# Rapid Green Extractions of C-Phycocyanin from _Arthrospira maxima_ for Functional Applications
## 1 Introduction  
In the present, many reports have focused on the prospect of potential functional ingredients due to an increase of interest in a healthy lifestyle [1; 2; 3]. The functional ingredients are bioactive compound(s) isolated or purified from natural sources with health-promoting properties demonstrating their relevant role in disease risk reduction [34]. Phycobiliproteins (PBP) are a group of coloured proteins mainly present in cyanobacteria (blue-green algae) and red algae. They are components of photosynthetic light-harvesting antenna complexes and they have a broad spectrum of functions [5; 6; 7]. In general, these proteins are classified into two large groups based on their colours and absorption spectra such as phycoverthrin (PE, red \(-\lambda\)max = 490-570 nm) and phycocyanin (PC, blue \(-\lambda\)max = 610-625 nm). In particular, the phycocyanins are included: C-phycocyanin (C-PC), R-phycocyanin (R-PC) and allophycocyanin (APC) which differ in their spectral properties, structural composition, and colour [8; 9; 10]. Nowadays, PBP has a broad market in pharmaceutical, biomedical, food and cosmetic industries due to their varied beneficial properties [5; 11]. The main use of PBP described is as non-toxic and non-carcinogenic natural food colorants [11; 12] and they exhibit a consolidated market in the clinical and immunological area due to their fluorescent capacity [13]. PC has also shown anti-inflammatory, antiplatelet, anti-cancer, nephprotective, and hepatoprotective properties justified by its antioxidant activity [14; 15]. Moreover, the current market of PBP is assessed to be more than 60 million USD [16] highlighting the role of C-PC as a fluorescent agent where its commercial value depends on its degree of purity (food-grade or analytical grade) [17]. The most named cyanobacteria for producing C-PC as natural blue pigment is _Arthospira_, also known as Spirulina, a blue-green alga [13]. Specifically, _Arthospira plantesis_ and _Arthospira maxima_ are the species mostly used with a wide market such as food additives, health food, cosmetics, pharmaceuticals and medicine [18; 19; 20; 21]. For those reasons, _Arthospira_ sp. is a promising source of C-PC that represents an opportunity for economic profit. Many reports have focused on improving the culture conditions from physical and chemical to engineer's parameters of the process, e.g., optimization of culture media, selection of stress conditions, bioreactor design etc. for increasing the bioactive compound synthesis in microalgae and cyanobacteria [22; 23]. However, the extraction methods are also a very important factor for the maximum recovery of PBP (functional ingredients). In the case of conventional methods such as maceration extraction (M, soaking in solvent), freezing and thawing are the most used for PBP extraction; however, the process can be quite lengthy [12; 24]. Normally, these types of extraction methods start from dry biomass and then a thermal extraction with organic or aqueous solvents is used, depending on the polarity of the target compounds to be extracted [25]. The main problems presented in the conventional extraction process are moderate extraction efficiency and selectivity and high solvent consumption [25]. On the other hand, there are green extraction techniques that are defined because they do not use solvents or chemicals harmful to the environment and it is also reported that they show better results for the extraction process. They could be classified in general as: pressurised liquid extraction (PLE), supercritical fluid extraction (SFE), microwave extraction (MW), ultrasound (US) and high-pressure homogenization (HPH) between other technologies [25]. Additionally, the PBP are also soluble-water compounds, and for this reason the selection of suitable solvent as buffer is also a very crucial factor for obtaining high-yield and -quality PBP [26].