Fermentation has many important uses in industry. Though the word fermentation can have stricter definitions, when speaking of it in industrial fermentation it more loosely refers to the breakdown of organic substances and re-assembly into other substances.
Somewhat ironically, fermenter culture in industrial capacity often refers to highly oxygenated and aerobic growth conditions, whereas fermentation in the biochemical context is a strictly anaerobic process
Ancient fermented food processes, such as making bread, wine, cheese and etc., can be dated to more than 6,000 years ago.
They were developed long before man had any knowledge of the existence of the microorganisms involved.
Fermentation is a powerful economic incentive for semi-industrialized countries, in their willingness to produce bio-ethanol.
Pharmaceuticals and the biotechnology industry
There are 5 major groups of commercially important fermentation:
Microbial cells or biomass as the product, e.g.: bakers yeast, lactobacillus, etc.
Growth factors: Some microorganisms cannot synthesize the required cell components themselves and need to be supplemented, e.g.: with thiamine, biotin, calcium pentothenate.
Nutrient sources for industrial fermentation
Precursors: Directly incorporated into the desired product: Phenyl ethylamine into Benzyl penicillin, Phenyl acetic acid into Penicillin G (for the making of Penicillin).
Inhibitors: To get the specific products: e.g.: sodium barbital for rifamycin.
Inducers: The majority of the enzymes used in industrial fermentation are inducible and are synthesized in response of inducers: e.g. starch for amylases, maltose for pollulanase, pectin for pectinase,olive oil and tween are also used at times.
Chelators: Chelators are the chemicals used to avoid the precipitation of metal ions. Chelators like EDTA, citric acid, polyphosphates are used in low concentrations.
EXAMPLE: Fermentation (wine)
The process of fermentation in wine is the catalyst function that turns grape juice into an alcoholic beverage.
During fermentation = yeast interact with sugars in the juice to create ethanol, commonly known as ethyl alcohol, and carbon dioxide (as a by-product).
In winemaking the temperature and speed of fermentation is an important consideration as well as the levels of oxygen present in the must at the start of the fermentation (aerobic fermentation).
The risk of immovable fermentation and the development of several wine faults can also occur during this stage which can last anywhere from 5 to 14 days for primary fermentation and potentially another 5 to 10 days for a secondary fermentation.
Fermentation may be done in stainless steel tanks, which is common with many white wines in an open wooden container, inside a wine barrel and inside the wine bottle itself like in the production of many sparkling wines
During fermentation there are several factors that winemakers take into consideration.
The most notable is that of the internal temperature of the medium.
The biochemical process of fermentation itself creates a lot of residual heat which can take the medium out of the ideal temperature range for the wine.
Typically white wine is fermented between 64-68 °F (18-20 °C) though a wine maker may choose to use a higher temperature to bring out some of the complexity of the wine.
Red wine is typically fermented at higher temperatures up to 85 °F (29 °C).
Fermentation at higher temperatures may have adverse effect on the wine in stunning the yeast to inactivity and even “boiling off” some of the flavors of the wines.
Some winemakers may ferment their red wines at cooler temperatures more typical of white wines in order to bring out more fruit flavors.
To control the heat generated during fermentation the winemaker has to choose a suitable vessel size or to use cooling devices of various sorts from the ancient Bordeaux traditions of placing the fermentation container on top of blocks of ice to today’s modern use of sophisticated fermentation tanks with built in cooling rings.
A risk factor involved with fermentation is the development of chemical residue and spoilage which can be corrected with the addition of sulfur dioxide (SO2), although excess SO2 can lead to a wine fault.
A winemaker who wishes to make a wine with high levels of residual sugar (like a dessert wine) may stop fermentation early either by dropping the temperature of the medium to stun the yeast or by adding a high level of alcohol (like brandy) to the medium to kill off the yeast and create a fortified wine.
Other types of fermentation
In winemaking there are different processes that fall under the title of “Fermentation” but might not follow the same procedure commonly associated with wine fermentation.
(1) Bottle fermentation:
Bottle fermentation is a method of sparkling wine production originating in the Champagne region where after the medium has gone through a primary yeast fermentation – the wine is then bottled and goes through a secondary fermentation where sugar and additional yeast is added to the wine.
This secondary fermentation is what creates the carbon dioxide bubbles that sparkling wine is known for.
The process of carbonic maceration is also known as whole grape fermentation where instead of yeast being added to grape, the medium fermentation is encouraged to take place inside the individual grape berries (enzymes inside the grapes).
This method is involving with whole clusters of grapes being stored in a closed container with the oxygen in the container being replaced with carbon dioxide.
Unlike normal fermentation where yeast converts sugar into alcohol, carbonic maceration works by enzymes within the grape by breaking down the cellular matter to form ethanol and other chemical properties.
The resulting wines are typically soft and fruity.
Other types of fermentation
(3) Malolactic fermentation:
Instead of yeast, bacteria plays a fundamental role in malolactic fermentation which is essentially the conversion of malic acid into lactic acid.
This has the benefit of reducing some of the bitterness (acidity) and making the resulting wine taste softer.
Depending on the style of wine that the winemaker is trying to produce, malolactic fermentation may take place at the same time as the yeast fermentation.
“Carbon dioxide is visible during the fermentation process in the form of bubbles in the fermented medium”