Safflower Protein Isolates: Influence of Recovery Conditions Upon Composition, Yield and Protein Quality

Safflower protein isolates (SPI) containing from 86.7–95.6% protein (N × 5.3) were prepared by extracting safflower meal at pH 8, 9 or 10 with NaOH and precipitating the protein with HCl at pH 5 (the iso‐electric point) or 6. Within the various conditions used, N extraction was 64–77% with N recovered in the SPI ranging between 53 and 64%. Yield, as % weight or % N, increased with more alkaline extraction, whereas SPI with higher protein values resulted from lower extraction pH and precipitation at pH 6. Within any extraction pH, % N recovered was not significantly influenced by precipitation pH. Lysine was the first limiting amino acid in both safflower meal and SPI. True N digestibility of SPI was 96–97%, with that of the meal ranging from 78–85%. PER of safflower meal was not adversely affected by processing temperatures of up to 110°C, and, when combined with soy flour (1:1, w/w), PER was equivalent to that of soy protein alone. PER of SPI (1.05–1.28) was increased to 2.1–2.2 by supplementation with L‐lysine or when combined with a digestible protein with a complementary amino acid composition, such as rice bran protein concentrate.