Evaluation of a Freshness Sensor and its Application for Estimating the K Value of Fish Meat being put in Market

Abstract

It is reported that freshness of fish meat can be expressed by the K value according to the following calculation: K value (%)=(HxR+Hx)×100/(ATP+ADP+AMP+IMP+HxR+Hx). A freshness analyser, a kind of biosensor, was recently manufactured by the Oriental Electric Co., Niiza-shi. We examined the availability of this sensor and confirmed that the K value was obtained with a sufficient accuracy for practical application, within several minutes. Using this sensor, we determined the K values of fishes being put in the market. The samples used were horse mackerel (Trachurus japonicus), sardine (Sardinia melanosticta), saury pike (Cololabis saira) and pacific herring (Clupea pallasi) purchased from a departmentstore (A), supermarkets (B, C, D) and private retail stores (E, F). The K values of the samples increased up to 50% within several hours at 13-16°C and within 4 days at 3-5°C, respectively, but not at -20°C. The K values of the samples were diversed at every fish, every store, and every date of purchasing. It looks very hard to find the type of store where we can get the best goods. If the freshness of fishes were indicated by the K value labelled on package, it would be very convenient for the customers in choosing the fresh goods at store.