Effects of alternative steeping methods on composition, antioxidant property and colour of green, black and oolong tea infusions

Abstract

Cold water steeping is reported to maximise tea health benefits, but requires long infusion time. In this work, the employment of a brief hot infusion step followed by ice addition was evaluated. The comparison of this innovative method with hot and cold steeping was investigated on green, black and oolong teas. Catechins, xanthines and gallic acid content, antioxidant power, total phenolics and colour analysis were evaluated. Hot infusion shown rapid extractive power, but relevant compound degradation. On the contrary, cold infusion extracted higher level of healthy molecules with slow kinetic. The innovative method achieved in short time similar properties of cold infusion in terms of antioxidant power. As for bioactive compounds, such as gallic acid and epigallocatechin gallate, highest values, about double than in hot infusion, were recorded for green and black teas. This steeping method may represent an alternative approach for industrial beverage preparation.

Temperature and Time of Steeping Affect the Antioxidant Properties of White, Green, and Black Tea Infusions

“…According to Venditti and others (), the levels of total polyphenols of green tea were higher in hot water for the 7 min extract compared to the cold water 2 h extraction method. However, another study reported that the green tea health benefits in terms of antioxidant power maximized in cold water infusion with long steeping time (Lantano and others ). In this study, no significant difference in the levels of total polyphenols of white and green teas were identified under different extraction methods except for cold water for 5 min.…”

“…The content of total flavnoids in the different tea extracts were significantly dependent on time of extraction and varied from 731 to 2076 (Silver Needle), from 933 to 1538 (Shou Mei), from 1050 to 1497 (Chinese green tea), from 955 to 1435 (Japanese green tea), from 1004 to 1819 (BOH black tea), and from 1040 to 1931 (Lipton black tea) mg quercetin/g dried weight. It has been suggested that the antioxidant profile of the different type of teas is affected by their different methods of production (Vinson and Dabbagh ; Castiglioni and others ; Lantano and others ; Venditti and others ).…”

“…In a recent study conducted by Lantano and others (), the composition and antioxidant property of cold and hot infusion of green, black, and oolong teas for various durations were investigated, along with brief hot infusion followed by ice addition. Similar to our results for green tea, the higher values of bioactive compounds was reported in cold infusion compared to hot infusion.…”

An Update on the Health Benefits of Green Tea

“…In addition, where the leaves are grown (geographically) and the growing conditions affect catechin amounts [3,[9][10][11][12]. Polyphenols are quickly oxidized after harvesting due to the enzyme polyphenol oxidase.…”

Voltammetric determination of polyphenolic content as rosmarinic acid equivalent in tea samples using pencil graphite electrodes

“…Despite the fact that catechins represent the main polyphenols in these types of teas it is known that the tea leaves also contain phenolic acids which have an important contribution to the teas total antioxidant capacity (Dias et al 2014). The composition of white, green and black teas found all over the world depends on factors like cultivation region and harvesting time (Dias et al 2014;Lee et al 2014) whereas the composition and antioxidant activity of tea infusions are influenced by their preparation methodologies (Lantano et al 2015).…”