Food Biotechnology ( N.INDRA )
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FOOD BIOTECHNOLOGY
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FERMENTATION,
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BATCH AND CONTINUOUS FERMENTATION
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SOLID STATE FERMENTATION
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FERMENTOR DESIGN
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PRESENTED BY
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N.INDRA .
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FERMENTATION
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Fermentation is the oldest form of biotechnology, essentially consisting of transformation of the simple raw materials into value added amazing range of products by utilizing the growth of microorganism.
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The basic purpose of micro organisms to break down the organic compounds is to get energy for their metabolic process.
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Some fermented products
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BATCH FERMENTATION
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A batch fermentation is regarded as a closed system.
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The sterile nutrient culture medium in the bioreactor is inoculated with micro organisms.
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The incubation is carried out under optimal physiological conditions.
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It may be necessary to add acid or alkali to maintain pH and antifoam agents to minimize foam under optimal conditions for growth.
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Under optimal conditions for growth the following typical phases of growth, are observed in batch fermentation.
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PHASES
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Lag phase
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Acceleration phase
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Logarithmic (log) phase (exponential phase)
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Deceleration phase
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Stationary phase
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Death phase
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LAG PHASE
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Initial period of culturing after inoculation is referred to as lag phase.
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During the lag phase, the micro organisms adopt to the new environment avaliable nutrients, pH etc.,
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There is no increase in the cell number, although the cellular weight may slightly increase.
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PHASES GRAPH
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Acceleration phase
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It is a brief transient period during which cells start growing slowly.
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This phase connects the lag phase and log phase.
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Log phase
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The most active growth of micro organisms and multiplication occur during log phase.
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The cells undergo several doublings and the cell mass increase when the number of cell or biomass is plotted against time on a semi logarithmic graph, a straight line is obtained.
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Growth rate of microbes in log phase is dependent on substrate (nutrient supply)
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STATIONARY PHASE
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The substrate in the growth medium gets depleted and the metabolic and products that are formed inhibit the growth, the cells enter the stationary phase.
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The microbial growth may either slow down or completely stop.
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The biomass may remain almost constant during this phase
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Death phase
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The cells die at an exponential rate.
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In the commerical and industrial fermentation, the growth of the microbes is the end of the log phase or just before the death phase begins and the cells harvested.
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CONTINUOUS FERMENTATION
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It is an open system.
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It involves the removal of culture medium continuously and replacement of this with a fresh sterile medium in a bioreactor.
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Both addition and removal are done at the same rate so that the working volume remains constant.
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Homogenously mixed Bioreactors
In this type, the culture solution is homogenously mixed
The bioreactors are of two types
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Chemostat bioreactors
The concentration of any one of the substrate is adjusted to control the cell growth and maintain a steady state.
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Turbidostat bioreactors
In this case, turbidity measurement is used to monitor the biomass concentration.
The rate of addition of nutrient solution can be appropriately adjusted to maintain a constant cell growth.
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SOLID STATE FERMENTATION
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Most fermentation technologies using microbes employ a fairly dilute medium where the substrate to be fermented is diluted in water and then inoculated with desired microbes.
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Some fungai can grow in conditions without free water.
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In this case the moisture required by the fungus exists than absorbed or complex form in the solid matrix , often ranging between 10% and 80% processes which exploit the growth of fungai in this type of system are designated solid state fermentation.
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EXAMPLES FOR SOLID SUBSTRATE FERMENTATION
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FERMENTOR DESIGN
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WINE MAKING FERMENTOR
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FERMENTOR DESIGN
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A fermentor is a device in which the organisms are cultivated and motivated to form a desired product
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Closed vessel or containment designed to give a right environment for optimal growth and metabolic activity of the organism
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Fermenter: for microbes/ Bioreactor : for eukaryotic cells
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Size variable ranging from 20-250 million litres or more.
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Large scale production (10-100L to1000-million L capacity)
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Regular monitoring for physical, chemical biological parameters is done through controlled systems of the fermentor, because these parameters influnces the growth of the microbes.
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As per requirements and use of types of microorganisms there are different types of fermentors available.
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The most common among these is stirred tank fermentor where impellers used to stirr the medium.
Helps to meet requirements of:
pH
temperature
aeration
agitation
drain or overflow
control systems
sensors
cooling to achieve maximum microbial yield
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The increasing concentration of microbial cells will deplete the dissolved O2 concentration resulting in creation of anaerobic conditions.
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The microbial growth will simultaneous decline in product production.
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The forced aeration favours rapid growth of micro organisms.
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A pH fitted with fermentor regularly monitors the pH and maintains at optimum by adding acid or alkali.
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