1. Fermentation

2. 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.

3. Fermented Foods Help to preserve the food,
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.

4. Table 1 History and origins of some fermented foods
Approximate year
of introduction
Region
Mushrooms
Soy sauce
Wine
Fermented milk
Cheese
Beer
Bread
Fermented Meats
Sourdough bread
Fish sauce
Pickled vegetables
Tea
4000 BC
3000 BC
2000 BC
1500 BC
1000 BC
200 BC
China
China, Korea, Japan
North Africa, Europe
Middle East
North Africa, China
Egypt, Europe
Europe
Southeast Asia, North Africa
China, Europe

5. Fermented Foods
The term “biological ennoblement” has been used to describe the nutritional benefits of fermented foods.
Fermented foods comprise about one-third of the world wide consumption of food and % (by weight) of individual diets.

6. Table 2 Worldwide production of some fermented foods
Quantity (t)
Beverage
Quantity (hl)
Cheese
Yoghurt
Mushrooms
Fish sauce
Dried stockfish
1000 million
350 million
15 million
3 million
1.5 million
Beer
Wine

7. Table 3 Individual consumption of some fermented foods: average per person per year
Annual
consumption
Food
Country
Beer (I)
Wine (I)
Yoghurt (I)
Kimchi (kg)
Tempeh (kg)
Soy sauce (I)
Cheese (kg)
Miso (kg)
Germany
Italy, Portugal
Argentina
Finland
Netherlands
Korea
Indonesia
Japan UK
130 90 70 40 25 22 18 10 7

8. Table 4 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

9. Nata de Coco A high fiber, zero fat Philippino dessert.
A chewy, translucent, jelly-like food product produced by the bacterial fermentation of coconut milk.
Commonly sweetened as a candy or dessert, and can accompany many things including pickles, drinks, ice cream, and fruit mixes.
Highly regarded for its high dietary fiber, and its zero fat and cholesterol content.
It is produced through a series of steps ranging from milk extraction, mixing, fermentation, separating, cleaning, cutting to packaging.

10. 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.

11. 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.

12. 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.

13. Lactic Acid Bacteria
All members of Pediococcus, Lactococcus, Streptococcus, Vagococcus, along with some lactobacilli are homofermenters.
Carnobacterium, Oenococcus, Enterococcus, Lactosphaera, Weissells and Lecconostoc and some Lactobacilli are heterofermenters
The heterolactics are more important than the homolactics in producing flavour and aroma components such as acetylaldehyde and diacetyl.

14. Lactic Acid Bacteria - Growth
The lactic acid bacteria are mesophiles:
they generally grow over a temperature range of about 10 to 40oC,
an optimum between 25 and 35oC.
Some can grow below 5 and as high as 45 oC.
Most can grow in the pH range from 4 to 8. Though some as low as 3.2 and as high as 9.6.

15. Starter Cultures
Traditionally the fermenting organisms came from the natural microflora or a portion of the previous fermentation.
In many cases the natural microflora is either inefficient, uncontrollable, and unpredictable, or is destroyed during preparation of the sample prior to fermentation (eg pasteurisation).
A starter culture can provide particular characteristics in a more controlled and predictable fermentation.

16. Starter Cultures
Lactic starters always include bacteria that convert sugars to lactic acid, usually:
Lactococcus lactis subsp. lactis,
Lactococcus lactis subsp. cremoris or
Lactococccus lactis subsp. lactis biovar diacetylactis.
Where flavour and aroma compounds such as diacetyl are desired the lactic acid starter will include heterofermentative organisms such as:
Leuconostoc citrovorum or
Leuconostoc dextranicum.

17. Starter Cultures flavour, aroma, and alcohol production
The primary function of lactic starters is the production of lactic acid from sugars
Other functions of starter cultures may include the following:
flavour, aroma, and alcohol production
proteolytic and lipolytic activities
inhibition of undesirable organisms

18. A good starter CULTURE will:
Convert most of the sugars to lactic acid
Increase the lactic acid concentration to 0.8 to 1.2 % (Titratable acidity)
Drop the pH to between 4.3 to 4.5

19. Food scientists frequently use the ability of bacterial cells to grow and form colonies on solid media to:
isolate bacteria from foods,
to determine what types and
how many bacteria are present.
Streak plates
A single bacterial colony

20. When conditions are right bacteria can double in number every 20 minutes

21. Microscopic examination
Can provide information on the size
and shape of the bacteria
Rods (1)
Cocci (2)
Spiral (3)
It cannot provide enough information
to enable bacteria to be identified