A) Unit Seven – Flashcards

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Control of Microorganisms in food include these methods:

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

5) Chemicals

6) High Osmotic Pressure

7) Drying and Dessication


 

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Pasteurization:

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  • Mechanism of Action: protein denatures

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

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  • 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
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Radiation:

 

 

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  • Mechanism of Action: Ionizing= Destruction of DNA,

                                      Nonionizing= Damage of DNA


  • Uses: Ionizing- not widespread routine

                Non-Ionizing- radation is not very penetrated

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Canning:

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  • 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
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Food Microbiology: Use of Microorganisms


Dairy Products:

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  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
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Food Microobiology: Use of Microorganisms


Dairy Products (Continued)

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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

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 Food Microbiology: Use of Mircroorganisms

 

Non- Dairy Products:

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  1. Bread: Made with yeast, CO2 makes bread rise

  2. Sauerkraut, Pickles, Olives: made with Leuconstoc & Lactobacill.

  3. Soy Sauce: made with Aspergillus oryzae
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 Food Microobiology: Use of Microorganisms


Beverages

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  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

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Food Microobiology: Use of Microorganisms


Single Celled Protein: (SCP)

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  • Microbes are high in protein

  • Supplement diet with microbes

  • Used in: Animal foddes (animal food)

  • Torula sp.(yeast) and certain bacteria used.
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Industrial Microbiology-

 

Amino Acid Production:

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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

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 Industrial Microbiology-

 

Citric Acid Production:

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  • 300,000 tons/year
  • Aspergillus niger converts: molasses to citric acid
  • 70% used in the food industry; 30% used for industrial purposes
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Industrial Microbiology-  

 

Enzymes:

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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

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Industrial Microbiology-

 

 Antibiotic Prodution:

 

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1) Fungal Sources:

- Penicillium & Cephalosporium

- Penicillin, cephalothins, and griseofluvin


 2) Bacterial Sources:

- Bacillus sp.- bacitracin & polymyxin

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

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Industrial Microbiology-

 

 Agricultural Uses:

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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

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Alternative Energy Sources:

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 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

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Genetic Engineering:

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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

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Medical Therapy:

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  • Human insulin~ E.Coli carries human gene that makes this hormone

  •  Human Growth Hormone (Somatostatin)

  • Hep. B. Vaccine~ yeast carries VIRAL gene
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Gene Theapy:

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  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
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 Genetic Engieering: Applications


Agricultural Uses:

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  • Bovine Growth Horomone (BGH)
    - E. Coli carries gene

    - Gene for pest resistance inserted into plants

    - Insertion of N-fixation genes into plants
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