## 1 Introduction  
Beer is a complex mixture of components, produced from a variety of raw materials such as water, yeast, malt and hops, and contains a large number of chemical compounds, but only a small number of these compounds are \"flavor-active\", i.e., directly involved in the production of flavor sensation when the product is consumed. The volatile fraction can be composed of countless compounds belonging to different chemical classes, including higher alcohols, esters, fatty acids, carbonyl compounds, sulfur compounds and furans [1]. The growing demand for a protein supply for human nutrition has led to the exploration of new and alternative protein sources such as unicellular proteins (SCPs). Manymicro-organisms (algae, bacteria, yeast/filamentous fungi) can be used as a source of SCP, but due to their low nucleic acid content and high level of essential amino acids, algae are preferred over fungi and bacteria as a source of SCPs for human consumption, so the world production of microalgal biomass is steadily increasing [2; 3]. The cyanobacterium _Arthospira platensis_ (known commercially as spirulina) is an edible, symbiotic, multicellular, filamentous blue-green microalgae that belongs to the cyanobacteria group (i.e., bacteria that fix nitrogen from the air) [4], and it is used as a food by Mexican and African people [5]. Currently, it is produced commercially in large open ponds under controlled conditions and is widely used as a safe functional food. The potential health benefits of spirulina are mainly due to its chemical composition, which includes proteins, carbohydrates, essential amino acids, minerals (especially iron), essential fatty acids and vitamins [6; 7]. Precisely thanks to its high protein content (it can vary from 50% to 70% [8]), spirulina is added to many foods such as isotonic drinks, cereal bars, instant soups, puddings, powdered preparations for cakes and biscuits and bread sticks [9]. Spirulina powder has been also used as an ingredient for chewable wafers to make chocolate bars and biscuits [10]. Most cyanobacteria, including spirulina, are capable of synthesizing vitamin B12 [11], also known as cobalamin, a water-soluble vitamin involved in the metabolism of every cellular function in the human body, and other vitamins such as vitamin K, vitamin A,tocopherol isomers (vitamin E) and metabolic intermediates [12]. Among microalgal pigments, phycobiliproteins (phycocyanin and phycerythrin) play an important role in the commercial and biotechnological fields, with wide applications as natural dyes, dietary supplements and antioxidants, and in the biomedical and pharmaceutical fields as well [13]. The phycocyanophilin spirulina can function as a NOX inhibitor. It is also a powerful free radical scavenger with the ability to scavenge hydroxyl, hydroxyl, peroxyl, hypochlorite and peroxynitrite radicals [14]. The use of spirulina protein concentrates has also been proposed as an alternative ingredient for the formulation of dietary supplements [15]. Additionally, in the cosmetic sector, a product based on a spirulina extract has been used for its skin properties, such as anti-aging, bringing benefits for the face and body [16]. It is also used as a pigment in lipsticks, eyeliners and eye shadows, and as an antioxidant and thickening agent in skin and hair care products and sunscreen [17]. In the United States, the FDA has classified spirulina extract as a certification-exempt color additive and approved its use in confectionery and other foods, while currently, in the European Union, spirulina extract is classified as a food colorant. Over the years, beer has attracted great attention for its nutritional value and for its particular taste; in line with the growing interest in foods and beverages capable of combining nutritional value and healing properties, improvements in the composition of beer, through the addition (e.g., microalgae, plant extracts, fungi, probiotics, etc.)