In Vivo Protein Quality of Pistachios (Pistacia vera L.)

Pistachios (Pistacia vera L.), similar to other nuts, fall under the protein foods category, according to the current U.S. Dietary Guidelines and Canada's Food Guide. When substantiating claims for protein content of pistachios, protein quality data must be available to support these claims. In North America, the Protein Digestibility-Corrected Amino Acid Score (PDCAAS) is used for this purpose, however, Canada requires that this value be used to calculate a Protein Efficiency Ratio (PER). PER can be used for estimating protein quality. The current investigation aimed to offer current assessments of PER and PDCAAS, through the utilization of established in vivo rodent bioassays, for pistachio samples (raw, dry-roasted, and oil-roasted). Amino acid scores established lysine as the most limiting amino acid, with values of 0.933, 1.073, and 1.058 for raw, dry-roasted and oil-roasted pistachios, respectively. PDCAAS values ranged from 83 to 94%, being highest for dry-roasted pistachios. The measured PER values (corrected to casein = 2.50) were 2.53, 2.48, and 2.58 for the raw, dry-roasted, and oil-roasted pistachios, respectively, and were not significantly different from casein. These data support the position that pistachios can be labeled as "good sources of protein" in the U. S. and Canada.