Determination of feed phytase activity - Spectrophotometric method
1 Scope
This standard stipulates the determination of feed phytase activity by spectrophotometric method.
This standard is applicable to the phytase products used as feed additives, and also to the formula feeds added with phytase. The lowest limit of quantification in the method is 130 U/kg.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections) to, or revisions, of any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document applies.
GB/T 14699.1 Animal feeding stuffs - Sampling
3 Terms and definitions
For the purposes of this standard, the following term and definition apply.
3.1
phytase activity
1 μmol of inorganic phosphorus is released from the 5.0 mmol/L sodium phytate solution per minute at 37℃ and pH 5.50, which is regarded as a phytase activity unit, expressed as U
4 Principle
Phytase hydrolyzes the substrate sodium phytate at a certain temperature and pH to produce orthophosphoric acid and inositol derivatives, which can form a yellow complex with ammonium vanadium molybdate, which can be can determined by colorimetry at the wavelength of 415 nm.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Reagents and materials
6 Apparatus
7 Specimen preparation
8 Determination steps
9 Calculation and expression of results
Annex A (Informative) Recommended sample amounts
