Evaluation of extraction technologies and optimization of microwave and ultrasonic assisted consecutive extraction of phenolic antioxidants from winery byproducts

摘要

Acid, enzyme, ultrasonic, and microwave were used to assist extraction of polyphenols in grape pomace, skins, and seeds. The relationship among extraction technologies, polyphenolic content and antioxidant capacities was analyzed by principal component analysis (PCA), and the effective extraction condition for specific target was optimized by response surface methodology. Polyphenolic content could be mostly enhanced by microwave-assisted processing, while PCA showed that ultrasound-assisted processing had a more positive effect on the antioxidant activity of extracts. Microwave and ultrasonic assisted consecutive extraction on Merlot seed showed the superiority and the numerical optimization for the highest global desirability value of antioxidants extraction was obtained at the condition of 1:24.50 (liquid-solid ratio), 68.00% EtOH, 3.24 min (microwave time) and 60.00 min (sonication time) with desirability of 0.973. The predicted extraction condition of total phenolics, total flavonoids, and proanthocyanidins were 19.51 mg GAE/g DW, 29.06 mg RE/g DW, and 24.47 mg CE/g DW, respectively; while the values for antioxidant activity were 87.25% hydroxyl radicals-scavenging activity, 83.39% superoxide radical-scavenging activity, and 1.86 (at 700 nm) reducing power. Practical applications Polyphenols present an important antioxidant activity and health-beneficial properties. Sustainable and relatively cheap raw material should be utilized in the production, such as winery byproducts. However, microwave-assisted processing may affect the antioxidant activity of extracts despite that the polyphenolic content could be enhanced. This research provides information about optimization of novel extraction technique (microwave and ultrasonic assisted consecutive extraction), which could be successfully used for polyphenols extraction due to increased yield of target compounds and improved quality of the liquid extracts in terms of antioxidant activity. These findings are a useful tool for producers of winery byproducts to achieve an effective and economically viable extraction process as well as optimal composition and bioactivity in terms of antioxidant capacity.