12th Pacific Science Inter-Congress, 8-12 July 2013

University of the South Pacific, Laucala Bay Campus, Suva, Fiji

SHELF-LIFE PREDICTION OF COLD-SMOKED TILAPIA

Janice Natasha1 , Jimaima Lako1, and Graham Robin South2

1University of the South Pacific, Laucala Campus, Fiji. E-mail Address:

1University of the South Pacific, Laucala Campus, Fiji. E-mail Address:

2University of the South Pacific, Alafua Campus, Samoa. E-mail Address:

Production of tilapia, Oreochromis niloticus, from the aquaculture sector in Fiji is on the rise, however commercialization is limited only to live fish. In view of this, cold-smoked tilapia products were developed to provide alternative taste and their shelf-life were predicted. Chemical, microbial and sensory evaluation were conducted on vacuum packed, cold-smoked tilapia to estimate shelf life that were stored for a 20-week trial period at 5°C (referigerated) and -18°C (frozen). Results revealed that psychrophilic total viable count of referigerated cold-smoked tilapia reached its maximum level of 6 log cfu/g after 3 weeks, however, the shelf-life of the product was estimated to be 6 weeks by the sensory panelists. Frozen cold-smoked tilapia remained within the acceptable limit throughout the 20-week storage period. Rancidity level remained very low throughout the storage period due to inhibition of lipid oxidation by the total phenols in the product. The threshold level of 25mg N/100g of Total Volatile Base – Nitrogen (TVB-N) was reached at sensory rejection. Trimethylamine (TMA) did not play a significant role in spoilage as only small amounts were produced. Enterobactericea predominated the spoilage flora. Other spoilage microorganisms found at sensory rejection included Lactic-acid producing bacteria (LAB), psychrophilic Clostridia spp. and yeasts and mould. High counts of Enterobacteriacea at rejection time may be attributed to pond water quality in which tilapia were reared. Shelf-life can be maximised through purging of live tilapia before slaughter and through hygenic handling of fish during processing.

Key Words: Cold-smoked tilapia, shelf-life, spoilage organism, Enterobactericea.