NMKL News No. 101
NMKL method No. 164, Escherichia coli 0157. Detection in food and animal feed, has been updated.
NMKL method No. 164, Escherichia coli 0157. Detection in food and animal feed, has been updated.
The standardized analytical method for folate in food has traditionally utilized quantification by a microbiological assay, a method that cannot distinguish between the different folate vitamers. This new NMKL method enables quantification of total folate based on quantification of six folate vitamers which contribute to the main folate activity. Besides providing the information about the content of the specific folate vitamers, the method includes fast extraction of folates from food that may be carried out within eight hours.
The essential part of the method is using a pure γ-glutamyl hydrolase, which enables efficient and fast break-down of the polyglutamates to monoglutamates. LC-ESI-MS/MS quantifies monoglutamates by use of 13C5-labelled internal standards.
A collaborative study was conducted in summer 2019 with participation of eight laboratories from seven European countries. The method has been successfully validated for total folate determination in strawberries, spinach, lentils, yogurt, liver and infant formula, providing acceptable Horwitz ratio values (0.60-1.94). The results are published in Food Chemistry (Ložnjak Švarc, P; Oveland, E; Strandler, HS; Kariluoto, S; Campos-Giménez, E; Ivarsen, E; Malaviole, I; Motta, C; Rychlik, M; Striegel, L; Jakobsen, J (2020): Collaborative study: Quantification of total folate in food using an efficient single-enzyme extaction combined with LC-MS/MS. Food Chemistry, 333, 127447).
NMKL method 183 describes sensory quality control of drinking water. Water samples are tested against flavour-neutral reference water. If there are deviations, these are registered and a remark is given according to the nomenclature list in the method. The method is updated to now also include test settings and parameters for appearance. In addition, references have been updated.
NMKL /NordVal International and AOAC International have signed an Agreement of Cooperation that will streamline the process for test kit companies seeking recognition from NordVal International and AOAC simultaneously.
The new agreement allows the two organizations and their respective certification programmes to jointly develop and use common evaluation protocols and select independent testing laboratories.
The goal of the cooperative agreement is to reduce the economic barrier imposed by requiring separate studies. Joint protocols mean method developers will be able to conduct testing once at one laboratory, and the data will be applicable to both AOAC and NMKL. Each organization will conduct reviews, render decisions on approvals of methods and issue certificates.
NMKL method No. 151 Presumptive Shigella spp. Detection in foods has been updated and reintroduced.
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