Abstract
The rapid and objective judgements of the freshness of raw oysters in Hiroshima district were carrid out using fuzzy reasoning based on the three kinds of biochemical indicator such as respiration activity of oyster gills (succinate dehydrogenase, SDH), pH and anmonia concentration of the body fluid. During the storage of oyster, SDH and pH were smoothly decreased with time elapsing, on the contraly, anmonia concentration was increased. It would suggest that these indicators were closely related to the freshness of oyster. By fuzzy reasoning based on these three indicators, a new system to estimate the freshness with the score of 0-100 point was developed. Estimated freshness points were in good agreement with the sensory judgements by seversl professionals of oyster farms. Moreover, the estimations of freshness by fuzzy reasoning indicated superior judgement compared to those by the conventional judgement using multiplicative average method which was developed previously.
