Fermented foods

Question 1

What was fermentation used for?

Answer 1

Preserve food, enhance shelf life, increase safety
Improve flavour, texture

Question 2

What is the definition of fermented foods?

Answer 2

Foods or beverages produced through controlled microbial growth and the conversion of food components through enzymatic action

Question 3

Is fermented food a “functional food”?

Answer 3

Yes

Question 4

What are the two ways that fermented food originates?

Answer 4

Spontaneous and induced

Question 5

What is spontaneous fermentation?

Answer 5

Natural fermentation. The microorganisms are naturally present in the raw material or manufacturing environment.

Question 6

What is induced fermentation?

Answer 6

Microorganisms are added as a starter culture . The natural microflora is inefficient, uncontrollable, unpredictable or destroyed by heat treatment.

Question 7

How do you select the starter culture?

Answer 7

Selection based on the type and quality of the product
Incubation temperature during fermentation
Nutrient content

Question 8

Which important role does the food matrix play?

Answer 8

Plays a role in the survival of bacteria via its protective effect against gut conditions (pH, bile acids)

Question 9

Why is the starter culture added in high inocculum levels?

Answer 9

So that it will have low competition from other organisms

Question 10

What is the species used for producing yoghurt called?

Answer 10

Streptococcus thermophilus

Question 10

What are the basic characteristics of lactic acid bacteria?

Answer 10

Gram positive
Ferment sugars to lactic acid
Catalase negative
Non-motile
Unable to form endospores
Able to grow at low pH (below 5.5)
Non-pathogenic

Question 10

Which taxa are included in the functional concept “lactic acid bacteria”?

Answer 10

Lactococcus (sourmilk, cheese)
Lactobacillus (Spontaneously dominating most traditionally lactic acid fermented foods)
Leuconostoc (initial fermentation of plant material)
Oenococcus (wine, beer)
Pediococcus (smoked fermented sausage, fermented vegetables, cereals, beer)
Weissella (Spontaneous in many lactic acid fermenting foods)

Species: Streptococcus thermophilus (starter culture youghurt)

Question 11

Which species are often mistaken for lactic acid bacteria but isn’t actually?

Answer 11

Bifidobacterium, Enterococcus, Carnobacterium

Question 11

Why is enterococcus not LAB?

Answer 11

Because it causes urinary tract infections and easily acquires antibiotic resistance
Can cause sepsis

Question 12

Give some examples of fermented foods

Answer 12

Kefir
Kombucha
Sauerkraut
Tempeh
Kimchi
Sourdough bread

Question 13

Are fermented foods and probiotics closely related?

Answer 13

Yes

Question 14

What is the WHO definition of probiotics?

Answer 14

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

Question 15

Hosw many bacteria do fermented foods typically contain?

Answer 15

10^5-7

Question 16

How many LAB do dairy products contain?

Answer 16

10^9

Question 17

Do fermented food products contain live bacteria?

Answer 17

Not when heated, may also not have survived because of harsh environment

Question 18

What must the microorganisms in the product manage to survive from in the product?

Answer 18

Salt
Organic acids
Ethanol
Anaerobic milieu
Low pH

Question 19

What does allochtonous mean?

Answer 19

Foreign

Question 20

What is the transient microbiota?

Answer 20

Part of the variable microbiome that varies with diet. Can be detected for a few days but not after one week

Question 21

The human microbiome is made up from a transient and a _____ community

Answer 21

Core commensal community

Question 22

What in the fermented product enhances the activity of the microbial enzymes (amylases, proteases, phytases, lipases)?

Answer 22

The acidic nature of fermented products

Question 23

What do the microbial enzymes do?

Answer 23

Modify primary food products through hydrolysis of polysacharrides, proteins, phytates and lipids

Question 24

Give examples of some nutritional benefits of fermentation

Answer 24

Synthesise complex vitamins
Release nutrients from indigestible cellulosic and hemicellulosic structures surrounding endosperm in grain and seed making them available for humans to digest

Question 25

Can LAB produce lactase to digest lactose?

Answer 25

Yes

Question 26

What are phytate?

Answer 26

They form insoluble complexes with minerals (iron, zinc, calcium, magnesium) and is abundant in cereal grains, oil seeds, legumes, flours