In most cited food composition studies and tables, the proximate system measures protein as total nitrogen (N) (determined by Kjeldahl or Dumas method) multiplied by a specific factor. A factor of 6.25 is used for determining total protein from total N (Jones, Munsey, & Walker, 1942). Although more expensive, it is considered more accurate to base protein content of foods on amino acid data (Greenfield & Southgate, 2003). A study on the nutrient composition of beef analysed the full amino-acid profile of fifteen retail cuts from three age groups and six fat codes, as well as determined total nitrogen content to determine proximate protein composition. For all cuts, the correlation coefficient of total amino acids to protein (N × 6.25) was 0.635. This indicates a poor correlation for predicting actual protein content (as determined by total amino acid count), based on the nitrogen factor of 6.25. On average, the sum of amino acids per cut amounted to 91% of total determined protein (N × 6.25) for the same cut.
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Amino acid (aa); South african beef
语言
英语
许可
© 2012 Elsevier. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Food Chemistry.Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Food Chemistry, vol. 140, no. 3, 2013. doi.: 10.1016/j.foodchem.2012.08.046
ISSN
0308-8146 (print), 1873-7072 (online)
类型
Journal Article; Journal Part
2025-05-29
2026-02-03
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