Intrinsic Parameters Flashcards
1
Q
intrinsic parameters
A
aw pH Redox potential Nutrient content Vitamins Antimicrobial constituents biological structures competitive microflora
2
Q
Water activity (aw)
A
- Moisture content
- Ratio of water vapor pressure of pure water at the same temperature
3
Q
aw formula
A
P/Po
P = vapor pressure of solution
Po = vapor pressure of solvent
4
Q
Relative Humidity
A
100 x aw
5
Q
Common aw values
A
Pure water: 1.00
22% NaCl: 0.86
Fresh food: >0.99
6
Q
Min aw value for microbial growth: bacteria
A
0.90
7
Q
Min aw value for microbial growth: yeast
A
0.88
8
Q
Min aw value for microbial growth: mold
A
0.80
9
Q
Low aw:
A
Increases lag phase
Decreases growth rate
Decreases max population
10
Q
aw lowering food additives
A
NaCl
KCl
Carbs
Phosphates
11
Q
growth decreases as…
A
aw decreases
12
Q
Best microbial growth pH level:
A
6.0 - 7.5
13
Q
Few organisms grow at pH below
A
4.0
14
Q
No growth of C. botulinum at or below
A
4.6
15
Q
Butter pH
A
6.1 - 6.4
