GB/T 18634-2009 in English

《GB/T 18634-2009饲用植酸酶活性的测定 分光光度法》由TC76（全国饲料工业标准化技术委员会）归口，主管部门为国家标准化管理委员会。
本标准规定了以分光光度法测定饲用植酸酶的活性。
本标准适用于作为饲料添加剂使用的植酸酶产品，也适用于添加有植酸酶的配合饲料。方法最低定量限为１３０Ｕ／ｋｇ。

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