Freezing has a drastic effect on the cellular constituents of muscle. It is not possible to determine the original freshness of thawed fish since meter readings are invariably in the range of 0-3, whatever the quality before freezing. In fact, this property can be used in many cases to determine whether fish has been frozen at some time in its history. If the sample, judging by odour, appearance and flavour appears to be fresh i.e. should have a high meter score, but in fact gives a low reading then there are grounds for suspecting it has been frozen at some time. Once again judgment should not be based on one fish only; several fish should be examined.
Brining also lowers the reading though not quite as much as freezing. It is therefore not possible to check the freshness of brined fish.