The effect of slaughtered and primary processing methods on Rigor mortis, quality parameters, bacterial and shelf-life on Caspian kutum (Rutilus kutum) during stored in ice

Abstract

Introduction: The Caspian kutum is an economic precious species in Caspian Sea. It is very
important to maintain the nutrition value with increasing of shelf-life until marketing.
Determining the best method of slaughtered in this species and proper marketing of fish with
acceptable freshness in the consumer market are the main aims of this study.
Materials & Methods: 4 treatments including fish with rapid death (due to branch cut) with
visceral emptying (treatment 1), rapid death without visceral emptying (treatment 2), common
death with visceral emptying (treatment 3) and common death without visceral emptying
(Control treatment, 4) all stored in ice. and from phase 0 to 16 days were evaluated for freshness
by performing qualitative tests.
Results: The results showed that the fish entered the rigor mortis stage at a later time in
emptying the visceral and rapid death method and left later than other treatments. Also, the
amount of TVN-N in this treatment reached an acceptable level of 19.26 mg/100 g by day 8
and the amount of TBArs reached 1.5 mEq of malon dialdehyde/1000 g, the pH of the
treatments from 5.75 to 5/76 were variable. The most total bacterial count was observed in
control treatment (6.6 log cfu/g).
Conclusion: Pprimary processing in post-harvest is effective on quality parameters. In terms
of freshness evaluation in the (treatment 1) until the 8th day was acceptable in all quality
indicators, but other treatments before that were spoiling and exceeded the acceptable level.