San Juan is a leading pistachio producer in Argentina. Pistachio industrial processing generates biowastes that can be reused. These biowastes can be used as a precursor of bioactive components of interest as the phenolic compounds. Therefore, the aim of this work is to optimize the conditions of stirring extraction (SE) and ultrasonic-assisted extraction (UAE) of phenolic compounds (PC) using response surface methodology (RSM). A central composite design (CCD) was used to analyze the effects of the independent variables: ethanol:water ratio and extraction time. The optimal conditions for extraction of phenolic compounds from pistachio industry biowaste through UAE method were a volumetric ratio of ethanol:water ratio about 0.5 and an extraction time between 0.7 and 0.94 h. For SE, the optimal conditions were a volumetric ratio of ethanol:water ratio about 0.6 and an extraction time between 2 and 2.7 h. Longer period of extraction, for both extractions UAE and SE, produces degradation reactions and therefore a radical capture activity loss. SE had optimal values of volumetric proportion solvents comparable with those corresponding to UAE. But SE requires more time to produce breaks in the cell, and dissolution and diffusion of bioactive compounds in the extracts.

Graphical abstract

San Juan是阿根廷领先的开心果生产商。开心果工业加工过程中会产生可再利用的生物废物。这些生物废料可用作感兴趣的生物活性组分作为酚类化合物的前体。因此，这项工作的目的是使用响应表面方法（RSM）优化酚类化合物（PC）的搅拌萃取（SE）和超声辅助萃取（UAE）的条件。使用中央复合设计（CCD）分析以下自变量的影响：乙醇：水的比例和提取时间。通过阿联酋方法从开心果工业生物废料中提取酚类化合物的最佳条件是乙醇：水的体积比约为0.5，提取时间为0.7至0.94 h。对于SE，最佳条件是乙醇的体积比：水比约为0.6，萃取时间为2至2.7 h。对于UAE和SE萃取，萃取时间较长，会产生降解反应，因此会导致自由基捕获活性损失。SE具有与阿联酋相对应的最佳体积比例溶剂值。但是SE需要更多的时间在细胞中产生断裂，以及提取物中生物活性化合物的溶解和扩散。

图形概要