EN ISO 4833-2:2013

Microbiology of the food chain - Horizontal method for the enumeration of microorganisms - Part 2: Colony count at 30 degrees C by the surface plating technique (ISO 4833-2:2013)

ISO 4833-2:2013 specifies a horizontal method for enumeration of microorganisms that are able to grow and form colonies on the surface of a solid medium after aerobic incubation at 30 °C. The method is applicable to:
a)    products intended for human consumption or for animal feed;
b)    environmental samples in the area of food and feed production and food handling.
ISO 4833-2:2013 is applicable to:
1)    products containing heat-sensitive organisms that are likely to form a significant proportion of the total flora (e.g. psychrotrophic organisms in chilled and frozen foods, dried foods, other foods that may contain heat-sensitive organisms);
2)    products containing obligately aerobic bacteria that are likely to form a significant proportion of the total flora (e.g. Pseudomonas spp.);
3)    products that contain small particles that can prove difficult to distinguish from colonies in a pour plate;
4)    products whose intense colour prevents the recognition of colonies in a pour plate;
5)    products for which distinction between different types of colony is required as part of the assessment of food quality.
In addition to the manual spread plating technique, an annex to ISO 4833-2:2013 also specifies the use of a spiral plater, a rapid method of performing surface colony counts.
The applicability of ISO 4833-2:2013 to the examination of certain fermented food and animal feeds is limited and other media or incubation conditions can be more appropriate. However, this method can be applied to such products even though it is possible that the predominant microorganisms in these products are not detected effectively.
For some matrices, the method described in ISO 4833-2:2013 can give different results to those obtained using the method described in ISO 4833‑1.

Mikrobiologie der Lebensmittelkette - Horizontales Verfahren für die Zählung von Mikroorganismen - Teil 2: Koloniezählung bei 30 °C mittels Oberflächenverfahren (ISO 4833-2:2013)

Dieser Teil der ISO 4833 legt ein horizontales Verfahren zur Zählung von nach aerober Bebrütung bei 30 °C auf der Oberfläche eines festen Mediums wachsenden und Kolonien bildenden Mikroorganismen fest. Das Verfahren gilt für:
a) Produkte, die für den menschlichen Verzehr oder als Futtermittel bestimmt sind;
b) Umgebungsproben im Bereich der Herstellung und Handhabung von Lebens- und Futtermitteln.
Der vorliegende Teil der ISO 4833 gilt für:
1) Produkte, die wärmeempfindliche Mikroorganismen enthalten, die wahrscheinlich einen signifikanten Anteil der Gesamtflora ausmachen (z. B. psychrotrophe Mikroorganismen in gekühlten und gefrorenen Lebensmitteln, getrockneten Lebensmitteln und anderen Lebensmitteln, die möglicherweise wärmeempfindliche Mikroorganismen enthalten);
2) Produkte, die obligat aerobe Bakterien enthalten, die wahrscheinlich einen signifikanten Anteil der Gesamtflora ausmachen (z. B. Pseudomonas spp.);
3) Produkte, die kleine Partikel enthalten, die möglicherweise schwer von Kolonien auf einer Gussplatte zu unterscheiden sind;
4) Produkte, deren intensive Färbung das Erkennen von Kolonien auf einer Gussplatte verhindern würde;
5) Produkte, für die als Teil der Bewertung der Lebensmittelqualität eine Unterscheidung zwischen verschiedenen Arten von Kolonien erforderlich ist.
Zusätzlich zum manuellen Spatelplattenverfahren beschreibt dieser Teil der ISO 4833 die Anwendung eines Spiralplaters, einer schnellen Art der Zählung von Kolonien im Oberflächenverfahren (Anhang A).
Die Anwendbarkeit dieses Teils der ISO 4833 zur Untersuchung bestimmter fermentierter Lebens- und Futtermittel ist begrenzt und andere Medien oder Bebrütungsbedingungen sind möglicherweise geeigneter. Dennoch kann dieses Verfahren auf derartige Produkte angewendet werden, selbst wenn die hauptsächlich in diesen Produkten vorkommenden Mikroorganismen möglicherweise nicht effektiv nachgewiesen werden können.
Für einige Matrizes kann das in diesem Teil der ISO 4833 beschriebene Verfahren zu Ergebnissen führen, die von den mit dem Verfahren nach ISO 4833-1 erhaltenen abweichen.

Microbiologie de la chaîne alimentaire - Méthode horizontale pour le dénombrement des micro-organismes - Partie 2: Comptage des colonies à 30 degrés C par la technique d'ensemencement en surface (ISO 4833-2:2013)

L'ISO 4833-2:2013 spécifie une méthode horizontale de dénombrement des micro-organismes capables de se développer et de former des colonies à la surface d'un milieu solide après incubation aérobie à 30 °C. La méthode est applicable:
a)    aux produits destinés à la consommation humaine ou aux aliments pour animaux;
b)    aux échantillons d'environnement dans le domaine de la production d'aliments destinés à l'homme ou aux animaux et de la préparation des aliments.
L'ISO 4833-2:2013 est applicable:
1)    aux produits contenant des organismes sensibles à la chaleur susceptibles de former une partie significative de l'ensemble de la flore (par exemple des organismes psychrotrophes présents dans des aliments réfrigérés et congelés, des aliments secs, d'autres aliments pouvant contenir des organismes sensibles à la chaleur);
2)    aux produits contenant des bactéries aérobies susceptibles de former une partie significative de l'ensemble de la flore (par exemple Pseudomonas spp.);
3)    aux produits contenant de petites particules qu'il peut se révéler difficile de distinguer des colonies dans une boîte ensemencée en profondeur;
4)    aux produits dont la couleur intense empêche la reconnaissance des colonies dans une boîte ensemencée en profondeur;
5)    aux produits pour lesquels il est nécessaire de faire la différence entre les différents types de colonies dans le cadre de l'évaluation de la qualité des aliments.
En plus de la technique d'ensemencement en surface manuelle, une annexe de l'ISO 4833-2:2013 spécifie également l'utilisation d'un dispositif d'ensemencement en spirale, méthode rapide de dénombrement des colonies en surface.
L'ISO 4833-2:2013 peut ne pas être adaptée à l'analyse de certains aliments fermentés et aliments pour animaux et d'autres milieux ou conditions d'incubation peuvent être plus appropriés. Toutefois, cette méthode peut être appliquée à de tels produits, même si elle ne détecte pas totalement les micro-organismes présents en majorité dans ces produits.
Pour certaines matrices, la méthode décrite dans l'ISO 4833-2:2013 peut donner des résultats différents de ceux obtenus avec la méthode décrite dans l'ISO 4833-1.

Mikrobiologija v prehranski verigi - Horizontalna metoda za ugotavljanje števila mikroorganizmov - 2. del: Štetje kolonij pri 30 oC s tehniko nasajanja na površino (ISO 4833-2:2013)

Ta del standarda ISO 4833 določa horizontalno metodo za ugotavljanje števila mikroorganizmov, ki lahko rastejo in tvorijo kolonije na trdem mediju po aerobni inkubaciji pri 30 °C. Ta metoda se uporablja za: a) izdelke za prehrano ljudi in živalsko krmo; b) okoljske vzorce v območju proizvodnje in oskrbe s hrano in krmo. Ta del standarda ISO 4833 se uporablja za: 1) izdelke, ki so občutljivi na toploto in za katere se predvideva, da bodo tvorili znaten delež celotne flore (npr. psihotrofni organizmi v ohlajeni in zmrznjeni hrani. suhi hrani, hrani, ki morda vsebuje organizme, občutljive na toploto); 2) izdelke, ki obvezno vsebujejo aerobne bakterije, za katere se predvideva, da bodo tvorile znaten delež celotne flore (npr. Pseudomonas spp.); 3) izdelke, ki vsebujejo majhne delce, ki jih je na petrijevki težko razlikovati od kolonij; 4) izdelke, katerih intenzivna barva preprečuje razpoznavanje kolonij na petrijevki; 5) izdelke, za katere je za oceno kakovosti hrane zahtevano razlikovanje med različnimi vrstami kolonij. Poleg ročne tehnike z uporabo petrijevke ta del standarda ISO 4833 navaja uporabo spiralne petrijevke, ki predstavlja hitro metodo za štetje kolonij na površini (Dodatek A). Uporaba tega dela standarda ISO 4833 za preiskovanje določenih vrst fermentirane hrane in živalske krme je omejena in je za to mogoče bolj primeren drug medij ali inkubacijski pogoji. Toda ta metoda se lahko uporabi za te izdelke, čeprav se glavnih mikroorganizmov v teh izdelkih morda ne da učinkovito zaznati. Pri nekaterih matricah lahko metoda, opisana v temu delu standarda ISO 4833, da drugačne rezultate rezultatov, pridobljenih z metodo, opisano v standardu ISO 4833-1.

General Information

• Status: Published
• Publication Date: 03-Sep-2013
• Withdrawal Date: 03-Mar-2014
• ICS: 07.100.30 - Food microbiology
• ICS: 65.120 - Animal feeding stuffs
• Technical Committee: CEN/TC 463 - Microbiology of the food chain
• Drafting Committee: CEN/TC 463 - Microbiology of the food chain
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 04-Sep-2013
• Completion Date: 04-Sep-2013
• Ref Project: SIST EN ISO 4833-2:2013 - Microbiology of the food chain - Horizontal method for the enumeration of microorganisms - Part 2: Colony count at 30 degrees C by the surface plating technique (ISO 4833-2:2013)

Relations

• Replaces: EN ISO 4833:2003 - Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of microorganisms - Colony-count technique at 30 degrees C (ISO 4833:2003)
• Effective Date: 08-Jun-2022
• Amended By: EN ISO 4833-2:2013/A1:2022 - Microbiology of the food chain - Horizontal method for the enumeration of microorganisms - Part 2: Colony count at 30 °C by the surface plating technique - Amendment 1: Clarification of scope (ISO 4833-2:2013/Amd 1:2022)
• Effective Date: 16-Aug-2017
• Corrected By: EN ISO 4833-2:2013/AC:2014 - Microbiology of the food chain - Horizontal method for the enumeration of microorganisms - Part 2: Colony count at 30 degrees C by the surface plating technique - Technical Corrigendum 1 (ISO 4833-2:2013/Cor 1:2014)
• Effective Date: 29-Jan-2014

Overview

EN ISO 4833-2:2013 - "Microbiology of the food chain - Horizontal method for the enumeration of microorganisms - Part 2: Colony count at 30 °C by the surface plating technique" specifies a horizontal laboratory method for enumerating microorganisms that grow and form colonies on the surface of a solid medium after aerobic incubation at 30 °C. The method is intended for foods, animal feeds and environmental samples from food/feed production and handling areas.

Key topics and technical requirements

• Principle: Surface plating of a defined test portion (or initial suspension) onto agar plates, incubation at 30 °C and colony counting to calculate cfu per g or mL. Plates with fewer than 300 colonies are used for calculation.
• Incubation: Aerobic, 30 °C for 72 h (± specified tolerances within the standard).
• Culture medium: Plate Count Agar (PCA) is specified as the non‑selective agar for surface counts; preparation, pH adjustment and quality/performance testing are covered.
• Sample preparation and diluents: Follow ISO 6887 and relevant specific product standards for test portion, initial suspension and decimal dilutions.
• Alternative plating: The standard includes an Annex A describing use of a spiral plater, a rapid surface plating option as an alternative to manual spread plating.
• Performance and limitations:
  • Applicable to heat‑sensitive organisms (e.g., psychrotrophs), obligately aerobic bacteria (e.g., Pseudomonas spp.), coloured or particle‑rich matrices where pour plating is problematic, and when colony differentiation on the surface is needed.
  • Limited applicability for some fermented foods and certain animal feeds - other media/incubation conditions may be more appropriate and predominant organisms in these matrices may not be detected effectively.
  • Results may differ from ISO 4833‑1 (pour plate technique) for some matrices.

Practical applications and users

This standard is used by:

• Food and feed microbiology laboratories for routine total viable count (TVC) by surface plating.
• Quality assurance / QC teams in food and feed manufacturing for product release, shelf‑life studies and hygiene monitoring.
• Regulatory agencies and inspection bodies for standardized enumeration methods.
• Environmental monitoring programs in food production and handling environments where surface counts are required.

Benefits include clearer colony morphology for differentiation, suitability for heat‑sensitive and particle‑containing products, and an option for faster processing via spiral plating.

Related standards

• ISO 4833‑1 (pour plate technique)
• ISO 6887 (sample preparation and dilutions)
• ISO 7218 (general microbiological guidance)
• ISO 11133 (culture media preparation and performance)

Keywords: EN ISO 4833-2:2013, colony count, surface plating, plate count agar, spiral plater, aerobic incubation 30 °C, food microbiology, enumeration of microorganisms.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2013
1DGRPHãþD
SIST EN ISO 4833:2003
Mikrobiologija v prehranski verigi - Horizontalna metoda za ugotavljanje števila
mikroorganizmov - 2. del: Štetje kolonij pri 30 oC s tehniko nasajanja na površino
(ISO 4833-2:2013)
Microbiology of the food chain - Horizontal method for the enumeration of
microorganisms - Part 2: Colony count at 30 degrees C by the surface plating technique
(ISO 4833-2:2013)
Mikrobiologie von Lebensmitteln und Futtermitteln - Horizontales Verfahren für die
Zählung von Mikroorganismen - Teil 2: Koloniezählung bei 30 °C mittels
Oberflächenverfahren (ISO 4833-2:2013)
Microbiologie de la chaîne alimentaire - Méthode horizontale pour le dénombrement des
micro-organismes - Partie 2: Comptage des colonies à 30 degrés C par la technique
d'ensemencement en surface (ISO 4833-2:2013)
Ta slovenski standard je istoveten z: EN ISO 4833-2:2013
ICS:
07.100.30 Mikrobiologija živil Food microbiology
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 4833-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2013
ICS 07.100.30 Supersedes EN ISO 4833:2003
English Version
Microbiology of the food chain - Horizontal method for the
enumeration of microorganisms - Part 2: Colony count at 30
degrees C by the surface plating technique (ISO 4833-2:2013)
Microbiologie de la chaîne alimentaire - Méthode Mikrobiologie von Lebensmitteln und Futtermitteln -
horizontale pour le dénombrement des micro-organismes - Horizontales Verfahren für die Zählung von
Partie 2: Comptage des colonies à 30 degrés C par la Mikroorganismen - Teil 2: Koloniezählung bei 30 °C mittels
technique d'ensemencement en surface (ISO 4833-2:2013) Oberflächenverfahren (ISO 4833-2:2013)
This European Standard was approved by CEN on 26 July 2013.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4833-2:2013: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 4833-2:2013) has been prepared by Technical Committee ISO/TC 34 "Food
products" in collaboration with Technical Committee CEN/TC 275 “Food analysis - Horizontal methods” the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by March 2014, and conflicting national standards shall be withdrawn at
the latest by March 2014.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 4833:2003, together with EN ISO 4833-1:2013.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 4833-2:2013 has been approved by CEN as EN ISO 4833-2:2013 without any modification.
INTERNATIONAL ISO
STANDARD 4833-2
First edition
2013-09-01
Microbiology of the food chain —
Horizontal method for the
enumeration of microorganisms —
Part 2:
Colony count at 30 °C by the surface
plating technique
Microbiologie de la chaîne alimentaire — Méthode horizontale pour
le dénombrement des micro-organismes —
Partie 2: Comptage des colonies à 30 °C par la technique
d’ensemencement en surface
Reference number
ISO 4833-2:2013(E)
©
ISO 2013
ISO 4833-2:2013(E)
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

ISO 4833-2:2013(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 2
5 Culture media and diluents . 2
5.1 General . 2
5.2 Diluents . 2
5.3 Agar medium: plate count agar (PCA) . 2
6 Apparatus . 3
7 Sampling . 4
8 Preparation of test sample . 4
9 Procedure. 4
9.1 Test portion, initial suspension and dilutions . 4
9.2 Inoculation and incubation . 4
9.3 Counting of colonies . 5
10 Expression of results . 5
11 Test report . 5
Annex A (normative) Surface colony count using a spiral plater. 6
Bibliography .12
ISO 4833-2:2013(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2, www.iso.org/directives.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received, www.iso.org/patents.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
The committee responsible for this document is ISO/TC 34, Food products, Subcommittee SC 9,
Microbiology.
This first edition, together with ISO 4833-1, cancels and replaces ISO 4833:2003.
ISO 4833 consists of the following parts, under the general title Microbiology of the food chain —
Horizontal method for the enumeration of microorganisms:
— Part 1: Colony count at 30 °C by the pour plate technique
— Part 2: Colony count at 30 °C by the surface plating technique
iv © ISO 2013 – All rights reserved

INTERNATIONAL STANDARD ISO 4833-2:2013(E)
Microbiology of the food chain — Horizontal method for
the enumeration of microorganisms —
Part 2:
Colony count at 30 °C by the surface plating technique
1 Scope
This part of ISO 4833 specifies a horizontal method for enumeration of microorganisms that are able to
grow and form colonies on the surface of a solid medium after aerobic incubation at 30 °C. The method
is applicable to:
a) products intended for human consumption or for animal feed;
b) environmental samples in the area of food and feed production and food handling.
This part of ISO 4833 is applicable to:
1) products containing heat-sensitive organisms that are likely to form a significant proportion of the
total flora (e.g. psychrotrophic organisms in chilled and frozen foods, dried foods, other foods that
may contain heat-sensitive organisms);
2) products containing obligately aerobic bacteria that are likely to form a significant proportion of
the total flora (e.g. Pseudomonas spp.);
3) products that contain small particles that can prove difficult to distinguish from colonies in a pour plate;
4) products whose intense colour prevents the recognition of colonies in a pour plate;
5) products for which distinction between different types of colony is required as part of the assessment
of food quality.
In addition to the manual spread plating technique, this part of ISO 4833 also specifies the use of a spiral
plater, a rapid method of performing surface colony counts (Annex A).
The applicability of this part of ISO 4833 to the examination of certain fermented food and animal feeds
is limited and other media or incubation conditions can be more appropriate. However, this method can
be applied to such products even though it is possible that the predominant microorganisms in these
products are not detected effectively.
For some matrices, the method described in this part of ISO 4833 can give different results to those
obtained using the method described in ISO 4833-1.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 6887 (all parts), Microbiology of food and animal feeding stuffs — Preparation of test samples, initial
suspension and decimal dilutions for microbiological examination
ISO 7218, Microbiology of food and animal feeding stuffs — General requirements and guidance for
microbiological examinations
ISO 4833-2:2013(E)
ISO 11133, Microbiology of food, animal feed and water — Preparation, production, storage and performance
testing of culture media
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
microorganism
entity of microscopic size, encompassing bacteria, fungi, protozoa and viruses
[SOURCE: ISO/TS 11139:2006, 2.26]
Note 1 to entry: For the purposes of this part of ISO 4833, microorganisms are bacteria, yeasts and moulds that
are able to produce colonies under the conditions specified in this part of ISO 4833.
4 Principle
A specified quantity of the test sample, or a specified quantity of an initial suspension in the case of
other products, is surface plated on a solid agar culture medium contained in Petri dishes.
Other plates are prepared under the same conditions using decimal dilutions of the test sample or of the
initial suspension.
The plates are incubated under aerobic conditions at 30 °C for 72 h.
The number of microorganisms per gram of sample or the number of microorganisms per millilitre of
sample is calculated from the number of colonies obtained on the plates containing fewer than 300 colonies.
5 Culture media and diluents
5.1 General
Follow ISO 11133 for the preparation, production and performance testing of culture media.
5.2 Diluents
Use the diluent(s) specified in ISO 6887 for the product concerned or the specific International Standard
dealing with the product under examination.
5.3 Agar medium: plate count agar (PCA)
5.3.1 Composition
Enzymatic digest of animal tissues 5,0 g
Yeast extract 2,5 g
Glucose, anhydrous (C H O ) 1,0 g
6 12 6
a
Agar 9 g to 18 g
Water 1 000 ml
a
Depending on the gel strength of the agar.
When dairy products are examined, add skimmed milk powder at 1,0 g/l of the culture medium. The
skimmed milk powder shall be free from inhibitory substances.
2 © ISO 2013 – All rights reserved

ISO 4833-2:2013(E)
5.3.2 Preparation
Dissolve the components or the dehydrated complete medium in the water, by heating if necessary. Mix
thoroughly and leave to stand for several minutes.
Adjust the pH (6.5), if necessary, so that after sterilization it is 7,0 ± 0,2 at 25 °C.
Dispense the medium into flasks or bottles (6.9) of suitable capacity. Sterilize in an autoclave (6.1) at
121 °C for 15 min.
If the medium is to be used immediately, cool it in a water bath (6.4) maintained at 47 °C to 50 °C before
use. If not, allow the medium to solidify in the flask or bottle. Before use, melt the medium completely in
a boiling water bath, then cool it in the water bath (6.4) maintained at 47 °C to 50 °C.
5.3.3 Preparation of agar plates
Pour 15 ml to 20 ml of the medium into sterile Petri dishes (6.6) and allow to solidify.
The plates may be stored at (5 ± 3) °C for up to 4 weeks.
Immediately before use, the agar plates should be dried in accordance with ISO 11133.
5.3.4 Performance testing of the culture medium
5.3.4.1 General
Plate count agar is a non-selective medium, used in this part of ISO 4833 as a pre-poured plate for surface
inoculation. Productivity shall be tested according to ISO 11133.
5.3.4.2 Productivity
Incubation (30 ± 1) °C for (72 ± 3) h
a
Control strains Escherichia coli WDCM 00013 or WDCM 00012 [World Data Centre for Microor-
ganisms (WDCM)]
a
...