Journal of the Science of Food and Agriculture J Sci Food Agric 83:1139–1142 (online: 2003) DOI: 10.1002/jsfa.1515 Lipase activity in different tissues of four species of fish: rohu (Labeo rohita Hamilton), oil sardine (Sardinella longiceps Linnaeus), mullet (Liza subviridis Valenciennes) and Indian mackerel (Rastrelliger kanagurta Cuvier) Jyotiranjan Nayak, PG Viswanathan Nair, ∗ K Ammu and Suseela Mathew Department of Biochemistry and Nutrition, Central Institute of Fisheries Technology, Matsyapuri, Cochin, Kerala, India Abstract: Lipase activity in stomach and pyloric caeca, liver, intestine and red muscle of rohu (Labeo rohita Hamilton), oil sardine (Sardinella longiceps Linnaeus), mullet (Liza subviridis Valenciennes) and Indian mackerel (Rastrelliger kanagurta Cuvier) was studied. Distinct differences in lipolytic activity in different tissues of these fish were observed. Rohu showed the highest activity in all tissues in comparison with the other three species of fish. Among the three size groups of mullet, medium-sized mullet showed higher activity than the other two groups in all tissues except intestine. Rohu hepatopancreatic lipase exhibited more hydrolytic activity on fish oil than rohu intestinal lipase.  2003 Society of Chemical Industry Keywords: crude enzyme; lipase activity; fish oil; intestinal lipase; mullet; fish species INTRODUCTION The widespread use of enzymes in industrial pro- cesses has necessitated the identification of cost- effective and easily available sources of these enzymes. Lipases (triacylglycerol acylhydrolase; EC 3.1.1.3), which catalyse the hydrolysis of fatty acid ester bonds in triacylglycerols and related com- ponents, are widely used in the dairy industry, 1 detergents, 2 the oleochemical industry, 3 the food industry 4 and the production of biofuels. 5 At present the main source of these enzymes is micro- organisms. Taking into account the growing demand, it is essential that alternative sources are identi- fied. Lipolytic activity has been detected in plants, higher vertebrates and micro-organisms, and lipases have been isolated and purified from various sources such as porcine pancreas, 6 rat pancreas 7 and micro- organisms. 8,9 The potential of fish and other marine organisms as a source of lipase is an area meriting detailed investigation. Studies on lipolytic activity in tissues of various fish are available. 10 – 13 The objective of the present work was to compare digestive and muscle lipase activity in marine, brackish and freshwater fish and to determine whether they can be a possible source of lipase for industrial application. MATERIALS AND METHODS Materials Fish employed in the experiments were Labeo rohita Hamilton (rohu), Sardinella longiceps Linnaeus (oil sardine), Liza subviridis Valenciennes (mullet) and Rastrelliger kanagurta Cuvier (Indian mackerel). They were collected from markets and farms in and around Cochin, India. Each time about 2–3 kg of fish were obtained fresh, transported to the laboratory in ice and analysed within 6–8 h of collection. Lipase activity in stomach and pyloric caeca, intestine, red muscle and liver/hepatopancreas of these fish was studied. In the case of mullet, three different size groups (see Table 2) were examined to evaluate any differences in enzyme activity associated with fish size. The chemicals polyvinyl alcohol (PVA), bovine serum albumin (BSA), tributyrin and sodium taurocholate were purchased from Sigma Chemical Company (St Louis, MO, USA). Fish oil from oil sardine (S longiceps) used in the experiment was obtained from a commercial source. The fatty acid composition of the oil is shown in Table 1. All other chemicals used were of analytical grade. Methods Preparation of crude enzyme extract All procedures in the preparation of the crude enzyme extracts were carried out at 0–4 ◦ C. Fish ∗ Correspondence to: PG Viswanathan Nair, Department of Biochemistry and Nutrition, CIFT, Willingdon Island, Matsyapuri-PO, Cochin 682 029, Kerala, India E-mail: pgvn@cift.ker.nic.in (Received 14 May 2002; revised version received 12 March 2003; accepted 14 May 2003)  2003 Society of Chemical Industry. J Sci Food Agric 0022–5142/2003/$30.00 1139