Microbial production of ethanol and acetic acid involves fermentation processes. Ethanol is produced by fermenting sugars from various sources like molasses, corn, or cassava using yeasts like Saccharomyces cerevisiae. The fermentation converts sugars into ethanol and carbon dioxide. Ethanol is recovered from the fermented product using distillation. Vinegar is produced through a two-stage fermentation where yeast first produce ethanol from sugars which is then oxidized to acetic acid by Acetobacter bacteria, yielding vinegar. Different types of vinegar are produced depending on the original substrate like wine, apple cider, rice, or malt.
2. PRODUCTION OF ETHANOL:
Microbial production of one of the organic feed stocks from
plant substances such as molasses is presently used for
ethanol production.
In modem era, attention has been paid to the production of
ethanol for chemical and fuel purposes by microbial
fermentation.
Ethanol is now-a-days produced by using sugar beet, potatoes,
com, cassava, and sugar cane.
3. What is Alcoholic Fermentation?
Alcoholic fermentation, also referred to as, Ethanol
fermentation, is a biological process in which sugars such as
glucose, fructose, and sucrose are converted into cellular
energy and thereby produce ethanol and carbon dioxide as
metabolic waste products.
The commercial production is carried out with Saccharomyces
cerevisiae.
Because yeasts perform this conversion in the absence of
oxygen ethanol fermentation is classified as anaerobic.
4.
5. The Candida utilis is used for the fermentation of waste
sulphite liquor since it also ferments pentoses.
It is noteworthy that the ethanol at high concentration
inhibits the yeast. Hence, the concentration of ethanol
reduces the yeast growth rate which affect the
biosynthesis of ethanol.
It can produce about 10-12 % ethanol but the demerit of
yeast is that it has limitation of converting whole biomass
derived by their ability to convert xylulose into ethanol.
11. FERMENTATION MEDIA:
Nutrient Raw material
Carbon Molasses, Starch
Nitrogen Corn steep liquor, Soybean meal, pure
ammonia or ammonium salts, Urea, nitrate
salts, phosphate salts
Vitamins Biotin, yeast extract, beef and growth extract,
corn steep liquor, factors wheat germmeal
12. CONDITIONS FOR FERMENTATION
Carbon sources: Pure sugar or crude sugars/molasses
(10-18%).
Nitrogen sources: Mostly available in the form of
ammonium sulphate.
Growth factors: can be provided in the form of molasses.
pH: 4.8-5.0.
Temperature: 70-80 F. Temp. can be controlled by cooling
jacket.
Time: Depends on yeast strain. Usual time is between 30 to
72hrs.
13.
14. 1. Preparation of Medium:
Three types of substrates are used
for ethanol production:
(a) Starch containing substrate,
(b) Juice from sugarcane or
molasses or sugar beet,
(c) Waste products from wood or
processed wood. Production of
ethanol from whey is not viable.
15. If yeast strains are to be used, the starch must be
hydrolyzed as yeast does not contain amylases. After
hydrolysis, it is supplemented with celluloses of microbial
origin so as to obtain reducing sugars.
On the other hand, if molasses are used for ethanol
production, the bagasse can also give ethanol after
fermentation.
Sulphite waste-liquor, a waste left after production of paper,
also contains hexose as well as pentose sugar. The former
can be microbially easily converted.
16. 2. Fermentation:
Ethanol is produced by continuous fermentation. Hence,
large fermenters are used for continuous manufacturing of
ethanol.
The process varies from one country to another.
India, Brazil, Germany, Denmark have their own technology
for ethanol production.
The fermentation conditions are almost similar (pH 5,
temperature 35°C) but the cultures and culture conditions
are different.
17. The fermentation is normally carried out for several days but
within 12h starts production.
After the fermentation is over, the cells are separated to get
biomass of yeast cells which are used as single cell protein
(SCP) for animal’s feed.
The culture medium or supernatant is processed for recovery
of ethanol.
18. Ethanol is also produced by batch fermentation as no
significant difference is found both in batch and
continuous fermentation.
Although as stated earlier within 12h Saccharomyces
cerevisiae starts producing ethanol at the rate of 10%
(v/v) with 10-20g cells dry weight/lit.
The reduction in fermentation time is accomplished use
of ceil recycling continuously in fermentation.
19. 3. Recovery:
Ethanol can be recovered upto 95 % by successive
distillations. To obtain 100 %, it requires to form an
azeotropic mixture containing 5 % water.
Thus 5 % water is removed from azeotropic mixture of
ethanol, water and benzene after distillation.
In this procedure, benzene water ethanol and then ethanol-
benzene azeotropic mixture are removed so that absolute
alcohol is obtained.
20.
21. Fermentation of biomass is a process where microbes use sugars as
food and simultaneously produce alcohols as a product of their
metabolism.
Cellulose containing biomass, like wood and straw, can be utilized
after acid or enzyme pre-treatment.
In the fermentation process, microbes (fungi, yeast or bacteria) split
organic matter, producing alcohols (usually ethanol) as a final
product.
First-generation biofuels made from agricultural crops are produced
commercially on a large scale and the industry is growing throughout
the world.
22. Second-generation biofuels made from wood and by-products (i.e.
ligno-cellulosic material) are more promising in the long term since
they do not use material suitable for food.
Various companies and research groups work intensively to
produce second-generation biofuels commercially.
The alcohol production process consists mainly of pre-treatment or
hydrolysis, fermentation, separation and purification.
Milling and, when using ligno-cellulosic feedstock, acid or enzyme
pre-treatment is the first step of the process. The sugars
produced are then fermented and solid residues are separated.
23. Ethanol is toxic to fermenting organisms at concentrations above
15 %, so that ethanol is continuously siphoned off at about 6 %
and purified to fuel-grade (over 99 %).
Distillation is a conventional and widely used method for the
purification of the fermented product to a fuel-grade ethanol, but
it is not effective regarding energy and economy.
Therefore, cheaper low-energy separation techniques are being
developed, including precipitation, chemicals-based techniques,
membrane separation and
24. BEER PRODUCTION:
Beer is the most consumed alcoholic beverage in the world. It is
made most often of malted barley and malted wheat.
Unmalted maize can be added to the barley or wheat to lower
cost.
Potatoes, millet and other foods high in starch are used in
different places in the world as the primary carbohydrate
source.
The process of making beer is called brewing.
It includes breaking the starch in the grains into a sugary liquid,
called wort, and fermenting the sugars in the wort into alcohol
and carbon dioxide by yeasts.
25. Two main species are used in the fermentation process:
Saccharomyces cerevisiae (top-fermenting, since it forms foam
on top of the wort) and
Saccharomyces uvarum (bottom-fermenting).
Top-fermenting yeasts are used to produce ale, while bottom-
fermenting produce lagers.
The temperature used for top-fermenting (15-24ºC) leads to
the production of a lot of esters and flavor products that give
beer a fruity taste.
Hops are added to introduce a bitter taste and to serve as a
preservative.
26. Brewer’s yeasts are very rich in essential minerals & B
vitamins, except of vitamin B12.
Other types of alcohol beverages are made by the fermentation
activity of microorganisms as well.
A few examples are sake (uses the fungus Aspergillus oryzae to
facilitate starch fermentation from rice), brandy, whiskey (both
are distilled alcohol), and other alcohol beverages with higher
percentage of alcohol compared to wine and beer.
27. STEPS IN BEER BREWING
1. Malting: Here the conversion from carbohydrates to dextrin
and maltose takes place. The grain used as the raw material is
usually barley.
Barley as a cereal can be preserved for a long time after
harvesting and it is the malted barley that gives Beer its
characteristic color and taste.
2. Milling: The malt is then mixed with water to complete the
conversion of starches in the grain to sugar. After that the
grain is milled to create the proper consistency to the malt.
28. 3. Mashing: This process converts the starches released during
the malting stage, into sugars that can be fermented.
4. Lautering: The liquid containing the sugar extracted during
mashing is now separated from the grains. It is then generally
termed as wort.
5. Boiling and Hopping: Boiling the wort, ensures its sterility,
and thus prevents a lot of infections. Hops are added during this
stage of boiling. Hops are used to add flavor and aroma to
balance the sweetness of the malt.
6. Fermenting: The yeast is now added and the Beer is
fermented. The yeast breaks down the sugars extracted from
the malt to form alcohol and CO2.
29. 7. Conditioning: Fermented Beer contains suspended particles,
lacks sufficient carbonation, lacks taste and aroma, and less
stable. Conditioning reduces the levels of these undesirable
compounds to produce a more finished product.
8. Filtering: Filtration helps to remove excess of the yeast and
any solids, like hops or grain particles, remaining in the Beer.
Filtering is the process which produces the clear, bright and
stable Beer.
9. Packaging: Packaging is putting the beer into the bottles,
cans or some other high volume vessels. One of the most
important things in packaging is to exclude oxygen away from
the Beer.
32. WINE PRODUCTION:
Wine is made from grapes or other fruit. The grapes are first
cleaned of leaves and stems and the fruit is crushed into must
that is ready for fermentation.
There are hundreds of commercially available yeast strains for
wine fermentation.
In the fermentation process, energy that is converted to heat is
produced as well. It is important to keep the temperature in the
fermentation vessel lower than 40ºC to keep the yeasts alive.
33.
34. To improve yeast growth, additional nutrients, like di-
ammonium phosphate, are sometimes added in the fermentation
step.
When making red wine, there is an additional fermentation step
after alcoholic fermentation.
Malic acid, naturally present in grape juice, can be converted to
lactic acid by lactic acid bacteria naturally found in wineries or
added artificially.
35. Product Recovery:
Distillation is a separation process for a mixture of liquids or oils.
It relies on differences in the boiling points of the component
liquids to be separated.
Alcohol can be obtained by distillation and column is known as
rectified column.
Can also be recovered by fractional distillation. Distillate
contains 95.6% ethyl alcohol and 4.4% water.
36. USES OF ETHANOL:
Some alcohols, mainly ethanol and methanol can be used as an
alcohol fuel.
Can be used as Preservative and Solvents
Alcohols have applications in industry and science as reagents
or solvents ethanol can be used as a solvent in medical drugs,
perfumes and vegetable essences such as vanilla.
Alcoholic beverages
Antifreeze
Ethanol can be used as an antiseptic to disinfect the skin
37. PRODUCTION OF VINEGAR:
Vinegar is the product of a two-stage fermentation. In the first
stage, yeast convert sugars into ethanol anaerobically, while in
the second ethanol is oxidized to acetic (ethanoic) acid
aerobically by bacteria of the genera Acetobacter and
Gluconobacter.
This second process is a common mechanism of spoilage in
alcoholic beverages and the discovery of vinegar was doubtless
due to the observation that this product of spoilage could be put
to some good use as a flavoring and preservative.
38. The name vinegar is in fact derived from the French vin aigre for
‘sour wine’ and even today the most popular types of vinegar in a
region usually reflect the local alcoholic beverage;
For example, malt vinegar in the UK, wine vinegar in France, and
rice vinegar in Japan.
In vinegar brewing, the alcoholic substrate, known as vinegar stock,
is produced using the same or very similar processes to those used
in alcoholic beverage production.
39. Acetification, the oxidation of ethanol to acetic acid is performed
by members of the genera Acetobacter and Gluconobacter.
These are Gram-negative, catalase-positive, oxidase-negative,
strictly aerobic bacteria.
Acetobacter spp. are the better acid producers and are more
common in commercial vinegar production because they have the
ability to convert ethyl alcohol, into acetic acid, by oxidation.
40.
41. Different Types Of Vinegar:
White Vinegar: It is made either from
grain-based ethanol or laboratory-produced
acetic acid & then diluted with water.
Apple Cider Vinegar: Second-most-common
type of vinegar. This helps in controlling
diabetes, blood sugar level , aids to weight
loss, stops itch caused by bugs & insects,
clears sunburns and pimples, eases sore
throat and indigestion.
Wine Vinegar: Flavorful type of vinegar is
made from a blend of either red wines or
white wines.
42. Balsamic Vinegar: Prepared from Trebbiano
Grapes.
Rice Vinegar: made from the sugars found in
rice, and the aged, filtered final product has a mild,
clean, and delicate flavor sometimes with the
addition of sugar. Rice vinegar also comes in red
and black varieties.
Malt vinegar: Production begins with the
germination, or sprouting, of barley kernels.
Germination enables enzymes to break down starch.
Cane Vinegar: Produced from sugar cane juice.
Beer Vinegar: Produced from beer & its flavor
depends on the brew.
43. Coconut Vinegar: Prepared from coconut
water.
Raisin Vinegar: This slightly cloudy brown
vinegar traditionally prepared in Turkey.
Date Vinegar: Prepared from Dates.
Distilled Vinegar: Prepared by fermentation
of distilled alcohol.
Honey Vinegar: Prepared from Honey.
44. Flavoring Agents:
Herbs and fruits are used to flavour vinegar.
Commonly used herbs include tarragon, garlic and basil.
Popular fruits are raspberries, cherries and lemons.
45. 1. The Orleans Method
This is one of the older and slower methods of creating a high-
quality vinegar.
This method involves the fermenting of vinegar inside a cask that
has holes drilled into it to allow oxygen inside. These holes also
have screen filters that prevent insects and bugs from entering
the cask which will disturb the production.
Oxygen is necessary for the production of vinegar due to the fact
that the bacteria that turns the solution into vinegar requires
oxygen.
46. To create the vinegar, alcoholic liquid is poured into the cask and
then about 20% of fresh vinegar is poured into the cask to begin
the fermentation process.
Once the Acetobacter bacteria oxidizes the acetic acid the
vinegar is now finished.
There is a plug on the cask to collect the finished vinegar, and
also a tube to add more substances without destroying the film
of vinegar bacteria.
47.
48. 2. The Trickling, Quick Process
Since the Orleans method is very slow, many have tried to
increase production rate with newer methods.
This method of producing vinegar involves spraying the
alcoholic substrate in the top layer of the fermentation
chamber where it is filled with materials that carry a slime
made of acetic bacteria so that the bacteria could react with
the substrate and create vinegar.
Due to the heat that is made during the fermentation of
vinegar, air is forced through the chamber to keep it cool.
49. The vinegar is re-
circulated two-three
times until the desired
concentration of
vinegar is achieved.
Once the vinegar is
achieved it is then
collected from the
collection chamber.
50. 3. The Submerged Fermentation Method
This method is the newer, faster, and more efficient methods of
creating vinegar.
It is mainly used in industrial businesses where the needed
equipment is present.
In this method A high speed motor breaks down air that is brought
down from a stainless steel tank into tiny bubbles and is forced
into the solution of alcoholic liquid and the bacteria for even
faster oxidization.
51. The final steps are filtration and pasteurization of the
vinegar to stop any more bacteria growth and enzyme
actions.
This process usually take one to two days to process
which is why this method is mainly used by big industries.
52.
53.
54. Quality Control:
The growing of acetobacters, the bacteria that creates vinegar,
requires vigilance.
In the Orleans Method, holes must be checked routinely to
ensure that insects have not penetrated the netting.
Workers routinely check the thermostats on the container.
Because a loss of electricity could kill the acetobacters within
seconds, many vinegar plants have backup systems to produce
electrical power in the event of a blackout.
55. Byproducts/Waste:
Vinegar production results in very little by-products or
waste.
In fact, the alcohol product is often the by-product of
other processes such as winemaking and baker’s yeast.
Some sediment will result from the submerged
fermentation method. This sediment is biodegradable
and can be flushed down a drain for disposal.
56. Benefits Of Vinegar:
It reduces bloating
It increases the benefits of the vitamins and minerals in your
food.
It cancels out some of the carbs you eat
It softens your energy crash after eating lots of sugar or
carbs.
It can help your muscles produce energy more efficiently
before a major push.
57. It could lower your blood pressure.
It cleans fruits and veggies
It kills bad breath and deodorizes smelly feet.
It balances your body's pH levels, which could mean
better bone health.
It alleviates heartburn — sometimes
58. Drawbacks:
It may cause your potassium levels to drop too low.
It might also affect medications that treats diabetes and
heart disease
And of course, its strong taste might not be for everyone.
