EXERCISE 9 Flashcards
Food preservation technology mediated by microorganisms
Fermentation
Metabolic process of deriving energy from organic compounds without oxidizing agent
Fermentation
Factors affecting fermentation (6)
Substrate
Solute Concentration
pH
Temperature
Aeration
Fermenting microorganism
How to ferment vegetables
dry-salting or brining
What are the reactants and products of fermentation
sugars and lactic acid
Significance of Salting (4)
- 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
Why is boiled rice water added to mustasa
adds dissolves carbohydrates which helps convert to lactic acid bacteria
Why is mustasa put into a jar with plastic cover?
prevent oxygen which may reduce redox potentials + physical exclusion
3 factors that favours growth of LAB
- addition of salt
- production of lactic acid lowers pH, inhibiting growth of other organisms
- produces CO2 which contributes to anaerobic environment
When does growth of initial bacteria slow down or stop?
upon accumulation of acid, giving rise to LAB
What is the medium of Lactic Acid Bacteria
de Man Rogosa and Sharpe Agar (MRSA AGAR)
what is present in MRSA that inhibit growth of other organisms EXCEPT for LAB (2)
sodium acetate and ammonium citrate
Color of LAB colonies
creamy to off white
What does the presence of coliforms denote?
indicates presence of pathogenic microorganisms
What is the medium of Coliforms
Violet Red Bile Agar
VRBA
- inhibitory components (2)
- indicator system (2)
crystal violet and bile salts
lactose and neutral red
Color of Coliform colonies
pink to red
during fermentation, acid development is carefully monitored until what pH level
4.1
What microorganisms do VRBA inhibit the growth of
Gram +
What microorganism is responsible for fermentation in tempeh?
Rhizopus microsporus var. oligosporus
How much acetic acid does vinegar contain?
4%
Where is vinegar produced from?
acetous fermentation of ethanol
What is the ph of vinegar
2.0 - 3.5
2 distinct processes that result to VINEGAR
- ethanolic fermentation by yeasts
- production of acetic acid from ethanol by acetic acid bacteria
What is tempeh
mold-fermented soybean
What are the substrates used for fermentation of soybeans
lipids and proteins
What does boiling do to fermentation of tempeh (3)
- enhances extraction of soluble nutrients
- inactivates microorganisms that might interfere with fermentation
- denatures trypsin inhibitor (anti-nutritional factor soy protein)
formula for %TA
%TA =
[(volume of titrant)(N of titrant)(molecular weight of lactic acid/1000)]
- - - – - – - - - - -
(volume of sample of barong mustasa)
times 100
What is the molecular weight of lactic acid
90
Vinegar total composition (5)
- alcohol
- glycerin
- esters
- sugars
- salts
a fermentation technique that involves adding a small amount of a previous ferment to a new one
Backslop
2 ways to prepare YEAST STARTER CULTURE
- increase # of yeast cells
- shaking - aeration
EFFECT of addition of sugar in Alcoholic fermentation
- increase concentration of fermentable hexoses in coconut water
4 stages in Alcoholic fermentaion
- addition of sugar
- starter culture
- conversion of sugars to ethanol
- bung set-up
STAGES IN ALCOHOLIC FERMENTION
what happens in STARTER CULTURE
- yeast strains is selected
- inoculated into juice
How is fermentation monitored in BUNG SET UP
formation of bubbles
In bung set up, is O2 levels limited to be exposed against fermenting liquid
yes
What types of organisms perform acetic acid fermentation?
obligate aerobes
In acetic acid fermentation, fermentation is initiated by either (2)
pure culture o r backslopping
What happens in acetic acid fermetnation
ethanol is oxidized back to acetaldehyde; acetaldehyde is further oxidized to acetic acid
how to prepare TEMPEH FERMENTAITON (3)
- R. oligosporus spore suspension is added directly to the beans
- using dried tempeh culture that serves as backslop material
- use of “usar” which is made by inoculating wild Rhizopus spores onto surface of
Hibiscus plant
statutory limits for total coliform count in water
< 1.1 mpn/mL
