Protein quality, as determined by the PDCAAS method, is a measure of a protein's ability to provide adequate levels of essential amino acids for human needs. PDCAAS is calculated using an amino acid profile and true digestibility of a food protein. Soy protein is recognized as a high quality plant protein, but published PDCAAS values may vary based on the soy protein ingredient as well as the reproducibility and accuracy of the testing methods. Comparison of PDCAAS values for four differently processed soy ingredients, including three isolated soy proteins (ISP) and one soy protein concentrate (SPC), was made using two different laboratories with evaluation of the impact of the reproducibility and accuracy of amino acid profiles. PDCAAS calculations, using amino acid values from one laboratory, yielded a truncated PDCAAS of 1.00 for all four ingredients, while a second laboratory provided statistically significantly lower scores (0.95-1.00). We conclude that analytical method error can be a significant contributor to PDCAAS differences and can be mitigated by the application of amino acid nitrogen recovery correction factors.

The validity of the protein digestibility-corrected amino acid score (PDCAAS) method in predicting the quality of fourteen protein products was compared with the commonly used protein quality methods, protein efficiency ratio (PER) and net protein ratio (NPR). A rat growth and balance study was conducted to determine protein digestibility and quality of the animal and vegetable protein products by the PER and NPR methods. Amino acid compositions of the products were also determined, and PDCAAS were calculated using a rat and a human pattern of amino acid requirements. Compared to the biological methods, the scoring method overestimated protein quality of mustard flour [PDCAAS of 84-92% vs. relative PER (RPER) or relative NPR (RNPR) of 0], raw black beans (PDCAAS of 45-72% vs. RPER or RNPR of 0), alkaline-treated lactalbumin and soybean protein isolate (PDCAAS of 44-67% vs. RPER or RNPR of 0) and heated skim milk (PDCAAS of 29-31% vs. RPER and RNPR of 0-5%). The scoring method also overestimated the protein quality of zein (true protein digestibility of 63%) supplemented with Lys, Met, Thr and Trp (PDCAAS of 63-71% vs. RPER and RNPR of 3-44%). These data demonstrate that the PDCAAS method is inappropriate for predicting protein quality of those protein sources which may contain naturally occurring growth-depressing factors or antinutritional factors formed during alkaline and/or heat processing.

Seven different in vitro methods to determine the protein digestibility for chickpea proteins were considered and also the application of these methodologies for calculating PDCAAS (protein digestibility-corrected amino acid score), seeking their correlations with the in vivo methodology. In vitro digestibility of raw and heated samples were determined using pepsin-pancreatin hydrolysis, considering soluble nitrogen via Kjeldahl (ppKJ) and hydrolysed peptide linkages using trinitrobenzenesulfonic acid and o-phthaldialdehyde. In vitro digestibility was also determined using trypsin, chymotrypsin and peptidase (3-Enz) or trypsin, chymotrypsin, peptidase and pronase solution (4-Enz). None of the correlations between in vitro and in vivo digestibilities were significant (at p<0.0500), but, strong correlations were observed between PDCAAS calculated by in vitro and in vivo results. PDCAAS-ppKJ, PDCAAS-3-Enz and PDCAAS-4-Enz presented the highest correlations with in vivo method, r=0.9316, 0.9442 and 0.9649 (p<0.0500), respectively. The use of in vitro methods for calculating PDCAAS may be promising and deserves more discussions.

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.

Vegetable proteins are an integral part of infant weaning diets in Latin America. Protein quality in plant-based products, however, is constrained by amino acid composition and intrinsically present antinutritional factors. The goal of this study was to improve bean protein quality by utilizing fermentation and germination processing. The objectives were to determine if protein quality, as measured by Food and Agricultural Organization (FAO) approved True Protein Digestibility (TPD) and Protein Digestibility-Corrected Amino Acid Scores (PDCAAS), of formulated bean-based weaning products could be improved upon fermentation and germination and if protein quality could be further improved when processed beans were combined with cooked rice. Results showed that the highest TPD and PDCAAS values were obtained for cooked germinated beans combined with rice. The TPD values for products ranged from 80 to 91%, and the PDCAAS values were 0.38-0.51. There was no significant increase (P < 0.05) of either TPD or PDCAAS values upon fermentation. Germination increased TPD of cooked bean products; this increase was not, however, accompanied by an increase in PDCAAS. When combined with rice, the PDCAAS values for all bean products improved significantly, thus supporting the concept of cereal-legume complementation. In conclusion, this study showed the range of PDCAAS in processed black bean and bean-rice infant weaning food products. The potential for incorporation of these products into the diets of weaning age Latin American children would, however, be confirmed only after validation with growth or metabolic balance studies in human infants.

El escore de una proteína refleja su contenido en aminoácidos (AA) en comparación con la proteína ideal. Sin embargo, cuando se necesita conocer la utilización de los AA en el organismo es necesario realizar la corrección del valor de escore según la digestibilidad proteica (PDCAAS). Debido a que tal información no se encuentra disponible para los alimentos de consumo habitual, el presente trabajo tuvo como objetivo calcular en los mismos el valor de PDCAAS. El escore de una proteína refleja su contenido en aminoácidos (AA) en comparación con la proteína ideal. Sin embargo, cuando se necesita conocer la utilización de los AA en el organismo es necesario realizar la corrección del valor de escore según la digestibilidad proteica (PDCAAS). Debido a que tal información no se encuentra disponible para los alimentos de consumo habitual, el presente trabajo tuvo como objetivo calcular en los mismos el valor de PDCAAS. El escore se obtuvo calculando el AA limitante en 70 alimentos, tomando como proteína de referencia el patrón de aminoácidos para niños > de 1 año y adultos propuesto por la Academia Nacional de Ciencias EEUU en el año 2002. El valor de PDCAAS se obtuvo en cada caso multiplicando el dato de el escore por la cifra de digestibilidad. En los alimentos de origen vegetal, los valores obtenidos de escore y PDCAAS fueron respectivamente: hortalizas del 88,5% / 73,4%, tubérculos 89,44% / 74,24%, frutas frescas: 75,6% / 64,3%, frutas secas: 65,6% / 48,1, legumbres en general: 89,2% / 69,58%, garbanzos y soja: 100% / 78%, cereales y derivados: 68,8% / 58,5%.El escore se obtuvo calculando el AA limitante en 70 alimentos, tomando como proteína de referencia el patrón de aminoácidos para niños > de 1 año y adultos propuesto por la Academia Nacional de Ciencias EEUU en el año 2002. El valor de PDCAAS se obtuvo en cada caso multiplicando el dato de el escore por la cifra de digestibilidad. En los alimentos de origen vegetal, los valores obtenidos de escore y PDCAAS fueron respectivamente: hortalizas del 88,5% / 73,4%, tubércupalos 89,44% / 74,24%, frutas frescas: 75,6% / 64,3%, frutas secas: 65,6% / 48,1, legumbres en general: 89,2% / 69,58%, garbanzos y soja: 100% / 78%, cereales y derivados: 68,8% / 58,5%. La confección de una tabla que contenga los valores de escore, digestibilidad y PDCAAS de alimentos constituye un aporte de utilidad cuando se desea seleccionar alimentos en un plan de alimentación en función de su calidad proteica.<br>The protein score reflects its amino acids (AA) content in comparison with the ideal protein. However, when there is a need to know the use of AA by the organism it is necessary to do a correction of the score value by protein digestibility (PDCAAS). Since this information is not available for usually con-sumed foods, the present work aimed at calculating the PDCAAS values of these foods. The score was calculated the limiting AA of 70 foods, taking as reference protein the AA pattern for children > 1 year old and adults proposed by the U.S. National Academy of Sciences for the year 2002. The PDCAAS value was obtained in each case by multiplying the score value by the digestibility index. For vegetable foods the obtained score values and PDCAAS were, respectively: vegetables 88.5% / 73.4%, tubercles 89.44% / 74.24%, fresh fruits 75.6% / 64.3%, dried fruits 65.6% / 48.1%, legumes in general 89.2% / 69.58%, chickpea and soybean 100% / 78%, cereals and derivatives 68.8% / 58.5%. Creation of table that contents the score values, digestibility values, and PDCAAS of foods is a useful tool when food selection for a dietary plan based on its protein quality is desirable.

To underline the importance of protein quality in plant-based diets, we estimated the protein quality of different exclusively plant-protein-based day menus that are based on the &ldquo:planetary health diet&rdquo: developed by the EAT-Lancet Commission. PDCAAS and DIAAS were used to estimate the protein quality (PQ) and fulfilling of the amino acid recommendation for adults in vegan daily menus based on the planetary health diet: 2 days with only low-quality (LQ) protein sources and 2 days with low + high-quality (HQ) protein sources. The protein quality of Day 1LQ (DIAAS 76, PDCAAS 88) was increased by the addition of high-quality protein sources (HQPS): Day 1HQ (DIAAS 94, PDCAAS 98). Day 2LQ had a low PQ (DIAAS 71, PDCAAS 74), but when HQPS were used (Day 2HQ), the PQ increased (DIAAS 83, PDCAAS 88). Scenarios (day 1HQ, day 1LQ, and day 2 HQ) were classified as of good PQ. However, day 1LQ had a low protein quality. Consuming HQPS in a vegan diet can help to fulfil the recommendation of essential amino acids. This work served to understand and apply methods to estimate protein quality that can be applied to optimize protein mixtures to fulfil amino acid requirements in the future.