Transcript Fermentation How is fermentation used to make ethanol?

Fermentation
How is fermentation used to make ethanol?
Ethanol
Ethanol is an
important chemical
with a wide variety
of uses. More than
330000 tonnes of
pure ethanol are
produced in this
country each year.
The process of making ethanol
Ethanol is produced by fermentation.
Yeast is added to a sugar solution and
left for several days in the absence of
air. These anaerobic conditions
causes zymase enzymes in the yeast
to convert the glucose into ethanol
and carbon dioxide.
But there are also other new ways to
make ethanol now thanks to
technology.
New ways of making ethanol
There are now new ways of
making alcohol other than
fermentation.
One way is by reacting
ethene with steam, this is
called hydration.
•The reaction is reversible
which is shown by the
double arrow.
•Only 5% of the ethene is
converted into ethanol.
•But this isn’t a problem
as the ethanol can be
removed and the ethene
left over can be recycled,
by doing this over 95%
can be converted.
New ways of making ethanol
Genetically engineered E. coli
bacteria could produce fuel ethanol
from farm wastes such as corn stems,
cobs, and leaves. A related
technology can produce
biodegradable plastics from biomass.
This is done by genetically modifying
the bacteria to produce ethanol from
a waste biomass such as sugar cane,
corn husks, wood and other organic
matter.
The biomass is mixed with the
bacteria at 30-37°C and in slightly
acidic conditions (ph 6.6). The
ethanol produced is about 5% pure
and can then be concentrated by
fractional distillation.
Wine Making
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During the primary fermentation of wine,
the two grape sugars, glucose and fructose
are converted to alcohol (ethanol) by the
action yeast.
The by-products of primary fermentation
are aromas and flavours, the gas carbon
dioxide, and heat.
The production of heat during
fermentation means that during
fermentation the temperature of the
fermentation vessel will rise, and will
require action on the part of the
winemaker to cool it down.
White fermentation is usually conducted
in the range of 8-19°C, and red wine
fermentations typically are allowed to run
at between 25°C and 32°C. At
temperatures higher than this, there can
be a loss of desirable aroma and flavour.
•Saccharomyces cerevisiae and
Saccharomyces bayanus are the
bacteria that are responsible for
fermentation.
Websites
• http://www.chemguide.co.uk/organicprops/alkenes/hydratio
n.html
• http://www.isa.org/Template.cfm?Section=Departments4&te
mplate=/ContentManagement/ContentDisplay.cfm&ContentI
D=45357
• http://www.topnews.in/health/files/redWine.jpg