Preservative effect of NaCl in salted and dried fish products was studied. Salted and dried sardine Sardinops melanosticrus meat with NaCl added at various concentrations was stored at 25°C for 8-11 days under atmospheres which were controlled at aw 0.95 and 0.93. During storage, volatile basic nitrogen (VB-N) of the samples were determined as a spoilage indicator. The sample was judged to be stale, when its VB-N increased above 100 mg/100 g on dry basis which is equivalent to 30 mg/100 g on wet basis in the case of fresh fish meat with moisture content of 70%.
As a result, a high correlation was found between the aw and the shelf life of sample; the lower the aw the longer the shelf life. The aw of the sample was also highly correlative to NaCl contention (NaCI content×100/moisture content + NaCI content); the higher the NaCl concentration the lower the aw. From these results, it was suggested that the preservative effect of NaCl in salted and dried fish products was caused by the action of lowering aw, and not by the bacteriostatic action on growth of putrefying bacteria.