## 1 Introduction  
Bread, a dietary staple consumed worldwide, serves as a vital source of essential nutrients. In recent years, people have become more aware of products that include functional ingredients. Wheat bread has garnered attention among researchers as a medium for delivering essential nutrients and bioactive compounds [1]. Incorporating microalgae into bread can enhance its nutritional profile and provide diverse bioactive constituents [2, 3]. Microalgae are known as a sustainable and excellent source of numerous phytochemicals that feature remarkable functional activities and health impacts, including improving gut health, boosting immunity, and reducing the risk of chronic diseases such as cancer, diabetes, and cardiovascular disease [4, 5]. According to a report by Market, the global microalgae market size is projected to grow from USD 3.4 billion in 2020 to USD 4.6 billion by 2027 at a compound annual growth rate (CAGR) of 4.3% [6]. In previous studies, microalgae have been incorporated into various food products such as cheese, vegetable soups, pasta, and snacks like cookies and energy bars, consistently demonstrating substantial improvements in nutrient content, bioactive compounds, and antioxidant capacity [7; 8]. There has been limited research conducted regarding the inclusion of microalgae in bread products, although the limited findings indicate that their inclusion results in an improvement in the nutritional balance and antioxidant capacity of bread. These studies primarily focused on the most popular and cultivated strains of microalgae and cyanobacteria approved by the European Food Safety Authority (EFSA): _Arthospira platensis_ (Spirulina) sp. and _Chorella_ sp. as ingredients [9; 10; 11]. _Chorella vulgaris_ is a freshwater green microalgae and represents a valuable source of nutrients, including high-quality proteins like those found in eggs and soybeans (its amino acid profile is even more complete than that proposed by FAO/WHO as a standard for human nutrition), polysaccharides (starch and glucans), pigments like carotenoids and chlorophylls, and vitamins [9; 12] (which vary according to the growing conditions). If grown under favourable conditions, the resulting lipid profile is more concentrated in polyunsaturated fatty acids (PUFAs), being more suitable for nutritional uses [13]. _C. vulgaris_ has already demonstrated immunomodulatory and anticancer properties and displayed protective activities against cardiovascular disease, hypertension, and cataracts [14; 15]. It also has the potential to inhibit the growth of pathogenic microorganisms in food, namely in bread [16]. Due to its historical use, _C. vulgaris_ is considered a food ingredient and is well established in the market, being exempt from approval by the EFSA as a novel ingredient. It has also already been generally accepted as safe (GRAS) by the Food and Drug Administration (FDA) in the United States of America. _C. vulgaris_ is one of the most studied and cultivated microalgae due to its regulatory status. _Tetraelmis chuii_, a marine phytoplankton belonging to the _Prasinollycease_ class, is distinguished for its abundant bioactive compounds and antioxidant enzymes. All essential amino acids are present, making _T. chuii_ a complete protein source. Also recognised for its richness in PUFAs, this species contains \(\omega\)-3 fatty acids, such as docoshexaic acid (DHA) and eicosapentaenoic acid (EPA). It shows promise in reducing oxidative stress, aiding exercise recovery, and enhancing immune function, as indicated by studies conducted by [PERSON] et al. [17], [PERSON] et al. [18], and [PERSON] et al. [19]. Notably, _T. chuii_ received approval for use under Regulation (EU) 2017/2470, being limited to sauces, salts, and conditions, with a maximum incorporation level of 250 mg/serving/d. _Phaeodactylum tricornutum_, a marine diatom species, has been extensively investigated, with its genome fully sequenced, since the late 2000s.