Effectiveness of chitosan-tripolyphosphate nanoparticle dispersion in ice for fresh tilapia fish (Oreochromis niloticus) preservation

Tilapia (Oreochromis niloticus) is a major commodity in Indonesian freshwater fish market due to its convenience in cultivation. Regardless of its potential, the perishability of fresh tilapia limits the distribution. Common technique used by Indonesian fish market for fish preservation is cooling method using ice blocks packed with the fish in styrofoam boxes. However, this method is expensive because the ice should be replaced when it is melted. Combination between ice and appropriate preservative agent is a simple solution to reduce preservation cost. Chitosan, a natural polysaccharide which is obtained from deacetylation process of chitin from crustacean shell, can be used as natural preservative because its positive charges induce antibacterial activity. Chitosan is also non-toxic and biodegradable so that it is compatible with food products, including fish. Its antibacterial activity has been proven in other studies to be more effective in nanoparticle form. Nanoparticle of chitosan is synthesized by ionic gelation method using tripolyphosphate as crosslinker. This research evaluated the effectiveness of chitosan-tripolyphosphate nanoparticle dispersion in ice to be compared to plain ice in preserving fresh tilapia fish. The study was focused on finding the optimum nano-chitosan ice-fish ratios to reduce ice requirement in preventing the deterioration parameters of the fish. The extent of spoilage was represented by Total Plate Count (TPC), Total Volatile Base (TVB), and organoleptic assessment. The result highlighted the benefit of the dispersion of nano-chitosan in the ice blocks. With respect to fresh tilapia preservation, the dispersion of nano-chitosan in ice reduced the amount of ice up to 25% reduction of current practice using plain ice. With the optimum fish/ice ratio of 1:0.75, the nano-chitosan-dispersed ice could restrain the spoilage up to 24 hours without new addition of ice as long as the temperature has not reached the ambient temperature. This results were promising to reduce the risk of fish deterioration during distribution while also reducing the cooling cost and providing more space for fish in the storage by reducing the amount of ice to be packed in it.