Micro - Final: Food Fermentations

Front 1

What is the major difference between a food that spoils and one that ferments?

Back 1

It's enviroment: most fermentations are anaerobic. Salt is another factor.

Front 2

Why do fish spoil readily?

Back 2

There is little to no glycogen sores: nothing for microbes to much on and drop pH

Front 3

Name a fermentation
Veg/Fruit
Meat/Fish
Beverage
Legume
Cereal
Milk
Starch

Back 3

Sauerkraut, wine, pickle, olive
Salami, pepperoni
Alcohol, tea, coffee, cocoa
Tempeh, soy sause
Bread (sour dough), pozol
Yogurt, cheese
Vodka, gari (cassava)

Front 4

Why are food fermented?

Back 4

Preservation
Taste, nutrition
Toxicity
Decrease cook time

Front 5

What are the coenzymes of metabolism?

Back 5

NAD & FAD
These must be regenerated. HOW they're regenerated aerobic/anaerobic is different.

Front 6

How is NAD regenerated both in the presence of O2 and anaerobic?

Back 6

If O2: chemiosmotic cycle (e-transport chain)
If not O2: fermentation

Front 7

What compound do sugars get broken down into initially?

Back 7

Pyruvate

Front 8

In aerobic, what happens to puruvate?

Back 8

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

Front 9

In anaerobic, what happens to pyruvate?

Back 9

Somehow reacts to regenerate NADH. Ie in homolactic: 2 pyruvates react to make lactate, CO2, and regen. NAD

Front 10

What is the ethanol fermentation pathway?

Back 10

Pyruvate-->acetaldehyde-->ethanol
CO2 produced in 1st step
NAD reg. in 2nd step

Front 11

Heterolactic ferm. products?

Back 11

Alchohol + homo:
ethanol, lactate, CO2

Front 12

Proprionic ferm. products?

Back 12

Proprionate, CO2, acetic acid
(swiss cheese!)

Front 13

Name important fermenters of:
Yeast
Mold
Bacteria

Back 13

Saccharomyces cerevisiae
Rhizopus, penicillium, fusarium
Many
Lactococcus lactis
Lactobacillus (plant. & bulgaricus)
Strep. Thermophilus
Leuconostoc

Front 14

What are the main flavor components of Sauerkraut?

Back 14

Diacetyl, lactic acid, mannitol

Front 15

What conditions are needed for proper sauerkraut fermentation?

Back 15

Anaerobic
Salt! 2.25-3%
Proper organisms

Front 16

What are the most important bacteria of sauerkraut fermentation?

Back 16

1. leuconostoc mesenteroides
2. lactobacillus plantarium

#1 kicks it off, drops pH. #2 takes over.

Front 17

How long does sauerkraut ferment? Final pH?

Back 17

3-4 weeks, pH ~3.5

Front 18

If my sauerkraut is ___ what went wrong?
Dark
Pink
Off flavors

Back 18

Dark - High T, High O2, too much salt
Pink - yeast
Off - wrong dominant bacteria

Front 19

What is the main difference w/Kimchi/sauerkraut?

Back 19

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)

Front 20

Pickle fermentation : what is process?

What are microbes?

Back 20

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

Front 21

What are the important microbes in pickle fermentation?

Back 21

Pediococcus Cerevisiae -early
Lactococcus Brevis - early
Lactobacillus Plantarium - later

Front 22

Pickles... what could go wrong?

Back 22

Bloaters! if heterofermenters present & CO2 produced
Pectinases: loss of tecture - problem w/recycled brine
Off flavors/color

Front 23

Olive fermentation; what is process?

Back 23

1. ALKALI TREATMENT!!! Reduce bitter compounds; then wash
2. Brine 16-20ºS
3. Ferment
4. Olive Oil added to top

Front 24

What is the alkali treatment. Why?

Back 24

.9-1.25% NaOH - hydrolizes Oleuropin

Front 25

Why is olive oil added to top of container?

Back 25

Aesthetics and to prevent yeast growth

Front 26

Fish eyes on olives are caused by what? What is another main problem of olive fermentation?

Back 26

Coliforms.
Loss of texture.

Front 27

What is the main bug in wine production?

Back 27

Yeast: Saccharomyces cerevisiae

Front 28

Why is sulfur dioxide used?

Back 28

Antimicrobial
antioxidant
bust open grape cells

Front 29

Main steps in wine

Back 29

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

Front 30

What is the secondary wine fermentation?

Back 30

Conversion of Malic acid into lactate (decarbox.)/ done in oak barrels
by
Oenococcus oenus

Front 31

Name a mold used in wine production

Back 31

Botritus Cinera
Sweet wine

Front 32

What is the 1st step of beer making?

Back 32

1. Malting: grain is soaked allowed to sprout. Enzymes including amylase produces.

Front 33

Next two steps?

Back 33

Kilning/Brewing
-malt dried
-rehydrated and cooked, sometimes with adjunct starch/enzymes. Release of sugars from starch. "WORT" Hops added at this stage.

Front 34

Wort ready, now what? What T?

Back 34

Yeast added, and beer is fermented. T depends on brew type.

Front 35

What is Whiskey?

Back 35

Distilled beer
Single or mixed malt, wood aged

Front 36

Brandy?

Back 36

Distilled wine, wood ages

Front 37

Vodka

Back 37

Fermented Potatoes usually; multiple distillations

Front 38

Name a bacteria used to make alcohol.

Back 38

Tequila!
Zymomonus Mobilis
Fermentation of cactus
2x distilled

Front 39

Port? Sherry? Madeira?

Back 39

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

Front 40

Vinegar - how produced?

Back 40

From apples, rice, grapes, grain
Two stage:
1. --> alchohol (yeast)
2. --> acetic acid (acetobacter) (aerobic! often done by dripping wine onto wood chips)

Front 41

What is balsamic vinegar made from?

Back 41

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.

Front 42

Dairy: Name some NON LAB bacteria
(FULL NAMES!)

Back 42

Propionibacterium shermanni (swiss)
Brevibacterium linens (limburg)

Front 43

Name some molds used in dairy

Back 43

penicillium camembert
penicillium roqueforti

Front 44

LAB used in Dairy
- mesophiles
- thermophiles

Back 44

Meso: lactococcus lactic susp. lactis (&biovar diacetyl) & susp. cremoris

Thermo: streptococcus thermophilus, lactobacillus bulgaricus

Front 45

Why are LAB so successful in dairy (general)?

Back 45

1. Ability to digest Lactose
2. Proteolytic system
3. phage resistant
4. bacteriocin production
5. citrate metabolism

***NOTE** THESE ARE ENCODED ON PLASMIDS!!!!

Front 46

Explain the lactose digestion

Back 46

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

Front 47

Explain the proteolytic system

Back 47

Extracellular proteases (PrtP)
Peptide transport system
peptidases to utilize peptides

Front 48

How is cheese produced? (Two MAIN steps)

Back 48

1. Drop pH w/LAB
2. Chymosin cleavage of k-casein

Front 49

What is the main workhorse of cheese?

Back 49

Lactococcus lactis

Front 50

What happens during the aging of cheddar?

Back 50

Proteolytic bacteria cleave proteins; make peptides which increase flavor (S. thermophilus)

Front 51

Swiss cheese bacteria (TWO)?

What are end products?

Back 51

S. thermophilus and Proprionibacterium shermanii --> makes CO2 and propionic acid and glutamic acid

Front 52

Blue cheese

Back 52

Lact. lactis, and then injected with penicillium roqueforti

Front 53

What are the stages of phage infection?

Back 53

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

Front 54

How do LAB responds?

Back 54

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

Front 55

What is interesting about the Defense mechanisms?

Back 55

They're (like the LAB's ability to survive) are encoded on plasmids.

Front 56

What are main bugs that make yogurt?

Back 56

1. Streptococcus thermophilus
2. Lactobacillus bulgaricus

Front 57

What temp is yogurt fermented/ how long?

Back 57

45ºC - these are thermophiles; fermented until pH ~4.6: then "break"

Front 58

What is the main flavor component of yogurt?

Back 58

acetaldehyde

Front 59

How do the two buggers work together?

Back 59

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)