Control of Microorganisms in food include these methods:

1) Pasteurization
2) Freezing & Refrigeration
3) Radiation
4) Canning

5) Chemicals

6) High Osmotic Pressure

7) Drying and Dessication

Pasteurization:

• Mechanism of Action: protein denatures
  
  

• Use: heat treatment for milk that kills all pathogens and most non-pathogens

Freezing & Refrigeration:

• Mechanism of Action: Freezing & Refrigeration = decrease chemical reactions and poss. change in proteins
  
  

• Use:Effective method for preserving microbial cultures, in which cultures are quickly frozen

Radiation:

• Mechanism of Action: Ionizing= Destruction of DNA,

                                      Nonionizing= Damage of DNA

• Uses: Ionizing- not widespread routine

                Non-Ionizing- radation is not very penetrated

Canning:

• Mechanism of Action: many industries have standards for amount of thermophilic bateria allowed

•  Uses: If canned foods are exposed to high heat temps, the thermophilic bacteria that we commercially standardized for saftey can reappear causing food spoilage

Food Microbiology: Use of Microorganisms

Dairy Products:

1. Milk: Sterlile when in udder
   
   
2.  Cheese:
   - Seperates whey (liquid) from protein curd (casein)
   - Use S.lactis and S.cremoris to produce latic acid
   - Cheese classified according to hardness
   - Inoculated with additional microbes to produce various
     types if cheese

Food Microobiology: Use of Microorganisms

Dairy Products (Continued)

3) Butter: fat globules

- Leuconstoc sp.- produces diacetyls

- Requires: S. lactis & S.cremoris

4) Buttermilk- like butter, but use skim milk & microbe

5) Yogurt: low fat evaporated milk

- Lactobacillus & S. thermophilus

6) Kefir & Kumiss- Milk fermented with yeast

 Food Microbiology: Use of Mircroorganisms

Non- Dairy Products:

1. Bread: Made with yeast, CO2 makes bread rise
   
   
2. Sauerkraut, Pickles, Olives: made with Leuconstoc & Lactobacill.
   
   
3. Soy Sauce: made with Aspergillus oryzae

 Food Microobiology: Use of Microorganisms

Beverages

1.  Cider: apples contain sugars and yeast
   
   
2. Vinegar: -Acetobacter or Gluconobacter
   - Made from cide or wine
   - Converts ethanol to acetic acid
   
   
3. Alcoholic Beverages: -Beer=barley or other carbohydr. -Wine=grape -Sake=rice
   -Rum=sugar cane
   -Vodka=potatoes
   

Food Microobiology: Use of Microorganisms

Single Celled Protein: (SCP)

• Microbes are high in protein
  
  
• Supplement diet with microbes
  
  
• Used in: Animal foddes (animal food)
  
  
• Torula sp.(yeast) and certain bacteria used.

Industrial Microbiology-

Amino Acid Production:

1) Glutamic Acid:

- 600,000 tons/year

- Food condiment

- MSG~ food allergies

- Produced by~ Micrococcus and Corynebacterium glutamicum

2) Lysine:

- 70,000 tons/year

- 30% used for industrial purposes

 Industrial Microbiology-

Citric Acid Production:

• 300,000 tons/year

• Aspergillus niger converts: molasses to citric acid

• 70% used in the food industry; 30% used for industrial purposes

Industrial Microbiology-  

Enzymes:

1) Proteases: break down proteins

- Aspergillus sp. & Bacillus sp.

-Detergents, meat tenderizers, leather production, chill-proffing beer

2) Amylases: break down starches

- Aspergillus sp. & Bacillus sp.

 3) Lactase: break down lactose
     -Yeast

Industrial Microbiology-

 Antibiotic Prodution:

1) Fungal Sources:

- Penicillium & Cephalosporium

- Penicillin, cephalothins, and griseofluvin

 2) Bacterial Sources:

- Bacillus sp.- bacitracin & polymyxin

- Streptoyces sp.- streptomycin, tetracycline, amphotercin, chloramphenicol

Industrial Microbiology-

 Agricultural Uses:

1) Rhizobium: Nitrogen fixation

- Symbiotic realtion with~ legumes

- Mixed with peat moss to retain moisture and then seeded with legumes to ensure infection of the plant

 2) Bacillus thuringiensis (Bt)

- Microbe eats mosquito larvae

- Used in~ Municipal Control® programs & home gardeners

Alternative Energy Sources:

 1) Biomass: organic matter produced by living organisms including crops, waste, & trees

 2) Bioconversion: using microbes to convert biomass

3) Biofuels: ethanol from agricultural crops

Genetic Engineering:

1) Recombinant DNA- any artificial manipulation of genes within a species or between diff. species

2) Restriction Enzymes- enzymes that cut DNA into pieces that are easy to recombine in-vitro

3) Vector- plasmid or virus that inserts genes into a cell

4) Clone- genetically identical cells

Medical Therapy:

• Human insulin~ E.Coli carries human gene that makes this hormone
  
  
•  Human Growth Hormone (Somatostatin)
  
  
• Hep. B. Vaccine~ yeast carries VIRAL gene

Gene Theapy:

1. Replace: defective or mutated gene
   
   
2. Cystic Fibrosis: inhalation of a harmless cold virus that carries the healthy gene that the person lacks
   
   
3. Agammaglobulinemia: inability to produce Anti-Bodies
   
   
4. Addition of: genetically engineered virus to the bone marrow

 Genetic Engieering: Applications

Agricultural Uses:

• Bovine Growth Horomone (BGH)
  - E. Coli carries gene
  - Gene for pest resistance inserted into plants
  - Insertion of N-fixation genes into plants