Kenyan fish guts can be turned into valuable fish oil

In developing countries, fish organs are usually thrown away as waste, but scientists say there is a simple way to turn fish guts into a valuable fish oil product. They describe a simple process to extract oil from the internal, or visceral, organs of Nile perch fish sourced from a Kenyan market.

Japan, the USA, Chile and Peru produce most of the world’s fish oil, but developing countries like Kenya turn masses of its fish biowaste (biological fish material left over after the flesh is removed, such as the organs) into this valuable product for the global market.

In this study, researchers wanted to find a method to extract fish oil from fish biowaste. They wanted to adapt an existing “wet processing extraction” technique that involves heating it to release the oil from the tissues, and then washing the oil to remove other impurities. 

The researchers collected Nile perch visceral organs (the chest, heart and other internal organs) from fish filleting factories in Kenya. 

They extracted the oil from fish guts at high temperatures - they used 80, 90, 95 or 97 degrees celsius. 

Next they separated the oil from the biowaste using a sieve, and washed the oil using a mixture of warm water and pineapple juice. They also tested different temperatures for the warm water. This sieving and washing process was repeated several times for a clean, pure oil product.

They measured the amount of fish oil they were able to extract at the various temperatures, as well as the levels of Omega-3 fatty acids and vitamins, which indicate the quality.

They were able to extract the most fish oil by heating the fish biowaste to 80 degrees celsius for 30 minutes. The best quality oil was achieved when they washed with water warmed to 95 degrees celsius. 

Given that developing countries like Kenya do not produce much of their own fish oils, the process described here could help boost the industry. The Kenyan researchers hope their method will ultimately help to create jobs, local fish oil products, and less fish biowaste. 

Abstract

Global fish oil production is between 1 to 1.25 million tonnes and primarily exploiting fatty fish such as menhaden, herring, pilchards, anchovy, and sardine among others. The main producing countries include Japan, USA, Chile and Peru. Yet, fish oil from developing countries end up as bio waste since only the flesh is utilized. This paper discusses a simple approach for utilizing the fish bio waste to produce oil and how the oil quality and quantityis impacted by the extraction process. The visceral organs were collected from fish filleting factory and markets in Kisumu town and oil extracted by modified wet pressing method adopted from Blight and Dyer (1959). The effect of temperature and serial washing on the oil quality and quantity was assessed from extraction temperatures at 800C, 900C, 950C and 970C, while employing three serial washing using distilled water and pineapple juice. The quality of the oil produced was then determined based on the proportion ofomega -3, vitamin A and E, peroxide value, iodine value and free fatty acids. Results indicate that maximum extraction efficiency was achieved at 800C for 30 minutes where 156.05g of oil was extracted, when compared to 155.32g at 90ºC,155.24g at 95ºC,155.23g at 97ºC from a tissues of 171.25gin each case. The data was then analyzed using ANOVA at P<0.05 and post hock to determine significance. It was concluded that the temperature manipulation procedures as per this study was reliable to produce maximum yield and can be adopted by oil producing plants.

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