1. Fermented Foods
Foods that have been subjected to the action of micro-organisms or enzymes, in order to bring about a desirable change.
Numerous food products owe their production and characteristics to the fermentative activities of microorganisms.
Fermented foods originated many thousands of years ago when presumably micro-organism contaminated local foods.

2. Fermented Foods Micro-organisms cause changes in the foods which:
Help to preserve the food,
Extend shelf-life considerably over that of the raw materials from which they are made,
Improve aroma and flavour characteristics,
Increase its vitamin content or its digestibility compared to the raw materials.

3. Table 1 Benefits of fermentation
Raw
material
Fermented
food
Benefit
Preservation
Milk
(Most materials)
Yoghurt, cheese
Enhancement of safety
Vinegar
Beer
Wine
Salami
Gari, polviho azedo
Soy sauce
Acid production
Acid and alcohol production
Production of bacteriocins
Removal of toxic components
Fruit
Barley
Grapes
Meat
Cassava
Soybean
Enhancement of nutritional value
Bread
Kimchi, sauerkraut
Nata de coco
Bifidus milk, Yakult,
Acidophilus yoghurt
Improved digestibility
Retention of micronutrients
Increased fibre content
Synthesis of probiotic compounds
Wheat
Leafy veges.
Coconut
Milk
Improvement of flavour
Coffee beans
Grapes
Coffee
Wine

4. Lactic Acid Bacteria Major group of Fermentative organisms.
This group is comprised of 11 genera of gram-positive bacteria:
Carnobacterium, Oenococcus, Enterococcus, Pediococcus, Lactococcus, Streptococcus, Lactobacillus, Vagococcus, Lactosphaera, Weissells and Lecconostoc
Related to this group are genera such as Aerococcus, Microbacterium, and Propionbacterium.

5. Lactic Acid Bacteria
While this is a loosely defined group with no precise boundaries all members share the property of producing lactic acid from hexoses.
As fermenting organisms, they lack functional heme-linked electron transport systems or cytochromes, they do not have a functional Krebs cycle.
Energy is obtained by substrate-level phosphorylation while oxidising carbohydrates.

6. Lactic Acid Bacteria
The lactic acid bacteria can be divided into two groups based on the end products of glucose metabolism.
Those that produce lactic acid as the major or sole product of glucose fermentation are designated homofermentative.
Those that produce equal amounts of lactic acid, ethanol and CO2 are termed heterofermentative.
The homolactics are able to extract about twice as much energy from a given quantity of glucose as the heterolactics.

7. Fermentation – Definition
Fermentation is the metabolic process in which carbohydrates and related compounds are partially oxidised, with the release of energy, in the absence of any external electron acceptors.
The final electron acceptors are organic compounds produced directly from the breakdown of the carbohydrates.
With fermentation, incomplete breakdown of the parent compound occurs and only a small amount of energy is released during the process.
The products of fermentation consist of some organic compounds that are more reduced than others

8. Glycolysis and Fermentation
Glycolysis, also called the Embden-Meyerhof pathway, is the metabolic pathway used to, begin to, break down glucose. Used by:
most autotrophic and heterotrophic organisms,
aerobes and anaerobes.
The name glycolysis literally means splitting (lysis) of sugar (glyco-).
It does not require oxygen and can occur in its presence or absence.

9. Glycolysis ATP. Required at steps 1 and 3,. Released at steps 7 and 10
Glycolysis ATP Required at steps 1 and 3, Released at steps 7 and Each glucose yields 2, three carbon sugars. There is a net yield of 2 ATP per glucose.

10. Sugar Catabolism Aerobic Metabolism (Respiration) or
The metabolism of glucose, or another sugar by glycolysis is a process carried out by nearly all cells. The end result of glcolysis is pyruvic acid.
How pyruvic acid is subsequently catabolised depends on whether it is broken down by:
Aerobic Metabolism (Respiration) or
Anaerobic Metabolism (Fermentation)

11. Aerobic Metabolism Formation of Acetyl-CoA and the Krebs cycle
Energetically far more efficient than fermentation
In conjunction with the electron transport chain where oxygen is the terminal electron acceptor
Produces 34 ATP (plus 4 from glcolysis) from each molecule of glucose

12. Fermentation homolactic acid fermentation and alcoholic fermentation.
Process by which pyruvic acid is metabolised in the absence of oxygen
Result of the need to recycle the limited amount of NAD by passing the electrons off to other molecules
Two of the most important and commonly occurring pathways are:
homolactic acid fermentation and
alcoholic fermentation.

13. Homolactic Acid Fermentation
Does not capture energy in ATP from the metabolism of pyruvic acid, but removes electrons from reduced NAD so that it can continue to act as an electron acceptor.
Alcoholic fermentation is a similar process
Thus, they indirectly foster energy capture by keeping glycolysis going.
Fermenation can occur via many other pathways
Reduced
NAD
+ H+
Oxidised
NAD H
O O
H3C - C - C - OH
OH O
H3C - C - C - OH H
Pyruvic acid Lactic Acid