Nano-chitosan Utilization for Fresh Yellowfin Tuna Preservation

Chitosan utilization as a preservative agent for freshly caught fish has been studied intensively during the last ten years in Indonesia, but the effort was concentrated more on ponds-raised fresh water fish. In this paper we report our preliminary results of a study on using chitosan in the form of nanoparticle (nano-chitosan) to improve the shelf life of freshly caught wild young yellowfin tuna (YFT- Thunnus albacares, Bonnaterre 1788). Pharmaceutical grade chitosan was dissolved in 0.2 mM aqueous acetic acid and aqueous ammonium hydroxide was added to reach a certain value of pH at which 1% concentration of nano-chitosan particles was obtained. The YFT samples were immersed for 30 min in aqueous dispersion of nano-chitosan, and incubated afterwards at two different temperature settings (4 °C and 28 °C). The fish deterioration was measured in terms of Total Volatile Base (TVB) and bacterial Total Plate Count (TPC), with supporting data taken including organoleptic assessment, pH and water content. The nano-chitosan did not seem to decrease the number of bacteria. However, the TVB data indicated that nano-chitosan treatment significantly suppressed the bacteria activity and the effect was more pronounced at 28 °C.