Nutritional evaluation of two marine microalgae as feedstock for aquafeed

Abstract

Using microalgae for animal nutrition provides an economically viable route for microalgae-based technological innovation, especially in combination with CO 2 fixation given current global warming. However, this technology still lacks sufficient evaluation for screening microalgae for specific animals; meanwhile, current studies show some prejudice regarding 'essential' or 'non-essential' ingredients. The results show that Dunaliella salina and Nannochloropsis salina were able to accumulate high protein (30%-57%) and lipid (20%-46%) content without affecting the performance of CO 2 fixation, which reached 0.28 and 0.23 g L −1 day −1 respectively. Both species exhibited high quality of lipids and proteins for Penaeus monodon based on the profiling. The essential fatty acid indexes (EFAI) for N. salina and D. salina were 3.81 and 9.02 respectively. Butyric acid was found to be present in both D. salina (12.03%) and N. salina (4.87%) based on the total fatty acids (FAs). The essential amino acid indexes (EAAI) for D. salina and N. salina were 2.23 and 1.29 respectively. Arginine was the most abundant essential amino acid (EAA) in both D. salina (10.83%) and N. salina (13.35%) on the basis of total amino acids (AAs). This study comprehensively compares the nutritional quality of the two commercial marine microalgae of D. salina and N. salinawith the potential to be used as sustainable sources of lipids and proteins to reduce or even replace the traditional fish oil and fish meal in aquafeeds. K E Y W O R D Samino acid, aquafeed, fatty acid, lipid, microalgae, protein | 947 CHEN Et al.

Protein Recovery from Underutilised Marine Bioresources for Product Development with Nutraceutical and Pharmaceutical Bioactivities

“…and Spirulina sp. (44.4% and 43.8%) [15]. Marine fish proteins also have a competitive percentage of EAAs, 45.6% in proteins of finfish species, e.g., yellowfin tuna [149] and 38.9-41% in proteins of crustaceans, e.g., lobster and shrimp [19,150].…”

“…Lysine/arginine ratios have been used for evaluation of the nutritional value of proteins, since consuming proteins with a high ratio causes some lipidemic and atherogenic effects [156]. The very low lysine/arginine ratio of marine proteins, e.g., 0.16-0.42 for microalgal proteins (N. salina and D. salina) [15] and 0.7-1.0 for crustacean proteins (lobster shells and heads) [18,19] compared to 13.8 in meat proteins [157] highlights potential health benefits when including marine proteins in human diets. In addition, fish protein characterised by enrichment with savoury aromatic amino acids together with nonprotein nitrogen compounds (i.e., small peptides, trimethylamine oxide, trimethylamine, creatine, creatinine, and nucleotides) enhances the palatability of a wide variety of foods thereby increasing product potential [158][159][160][161][162].…”

“…They are therefore a hitherto underutilised bioresource for protein recovery. Similarly, protein contents of several marine microalgal species such as Dunaliella salina , D. tertiolecta , Nannochloropsis occulata , Tetraselmis suecica , Tisochrysis lutea (formerly Isochrysis galbana [ 13 ]), and Chlorella stigmatophora commonly range between 25–57% ( Figure 1 ) [ 14 , 15 ]. Production of microalgal biomass can be flexibly conducted indoors or outdoors, depending on climatic conditions, on non-arable land with a minimal competition to conventional agricultural crops [ 16 ].…”

“…Regardless of biomaterial type used for protein production, the obtained products are typically protein concentrates (PCs) or protein hydrolysates (PHs). Enzymatic digestion of the PC and PH are being used as the sole or partial nitrogen source in specialised adult nutritional products and supplements [ 15 , 18 , 19 , 20 ]. Hydrolysis changes the chemical, physical, biological, nutritive, and immunological properties of proteins [ 21 ].…”

Sustainable Aquafeeds: Using Aquafarmer Preference to Inform a Multi-criteria Decision Analysis

“…Aquafeed is one of the main drivers of material and energy flows in aquaculture systems, ascribing to it a significant role with regard to environmental, economical, and technical aspects of aquaculture food production. ,, The contribution of aquafeeds to the overall environmental impacts, economic performance, and production quality of aquaculture systems has been distinctly highlighted and investigated in many recent studies. − Forage-sourced fish meal and fish oil are the traditional main sources of essential nutrients in formulated aquafeeds, making them the major material and energy inflows in aquafeed production . To prevent single-source dependency on a finite resource, there is a growing desire to implement alternative ingredients (to fish meal and fish oil) in aquafeed formulation to achieve acceptable production while mitigating the ecological burdens. − It is necessary to quantify the environmental trade-offs that may occur due to the usage of nonconventional aquafeed ingredients.…”