Polyphenols, found in plants and algae have attracted the attention of the aquaculture sector for the development of innovative and attractive nutritional feeds, especially for their antioxidant and antimicrobial properties. A multitude of studies on the administration of these natural compounds have reported improvement in health, resistance to illness, and oxidative status in different animal production systems, including aquaculture. In the rapidly evolving fish feed industry, the quest for natural antioxidants has led to a pivotal focus on marine-derived bioactive compounds. While terrestrial plant compounds have been well-studied and widely utilized, marine sources such as macroalgae are emerging as a novel and sustainable source of natural antioxidants.
The application of compounds from seaweed as antioxidants in the fish feed industry involves many processes, but as a starting point, there are two crucial aspects to consider: extraction of bioactive compounds from the algae and evaluation of their effect on fish health. There are multiple techniques available for extraction and purification of polyphenols, and several parameters to study, depending on the chosen technique. Nevertheless, the most challenging aspect in the optimization of the extraction is the objective evaluation of the best extracts, with an optimal balance between quantity and antioxidant activity.
The first stage of the project has been focused on the extraction of bioactive compounds, and consisted of exploratory extractions of various seaweed species, searching of industrially applicable methods, using green solvents and focusing on finding the best practices for the efficient extraction of compounds with antioxidant potential. Analytical methods for screening of content of polyphenols and addressing the antioxidant potential of extracts have been standardized for seaweed and preliminary pre-purification steps have been conducted.
The aquaculture sector faces many challenges worldwide, a very important one being the detrimental effects of oxidative stress in fish caused mainly by intensive production practices. Synthetic antioxidants, such as BHT, BHA and, until 2017, ethoxyquin, are used as feed additives to limit lipid oxidation, prevent oxidative losses of microingredients, and stabilize nutrients that are susceptible to critical oxidation. However, there are many safety concerns regarding these synthetic compounds and there is an urgent need to find more natural and healthier alternatives.
Natural antioxidants (NAOX), such as polyphenols, are found in many healthy foodstuffs and have attracted the attention of the aquaculture industry for the development of innovative and attractive nutritional feeds, especially for their antioxidant and antimicrobial properties. Bioactive compounds from marine sources, such as seaweeds, are a promising source of NAOX as they are a readily available resource in Norway, a more natural food source for fish than terrestrial plant alternatives, and provide a unique selection of potent polyphenols. Examples of compounds from seaweeds that have already been reported to exhibit antioxidant properties include; phlorotannins, found only in brown algae, and laminarin, fucoxanthin, and fucoidan. These products are already being marketed, however, the potential of seaweeds as a sources of NAOX is only just being realised and needs warrants much further research.
This project aims to study and optimize the extraction of NAOX from Norwegian seaweeds for use in fish nutrition to improve the oxidative status of the fish. The proposal is divided into 3 work packages:
-Extraction and refinement of the quantity and quality of NAOX from selected species of seaweed
-Develop methods for identification and quantification of NAOX from seaweed
-Functionality testing (evaluating product performance) of a refined NAOX extract from seaweed using in vitro and in vivo approaches.
