EXERCISE 9

Question 1

Food preservation technology mediated by microorganisms

Answer 1

Fermentation

Question 2

Metabolic process of deriving energy from organic compounds without oxidizing agent

Answer 2

Fermentation

Question 3

Factors affecting fermentation (6)

Answer 3

Substrate
Solute Concentration
pH
Temperature
Aeration
Fermenting microorganism

Question 4

How to ferment vegetables

Answer 4

dry-salting or brining

Question 5

What are the reactants and products of fermentation

Answer 5

sugars and lactic acid

Question 6

Significance of Salting (4)

Answer 6

• 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

Question 7

Why is boiled rice water added to mustasa

Answer 7

adds dissolves carbohydrates which helps convert to lactic acid bacteria

Question 8

Why is mustasa put into a jar with plastic cover?

Answer 8

prevent oxygen which may reduce redox potentials + physical exclusion

Question 9

3 factors that favours growth of LAB

Answer 9

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

Question 10

When does growth of initial bacteria slow down or stop?

Answer 10

upon accumulation of acid, giving rise to LAB

Question 11

What is the medium of Lactic Acid Bacteria

Answer 11

de Man Rogosa and Sharpe Agar (MRSA AGAR)

Question 12

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

Answer 12

sodium acetate and ammonium citrate

Question 13

Color of LAB colonies

Answer 13

creamy to off white

Question 14

What does the presence of coliforms denote?

Answer 14

indicates presence of pathogenic microorganisms

Question 15

What is the medium of Coliforms

Answer 15

Violet Red Bile Agar

Question 16

VRBA

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

Answer 16

crystal violet and bile salts

lactose and neutral red

Question 17

Color of Coliform colonies

Answer 17

pink to red

Question 18

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

Answer 18

4.1

Question 19

What microorganisms do VRBA inhibit the growth of

Answer 19

Gram +

Question 20

What microorganism is responsible for fermentation in tempeh?

Answer 20

Rhizopus microsporus var. oligosporus

Question 21

How much acetic acid does vinegar contain?

Answer 21

4%

Question 22

Where is vinegar produced from?

Answer 22

acetous fermentation of ethanol

Question 23

What is the ph of vinegar

Answer 23

2.0 - 3.5

Question 24

2 distinct processes that result to VINEGAR

Answer 24

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

Question 25

What is tempeh

Answer 25

mold-fermented soybean

Question 26

What are the substrates used for fermentation of soybeans

Answer 26

lipids and proteins

Question 27

What does boiling do to fermentation of tempeh (3)

Answer 27

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

Question 28

formula for %TA

Answer 28

%TA = [(volume of titrant)(N of titrant)(molecular weight of lactic acid/1000)] - - - -- - -- - - - - - (volume of sample of barong mustasa) times 100

Question 29

What is the molecular weight of lactic acid

Answer 29

90

Question 30

Vinegar total composition (5)

Answer 30

1. alcohol 2. glycerin 3. esters 4. sugars 5. salts

Question 31

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

Answer 31

Backslop

Question 32

2 ways to prepare YEAST STARTER CULTURE

Answer 32

- increase # of yeast cells - shaking - aeration

Question 33

EFFECT of addition of sugar in Alcoholic fermentation

Answer 33

- increase concentration of fermentable hexoses in coconut water

Question 34

4 stages in Alcoholic fermentaion

Answer 34

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

Question 35

STAGES IN ALCOHOLIC FERMENTION what happens in STARTER CULTURE

Answer 35

- yeast strains is selected - inoculated into juice

Question 36

How is fermentation monitored in BUNG SET UP

Answer 36

formation of bubbles

Question 37

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

Answer 37

yes

Question 38

What types of organisms perform acetic acid fermentation?

Answer 38

obligate aerobes

Question 39

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

Answer 39

pure culture o r backslopping

Question 40

What happens in acetic acid fermetnation

Answer 40

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

Question 41

how to prepare TEMPEH FERMENTAITON (3)

Answer 41

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

Question 42

statutory limits for total coliform count in water

Answer 42

< 1.1 mpn/mL