Academic Editor: Leonel Pereira
Background: The aim of this work was the study of the proximate composition and profile of fatty acids, minerals, and some microbiological aspects of four edible seaweed species (Chondrus crispus, Palmaria palmata, Porphyra sp., and Ulva sp.) available in the Portuguese market for food consumption, and produced in a national Integrated Multi-Trophic System (IMTA). Methods: Moisture, ash, and total lipids were determined gravimetrically. Crude protein was analysed by Duma’s combustion procedures. The total carbohydrate content was assayed by the phenol/sulphuric acid method. The assessment of the fatty acids methyl esters (FAMEs) was determined through GC-MS. Characterization of elemental analysis was performed by ICP-AES. Different standard microbiological methods were applied for microorganisms. Statistics were performed using the non-parametric Mann–Whitney U test to assess significant differences between samples. Results: Lipid contents (n = 3) were very low (1.6–2.3%), particularly in Palmaria palmata, and Chondrus crispus (1.6–1.7%). The protein content (n = 4) varied from 14.4% in P. palmata to 23.7% in Porphyra sp. Carbohydrates (n = 3) were the major constituent of most seaweeds (31–34%), except in Porphyra sp., with higher content in proteins than carbohydrates. Regarding the fatty acid content (n = 4), in general, saturated fatty acids (SFAs) were the most abundant followed by polyunsaturated fatty acids (PUFAs) and monounsaturated fatty acids (MUFAs). Among macro and trace elements (n = 3), Chondrus crispus shows the highest average content in Zn (71.1 mg
Seaweeds are considered a potential source of non-animal food ingredients of the future, being envisaged as a relevant alternative due to their ability to grow without using arable land or freshwater resources, thus not competing with traditional terrestrial crops . Furthermore, seaweeds take advantage due to their higher growth rate, carbon-neutral emissions, and capability to synthesize a wide range of bioactive compounds  with potential health benefits .
In recent years, the culture and marketing of seaweeds and their products worldwide have attracted growing attention . The global seaweed market size was valued at USD 16.6 billion in 2020 and is expected to show an estimated compound annual growth rate (CAGR) of 10.8% from 2021 to 2028 . Currently, 97% of the world’s seaweed production correspond to seaweed from aquaculture, with only 3% resulting from harvesting/exploitation of wild populations [4, 6]. Among the diverse cultivation methods, Integrated Multi-Trophic Aquaculture (IMTA) offers many advantages. The IMTA system allows combining several species of different trophic levels (e.g., salmon with seaweeds), where the by-products of one species are recycled and become a source of nutrients for another species [7, 8, 9]. The efficiency of these systems is based on the assimilation of excreted ammonium, phosphates, and CO
The green seaweed (Chlorophyta), Ulva sp. (Linnaeus, 1753) (Sea lettuce; Ulvales, Ulvaceae), and red seaweeds (Rodophyta) Chondrus crispus (Stackhouse, 1797) (Irish moss; Gigartinales, Gigartinaceae), Palmaria palmata ((Linnaeus) F. Weber & D. Mohr, 1805) (Dulse; Palmariales, Palmariaceae) and Porphyra sp. (C.A. Agardh, 1824) (Nori; Bangiales, Bangiaceae) were purchased from ALGAplus, Ltd. (Ílhavo, Portugal), a company specialized in the production of seaweeds in a land-based Integrated Multi-Trophic Aquaculture (IMTA) (see Fig. 1). The dry algal biomass (Tok de Mar®) were lyophilized, without any other previous treatment or washing procedure, in a laboratory freeze-dryer (ScanVac Cool Safe 4 L, LaboGene, Denmark), operating at a working temperature of – 50 °C under a pressure of 0.0005–0.002 mBar, for 48 h. Then, seaweeds were milled to less than 1.0 mm particle size using a blender (Orbegozo BV 9600, Murcia, Spain), vacuum-packaged (Sammic SU-316G, Azkoitia, Spain) in labeled polypropylene bags (90
Representative images of red seaweeds (Rodophyta) and green seaweed (Clorophyta). (a) Dehydrated seaweed Dulse (Palmaria palmata). (b) Dehydrated seaweed Nori (Porphyra sp.). (c) Dehydrated seaweed Sea lettuce (Ulva sp.).
The moisture content (MC) was determined gravimetrically by measuring sample (3 g) weight loss at 105 °C in a drying oven (Termaks AS® TS 9135, Bergen, Norway) until constant weight (typically 24 h). Three measurements (replicates) were made on each sample. MC was calculated by using the Eqn. 1:
The ash content (AC) was assessed gravimetrically in triplicate by determining sample (3 g) weight loss in a laboratory muffle furnace (LV 15/11/P320, Nabertherm GmbH, Bremen, Germany), at 550 °C until constant weight. The AC was quantified as the residue from combustion expressed as a percentage of dry weight (% D.W.).
The gravimetric assay was adapted from the method previously described by Kumari et al. . Briefly, to 500 mg of dry seaweed powder 3.0 mL of a mixture of chloroform/methanol/50 mM phosphate buffer pH 7.4 (Honeywell, Germany; Fisher Scientific, UK) in the proportions of 2:1:0.8, v/v/v was added, vortexed for about 1 min and centrifuged (Domel, Centric 150, Slovenia) at 2057
Crude protein content was determined using an FP-528 combustion N analyser (LECO Corporation, St. Joseph, MI, USA). Briefly, 100 mg of each sample is placed into the loading head of the analyser, where it is sealed and purged of any atmospheric gases. Thereafter, the sample is dropped into a hot furnace and flushed with pure oxygen for very rapid combustion, being covalently bound nitrogen (N) converted into nitrogen gas (N
The assay was carried out according to the procedure previously described by Kostas et al. . In brief, 30 mg of each sample were added to 15 mL centrifugal tubes (Deltalab, Barcelona, Spain). Then, 1 mL of 11 M sulfuric acid (Honeywell International Inc., Germany) was added to each tube and incubated at 37 °C for 1 hour on a digital dry bath (AccuBlock™, Labnet International, Inc., NJ, USA). Next, 10 mL of deionized water was added to each tube to have a final acid concentration of 1 M, followed by new incubation (100 °C for 2 h). Afterward, 50
The seaweed samples (10 g each) were homogenized with 50 mL of distilled water and the pH was determined in triplicate using a digital pH meter (Nahita Model 903, Auxilab S.L., Beriáin, Spain) equipped with a glass electrode (XS Sensor Food S7, XS Instruments, Carpi, Italy) and each sample was measured in triplicate.
Seaweed fatty acids methyl esters (FAMEs) were prepared according to the methodology previously described by Kumari et al. . Briefly, to 500 mg of powdered dried sample was added a mixture of 5 mL of acetyl chloride (Sigma-Aldrich®, Germany) and methanol (Fisher Scientific, UK) reagent in a ratio of 1:19 (v/v), spiked with 10
Gas chromatography-mass spectrometry (GC-MS) analysis of FAMEs was carried out on a GC-MS 6850 coupled with 5975C VL MSD (Agilent Technologies, Santa Clara, EUA), equipped with an autosampler G45134A (Agilent Technologie, Santa Clara, USA), using a non-polar fused silica capillary column, 30 m, 0.25 mm ID, 0.25
The seaweed samples were digested and analysed according to a procedure previously described by US EPA . Briefly, 250 mg was weighed and digested in 5 mL concentrated nitric acid 65% (Merck, KGaA, Germany) and 1 mL of hydrochloric acid 37% (Honeywell, Germany), for 48 h using 15 mL Falcon tubes (DeltaLab, Spain). Therefore, the mixture was placed in a fluoropolymer PFA (perfluoroalkoxy alkanes) microwave vessel, sealed, and heated in a microwave until complete digestion.
After cooling, 100
Elemental analysis was performed by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) using an Ultima (Horiba Jobin Yvon, France) model. A calibration curve was made for each element. Major mineral elements were expressed as grams per kilogram of dry weight (g
Samples were prepared in a horizontal laminar airflow cabinet (Aeolus H, Telstar®, Terrasa, Spain) for the purposes of microbial analysis. Each sample (10 g or 25 g) was weighed (Radwag®, Model PS 450/X, Bracka, Poland), taken aseptically, and placed in a BagLight PolySilk sterile blender bag (Interscience, Saint-Nom-la-Bretèche, France) and homogenized with 90 mL of quarter-strength Ringer’s solution (Biokar Diagnostics, France) at room temperature. After 90 s in a stomacher apparatus (BagMixer® 400 P, Interscience, Saint-Nom-la-Bretèche, France), appropriate serial dilutions in sterile ¼ strength Ringer solution were spread-plated (100
Aerobic mesophilic bacteria (AMB) were determined on plate count agar (PCA; Biokar Diagnostics, France), and lactic acid bacteria (LAB) on De Man, Rogosa & Sharpe agar (MRS broth; Biokar Diagnostics, France), acidified to a final pH of 5.4
Yeasts and moulds were grown on chloramphenicol glucose agar (CGA; Biokar Diagnostics, France) after incubation at 25 °C for 5 days. Marine bacteria were determined on marine agar (Condalab, Madrid, Spain) and incubated at 20–25 °C for 72 h. Salmonella spp. was enumerated on Buffered Peptone Water (BPW), Rappaport-Vassiliadis Soja (RVS) Broth (RAP), Muller-Kauffmann Tetrathionate-Novobiocin (MKTTN) broth, Xylose Lysine Desoxycholate (XLD) agar, and Brilliant Green Agar (BGA) (Biokar Diagnostics, France). Listeria monocytogenes were enumerated on Half-Fraser Broth, Fraser Broth, and Palcam Agar (Biokar Diagnostics, France), both incubated at 37 °C for 5 days. The results were expressed as the logarithm of colony-forming unit per gram of sample (Log CFU
Statistics were carried out using the non-parametric Mann–Whitney U test to assess for any significant differences, since statistical assumptions were not met to perform parametric tests. In all cases, the criterion for statistical significance was p
In the analysed seaweeds, MC ranged from 9.7
|Chondrus crispus||Palmaria palmata||Porphyra sp.||Ulva sp.|
|Moisture (% D.W.)||12.2
|Ash (% D.W.)||26.0
|Lipids (% D.W.)||1.7
|Proteins (% D.W.)||15.7
|Carbohydrates (% D.W.)||32.5
|Values presented as mean
The AC ranges from 13.9 to 26.0% D.W. (Table 1), showing a significant difference among all samples (p = 0.0495) except between C.crispus vs P. palmata (p = 0.2752) (Supplementary Table 1). Similar values to C. crispus (~26%) were found by Rupérez and Saura-Calixto  in samples from Algamar C.B., Redondela, Pontevedra, Spain (21.4
Concerning Porphyra sp., Cofrades et al.  found a similar value (11.7% D.W.) for the sample supplied by Algamar C.B. (Redondela, Pontevedra, Spain). While others showed slightly higher values of Porphyra sp. (P. tenera and P. umbilicalis) from different regions of Europe, ranging from 17.2 to 28.2% D.W. [20, 23, 25, 28].
The AC of Ulva sp. (25.5% D.W.) was higher than that reported by Wong and Cheung  and Yaich et al.  for U. lactuca, namely, 21.3% D.W., and 19.6 w/w % D.W., respectively. In addition, in this study, the AC content of the Ulva sp. was lower when compared to U. lactuca from the West Algerian coast (27.1% fresh alga) , and seaweeds off the coast of Norway (29.3% D.W.) . As noted previously, the AC can vary widely between species, geographical regions, and even between seasons . The high AC are an important feature of seaweeds, and generally are much higher than those observed in terrestrial plants [3, 25, 30, 31].
The total lipid content of the seaweeds ranges from 1.6 to 2.3% D.W. (Table 1), showing significant differences (p = 0.0495) among samples (C. crispus vs Ulva sp., P. palmata vs Ulva sp., and Porphyra sp. vs Ulva sp.) (Supplementary Table 1). Most seaweeds show a very low lipid content ranging from 0.3–7.0% D.W. [30, 32, 33], thus being a low source of nutritional energy when compared with some plant vegetables such as soy or sunflower . Similar results were reported for C. crispus (0.7–2% D.W.) and Porphyra spp. (1.3–2.3% D.W.) by Soares et al. . Other researchers such as Mæhre et al.  reported 2.6% D.W. for Ulva lactuca, a value that is in agreement with those found in the present study. As described by Soares et al. , in most cases commercial seaweeds show higher values than wild seaweeds. According to some authors the lipid content of seaweeds can vary according to species, geographical location, climate, and environmental conditions such as temperature, light intensity, salinity, and nutrient content of the growth medium and either to species types and/or a combination of these factors [28, 36, 37].
Protein is a major factor when assessing the health benefits of a food product . It is an important source of sulfur (S) and nitrogen (N), essential components of organisms that are not produced in the human body, being also essential precursors for the synthesis of several biomolecules . Given an N-to-protein conversion factor of 5, the total protein content in the samples studied was estimated between 14.4 and 23.7% D.W. (Table 1). Statistical analyses revealed significant differences among all seaweeds (p = 0.0180), except for C. crispus vs Ulva sp. (p = 0.2367) (Supplementary Table 1), which is within the range reported by Sánchez-Machado  for seaweeds collected on the northwest Iberian coast, and also by Paiva et al.  for seaweeds collected in the Azores Archipelago. Some authors reported higher values for C. crispus (20.9% D.W.) and Porphyra (29.8% D.W.)  for commercial seaweeds (Algamar C.B., Redondela, Pontevedra, Spain).
Concerning P. palmata, its total protein content is in the range of 8–35%, with most typical values around 20% . In general, protein content differs widely across groups of seaweeds , and this can be explained through variances attributed to different species, environmental factors, or a combination of both [28, 30, 41], or even by methodological differences .
Seaweeds, especially the red seaweeds, appear to be an interesting potential source of food proteins as demonstrated by some authors [30, 42]. Some of them, especially Porphyra spp. have a protein content higher than those found in high-protein pulses such as soybean [20, 23, 25]. In general, specific seaweeds present higher protein contents than some grains such as rice (7.1%), corn (9.4%), oats (13.4%), or even wheat (13.8%) .
Carbohydrates comprise 50–60% of the dry weight of seaweeds . The carbohydrate content (CC) of the seaweeds analysed in this study ranged from 19.8–34.0% D.W. (Table 1), making it the largest constituent on a dry weight basis, the only exception is Porphyra sp. In general, the values encountered for CC are out of the range of values reported by several authors in red seaweeds [24, 28, 43]. Statistical analyses showed significant differences between C. crispus vs Ulva sp., P. palmata vs Ulva sp., and Porphyra sp. vs Ulva sp. (p = 0.0495) (Supplementary Table 1). Concerning Ulva sp., the values observed were higher than those reported by El-Said and El-Sikaily  for seaweeds collected along the Egyptian Mediterranean coast, where concentrations in Ulva lactuca varied from 10.2–11.5% D.W. However, Olsson and Albers  reported a CC to U. lactuca (34.7% D.W.) and to U. intestinalis (36.7% D.W.) collected on the Swedish west coast comparable to those found in the present study. According to some authors, the seaweed’s carbohydrate synthesis is related to periods of maximum growth, increased rates of photosynthetic activity, and a reduction in protein contents [28, 45, 46].
In this study, only Porphyra sp. presents an inverse relationship between protein and carbohydrates; a pattern observed for several species of seaweeds . The carbohydrate synthesis is favoured by light intensity, temperature, and decrease of nitrogen, while for the proteins these parameters are inversely related [46, 47].
The pH values ranged from 6.2
The variation in pH values can be important since pH is indicative of enzymatic or microbiological activity linked to quality, freshness and safety of foods . It is also a factor of great importance for the storage of the product before further use . For instance, pH linked to other parameters such as the percentage of exudate and changes in colour and texture indicate a loss of seaweed freshness associated with the increase in micro-organisms [48, 50]. The results obtained in the present study are close to neutral and, therefore, makes seaweeds potentially vulnerable to microorganisms .
The results of FAMEs are shown in Table 2. As can be seen, the species variability is quite evident in the FAMEs composition. These variations could be due to genetic differences among species, as well as other abiotic factors (e.g., light, salinity, and nutrients) [25, 31]. On other hand, variations can also be due to factors such as environmental and seasonal conditions at the time of planting and harvesting [51, 52].
|Fatty acids (FAMEs)||Group||Abbrev.||Seaweeds|
|Chondrus crispus||Palmaria palmata||Porphyra sp.||Ulva sp.|
|Results expressed as a percentage of total fatty acid analysed. Values are given as mean
The saturated fatty acids (SFAs) were the most abundant FA, ranging from 43.2 to 86.2% of the total FA for the Porphyra sp. and P. palmata, respectively. These results agree with studies previously reported by Mæhre et al. , who found that SFAs were the main FA in seaweeds. The statistical analyses revealed significant differences among all samples (p = 0.0180) (Supplementary Table 3).
Concerning unsaturated fatty acids (UFAs), significant differences were observed among all seaweeds (p
PUFA/SFA ratios presents significant differences among all seaweeds (p = 0.0180) (Supplementary Table 3), and values ranged from 0.4 to 1.14, which is in accordance with the nutritional guidelines recommendations (
|Elements||C. crispus||P. palmata||Porphyra sp.||Ulva sp.||C. crispus||P. palmata||Porphyra sp.||Ulva sp.|
|Intake (g)||RNI (%)||Intake (g)||RNI (%)||Intake (g)||RNI (%)||Intake (g)||RNI (%)||Adults|
|Values are presented as mean
In general, the mineral content of seaweeds is relatively higher than that of the most edible land plants . C. crispus showed the higher content in Na (8.0
Sodium (Na) and potassium (K) were the most abundant elements among seaweeds. According to some authors, the contents of Na and K in Chlorophyta Ulva spp. tend to be lower when compared with red and brown seaweeds [59, 60]. Likewise, P. palmata collected in Portugal presents high amounts of K . Sodium (Na) results showed significant differences among all samples (p = 0.0495) (Supplementary Table 4), and are not in agreement with data previously reported by other authors. For example, the results are lower for C. crispus with values 4–6 times below the values reported by Olsson and Albers  and Parjikolaei et al. . The same was determined by several authors for Porphyra sp. in different seawaters over the world [20, 28, 62]. However, results comparable to those obtained in this study were determined by Larrea-Martín et al.  in Eastern Porphyra purchased in the Spanish local market (but imported from Asian countries), which registered 2.3 g
Concerning K, significant differences were observed among all seaweeds (p = 0.0495) (Supplementary Table 4). Seaweeds contain a high content of K (higher than fruits or vegetables), which has been reported to protect against high blood pressure and other cardiovascular diseases when intake levels are high [3, 64]. Some seaweed accumulates more K than Na , which is quite evident in the present results, especially in C. crispus (41.0:8.0 g
Na/K ratio show significant differences among all seaweeds (p = 0.0495) (Supplementary Table 4). Altough when compared with other reports they show lower ratios . However, it has been reported that a molar Na/K ratio of
The mean P content ranged from 1.1 to 2.1 g
The present results of Mg show significant differences among all samples (p = 0.0495). Values of red seaweeds range from 2.5 to 6.5 g
Even seaweeds with lower levels of Mg, such as Porphyra sp. (3.7
The seaweeds analysed in this study can contribute 6.6–17.3% of the Mg RNI (Reference Nutrient Intake) for adults. With the exception of Ulva sp. with a supra-high percentage of almost 150%.
Calcium (Ca) content differed significantly among all seaweeds (p = 0.0495), except in P. palmata vs Porphyra sp. (p = 0.5123) (Supplementary Table 4). The lowest mean Ca concentration (1.6 g
Iron (Fe) was the trace element with the highest concentration detected in the analysed seaweeds, ranging from 43.5 to 336.4 mg
The Zn concentrations show significant differences between all samples (p = 0.0495) except for P. palmata vs Ulva sp. (p = 0.2752) (Supplementary Table 4), with C. crispus (71.1
Seaweeds are a highly perishable foodstuff, and because of their high moisture level, apart from a richness content in nutrients, are an excellent promotor of microbial growth . In addition, several bacterial species, including Salmonella spp., Escherichia coli, Listeria spp., or Staphylococcus aureus could pose significant hazards, since microbial contamination can occur during the growth cultivation, harvest environment, or further processing as post drying handling [73, 74]. Microbial growth (Log CFU
|Microbiological parameters (Log CFU·g
|C. crispus||P. palmata||Porphyra sp.||Ulva sp.|
|Salmonella spp.||Absent in 25 g||Absent in 25 g||Absent in 25 g||Absent in 25 g|
|Listeria monocytogenes||Absent in 25 g||Absent in 25 g||Absent in 25 g||Absent in 25 g|
|Counts, expressed as Log CFU
Salmonella spp., a non-spore-forming Gram-negative bacteria, was not detected on any sample (not present per 25 g), prompting the conclusion that these results fit in the Portuguese guidelines on the application of general principles of food hygiene to the control of Salmonella spp. in ready-to-eat foods by INSA (Instituto Nacional de Saúde Doutor Ricardo Jorge) . Listeria monocytogenes were not detected through plating count (not present per 25 g), which is in line with results obtained by Blikra et al. .
No significant differences were observed for Enterococcus (p = 1.000) (Supplementary Table 5). Enterococcus can be used as indicators of faecal contamination . This genus can be present in heterogeneous habitats due to its capacity to grow under low water activity (a
Concerning LAB, moulds, yeasts, and S. aureus, the values obtained do not exceed the limits of the food quality standards summarized by INSA . Positive values for AMB were encountered in all seaweeds, with P. palmata (4.9 Log CFU
Marine agar counts (MAC) ranged from 3.7 Log CFU
Concerning E. coli, significant differences were detected between C. crispus vs Ulva sp. (p = 0.0082), P. palmata vs Ulva sp. and Porphyra sp. vs Ulva sp. (p = 0.0126) (Supplementary Table 5). Results indicate the absence or very low numbers of colonies (
The results of the present study indicate that the analysed seaweed species can be used as functional foods or food ingredients in many healthy low-fat foods to improve the nutritional quality and functionality of foods products, in general, enhancing a healthy balanced human diet.
Although there are studies with some similar results, the present study suggests that the composition and content of seaweeds varies, possibly according to several factors (e.g., season, geography, geological nature of the site). Thus, this study shows seaweeds with some distinctive features, mainly because they provide amounts of some compounds and elements different from those reported in other studies.
C. crispus, P. palmata, and Ulva sp., showed to be a rich source of minerals and trace elements with potential for use in sodium chloride replacement. On the other hand, seaweeds can serve as a food supplement to help meet the recommended adult daily intake (RDI) of several macro and trace elements, contributing with some elements that are normally scarce or even absent in some terrestrial foodstuffs and reducing the impact of some pathologies associated with the modern lifestyle. All seaweeds showed a very low lipid content, thus being a low source of nutritional energy. In the other seaweeds analysed, they showed a high-quality fat, comprising a relatively higher level of SFAs. Porphyra sp. and Ulva sp. were rich sources of UFAs, suggesting that they can be used to reduce the risk of cardiovascular disease. In addition, seaweeds, especially Porphyra sp., can be a protein-rich species compared to terrestrial foods, may be useful as a complementary source of dietary proteins for human nutrition. Overall, the results highlight the potential of using seaweeds as an alternative and sustainable source of proteins, but also elements (e.g., Mg, Zn, Fe) with benefits for human nutrition and industrial food processing. The microbiology analyses revealed that analysed seaweeds can be used as a raw material for food for human consumption. As a concluding remark, this study contributes to a comprehensive understanding of the use of available edible seaweeds available in the Portuguese food market but also in the European and global market.
AC, ash content; AMB, aerobic mesophilic bacteria; BGA, brilliant green agar; BP, Baird-Parker; BPW, buffered peptone water; CAGR, compound annual growth rate; CFU, colony-forming unit; CGA, chloramphenicol glucose agar; CRMs, certified reference materials; DM, dry matter; D.W., dry weight; EDTA, ethylenediaminetetraacetic acid; FA, fatty acid; FAMEs, fatty acids methyl esters; GC-MS, gas chromatography-mass spectrometry; GYP, glucose-yeast-peptone; ICP-AES, inductively coupled plasma-atomic emission spectrometry; ID, internal diameter; IMTA, integrated multi-trophic aquaculture; LAB, lactic acid bacteria; MAC, marine agar counts; MC, moisture content; MKTTN, Muller-Kauffmann tetrathionate-novobiocin; MRS, de Man, Rogosa & Sharpe; NIST, national institute of standards and technology; PCA, plate count agar; PFA, perfluoroalkoxy alkanes; RNI, reference nutrient intake; RPF, rabbit plasma fibrinogen; RVS, Rappaport-Vassiliadis soja; SD, standard deviation; SFA, saturated fatty acid; TAG, triacylglycerides; UFA, unsaturated fatty acid; USD, US dollar; XLD, xylose lysine desoxycholate.
The idea of research was suggested by MSD and PM. ER provided help and advice on experimental analysis of carbohydrates, fatty acids, lipids, and elemental analysis. Protein analysis was done by IM. MM-F provided help in microbiological assays. Statistical analysis and the experimental process were guided by BMC. The writing of the manuscript was done by BMC, MSD, PM and JPN. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript.
This research was performed under the Alga4food project funded by the European Maritime and Fisheries Fund and co-financed by the Operational Program MAR2020 in the field of Sustainable Development of Aquaculture in the domains of Innovation, Advice and Productive Investment – Innovation and knowledge Action, grant number MAR-01.03.01-FEAMP-0016 – Alga4Food. This research was also supported by the Applied Molecular Biosciences Unit (UCIBIO) and the Associate Laboratory for Green Chemistry (LAQV), both funded by national funds from FCT/MCTES (UIDB/04378/2020) and (UID/50006/2020), respectively, and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER - 007265).
The authors declare no conflict of interest.