NMKL would like to thank Leif Boegh-Soerensen and Kaare Julshamn, and their institutes, for their considerable work in the elaboration and arrangement of the collaborative studies.  

NMKL would also like to thank the all the laboratories who have participated in the studies and the contact persons for their valuable comments and input. 

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NMKL method No 127, 2nd Ed., 2002:

HYDROXYPROLINE. Colorimetric determination as a measure of collagen in meat and meat products.

The method was originally validated in a collaborative study in 1987 performed by Kurt Kolar at Swedish Meats R&D. 18 laboratories participated.

 This method has now been revised by Leif Boegh-Soerensen, Danish Veterinary and Food Administration, Copenhagen, Denmark. Boegh-Soerensen has also arranged a minor collaborative study, with 4 participating laboratories, in order to performance test the modifications of the revised method.  The results from the collaborative study in 1987, as well as the results from the minor study conducted in 2000, are given in an annex to the method.

 The method was primarily revised due to the requirement for an alternative color reagent solution than that described in the previous edition. Perchloric acid was to be replaced with sulphuric acid. Both color reagents are described in the method. The results of the minor study showed no significant difference in the results between the two different color reagents.

The method describes the quantitative determination of hydroxyproline and the estimation of the amount of collagenous connective tissue in meat and meat products.

Connective tissue contains various proteins, collagen being most abundant. Collagen contains 12.5% (w/w) hydroxyproline.

The principle of the method is hydrolysis in sulphuric acid at 103°C. The sample is then filtered and diluted. Hydroxyproline is oxidised with chloramine-T. After the addition of 4-dimethylamino-benzaldehyde, a red-purple colour is developed, which is measured photometrically.

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NMKL method No 169, 2002:

DRY MATTER in foodstuffs. The vacuum method.

Leif Boegh-Soerensen, Danish Veterinary and Food Administration, Copenhagen, Denmark, one of NMKL’s foremost experts, has also elaborated and conducted a collaborative study of this method. Nine laboratories participated in the study, which was performed in 1999. The results are given in the method.

This method describes a routine procedure for the determination of dry matter in foodstuffs.

The sample is dried to constant weight at 70°C under vacuum.

Dry matter is here defined as the substance remaining after completion of this drying process. The dry matter is expressed as percentage by mass (g/100 g).

The results of the study were satisfactory. The method is horizontal. If greater accuracy is required, a method specific for the foodstuff in question should be applied.

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NMKL Method No 170, 2002:

MERCURY. Determination   in Seafood by Flow Injection Cold Vapour Atomic Absorption Spectrometry (FI-CVAAS) after Microwave Digestion.

Kaare Julshamn, Institute of Nutrition, Directorate of Fisheries, Norway, has elaborated the method and administered the collaborative validation. 10 laboratories participated in the study in 1999/2000.

The method is adopted and included in the working programme of AOAC International, as well as that of the European standardisation organisations CEN/TC 275. The collaborative study is to be published in the Journal of AOAC International.

The results of the study are also published as an annex to this method.

The method is applicable to determinations of mercury in freeze- dried samples of fish and various types of seafood products. The method has been tested on concentrations higher than 0.04 mg/kg dry products

The method describes the addition of concentrated nitric acid and hydrogen peroxide (30%) to test samples, which are then digested in a microwave oven. The concentration of mercury is determined by FI-CVAAS, after divalent mercury is reduced to elemental mercury with sodium boron hydride. Mercury content is calculated using external standard calibration and peak height.

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NMKL procedure No 11, 2002:

SENSORIAL EVALUATION OF DRINKING WATER

This NMKL procedure is elaborated within a NMKL project, by project leader and author Urd Bente Andersen, Norwegian Institute for Food and Environmental Analysis.

Other project members:
Denmark: Robert G. Nielsen, Biotechnological Institute 
Finland: Juhani Airo, City of Helsinki, Environment Centre 
Iceland: Tyri Valdimarsdóttir, Icelandic Fisheries Laboratories
Sweden: Ulf Eriksson, VA-prosject, Uppsala

This NMKL document describes a procedure for sensorial analysis of drinking water. The selection and training of sensorial judges, preparations for the analysis, conditions for the sensorial judges, the environment and equipment used in connection with the analysis and the treatment and preparation of the samples are all described. The procedure is meant as a guide for the procedure for the evaluation of drinking water. This document is mainly designed for analysis performed by a sensorial panel at a laboratory, however, it can also be used as a guideline for analysis performed in the field, for example at a sampling point in the water main.

The procedure describes different guidelines that should be followed when evaluating drinking water. However, it is not a method description.  References and brief descriptions of some suitable methods are included, to aid in finding an appropriate method.  At a later date, NMKL is hoping to publish an NMKL method for sensorial evaluation of drinking water.

The procedure is based on national and international recommendations and standards, as well as on the experience of sensorial laboratories.

The procedure is only available in a Scandinavian language at this time, and can be ordered from the NMKL office.

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RECENT METHOD RESOLUTIONS

The following method has been re-included in NMKL’s compiled collection.

NMKL method No 20, 1982, 2. Ed.: "Methods for microbiological examinations of butter".   In the previous edition of NMKL newsletter, it was informed that the annual meeting 2001 had resolved to withdraw this method from the collection, as the national committees of NMKL had assumed that the method was not in use. However, this was an error, and the method has been included again.

The following methods have been withdrawn from NMKL’s compiled collection:

 NMKL method No 82, 1972, 2. Ed, (corr 1980): Methylmercury compounds. Determination in fish

NMKL method No 64, 1967: Solids. Determination in canned kale and spinach

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Correction in NMKL procedure No 10, 2001:

Control of microbiological media.

In section 4.4 "Control of Volume" it states; "A maximum of 1% deviation is accepted."

1% should be replaced by 2% - the maximum acceptable deviation is 2%, which harmonises with NMKL method no 91, 2001: Sampling and pre-treatment of foods and animal feedstuffs, for quantitative microbiological examination.

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New secretary of the Icelandic National Committee of NMKL

NMKL would like to warmly welcome Margrét Geirsdottir, Environment and Food Agency of Iceland, as the new secretary of the Icelandic National Committee of NMKL. We look forward to the cooperation.  NMKL would also like to thank Kolbrun Haraldsdottir for her excellent cooperation over many years.

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NEWS FROM NORDVAL

NordVal has validated and approved one more alternative method:

The Oxoid Listeria Rapid Test FT0401/FT0405 for detection of Listeria species.

NordVal has then approved 9 alternative methods and 3 more methods are in the pipeline. For information about approved methods and about validation of alternative methods, see NordVal’s web pages at www.nmkl.org.

NordVal participate in AOAC International working group about rules for validation of alternative microbiological methods. Simultaneously, NordVal has started elaboration of a protocol for validation of quantitative microbiological methods, which will harmonize with the present revised AOAC draft.

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A minor correction.

In the previous edition of NMKL newsletter, NMKL method no 5, 5th Ed., 2001 was described.  A collaborative validation study of methods for aerobic bacteria and Enterocobacteriaceae on surfaces in food processing and production areas was referred to.  The traditional contact plates and commercially available contact plates mentioned in the bulletin are not alike.

- The commercial contact plates referred to is contact slides.

The collaborative study was published in the Journal of AOAC International 83,2000. This publication also recommends use of contact slides rather than using swabbing and dishes.

Liv Hilde Vårvik Lien,Orion Diagnostica as

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Copyright © NMKL.  Med enerett.
Revidert: 28 september 2005 .