Use of response surface methodology in optimization of phenolic compounds extraction from the shell of Hymenaea courbaril L. (Jatobá) fruits

Abstract The food and medicinal habits of Amazon people are rich in fruits considered as exotic or commercially underutilized, some of which generate a considerable amount of residue. The Hymenaea courbaril L. (Jatobá) fruit shell was submitted to a simultaneous extraction of total phenolic compounds, optimized by response surface methodology. Preliminary experiments, investigating sample-solvent ratio (g/mL), time (minutes) and extraction temperature (ºC), indicate the limits for experimental region design, which was monitored by rotational central composite design consisting of 19 runs. The experimental results fitted well to the second order polynomial model generated, which was able to significantly describe the observed variability for response variables. The optimized conditions were 60.6% ethanol, 64.18 ° C, 71.93 minutes and the model presented predicted values of 35.265 ± 2.22 mg gallic acid equivalent / g dry matter and 1.210 ± 0.16 mg rutin equivalent / g dry matter, for total phenolic compounds and total flavonoids, respectively. The experimental observed values, 33.234 ± 1.66 mg gallic acid equivalent / g dry mater and 1.216 ± 0.008 mg rutin equivalent / g dry matter, for total phenolic compounds and total flavonoids respectively, agreed with those predicted within a 95% confidence interval. These results confirm the predictive capacity and the adequacy of response surface methodology in optimizing simultaneous extraction of total phenolic compounds and total flavonoids from shell of jatobá fruits.

摘要 亚马孙地区原住民的饮食与药用传统中，包含诸多被视为异域特色或商业开发不足的果品，其中部分果品会产生大量副产物。本研究以孪叶豆（*Hymenaea courbaril* L.，俗称Jatobá）的果壳为材料，采用响应面法（response surface methodology）优化总酚类物质的同步提取工艺。前期实验考察了料液比（g/mL）、提取时间（min）与提取温度（℃），以此确定实验区域的参数范围，并通过包含19个实验组的旋转中心复合设计（rotational central composite design）开展实验布局。实验结果与构建的二阶多项式模型拟合度良好，该模型可有效描述响应变量的观测变异情况。优化后的工艺条件为：乙醇体积分数60.6%、提取温度64.18℃、提取时间71.93 min；模型预测总酚类物质与总黄酮类物质的得率分别为35.265±2.22 mg没食子酸当量（gallic acid equivalent）/g干物质、1.210±0.16 mg芦丁当量（rutin equivalent）/g干物质。实验实测值分别为33.234±1.66 mg没食子酸当量/g干物质与1.216±0.008 mg芦丁当量/g干物质，在95%置信区间内与预测值相符。上述结果证实了响应面法用于优化孪叶豆果壳总酚类与总黄酮类物质同步提取工艺的预测能力与适用性。