Effect of Repeated Ingestion on Temporal Perception of Bitterness in Beer

The effect of repeated beer ingestion on perception of bitterness was investigated via a computerized time-intensity method. In a first experiment, five successive time-intensity measurements of bitterness of 0, 15, or 30 mg/ L of iso-α-acids added to beer were performed at 5- or 30-sec intervals by 12 judges. Duration of bitterness increased significantly (P <0.001)upon repeated ingestion, whereas maximum intensity of bitterness remained unchanged. Time to reach maximum intensity increased significantly (P <0.01) between the first and subsequent ingestions. Duration, maximum intensity, and time to maximum intensity increased significantly with concentration of iso-α-acids but were not affected by the time between measurements. In a second experiment, the effect of five successive ingestions at 20- or 40-sec intervals on temporal bitterness of 0 and 20 mg/L of iso-α-acids added to beer, served as 10 or 20 ml samples, was measured by 10 judges. Maximum intensity of bitterness and intensity of bitterness at ingestion increased significantly (P <0.001) upon repeated ingestion and with concentration of iso-α-acids. Only maximum intensity of bitterness increased significantly (P <0.01) with sample size. Intensity at ingestion was significantly higher (P <0.001) with 40 than with 20 sec between ingestions.