Production of vegetable protein concentrates by micronization and grain size separation in airflow: applications in aquaculture
University of Trás-os-Montes and Alto Douro (UTAD); Sparos Lda.; Esteve Santiago S.A. (ESASA)
Aquaculture assumes a vital role as a source of fish to meet the growing needs of the human population. A responsible development of this industry should be based on the balance between quality and food safety, the environmental impact of production systems and taking into account any socio-economic implications. Several species of aquaculture fish, such as salmon, trout, sea bream or sea bass, are considered carnivorous. In captivity, these species are fed with diets rich in protein and fat and derived from ingredients of marine origin, such as flours and fish oils. Reducing the inclusion of these ingredients of marine origin in fish feed is one of the greatest challenges today for the future sustainability of aquaculture. Promoting the use of sustainable ingredients in the diets of these animals, by replacing flour and fish oil with ingredients of plant origin (e.g. soy, corn, wheat, lupine, etc.) is one of the research priorities at European level. However, the incorporation of high levels of traditional plant proteins (soy, corn, wheat, lupine, among others) results in a reduction in fish growth performance, generally associated to lower protein digestibility, lower food appetite, possible imbalance in the amino acid profile, the elevation of the fiber level and the presence of anti-nutritional factors (ANF). In this context, the development of protein concentrates of plant origin with increased nutritional value (e.g. high protein digestibility, elimination of FANs) is a valid solution and already successfully tested in fish. However, the costs associated with the traditional processes of separation and concentration of the protein fraction (aqueous extraction and / or with organic solvents) make these products too expensive for the animal production sector. An interesting alternative for the production of protein concentrates is the innovative use of a "dry" process, based on micronizing techniques and gravimetric classification under a continuous airflow. The EUPROTEINAQUA project aimed to develop plant protein concentrates from European cultures of lupine, corn, broad bean, peas and rapeseed using the innovative association of a spraying / micronizing process for protein and starch fractionation and subsequent gravimetric separation in continuous airflow. In addition to the implementation of the new technological process, the project also aimed at the analytical characterization of protein concentrates in terms of anti-nutritional factors and the validation of their biological efficacy in fish (trout and sea bream) feeding.