Powerpoint 6

Question 1

Define fermentation related to the food industry

Answer 1

Conversion of sugar to alcohol or acids using microorganisms under anaerobic conditions

Question 2

How does yeast reproduce?

Answer 2

A process called “budding”

Question 3

What does yeast look like under a microscope?

Answer 3

Oval shaped
Clustered
Blue (from the blue stain)

Question 4

What kind of environments can yeast live in?

Answer 4

Anaerobic (causes yeast to ferment sugar to produce alcohol)
Aerobic (produces biomass of yeast cells)
Osmophilic (can grow in high sugar concentrations)

Question 5

Industrial uses of yeast

Answer 5

Used in production of:
Alcohol
Food
Vitamins
Saccharomyces cerevisiae is used 99% of the time (bakers yeast)

Question 6

Differentiate between wild and cultivated yeast
Why use cultivated over wild?

Answer 6

Wild yeast -
Natural yeast present on or in the fruit
Cultivated yeast -
S. Ellipsoideus is added to the juice

Cultivated over wild because wild is too unpredictable and cannot produce a consistent product (can also cause spoilage, off taste, odour…)
Cultivated can also tolerate a higher percent alcohol concentration

Question 7

Which organism can spoil wine?
What industrial product does the wine spoilage microbe make?

Answer 7

Acetobacter can spoil wine
An industrial product made by wine spoilage is - acetic acid

Question 8

How is brewing beer different than making wine?
What are two types of yeast used in the brewing industry?

Answer 8

Wine -
The fermentation of fruit juice
Beer -
The fermentation of malted grains
1. Saccharomyces cerevisiae
2. Saccharomyces carlsbergensis

Question 9

What are the names of lactic acid bacteria?

Answer 9

1. Streptococcus lactis
2. Lactobacillus casei
3. Lactobacillus bulgaris
4. Leuconostoc species

Question 10

What are starter cultures?
Why are they used instead of the background bacteria found in milk?
What are the functions of starter cultures?

Answer 10

Starter cultures -
Microbes added to milk to produce fermented products (cheese, yogurts, etc)
Used instead of background because background can be uncontrollable and unpredictable
Functions:
Primary function -
Lactic acid production from lactose
Other function -
Flavour, inhibit undesirable organisms

Question 11

What are the name of the organisms used as starter cultures in yogurt?
What is their purpose?

Answer 11

1. Lactobacillus lactis
2. Streptococcus thermophilus
3. Leucostonic lactis
   They produce fermentation and lactic acid, coagulating the protein to form a thin curd

Question 12

What are probiotics and why would they be added to fermented dairy products?

Answer 12

Microbes that are intentionally taken to promote health benefits

May be added to fermented diary products to enhance health benefits

Question 13

What is the difference between:
Old cheese and mild cheese?
Cheddar cheese and Swiss cheese?
Cheddar and blue cheese?

Answer 13

Old and mild -
Amount of lactic acid produced
Cheddar and Swiss -
Swiss is 2nd fermentation and bacterium is added to started culture to produce acid (gas holes produced)
Cheddar and blue cheese -
Blue mild is the 2nd fermentation with penicillin Roquefortii to encourage surface mold growth

Question 14

Examples of fermented foods

Answer 14

Kimchi and sauerkraut
Soya sauce
Dry sausages
Sourdough bread