UNIT 3

Question 1

• ________is one of the oldest biotechnological processes used by humans to preserve and enhance the nutritional value of food.

Answer 1

Fermentation

Question 2

• ______ occurs naturally and has been harnessed for thousands of years in
various forms, including in ______, _______, _______, __________.

Answer 2

Fermentation

bread-making
alcoholic beverage production
dairy fermentation,
preservation of fruits and vegetables

Question 3

Unlike other food preservation methods, _______ does not require heat or preservatives. It is powered by microorganisms that break down complex organic compounds, making them more digestible and sometimes improving their flavor.

Answer 3

fermentation

Question 4

What is fermentation?

It turns NADH and pyruvate produced in the _______ into NAD+ and
various small molecules depending on the type of fermentation.

Answer 4

glycolysis step

Question 5

The fermenting microorganisms mainly involve L.A.B. like _____, ______, ______, _______, and Pediococcus and yeasts and molds like Debaryomyces, Kluyveromyces, Saccharomyces, Geotrichium, Mucor, Penicillium, and Rhizopus species.

Answer 5

Enterococcus
Streptococcus
Leuconostoc
Lactobacillus

Question 6

What is the main principle of fermentation?

Answer 6

To derive energy from carbohydrates in the absence of oxygen

Question 7

______ is first partially oxidized to pyruvate by glycolysis.

Then pyruvate is converted to alcohol or acid along with regeneration of ______ which can take part in glycolysis to produce more ATP.

Answer 7

Glucose

NAD+

Question 9

Fermentation yields only about 5% of the energy obtained by ________.

Answer 9

aerobic
respiration

Question 10

• Fermentation is an 1.)_______ process that is used for the production of energy from the partial oxidation of 2.)_______ or other carbon sources.
• The oxidation of the substrate, which occurs through the Embden–Meyerhoff (EMP) or Entner–Doudoroff(ED) pathways results in the production of 3.) _____, _____, _____.

Answer 10

1. anaerobic biochemical
2. glucose
3. Pyruvate, ATP, and NAD (P) H.

Question 11

In the absence of external electron acceptors, the _______ undergoes
reduction with the regeneration of _____.

This step is essential for the fermentation process to progress and it leads to the production of products (ethanol and organic acids).

Answer 11

pyruvate

NAD+(P)

Question 12

• 1.)______ is the main product of fermentation, and it is generated by
2.)________ at the substrate level.

• NADH is then re-oxidized, reverting to 3.)_______ in the second phase of
fermentation that reduces pyruvate to the fermentation product, such as
ethanol and lactate.

Answer 12

1. ATP
2. phosphorylation
3. NAD+

Question 13

Homolactic fermentation is carried out by bacteria belonging to the genera _____, _____, _____, _____, and by some species of the
genus Lactobacillus

Answer 13

Lactococcus, Enterococcus, Streptococcus, and Pediococcus

Question 14

Glucose → Lactic acid

Answer 14

Lactic Acid Fermentation

Question 15

Heterolactic fermentation is carried out by bacteria of the genera ______, _____, _____, and by heterofermentative lactobacilli.

Answer 15

Leuconostoc, Oenococcus, and Weissella

Question 16

Glucose → Lactic acid + Acetic acid + Ethyl alcohol + 2CO2 + H2O

Answer 16

Lactic Acid Heterofermentation

Question 17

Propionic acid fermentation is carried out by several bacteria that belong to the genus ________ and the species __________.

Answer 17

Propionibacterium

Clostridium propionicum

Question 18

Glucose → Lactic acid + Propionic acid + Acetic acid + CO2 + H2O

Answer 18

Propionic Acid Bacteria

Question 19

During propionic acid fermentation, both ______ and ______ can be used as the initial substrate.

When sugar is available, these bacteria use the EMP pathway to produce pyruvate; the pyruvate is carboxylated to oxaloacetate and then reduced to propionate via malate, fumarate, and succinate.

Answer 19

sugar and lactate

Question 20

Butanediol fermentation is carried out by members of the genera _____, _____, _____, ______, and Serratia.

The reactions that lead to the production of 2,3-butanediol involve a double ________.

Answer 20

Enterobacter, Erwinia, Hafnia, Klebsiella

Question 21

Diacetyl
↑
Citric acid→ Pyruvic acid + Acetylmethylcarbon
↓
2,3-Butylene glycol

Answer 21

Diacetyl and 2,3-butylene glycol fermentation

Question 22

_______ It is carried out by yeasts and some other fungi and bacteria.
The first step of the alcoholic fermentation pathway involves pyruvate, which is formed by yeast via the EMP pathway, while it is obtained through the ED pathway in the case of Zymomonas (bacteria).

Answer 22

Alcoholic fermentation

Question 23

Glucose → Ethyl alcohol

Answer 23

Alcohol fermentation

Question 24

Butyric acid fermentation is characteristic of several obligate anaerobic bacteria that mainly
belong to the genus ________.

Answer 24

Clostridium

Question 25

Application of food fermentation

Answer 25

Beverages production
Condiments production
Staple food production
Organic solvent production
Pharmaceutic Industry
Processing of meat and fish

Question 26

Application of fermentation in medicine

Answer 26

Production of antibiotics
Production of insulin
Production growth hormone
Production of vaccines
Production of interferon

Question 27

Application in the food industry

Answer 27

1. Production of fermented foods as cheese, wine, beer, bread, as high value products
2. Food grade bio preservatives
3. Functional food
4. Production of single cell protein

Question 28

Limitation of fermentation

Answer 28

Low scale productivity
Possibilities of contamination
Natural variations over time
Undesirable end product
Undesirable microbes grow

Question 29

Types of fermentation

Answer 29

1. Lactic Acid Homofermentation
2. Lactic Acid Heterofermentation
3. Propionic Acid Fermentation
4. Diacetyl 2,3 - Butylene glycol Fermentation
5. Alcohol Fermentation
6. Butyric Acid Fermentation