1. BIOLOGY 2250 MICROBIAL GROWTH and ITS CONTROL

2. BIOLOGY 2250 PART 1. MICROBIAL GROWTH

3. Requirements for Growth Physical Requirements – Temperature, pH, Osmotic Pressure Chemical Requirements – Carbon, Nitrogen, Sulfur, Phosphorous, Trace Elements, Oxygen, Organic Growth Factors

4. Temperature Requirements Mesophiles Psychrophiles Psychotrophs Thermophiles Hyperthermophiles

5. TEMPERATURE OF FOODS

6. OSMOTIC PRESSURE

7. OXYGEN REQUIREMENTS

8. BINARY FISSION Little increase in size Growth in numbers to form colonies on an agar plate

9. How about these numbers!

10. BACTERIAL GROWTH

11. GROWTH PHASES

12. BIOLOGY 2250 PART 2. CONTROL OF MICROBES

13. TERMINOLOGY

14. MICROBIAL DEATH

15. Types of Cell Damage Alterations of Plasma Membrane Damage to Proteins and Nucleic Acids

16. PHYSICAL METHODS OF CONTROL Moist heat Dry heat Filtration High pressure Desiccation Osmotic pressure radiation

17. Moist Heat Autoclave

18. Principle of Autoclave Adjust your recipe to your altitude!

19. Dry Heat Oven Bunsen burner flame

20. FILTRATION Membrane filters have different pore sizes, e.g. 0.45 µ’s

21. High Pressures Fruit Juices

22. Desicattion Freeze Dried Foods Dried Meats Dried Fruits

23. Osmotic Pressure Salting – Pickling -

24. RADIATION Ionizing – cobalt, gamma rays Nonionizing – UV light Microwave

25. CHEMICAL CONTROL