Utilisation of gelatine from NZ hoki (Macruronus novaezelandiae) fish skins

Response Surface Methodology (RSM) was adopted to optimize the extraction conditions of hoki (Macruronus novaezelandiae) gelatine and some of the physico-chemical properties were characterised. The optimum conditions obtained for fish gelatine extraction were 0.75 M concentration of NaCl for 9 min of pretreatment time and hot water extraction at 49.3°C for 60 min. The predicted yield achieved by RSM (17.4%) intently matched the experimental yield of 17.6%. Even though gel strength of hoki gelatine was significantly higher than those from other cold water fish species as reported in previous studies, it was lower (197 ± 5 g) than those from porcine (307 ± 8.4 g) or bovine (273 ± 16.1 g) gelatine. Therefore, enzymatic modification was applied to improve the properties (especially gel strength) of hoki gelatine, thereby enhance their effective use as foods and food ingredients. The addition of transglutaminase (TGase) enzyme at the concentration of 3.0 mg/g in gelatine increased the gel strength from 197 g to 279 g, which could therefore lead to the formation of products with enhanced rheological as well as sensory properties.