A promising insight into the inhibition of lipid oxidation, protein degradation and biogenic amine accumulation in postmortem fish: Functional glazing layers of modified bio-polymer

This study focused on a glazing layer made by modified bio-polymer to inhibit chemical variations in super-chilled postmortem fish. Essential oils were extracted from tangerine peel and their major antioxidant and antimicrobial components were identified. The essential oils were introduced into chitosan material as functional agents to improve the performance as freshness-keeping glazing layers for super-chilled tilapia. During the storage, antimicrobial effects of glazing significantly decreased the bacterial growth, as the growth of total bacterial count (TBC) decreased from ∼12.8 log CFU/g to ∼ 3.5 log CFU/g and that of total aerobic count (TAC) decreased from ∼11.1 log CFU/g to ∼ 3.3 log CFU/g. Antioxidant effects of glazing led to decreases of peroxide value (PV) from 6.41 meq/kg to ∼2.5 meq/kg and thiobarbituric acid reactive substances (TBARS) content from 1.09 mg MDA/kg to ∼ 0.5 mg MDA/kg at the end of the storage. Glazing inhibited the change of corruption degree reflected by K-value and protein decomposition reflected by the contents of trichloroacetic acid (TCA) soluble peptides and total volatile basic nitrogen (TVB-N). Glazing also limited the contents of main biogenic amines (histamine, putrescine, cadaverine, spermine, spermidine, tyramine, tryptamine) within relatively low levels.