Sometimes the tipping point in the development of a truly great product involves a quick insight from a research chef. At other times, however, that make-or-break formulation moment occurs when a food scientist sits down at a computer and calculates the exact types and levels of various protein ingredients needed in order reach a desired % Daily Value (% DV) for a product's Nutrition Facts Panel. The optimal approach is to not simply add more proteins, but to figure out which proteins to choose in order to have the greatest impact on increasing a food's % DV.
At the 2013 Protein Trends & Technologies Seminar held April 10 in Arlington Heights, Ill., Scott Martling, group leader, R&D, International Food Network, provided an explanation on how to maximize a food's PDCAAS value (Protein Digestibility Corrected Amino Acid Score). In a presentation titled "Using Protein-Rich Components to Achieve Desired Labeling," Martling reminded the audience that while foods are allowed to list grams of protein per serving on Nutrition Facts Panels, the % DV can only be listed if the quality of the proteins present is known.
Additionally, the % DV of a food must be known before a protein content claim is made. In the U.S., one qualification for a "Good Source of Protein" claim is that a food contains 10-19 percent DV per serving. An "Excellent Source" claim can be made when 20 percent or more DV of protein is present. For products targeting older children and adults, the quality of protein in a food is determined by its PDCAAS.
A PDCAAS quantifies a protein's quality based on human amino acid requirements and their ability to digest a protein. According to Gertjan Schaafsma, "The method is based on comparison of the concentration of the first limiting essential amino acid in the test protein with the concentration of that amino acid in a reference (scoring) pattern."
The PDCAAS's of various proteins can be found on many websites and from protein ingredients suppliers. While there have been minor inconsistencies and corrections over time, generally casein and whey, soy and egg are considered to have PDCAAS scores of 1.00 while those of tree nuts are a bit under .50 and wheat gluten even lower.
The importance of the concept of a "limiting essential amino acid" is demonstrated with gelatin and isolated tryptophan, an essential amino acid. Gelatin contains almost no tryptophan and thus has a PDCAAS of zero. So too would tryptophan by itself since it lacks other essential amino acids. The addition of even small amounts of tryptophan to gelatin would significantly increase the PDCAAS of a gelatin/tryptophan combination.
That is the heart of Martling's formulation advice. Working with information from a Pulse Canada web page, he gave the example of a 55g serving of durum wheat pasta with a protein content of 11.7 percent and a PDCAAS of 0.43. Multiplying 55g times 0.117 results in 6.4g protein per serving (or Reference Amount). Since the PDCAAS of that protein is only 0.43, the 6.4g protein is multiplied by 0.43 to equal 2.8g of complete protein in a serving of pasta. The daily value (DV) for protein is set at 50g.
To make a claim of a "Good Source of Protein," at least 10 percent of the DV must be met or 5.0g (10 percent 0f 50g). The 2.8g complete protein is thus less than the 5.0g needed for a claim of a "Good Source of Protein" and it cannot be made.
Lentils efficiently contribute essential amino acids that are limiting in wheat proteins. Formulating a 25:75 lentil/durum wheat flour blend results in pasta with 14.7g protein per serving and a PDCAAS value of 0.71. Rerunning the calculations as follows: 55g serving times 0.147 protein equals 8.1g protein per serving; Multiplying 8.1g by 0.71 gives 5.7g complete protein, which is happily higher than the minimal 5.0g needed for a "Good Source" claim.
Martling commented that although the calculations may be confusing initially, they become second nature once repeated few times. For more help, download Martling's presentation.
Protein PDCAAS and DIAAS values will be discussed at the 2014 Protein Trends & Technologies Seminar next April 8-9.