Comparison of the impact of different extraction methods on polyphenols yields and tannins extracted from Moroccan Acacia mollissima barks

•We aim to value Moroccan bark of Acacia mollissima.•The performance of three conventional techniques, maceration at room temperature, infusion and microwave assisted extraction (MAE), on the yield extracts was investigated.•The polyphenols content, condensed tannins and hydrolysable tannins were quantified.•The efficiency of conventional techniques was evaluated by colorimetric assays.•A. mollissima barks, from Morocco are rich in condensed tannins of proantocyanidins types.•Optimum conditions for maceration at room temperature were 20°C, 2h, methanol extraction solvent and ten years age barks.•Optimum conditions for infusion were 60°C, 2h, ethanol extraction solvent and ten years age barks.•Optimum conditions for microwave were 150W, 5min, methanol extraction solvent and ten years age barks.•The choice of extraction method depends on the extractible nature desired (polyphenols, condensed tannins or hydrolysable tannins). The performance of three techniques, conventional maceration at room temperature, infusion and microwave assisted extraction, was evaluated to extract polyphenols, condensed and hydrolysable tannins from Moroccan barks of Acacia mollissima. A comparison of these methods was performed using colorimetric assays. For each technique, the effect of extraction conditions on the yield extracts was evaluated. The variables studied are: solvent nature, barks ages, time extraction, power extraction and heat interaction with solvent nature and barks ages. This study proved that the choice of solvent extraction was a relation of the extraction method used and the extractible nature (polyphenols, condensed or hydrolysable tannins). Methanol was the best solvent to extract tannin and polyphenols using maceration at room temperature, and ethanol was the best for infusion at 60°C. Microwave was more selective to extract polyphenols and tannins under extraction solvent used. Highest polyphenols contents was obtained using methanol. For condensed and hydrolysable tannins, the highest were obtained using water. The polyphenols contents extracted using maceration was closed to the yield obtained with microwave, 354mgGAE/g bark, 442mgGAE/g bark, respectively. This study proved the pertinence of traditional methods to extract polyphenols and tannins compared to the new extraction method (microwave). The best polyphenols yields, condensed and hydrolysable tannins were obtained by microwave followed by the yield obtained by maceration and finally the yield obta