Fish is a popular source of healthy protein with high nutritional value, but it is also considered the third most allergenic food in the world. The main allergen in fish is the muscle protein called β-parvalbumin which can exist in two forms; one with chelated calcium ions (Ca2+) in its 3D-structure, and another, called apo-form, which is calcium-free. This apo-form has reduced allergenic activity, and therefore inducing it in fish muscle could be a promising way to produce hypoallergenic fish. Adding fractions of microalgae to fish diets, that were previously identified as rich in calcium chelating compounds, to fish diets could be a viable approach to induce the apo-form of β-parvalbumin and reduce the allergenicity of farmed fish. Microalgae are a sustainable ingredient for fish feed because they can grow by capturing and converting CO2 into biomass, reducing the carbon footprint, and mitigating global warning. They can also be grown using wastewater, supporting the circular economy. Besides their rapid growth rate, microalgae have the right blend of proteins, lipids, and carbohydrates, are rich in omega-3 fatty acids, antioxidants, and have a well-balanced amino acid profile. The main objective is to identify the best extraction protocol to obtain microalgal extracts with high calcium chelating activity, formulate microalgae supplemented fish diets, and produce gilthead seabreams with lower allergenicity.
Freeze-dried algal biomass of Nannofrustulum shiloi was obtained from NECTON S.A. (Olhão, Portugal). Extracts were obtained using an automated solvent extraction system (EDGE, CEM Cooperation) using 1 g of biomass and ethanol as solvent with different extraction conditions (volume, temperature, and time), and the extracts analysed for calcium chelating activity (CCA) and extraction yield (Table 1). The CCA was determined in 96-well plates, following the protocol by (Silva et al. 2022). The best extraction protocol was chosen and microalgae extract will be supplemented in fish diets. The nutritional trial will be performed on juvenile gilthead seabream (150 g), and muscle samples will be collected and analysed for IgE reactivity using fish-allergic patient sera.
This approach represents a unique and promising avenue to address the growing concern of fish allergies among the general population. The perspective of this work is a sustainable production of non-genetically modified hypoallergenic fish as a smart and safe food.
Silva, M., et al. 2022. “Microalgae as Potential Sources of Bioactive Compounds for Functional Foods and Pharmaceuticals.” Appl. Sci. 12 (12).