Lipolytic activity of viscera extract from three freshwater fish species in Phatthalung, Thailand: Comparative studies and potential use as dishwashing detergent additive

Abstract

Abstract Lipolytic activities of viscera extract from three freshwater fish species including hybrid catfish (Clarias macrocephalus × Clarias gariepinus), snakehead (Channa stiata) and Nile tilapia (Oreochromis niloticus) were studied. Optimal activity from all species was at pH 7.0–8.5 and 40–45 °C. Among all species tested, Nile tilapia showed the highest activity, followed by snakehead and hybrid catfish. The enzymes were stable to heat treatment up to 40 °C and over a pH range of 7.0–10.0 for 30 min. Lipases from the viscera of three fish species were enhanced in the presence of NaN3. However, the lipase activities from all species were inhibited by MgCl2, MnCl2, HgCl2, AlCl3, CuCl2, EDTA, EDAC, DEPC, PMSF, CTAB, sodium percarbonate and sodium polyacrylate. The Nile tilapia lipase was more stable against surfactants than both snakehead and hybrid catfish lipases. The effect of extractants on lipase recovery from Nile tilapia viscera was studied and its stability in the presence of different commercial dishwashing detergents was also investigated. Nile tilapia viscera powder isolation with 50 mM Tris-HCl, pH 7.0 containing 1.0 M NaCl and 0.2% (v/v) Brij 35 gave a higher lipase recovery than other extractants tested (p