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MICROBIOLOGY > EXERCISE 9 > Flashcards

EXERCISE 9 Flashcards

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1
Q

Food preservation technology mediated by microorganisms

A

Fermentation

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2
Q

Metabolic process of deriving energy from organic compounds without oxidizing agent

A

Fermentation

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3
Q

Factors affecting fermentation (6)

A

Substrate
Solute Concentration
pH
Temperature
Aeration
Fermenting microorganism

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4
Q

How to ferment vegetables

A

dry-salting or brining

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5
Q

What are the reactants and products of fermentation

A

sugars and lactic acid

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6
Q

Significance of Salting (4)

A
  • adds flavour
  • inhibits PECTINOLYTIC ENZYMES to maintain crisp texture
  • selective to Lactic Acid Bacteria growth due to higher salt tolerance
  • facilitates osmosis of sugars and nutrients
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7
Q

Why is boiled rice water added to mustasa

A

adds dissolves carbohydrates which helps convert to lactic acid bacteria

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8
Q

Why is mustasa put into a jar with plastic cover?

A

prevent oxygen which may reduce redox potentials + physical exclusion

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9
Q

3 factors that favours growth of LAB

A
  1. addition of salt
  2. production of lactic acid lowers pH, inhibiting growth of other organisms
  3. produces CO2 which contributes to anaerobic environment
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10
Q

When does growth of initial bacteria slow down or stop?

A

upon accumulation of acid, giving rise to LAB

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11
Q

What is the medium of Lactic Acid Bacteria

A

de Man Rogosa and Sharpe Agar (MRSA AGAR)

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12
Q

what is present in MRSA that inhibit growth of other organisms EXCEPT for LAB (2)

A

sodium acetate and ammonium citrate

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13
Q

Color of LAB colonies

A

creamy to off white

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14
Q

What does the presence of coliforms denote?

A

indicates presence of pathogenic microorganisms

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15
Q

What is the medium of Coliforms

A

Violet Red Bile Agar

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16
Q

VRBA

  • inhibitory components (2)
  • indicator system (2)
A

crystal violet and bile salts

lactose and neutral red

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17
Q

Color of Coliform colonies

A

pink to red

18
Q

during fermentation, acid development is carefully monitored until what pH level

A

4.1

19
Q

What microorganisms do VRBA inhibit the growth of

A

Gram +

20
Q

What microorganism is responsible for fermentation in tempeh?

A

Rhizopus microsporus var. oligosporus

21
Q

How much acetic acid does vinegar contain?

A

4%

22
Q

Where is vinegar produced from?

A

acetous fermentation of ethanol

23
Q

What is the ph of vinegar

A

2.0 - 3.5

24
Q

2 distinct processes that result to VINEGAR

A
  1. ethanolic fermentation by yeasts
  2. production of acetic acid from ethanol by acetic acid bacteria
25
Q

What is tempeh

A

mold-fermented soybean

26
Q

What are the substrates used for fermentation of soybeans

A

lipids and proteins

27
Q

What does boiling do to fermentation of tempeh (3)

A
  1. enhances extraction of soluble nutrients
  2. inactivates microorganisms that might interfere with fermentation
  3. denatures trypsin inhibitor (anti-nutritional factor soy protein)
28
Q

formula for %TA

A

%TA =

[(volume of titrant)(N of titrant)(molecular weight of lactic acid/1000)]
- - - – - – - - - - -
(volume of sample of barong mustasa)

times 100

29
Q

What is the molecular weight of lactic acid

A

90

30
Q

Vinegar total composition (5)

A
  1. alcohol
  2. glycerin
  3. esters
  4. sugars
  5. salts
31
Q

a fermentation technique that involves adding a small amount of a previous ferment to a new one

A

Backslop

32
Q

2 ways to prepare YEAST STARTER CULTURE

A
  • increase # of yeast cells
  • shaking - aeration
33
Q

EFFECT of addition of sugar in Alcoholic fermentation

A
  • increase concentration of fermentable hexoses in coconut water
34
Q

4 stages in Alcoholic fermentaion

A
  1. addition of sugar
  2. starter culture
  3. conversion of sugars to ethanol
  4. bung set-up
35
Q

STAGES IN ALCOHOLIC FERMENTION

what happens in STARTER CULTURE

A
  • yeast strains is selected
  • inoculated into juice
36
Q

How is fermentation monitored in BUNG SET UP

A

formation of bubbles

37
Q

In bung set up, is O2 levels limited to be exposed against fermenting liquid

A

yes

38
Q

What types of organisms perform acetic acid fermentation?

A

obligate aerobes

39
Q

In acetic acid fermentation, fermentation is initiated by either (2)

A

pure culture o r backslopping

40
Q

What happens in acetic acid fermetnation

A

ethanol is oxidized back to acetaldehyde; acetaldehyde is further oxidized to acetic acid

41
Q

how to prepare TEMPEH FERMENTAITON (3)

A
  1. R. oligosporus spore suspension is added directly to the beans
  2. using dried tempeh culture that serves as backslop material
  3. use of “usar” which is made by inoculating wild Rhizopus spores onto surface of
    Hibiscus plant
42
Q

statutory limits for total coliform count in water

A

< 1.1 mpn/mL

MICROBIOLOGY (30 decks)

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