Calculation of Amino Acid Scores for Different Food Proteins

The method for evaluating the relative nutritional quality of different protein sources that is used in this report is based on calculating the protein digestibility corrected amino acid score (PDCAAS) as proposed by FAO/WHO (1991). It is calculated as follows:

PROTEIN AND AMINO ACIDS 689

TABLE 10-26 Summary FNB/IOM 2002 Amino Acid Scoring Pattern for Use in Children > 1 Year of Age and in All Other Older Age Groups

Amino Acid

mg/g proteina

mg/g N

Histidine

18

114

Isoleucine

25

156

Leucine

55

341

Lysine

51

320

Methionine + cysteine

25

156

Phenylalanine + tyrosine

47

291

Threonine

27

170

Tryptophan

7

43

Valine

32

199

a Protein = nitrogen X 6.25.

a Protein = nitrogen X 6.25.

[mg of limiting amino acid in 1-g test protein]

mg of same amino acid in 1-g reference protein

As mentioned earlier, in comparing the amino acid reference (or scoring) patterns (Table 10-24) for 1- through 3-year-old children and the adult age groups, it would be hard to justify proposing separate amino acid scoring patterns for these populations for practical purposes. Therefore, for calculation of the amino acid score, corrected for digestibility (PDCAAS, %), it is recommended that one scoring pattern be used to cover all ages from 1 year and above, as shown in Table 10-26.

A number of examples of the PDCAAS for different food proteins or diets based on three major protein sources are given in Table 10-27. As shown, wheat (lysine limiting) and chickpea proteins (sulfur amino acid limiting) have a PDCAAS of 44 and 87 percent, respectively. For a diet based on a mixture of wheat, chickpea, and skim milk proteins the PDCAAS is 110 percent, which is truncated to a value of 100, since the relative efficiency of utilization of the limiting amino acid cannot be greater than that of the amino acid scoring pattern at nitrogen intakes sufficient to meet nitrogen needs. Finally, it should be noted that PDCAAS scores have only been calculated here based on four indispensable amino acids (lysine, sulfur amino acids, threonine, and tryptophan). These are

690 DIETARY REFERENCE INTAKES

TABLE 10-27 Calculation of PDCAASa for Selected Individual Food Proteins and for a Mixture of These Proteins, Based on the FNB/IOM 2002 Amino Acid Scoring Pattern

Amino Acid Content (mg/g protein) b

- Protein

Protein Lys SAA Thr Trp Digestibility PDCAAS (%)

Wheat

25

35

30

11

0.85

Chickpea

70

25

42

13

0.80

Milk powder

80

30

37

12

0.95

Mixture (% of protein) Wheat (19) Chickpea (32) Milk powder (49) For combinatione

Mixture (% of protein) Wheat (19) Chickpea (32) Milk powder (49) For combinatione

29 37

0.88

a Data for proteins taken from Table 10 of FAO/WHO (1991) using the procedure described therein to determine PDCAAS (Protein Digestibility Corrected Amino Acid Score).

b Lys = lysine; SAA = sulfur amino acids; Thr = threonine; Trp = Tryptophan. c Lysine or sulfur amino acid = limiting amino acid.

d Where relevant, the nontruncated value for the PDCAAS is given prior to truncation to a value of 100.

e Weighted values based on the proportion of the total protein in the mixture that is contributed by each protein source.

the most likely limiting amino acids in common food protein sources and so have been considered here for illustrative purposes.

There have been discussions on ways to improve the PDCAAS procedure and further developments in this context are needed. Until better methods are developed, the foregoing procedure is recommended, using the digestibility values proposed by FAO/WHO (1991).

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  • Emily
    What is amino acid score?
    2 years ago
  • ermenegildo
    How to calculate amino acid scores?
    2 years ago
  • NINA
    How to calculate amino acid score?
    2 years ago
  • cari
    What is amino acid scoring pattern?
    1 year ago
  • jere
    How to calculate pdcaas score?
    1 year ago
  • Aleisha
    How to figure out which amino acids are in a food?
    1 year ago
  • REZENE
    How to calculate pdcaas with two pdcass scores?
    1 year ago
  • odo
    How to calculate limiting amino acids?
    1 year ago
  • katja
    How to calculate the protein completeness score?
    11 months ago
  • sadoc
    How to calculate limiting amino acid?
    11 months ago
  • francesco
    How to determine the limiting amino acid in a protein?
    11 months ago
  • brenton taylor
    What is the meaning of amino acid score?
    10 months ago
  • leigh
    How to calculate pdcaa?
    9 months ago
  • LOTHO
    How to work out amino acid score from amino acid content and amino aacid socring pattern?
    7 months ago
  • yohannes
    How concentraction of aminohow to determine the concentration of amino acid?
    7 months ago
  • artemio calabrese
    How to calculate an amino acid score based on the amino acid profile?
    7 months ago
  • Giona Schiavone
    What is full amino acid score protein?
    5 months ago
  • James
    How to calculate the pdcaas in protein with ideal ratio?
    3 months ago
  • liisa kalliala
    How to calculate relative proportions of charged amino acids?
    2 months ago
  • minnie
    What is a figure of an amino acid of a protein?
    20 days ago

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