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

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….

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

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.

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.

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)

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

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

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.

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.

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

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.

Baking: Bread is baked at a temperature of about 215-225oC 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.

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.

Fermented Food from Milk Cheese Yoghurt

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.

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

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.)

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.

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

Thanks You For Your Attention!!!