Value-Added Dietary Fiber Concentrate Obtained as Waste after Protein Isolation from Ethanol-Treated Sunflower Meal

Deproteinized sunflower meal (DSM) was obtained as waste from ethanol-treated sunflower meal after alkaline extraction of proteins. The study aimed at biochemically and functionally characterizing the material concerning its potential practical application and valuability. The DSM consisted mainly of proteins (19.88%) and dietary fibers (61.06%) the majority of which were insoluble (53.09%). Cellulose (30.87%) and lignin (21.79%) were the most contributing compounds to the total amount of dietary fibers. The DSM contained Fe (133.29 mg/kg), Zn (201.56 mg/kg), and Cu (31.87 mg/kg). The analyses defined the DSM as a fiber concentrate with relatively high thermal stability. The distraction of the material began at 170°С with a maximum speed at 277°С. The highest water absorption capacity (WAC) of the DSM was observed at pH 6 and 7 (approximately 8 g H₂O/g sample) under all studied conditions including pH from 3 to 10 and three levels of NaCl concentrations (0.00 M, 0.03 M, and 0.25 M). At pH 7, increasing temperature from 20°C to 60°C increased the WAC of the DSM from 8.13 g H₂O/g sample to 9.80 g H₂O/g sample, respectively. Further increase in the temperature diminished the WAC of the DSM. At pH 6, the increase in temperature did not influence positively the WAC of the DSM. The study demonstrated the potential of the DSM, a waste obtained from the protein isolation process, as a valuable ingredient/additive in the food industry.