The aim of this work is the optimization of phenolic compound extraction from three by-products of banana crops (rachis, discarded banana, and banana’s pseudostem pulp), as a way to valorize them through a green extraction process. The influence of the temperature and aqueous ethanol concentration (Et-OH) on extract properties (total phenol content (TPC) and antioxidant activity) was firstly analyzed. 78 ℃ and ethanol concentrations close to 50% yielded the best results for the three materials. The equations obtained by the response surface methodology gave a satisfactory description of the experimental data, allowing optimizing the extraction conditions. Under optimized conditions, time influence was then assessed, although this parameter seemed not influence results. Among the three by-products, rachis extract (60% Et-OH, 78 ℃, and 30 min) presented the highest TPC (796 mg gallic acid/100 g of dried material) and antioxidant activity (6.51 mg Trolox equivalents/g of dried material), followed by discarded banana, and pseudostem pulp. Under the optimal conditions, experiments were performed at a larger scale, allowing to determine the extraction yields (EY) and to characterize the extracts. The highest EY was obtained for the rachis (26%), but the extract with the highest activity was obtained for discarded banana (50% Et-OH, 78 ℃, and 60 min), which presented a TPC of 27.26 mg/g extract corresponding to 54.59 mg Trolox equivalents/g extract. This study contributes to the valorization of banana crops residues as a source of polyphenolic compounds with bioactive functions that can be extracted under economic extraction conditions.

Graphical abstract

中文翻译：

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优化香蕉作物副产品溶剂萃取生产生物活性化合物

这项工作的目的是优化从香蕉作物的三种副产品（轴、丢弃的香蕉和香蕉的假茎果肉）中提取酚类化合物，作为通过绿色提取过程使它们增值的一种方式。首先分析了温度和乙醇水溶液浓度（Et-OH）对提取物性质（总酚含量（TPC）和抗氧化活性）的影响。78 ℃和接近50%的乙醇浓度对三种材料产生了最好的结果。通过响应面方法获得的方程对实验数据给出了令人满意的描述，可以优化提取条件。在优化条件下，然后评估时间影响，尽管该参数似乎不影响结果。三种副产物中，羽轴提取物（60% Et-OH，78 ℃，和 30 分钟）表现出最高的 TPC（796 毫克没食子酸/100 克干材料）和抗氧化活性（6.51 毫克 Trolox 当量/克干材料），其次是丢弃的香蕉和假茎果肉。在最佳条件下，以更大规模进行实验，从而确定提取率 (EY) 并表征提取物。轴的 EY 最高（26%），但活性最高的提取物是废弃的香蕉（50% Et-OH，78 ℃，60 分钟），其 TPC 为 27.26 mg/g对应于 54.59 mg Trolox 当量/g 提取物。这项研究有助于香蕉作物残留物作为具有生物活性功能的多酚化合物的来源，可以在经济提取条件下提取。

图形概要