Microalgae as novel ingredients for the formulation of food products

Abstract

Microalgae are microscopic unicellular and photosynthetic organisms that can be found in a wide variety of environments. These microorganisms are very efficient when transforming solar energy into biomass, due to their cellular structure, which is completely submerged in an aqueous medium, forming an adequate surface for the exchange of nutrients and gases. Microalgae compounds are now known to exhibit cardioprotective, immunomodulatory, anti-proliferative, anti-inflammatory, cognitive, neurobehavioral and antimicrobial properties, amongst others. Researchers have shown possible benefits of the incorporation of microalgae in the diet so far. The most common way to consume microalgae is as a dietary supplement in the form of tablets, capsules or powder. The incorporation of microalgae biomass in traditional products has faced the challenge of the appearance of strong green colours, as well as its powdery consistency that can affect the texture and perception of the product. All these aspects constitute the main areas for improvement the development of microalgae-based products, and they are the challenges faced of this project. The main objective of this PhD Thesis was the development of novel food products incorporating the nutritional properties of microalgae biomass, thereby increasing or improving the nutritional properties of the original food matrix. To achieve this goal, the effect of the addition of different species of microalgae (Arthrospira platensis (Spirulina), Chlorella vulgaris, Dunaliella salina and Nannochloropsis gaditana) on the physicochemical, rheological and textural properties of different food matrices (baked products, emulsions and extrudates) was evaluated. Furthermore, the effect of the incorporation of microalgae using different technologies such as 3D printing or extrusion to obtain food products was studied. In addition, how the incorporation of microalgae affects the nutritional aspects of the food products in terms of the contribution of minerals and their bioavailability was also evaluated. The rheological properties of doughs, batters and emulsions enriched with microalgae (Spirulina, Chlorella and Dunaliella) indicated that their viscoelastic behaviour was modified and improved, showing characteristics suitable for this type of products. The addition of microalgae (Spirulina and Chlorella) to the doughs and batters used for the 3D printing of cookies and snacks, allowed a better extrusion or printing behaviour. This allowed obtaining cylindrical 3D printed samples, more precise in terms of their dimensions with respect to the designed cylindrical structure. In addition, the 3D microalgae-printed sample structures presented greater stability and resistance, before and after the baking process compared to the control sample. For baked products, both for breadsticks and 3D printed snacks, the addition of microalgae (Spirulina and Chlorella) allowed greater stability in terms of texture. Slight changes in the physicochemical and expansion parameters were produced by the addition of Spirulina and Chlorella in the extruded products. In addition, the extrudates enriched with Nannochloropsis, showed similar parameters to those of the control sample. Microalgae-enriched obtained products showed bright colours with appealing appearances. Regarding minerals, an increase in P, K, Ca, Na, Mg, Fe and Se was observed with the addition of Spirulina and Chlorella, along the increase of concentration of microalgae addition. Following the regulations on nutrition labelling for food stuffs, breadstick enrichment with microalgae are a food high in iron (Fe) In the same way, breadsticks and cookies enriched with microalgae can be considered a high in selenium (Se) food. Going a step further, Spirulina and Chlorella vulgaris incorporation in cookie formulations allowed for greater bioaccessibility of P, K, Ca, Mg, Fe, Zn, and Se content for absorption in the body than control cookies.