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 (3)

Answer 6

• adds flavour
• inhibits PECTINOLYTIC ENZYMES to maintain crisp texture
• selective to Lactic Acid Bacteria growth due to higher salt tolerance

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

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

Color of Coliform colonies

Answer 16

pink to red

Question 17

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

Answer 17

4.1

Question 18

What microorganisms do VRBA inhibit the growth of

Answer 18

Gram +

Question 19

What microorganism is responsible for fermentation in tempeh?

Answer 19

Rhizopus microsporus

Question 20

How much acetic acid does vinegar contain?

Answer 20

4%

Question 21

Where is vinegar produced from?

Answer 21

acetous fermentation of ethanol

Question 22

What is the ph of vinegar

Answer 22

2.0 - 3.5

Question 23

2 distinct processes that result to VINEGAR

Answer 23

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

Question 24

What is tempeh

Answer 24

mold-fermented soybean

Question 25

What are the substrates used for fermentation of soybeans

Answer 25

lipids and proteins

Question 26

What does boiling do to fermentation of tempeh (3)

Answer 26

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

Question 27

formula for %TA

Answer 27

%TA =

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

times 100

Question 28

What is the molecular weight of lactic acid

Answer 28

90