C8 Fermented milk products Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Describe the effects conferred to yoghurt by microorganisms.

A
  • Soft gel texture: Lactic acid lowers pH to isoelectric point of casein (Casein-casein interaction) and cause coagulation, forming a continuous gel. Exopolysaccharides also increase retention of water and lower whey separation, increasing viscosity, creaminess and smoothness
  • Unique aroma and flavor compounds: production of acetaldehyde, diacetyl, free amino acids and unsaturated fatty acids.
  • Antimicrobial properties from acid and bacteriocins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the symbiotic relationship between yoghurt cultures.

A

S. thermophilus:
- Produces formic and folic acid, which helps purine biosynthesis in L. bulgaricus
- Produce CO2 and consume O2, benefits the less aerotolerant L. bulgaricus
- Exopolysaccharides ensure close proximities, facilitating exchange of metabolites
- Glutathione relieve acid stress in L. bulgaricus

L. bulgaricus
- Increase oligopeptides that support S. thermophilus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the factors affecting the fermentation of yoghurt.

A
  • Composition of starter culture (St & Lb ratio = 1:1)
  • Incubation temperature (40-43C)
  • Fat content of milk (More fat = More viscous and higher incubation time)
  • Amount of inoculum used (Higher inoculum = increased rate of fermentation)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does amount of inoculum affect yoghurt fermentation?

A
  • Reduce lag phase of bacteria in the starter culture
  • Increase rate of acid production
  • Faster fermentation
  • Prevents pathogen or spoilage microbes from growing/surviving
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two important indicators of successful yoghurt fermentation?

A

pH: 4-4.6
Amount of live cultures >= 10^6 CFU/ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly