MEDLINE Journals

    Determination of sulfur amino acids and tryptophan in foods and food and feed ingredients: collaborative study.

    Authors
    Allred MC, MacDonald JL 
    Source
    J Assoc Off Anal Chem 1988 May-Jun; 71(3) :603-6.
    Abstract

    Samples of 4 foods, 1 animal feed, isolated soy protein, and beta-lactoglobulin were analyzed by 9 laboratories to determine concentrations of cysteine as cysteic acid, methionine as methionine sulfone, and tryptophan. Sulfur amino acids were determined by AOAC method 43.A08-43.A13 for food and feed ingredients, in which samples are oxidized with performic acid before protein hydrolysis with 6N HCl. Tryptophan was determined after protein hydrolysis with 4.2N NaOH. In both methods, free amino acids were separated by ion-exchange or reverse-phase chromatography. Each laboratory was provided with detailed methods and with sealed vials containing solutions of standards. Samples were analyzed in duplicate, and variation between laboratories was determined. Coefficients of variation between laboratories for the 6 samples ranged from 5.50 to 11.8% for methionine as methionine sulfoxide, 8.59 to 17.3% for cysteine as cysteic acid, and 3.87 to 16.1% for tryptophan. Amino acid recoveries were determined by analysis of beta-lactoglobulin and were based on expected levels of each amino acid obtained from amino acid sequence data. The mean recovery of cysteine was 97% with a range of 88-119%. For methionine, mean recovery was 98% (range 89-115%) and for tryptophan, 85% (range 59-102%). Method 43.A08-43.A13 for food and feed ingredients has been adopted official first action for determination of cysteine and methionine in processed foods. The alkaline hydrolysis method has been adopted official first action for determination of tryptophan in foods and food and feed ingredients.

    Mesh
    Amino Acids, Sulfur
    Animal Feed
    Chromatography
    Chromatography, Ion Exchange
    Cysteine
    Food Analysis
    Hydrolysis
    Indicators and Reagents
    Methionine
    Tryptophan
    Language

    eng

    Pub Type(s)
    Journal Article
    PubMed ID

    3391969

    Content Manager
    Related Content

    Oxidation and hydrolysis determination of sulfur amino acids in food and feed ingredients: collaborative study.

    Determination of sulfur amino acids in foods as related to bioavailability.

    Analyzing sulfur amino acids in selected feedstuffs using least-squares nonlinear regression.

    [Determination of sulfur-containing amino acids in food products].

    Quantitative analysis of cystine, methionine, lysine, and nine other amino acids by a single oxidation--4 hour hydrolysis method.

    Complete amino acid analysis in hydrolysates of foods and feces by liquid chromatography of precolumn phenylisothiocyanate derivatives.

    Water-soluble vitamins.

    Liquid chromatographic determination of lysine, methionine, and threonine in pure amino acids (feed grade) and premixes: collaborative study.