Influence of Cellulase Pretreatment on the Quality Characteristics, Total Phenolic Content, and Antioxidant Capacity of Hydraulic Press-Extracted Grapeseed Oil

Grape seeds, a by-product of winemaking, are a valuable source of oil, rich in essential fatty acids and bioactive compounds. This study evaluated the influence of cellulase pretreatment on the hydraulic press extraction of oil from Vitis labrusca × Vitis vinifera grape seeds. Grape seed powder (GSP) was treated with cellulase at enzyme-to-substrate ratios of 0.5 and 2 g/100 g for 4 h and 18 h. The extracted oils were analyzed for yield, fatty acid composition, total phenolic content, antioxidant capacity, and physicochemical properties. Enzymatic pretreatment significantly enhanced oil recovery compared to the untreated control, with extraction efficiency increasing from 58.21% to 95.05% and oil yield from 6.07 to 9.89 g/100 g GSP. The total phenolic content in oils obtained with cellulase pretreatment ranged from 148.7 to 279.2 mg GAE/kg and was higher compared to 127.5 mg GAE/kg determined in the control oil. Cellulase pretreatment also increased the antioxidant capacity of the oils, particularly in the oil treated at the enzyme-to-substrate ratio of 0.5 g/100 g for 18 h, which showed the highest values in the DPPH and ABTS assays (1.81 and 0.128 mmol TE/kg oil, respectively). The oils maintained a low moisture content (0.47–0.48 g/100 g), a moderate acidity index (2.00–2.89 mg KOH/g), acceptable peroxide values (7.24–11.24 meq O2/kg), and stable density (0.92 g/mL). The fatty acid profile remained unchanged, dominated by linoleic acid (69.8% of total fatty acids). Overall, cellulase pretreatment effectively increased oil yield and improved the chemical and functional quality of grape seed oil without compromising its physicochemical stability.