Résumé
Tectona grandis leaf extracts obtained at pilot scale processes (ultrasound-assisted extraction, cross-flow microfiltration, reverse osmosis concentration) contains phenolic compounds that exhibit antioxidant properties. The final reverse osmosis concentrate extract presented higher content of polyphenol (21,080 +/- 117 mol g(-1) GAE) and antioxidant capacity (8490 +/- 29 mol g(-1) TE) comparatively to crude extract (1300 +/- 12 mol g(-1) GAE for polyphenol and 430 +/- 2 mol g(-1) TE for antioxidant activity) or cross flow micro filtration extract (1170 +/- 10 mol g(-1) GAE for polyphenol and 400 +/- 10 mol g(-1) TE for antioxidant). The concentration factors of polyphenol and antioxidant capacity were 18 and 21, respectively. High-performance liquid chromatography (HPLC) coupled to electrospray ionization mass spectrometry (ESI-MS) detection negative ion mode has been used to identify and characterized polyphenols in the concentrate extract of T. grandis leaves. Seven phenolic acids and flavonoids were characterized. Verbascoside (phenolic acid) was described as the most abundant phenolic compounds in this concentrate extract. Two drying technologies (freeze-drying and spray-drying) were used to obtained stable powder from concentrate extract. The effect of these drying technologies on phenolic compounds and antioxidant activity were studied. Freeze-drying presented a good recovery of phenolic compounds and antioxidant capacity. This drying technology could be used for preservation of T. grandis extract.