Enhancing functionality and colour profile in sunflower protein isolates through sustainable protein extraction technologies: Adding value to commercial sunflower meal

Abstract: The rise in protein demand pushes the need to develop new plant protein ingredients using sustainable technologies to replace traditional proteins. Sunflower is a widely cultivated oilseed and processing results in a defatted sunflower meal (SFM) by-product with 30-40% protein content (DWB). The objective is to investigate the production of sunflower protein isolates (SFPI) from commercial SFM using three sustainable and novel extraction technologies: divalent salt-based (DV-SFPI), monovalent salt-based (MV-SFPI), and deep eutectic solvent extraction (DES-SFPI) with improved performance and functionality. The performance, techno-functional, and structural properties of extracted SFPI were compared to the industrial-standard alkaline extracted SFPI (ALK-SFPI) to determine their potential applications. Data is analyzed with ANOVA followed by Tukey’s test (n=3), with significant difference at p < 0.05. The protein purity of MV-SFPI, DV-SFPI, and DES-SFPI of 90.18 ± 0.48%, 90.06 ± 1.01%, and 88.46 ± 1.38%, respectively, are significantly higher than Alkaline-SFPI with 69.35 ± 0.49%. Compared to ALK-SFPI, the protein yield and extraction recovery rate were significantly improved and highest for DES-SFPI (56.92 ± 0.61% and 24.73 ± 0.50%) and MV-SFPI (54.12 ± 1.15% and 23.56 ± 0.78%), followed by DV-SFPI (45.27 ± 1.80% and 19.67 ± 0.29%). Furthermore, divalent and monovalent salt-based extractions effectively reduced the fat content of SFPI to 6%, compared to the initial 15% present in SFM. While the water holding capacity was decreased for all SFPI samples compared to ALK-SFPI, the oil holding capacity was significantly improved for DES-SFPI and DV-SFPI to 1.62 ± 0.01 and 1.48 ± 0.02 (g oil/g protein), respectively, compared to 1.30 ± 0.01 (g oil/g protein) for ALK-SFPI. Lastly, DV-SFPI had an enhanced colour with the highest L* value of 84.07 ± 0.23, due to the exclusion of green chlorogenic acid present in ALK-SFPI. The novel extraction methods have potential in adding value to SFM.