Introduction
Fish is a known healthy alternative to meat due to its high-quality proteins and protective omega-3 fatty acids. Also, the benefit of vitamins and minerals loads, increases the importance of fish in our diet. As aquaculture needed to keep up with the high demand for fish , tailored diets are paramount for a robust, healthy fish, that grows fast to fulfill consumers’ expectations . It is common to add trace amounts of specific additives to fish diets to improve the quality of feed aiming mainly to increase health performance, fish feeding efficiency and flesh quality. Fish feed additives may also be an alternative to fulfill the consumer’s health needs such as decreasing the allergenicity of fish products through modulation of specific proteins.
Allergies to fish are a growing health concern worldwide and avoiding fish (products) is still the only option to prevent severe reactions such as rash and anaphylaxis. It is known that 95% of allergic reactions are due to a white muscle protein called β-parvalbumin. This calcium-binding protein might be modulated with the inclusion of specific molecules in fish diets. Creatine and EDTA are known to be involved in reducing the intracellular calcium content and in chelating calcium ions, respectively. Creatine might then act as a modulator of β-parvalbumin expression while EDTA might induce a rearrangement in the 3D- structure of this protein , both aiming the reduction of its allergenicity . Previous work by our group showed a biological reduction in fish allergenicity upon a 3% EDTA supplemented diet. The present work aimed to contribute to a better understanding of the effects of dietary creatine or EDTA supplementation levels, aiming in reducing fish allergenicity, on European seabass flesh quality that would meet consumer’s expectations.
Methodology
Two independent feeding trials with juvenile European seabass were performed at the Ramalhete experimental station (CCMAR/University of Algarve, Portugal) . Fish kept in 500L tanks were fed with a commercial feed vs supplemented diets with Creatine (2% vs 5% vs 8%) or EDTA (1.5%, vs 3% vs 4.5%) under natural environmental conditions (dissolved oxygen above 5 mg L-1 ). Initial body weight of the fish were 186 ± 0.83 g and 174 ± 1.29 g , for the creatine and EDTA trial, respectively. After three months of ad libitum feeding (twice a day), fish were killed by ice slurry and sampled for flesh quality through inspection of texture and sensorial analysis.
Results
At the end of each trial, the edibility of fish was determined by a trained sensorial panel that performed tests on steamed fillets attributing points to different parameters (i.e., taste, firmness, succulence). Also, texture properties (i.e., hardness, springiness, and chewiness, between others) was determined mechanically and shown in Table 1. Both quality parameters (sensorial and texture) showed no significant differences between diets in both trials (p>0.05).
Conclusion
Dietary supplementation with Creatine (up to 8%) and EDTA (up to 4.5%) preserved European seabass quality and edibility. Nutritional strategies like diet supplementation with specific traced molecules amounts, are a promising avenue to tailor fish for Human consumption without jeopardizing consumer’s expectations.
Acknowledgements
This work received Portuguese national funds from FCT- Foundation for Science and Technology through project UID/04326/2020. This work integrates project 16-02-01-FMP-0014- Allyfish co-financed by Mar2020 (4107IDNAD50308.18). DS, CRM and RC acknowledge FCT for PhD scholarships (SFRH/BD/136319/2018, SFRH/BD/138884/2018 and 2021.06786.BD).