Appendix E

Volumes 1-3
September 1993

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Enzyme treatment of foods for filtration

1. Foods tested at dilutions of 1:100 or higher do not actually need enzyme treatment. When preparing dilutions, use the diluent (0.1% peptone water (PEP) or 0.1% peptone-1.0% Tween 80 (PT) suggested in Tables 1-7. IF THE SPREADFILTER IS TO BE USED TO FILTER THE SAMPLE, USE PT.

2. IF USING EZ^TM ENZYMES (GELMAN SCIENCES, MONTREAL, QUE) PROCEED AS FOLLOWS:¹

3. Use the enzyme treatment recommended in Tables 1-7.

4. Reconstitute a bottle of EZ^TM Enzyme by adding 100 ml sterile water to the bottle and shaking well.

Store unused reconstituted enzyme as directed on the label.

5. Combine in a sterile tube 5 ml of sample homogenate and 1 ml reconstituted EZ^TM Enzyme to give the desired final enzyme concentration.

6. Incubate in a 35^oC waterbath for 20-30 minutes.

7. Vortex tube to resuspend sample and proceed with the analyses.

8. Filter 1.2 ml of the enzyme-treated homogenate instead of 1.0 ml to retain a dilution factor of 10.

9. IF USING SIGMA ENZYMES (SIGMA CHEMICAL CO, ST. LOUIS MO), PROCEED AS FOLLOWS:

10. Use the enzyme treatment recommended in Table 8. Prepare enzyme stock solutions as in Step
14.

11. Combine 5 ml of the 1:10 dilution with 1 ml of enzyme stock solution.

12. Incubate in a 35^oC waterbath for 20 min.

13. Filter 1.2 ml of the enzyme-treated homogenate to retain dilution factor of 10.

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¹With thanks to QA Life Sciences Inc, San Diego, CA, USA, for permission to use copyright material.