Electronic nose evaluation of volatile emission of Chinese teas: from leaves to infusions

An electronic nose can be used to discriminate tea leaf quality, but to the best of the author's knowledge, studies that address the changes in electronic sensor signals between tea leaves and infusions are not available. In this framework, this preliminary work compared the volatile emissions of leaf samples belonging to the basic Chinese teas (white, yellow, green, oolong, black and pu erh) with those of their respective infusions using an electronic nose. Different signal responses were qualitatively and quantitatively obtained from the sensors both for the tea leaves and their respective infusions, showing that the leaf aroma is not transferred as it is into the beverage. The teas were grouped according to the different fermentation techniques based on the percentage variations in the sensor contributions to the complete description of the volatile profiles. The results indicated that the electronic nose is a suitable tool to monitor the volatile emission differences that occur between leaves and infusions in different tea types.