Changes in total volatile base nitrogen (TVB-N)
TVB-N concentration of Indian mackerel upon freezing and
frozen storage is given in Figure 6. The initial TVB-N content of
mackerel used in the study was 9.27 mg 100/g flesh. Upon freezing,
it increased slightly to 10.6 and 12.5 mgN2100/g in air blast and
plate freezer, respectively.During the storage period of 3mo, TVB-N
was increased in air blast frozen samples compared to plate frozen
samples (20.39 and 18.64 mg N2100/g, respectively). The level of
TVB-N in freshly caught fish is generally between 5 and 20 mg N2
per 100 g muscle. However, the levels of 30 to 35 mg N2 per 100 g
muscle are considered the limit of acceptability (Huss 1988; Connel
1995). In the present study, the TVB-N content was well within the
limit of acceptability. This could be attributed to the freezing effect,
as it inhibits the bacterial activity