Abstract:

In this study, the optimized extraction conditions of three factors, including tea sample dosage, equilibrium temperature and equilibrium time were determined using the L₉(3 ⁴) orthogonal test combined with single factor tests and taking the eigenvalue of 10 sensors as the indexes. The results showed that the influence degree of different extraction conditions on different sensors was different. The equilibrium temperature had the greatest influence on the response value of the eigenvalue of most sensors, while the equilibrium time had the smallest effect. The optimal conditions for the detection of volatiles in Oolong tea by the electronic nose were as follows: the equilibrium temperature was 100 ℃, the equilibrium time was 45 min, and the tea sample dosage was 3 g. Under the extraction condition, the RSD was smaller, the response curve of the sensor was denser and stabler than that of other extraction conditions, and the response value was the highest. Thirteen different varieties of Oolong tea could be clearly distinguished by the optimal conditions of electronic nose sensors. It would provide a fast and objective method for aroma-discriminating of Oolong tea and is an effective method of electronic nose detection.

Key words: oolong tea, electronic nose sensors, orthogonal test, optimum extraction conditions, volatile components