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Difference between revisions of "Industrial fermentation"
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Industrial fermentation (view source)
Revision as of 13:09, 30 November 2021
, 13:09, 30 November 2021wrote feedstock section
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== Feedstock == | == Feedstock == | ||
=== | === Lignocellulose and cellulose === | ||
Lignocellulose is present in [[garden and park waste]]. Cellulose is present in [[food waste]] such as fruit and vegetable waste. Via [[hydrolysis]], which is usually performed through enzymatic or thermal treatment, fermentable sugars can be obtained from lignocellulose and cellulose. | |||
=== Starch === | |||
Starch is present in [[food waste]] such as potatoes, corn, wheat or cassava. Starch can directly be utilized by amylase-producing microorganisms, particularly filamentous fungi. However, to allow its use in a wider range of fermentations, starch is usually converted into glucose or dextrins by enzymatic hydrolysis. | |||
=== Oils and Fat === | |||
Oils and fats are present in [[food waste]] such as gravy, used cooking oil and grease. The can directly be used as fermentation substrate. As they are not water soluble, extensive mixing is required to allow a good contact between the liquid droplets and the fermentation water phase. | |||
=== Dairy waste === | |||
Whey, the liquid by-product of cheese manufacturing, typically contains 4% lactose, 1% | |||
protein, 1% ash, and some lactic acid as shown in table 12. Whey is used as a source of | |||
fermentable carbohydrate and nitrogen. | |||
=== Pre-treatment === | === Pre-treatment === | ||
Depending on the type of feedstock, some pre-treatment technologies are required to provide fermentable substrates to the microorganisms. | |||
Most of the mentioned feedstocks provide the carbon source (which compose about 50% of the weight of most microorganisms), however, also other nutrients such as nitrogen, phosphate and potassium should be added. | |||
==Process and technologies== | ==Process and technologies== | ||
=== Microorganisms === | === Microorganisms === | ||
In practice, well-known, productive and harmless production organisms are used that, equipped with the new genetic information, will produce the desired products in high yield and efficiency. These are the so-called GRAS organisms (Generally Regarded As Safe) and belong to the genera Bacillus, Aspergillus, Penicillium, Saccharomyces, etc. A major advantage is that these genetically modified microorganisms do their work under controlled conditions in a fermenter or bio-reactor, carefully contained and separated from the outside world (contained environment). They cannot escape from the factory so that ecological problems or concerns regarding the release of genetically modified organisms in the environment are avoided. | In practice, well-known, productive and harmless production organisms are used that, equipped with the new genetic information, will produce the desired products in high yield and efficiency. These are the so-called GRAS organisms (Generally Regarded As Safe) and belong to the genera ''Bacillus, Aspergillus, Penicillium, Saccharomyces'', etc. A major advantage is that these genetically modified microorganisms do their work under controlled conditions in a fermenter or bio-reactor, carefully contained and separated from the outside world (contained environment). They cannot escape from the factory so that ecological problems or concerns regarding the release of genetically modified organisms in the environment are avoided. | ||
=== Equipment === | |||
A typical industrial fermenter consists of an CSTR equipped with: | |||
* an aeration and agitation system: to provide good mixing and availability of oxygen for the cell culture | |||
* a temperature and pH control system: to assure optimal conditions for growth or production | |||
* a foam control system: to avoid excessive foam formation | |||
* sampling ports | |||
* addition ports | |||
* a cleaning and sterilization system: to avoid contamination with other, undesired microorganisms | |||
Industrial production fermenters are mostly made of stainless steel, while labfermenters are made from glass. | |||
=== | === Operating mode === | ||
Industrial fermentations may be carried out | Industrial fermentations may be carried out as batch, fed-batch, or continuous culture systems. Batch and fed-batch operations are quite common, continuous fermentations being relatively rare <ref>{{Cite book|author=Y. Chisti|year=2014|book_title=Encyclopedia of Food Microbiology (Second Edition)|publisher=Science Direct}}</ref>. | ||
=== Scale-up of industrial fermentations === | === Scale-up of industrial fermentations === | ||
Typically, a pure starter culture (or seed), maintained under carefully controlled conditions, is used to inoculate sterile petri dishes or liquid medium in the shake flasks. After sufficient growth, the preculture is used to inoculate the seed fermenter. Because industrial fermentations tend to be large (typically 1–250 m<sup>3</sup>), the inoculum is built up through several successively larger stages, to 5–10% of the working volume of the production fermenter. However, scale-up of a fermentation process is not straightforward as an increase in fermenter size affects the various process parameters in different ways. Therefore, ample expertise is required to find a compromise between all process parameters. | Typically, a pure starter culture (or seed), maintained under carefully controlled conditions, is used to inoculate sterile petri dishes or liquid medium in the shake flasks. After sufficient growth, the preculture is used to inoculate the seed fermenter. Because industrial fermentations tend to be large (typically 1–250 m<sup>3</sup>), the inoculum is built up through several successively larger stages, to 5–10% of the working volume of the production fermenter. However, scale-up of a fermentation process is not straightforward as an increase in fermenter size affects the various process parameters in different ways. Therefore, ample expertise is required to find a compromise between all process parameters. | ||
==Products== | ==Products== | ||
=== Biomass === | === Biomass === | ||
Single cell protein (SCP) | Single cell protein (SCP) can be used as food or feed. | ||
=== Bio-products === | === Bio-products === | ||
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==== Biopolymers ==== | ==== Biopolymers ==== | ||
==== | ==== Biocolorants ==== | ||
==== Organic acids ==== | ==== Organic acids ==== | ||
'''Citric acid''' a | * '''Lactic acid''' had widespread applications in a range of industries: cleaning agents, personal care, food preservative, medical use, etc. It is also the precursor for polylactic acid (PLA), a biodegradable plastic. | ||
* '''Citric acid''' a food additive | |||
==== Alcohols ==== | |||
* Ethanol | |||
==== Vitamins ==== | ==== Vitamins ==== | ||
Vitamin-B12 | * Vitamin C | ||
* Vitamin-B12 | |||
==== Antibiotics ==== | ==== Antibiotics ==== | ||