Microorganisms and Food

Question 1

What ways can microorganisms spoil food?

Answer 1

 Visible growth n food. Colonies of growth on bread e.g. Mucor/Pencillium.
 Release enzymes onto the food, eventually reduced to mush.
 Release toxins onto the bread. Clostridium botulinum produces botulin.
 Presence of some microorganisms can cause infection e.g. salmonella which attack lining of the stomach.

Question 2

What are the treatments to food spoilage?

Answer 2

 Cooking – Denatures enzymes/other proteins, killing microorganisms.
 Pasteurising – Heating to 72 C for 15 seconds, and cooling to 4 C – kills’ microorganisms.
 Drying, salting and coating in sugar – Dehydrate microorganisms.
 Smoking – Develops a hardened, dry outer surface, and smoke contains antibacterial chemicals.
 Pickling – An acid pH to kill microorganisms denaturing their enzymes/reproduction is slow.
 Irradiation – Kills microorganisms disrupting their DNA structure.
 Cooling/Freezing – Retards enzyme activity, meaning growth/reproduction is very slow.

Question 3

What does Lactobacillus do in the production of milk?

Answer 3

Lactobacillus forms lactic acid in milk, coagulating mixture.

Question 4

How does bread rise?

Answer 4

Bread rises by yeast, bubbles rising by release of carbon dioxide.

Question 5

What can Candida and such like be used for?

Answer 5

Kloyveromyces, Scytalidium, and Candida – Produce protein with a similar amino acid profile to animal/plant protein.

Question 6

What are the advantages of using microorganisms?

Answer 6

Faster, fluctuation in production for demand; no animal welfare issues, good protein source for vegetarians; no animal fat/cholesterol; SCP could be combined waste.

Question 7

What are the disadvantages of using microorganisms?

Answer 7

People may not want to eat fungi grown on waste, difficulties isolating the protein, protein has to be uncontaminated, infection – conditions are ideal for pathogens to grow, palatability – does not have the same taste/texture.