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FERMENTATION OFCARBOHYDRATES

Presented by: Shalini SainiM.Sc-Ist-year 2nd semRoll no.-1810

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FermentationFermentation is the process in which the terminal electronacceptors and donors are organic compounds. It is the conversion of carbohydrate to alcoholsand carbon dioxides, or organic acids using yeast, bacteriaor combination of that under anaerobic condtions(absence of oxygen.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 thanaerobic process of cellular respiration.

C6H12O6 2CO2+ C2H5OH+2ATP

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Fermentation processDifference b/w fermentationAnd respiration:

Respiration:C6H12O6+O2 6CO2+CH2O

Fermentation:C6H12O6 2C2H5OH+2CO2

Energy difference b/wFermentation and respiration

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The chemistry of fermentation were first investigated by Louis Pasteur in 1860He called the process la vie sans air, or life without airIn 1897, Hans and Eduard Beuchner discovered that fermentation could occur in a cell-free extract of yeastThis work led to the elucidation of the enzymes involved

HISTORYHISTORY

MICROORGANISMS INVOLVED IN FERMENTATION OFCARBOHYDRATES

Saccharomyces uvarum but in some cases SaccharomycesCerevisiae lead to the fermentation of carbohydrates.

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It is useful to classify worts carbohydrates as fermentable or non-fermentable on the basis of wether they can be metabolised by brewer s 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 brewers 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(syrup).

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SUMMARY OF GLYCOLYSIS

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PATHWAYS INVOLVED IN FERMNTATIONOF CARBOHYDRATES

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 other muscle.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 alcoholic fermentations.

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The major pathway of glucose utilization

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Other carbohydrates, such as a galactose, maltose, and Maltotriose enter this pathway after being converted toglucose.Brewer s yeast does not excrete pyruvate but decarboxyl--ates it to yield acetaldehyde which is then reduced to ethanol.Oxidation-reduction is thereby balanced the NADH produced during the oxidation glyceraldehyde-3-phosphate to1,3-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.

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ALCOHOLIC FERMENTATION OF CARBOHYDRATES

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Glucose-6-phosphateATPADP

Glucose-6-phosphate

EMP

Xylulose-5-phosphateco2

G3PPi

ATPADP

Dihydroxyacetone phosphateAcetyle phosphate

PK

Acetaldehyde

Ethanol

NADH+H+

NAD+

NADH+H+

NAD+

NAD+

NADH+H+

EMP

2(ADP+Pi)

2ATP

Pyruvate CO2

Lactate

2NAD+

2NADH+H+

Glycerol

NADH+H+

NAD+

Pi

Pi

Acetyle-coA

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ALCOHOLIC FERMENTATION

EMP Acetaldehyde Ethanol

HOMOLACTIC FERMENTATION

EMP LACTATE

HETEROLACTIC FERMENTATION

Glucose G6P Xu5P G3P pyruvate+lactate

+Acetyle phosphate Acetaldehyde Ethanol

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Acetic acid fermentation

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Propionic acid fermentation

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Fates of Pyruvate

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