Valorization of grape winery waste: optimization of drying conditions for bioactive compounds extraction
摘要
Valorization of grape waste, a by-product of the winery industry, has gained attention recently as it can help reduce environmental impact while adding value to the winemaking process by recovering a range of biologically active compounds. In the present study, the effects of different drying methods on the extraction and stability of bioactive compounds from grape winery waste were investigated. Four drying methods—tray drying (55 ± 2 °C for 16 h), shade drying (28 ± 2 °C for 72 h), vacuum drying (60 ± 2 °C for 3 h), and direct sun drying (for 18 h)—were applied to grape waste of cv. Punjab MACS Purple, and the bioactive compounds were analyzed. Further, the most effective method, vacuum drying, was optimized with respect to operating conditions to maximize the extraction of bioactive compounds for its potential use in the development of functional foods. Bioactive compounds—including total phenols, flavonoids and anthocyanins were extracted and quantified using HPLC and GC-MS. Vacuum drying at 60 °C for 3 h showed the highest retention of all bioactive compounds i.e. 5940 mg/100 mL anthocyanins, 2900 mg/100 mL flavonoids, and 7900 mg/100 mL phenolics, along with 2.22% RSA antioxidant activity followed by tray drying, shade drying, and direct sun drying. This study demonstrates that grape winery waste dried by the vacuum drying method offers an attractive alternative for valorizing this by-product, maintaining high levels of bioactive compounds, and providing scalable, economically viable solutions for the winery industry.