Simplified process of extraction of polyphenols from agroindustrial grape waste

Abstract The extraction, and stability of polyphenols from the grape residue were studied. The extractions were performed following the Box-Behnken design, and the surface response methodology was used to model the extraction of total anthocyanins (TA), flavonols (TF), and phenolics (TP). The extraction was optimized simultaneously by the desirability function. The degradation kinetics of monomeric anthocyanins, and the increase in polymeric color were modeled under refrigeration conditions. The extraction with a temperature of 60 °C, solid:liquid ratio of 1/25 g/mL, and time of 80 min, maximized the recovery of TA (30.96 mg/100 g), TF (73.34 mg/100 g), and TP (856.78 mg EAG/100 g). The degradation of monomeric anthocyanins, and the increase in polymeric color followed a kinetic first-order reaction, with reaction rates (k) of 4.10 x 10-3 days-1, and 3.46 x 10-3 days-1, respectively. The half-life (t1/2) of anthocyanins was 169 days. The ethanol-citric acid solution allowed polyphenols to be efficiently extracted from the grape residue, and had a positive effect on the stability of anthocyanins.

摘要 本研究针对葡萄残渣中多酚类物质的提取工艺及其稳定性展开系统研究。采用Box-Behnken设计（Box-Behnken design）完成提取实验，并通过响应面法（surface response methodology）对总花青素（total anthocyanins, TA）、黄酮醇（flavonols, TF）及总酚（phenolics, TP）的提取过程进行建模。借助合意函数（desirability function）实现多指标同步优化提取方案。在冷藏条件下，对单体花青素的降解动力学以及聚合色的增幅进行建模分析。当提取温度为60℃、固液比为1/25 g/mL、提取时长为80 min时，总花青素、黄酮醇与总酚的提取回收率达到最优水平，分别为30.96 mg/100 g、73.34 mg/100 g及856.78 mg EAG/100 g。单体花青素的降解反应与聚合色的提升均遵循一级动力学反应规律，其反应速率常数（k）分别为4.10×10⁻³ 天⁻¹与3.46×10⁻³ 天⁻¹。花青素的半衰期（t₁/₂）为169天。乙醇-柠檬酸溶液可高效从葡萄残渣中提取多酚类物质，且对花青素的稳定性具有积极的改善作用。