ISO 4832-2006 PDF

Full title and description

Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of coliforms — Colony-count technique (ISO 4832:2006). This International Standard provides a horizontal (i.e., broadly applicable) colony-count procedure for enumerating coliform bacteria on solid selective media after incubation, applicable to foods, animal feeding stuffs and related environmental samples in the food chain.

Abstract

ISO 4832:2006 gives general guidelines for the enumeration of coliforms using a colony-count technique on a solid medium with incubation at either 30 °C or 37 °C. The method is intended for situations where colony counts are expected to exceed about 100 colonies per millilitre or per gram of sample and is intended for use with food, feed and environmental samples associated with food production and handling.

General information

• Status: Published — International Standard; last systematic confirmation noted in 2021 (stage 90.93), so the 2006 edition remains current as confirmed by ISO.
• Publication date: 16 February 2006 (Edition 3, 2006).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 07.100.30 (Food microbiology).
• Edition / version: Edition 3 (2006).
• Number of pages: 6 pages (official ISO publication).

Scope

This standard provides a colony-count technique for enumeration of coliform bacteria on a solid selective medium after incubation at 30 °C or 37 °C. It applies to products intended for human consumption and animal feeding, and to environmental samples in areas of food production and handling. The chosen incubation temperature (30 °C or 37 °C) may be agreed between parties; for milk and milk products 30 °C is typically used. The method is recommended when expected colony numbers are above ~100 per mL or g.

Key topics and requirements

• Principle: enumeration by direct colony count on a selective solid medium after appropriate dilution and incubation.
• Incubation: specified temperatures of 30 °C or 37 °C (temperature to be agreed; milk commonly at 30 °C).
• When to use: recommended for samples where counts are expected to exceed ~100 coliforms per mL or gram.
• Culture media and quality: refers to general guidance on preparation and performance testing of culture media (normative references include ISO/TS 11133 parts and ISO 6887 series).
• Normative references: ISO 6887 (preparation of test samples and dilutions), ISO 7218 (general microbiological requirements), ISO/TS 11133-1/-2 (culture media preparation and QA).
• Reporting and expression of results: procedures for enumeration, confirmation and expression of counts (including precision reporting) are included or referenced.

Typical use and users

Used by food and feed microbiology laboratories (industrial QC, contract testing, research labs), regulatory and public health laboratories, food manufacturers, dairy processors and standardization bodies. National standards organizations sometimes adopt or adapt ISO 4832 into national documents (for example, AS 5013.4 in Australia adopts/modifies ISO 4832:2006).

Related standards

Normative and related references commonly cited with ISO 4832 include ISO 6887 (all parts — preparation of test samples and dilutions), ISO 7218 (general requirements for microbiological examinations), ISO/TS 11133-1 and -2 (culture media preparation and performance testing), ISO 4831 (most probable number technique for coliforms), and other horizontal colony-count standards such as ISO 4833. National/adopted variants and sector-specific methods (e.g., AS 5013.4) also reference ISO 4832.

Keywords

coliforms, colony-count, enumeration, food microbiology, incubation, VRBL/selected agar, ISO 4832, colony count technique, food safety, microbiological method.

FAQ

Q: What is this standard?

A: ISO 4832:2006 is an International Standard that specifies a horizontal colony-count technique for enumerating coliform bacteria in food, feed and related environmental samples.

Q: What does it cover?

A: It covers the principle, media, sample preparation/dilution, inoculation, incubation (30 °C or 37 °C), colony counting, confirmation steps and expression of results for coliform enumeration where counts are expected to be relatively high (> ~100 per mL or g). Normative references provide guidance on media preparation and sample handling.

Q: Who typically uses it?

A: Food and feed testing laboratories (industry and contract labs), regulatory agencies, dairy and food processors, researchers and standards bodies that adopt or reference ISO microbiological methods.

Q: Is it current or superseded?

A: The ISO record shows ISO 4832:2006 (Edition 3) as published in February 2006 and the publication was last reviewed/confirmed in 2021 (stage 90.93), so the 2006 edition is shown as the current confirmed edition on the ISO catalogue. Users should check the ISO catalogue or national standards body for any later revisions or amendments before relying on the method for regulatory purposes.

Q: Is it part of a series?

A: Yes — ISO 4832 is one of several horizontal methods in the ISO "Microbiology of food and animal feeding stuffs" family (other related standards include ISO 4831 for MPN coliform technique, ISO 4833 for general colony counts, ISO 7218, ISO 6887, ISO/TS 11133 series, etc.). These standards are commonly used together to cover sampling, media preparation, detection and enumeration tasks.

Q: What are the key keywords?

A: Coliforms, enumeration, colony-count, food microbiology, incubation temperature, selective agar, ISO 4832.