1. Institute of Technology of Cambodia
Food and chemical engineering department
Production of Fermented Foods
Subject: General Microbiology
Professor: Dr. HUL Seingheng
Group : I3-8
Students : Miss Prak Sophearot
Miss Rap Vannthang
Mr Ros Sovannmakara
Miss Sar Sandap
Mr Sok Pisith

2. Fermented Food
Fermented Foods are foods which processed through the activities of microorganisms but in which the weight of the microorganisms in the food is usually small.
Ex: Bread, Cheese, Fish sauce, coffee, Tea, Cocoa….

3. The benefits of Fermented foods are:
Preserving Foods in low cost manner
Improvement of organoleptic properties
Removing unwanted(harmful) properties in raw material.
Improvement of nutritive content of food.
Reducing the cooking time

4. Fermented foods are mainly influenced by :
Nature of the substrate
Microorganism involved in the fermentation
The length of the fermentation
The treatment of the food during processing.

5. Fermented Food from Wheat (Bread)
Basic ingredients are flour, water, salt, and yeasts.
Other components and additive are: sugar, milk, eggs, shortening(fat) emusifiers, anti-fungal agents, anti- oxidants, enzyme, flavoring, and enriching ingredients.

6. Flour is the chief ingredient of bread and is produced by milling of grains of wheat.
Yeast: used for baking are Saccharomyces Cerevisiae.
Sugar
Shortening (Fat): increased loaf size; a more tender crumb; enhanced slicing.
Emulsifiers (Surfactants)

7. Milk: to make the bread more nutritious, to help improve the crust color.
Salt
Water
Enzymes
Mold-inhibitors (antimycotics)
Enriching additives

8. Baking process: Pre-fermentation (sponge mixing) Dough mixing
Cutting and rounding
First (intermediate) proofing
Molding
Second proofing
Baking
Cooling, Slicing and wrapping

11. Role of Yeasts in Bread-making:
The principle role of Yeast is to create leavening.
Methods of leavening is the increase in the size of the dough induced by gases during bread-making.

12. Process of Leavening:
During bread making, yeasts ferment hexose sugars mainly into CO2 and other alcohols. CO2 in the gaseous state become bubbles in dough which causes the dough to rise or leaven.
The total time taken for the yeast to act upon the dough varies from 2-6h or longer.

13. Factors which effect the leavening action of yeasts:
The nature of the sugar available
Osmotic pressure
Effect of nitrogen and other nutrients
Effect of fungal inhibitors
Yeast concentration

14. Flavor development:
Difference of process of baking to cause the aroma of fermentation also different.
The flavor compound found in bread are organic acids, esters, alcohols, aldehydes and other carbonyl compounds.

15. Baking:
Bread is baked at a temperature of about oC for 17-23mn. Various events occur during baking process as below:
At about 45oC alpha-amylase yielding fermentable sugars.
Between 50 and 60oC the yeast is killed.

16. At about 65oC the beta-amylase is thermally inactivated.
At about 87oC the cereal alpha-amylase is inactivated.
Finally, the gluten is denatured and coagulates, stabilizing the shape and the size of the loaf.

17. Fermented Food from Milk
Cheese
Yoghurt

18. Cheeses
Cheese is a highly proteinaceous food made from the milk of some herbivores.
Cheese made from the milk of goat and sheep has a much stronger flavor than that made from cow’s milk.

19. Stages in the manufacture of Cheeses
Standardization of milk
Inoculation of pure cultures of lactic acid bacteria as starter cultures
Adding of rennet for coagulum formation
Shrinkage of the curd
Salting of curd and pressing into shape
Cheese ripening

21. Yoghurt
Yoghurt is a dairy product produced by bacterial fermentation of milk
In the manufacture of yoghurt, two kinds of lactic acid bacteria,
Lactococcus spp, (Lactococcus salivarius and thermophilus,)
Lactobacillus spp, (Lacto. acidophilus, bulgaricus and bifidus.)

22. The bacteria produce lactic acid causing pH to drop to about 4-5 from about 7.0
This drop in pH causes the milk to coagulate.
The lactic acid give yoghurt its sour taste and limits the growth of spoilage bacteria.

23. Conclusion
To sump up, after the presentation, we hope that you all gain more knowledge related to the production of Bread and Cheeses.

24. Thanks You For Your Attention!!!