Abstract Omega-3 poly unsaturated fatty acids (PUFA) have numerous human health benefits. Fish oil has been known as a source of PUFA, but their addition to foods is limited by oxidative rancidity. Hence, fish oil has to be protected against oxidation preferably by microencapsulation. In the present study, an attempt was made to prepare fish oil encapsulates. Fish oil- milk based emulsion was prepared and encapsulated by spray drying using either fish gelatin or maltodextrin as wall materials. Fish oil and wall material was used at the ratio of 1:2. In order to study the effect of natural antioxidants on the fish oil encapsulates, ginger essential oil was added at 0.25% concentration. Morphological characterization of fish oil encapsulates by scanning electron microscopy (SEM) revealed spherical shape of particles without any cracks. Encapsulation efficiency was improved significantly (p<0.05) from 34.48-35.52% to 44.42- 49.34% by the addition of fish gelatin or maltodextrin as wall material. Fish oil encapsulates were packed in two different ways which include normal and vacuum packing and stored at room temperature (28–2C). Oxidative stability of the fish oil encapsulates showed better protective effect against oxidation (1.99 mg malonaldehyde kg -1 ) for fish oil encapsulates pre- pared with fish gelatin and ginger essential oil and packed in vacuum condition than the control (8.22 mg malonaldehyde kg -1 ). Results from the study indi- cated that fish gelatin was able to encapsulate fish oil and it was comparable with that of maltodextrin. Addition of essential oil as natural antioxidant im- proved the oxidative stability of fish oil encapsulates. Keywords: Microencapsulation, spray drying, fish oil, oxidative stability, essential oil Received 07 August 2013; Revised 17 November 2013; Accepted 19 November 2013 * E-mail: jeya131@gmail.com Microencapsulation of Fish Oil-milk Based Emulsion by Spray Drying: Impact on Oxidative Stability A. Jeyakumari 1 *, D. C. Kothari 2 and G. Venkateshwarlu 3 1 Central Institute of Fisheries Technology, P.O. Matsyapuri, Cochin -682 029, India 2 Department of Physics, University of Mumbai, M.G Road, Fort, Mumbai - 400 032, India 3 Central Institute of Fisheries Education, Versova, Mumbai - 400 061, India Fishery Technology 51 (2014) : 31 - 37 Introduction Fish oil represents a functional food ingredient, which contains important components for mainte- nance of good health and prevention of a range of human diseases via its beneficial effects on the heart, brain and nervous system (Wu et al., 2009). Autoxidation of polyunsaturated fatty acids (PUFA) in fish oil leads to the development of volatile secondary oxidation products and limit the shelf-life of the foods (Lee et al., 2006). Due to reasons like contribution of unsaturated lipids to health protec- tion and economics, many investigations have been undertaken with the aim to enhance the stability of lipids and lipids containing products. Application of antioxidants is one of the technically simplest ways of reducing fat oxidation (Karpinska et al., 2001). Emulsion systems are being utilised for delivery of lipophilic health active compounds, such as PUFA, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) where they provide convenient and practical means for delivering these nutrients in human diets (Augustin & Sanguansri, 2003). Generally, fish oil in its natural state has a taste and smell that makes it less attractive to consumers. Processing technology to mask the smell and taste in food systems is facing a great challenge. Interest in the encapsulation of long-chain polyun- saturated omega-3 oils is rapidly growing due to their beneficial health effect. Encapsulation is a rapidly expanding technology with a lot of potential in different areas including pharmaceutical and food industries. Among the different techniques available, spray drying is the most important technique for the encapsulation of bioactive food ingredients (Desai & Park, 2005). Spray drying is a well-known technology in the food industry and is the most commonly used microencapsulation tech- nique. It is also useful for the processing of heat- sensitive materials due to very short exposure time of product to heat. Before spray drying, the formed ' 2014 Society of Fisheries Technologists (India)