YERBA MATÉ (ILEX PARAGUARIENSIS ST. HIL.): CHEMICAL AND PHYSICAL CHANGES UNDER DIFFERENT AGING CONDITIONS

摘要

The variation of different physicochemical parameters related to yerba matérnquality (caffeine, water extract, total polyphenol content, color parameters andrnantioxidant activity) was studied in yerba maté samples obtained by three differentrnaging methods: (1) natural aging (NA); (2) temperature-controlled agingrn(TCA); and (3) humidity- and temperature-controlled aging (HTCA). Adsorptionrnisotherms at low temperatures (20, 30, 40 and 50C) were also determined. Waterrnextract and color parameters (L and a) increased significantly during aging in thernthree methods studied (P < 0.05). The results also showed that during NA thernpolyphenol content of yerba maté diminished (P < 0.05), while caffeine remainedrnconstant (P > 0.05). The antioxidant activities of yerba maté obtained by NA andrnHTCA were significantly higher (P < 0.05) than the antioxidant activity of yerbarnmaté without aging and the yerba maté obtained by TCA. These variations werernexplained by 0, 1 and 2 kinetic order equations. Kinetic rate constants were higherrnin the HTCA than in the TCA, and these values were higher than in the NArnaccording to temperature decrease. Experimental data of equilibrium moisturerncontent at different temperatures showed good fitting (P < 0.05) with the threernmodels tested (GAB, Halsey and Henderson). No significant differences werernfound either with temperature or with the materials obtained using different agingrnmethods. Although the results obtained demonstrate that different aging methodsrnoriginate similar products, HTCA method is better because it provides a yerbarnmaté with higher total polyphenol content.