Fermentation

Question 1

What are the two microorganisms used in fermentation way back 3000 BC, by Egyptians

Answer 1

Lactic Acid Bacteria and Yeast

Question 2

In what century did the leavening agent changed form sourdough to baker’s yeast?

Answer 2

19th century

Question 3

What is the scientific name of baker’s yeast

Answer 3

Saccharomyces cerevisiae

Question 4

What is the staple dough processing method in the industry?

Answer 4

Straight dough method

Question 5

What is the traditional leavening agent in Europe before?

Answer 5

Sourdough

Question 6

What is the healthier option in bakery products, sourdough or baker’s yeast?

Answer 6

Sourdough

Question 7

How can we effectively increase number of yeast cells when growing yeast in the lab?

Answer 7

media for inocula should have sugars, minerals, salts, vitamins with intensive aeration. and nutrient feed, pH regulation, and temp should be controlled

Question 8

Which has a longer shelf life at ambient temp, dry or wet baker’s yeast?

Answer 8

Dry form

Question 9

The wet form of bakers’ yeast is also known as cream yeast and contains how much moisture?

Answer 9

82%

Question 10

How long can a bakers yeast in wet form last in 2-4.5C

Answer 10

3-4 weeks

Question 11

Can instant dry yeast be mixed directly with other ingredients?

Answer 11

Yes. Because it already underwent a fluidized bed dryer where particle porosity increases and eliminating the step of rehydration.

Question 12

What do you call the type of yeast with added antioxidants placed in a packaging designed to reduce effect of oxygen

Answer 12

Protected Active Dry Yeast

Question 13

What are the three LAB classifications

Answer 13

Obligate homofermentative bacteria
Obligate heterofermentative bacteria
Facultative heterofermentative bacteria

Question 14

What are the dominant Lactobacillus species in wheat flour?

Answer 14

La. plantarum
La. curvatus
La. paracasei
La. sanfranciscensis
La. pentosus
La. paraplantarum
La. sakei
La. brevis

Question 15

La. reuteri is the dominant stable microbe in what flour sourdough?

Answer 15

rye flour sourdough

Question 16

What are the dominant microorganisms in Amaranth flour souroughs?

Answer 16

La. plantarum
Pediococcus pentosaceus

Question 17

What are the factors that influence the competitiveness of microoragnisms in sourdough?

Answer 17

type of substrate
fermentation temperature
acidity
interaction among microoragnisms

Question 18

What is the main substrate for lactic acid fermentation

Answer 18

Glucose

Question 19

By using homofermentative LAB, glucose is converted into lactic acid through glycolysis, resulting in how many ATPs?

Answer 19

2 molecules of ATP

Question 20

What kind of fermentation can facultative heterofermntative LAB conduct?

Answer 20

Hexose fermnetation through glycolysis

Question 21

In heterofermentation, how many ATPs are produced?

Answer 21

only one.

Question 22

What are the other products in heterfermantation, aside from lactic acid?

Answer 22

Acetic acid, CO2 gas, and ethanol

Question 23

What kind of fermentation results in equal production of LAB and Acetic acid but without CO2?

Answer 23

pentose fermentation

Question 24

Can sourdough be made without yest?

Answer 24

yes. with or without

Question 25

This type of sourdough uses microorganisms which are heat and acid tolerant

Answer 25

Type II

Question 26

This type of sourdough includes LAB and leavening agent (bakers yeast) and uses heat tolerant microorganisms

Answer 26

Type III

Question 27

What type of sourdough is incubated ta low temp (<30 C) and is subjected to continuous back-slopping using the mother sponge from prev fermentation in order to keep activity of microbes at high rate

Answer 27

Type I

Question 28

true or false max growth rate of yeast is increased due to the presence of LAB

Answer 28

FALSE. reduced

Question 29

true or false ethanol production of yeast is decreased in fermentation involving yeast and LAB but final yeast cell count is not afffected

Answer 29

TRUE.

Question 30

true or false yeast fermentation inhibits the production of mannitol and acetic acid by the LAB

Answer 30

false. enhances

Question 31

true or false stability of LAB population can be determined by rate and intensity of acidification

Answer 31

True. but acidification depends on temp, time, and water content.

Question 32

what is the frequently found yeast in sourdough fermentation

Answer 32

Saccharomyces cerevisiae

Question 33

Are temp and acidity directly proportional in a fermentation system?

Answer 33

yes. increasing temp increases pH

Question 34

true or false to ensure high degree of acidification and flour development, microbes should be selected from their transition and stationary phases for sourdough making

Answer 34

TRUE

Question 35

What yeast species were fond to exhibit superior proofing activity more than Saccharomyces cerevisiae

Answer 35

Kluyveromyces marxianus

Question 36

true or false interaction between yeasts and LAB significantly affects the stability of sourdough fermentation

Answer 36

true

Question 37

In the mechanisms during fermentation, is it true that the generation rate of CO2 is related to the number of yeast cells and rate of metabolism of yeast?

Answer 37

True.

Question 38

It is the period of proofing where the generation rate is balanced by the rate of gas leaving the dough

Answer 38

Stationary phase

Question 39

The phase the initial yeast fermentation takes place and is when CO2 gas is produced to diffuse towards the air nuclei

Answer 39

Lag phase

Question 40

Is it true that high temp speeds up yeast activity and decreases gas solubility?

Answer 40

Yes.

Question 41

Exopolysaccharide develops during lactic acid fermentation resulting in the change of viscoelastic properties of dough and the bread itself. True or false

Answer 41

True.

Question 42

true or false glutenins are both high molecular weight and low molecular weight

Answer 42

TRUE

Question 43

glutenins and gliadins are degraded in proteolysis. true or false

Answer 43

true

Question 44

true or false peptidase first catalyze protein degradation, producing proteinases which are then hydrolyzed and broken down by peptides, resulting to amino acids

Answer 44

FALSE. instead of: peptidase - proteinase proteinases - peptides peptides- peptidase

Question 45

What is responsible for dough strength and elasticity, HMW glutenins or LMW glutenins

Answer 45

HMW glutenins

Question 46

LMW glutenins and gliadins is responsible for dough viscous properties during the degradation of both. true or false

Answer 46

true

Question 47

It is an alternative process to production of bakery products for people with celiac disease

Answer 47

proteolysis - degradation of glutenin and gliadin

Question 48

homofermentative LAB produces high amount of aldehyde groups while heterofermentative LAB produces flavor compounds such as ethyl acetate and hexyl acetate. true or false

Answer 48

trueee

Question 49

Flavor generation time can be shortened to a few hours in the presence of yeast fermentation. true or false

Answer 49

true

Question 50

volatile compounds reduced quickly in the presence of yeast leavening while general flavor can be maintained for a longer period with addition of sourdough. true or false

Answer 50

true

Question 51

what b-vitamins are increased during long periods of yeast fermentation

Answer 51

thiamin and riboflavin

Question 52

some vitamins E are loss during what fermentation

Answer 52

sourdough

Question 53

spoilage fungi spoil yeast leavening products but it can be prevented naturally by addition of sourdough. true or false

Answer 53

true

Question 54

heterofermentative fermentation produces lactic acid and acetic acid which are good antifungal compounds. true or false

Answer 54

true

Question 55

it is the heterofermentative LAB specie claimed to have the most effective antifungal activity

Answer 55

La. sanfranciscensis

Question 56

It is the heterofermentative LAB that is the most widely used strain in sourdough and gives long-term effective antifungal activity

Answer 56

La. plantarum

Question 57

which do industrial bakers prefer, fermentations using starters or natural fermentation

Answer 57

using starters, for higher numbers of microorganisms and less variation of microbial counts, easier to control and hence consistency of fermentation process

Question 58

What are the products of heterofermentative LAB

Answer 58

lactic acid (decrease pH) acetic acid (antifungal agent) exopolysaccharides (gut health promoter) volatile compounds (flavoring agent)

Question 59

What is the purpose of amino acids, why should they be obtained from proteolysis

Answer 59

they promote yeast growth and enable the development of Maillard flavor compounds