December 06, 2011 08:30 ET

Protein Quality Evaluation Method Supports Soy

Evaluation Method Supports Soy Protein as a Quality Protein Comparable to Meat, Eggs and Dairy

ST. LOUIS, MO--(Marketwire - Dec 6, 2011) - The importance of protein in the human body is indisputable; however, the idea of what makes a protein a "quality protein" has not been as well-understood. A new study from the Journal of Agriculture and Food Chemistry takes a closer look at the criteria for determining the quality of a protein. Traditional methods for determining protein quality have shown most plant proteins, such as pea protein, are lower in quality than animal-based proteins.

The Food and Agriculture Organization (FAO) and the World Health Organization (WHO) recommend the protein digestibility-corrected amino acid score (PDCAAS) as a simple and scientific procedure for assessing protein quality. The PDCAAS methodology focuses on three different parameters: the amount of each essential amino acid the protein contains, how easily the protein can be digested and by taking both of those parameters into account, whether the protein meets the FAO/WHO's amino acid requirements set for children aged 2 to 5 years, as they have higher needs to support growth and development than adults.

"Accurate methods for determining protein quality are key to helping people plan a healthful diet," said Glenna Hughes, MS, research scientist at Solae. "Due to the increasing interest in including plant-based proteins in the diet, accurate information on protein quality is needed in the literature to demonstrate that a diet can include quality plant-based proteins."

This study investigated four different food products at two laboratories and discovered lab-to-lab variations in the amino acid analysis. Senior scientist, David Ryan, MS looked to uncover a correction factor that could explain differences in PDCAAS values between laboratories. The experiment concluded that PDCAAS determinations should take nitrogen recovery into account to correct for analytical method error.

Even though literature values and official methodology often cite nitrogen recovery, it also is helpful to have a repeatable history of amino acid recovery values on similar products or ingredients from a validated laboratory for comparison. Solae, LLC and its legacy companies have a long history of testing protein quality of soy protein isolates and concentrates, which provided a context for the current analysis completed with the two different labs. Nitrogen recovery comparison can be a useful tool in selecting a lab for amino acid analysis. Data generated in this study indicated that of the four ingredients evaluated, three different Solae isolated soy proteins and one Solae soy protein concentrate have a PDCAAS of 1.00, supporting the position of soy protein as a high-quality protein, similar to meat, egg and dairy proteins.

For more information on the study, the following is a link to the abstract:

Solae, LLC is a world leader in developing soy-based ingredients for nutritious, great-tasting products. Solae provides solutions that deliver a unique combination of functional, nutritional, economical and sustainable benefits to our customers. Headquartered in St. Louis, Mo., USA, the company was formed through a joint venture between DuPont (NYSE: DD) and Bunge (NYSE: BG) in 2003. Solae is a recipient of 2011 Ethisphere's Ethics Inside Certification and was recognized as one of 100 "World's Most Ethical Companies" in 2011. For more information, visit, or follow the company on Twitter at, Facebook at, and LinkedIn at

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