Characteristics of gelatin from lizardfish (Saurida micropectoralis) and threadfin bream (Nemipterus hexodon) skins as influenced by extraction conditions

Gelatins from lizardfish and threadfin bream skins were extracted using distilled water at 45 and 60 °C and 4, 8 and 12 h. Gelatin recovered from both lizardfish and threadfin bream skins was in the range of 63.96–91.46%. As extraction temperature and duration increased, the turbidity of gelatin solution from both species increased. Gelatins isolated from either lizardfish or threadfin bream skins at 45 °C for 4 and 8 h showed the maximum bloom strength (245.03–320.85 g), which were also greater than commercial gelatin from bovine (208.55 g) (P < 0.05). The gelatin gels (6.67%, w/v) could set at 4 °C within 3 min and were able to set at room temperatures within 51.83 min. Gelatins extracted from both fish skins contained α₁-, β- and γ-chains as predominant protein components. The lightness of all gelatin gels faintly declined with an increase in extraction temperature and time. Among the various production conditions explored, lizardfish/threadfin bream skin gelatin developed at 45 °C and 8 h was found to be highly comparable to commercial bovine gelatin. Based on the results obtained, gelatin from both fish species could be used as a replacement for land animal counterparts and can be used in many different food and pharmaceutical products. Graphical abstract: [Figure not available: see fulltext.].