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FE308- Fermentation Technology
Spring 2016
Lecture 1
Basic Principles of Food Fermentations
Lecturer:Dr. Çisem Bulut Albayrak
Basic Principles of Food Fermentation
• Introduction
• Fermentation and Fermenting Microorganisms
A)Food Fermentation
B)Fermented Foods: An ancient Tradition
C)Factors Influencing Fermentation
D)Biological Agents Responsible in Food
Fermentation
“fermentation, far from being a lifeless phenomenon,
is a living process…”
- Louis Pasteur
The Chemistry of Fermentation
- Aerobic & Anaerobic Cellular Respiration
- Glycolysis
- Alcoholic Fermentation
- Lactic Acid Fermentation
Aerobic Cellular Respiration
• Aerobic means “with air”. This type of respiration
needs oxygen for it to occur so it is called aerobic
respiration.
Glucose + Oxygen -> Carbon dioxide + Water + Energy
• The chemical equation is:
C6H12O6 + 6O2
-> 6CO2 + 6H2O + 2900 kj
• 3 stages: -glycolysis
-citric acid cycle
-electron transport chain
Stages of Aerobic Cellular Respiration
• In glycolysis, a net of 2 molecules of ATP, or
chemical energy, are produced.
• The citric acid cycle produces another
2 molecules of ATP
• The electron transport chain produces 28
molecules of ATP.
• Oxygen is used in aerobic cellular respiration as
the final electron acceptor in the electron
transport chain, which is part of why it's able to
create so much ATP.
But what happens when
oxygen doesn't exist?
Anaerobic Cellular Respiration
• In anaerobic cellular respiration, the only step of
this process that occurs is glycolysis.
What is fermentation?
• Derived from the Latin verb ‘fervere’ meaning
‘to boil’
What is fermentation?
• It is a process by which the living cell is able to
obtain energy through the breakdown of
glucose and other simple sugar molecules
without requiring oxygen.
• Fermentation results in the
production of energy in the
form of two ATP molecules,
and produces less energy than
the aerobic process of
cellular respiration .
• Louis Pasteur in the 19th century used the term
fermentation in a narrow sense to describe the
changes brought about by yeasts and other
microorganisms growing in the absence of air
(anaerobically);
• he also recognized
that ethyl alcohol and
carbon dioxide are
not the only products
of fermentation.
Definition
• Fermentation is the metabolic process in
which carbohydrates and related compounds
are oxidized with release of energy in the
absence of external electron acceptors under
anaerobic conditions.
Microbial cell (Biomass)
Yeast
Microbial enzymes
Glucose isomerase
Microbial metabolites
Penicillin
Food products
Cheese, yoghurt, vinegar
Vitamins
B12, riboflavin
Products of Fermentation
Fermentation products include:
• Food products: from milk (yogurt, kefir, fresh and
ripened cheeses), fruits (wine, vinegar), vegetables
(pickles, sauerkraut, soy sauce), meat (fermented
sausages, salami)
• Industrial chemicals: (solvents: acetone, butanol,
ethanol, enzymes, amino acids)
• Specialty chemicals (vitamins, pharmaceuticals)
Products of Fermentation
Most commercially useful
fermentations may be classified as
Solid state fermentation
Submerged fermentation
surface (solid state)
• microorganisms
cultivated on the surface
of a liquid or solid
substrate.
• complicated and rarely
used in industry.
• Mushroom,
cocoa, tempeh
bread,
submersion techniques.
microorganisms grow in a
liquid medium.
(biomass, protein,
antibiotics, enzymes and
sewage treatment) are
carried out by submersion
processes.
Some important fermentation products
Product
Ethanol
Glycerol
Lactic acid
Acetone and
butanol
-amylase
Organism
Saccharomyces
cerevisiae
Saccharomyces
cerevisiae
Lactobacillus
bulgaricus
Clostridium
acetobutylicum
Bacillus subtilis
Use
Industrial solvents,
beverages
Production of
explosives
Food and
pharmaceutical
Solvents
Starch hydrolysis
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Fermentor is the basic
equipment used for
fermentation.
contains the media to
carry out fermentation,
and creates environment
for fermentation at large
scale.
 Pure culture:
organism, quantity, physiological state
 Sterilised medium: for microorganism growth
 Seed fermenter:
inoculum to initiate process
 Production fermenter:
 Equipment
ii) cell separation
large model
i) drawing the culture medium
iii) collection of cell
iv) product purification v) effluent treatment.
II. Fermentation and Fermenting
Microorganisms
A)Food Fermentation
The food is metabolized as a result of anaerobic
fermentation which produces a mixture of
organic wastes including organic acids (e.g.
Formic acid, propionic acid, acetic acid and lactic
acids).Intrinsic and extrinsic factors are critical to
fermentation process.
Table 2.1 Major types of fermentation
via pyruvate as a key compound
1.
2.
3.
4.
Lactic acid homofermentation
Lactic acid heterofermentation
Propionic acid fermentation
Diacetyl and 2,3-Butylene glycol
fermentation
5. Alcoholic fermentation
6. Butyric acid fermentation
Lactic acid homofermentation
C6H12O6 2CH3CHOHCOOH
Glucose Lactic acid
Lactic Acid Heterofermentation
C6H12O6 + H2O
Glucose
2CH3CHOHCOOH+CH3COOH+C2H5OH+2CO2 +2H2
Lactic acid
Acetic acid Ethanol
Propionic Acid Fermentation
C6H12O6
2CH3CHOHCOOH
Glucose
Lactic acid
2CH3CH2COOH+CH3COOH
Propionic acid Acetic acid
Diacetyl and 2,3 Butylene Glycol
Fermentation
CH3COCOCH3
Diacetyl
CH2COOHHOCOOH 2CH3COCOOH CH3COCHOHCH3+2CO2
Citric acid
Pyruvic acid
Acetylmethycarbinol
CH3CHOHCHOHCH3
2,3 Butylene glycol
Alcoholic Fermentation
C6H12O6
Glucose
2CH2H5OH +2CO2
Ethyl alcohol
Butyric Acid Fermentation
C6H12O6
Lactic acid
CH3COOH+ CH3CH2CH2COOH
Acetic acid Butyric acid
Fermented Foods:An ancient Tradition
Human beings are known to have made fermented foods since
Neolithic times. The earliest types were beer, wine, and leavened
bread (made primarily by yeasts) and cheeses (made by bacteria and
molds). These were soon followed by East Asian fermented foods,
yogurt and other fermented milk products, pickles, sauerkraut, vinegar
(soured wine), butter, and a host of traditional alcoholic beverages.
More recently molds have been used in industrial fermentation to
make vitamins B-2 (riboflavin) and B-12, textured protein products
(from Fusarium and Rhizopus in Europe) antibiotics (such as penicillin),
citric acid, and gluconic acid. Bacteria are now used to make the amino
acids lysine and glutamic acid. Single-celled protein foods such as
nutritional yeast and microalgae (spirulina, chlorella) are also made in
modern industrial fermentations.
Fermentation is relatively efficient, low energy
preservation process which increases the shelf
life and decreases the need for refrigeration or
other form of food preservation.
Factors Influencing Fermentation
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Temperature
pH
Nature and composition of medium
Dissolved oxygen
Dissolved carbon dioxide
Operation system(batch,fed-batch,continuous)
Feeding with precursors
Mixing and shear rates in fermenter
Factors influencing fermentation may affect;
The rate of fermentation
The product spectrum and yield
The organoleptic properties of the
product(appearance, taste, smell and texture)
The generation of toxins
Nutritional quality
Other physicochemical properties
Medium Formulation
The formulation of fermentation medium affects
The yield rate and product profile. The medium must
provide the necessary amount of carbon,nitrogen ,trace
elements and micronutrients(e.g. Vitamins for
microorganisms)
Specific types of carbon and nitrogen sources may be
required
And carbon:nitrogen ratio may have to be controlled.
Some trace elements may have to be avoided, for
example minute amounts of iron reduce yields in citric
acid production by A. niger.
Fermentation medium
• Define medium ; nutritional, hormonal, and
substratum requirement of cells
• In most cases, the medium is independent of the
bioreactor design and process parameters
• The type: complex and synthetic medium (mineral
medium)
• Even small modifications in the medium could
change cell line stability, product quality, yield,
operational parameters, and downstream processing.
Medium composition
Fermentation medium consists of:
• Macronutrients (C, H, N, S, P, Mg sources water,
sugars, lipid, amino acids, salt minerals)
• Micronutrients (trace elements/ metals, vitamins)
• Additional factors: growth factors, attachment
proteins, transport proteins, etc)
For aerobic culture, oxygen is sparged
End