Tryptophan determination in milk-based ingredients and dried sport supplements by liquid chromatography with fluorescence detection

Sport supplements formulas are driven to a sector of consumers which a restrictive diet. Tryptophan is essential amino acid and its bioavailability should be assessed from these commercial products. A robust and fast HPLC procedure is applied to determine total tryptophan content from dairy-ingredients, mostly whey-based ingredients, and commercial dried-sport supplements, mostly whey-enriched sport supplements. The nutritional quality of the protein used in the formulation could be extrapolated to the expected tryptophan content by using a regression curve built from milk-based ingredients. Samples that not conform the correlation are suspected from inadequate industrial practices, such as over-processing, and/or the use of heat-damage ingredients. 2005 Elsevier Ltd. All rights reserved.