Presented by: Shalini Saini
Fermentation is the process in which the terminal electron
acceptors and donors are organic compounds.
It is the conversion of carbohydrate to alcohols
and carbon dioxides, or organic acids using yeast, bacteria
or combination of that under anaerobic condtions(absence
Implies that the action of microorganisms is desirable.
Complex compounds such as glucose is broken down by the
action of enzymes into simpler compounds without and in
presence of oxygen.
Fermentation result in the production of energy in the
form of two ATP molecules, and produces less energy than
aerobic process of cellular respiration.
C6H12O6 2CO2+ C2H5OH+2ATP
Difference b/w fermentation
Energy difference b/w
Fermentation and respiration
The chemistry of fermentation were first investigated
by Louis Pasteur in 1860
He called the process la vie sans air, or life without air
In 1897, Hans and Eduard Beuchner discovered that
fermentation could occur in a cell-free extract of yeast
This work led to the elucidation of the enzymes involved
MICROORGANISMS INVOLVED IN FERMENTATION OF
Saccharomyces uvarum but in some cases Saccharomyces
Cerevisiae lead to the fermentation of carbohydrates.
It is useful to classify worts carbohydrates as fermentable
or non-fermentable on the basis of wether they can be
metabolised by brewer s̓ yeast.
WORTS-The class of compound present in greater abun-
-dance is carbohydrates. There many less abundant compou-
-nds viz., nitrogenous, inorganic ions, vitamines, polyphenols,
hops compounds, lipids and oxygen.
Worts is raw materialfrom which beer is made by the
metabolic action of brewer̓s yeast.
The more important fermentable carbohydrates are;
maltose, maltotriose, glucose, sucrose and fructose.
Fructose and sucrose come directly from malt; glucose,
maltose, and malitriose are formed during the mashing oper-
-ations and may also added as component of liquid adjunct
PATHWAYS INVOLVED IN FERMNTATION
The EMP or glycolytic pathway is one of the more important
And primitive pathway for metabolizing carbohydrates. It
Occurs not only in a large in a large array of aerobic, anaerobic
, and facultative microorganisms but also in mammalian and
The EMP is the principle route by which carbohydrates are
utilized during brewery fermentation.
The 2ATP is required for phosphorylating glucose and
susequently 2ATPs are recovered between glyceraldehyde-3-
Phosphate are readily interconvertible this pathway can
produce a total 4ATPS from each glucose-with a net gain of
2ATPs-and is the main source of cellular energy during
Other carbohydrates, such as a galactose, maltose, and
Maltotriose enter this pathway after being converted to
Brewer s̓ yeast does not excrete pyruvate but decarboxyl-
-ates it to yield acetaldehyde which is then reduced to
Oxidation-reduction is thereby balanced the NADH
produced during the oxidation glyceraldehyde-3-phosphate to
1,3-diphosphoglyceric acid is utilized in the reduction of
acetaldehyde to ethanol;the NAD+ regenerated in this way is
available for further oxidation of glyceraldehyde-3-
phosphate. Consequently, CO2 and ethanol are the principle by-
Product of this metabolic pathway.