The use of natural sources of ingredients to develop functional foods with sustainable components has become a key focus in the food industry. Among these, marine resources - especially microalgae and seaweeds - stand out as promising options. Their high levels of proteins, fatty acids, minerals, fiber and other essential nutrients make algae increasingly popular in human diets around the world, offering noteworthy potential health benefits^1,2,3.

This study develops a more nutritious and convenient version of Caldo Verde soup by replacing cabbage with micro- and macroalgae. Three algae were tested: Chlorella vulgaris (spray-dried) and the seaweeds Ulva rigida and Alaria esculenta. They were added to the soup at different ratios. The base recipe used water, cauliflower, leek, onion, garlic powder, pepper, and olive oil. Formulations included 1% U. rigida (UrTw) or A. esculenta (AeTw); combinations of 0.5% seaweed with 1% or 2% C. vulgaris (UrTwCv1, UrTwCv2, AeTwCv1, AeTwCv2); and each seaweed with 0.5% C. vulgaris (UrwCv, AewCv). The soups were heated to 100 °C for 40 minutes and analyzed for physicochemical and nutritional parameters. Adding algae increased nutritional value - particularly proteins, lipids, minerals and phenolics. The 2% C. vulgaris formulations (UrTwCv2 and AeTwCv2) had the highest nutrient levels and qualified as sources of iron and/or manganese, while A. esculenta significantly boosted phenolic content. Overall, both microalgae and macroalgae improved nutritional quality; however, the control soup showed higher in vitro digestibility (~64%) than the algae-enriched versions (~45%), indicating easier breakdown during digestion.

A PCA showed that the first two components explained 93.34% of the variance, linking nutritional composition to consumer acceptance. Soups with macroalgae were more appreciated despite lower nutritional values, whereas microalgae-enriched samples were nutritionally superior but less liked. This highlights a trade-off: microalgae improve nutrition but may reduce consumer appeal.

KEYWORDS

Functional foods, microalgae, macroalgae, nutritional profile, soups, bioaccessibility

FUNDINGThis work was financially supported by:

i) Pacto da Bioeconomia Azul (Projeto C644915664-00000026), WP5 Algae Vertical, suportado pelo Next Generation EU e pelo Plano de Recuperação e Resiliência (PRR), no âmbito das Agendas para a Inovação Empresarial – esquema de financiamento C5 – Capitalização e Inovação Empresarial; ii) Fundação para a Ciência e Tecnologia (FCT), através do projeto UID/04129/2025 do LEAF – Linking Landscape, Environment, Agriculture and Food.

REFERENCES

1. 1. Matheus, J., Alegria, M. J., Nunes, M. C. & Raymundo, A. Algae-Boosted Chickpea Hummus: Improving Nutrition and Texture with Seaweeds and Microalgae. Foods 13, 2178 (2024).
2. 2. Nunes, M. C., Ferreira, J. & Raymundo, A. Volatile fingerprint impact on the sensory properties of microalgae and development of mitigation strategies. Current Opinion in Food Science 51, 101040 (2023).
3. 3. Mendes, M. et al. Algae as Food in Europe: An Overview of Species Diversity and Their Application. Foods 11, 1871 (2022).