Food Fermentation 1 Flashcards

1
Q

What is fermentation in LAB?

A

fermenting CHO to LA (change in ph) decreases.

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2
Q

What are LAB? gram + or gram -? spores? gaseous environement?

A

LAB are gram + with nonsporulating, nonmotile. with low DNA content.
- anaerobic meats

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3
Q

What are the conditions that LAB will grow in?

A
approperiate ph (low) and CHO preesnt. 
fermented foods such as: dairy, wine, sourdouhs, and spoilage foods such as off odors from H2S and off flavors from organic acid.
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4
Q

What is one thing LAB has to compete with during fermenation in beer?

A

YEAST!

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5
Q

What are the two groups of LAB?

A

Homo-fermentative and heterofermentative.

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6
Q

What is homo-fermentative?

A

Use ONLY 6C sugars. Produces NO gas, and ends with lactic acid.

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7
Q

What is hetero-fermentative?

A

Ends in Lactic acid, acetic acid, and CO2 given off as well as ethanol. Can use 5C
- NO CO2 given off if using 5C.
ONLY CO2 if

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8
Q

What causes slime?

A

dextran from sucrose

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9
Q

What amines can be produced by LAB?

A

Tyramine, histamine

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10
Q

Tell me about Streptococcus thermophilus

A

Thermophile grows at 45-50C NOT found in fridge. Limited proteolytic activity.

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11
Q

What are three things about Lactobacilli?

A
  1. fastidious.
  2. Can be aciduric or acidophilic
  3. Rarely pathogenic
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12
Q

Obligate homofermentative lactobacilli

A
glucose--> Lactic acid. 
Acidophilus. 
does NOT use 5C. 
NO CO2. 
2 ATP produced.
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13
Q

Faculative heterofermative

A
Can use 5C as well as 6C
Glucose--> LA (no gas)
Pentose--> LA or acetic acid
1 or 2 ATP (2ATP if go to acetic acid)
2 NADPH produced.
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14
Q

Obilgate heterofermative

A

Must use C6
- CO2!!!!
1 or 2 ATP produced depends if create acetic acid then 2. If go to ethanol 2 NAD is proced and 1 ATP.

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15
Q

What lactobacillus is used in swiss cheese?

A

Lactobacillus helveticus

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16
Q

What lactobacillus is used in yogurt??

A

delbrueckii

17
Q

Why doe you need two colonies to make yogurt

A
  1. Lactobaacillus delbueckii subsp. bulgaricus
    - Has strong proteolytic activity (provides AA)
  2. Streptococcus thermophilus
    - produces flavor
    diacetyl Butter flavor
    acetaaldehyde green apple flavor.
    acetic acid vinager
18
Q

Citrate fermentation pathway in LAB has 5 products and three flavors….what are they?

A
  1. Acetic acid- vinager
  2. acetylaldehyde- green apple
  3. diacetyl- butter
  4. acetoin
  5. 2,3-butylene glycerol no flavor
19
Q

What are some examples of heterofermenatative?

A

Leuconostoc

  • Key in veggie fermenation with Less than 5% NaCl.
  • grows in refrigirator, vacuum packed foods.
20
Q

Propionibacterium shermanii.. a little about this bacteria..

A

anaerobic LA produces CO2 and acetic aicd. nutty flavor and swiss cheese.

21
Q

What are other organisms used in fermentation?

A

FUNGI Penicillium spp. geotrichum candidum.

22
Q

What else in food fermentation?

A

Protein and fat degratdation (increase pH) RISK

23
Q

4 things for a starter culture

A
  1. rapid fermentation of lactose
  2. Proteinase activity
  3. Production of inhibotory compounds
  4. Phage resistance
24
Q
  1. Rapid fermentation of lactose
A

Use PEP/PTS to uptake the CHO into the cell and now need something ot break lactose into glucose and lactose.

25
Q

Proteinase activity

A

Break down proein for energy. PRT-

Can use other organisms such as L. delbruekii subsp. bulgaricus

26
Q

Phage resistant

A

Inactive phase!

block RNA/DNA injection,

27
Q

Production of inhibitory sustances

A

bacteriocins- slows down growth

organic acids