## 1 Introduction  
The green microalgae _Chlorella vulgaris_ and the cyanobacterium _Arthrospira platensis_ (Spirulina) have a long history of use and have been cultivated in Europe for many years as food and food additives [1]. Especially in recent years, there is an increasing interest in plant proteins and other alternatives to meat due to the ethical, health, and environmental concerns that go along with meat consumption [2; 3; 4]. Compared to terrestrial crops, microalgae have many advantages, such as high productivity; a high content of macro- and micro-nutrients; and low carbon, water, and arable land footprints [5]. However, food products containing either whole microalgae or compounds derived from microalgae are a minority on the food market as they are primarily sold as dietary supplements, e.g., capsules, tablets, or powder for ingestion [6]. According to [PERSON] [6], several challenges related to production capacities and costs, as well as legislation, must be overcome, but also the intense green color and a fishy taste and aroma represent one of the main problems in the integration of microalgae into food. The acceptance of products containing (micro)algae depends strongly on the traditional diet and is significantly higher in eastern countries [7; 8]. The addition of microalgae into recipes for traditional food products, such as bread, is a global trend [6]. However, not much is known about the effects of microalgae supplementation on food properties. [PERSON] et al. [9] reported that adding 2.5 or 5.0% Spirulina or differently colored _C. vulgaris_ strains (green, yellow, white) to energy bars not only changes the color, flavor, and texture of the products but can offer different colorways as well as different sensory profiles during product development. In the case of a fermented whey sport drink enriched with Spirulina (0.25-0.75%) and a fermented yogurt enriched with Spirulina (0,25-1.0%), only lower concentrations (0.5 and 0.25%, respectively) proved to contribute positively to stability and taste [10; 11]. Also, [PERSON] et al. [12] reported that the substitution of wheat flour dough with 1.0-5.0% green _C. vulgaris_ was only beneficial up to a concentration of 3.0%, while at higher concentrations, dough rheology, bread texture, flavor, and bread aging were negatively affected. Green microalgae incorporation into broccoli soup (0.5-2.0% _Spirulina_ sp., _Chlorella_ sp. or _Tetraselmis_ sp.) and into wheat torillas (0.5-3.0% _Nannochloropsis_ sp. or _Tetraselmis_ sp.) revealed changes in color and higher amounts of bio-accessible polyphenols in the microalgae-containing products [13; 14]. Although the sensorial acceptability index was reduced for soups containing microalgae compared to the control, it was still 80% for samples containing 0.5% Spirulina or _Tetraselmis_ sp. [13]. The green color and the fishy taste, therefore, seem to be less disturbing in green foods, which have a strong taste of their own. When adding the green microalgae _Nannochloropsis_ and _Tetraselmis_ to baked crackers and bread, substitution was limited to 2.5% for crackers and 1.0-2.0% for bread containing _Nannochloropsis_ and _Tetraselmis_, respectively. The sensory evaluation showed the products to be only competitive with the controls while having an improved nutritional value and including a \"trendy\" ingredient [15]. These findings are supported by recent consumer studies showing that young, physically active, well-educated Italian men who are interested in healthy eating and primarily have a plant-based diet are open to trying new products, such as pasta containing 3% Spirulina [16]. In addition to consumer openness, the label on the packaging, e.g., organic, Nutri-Score, or vegan, also plays a major role in whether consumers see added value in buying microalgae-enriched pasta and would pay more money for it [17]. Pasta is an interesting food to be substituted with algae, as consumers are familiar with different colors (yellow, red, green, black).