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Fermentation Flashcards

(65 cards)

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1
Q

What is the definition of fermentation according to Louis Pasteur?

A

Life without air

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2
Q

What are some reasons to ferment products? (name 4)

A

Food safety
Shelf life extension
Nutritional value
Texture
Aroma
Taste
Appearance

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3
Q

What are the two non-food preservation related reasons to ferment food?

A

Abundant in human diet
Sustainable and natural

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4
Q

What are the three ingredients in a fermentation process?

A

Food components
Microorganisms
Water

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5
Q

What are the three types of operations when fermenting products?

A

Physical
Biological
Thermal

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6
Q

What are the five main types of fermentation?

A

Alcoholic
Lactic
Propionic
Alkaline
Acetic

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7
Q

What are the three most common workhorses in fermentation?

A

Lactic acid bacteria
Yeasts
Moulds

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8
Q

What type of intrinsic factors do enzyme activities add to fermented products?

A

Digestibility
Flavour
Taste
Acid formation

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9
Q

What are the four types of metabolites formed in fermented products?

A

Flavour compounds
Colouring substances
Vitamins
Antimicrobial compounds

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10
Q

What are the two ways to use microorganisms to ferment?

A

Natural fermentation or with defined starters

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11
Q

What are the pros and cons of natural fermentation?

A

Pros: Simple, small scale and low cost
Cons: unpredictable quality, failures (contamination with pathogens or spoilers), can be slow

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12
Q

What is back-slopping?

A

Grabbing microorganisms from the fermented food and adding it to the raw material

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13
Q

What are the pros and cons of fermenting with defined starters?

A

Pros: Predictable, constant and effective
Cons: expensive, only feasible at large scale

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14
Q

What are two products you can make with alcoholic fermentation?

A

Beer
Wine
Bread

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15
Q

Which m.o. is used for alcoholic fermentations?

A

Yeast

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16
Q

Which mechanism is used in the first step of alcoholic fermentation?

A

Common glycolysis

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17
Q

What is the end product of the first step of alcoholic fermentation?

A

Pyruvic acid

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18
Q

What is the final product of alcoholic fermentation?

A

Ethanol

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19
Q

What m.o. is used for lactic acid fermentations?

A

Lactic acid bacteria

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20
Q

What are the two types of lactic acid fermentation?

A

Homofermentative and heterofermentative

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21
Q

What are the two types of homofermentative lactic acid bacteria?

A

Homolactic fermentation
Mixed acid fermentation

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22
Q

What is the key enzyme in homo-fermentation?

A

Aldolase

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23
Q

What is the key enzyme in hetero-fermentation?

A

Phosphoketolase

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24
Q

What products are formed from mixed acid fermentation?

A

Lactate
Acetate
Formate
Ethanol

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25
What yields more ATP? Homolactic or mixed acid fermentation?
Mixed acid fermentation
26
What does the strain of lactic acid bacteria determine?
Functionality Aroma Acidification
27
What is the m.o. involved in propionic fermentation?
Propionic acid bacteria
28
What are the final products of propionic fermentation?
Propionic acid Acetic acid CO2
29
What other m.o. is used (besides prionic acid) to make cheese?
Lactic acid bacteria
30
What are the m.o.’s used for acetic fermentation?
Acetic acid bacteria and yeast
31
What are the two stages of acetic fermentation?
Conversions of sugars into ethanol Ethanol into acetic acid
32
True or false: the second step of acetic fermentation is when the product is fermented?
False
33
What is the intermediate product of acetic fermentation?
Acetaldehyde
34
What are the steps in sauerkraut production?
Remove outer leaves Shredding Adding salt Packing Sealing Main fermentation Secondary fermentation
35
Why is salt added to sauerkraut?
Selective effect on microbiota Inhibits pectinolytic enzyme Extracts cabbage juice
36
What are the two types of fermentation that take place?
Hetero and homo fermentative fermentation
37
What happens during heterofermentative fermentation?
Acids are formed and pH goes down
38
What happens during homofermentative fermentation?
Acidity is increased and aroma compound formation
39
What is the pH of sauerkraut?
3.4-3.6
40
What are the potential production problems that can arise? What are the causes for these?
Pink/grey discoloration-> NaCl or temp too high, air leakage Grey discoloration-> gram negative bacteria Too soft-> not enough salt or too high pressure Off taste-> temperature Surface spoilage-> yeast through air leakage Putrefaction-> presudomonas
41
What is the difference in shelf life between not fermented and fermented meat?
Days to weeks to months
42
What are the steps in the process of fermented sausage production?
Cutting Tubing Incubation Smoking Drying
43
What are the steps of the actual fermentation of sausages?
Acidification Maturation
44
What is the role of Micrococcus in sausage fermentation?
Nitrite formation to prevent spoilage
45
What is the role of LAB in sausage fermentation?
Acidification Flavour
46
What compound binds to myoglobin to make the meat stay red?
Nitrous Oxide (NO)
47
What are the steps of beer production?
Malting Brewing Primary fermentation Maturation lagering
48
What is the role of malting barley in beer production?
Activate amylases and proteases
49
What is the role of mashing malt in beer production?
Liberate fermentable sugars
50
What is the product from primary fermentation in beer production?
Ethanol
51
What is formed during maturation in beer production?
Flavour
52
What microorganism is used for beer making? What two sources can you get this from?
Yeast from freeze dried material or liquid suspension
53
What ingredients and microorganisms are involved in kinema production?
Soybeans Bacillus
54
What are the advantages and disadvantages of using soybeans?
Pros: High in protein and favourable amino acid composition Cons: Bitter, antinutritional factors
55
What are the steps in the production process of kinema?
Soaking Boiling Crushing Packaging Incubation
56
What type of fermentation is involved in kinema production?
Alkaline fermentation
57
What is the key step in kinema production? Why?
Boiling Enriches for spore formers-> bacilli abundance
58
What ingredients and microorganisms are involved in tempeh production?
Soybeans and other beans + cereals Rhizopus oligosporus
59
What are the steps in tempeh production?
Soaking Dehulling Cooking Draining Inoculation Packaging Incubation
60
What nutrients increase in concentration in tempeh production? what decreases?
Increases: Nitrogen Fatty acids Fibre Dry matter Decreases: crude lipid
61
What ingredients and microorganisms are involved in soy sauce production?
Soybeans and wheat Aspergillys + yeast+LAB
62
What are the steps in soy sauce production?
Koji stage and moromi stage
63
What is the koji stage in soy sauce production?
Inoculation with koji moulds
64
What is the moromi stage in soy sauce production?
Inoculation with LAB and yeasts
65
Which are koji molds?
Aspergillus oryzae, Rhizopus spp.

Food Microbiology (4 decks)

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