Microalgae unveil their potential, up front 'nutrition and health', also thanks to their ability to produce bioactive substances such as astaxanthin, a carotenoid with extraordinary antioxidant power. Its intended uses are multiple, come on functional foods and food supplements to cosmetics and medicines, up to aquaculture and animal husbandry.
The microalgae haematococcus pluvialis it is the species of greatest economic interest for the production of natural astaxanthin, even if other species of microalgae (accompanied by yeasts and bacteria) can also be used for the extraction of this precious ingredient (or additive, depending on the uses). (1) A deepening.
1) Natural and synthetic astaxanthin
Astaxanthin it is a carotenoid known for its reddish color and its extraordinary antioxidant properties, far superior to those of other molecules such as vitamins C and E, lutein and β-carotene. The microalgae haematococcus pluvialis (o H. lacustris) is the first natural source of astaxanthin, whose production costs are not competitive with those of chemical synthesis of the same molecule. Synthetic astaxanthin is therefore very popular in the feed sector (outside organic supply chains), but its use in food and food supplements is not authorized in the EU.
The substantial differences (advantages and disadvantages) between natural and synthetic astaxanthin are identified as follows:
- natural astaxanthin has a markedly superior bioactivity and antioxidant power, greater safety of consumption, lower environmental impact. With the disadvantages of higher production costs, lower yields and lower shelf life,
- its synthesis replica has antithetical characteristics. And therefore low production costs, high availability, greater stability, but also a serious environmental impact due to the use of petrochemical reagents and complex, non-renewable biosynthesis pathways.
2) Astaxanthin from microalgae, the protagonists
The precious carotenoid can be extracted from some fish species (e.g. krill oil, crustacean exoskeletons) or, in the versions vegan, by some microalgae and microorganisms. EFSA, in recognizing a haematococcus pluvialis lo status di QPS extension (Qualified Presumption of Safety), indicates it as the first source of astaxanthin. Compared to other microalgae – like Chromochloris zofingiensis e Chlorococcus spp., Botryococcus braunii – but also with respect to the microorganisms from which it can be obtained (see par. 4).
3) Chromochloris zofingiensis, a revolutionary microalgae
Chromochloris zofingiensis (already known as Chlorella zofingiensis) is a green microalga candidate to replace haematococcus pluvialis (lacustris) just to extract astaxanthin. In fact, it has a faster biomass multiplication and production capacity, especially in conditions of particular environmental stress.
The extraction and carotenoid recovery (ie downstream processing) are in turn easier, thanks to a higher efficiency of cell wall destruction and metabolite separation. With the only limit of a lower production yield of astaxanthin per cell volume and total biomass.
Stress conditions induced through high light irradiations, stimulated by blue LEDs (not to be administered in excess, in order to avoid metabolic blocks) and white fluorescent lamps have proved to be optimal for stimulating the bioaccumulation of astaxanthin in C. zofingiensis (max 39.8mg/L). In order to further increase productivity, cell density, nitrogen concentration, as well as the type and intensity of light radiation will also have to be considered in the future. (2)
4) Alternatives to microalgae
Microorganisms such as yeasts and bacteria can also be used to produce natural astaxanthin. Between these:
- Phaffia rhodozyma/Xanthophyllomyces dendrorhous. Asexual and sexual form of the same yeast, it was the most used source of astaxanthin before the advent of microalgae H. pluvialis. Its productivity is lower but several trials are underway upcycling to produce biomass through the use of low-cost nutrients, such as food waste, (3)
- Paracoccus carotinifaciens. This bacterium does not produce pure astaxanthin, but a mix of carotenoids of which it represents the primary component. Through classical mutagenic selection techniques (e.g. UV, chemical treatment), more productive strains have been selected, together with more suitable cultivation parameters.
4) novel foods based on astaxanthin
The use of astaxanthin in food in the EU it is currently authorized only in food supplements, with a warning of unsuitability for consumption for children and young people under the age of 14 (see par. 6). The first authorization a novel food concerns the astaxanthin-rich oleoresin from H. pluvialis', and a proposal to amend its terms of use is now under consideration. An additional NF application has also been submitted for oleoresin and seaweed meal H. pluvialis. Another novel foods with (esters of) astaxanthin, already authorized, is the oil of Calanus finmarchicus (small copepod crustacean).
5) Antioxidant action and other health benefits
The benefits of astaxanthin are multiple, thanks to the exponentially superior antioxidant bioactivity compared to other molecules (Mularczyk et al., 2020). (4) Since it is a fat-soluble compound, its bioavailability increases when taken with oils or fats. Several clinical studies have demonstrated astaxanthin's ability to reduce inflammation and strengthen the immune system, in addition to antimicrobial and antiviral activities. Other benefits reported in the literature (Ambati et al., 2014) with different levels of scientific evidence, concern:
- reduction of cholesterol and triglycerides in the blood,
- prevention of cardiovascular diseases,
- reduction of DNA damage and lower incidence of tumors,
- recovery from mental fatigue,
- skin protection from UV rays,
- maintenance of antioxidant function after oxidative stress from physical activity. (5)
Other clinical studies (Hayashi et al., 2021) have shown the ability of astaxanthin to prevent anxiety, gastric ulcer and retinal damage, as well as improve cognitive function. Assuming that these effects derive not only from astaxanthin but also from other AERs (astaxanthin-rich carotenoids) such as adonirubin and adonixanthin. (6)
6) Levels of exposure, ADI
EFSA (2020) reassessed the safety of astaxanthin in humans, based on exposure from novel foods authorized (max 8 mg/day of astaxanthin) and from the consumption of fish and crustaceans that contain it due to its use as a feed additive. The results, for target populations, were as follows:
- adults (70 kg body weight): exposure at 0,174 mg/day per kg body weight is safe, being 13% below the level of ADI (Acceptable Daily Intake) set in the opinions on feed additives at 0,2 mg astaxanthin per kg body weight,
- adolescents between 14 and 17 years (body weight 61,3 kg). Exposure is 0,2 mg/day per kg body weight, equivalent to the ADI,
- adolescents between 10 and 13 years (body weight 43,3 kg). The ADI is exceeded by 0,056 mg/day per kg of body weight (28% of the total ADI),
- children under 10 years old. Exposure varies between 0,25 and 1 mg/day per kg of body weight (ADI exceeded by 123-524%).
6) Astaxanthin in aquaculture
Aquaculture it is a sector where astaxanthin is widely used thanks to its ability to give the typical 'salmon' color to farmed fish species, such as salmon trout and salmon themselves, crustaceans, as well as ornamental fish. Nutritional supplementation with astaxanthin has revealed further health benefits PERFORMANCE production of aquaculture animals. It is in fact able to promote growth and weight gain.
The administration of astaxanthin together with the algal biomass also allows to:
- provide essential amino acids, mono- and polyunsaturated fatty acids, polysaccharides and vitamins, which enhance the effect of carotenoid,
- promote the functionality of the immune system, thanks to the antioxidant power, and thus reduce the need for the use of antibiotics in aquaculture,
- reduce lipid peroxidation, increasing the stability of the food and its nutritional properties (Lu et al., 2021. See notes 8,9).
7) Astaxanthin in poultry farming
The aviculture it is another sector of animal husbandry where astaxanthin is detecting great potential both for its antioxidant action and for the positive effects on the immune system and animal health. With a view to reducing and perhaps even eliminating the use of antibiotics and other veterinary drugs, as already tested in Italy with Algatan. (10)
Recent studies experiments on the use of astaxanthin in poultry farming (Zhu et al., 2021; Pertiwi et al., 2022) have in fact demonstrated the usefulness of its contribution both to promote the growth of meat poultry (broilers), and for the health and well-being of laying hens, with a favorable impact also on egg quality (11,12).
8) Uses in pig farming
Antioxidants not only do they affect the health and condition of the pigs, as well as the quality of the meat. Yang et al. (2006) demonstrated a tenfold reduction in back fat content and an increase in muscle mass after 14 days of feeding 3 mg/kg of astaxanthin. (13)
The accumulation of natural astaxanthin in the muscle tissue of pigs, following its inclusion in the feed ration, has an antioxidant action estimated to be four times higher than that of vitamin E. With effects superior to the action of the same molecule added to meat, to maintain its quality and conservation.
8) Provisional conclusions
The domain of microalgae continues to express potential that is still unexpressed or in any case underestimated. With a view to the production of nutraceutical ingredients, medicines and natural cosmetics, including through upcycling of CO2 and waste from other supply chains, as we have seen (14,15).
Global production of algae and microalgae - as stated in the report of the European Parliament (2023) which follows the 'EU algae initiative' (2022) – increased from 0,56 to 35,82 million tons between 1950 and 2019 (16,17,18). And Asia is the absolute protagonist, with 97%.
Research and innovation are essential to develop and validate effective processes and innovative products, to stimulate the birth of the blue bioeconomy. As the research project shows, for example ProFuture, in the program Horizonin Horizon4Proteins (19)
Dario Dongo and Andrea Adelmo Della Penna
Footnotes
(1) Villaro et al. (2021) Microalgae Derived Astaxanthin: Research and Consumer Trends and Industrial Use as Food. Foods 10: 2303, https://doi.org/10.3390/foods10102303
(2) Chen et al. (2017) Enhanced production of astaxanthin by Chromochloris zofingiensis in a microplate-based culture system under high light irradiation. Bioresource Technology 245: 518-529, https://doi.org/10.1016/j.biortech.2017.08.102
(3) Gervasi et al. (2019) Astaxanthin production by Xanthophyllomyces dendrorhous growing on a low cost substrate. Agrofor. Syst. 94:1229–1234, https://doi.org/10.1007/s10457-018-00344-6
(4) Mularczyk M, Michalak I, Marycz K. (2020). Astaxanthin and other Nutrients from Haematococcus pluvialis-Multifunctional Applications. Mar Drugs. 2020 Sep 7;18(9):459. doi: 10.3390/md18090459
(5) RR Ambati et al. (2014) Astaxanthin: Sources, Extraction, Stability, Biological Activities and Its Commercial Applications – A Review. Mar. Drugs 12: 128-152, https://doi.org/10.3390/md12010128
(6) Hayashi et al. (2021) Commercial Production of Astaxanthin with Paracoccus carotinifaciens. In: Carotenoids: Biosynthetic and Biofunctional Approaches. Advances in Experimental Medicine and Biology 1261:11–20, https://doi.org/10.1007/978-981-15-7360-6_2
(7) EFSA (European Food Safety Authority) NDA Panel (2020) Safety of astaxanthin for its use as a novel food in food supplements. EFSA Journal 18 (2): 5993, https://doi.org/10.2903/j.efsa.2020.5993
(8) Mon et al. (2021) Astaxanthin as a microalgal metabolite for aquaculture: A review on the synthetic mechanisms, production techniques, and practical application. Algal Research 54: 102178. https://doi.org/10.1016/j.algal.2020.102178
(9) For its use in aquaculture, astaxanthin should be authorized as a feed additive (category 'sensory additives', group 'colourants'). There are currently three authorized additives in the EU register (astaxanthin, astaxanthin-dimethylsuccinate, biomass of Phaffia rhodozyma rich in astaxanthin), with the relative permitted species. And a safety evaluation of is underway Paracoccus carotinifaciens, also to be used as a feed additive
(10) Dario Dongo, Andrea Adelmo Della Penna. Antibiotic-free poultry farming, the Italian way. GIFT (Great Italian Food Trade). 14.12.20
(11) Yuanzhao Zhu et al. (2021) Astaxanthin supplementation enriches productive performance, physiological and immunological responses in laying hens. Animal biosci. 2021 Mar; 34(3): 443–448. doi: 10.5713/ab.20.0550
(12) Herinda Pertiwi et al. (2022) Astaxanthin as a Potential Antioxidant to Improve Health and Production Performance of Broiler Chicken Vet. Med. Int. 2022; 2022: 4919442. doi: 10.1155/2022/4919442
(13) Yang, YX; Kim, YJ; Jin, Z.; Lohakare, JD; Kim, CH; Ohh, SH; Lee, SH; Choi, JY; Chae, B. J. (2006). Effects of dietary supplementation of astaxanthin on production performance, egg quality in layers and meat quality in finishing pigs. AJAS 2006, 19, 1019–1025. doi: 10.5713/ajas.2006.1019
(14) Dario Dongo, Andrea Adelmo Della Penna. Algae and microalgae for food use in Europe, the ABC. GIFT (Great Italian Food Trade). 14.11.22
(15) Dario Dongo, Giulia Pietrollini. Algae and microalgae. carbon farming e upcycling of CO2. GIFT (Great Italian Food Trade). 18.1.23
(16) European Parliament (2023) The future of the EU algae sector. https://bit.ly/733-114 Research for the PECH Committee doi: 10.2861 / 922543
(17) Martha Strinati. The European Commission proposes 23 actions for the seaweed industry. GIFT (Great Italian Food Trade). 23.11.22
(18) European Commission's Communication 'Towards a Strong and Sustainable EU Algae Sector (COM/2022/592 final)'https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A52022DC0592&qid=1685431066833
(19) Dario Dongo. ProFuture, microalgae to feed the planet. The EU research project. GIFT (Great Italian Food Trade). 18.6.19
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
Graduated in Food Technologies and Biotechnologies, qualified food technologist, he follows the research and development area. With particular regard to European research projects (in Horizon 2020, PRIMA) where the FARE division of WIISE Srl, a benefit company, participates.
