Improvement of protein extraction from sunflower oil cake using ascorbic acid and N-acetylcysteine: Effects on chemical, structural, and functional properties.

Sunflower oil cake (SFC), a by-product of oil manufacturing, possesses a high protein content but is often disregarded due to its undesirable green color caused by phenolic compounds (PCs) during alkaline extraction. This study aimed at improving the color of extracted sunflower protein concentrate (SPC) without eliminating the PCs by employing two anti-greening additives, ascorbic acid (ASC) and N-acetylcysteine (NAC), at different concentrations (4, 8, and 12 mg/g meal) during extraction. Moreover, the effects of these additives on the chemical, structural, and functional properties of extracted proteins were assessed. The results showed that the SPC extracted without additives (control) and with 4 and 8 mg/g additives exhibited green color, while the most significant greening inhibition was attained with 12 mg/g of either ASC or NAC. All the extraction solutions resulted in SPC with comparable water solubility exceeding 90% and minor variations in the secondary structure, hydrophobicity, and thermal stability of the proteins. All extracted SPCs demonstrated substantial antioxidant activity, adding nutritional benefits to the protein concentrates. In conclusion, incorporating ASC and NAC during the alkaline extraction process proved to be an effective strategy for producing sunflower protein concentrate with improved color and acceptable functional properties. This approach offers the food industry an opportunity to reduce reliance on expensive protein sources, such as soy protein isolates, and paves the way for sustainable utilization of sunflower oil cake as a valuable and versatile protein ingredient in various food applications. [ABSTRACT FROM AUTHOR]