Impact of initial handling on quality and shelf life of penaeid shrimps by artisanal fishermen in Kurawa North Coast, Kenya

Abstract

The present study was conducted to determine the effect of initial handling of shrimps after they were caught by the small scale fisheries of Kurawa North coast Kenya. Further, the study was aimed at assessing the effect of the initial handling on shelf life during storage under different packaging conditions. The study site was situated at Kurawa landing site North coast Kenya along Malindi-Ungwana Bay which extends from Malindi in the south to Ras-Shaka in the north. Shrimps were subjected to immediate icing after catch while others were iced immediately they were landed at the landing site. The subsequent sub-sampling of the samples for icing was done every 2 hours to a maximum of 6 hours. Samples were stored in ice for a period of 12 days under ambient (atmosphere) air and vacuum packaging conditions. Biochemical quality parameters, specifically Total Volatile Bases-Nitrogen (TVB-N), Trimethylamine-Nitrogen (TMA-N), Peroxide Value (PV), p-Anisidine Value (p-AV) and proximate composition (dry matter, crude protein, crude fat and ash) were used to monitor quality changes during initial handling (preliminary treatment before icing) and storage. Control (samples iced immediately after catch) samples had good biochemical and proximate quality attributes than those that underwent delayed icing. Mean TVB-N values for the control, 0, 2, 4, and 6 hour delayed icing samples were 1.84 ± 0.30 mg N/100 g, 5.34 ± 0.55 mg Nil 00 g, 8.60 ± 0.43 mgN/I00 g, 13.l6± 0.83 mgN/100 g and 16.04± 0.78 mgN/100 g, respectively. During initial handling, TVB-N, TMA-N, PV and p-AV increased significantly (p < 0.05) throughout the delayed icing period with 6hours delayed icing giving values of 16.04 ± 0.78 mg Nil00 g for TVB-N, 4.38 ± 0.25 mg Nil 00 g for TMA-N, 16.25 ± 0.90 meq O2lkg for PV and 50.85 ± 0.85 meq 02/kg. Biochemical quality parameters for both samples stored under ambient air and vacuum packaging conditions increased significantly (p < 0.05) throughout the storage period. Control samples exhibited better shelf life than O-hour samples, followed by 2, 4 and 6-hour samples. Lower values of TVB-N, TMA-N, PV and p-AV were observed with the vacuum packaging samples compared to ambient (atmosphere) air packaged ones. Proximate composition did not change significantly except for control samples. A comparison of the effect of vacuum vs. ambient air packaging on the shelf life of shrimps indicated better performance with vacuum packaging compared to ambient air packaging. In general, samples iced immediately after catch (control), followed by 0 and 2 hours had better shelf life than those iced at 4 and 6 hour after catch. Therefore the study concluded that delay in icing of shrimp during the initial handling affects significantly the quality and shelf life of shrimps during storage.