Microalgae are a very promising functional ingredient, due in part to the richness and appreciable digestibility of protein and amino acids.
Their benefits for nutrition and finds confirmation in the latest study (Prandi et al., 2023) published as part of the #ProFuture research project in Horizon 2020. (1)
1) ProFuture, research on the use of microalgae in food and feed.
The ProFuture(Proteins for the Future) project has improved the state of research on microalgae-based foods and feeds. Through innovation on processes and new product development, as well as effective market strategies to foster their positive impact on public health and the environment. Scientific studies to date in this area include:
– Formulation of plant creams with ProFuture microalgae, to increase nutritional value, and study the market rise of microalgae products in the EU market, (2)
– Market research on alternative foods to meat, with a focus on Alt Yogurt and Alt Cheese, (3)
– Use of solar dryers (direct and hybrid), as an alternative to freeze-drying, for moisture removal in microalgae, (4)
– potential of a fifth microalga, Galdieria sulphuraria, in the production of the pigment C-phycocyanin, compared with the cyanobacterium Arthrospira platensis. (5)
All of the studies conducted so far in Profuture have had very positive outcomes, opening up new perspectives on the use of microalgae-made by innovative and sustainable processes-as functional ingredients to be included in various food products, from plant-based creams to vegan protein bars. Promising prospects that deserve further experimentation and research on other food categories.
2) Vegetable creams with and without microalgae, protein digestibility
The researchers, in the study under review, evaluated the in vitro digestibility of proteins in vegetable creams with and without the addition of the microalgae. In continuity with the previous study, where the nutritional, technological and organoleptic properties of plant creams with the addition of four different microalgae (i.e. Arthrospira platensis, Chlorella vulgaris, Tetraselmis chuii, Nannochloropsis oceanica) were evaluated at 1.5 and 3 percent concentrations. Samples were provided by the companies Necton and Allmicroalgae (Portugal).
The digestibility of protein in foods can be assessed by several methods:
– PDCAAS, DIAAS. A score measures the fecal or intestinal absorption of amino acids in protein, compared with that of a standard protein (e.g., casein). This method is often used to evaluate the digestibility of novel foods (e.g., atomized cricket powder),
– Simulation of gastrointestinal digestion. The INFOGEST 2.0 protocol, used in the present study, was developed in the last decade for the harmonization of in vitro digestion analysis methods and is now being adopted on several continents (6,7).
3) Characterization of proteins and amino acids.
The four microalgae were analyzed for their protein content, and for constituent amino acids, taking into consideration the presence of essential and nonessential amino acids. The results report that:
– Arthrospira platensis has the highest average protein content (57.50 g/ 100 g dry weight), while for the other species it approximates 35-45%, except for Chlorella vulgaris, which drops to 26.30%,
– amino acid content varies among species, with the exception of cysteine. The highest values in descending order are identified for A. platensis, N. oceanica, T. chui, C. vulgaris, for both essential and nonessential amino acids,
– A. platensis and C. vulgaris have negligible amount of non-protein nitrogen (NPN), which increases more significantly in T. chuii and N. oceanica.
Protein content was measured by the Kjeldahl method, which allows the total nitrogen in the food to be determined and a conversion factor to be used. However, the common conversion factor, N x 6.25, although also referred to in the Food Information Regulation EU No 1169/2011, (8) can lead to an overestimation of protein in some foods, such as microalgae. IRTA researchers have therefore adopted dedicated conversion factors for their different species. (9)
4) In vitro digestibility of proteins.
The average degree of protein hydrolysis (DH%) of microalgae powders-analyzed after digestion-is 42%, within a range of 29-57%. The results are slightly different from those of other studies, where DH% was higher for all species. The deviations can be explained as follows:
– variety of protocols used (digestion models, sampling, enzymes used),
– Use, in many studies, of fresh rather than dried microalgae,
– Differences between microalgae. At the level of species and strain, but also in terms of how the cell walls are grown and broken down according to the techniques used.
5) Effect of adding microalgae in herbal creams.
The total protein content in plant creams differs according to species and added concentration. Spirulina at 3% made the largest contribution of both protein and amino acids. Reformulated creams have been found to meet essential amino acid requirements only as of children > 3 years old, with lysine alone as the limiting amino acid. In fact, the number of limiting amino acids is too high to meet the needs of early childhood.
The protein digestibility of the vegetable creams obtained with the addition of the four microalgae is appreciated, with a DH% value ranging in the 38-53% range. No significant difference was observed in DH% of the different formulations with respect to microalgae concentration and species. Therefore, the high protein digestibility of the standard vegetable cream (without microalgae) was not altered by the addition of any of the four microalgae species, which are precisely endowed with good protein digestibility.
6) Interim Conclusions
The addition of microalgae to plant creams makes it possible to:
– to maintain a stable protein concentration, in some cases to increase it significantly, without altering digestibility. Most importantly,
– significantly increase the concentration of amino acids to improve their nutritional value.
Protein should, moreover, be determined, on these and other foods, using more appropriate conversion factors-applying the Kjeldahl method-in order to have a more truthful estimate of the true protein value. The conversion factor N x 6.25, although established as a general criterion in the Food Information Regulation, may in fact lead to ex lege misinformation of consumers. Of particular note on novel foods, where general knowledge does not rest on established literature.
Dario Dongo and Andrea Adelmo Della Penna
This article is dedicated to Prof. Stefano Sforza of the University of Parma, co-author of the protein digestibility study, who passed away in July 2023, shortly after its publication. (10)
Notes
(1) Barbara Prandi, Fatma Boukid, Simon Van De Walle, Sara Cutroneo, Josep Comaposada, Geert Van Royen, Stefano Sforza, Tullia Tedeschi, Massimo Castellari (2023). Protein Quality and Protein Digestibility of Vegetable Creams Reformulated with Microalgae Inclusion. Foods 12:2395, https://doi.org/10.3390/foods12122395
(2) Dario Dongo, Andrea Adelmo Della Penna. Adding microalgae to vegetable creams, ProFuture. GIFT(Great Italian Food Trade). 3.11.21
(3) Dario Dongo, Andrea Adelmo Della Penna. Alt Yogurt and Alt Cheese, market and criticality. ProFuture research. GIFT(Great Italian Food Trade). 28.12.21
(4) Dario Dongo, Andrea Adelmo Della Penna. ProFuture, solar drying for sustainable microalgae. GIFT(Great Italian Food Trade). 13.8.22
(5) Dario Dongo, Andrea Adelmo Della Penna. Galderia sulphuraria, the blue pigment microalga. GIFT(Great Italian Food Trade). 27.12.22
(6) Brodkorb et al. (2019). INFOGEST static in vitro simulation of gastrointestinal food digestion. Nature 14:991-1014. doi: https://doi.org/10.1038/s41596-018-0119-1
(7) INFOGEST is a COST(European Cooperation in Science and Technology) action, funded by the Horizon program in 2011-2015, which later became an international research network to improve the health properties of foods by sharing knowledge about the digestive process. Altogether, INFOGEST brings together more than 440 scientists from 150 institutes in 45 Laeses in Europe as well as the U.S., Canada, Argentina, Australia, New Zealand, etc. And cooperates with food authorities such as EFSA
(8) Food Information Regulation (EU) No 1169/11. Annex I, paragraph 10
(9) Wang et al. (2021). Microalgae as Sources of High-Quality Protein for Human Food and Protein Supplements. Foods 10:3002. doi: https://doi.org/10.3390/foods10123002
(10) University of Parma. University condolences on the passing of Prof. Stefano Sforza https://www.unipr.it/notizie/cordoglio-dellateneo-la-scomparsa-del-prof-stefano-sforza
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.
