ISO 4134 pdf download

ISO 4134 pdf download.Meat and meat products — Determination of L -(+)-glutamic acid content — Reference method 1 Scope This International Standard specifies a reference method for the determination of the L -(+)-glutamic acid content of meat and meat products, including poultry. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 648, Laboratory glassware — One-mark pipettes. ISO 835-2, Laboratory glassware — Graduated pipettes — Part 2: Pipettes for which no waiting time is specified. ISO 1 042, Laboratory glassware — One-mark volumetric flasks. ISO 1 442, Meat and meat products — Determination of moisture content (Reference method). 3 Terms and definitions For the purposes of this International Standard, the following term and definition apply. 3.1 L -(+)-glutamic acid content of meat and meat products mass fraction of L -(+)-glutamic acid determined according to the procedure described in this International Standard NOTE The L -(+)-glutamic acid content is expressed in percent. 4 Principle The L -(+)-glutamic acid present in a test portion is extracted with perchloric acid solution at a temperature of 0 °C. The extract is centrifuged, decanted and filtered and the pH is adjusted to 1 0,0. Nicotinamide adenine dinucleotide (NAD) is reduced by the L -(+)-glutamic acid in the presence of glutamate dehydrogenase [equation (1 )]. The resultant reduced nicotinamide adenine dinucleotide (NADH) is reacted with iodonitrotetrazolium chloride in the presence of diaphorase [equation (2)]. The resulting formazane is measured at a wavelength of 492 nm and the L -(+)-glutamic acid content is calculated. 5 Reagents Use only reagents of recognized analytical grade, unless otherwise specified. Except for the solutions of inorganic compounds (5.2 and 5.3), store all solutions in stoppered brown glass bottles which have been scrupulously cleaned and steamed or sterilized. 5.1 Water, double-distilled, or demineralized and distilled water, obtained by carrying out the final distillation in an all-glass apparatus. NOTE Water distilled only once may contain metal ion traces, and demineralized water may...