Fermentation Flashcards
What are the two microorganisms used in fermentation way back 3000 BC, by Egyptians
Lactic Acid Bacteria and Yeast
In what century did the leavening agent changed form sourdough to baker’s yeast?
19th century
What is the scientific name of baker’s yeast
Saccharomyces cerevisiae
What is the staple dough processing method in the industry?
Straight dough method
What is the traditional leavening agent in Europe before?
Sourdough
What is the healthier option in bakery products, sourdough or baker’s yeast?
Sourdough
How can we effectively increase number of yeast cells when growing yeast in the lab?
media for inocula should have sugars, minerals, salts, vitamins with intensive aeration. and nutrient feed, pH regulation, and temp should be controlled
Which has a longer shelf life at ambient temp, dry or wet baker’s yeast?
Dry form
The wet form of bakers’ yeast is also known as cream yeast and contains how much moisture?
82%
How long can a bakers yeast in wet form last in 2-4.5C
3-4 weeks
Can instant dry yeast be mixed directly with other ingredients?
Yes. Because it already underwent a fluidized bed dryer where particle porosity increases and eliminating the step of rehydration.
What do you call the type of yeast with added antioxidants placed in a packaging designed to reduce effect of oxygen
Protected Active Dry Yeast
What are the three LAB classifications
Obligate homofermentative bacteria
Obligate heterofermentative bacteria
Facultative heterofermentative bacteria
What are the dominant Lactobacillus species in wheat flour?
La. plantarum
La. curvatus
La. paracasei
La. sanfranciscensis
La. pentosus
La. paraplantarum
La. sakei
La. brevis
La. reuteri is the dominant stable microbe in what flour sourdough?
rye flour sourdough
What are the dominant microorganisms in Amaranth flour souroughs?
La. plantarum
Pediococcus pentosaceus
What are the factors that influence the competitiveness of microoragnisms in sourdough?
type of substrate
fermentation temperature
acidity
interaction among microoragnisms
What is the main substrate for lactic acid fermentation
Glucose
By using homofermentative LAB, glucose is converted into lactic acid through glycolysis, resulting in how many ATPs?
2 molecules of ATP
What kind of fermentation can facultative heterofermntative LAB conduct?
Hexose fermnetation through glycolysis
In heterofermentation, how many ATPs are produced?
only one.
What are the other products in heterfermantation, aside from lactic acid?
Acetic acid, CO2 gas, and ethanol
What kind of fermentation results in equal production of LAB and Acetic acid but without CO2?
pentose fermentation
Can sourdough be made without yest?
yes. with or without
This type of sourdough uses microorganisms which are heat and acid tolerant
Type II
This type of sourdough includes LAB and leavening agent (bakers yeast) and uses heat tolerant microorganisms
Type III
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
Type I
true or false
max growth rate of yeast is increased due to the presence of LAB
FALSE. reduced
true or false
ethanol production of yeast is decreased in fermentation involving yeast and LAB but final yeast cell count is not afffected
TRUE.
true or false
yeast fermentation inhibits the production of mannitol and acetic acid by the LAB
false. enhances
true or false
stability of LAB population can be determined by rate and intensity of acidification
True. but acidification depends on temp, time, and water content.
what is the frequently found yeast in sourdough fermentation
Saccharomyces cerevisiae
Are temp and acidity directly proportional in a fermentation system?
yes. increasing temp increases pH
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
TRUE
What yeast species were fond to exhibit superior proofing activity more than Saccharomyces cerevisiae
Kluyveromyces marxianus
true or false
interaction between yeasts and LAB significantly affects the stability of sourdough fermentation
true
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?
True.
It is the period of proofing where the generation rate is balanced by the rate of gas leaving the dough
Stationary phase
The phase the initial yeast fermentation takes place and is when CO2 gas is produced to diffuse towards the air nuclei
Lag phase
Is it true that high temp speeds up yeast activity and decreases gas solubility?
Yes.
Exopolysaccharide develops during lactic acid fermentation resulting in the change of viscoelastic properties of dough and the bread itself. True or false
True.
true or false
glutenins are both high molecular weight and low molecular weight
TRUE
glutenins and gliadins are degraded in proteolysis. true or false
true
true or false
peptidase first catalyze protein degradation, producing proteinases which are then hydrolyzed and broken down by peptides, resulting to amino acids
FALSE.
instead of:
peptidase - proteinase
proteinases - peptides
peptides- peptidase
What is responsible for dough strength and elasticity, HMW glutenins or LMW glutenins
HMW glutenins
LMW glutenins and gliadins is responsible for dough viscous properties during the degradation of both. true or false
true
It is an alternative process to production of bakery products for people with celiac disease
proteolysis - degradation of glutenin and gliadin
homofermentative LAB produces high amount of aldehyde groups while heterofermentative LAB produces flavor compounds such as ethyl acetate and hexyl acetate. true or false
trueee
Flavor generation time can be shortened to a few hours in the presence of yeast fermentation. true or false
true
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
true
what b-vitamins are increased during long periods of yeast fermentation
thiamin and riboflavin
some vitamins E are loss during what fermentation
sourdough
spoilage fungi spoil yeast leavening products but it can be prevented naturally by addition of sourdough. true or false
true
heterofermentative fermentation produces lactic acid and acetic acid which are good antifungal compounds. true or false
true
it is the heterofermentative LAB specie claimed to have the most effective antifungal activity
La. sanfranciscensis
It is the heterofermentative LAB that is the most widely used strain in sourdough and gives long-term effective antifungal activity
La. plantarum
which do industrial bakers prefer, fermentations using starters or natural fermentation
using starters, for higher numbers of microorganisms and less variation of microbial counts, easier to control and hence consistency of fermentation process
What are the products of heterofermentative LAB
lactic acid (decrease pH)
acetic acid (antifungal agent)
exopolysaccharides (gut health promoter)
volatile compounds (flavoring agent)
What is the purpose of amino acids, why should they be obtained from proteolysis
they promote yeast growth and enable the development of Maillard flavor compounds
