## 1 Introduction  
It is now known that microalgae are able to improve the nutritional quality of foods and contribute to the improvement of human health thanks to their high content of macro and micronutrients. Among other things, they are a rich source of compounds capable of exerting biological activities. Spirulina is marketed as a \"health food\" in Japan, Taiwan and Mexico but has only recently gained ground in the food sector due to its peculiar flavor and aroma. _Arthrospira platensis_, belonging to the Oscillatoraceae family, is a multicellular blue-green microalga that thries in warm, alkaline, freshwater bodies. This cyanobacterium is among the edible spirulina species characterized by a high nutritional value; in fact, it contains proteins [1], polysaccharides, total lipids and nucleic acids [2]. A series of micronutrients such as vitamins [3], minerals and essential fatty acids make it suitable for a balanced diet [4]. Its use has been authorized by the FDA as a food or dietary supplement. In general, the addition of spirulina to foods and drinks can be seen as an option to improve sustenance and mass nutrition. Recently spirulina was incorporated into pasta with consequent nutritional fortification without altering the sensorial aspect [5; 6; 7]. After the addition of spirulina, an improvement in functional properties was also found in biscuits, smoothies and snacks [8; 9; 10]. In our previous work, the effects of adding spirulina to craft beer were evaluated. The results demonstrated that spirulina, in addition to modifying the content of compound esters, improved the cytoprotective properties of beer towards tBOOH-induced oxidative damage in H69 cells and reduced intracellular oxidative stress [11].  
The advantage in using spirulina in the food field is also due to the fact that by requiring an alkaline pH to grow, this does not favor the growth and development of other microorganisms with toxic effects [12]. In general, in recent times, the use of supplements such as spirulina in the form of pills or capsules is preferred to be taken following addition to commercial foods and/or drinks because the consequent color change leads to greater attraction and curiosity on the part of the consumer.  
Previous studies have also demonstrated a biological action of spirulina. For example, ethanolic and methanolic extracts have been shown to be effective as antifungals, and both cytotoxic and antioxidant [13; 14]. Synthetic antioxidants are generally dangerous for humans if used long-term, so a natural antioxidant source that can reduce or prevent cellular damage caused by oxidative stress may be crucial for the prevention of diseases such as cancer [15]. Ability to lower cholesterol levels and modulating properties of the immune system have also been reported [16].  
In light of the growing interest in this cyanobacterium and its potential uses, the aim of the present study was to further explore the chemical composition of _Arthospira platensis_. For this purpose, in our investigation, more analytical techniques such as GC/MS, SPME-GC/MS and PTR-ToF-MS were used to provide a more detailed description of the compositional profile of _Arthospira platensis_ grown in Italy, never investigated until now. Furthermore, the assessment of its antioxidant power, antimicrobial activity, and effectiveness as a prebiotic agent was performed to better know its beneficial effects.