Science & Research

Volume IV - 2.8 Alkaline Phosphatase

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Orientation and Training
Food and Drug Administration



Section 2 - Microbiology



A. Objective

Detect levels of alkaline phosphatase in dairy products using both the BAM screening method and the AOAC confirmation method.

B. Assignment

It is the trainer’s primary responsibility to transfer knowledge both practical and in theory related to sample analysis. This may be accomplished through a series of designated training samples. Once the trainer is confident that the trainee can successfully and independently perform the analysis, the trainee will be issued a series of training samples.

Read Bacteriological Analytical Manual (BAM), online at:

Analyze 5 cheese samples for alkaline phosphatase. The trainer will supply samples with known levels of alkaline phosphatase. Samples with violative alkaline phosphatase levels will be confirmed with the AOAC confirmation method.

C. Questions

  1. Why is the presence of alkaline phosphatase determined in dairy products?
  2. What is the reason for heating the control blank?
  3. Why is a buffer used in the analysis? In the AOAC confirmation method, why are different buffer and precipitant concentrations used for different cheeses?
  4. What parameters need to be controlled for the phenol to be liberated from the disodium phenyl phosphate substrate?
  5. To what compound is the alkaline phosphatase enzyme activity proportional?
  6. Describe the reaction that takes place in order for phenol to be measured colorimetrically?

Page Last Updated: 07/14/2015
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