Food Fermentation 1

Question 1

What is fermentation in LAB?

Answer 1

fermenting CHO to LA (change in ph) decreases.

Question 2

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

Answer 2

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

Question 3

What are the conditions that LAB will grow in?

Answer 3

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.

Question 4

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

Answer 4

YEAST!

Question 5

What are the two groups of LAB?

Answer 5

Homo-fermentative and heterofermentative.

Question 6

What is homo-fermentative?

Answer 6

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

Question 7

What is hetero-fermentative?

Answer 7

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

Question 8

What causes slime?

Answer 8

dextran from sucrose

Question 9

What amines can be produced by LAB?

Answer 9

Tyramine, histamine

Question 10

Tell me about Streptococcus thermophilus

Answer 10

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

Question 11

What are three things about Lactobacilli?

Answer 11

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

Question 12

Obligate homofermentative lactobacilli

Answer 12

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

Question 13

Faculative heterofermative

Answer 13

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.

Question 14

Obilgate heterofermative

Answer 14

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.

Question 15

What lactobacillus is used in swiss cheese?

Answer 15

Lactobacillus helveticus

Question 16

What lactobacillus is used in yogurt??

Answer 16

delbrueckii

Question 17

Why doe you need two colonies to make yogurt

Answer 17

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

Question 18

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

Answer 18

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

Question 19

What are some examples of heterofermenatative?

Answer 19

Leuconostoc

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

Question 20

Propionibacterium shermanii.. a little about this bacteria..

Answer 20

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

Question 21

What are other organisms used in fermentation?

Answer 21

FUNGI Penicillium spp. geotrichum candidum.

Question 22

What else in food fermentation?

Answer 22

Protein and fat degratdation (increase pH) RISK

Question 23

4 things for a starter culture

Answer 23

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

Question 24

1. Rapid fermentation of lactose

Answer 24

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

Question 25

Proteinase activity

Answer 25

Break down proein for energy. PRT-

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

Question 26

Phage resistant

Answer 26

Inactive phase!

block RNA/DNA injection,

Question 27

Production of inhibitory sustances

Answer 27

bacteriocins- slows down growth

organic acids