Product Preservation 3

Question 1

In order to test preservative efficacy, what factors must be standardise?

Answer 1

• Origin (strains, species), inoculum concentration and physiological state of test organism
• Composition of pH of culture medium
• Exposure and incubation times (temperature, time)

Question 2

Different strains of a same species may exhibit slight variations in their properties. How can we obtain control strains? Give example.

Answer 2

Culture collections e.g. JCM, ATCC, CBS

Question 3

High inoculum levels of the test organism tend to result in ________ activity of the antimicrobial chemicals. This can occur due to:

Answer 3

reduced

• Drug adsorption on to the cell surface and absorption into the interior of the cell.
• Some organism can synthesize inactivating enzymes

Question 4

How does pH affect preservative efficacy?

Answer 4

Many preservatives are weak acids or bases, which are more lipid soluble in ionised form. The pH affects the degree of ionisation, hence their lipid solubility and so, their antimicrobial effect.

Question 5

How else can composition of culture medium affect efficacy of preservative?

Answer 5

The presence of organic matter in the medium (e.g. blood, pus or serum) may have a protective effect on the test organims

Question 6

Effect of temperature may be assed by the ____ value

Answer 6

Q10