Food Microbiology (30) Lecture

Question 1

Which grows fastest : yeast, bacteria, or mold?

Answer 1

bacteria

Question 2

What determines how fast bacteria grows?

Answer 2

Water activity (aw): measurement of the water available for an organism to grow from 07-1.
Pure water has activity measure of 1.0
crystals such as sugar have zero water
fresh meat have tons of water thus grow bacteria fastest
tons of bugs are around .9-1.0 water activity
Staphyloccus is around (.86)

Question 3

If you increase dideoxynucleotide concentration will that make longer or shorter fragments of DNA?

Answer 3

shorter

Question 4

Intrinsic factors that lead to the growth of microorganisms in food

Answer 4

water availability
pH
Nutrients
Biological barriers such as egg shells
Antimicrobial chemicals

Question 5

What are Extrinsic factors that lead to the growth of microorganisms in food?

Answer 5

temperature

atmosphere

Question 6

what is the enzyme in egg whites, tears and saliva

Answer 6

lysozeme

Question 7

Characteristics of Lactic Acid Bacteria

Answer 7

gram-positive, aerotolerant (grows with oxygen), obligate fermentors (they can switch between aerobic/anaerobic metabolism)

Question 8

What causes holes in cheese, bread?

Answer 8

CO2

Question 9

What is the Alcoholic Fermentation by Yeast process?

Answer 9

glucose - pyruvate - ethanol + CO2

Question 10

What do some GMOs have?

Answer 10

resistance genes to some of these toxic bacterias