Combination of chitosan coating and clove essential oil reduces lipid oxidation and microbial growth in frozen stored tambaqui (Colossoma macropomum) fillets

This study evaluated the synergistic effect of chitosan coating and clove essential oil (CEO, Syzygium arornaticum) on the preservation of frozen tambaqui (Colossoma macropomum) fillets. Fillets were divided into five groups and subjected to the following treatments by immersion: chitosan, chitosan + CEO (at two different concentrations), and controls, butylated hydroxytoluene (BHT; a commercial antioxidant) and water. Following treatments, fillets were individually packaged using polyethylene plastic film and were stored at -18 degrees C. Physico-chemical (pH, moisture, and lipid oxidation), microbiological (cultivable psychrotrophic bacteria), and sensory analyses were performed for 120 days. Treatments with chitosan 2% and chitosan + CEO (0.16% and 0.08%, respectively) effectively delayed lipid oxidation ( < 0.83 mg eq. kg MDA(-1)), inhibited the growth of culturable psychrotrophic bacteria, and reduced pH and moisture at 120 days (p < 0.05). Sensory analysis revealed that tasters preferred the chitosan-treated and control fillets (p = 0.1661) to the chitosan + CEO-treated fillets (p = 0.05192), as all gave these fillets scores > 5 (i.e. liked the fillet). Based on these results, the combination of chitosan and CEO shows promise as a natural preservative as it can inhibit the chemical and microbial deterioration of frozen tambaqui fillets, and could potentially be used to preserve the fillets of other fish.