M. HABARA (1), H. Ikezaki (1); (1) Intelligent Sensor Technology, Inc., Atsugi, Kanagawa, Japan

Sensory I
Wednesday, June 4 - 10:00 a.m.-11:45 a.m.
Level 4, Red Lacquer Ballroom

An accelerated test at 25, 36, and 45°C (77, 96.8, and 113°F) for 30 days was investigated for taste quality assessments using an e-tongue system. Major bottled draft beers, with the same date of packing, were used as samples and stored in three different constant temperature reservoirs at each temperature. Sample preparation was as follows. 1) Take one quarter of the bottled beers as a control and then keep them in a refrigerator at 8°C (46.4°F) to prevent further degradation. Meanwhile, allow the remaining three-quarters of the samples to degrade with time. 2) At day 10 and 20, take each one-third of the remaining bottles that have degraded, and keep them in the refrigerator. Meanwhile, continuously allow the other samples to degrade with time. 3) At day 30, prepare the final sample, and measure these four samples at one time by using the e-tongue system TS-5000Z (Intelligent Sensor Technology, Inc., Japan). These instruments have been widely used in the Japanese food, beverage, and pharmaceutical industries since 1993. The taste sensor applies potentiometric measurement with originally designed taste receptor membranes by mimicking human gustatory sensation. The instrument provides not only information on taste quality but also time-dependent taste change such as initial taste and its aftertaste. The assessment was conducted with five taste sensors indicated as bitterness, sourness, saltiness, umami (savory), and astringency. Each sensor was designed to selectively respond to a single basic taste and to correlate its sensitivity with the human gustatory sensation. The bitterness sensor used in this experiment was designed to highly correlate with bitterness units in order to evaluate beer bitterness as reported at the ASBC Annual Meeting in 1999. All sensor outputs are converted into a “taste scale” that is based on a concept of the Weber-Fechner law of human perception so that taste intensity should be easily recognizable for users. The results revealed that as temperature and time increased, perceptible change, both in the initial taste and aftertaste of bitterness, were mainly observed in the direction of less intensity. At 25°C, no significant change was obtained, but at 36°C, initial taste of bitterness exceeded the perceptible limit after 20 days. At 45°C, after 10 days the initial taste of bitterness exceeded the limit, and after 20 days, the aftertaste exhibited perceptible deterioration. Though detailed consideration of the results is in progress, the change in taste quality has the possibility of correlating with a formulation derived from the Arrhenius equation. Our results also showed that draft beers produced by different manufacturing processes exhibited slightly different deterioration speeds, suggesting that the brewing process also effects shelf life. This assessment method has a broad utility for quality assessment based on the three primal factors of deterioration. Not only is there a temperature acceleration but also for light and oxidation effects on taste quality.

Masaaki Habara received his B.E. and M.E. degrees, both in electrical engineering, from Kanazawa Institute of Technology in 1995 and 1998, respectively, and his Dr.Eng. degree from Kyushu University in 2002. He worked as a visiting associate professor in the Graduate School of Information Science and Electrical Engineering of Kyushu University until 2011, when he joined Intelligent Sensor Technology, Inc. as a research and development engineer.