Dissertação
Estudo do poder antioxidante em infusões de ervas utilizadas como chás
Fecha
2013-03-28Registro en:
ABREU, Luciana de. STUDY OF ANTIOXIDANT POWER IN HERBAL INFUSIONS USED AS
TEA. 2013. 88 f. Dissertação (Mestrado em Ciência e Tecnologia dos Alimentos) - Universidade Federal de Santa Maria, Santa Maria, 2013.
Autor
Abreu, Luciana de
Institución
Resumen
Tea is one of the oldest and most consumed beverages in the world, being
mentioned as one of the best sources of phenolic compounds. These substances
have been studied especially because they have antioxidant activity. The term refers
to tea product herbal infusions the genus Camellia sp. Being that variations in their
designations are relative to the type of process that these plants suffer. Antioxidants
are substances used to preserve food through the retardation of deterioration,
rancidity and discoloration resulting from autoxidation, while biological systems that
protect against the damaging effects of reactions of reactive oxygen species. Various
methods are used to determine the antioxidant activity of extracts and compounds
isolated. One of the most widely used is to evaluate the scavenging activity of the
stable free radical DPPH (1,1-diphenyl-2-picryl-hydrazyl). Other methodologies used
to evaluate the antioxidant capacity of an extract are the determination of total
phenolic compounds, total polyphenol content, and iron reduction technique. In this
context, the objective of this study was to determine the content of bioactive
compounds, characterized by its value of antioxidant activity, flavonoids and phenolic
compounds in different types of tea come from the Camellia sinensis plant, namely:
green tea, black tea, white tea, yellow tea and red tea. The experiment was
conducted in the post harvest fruit core research, located in the Department of Plant
Science, Federal University of Santa Maria, RS. The samples were extracted by
infusion sachets of filter paper containing 3 g of the plant in 200 ml of distilled and deionized water by 10 minutes of infusion, at 85 °C. After extraction
the samples were placed in glass containers protected from light and stored at a
temperature of 0.5 °C. Determination of antioxidant activity by DPPH method was
performed by evaluation of polyphenols and flavonoids (colorimetric method), and the
chelating activity of Fe+2. As a result, white tea showed the highest antioxidant
activity among teas evaluated considering the kidnapping of DPPH. This tea also
showed the highest levels of flavonoids and phenolic compounds. Green tea showed
higher antioxidant activity as measured by the percentage of ferrous ion chelating
activity. Among the 20 types of teas evaluated, hibiscus tea has lowest antioxidant
properties. Among the teas originating from Camellia sinensis, the red tea showed
the lowest values of antioxidant activity, regardless of the method or evaluation
performed, but did not differ from black tea, white and yellow in the percentage of
ferrous ion chelating activity. Considering the results of EC50, ilex tea, bilberry and
gorse showed intermediate antioxidant power in relation to the Camellia sinensis teas
and other teas evaluated in this work.