PPT 1 (SLIDE 1-41)

• FOOD

  any nutritious substance that people or animals eat or drink or that plants absorb in order to maintain life and growth.
• MICROBIOLOGY

  The branch of science that deals with microorganisms.
• Food Presrvation Method

  1. Cheese
  2. Bread
  3. Summer Sausage
  4. Beer
  5. Sauerkraut
• 900AD

  • Food Poisoning Recognized
  • Emperor Leo VI of Byzantium - Issued an edict
• GREEKS AND ROMANS - 1582

  • Ergotism
  • Claviceps purpurea – Rye
• Ergotism

  • Convulsive ergotism muscle twitching and spasms, changes

  in mental state, hallucinations, sweating, and fever lasting for several weeks
• Gangrenous ergotism

  • holy fire or St. Anthony’s fire
  • mild limb pain followed by burning pain shooting through the affected limbs
  • limbs become numb and painless.
  • Turns to darker color
  • Autoamputate
• 1795

  • Nicholas Appert
  • Father of Canning
• Canning

  • method of preserving food from spoilage by storing it in containers that are hermetically sealed and then sterilized by heat.
• 1854-1864

  • Louis Pasteur
  • discovered scientific basis for preservation methods-FOOD MICRO BECOMES a SCIENCE
• Why do we study food microbiology

  • Provide Clean, Safe, Healthful Food to Consumer
  • Prevent Food Spoilage
  • Prevent Food-borne Illnesses
  • Food Preservation and Production
• FOOD SAFETY

  Divided into causative categories called “hazards”
• Biological Hazards - bacteria, molds, natural occurring toxins
• Chemical Hazards – chemicals like petroleum, herbicides, pesticides, heavy metals.
• Physical Hazards – glass, rocks, wood splinters
• Microorganisms are important in many different ways:

  • Pathogenic, or disease-causing, microorganisms can cause illness
  • Spoilage microorganisms cause a food to smell, taste, and look unacceptable
  • Fermentation microorganisms produce a desired food product
  • Other microorganisms do nothing in foods
• Bacteria can be classified in a number of ways.

  *Their shape

  • Round=cocci
  • Elongated=rods
• Sporeformers

  • Some rod shaped bacteria
  • These spores have the ability to survive a wide range of environmental extremes.
  • They can survive heating up to 100C and are resistant to most chemicals including sanitizing solutions.
  • The most noteworthy sporeformer is Clostridium botulinum.
• Spores - dormant state

  • Much more resistant to environmental stresses (heat, cold, chemicals)
• Vegetative state - active state

  • More susceptible to inactivation
• PSYCHROPHILE

  • Grow from 1-20C
  • EXAMPLES: Pseudomonas, Flavobacterium, Alcaligenes
• PSYCHROTROPHIC:

  • Grow best at 37C, but can grow at refrigeration (3-7C)
  • EXAMPLE: Listeria monocytogenes
• MESOPHILE:

  • Optimum temperature 20-40C
  • Group containing most human pathogens
  • EXAMPLES: E. coli, Salmonella, Clostridium botulinum
• THERMOPHILE:

  • Optimum temp >45C
  • EXAMPLE: Bacillus stearothermophilus
• Low Temperatures

  • Refrigeration (40-45F) slows or stops bacterial growth
  • Freezing stops bacterial growth
• High Temperatures

  • Heating (165F or higher) destroys bacteria for immediate service foods served in restaurants and homes.
  • Thermal processing of shelf stable foods (180 - 250F) destroys bacteria for longer shelf-life foods – temperature dependent upon product acidity
• Low acid canned foods

  • inactivation of C. botulinum
• Growth of Bacteria

  • Binary Fission
• Controlling Growth

  • F - Food
  • A - Acidity
  • T - Temperature
  • T - Time
  • O - Oxygen
  • M - Moisture
• Food – Nutrients Content

  • For growth, microorganisms require the following:

  1. Water
  2. Source of energy
  3. Source of nitrogen
  4. Vitamins & related growth factors
  5. Minerals
• Food Acidity

  • Optimal pH for growth: 6.0 – 8.0
  • Disease causing bacteria: 4.6 - 9.5
  • Spoilage bacteria: 1.5 - 9.5
• Temperature

  • Thermophiles – like hot conditions
  • Mesophiles – like warm conditions (around body temperature)
  • Psychrotrophs – can grow at refrigeration temperatures
  • Most pathogens are mesophile
• Temperature Classification

  • Psychro - cold
  • Meso - middle
  • Thermo - warm
  • Trophic - growing
  • Duric - withstand
  • Phil or philic - prefers or loves
• Temperature Danger Zone

  • 5C - 57C
• Reproduction of Bacterial Cells

  • Reproduced by division
  • Referred to as “growth”
  • Under optimum conditions a cell divides every
  • 20-30 minutes