Food safety

Question 1

Which has more salt tolerance, homofermentative LAB or heterofermentative LAB?

Answer 1

Homofermentative LAB

Question 2

Name at least 3 antimicrobial factors associated with fermenting micro-organisms.

Answer 2

1. Decreasing pH
2. Increasing osmotic pressure
3. Ammonia
4. Bacteriocins
5. Carbon dioxide
6. Hydrogen peroxide
7. Diacetyl (more effective against gram negative than postive)

Question 3

What does M.I.D. stand for?

Answer 3

Minimal infective dose

Question 4

What are food borne infections in cheese, meat, fish and cereals?

Answer 4

Cheese:
1. Listeria monocytogenes
2. Salmonella
3. Escherichia coli

Meat
1. Salmonella

Fish
1. Listeria monocytogenes

Cereal
1. Eneterobacteriaceae

Question 5

What are some toxins to consider in the raw material?

Answer 5

1. Pesticides
2. Herbicides
3. Lead (this can leach is stored in containers with lead and as pH is low lead leaches)
4. Mycotoxins

Question 6

How can fermentation decrease mycotoxins toxicity? And how could this toxicity be completely broken down?

Answer 6

LAB can convert alfatoxin B1 to alfatoxin B2a which is less toxic. In order to removes completely toxicity the LACTONE RING has to be broken down and some Rhizopus species can do it.

Question 7

How can one prevent the formation of bongkrek acid?

Answer 7

By high inoculum amounts of Rhizopus oligosporus or incorporation of salt and low pH

Question 8

What are the two toxic by products discussed in the lect?

Answer 8

1. Ethyl carbamate -> carcinogenic and mutagenic
2. Biogenic amines -> mild toxicity and diverse range of adverse health effects

Question 9

How can u deal with ethyl carbamate?

Answer 9

Cannot really do much as it comes along with alcohol. No real conclusion on effect on humans.

Question 10

How can u deal with biogenic amines and how are this produce?

Answer 10

Produce by decarboxylation by decarboxylase of amino acids into biogenic amine + CO2.
This can be prevented by:
1. pasteurizing the raw material
2. hygienic practices
3. selection of starters with low decarboxylase activity.

Question 11

Why are fermented food safe and why not safe?

Answer 11

Safe:
1. Competitive microbiota. Good microbiota takes over.
2. Production of antimicrobial metabolites
3. Detoxification mechanism in some cases

Not safe:
1. Toxic by products
2. Production of toxic metabolites requires monitoring
3. Less stable than canned food.

Question 12

How is the method of decrease the pH fast called?

Answer 12

Back slopping technique