Integrated sunflower-based biorefinery for the production of antioxidants, protein isolate and poly(3-hydroxybutyrate)

Sunflower meal (SFM) has been used for the production of an antioxidant-rich fraction, protein isolate and nutrient-rich fermentation supplements. Suspension of SFM in water led to the production of a lignocellulose-rich fraction and a protein concentrate fraction. The ethanolic extract from the SFM showed high antioxidant activity, as it was measured by the DPPH (1,1-diphenyl-2-picrylhydrazyl radical) method. The extract obtained from the SFM contained mainly chlorogenic acid (214.3 mg/100 g on a dry basis) and gentisic acid (153.76 mg/100 g on a dry basis) as was quantified by HPLC-DAD analysis. The antioxidant-free protein concentrate fraction was used for the production of protein isolate (purity higher than 95% w/w) after alkaline treatment followed by acidic precipitation at the isoelectric point. Remaining solid and liquid streams were used for the production of nutrient-rich hydrolysates based on on-site enzyme production for hydrolysis of residual streams. Crude glycerol and nutrient-rich hydrolysates were used in fed-batch bioreactor fermentations for the production of 57 g L−1 of poly(3-hydroxybutyrate) (PHB) with an intracellular content of 86.2% (w/w). This is the first study that reports the utilization of biodiesel industry by-products for the production of value-added co-products and PHB with no supplementation of commercial nutrient supplements.