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INFLUENCE OF DIET ON FISH QUALITY AND FATTY ACID PROFILE

By: Dr Mustapha ABA Aquaculture Researcher, Fish nutrition Morocco.

Nutrition is a critical factor in maintaining health, and the principle “Let food be your medicine and medicine be your food” was articulated by Hippocrates 2,500 years ago and this basis has been observed in several studies  in recent years. In the past, fish was consumed to survive, so quality was not a priority. Over the past decades, consumers have a major concern for the well-being and reduction of disease risks and for a better quality of life in relation to the quality of food, which has improved considerably.

Introduction

With a world population estimated at 9 billion people in 2050, it is necessary to seek alternatives and technologies to meet the growing demand for food.

Fish has been used as a food source by humans for millennia. Previously, we ate fish to survive, so quality was not a priority. In recent decades, consumer concerns about food quality have increased significantly, making them synonymous with well-being and reduced risk of disease, as well as vehicles for a better quality of life.

In this sense, the quality and excellence of fish as a food is undeniable, since it is a source of high biological value proteins and polyunsaturated fatty acids (PUFAs), which are known for their many benefits on human health.

Role of aquaculture in global food security

With overfishing for the main species and stabilized fish production, aquaculture was considered the most effective way to achieve the objectives of reducing the gap between supply and demand for fish on the world market. According to the FAO, the share of aquaculture activity in the development of world fish production has increased from 25.7% in 2000 to around 50% in 2018. With the stagnation of fisheries, the expansion of aquaculture activity has been for several countries a main driver of job creation, an essential alternative to ensure food security and a reliable solution for boosting international trade and economic and social development.

Over the last thirty years, the aquaculture sector has developed, diversified, intensified and made major technological advances, resulting in a significant increase in its contribution to aquatic food production. A large part of the world’s production is produced by small producers in developing countries, who require technical support and training in order to contribute more to food security, especially in African countries.

Influence of diet on the fatty acid composition of aquatic organisms

But one of the main challenges of aquaculture is to present the consumer with a final product that is similar in nutritional and sensory terms to fish caught in the wild. It is known that there are variations in nutrient composition and physico-chemical and sensory properties between “wild” and “farmed” fish in aquaculture, with diet being one of the main factors affecting these properties. That is, fish nutrition, in addition to directly influencing structural integrity, health, physiological functions, growth and water quality, also plays an important role in several fish quality parameters, such as colour, appearance, flavour, taste, texture, nutritional value.

Fish quality can be assessed using different parameters: yield (e. g. fillet), dripping loss, texture, colour, fat content, fatty acid (FA) composition, amino acid composition, mineral content, microbiological count, presence and quantity of contaminants, etc.

Recognized as a source of high quality protein, fish flesh has been the subject of numerous studies and research related to its composition in GA, which are directly associated with human health through its composition in GA protective effect, mainly against cardiovascular disease and rheumatism.

The composition of fish GA can be influenced by a number of factors, including temperature, salinity and diet. However, the main factor influencing the GA profile is diet, and several authors report that the GA composition of muscle tissue reflects the GA composition of the diet.

Freshwater and marine fish differ in terms of the composition of the GA. This is associated with several factors, including differences in the biochemistry of essential AG metabolism in marine and freshwater fish and the composition of food ingested in both habitats.

Therefore, the fortification of feed for aquatic organisms represents the possibility of grouping together in fish farming, through the production of high quality meat for human consumption, adapting to the evolution of fatty acids to meet market demand.

The quality of fish as a food is indisputable, since it is an important source of protein and fat. The recommendation for eating fish is at least twice a week. However, consumption is highly dependent on factors such as habit and economic aspects that involve fish consumption.

Fish is generally low in saturated fats, carbohydrates and cholesterol and provides not only high value proteins, but also a wide range of essential micronutrients, including various vitamins, minerals and polyunsaturated fatty acids from the Omega-3 series.

As mentioned above, the AG profile of fish can be influenced by a number of factors, including temperature, salinity and diet (lipid source). It is known that, among these factors, diet has a major influence on the composition of fish GA, reflecting in muscle tissue the GA profile present in the diet. As the essential GA is not synthesized again, the GA incorporated into the tissues represents their content in the food intake.

The use of oils in animal feed has increased in recent years, due to the many benefits that their inclusion can bring to both animal performance and human health. Among the most common sources of fat used in the formulation of animal feed for aquatic organisms are fish, soybean, corn, flax, canola and sunflower oils,

With the increase in the commercial value of fish oil, due to the increase in demand and the difficulty in obtaining fish oil. Research on quality products has been directed towards evaluating the use of sources of plant origin.

The dietary enrichment of fish flesh with omega-3 has been evaluated by several studies through the inclusion of increasing levels of fish oil as a substitute for sunflower or flax oil in the diet of Nile tilapia (Oreochromis niloticus). An increase was observed in the concentrations of α-linolenic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) AG in fillets as the concentrations increased from sunflower or flax oil to final phase fish oil in the diet.

Improving the nutritional quality of fish flesh, through the use of lipid sources in aquaculture feed, is possible, the producer’s objective is to improve the nutritional quality of fish, and to offer a rich product in AG n-3, to a growing consumer market in search of healthier foods.

About Dr Mustapha . A

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