INTRODUCTION TO FOOD TECHNOLOGY
FOOD SCIENCE VS FOOD TECHNOLOGY
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
measured from 1 to 3
|
|
|
the measure of vapor pressure over pure water
|
|
|
the water available to support enzyme activity
|
|
|
all of the above
|
Detailed explanation-1: -Water activity is an index which indicates how much water is accessible to the enzyme. Polar solvents can ad-sorb more water, while in non-polar solvents less water is required to achieve saturation and form a new aqueous phase where the water activity of the organic solvent is equal to one (aw = 1).
Detailed explanation-2: -The effect of water activity (a(w)) on V(max) showed that the enzyme activity in general increased with increasing amounts of water for the three enzymes. This was shown both for esterification and hydrolysis reactions catalyzed by R.
Detailed explanation-3: -Water activity is defined as the ratio of the vapor pressure of water in a material (p) to the vapor pressure of pure water (po) at the same temperature. Relative humidity of air is defined as the ratio of the vapor pressure of air to its saturation vapor pressure.
Detailed explanation-4: -2. At low water activity, the reduced hydration produces conformational changes in the enzyme, affecting its catalytic activity. The relationship between water content and water activity is complex. An increase in aw is usually accompanied by an increase in water content, but in a non-linear fashion.