"The main problem is that fish production is stigmatized. People often say that they do not like freshwater fish because of the taste of clay, which they mistakenly consider to be an intrinsic characteristic of fish from rivers and lakes"

 Freshwater fish is still little consumed in the country and one of the reasons is the identification of consumers by the "taste of clay" in fish meat. The São Paulo Agribusiness Technology Agency (APTA), of the São Paulo State Department of Agriculture and Supply, develops research to guide aquaculturists to manage production correctly and avoid losses with the so-called off-flavor, which may make it impossible to selling the fish to large slaughterhouses or halving the value for sale in smaller processing units.

According to the APTA researcher, Gianmarco Silva David, the cause of unpleasant taste comes from substances called geosmina and methyl isoborneol (MIB) associated with the aroma of clay and mold produced mainly by cyanobacteria and eventually streptomycetes, organisms that live in the same environment of fish culture.

The APTA researcher says that the more water gets dirty, the more likely there will be problems with off-flavor. "Contrary to many people's beliefs, the fish farmer does not grow fish, but rather clean water. Only with clean water is it possible to produce healthy and quality aquatic organisms, and therefore the importance of environmental preservation," he says.

In order not to soil the water, it is necessary to dimension the capacity of the environment to support the fish production. Efficiency is another factor pointed out by Gianmarco. According to the researcher, it is necessary to evaluate the quantity of ration adequate for the production, to work with high quality ration and to avoid that the animals become stressed, impairing the good feed conversion. In addition, it is important to dispose of waste correctly.

"We have developed, for example, a work in Ilha Solteira, the main fish producing region of the State, identifying situations that can lead to loss of water quality and support producers to improve quality and value production, "he explains.

APTA, in partnership with the Paulista State University (Unesp) and the Danish universities University of Copenhagen and Aalborg University, has developed a thematic research project funded by the Foundation through the Regional Pole of Bauru and the Institute of Fisheries (IP-APTA) (FAPESP) to study the off-flavor. The project was finalized in 2018 and has already originated several publications of articles in international scientific journals like Aquaculture Environment Interactions and International Journal of Fisheries and Aquatic Studies.

 

Estimated losses

The 2019 Peixe BR Yearbook shows that the Brazilian production of fish was 722 thousand tons in 2018 and the São Paulo company 73 thousand tons. According to Gianmarco, estimates indicate that in about 10% of production there are problems related to off-flavor, which would generate a loss of approximately R $ 13 million in the State of São Paulo.

This loss, however, is much higher, according to the researcher. "The main problem is that fish production is stigmatized. People often say that they do not like freshwater fish because of the taste of mud, which they mistakenly consider to be an intrinsic feature of river fish and lakes. of fish, which has worked to mitigate the problem, avoiding the processing and sale of fish with problems of off-flavor. This is a barrier to the growth of the national market, "he explains.

 

Water Quality Laboratory

The Fisheries Institute maintains in São Paulo one of the only laboratories in Brazil to concentrate physical, chemical and biological analyzes of water to support the environmental sustainability of activities related to the aquatic environment. The Water Quality Laboratory of IP is qualified to serve different sectors of agribusiness, in particular activities focused on fishing and aquaculture, depending on the quality of water resources. "This laboratory is very important for our off-flavor research, with great synergy with the APTA teams that work in the interior of the State, meeting the regional demands of aquaculture. Clean water is the main issue for the producer to avoid the problem and make available to the industry and consumer products of high quality, "says Gianmarco.

 

By Fernanda Domiciano

Press Office - APTA

19 2137-8933

 

Source and image: Fisheries Institute