Combined Effect of Icing Medium and Red Alga Gracilaria verrucosa on Shelf Life Extension of Indian Mackerel (Rastrelliger kanagurta)

Flake ice refrigeration is a conventional but commonly employed technique to slow down fish spoilage and deterioration of nutritional values and sensory properties during chilled storage. In the present study, a methanolic extract of red alga Gracilaria verrucosa was characterised, and functional groups, such as alkenes, aldehydes, nitriles, galactans and galactose-4-sulphate were found. Subsequent identification of active compounds revealed the presence of potent preservative agents, such as butylated hydroxytoluene, sulfurous acid, 1,2-propanediol, benzeneacetic acid, cyclononasiloxane and tetracosamethyl-cyclododecasiloxane. The effect of incorporating G. verrucosa at two different concentrations (0.67 and 2.5 g lyophilised alga/L aqueous solution) in the icing medium was tested for the preservation of Indian mackerel (Rastrelliger kanagurta), compared to preservation in traditional ice prepared only from water. Microbial, chemical and sensory qualities were monitored in Indian mackerel chilled in ice with and without G. verrucosa during 15 days storage period. Inhibitory effects (p?G. verrucosa, respectively, relative to the control medium. The sensory score acceptability limit reached 11 days for Indian mackerel stored in traditional ice and 15 days for Indian mackerel stored in ice with G. verrucosa extract. Thus, the icing medium containing G. verrucosa extract improves the quality and safety of Indian mackerel during storage and can be explored by the seafood industry as a biopreservative.