Protein digestibility-corrected amino acid scores (PDCAAS) for soy protein isolates and concentrate: criteria for evaluation.
Level 5 - mechanism / opinion, no new human data
Bench/laboratory analytical comparison study without human clinical data (Level 5 by CEBM design analogy)
PubMed 22017752 · doi:10.1021/jf203220v
What was done
PDCAAS (protein digestibility-corrected amino acid score) values were evaluated for four processed soy ingredients—three isolated soy proteins (ISP) and one soy protein concentrate (SPC). Amino acid profiling and true digestibility measurements were compared across two independent laboratories to assess the impact of analytical method accuracy and reproducibility.
What was found
Amino acid values from the first laboratory produced a truncated PDCAAS score of 1.00 for all four ingredients. The second laboratory yielded statistically significantly lower PDCAAS scores, ranging from 0.95 to 1.00. The authors found that analytical method error substantially contributes to these discrepancies and can be mitigated by applying amino acid nitrogen recovery correction factors.
Why it matters
It shows that published differences in soy protein quality scores can result from laboratory measurement artifacts rather than intrinsic ingredient differences, supporting standard nitrogen recovery corrections.
Limits
The analysis was restricted to four soy ingredients tested at only two laboratories. The abstract reports no human in vivo data, raw amino acid recovery metrics, or exact confidence intervals.
Cited by
- supports Soy contains all essential amino acids and is a complete protein capable of supporting human nutritional requirements without meat.