars are called POLYSACCHARIDES e.g. -
Starch (C6H10O5)n
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Barley Contains Enzymes to Convert Starch into
Fermentable Sugars

• These are released when the grain is soaked in
  water allowed to germinate for several days at
  18oC.
• This is called BARLEY MALT
• The Sumerians baked this into barley bread.

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Ground barley malt is soaked in water.This
revives the barley enzymes which break
polysaccharides into disaccharide.

• This reaction is called hydrolysis
• (C6H10O5)n ? C12H22O11

H2O
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Boiling the Filtered Mixture Kill Germs
Deactivates Enzymes

• Boiling extracts bitter resin from the hops
  makes them soluble.
• Hops also act as a preservative

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Fermentation
Yeasts are added to the cooled wort

• HYDROLYSIS
• C12H22O11 H2O ? 2C6H12O6
• OVERALL HYDROLYSIS
• (C6H10O5)n nH2O ? nC6H12O6
• FERMENTATION
• C6H12O6 ? 2C2H5OH 2CO2

Note Fermentation is an anaerobic process.
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After maturing for several weeks at low several
for several weeks at low temperatures, the amber
liquid is filtered, ready for bottling or
kegging.
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Making distilled spiritsThe word comes from
the latin destillaremeaning to drip
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The Fate of Alcohol is Vinegar Acidic Wine
Vin Aigre F

• Acetobacter bacteria that can use O2 to
  metabolise alcohol extract energy from it.
• CH3CH2OH O2 ? CH3COOH H2O
• The ethanoic acid formed is a far more potent
  antimicrobial than ethanol .
• Vinegar came to be one of the most effective food
  preservatives of ancient and modern times.

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Word List

• CARBOHYDRATES
• SIMPLE SUGAR
• DOUBLE SUGAR
• COMPLEX SUGAR
• GLUCOSE
• FRUCTOSE
• SUCROSE
• MALTOSE
• STARCH

• POLYSACCHARIDE
• HYDROLYSIS
• DISACCHARIDE
• HYDROLYSIS
• MONOSACCHARIDE
• FERMENTATION
• ANAEROBIC
• ETHANOL
• AEROBIC
• ENZYMES
• ETHANOIC ACID