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The Protein Digestibility-Corrected Amino Acid Score (PDCAAS) - A concept for describing protein quality in foods and food ingredients: A critical review

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Author: Schaafsma, G.
Type:article
Date:2005
Institution: TNO Kwaliteit van Leven
Source:Journal of AOAC International, 3, 88, 988-994
Identifier: 238480
Keywords: Nutrition · Physiological Sciences · Absorption · Amino acids · Bioassay · Food processing · Food products · Information analysis · Nutrition · Synthesis (chemical) · Digestibility · Gastrointestinal model · Protein digestibility-corrected amino acid score (PDCAAS) · Protein quality · Proteins · amino acid · essential amino acid · protein · trypsin · animal · animal food · bioavailability · body weight · chemistry · chicken · food · food analysis · gastrointestinal tract · human · ileum · metabolism · methodology · nutrition · preschool child · rat · review · Amino Acids · Amino Acids, Essential · Animal Nutrition Physiology · Animals · Biological Availability · Body Weight · Chickens · Child, Preschool · Food · Food Analysis · Gastrointestinal Tract · Humans · Ileum · Nutrition Physiology · Proteins · Rats · Trypsin

Abstract

Protein Digestibility-Corrected Amino Score (PDCAAS) is discussed. PDCAAS is now widely used as a routine assay for protein quality evaluation, replacing the more traditional biological methods [e.g., measurement of the Protein Efficiency Ratio (PER) in rats]. PDCAAS is based on comparison of the essential amino acid content of a test protein with that of a reference essential amino acid pattern and a correction for differences in protein digestibility as determined using a rat assay. Although PDCAAS is a rapid and useful method, it often shows discrepancies when compared to PER values. These discrepancies relate to the following issues: uncertainty about the validity of reference patterns, invalidity of correction for fecal (versus ileal) digestibility, truncation of PDCAAS values to 100%, failure to obtain full biological response after supplementation of the limiting essential amino acid, discrepancies between protein and amino acid digestibility, effects of processing on protein quality, and effects of the presence of antinutritional factors in the matrix containing the protein. Part of the discrepancy between PDCAAS and PER can be overcome by modifications of PDCAAS. This article describes some proposed modifications and puts forward the suggestion that the rat protein fecal digestibility assay be replaced by an in vitro ileal amino acid digestibility assay based on a computer-controlled gastrointestinal model.