There is no doubt the aquafeed industry needs to do “more and better” in terms of sustainable use of marine ingredients. Outside price volatility, the sector is facing several major challenges when sourcing marine ingredients: extreme variability in the quality of fish meals; safety concerns with high levels of contaminants (heavy metals, microplastics…); sustainability issues with some poorly managed fisheries. In this context, the limited supply of wild fish stocks should drive the optimization in their process preserving the unrivalled nutritional values of marine ingredients compared to other alternatives. The Fish Protein Hydrolysates (FPH) of BLUE FISH FACTORY in Morocco features many key advantages:
1. Sustainability and Traceability
Pelagic landings in Morocco represent around 85% of the 1.35 million tonnes total landings, with around 65% being sardines (Sardina pilchardus). The pelagic stocks are considered in good condition and as “not fully exploited” (FAO/CECAF/MarinTrust) while Moroccan authorities implement regular controls and fish stock assessments. At the BLUE FISH FACTORY plant, only by-products of pelagics are used such as discarded batches for technical reasons (visual appearance, freshness grade…); trimmings including heads and viscera. Finally, all raw materials are fully traced up to the fishing boats and controlled by a third party, with under progress certifications including: GMP+, MarinTrust, ISO 22000. It finally ensures the total absence of farmed fish species.
2. Safety and conformity to regulations
Fortunately, pelagics like sardines and mackerels are placed in the mid-low Trophic Level (TL around 3) consuming prey such as copepods (Mounir, 2022). Hence, sardines have a naturally low level of contaminants as described in table 1.
Table 1: Heavy metal values in Blue Fish Factory Fish Protein Hydrolysate
3. High nutritional values of Fish Protein Hydrolysate
Enzymatic hydrolysis method ensures and preserves the full value of marine proteins, being more gentle in terms of temperature compare to the standard fish meal process. The graph 1 describes the content of the Essential Amino-Acid of FPH from sardines compared to vegetable proteins such as Soy. It is also worthwhile to mention the high content of Non-Essential AA such as Alanine, Glycine, Proline which will participate in bioactive peptides or the presence of Taurine, reconsidered as essential for some species with key metabolic functions (Salze, 2015).
Freshness of the by-products should be effective and a reality for pelagics dedicated to human consumption: daily landings to the canneries with no long storage on board including cold storage conditions to prevent spoilage, as detailed in the table 2. Biogenic amines are heat stable while Total Volatil Nitrogen (TVN) by definition considered volatile compounds. TVN is considered mostly under two forms: TMA (Trimethylamine) and ammonia. TMA comes from the microbiota and bacterial growth while ammonia comes from the AA decomposition. Therefore, TVN could be lower in fish meals dried at high temperature. But in hydrolysates, TVN is mostly under the trimethylamine form and might be higher than in fish meals. Recent studies highlight the key role of metabolites such as TMAO in osmoregulation and stress (Mengge, 2023).
Table 2: Biogenic amines and Total Volatil Nitrogen values in Fish Protein Hydrolysate
4. High Protein Solubility and Molecular Weight distribution
“There is increasing evidence that some components present in the water soluble fraction of marine protein sources are important for fish performance, especially in high plant protein/low fish meal diets “(Kousoulaki, 2009). BLEU FISH FACTORY FPH process allows to keep all the soluble proteins within the product. The table 3 details the water protein solubility of various marine ingredients including live food. During the conventional fish meal process, the stick water rich in soluble proteins might be insufficiently collected, concentrated and injected back into the fish cake. Furthermore, harsh drying conditions induce protein denaturation and Maillard reaction. The high content of water soluble protein fractions will clearly enhance the feed palatability in all situations, including the better acceptance of medicated feeds. Protein digestibility coefficient of FPH is considered to be above 95% for most species.
Table 3: Values of Protein Solubility (%) in some marine ingredients
By definition, enzymatic protein hydrolysis consists of the water addition with a selected protease enzyme, for the cleavage of the peptide bonds of large proteins into low molecular weight peptides and free amino acids. The graph 2 compares the average Molecular Weight (MW) distribution of one fish meal to the BLUE FISH FACTORY FPH. It shows significant differences, while FPH is 90% below 5000 Da (average 3,300 Da) with 25% as free AA and di or tri-peptides; the fish meal MW distribution is 90% below 60,000 Da (average 30,000 Da) with no detected free AA.
Molecular Weight distribution is related to the protein water solubility. It correlates also with the higher protein digestibility, meaning faster and easier intestinal assimilation, well assessed for larvae and juveniles.
5. Functional Properties of Fish Protein Hydrolysates
Bioactive peptides are defined “as the fragments of AA sequences in a protein that confer biological functions beyond their nutritional value”. These bioactive peptides are usually 2–20 AA residues in length with frequent presence of some AA such as: Arginine, Lysine or Proline. They have well known properties in fish and shrimp such as: antimicrobial, antioxidant and immunomodulatory activities. FPH from sardines contains specific bioactive peptides which help to sustain animal health against pathogens or reduce the antinutritional side effects of high vegetable diets (Costa et al.,2020).
Conclusion
In the challenging context of sustainability, availability and price, the aquaculture industry needs to improve the quality and processing methods of the unrivalled marine ingredients. Fish Protein Hydrolysates from pelagic species such as sardines or mackerels feature some key technical advantages and offers the opportunity to do “better with less”.
References : All references available upon request
