OLEARY L4 Fungi

Question 1

Process of fungi in food production?

Answer 1

• Yeast (Saccharomyces cerevisiae) converts glucose to alcohol

glucose - 2 pyruvate - 2 acetylaldehyde - 2 ethanol

Question 2

What is the yeast conversion of glucose to alcohol called?

Answer 2

Fermentation

Question 3

What is the stirrer used for?

Answer 3

To keep the microorganisms, nutrients and temperature evenly distributed

Question 4

What are probiotics?

Answer 4

Live microorganisms that when administered in adequate amounts, confer a health benefit on the host

Question 5

What are examples of beneficial probiotic strains?

Answer 5

-Lactobacillus acidophiles
-Bifidobacterium longum

Question 6

What are bacterial spoilage effects?

Answer 6

-Texture/taste
-Gas/swollen packaging and cxans
-Off odours
-Slime

Question 7

Fungal spoilage?

Answer 7

-Moulds visible
-Texture/ structure
-Off odours or flavours
-Gas

Question 8

What are the conditions needed for bacterial growth?

Answer 8

FATTOM
Food - prefer high protein foods like meat, dairy products, cooked veg
Acidity - pH between 4.6-7.6 for growth
Temp - danger zone is 41-135 degrees
Oxygen
Moisture/water

Question 9

What displaces oxygen?

Answer 9

nitrogen gas

Question 10

What is a foodborne illness?

Answer 10

Any illness arising from the consumption of contaminated food

Question 11

What are some features of P.expansum and A.flavus?

Answer 11

-2 major food spoilage fungi
-No active spore dispersal mechanism
-2-3um spores act like fine dust carried by air turbulence
-Unwettable, resist dessication and UV radiation

Question 12

What are some features of Fusarium graminearum?

Answer 12

-Major plant pathogen
-Wettable - dispersed by rain droplet impact

Question 13

Which fungi twist and collapse ejecting spores as humidity increases?

Answer 13

Cladosporium

Question 14

Which fungi fire ballistospores into the air as humidity increases at hight hours?

Answer 14

Mirror yeast

Question 15

Features of moulds?

Answer 15

Exist as multicellular, filamentous colonies
-Favour solid surfaces
-Mostly asexual spores
-Aerobic or faculative anaerobes

Question 16

Features of yeasts?

Answer 16

-Exist as unicellular, filamentous colonies
-Favour liquid environments
-Mostly sexual reproduction
-Aerobic or faculative anaerobes
-Dimorphic can exist as mould or yeast e.g penicillium marneffei

Question 17

What is an example of a dimorphic fungi?

Answer 17

Penicillium marneffei

Question 18

Do moulds grow well in low nutrient environments?

Answer 18

Yes they are much less fastidious than bacteria

Question 19

What is the dgeree of aw tolerance?

Answer 19

The minimum level at which germination and growth can occur

Question 20

What are moulds usually - temp wise - what moulds can grow at a high or low temp

Answer 20

Most moulds are mesophilic
-Cladosporium can grow at -7 (also fusarium, penicillium)
Aspergillus can grow up to 60 degrees