Influence of steeping conditions (time, temperature, and particle size) on antioxidant properties and sensory attributes of some white and green teas

Abstract

The influence of commonly used steeping times and temperatures, as well as leaf size on the antioxidant activity and sensory attributes of tea were studied. Five unblended white and green tea samples from China and Malawi, infused in hot (70 °C and 90 °C; 7 min) or cold water (room temperature: 15, 30, 60, or 120 min) either as whole leaves or as milled, were analyzed. Total phenolic and flavonoid contents as well as antioxidant power (ABTS assay) were measured. The results show that the maximum extraction efficiency occurs with cold water for 120 min and with hot water at 90 °C and that only in the case of teas from whole, large leaves, the extraction was greater in cold than in hot infusions. Moreover, tea infusions prepared from milled leaves have the greatest antioxidant activity. In the sensory evaluation of some of the tea infusions, white teas were perceived more fragrant than green ones and were judged as the most favorite by the majority of the judges, especially for the brew prepared in cold water from whole leaves; all infusions obtained from the milled leaves in fact have a more bitter and astringent taste.

• Antioxidant activity
• flavonoid
• tea extract
• sensory evaluation
• total phenolic content

Acknowledgements

The authors express their gratitude to Alexander Kay of Satemwa Tea Estates, Thyolo (Malawi) for supplying African teas and to Fabiola Ruggero of “Cose di Tè”, Jesi (Italy) for supplying the Chinese teas.

Declaration of interest

The authors declare that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. Authors confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. The authors thank the Polytechnic University of the Marche for financial support.