2.2. E-tongue based evaluation of taste

Taste was evaluated with the potentiometry based α-Astree Electronic tongue (Alpha MOS, France) using Sensor Array # 5 and a reference electrode. The array had seven sensors with three of them tuned each to sour (S1), salty (S3) and umami (S4) tastes. The other four sensors gave an integrated response. The electrochemical signals from the sensors were stored as data matrix and used for multivariate analysis. The response of each sensor was assessed on a relative intensity scale of 1–10, from the least to the most intense taste perception. All samples except E. officinalis were dry and powdered. 50 ml of distilled water was added to 5 gm of each sample, placed in a 40 °C water bath for 1 h, gently stirred every 10 min and then macerated. E. officinalis was chopped to small pieces and blended with water for 1 min. All the prepared solutions were filtered to remove any suspended particles, left at room temperature for 1 h and used for analysis. The following were the experimental conditions: sample volume – 20 ml; acquisition time – 120 s; time per analysis – 180 s; four replicates per sample.