ISO 3356-1975 rus PDF

Full title and description

ISO 3356:1975 — Milk and dried milk, buttermilk and buttermilk powder, whey and whey powder — Determination of phosphatase activity (Reference method). This 1975 international standard specifies a reference chemical method for measuring alkaline phosphatase activity used to verify effective pasteurization of the listed dairy products.

Abstract

ISO 3356:1975 describes a phenolic reference method in which a liquid dairy sample (or reconstituted powder) is diluted with a pH 10.6 buffer containing disodium phenylphosphate, incubated at 37 °C for 1 hour, and the phenol liberated by alkaline phosphatase is reacted with dibromop‑quinone‑chloroimide to produce a coloured product measured photometrically. The procedure is intended for control of correct pasteurization. The 1975 edition has since been withdrawn and a revised method is published as ISO 3356:2009.

General information

• Status: Withdrawn (replaced by a later edition).
• Publication date: July 1975.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 67.100.10 (Dairy products — milk and milk products).
• Edition / version: Edition 1 (1975).
• Number of pages: 3.

Scope

The standard applies to milk and milk-derived products listed in the title (liquid milk, dried milk, buttermilk and buttermilk powder, whey and whey powder) and is intended for laboratory determination of alkaline phosphatase activity as an indicator of whether pasteurization has been effective. The method is a quantitative reference chemical assay suitable for samples with activities above the method’s detection limits and for use where an established reference procedure is required.

Key topics and requirements

• Principle: phenylphosphate substrate hydrolysis by alkaline phosphatase; phenol formation and colour development with dibromop‑quinone‑chloroimide; photometric measurement.
• Reagents and buffer conditions: disodium phenylphosphate in a buffer at pH 10.6 specified for the reaction.
• Incubation parameters: typical condition specified is 37 °C for 1 hour for the reference reaction.
• Sample preparation: procedures for dilution or reconstitution of powders to provide comparable results.
• Calculations and expression of results: conversion of absorbance to amount of phenol (µg phenol per mL) and interpretation against acceptance criteria for pasteurization control.
• Performance and applicability: designed as a reference method; laboratories should follow quality‑control and calibration practices when using the assay.

Typical use and users

Used by dairy quality‑control laboratories, regulatory testing bodies, dairy technologists and food‑safety researchers as a reference method to verify pasteurization efficacy and to calibrate or validate faster screening tests for alkaline phosphatase. After withdrawal of the 1975 edition, users are generally directed to the updated ISO 3356:2009 method for current practice.

Related standards

The 1975 reference method was superseded by ISO 3356:2009 (also published as IDF 63:2009), which provides an updated procedure for determination of alkaline phosphatase in milk and related products. National or regional adoptions and implementations of the ISO method exist in various catalogues of standards and national standards bodies.

Keywords

alkaline phosphatase, phosphatase activity, milk, buttermilk, whey, pasteurization control, phenylphosphate method, reference method, ISO 3356, 1975

FAQ

Q: What is this standard?

A: ISO 3356:1975 is an ISO reference method for determination of alkaline phosphatase activity in milk and certain milk products, published in July 1975.

Q: What does it cover?

A: It covers a phenolic quantitative assay based on hydrolysis of disodium phenylphosphate at pH 10.6 with incubation at 37 °C and photometric measurement of the phenol reaction product; it is intended to assess pasteurization effectiveness.

Q: Who typically uses it?

A: Dairy testing laboratories, regulators, standards organisations and research laboratories that require a reference/validated method for alkaline phosphatase in milk and milk products.

Q: Is it current or superseded?

A: The 1975 edition has been withdrawn and superseded by ISO 3356:2009 (IDF 63:2009). Laboratories should consult the 2009 edition for the current internationally‑recommended procedure.

Q: Is it part of a series?

A: It was produced under ISO/TC 34/SC 5 (food products – milk and milk products methods) and is related to other dairy analysis standards; the subject area (ICS) is 67.100.10.

Q: What are the key keywords?

A: Alkaline phosphatase, phosphatase activity, pasteurization, milk testing, phenylphosphate method, photometric determination, ISO 3356.