Extracting Phenolic Compounds from Products of Mechanically Fractionated Sunflower Meal

Sunflower is an oilseed crop of global significance. It is a valuable source of protein with a crude protein content of up to 40%. Mechanical fractionation increases the yield of crude protein content from plant raw materials, but it remains understudied for sunflower meal. Sunflower meal contains up to 4% phenolics, which renders it with strong antioxidant properties. However, phenolics may cause coloration. This article describes sunflower protein preparations with low phenolic content. The study featured sunflower meal fractions obtained by mechanical fractionation with high crude protein content. To reduce the phenolic content, the fractions were treated with ethyl solutions. The antioxidant properties of the resulting protein preparations were determined using the DPPH radical scavenging method. The phenolic content of sunflower meal fractionation products ranged from 2.81 to 3.31% and correlated with the crude protein content (41.98–43.87%). Fractions with the same particle size (≤ 0.25 mm) had similar crude protein and phenolic contents, regardless of the original sample composition and the grinding method. The obtained fractions demonstrated enhanced antioxidant properties (51.08–54.52% DPPH). The highest phenolic yield (73%) belonged to the procedure that involved a single extraction with 80% ethanol at 60°C and a hydromodulus of 1:10. This result was comparable to the yield (76%) obtained by three extractions. The resulting protein preparations were rich in crude protein but low in phenolics. The method could be used to fortify flour products with proteins and antioxidants.