By 2030, aquaculture is expected to be the main source of fishery products in the world. This positive fact clashes with the fact that aquaculture relies heavily on fishmeal and fishmeal, soybeans and krill oil as essential ingredients for feed manufacturing, which puts significant pressure on marine and terrestrial ecosystems. In this work, sustainable alternatives to the use of traditional ingredients in the manufacture of fish feed will be assessed by evaluating the combination of three ingredients: (1) insect meal as a quality protein source, (2) microalgae biomass as a source of lipids rich in omega-3 polyunsaturated fatty acids and (3) protein and lipid fraction recovered from cooking water for tuna canning processes as new alternative.
In its first phase we focused on the optimization and production of alternative ingredients, 5 species of microalgae: Nannochloropsis gaditana, Tisochrysis lutea (CCAP 927/14), Rhodomonas lens (ECC030), Isochrysis galbana (CCAP927 / 1) and Phaeodactylum tricornutum Bohlin (CCAP 1055/1) and the pilot culture conditions were adjusted to get the highest quality lipid content. Lipid accumulation was higher in the stationary phase in the case of N. gaditana, I. galbana and T. lutea. R. lens and P. tricornutum accumulated more lipids in the exponential phase of growth. the fatty acid profile, showed that microalgae strain accumulate more PUFAs in the stationary phase except P. tricornutum , generally coinciding with the maximum accumulation of total lipids. N. gaditana accumulated mainly EPA; I. galbana stands out for its DHA content and R. lens and T. lutea accumulated mainly n-6 fatty acids.
Respect to tuna cooking water, the centrifugation, filtration and drying processes were optimized for the separation and concentration of the protein and lipid phases. Through the use of nanofiltration membranes, the protein was concentrated from the initial 1.5%, to 5.5%, recovering almost 80% of the protein. This concentrate was dried in a spry dryer to obtain a dry powder product with a protein content of 70-75%. Oil separated from the cooking water by centrifugation, showed similar fatty acid profile observed in a commercial fish oil.
By the other hand, we worked in the optimization of the production cycle of two species of insect: the Acheta domesticus and Hermitia illucens. In both cases, larvae were feed experiment with plant products and by-products from agriculture sector. Insect meal analysis showed a difference in terms of protein and lipid composition. Acheta domesticus showed a higher protein content (> 60%) and fat (<24%) with a good amino acid profile, including tyrosine, alanine and glutamic acid. Linoleic, oleic and palmitic acids.
The obtained results allowed us to make technical decisions on the formulation and the manufacturing of 4 diets for meagre (Argyrosumus regius) and Rainbow trout (Oncorhynchus mykiss) based on a substitution of fish oil and fish meal with the generated products. Fish trial will be carried on within 2020.
ALTERNFEED is funded by Fondacion Biodiversidad, the Ministry for Ecological Transition, through the pleamar Program, co-financed by the FEMP.