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59 Cards in this Set

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What is the major difference between a food that spoils and one that ferments?
It's enviroment: most fermentations are anaerobic. Salt is another factor.
Why do fish spoil readily?
There is little to no glycogen sores: nothing for microbes to much on and drop pH
Name a fermentation
Veg/Fruit
Meat/Fish
Beverage
Legume
Cereal
Milk
Starch
Sauerkraut, wine, pickle, olive
Salami, pepperoni
Alcohol, tea, coffee, cocoa
Tempeh, soy sause
Bread (sour dough), pozol
Yogurt, cheese
Vodka, gari (cassava)
Why are food fermented?
Preservation
Taste, nutrition
Toxicity
Decrease cook time
What are the coenzymes of metabolism?
NAD & FAD
These must be regenerated. HOW they're regenerated aerobic/anaerobic is different.
How is NAD regenerated both in the presence of O2 and anaerobic?
If O2: chemiosmotic cycle (e-transport chain)
If not O2: fermentation
What compound do sugars get broken down into initially?
Pyruvate
In aerobic, what happens to puruvate?
Enters TCA cycle: products = CO2 and NADH+H then onto etransport chain - cytochromes move e's (w/CoQ); H's outside cell eventually come back in
In anaerobic, what happens to pyruvate?
Somehow reacts to regenerate NADH. Ie in homolactic: 2 pyruvates react to make lactate, CO2, and regen. NAD
What is the ethanol fermentation pathway?
Pyruvate-->acetaldehyde-->ethanol
CO2 produced in 1st step
NAD reg. in 2nd step
Heterolactic ferm. products?
Alchohol + homo:
ethanol, lactate, CO2
Proprionic ferm. products?
Proprionate, CO2, acetic acid
(swiss cheese!)
Name important fermenters of:
Yeast
Mold
Bacteria
Saccharomyces cerevisiae
Rhizopus, penicillium, fusarium
Many
Lactococcus lactis
Lactobacillus (plant. & bulgaricus)
Strep. Thermophilus
Leuconostoc
What are the main flavor components of Sauerkraut?
Diacetyl, lactic acid, mannitol
What conditions are needed for proper sauerkraut fermentation?
Anaerobic
Salt! 2.25-3%
Proper organisms
What are the most important bacteria of sauerkraut fermentation?
1. leuconostoc mesenteroides
2. lactobacillus plantarium

#1 kicks it off, drops pH. #2 takes over.
How long does sauerkraut ferment? Final pH?
3-4 weeks, pH ~3.5
If my sauerkraut is ___ what went wrong?
Dark
Pink
Off flavors
Dark - High T, High O2, too much salt
Pink - yeast
Off - wrong dominant bacteria
What is the main difference w/Kimchi/sauerkraut?
Kimchi ferment stopped at about pH 4.5. The T is dropped to stop fermentation.

ALSO!! Typically higher salt concentration (l. plantarium kicks in earlier)
Pickle fermentation : what is process?

What are microbes?
1. Brine in 20-30ºS (measured by salomenter; 1ºS ~0.26%NaCl)
2. Fermenting
a. LAB + coliforms (in nat)
b. LAB + yeast (natural)
3. Post (ph @ 3.5): purge w/N2 to get O2 out
What are the important microbes in pickle fermentation?
Pediococcus Cerevisiae -early
Lactococcus Brevis - early
Lactobacillus Plantarium - later
Pickles... what could go wrong?
Bloaters! if heterofermenters present & CO2 produced
Pectinases: loss of tecture - problem w/recycled brine
Off flavors/color
Olive fermentation; what is process?
1. ALKALI TREATMENT!!! Reduce bitter compounds; then wash
2. Brine 16-20ºS
3. Ferment
4. Olive Oil added to top
What is the alkali treatment. Why?
.9-1.25% NaOH - hydrolizes Oleuropin
Why is olive oil added to top of container?
Aesthetics and to prevent yeast growth
Fish eyes on olives are caused by what? What is another main problem of olive fermentation?
Coliforms.
Loss of texture.
What is the main bug in wine production?
Yeast: Saccharomyces cerevisiae
Why is sulfur dioxide used?
Antimicrobial
antioxidant
bust open grape cells
Main steps in wine
1. crush (get "must")
2. ferment -- and press at some point (pomace is left over)
3. Racking (siphoning off) - timing key don't want lysed yeast cells
4. Aging
What is the secondary wine fermentation?
Conversion of Malic acid into lactate (decarbox.)/ done in oak barrels
by
Oenococcus oenus
Name a mold used in wine production
Botritus Cinera
Sweet wine
What is the 1st step of beer making?
1. Malting: grain is soaked allowed to sprout. Enzymes including amylase produces.
Next two steps?
Kilning/Brewing
-malt dried
-rehydrated and cooked, sometimes with adjunct starch/enzymes. Release of sugars from starch. "WORT" Hops added at this stage.
Wort ready, now what? What T?
Yeast added, and beer is fermented. T depends on brew type.
What is Whiskey?
Distilled beer
Single or mixed malt, wood aged
Brandy?
Distilled wine, wood ages
Vodka
Fermented Potatoes usually; multiple distillations
Name a bacteria used to make alcohol.
Tequila!
Zymomonus Mobilis
Fermentation of cactus
2x distilled
Port? Sherry? Madeira?
Both are wines w/early stop to ferment (added to Brandy/ alcohol kills yeast). Port: added + aged. Sherry: solera system

Madeira same as Port but has 40-50ºC aging for few months
Vinegar - how produced?
From apples, rice, grapes, grain
Two stage:
1. --> alchohol (yeast)
2. --> acetic acid (acetobacter) (aerobic! often done by dripping wine onto wood chips)
What is balsamic vinegar made from?
Trebianno grapes. Cooked to reduce must; added to barrel. Transfered 1x every year into new (and different wood) barrel. Aeration causes some alcohol conversion to acetic acid.
Dairy: Name some NON LAB bacteria
(FULL NAMES!)
Propionibacterium shermanni (swiss)
Brevibacterium linens (limburg)
Name some molds used in dairy
penicillium camembert
penicillium roqueforti
LAB used in Dairy
- mesophiles
- thermophiles
Meso: lactococcus lactic susp. lactis (&biovar diacetyl) & susp. cremoris

Thermo: streptococcus thermophilus, lactobacillus bulgaricus
Why are LAB so successful in dairy (general)?
1. Ability to digest Lactose
2. Proteolytic system
3. phage resistant
4. bacteriocin production
5. citrate metabolism

***NOTE** THESE ARE ENCODED ON PLASMIDS!!!!
Explain the lactose digestion
PTS: phosphotransferase system. LAB are able to uptake lactose and phosphorylate it so it says inside

phospho-beta-galactosidase: has enzymes to digest phosphor. lactose
Explain the proteolytic system
Extracellular proteases (PrtP)
Peptide transport system
peptidases to utilize peptides
How is cheese produced? (Two MAIN steps)
1. Drop pH w/LAB
2. Chymosin cleavage of k-casein
What is the main workhorse of cheese?
Lactococcus lactis
What happens during the aging of cheddar?
Proteolytic bacteria cleave proteins; make peptides which increase flavor (S. thermophilus)
Swiss cheese bacteria (TWO)?

What are end products?
S. thermophilus and Proprionibacterium shermanii --> makes CO2 and propionic acid and glutamic acid
Blue cheese
Lact. lactis, and then injected with penicillium roqueforti
What are the stages of phage infection?
1. attachment of phage to receptor
2. Injection of DNA
3. Utilization of enzymed for replication
4. Transcription of genes: production of phage "parts"
5. Assembly of parts
6. Production of enzymes that can break cell wall
How do LAB responds?
Defense!! Defense!!

1. Exo-polysaccharide coating to mask cell (prevent attachment)
2. block injection
3. Restriction modification: chop up DNA
4. Abortive infection - prevent duplication or some later step
What is interesting about the Defense mechanisms?
They're (like the LAB's ability to survive) are encoded on plasmids.
What are main bugs that make yogurt?
1. Streptococcus thermophilus
2. Lactobacillus bulgaricus
What temp is yogurt fermented/ how long?
45ºC - these are thermophiles; fermented until pH ~4.6: then "break"
What is the main flavor component of yogurt?
acetaldehyde
How do the two buggers work together?
They're synergistic: S. thermo drops pH, kickstarts l. bulgaricus. Together they make more acetaldehyde than if they were alone. if l. bulgaricus alone, it would take forever to get it started ( it likes to eat peptides & S. thermo makes peptides)