Microbes and Food and Preserving Food 17.2

17.2 Preserving Food

1) You are writing a recipe for bottling fruit. Which stages would you stress to make sure that the fruit would keep well?

I would stress closing the container and refridgeration.

2) Why can dried fruit be kept for much longer than fresh fruit?

Moisture is what bacteria can live on, and when something is dried, it needs a while to retain moisture again, taking longer time to spoil.

3) ‘Steak tartare’ (minced steak mixed with egg yolk) is eaten raw.

a) What are the dangers of eating raw meat and eggs?

Raw foods are prone to bacteria, while cooking can actually kill bacteria.

b) Which of the above methods could be used to kill the bacteria in the meat? (Heating isn’t allowed!)

Irradiation is probably the most useful method in such a case.

4) Chickens and turkey contain salmonella bacteria

a) Do frozen chickens and turkeys contain these bacteria?

Yes they do, because freezing does not kill bacteria, it merely slows its growth.

b) Why is it important to let the bird thaw out completely before cooking it?

If you don’t completely thaw out the bird, the inside will remain raw after cooking, so the chicken will have microbes on the inside still.

5) Why is it dangerous to thaw frozen meat and then refreeze it without cooking?

When food is completely unfrozen, dangerous bacteria can begin to [quickly] grow on it, and because a freezer does not kill bacteria, if you unfreeze meet then refreeze it again, there is still danger of bacteria being there.

17.2 Microbes and Food

1) List the main types of microbe and their effects.

a. Fungi (important in eating)

b. Bacteria (can help you with vital processes, can make you sick)

c. Algae (provide a lot of the oxygen we breathe)

d. Viruses (Make you sick)

e. Protozoa (feed on material, decompose)

2) Make a list of foods which use fungi in their production. Try to find out others not mentioned here.

1. Artificial Citric Acid

2. Vitamins

3. Soy sauce

4. Processed meat products

3) Name a fungus you can eat which isn’t a microbe

Mushroom

4) What would be an alternative way of producing bubbles in bread

Pumping oxygen in manually, but that would be very painstaking.

5) Try to find out other types of food which use bacteria in their production

1. Butter

2. MSG (monosodium glutamate)

3. Alcoholic drinks

4. Kefir