Effects of temperature and time on polyphenolic content and antioxidant activity in the pressurized hot water extraction of deodorized thyme ( Thymus vulgaris ). http://dx.doi.org/10.1021/jf3027759Revista : Journal of Agricultural and Food Chemistry
Volumen : 60
Número : 44
Páginas : 10920-10929
Tipo de publicación : ISI Ir a publicación
The effects of temperature (50 − 200 ° C) and contact time (5 − 30 min) on the pressurized hot water extraction of deodorized thyme were explored for antioxidant activity, polyphenol pro ﬁ les, and total antioxidants. Six not previously reported polyphenolic compounds were identi ﬁ ed in thyme. An inverse correlation was found between the antioxidant activity and totalantioxidants with the amount and diversity of polyphenols. The highest total extract yield and antioxidant activity were obtained at 200 ° C, although maximum polyphenol extraction yields of hydroxycinnamic acids, ﬂ avones, ﬂ avonols/ ﬂ avanones, and total polyphenols were detected at 100 ° C and 5 min. Higher temperatures and longer exposure times reduced extract polyphenoldiversity. Dihydroxyphenyllactic acid was the only phenolic compound for which extraction yield increased with temperature, probably as a product of the thermal degradation of rosmarinic acid. Consequently, for extracting phenolics from thyme, 100 ° C and 5 min would be appropriate operating conditions, whereas antioxidant-active nonphenolic compounds were favored at highertemperatures and exposure times.