## 1 Introduction  
For thousands of years, people have relied on algae as a traditional food source, notably in Asia, because of its widespread availability, accessibility, diversity, and nutritional content. However, worldwide interest has recently increased as a result of the fact that algae are a valuable source of structurally different bioactive compounds (such as polysaccharides, phenolics, volatile organic compounds, and natural pigments) with different health benefits. In addition to being inexpensive and naturally rich in nutrients, there are still some issues related to the bioaccessibility, bioavailability, and stability of bioactive compounds [1, 2]. Natural pigments have attracted a lot of attention in the past few years due to their potential for use in medicine and pharmaceuticals [3, 4], as well as the fact that they can be utilized as alternatives to synthetic dyes and colors [5, 6]. Algae include three primary types of pigments: carotenoids, phycobilproteins, and chlorophylls [7]. The main issue with using natural pigments, such as carotenoids, as colorants in commercial applications is that they have a limited tolerance for temperature changes, heating, and light exposure. Their decomposition can also be accelerated by oxygen and other oxidizing substances. Microencapsulation is a technique that can be used to protect chemicals of natural origin. Microencapsulation techniques that are most frequently utilized are spray techniques (spray cooling, spray drying, spray drying with CO\({}_{2}\) at a supercritical state), freeze drying, extrusion, and coacervation [8]. CO\({}_{2}\) in a supercritical state is an important tool for the creation of new active compound delivery systems through particle formation. Supercritical fluids are an alternative technology for encapsulating active compounds where the bioactive compounds are entrapped into a matrix as a carrier material to increase the product shelf life, while also managing the active compound's dissolution rate. As an alternative to conventional microencapsulation techniques such as solvent displacement and self-emulsifying systems, this technique completely avoids organic solvents and post-treatment processes that are time and energy-consuming and with remaining residual solvent levels which represent a safety risk [9; 10]. The possibility of producing novel delivery systems, technically and economically feasible, without any additional steps typically required by traditional techniques, such as the drying of microparticles, has enormous importance within pharmaceutical and food industries [10; 11]. By reducing particle size and increasing surface area, bioavailability (the difference between the initial dosage and the medicine absorbed in a target area in the human body) can be improved, resulting in increased dissolution. Small pharmaceutical particles with a reduced particle size distribution play an important role in the design of traditional active compounds delivery systems including tablets, syrups, capsules, and injections [12; 13; 14]. During the micronization process, the mixture containing core material (bioactive compound and shell material) is saturated with CO\({}_{2}\) and then the CO\({}_{2}\)-containing solution is rapidly expanded in an expansion section. Due to the Joule-Thomson effect (evaporation and volume expansion of the gas), the solution cools below the solidification temperature of the solute. This results in the formation of particles. Microparticles can be easily separated from the CO\({}_{2}\) stream in a spray tower (gas-liquid contactor) [14]. Encapsulation of natural compounds, lipids and fat derivatives, medicines, synthetic and natural compounds with antioxidant activity, surface-active chemicals, and UV stabilizers are among the most common applications of this technique [15]. This study aimed to determine the possibilities in the encapsulation of pigments using particles from the gas-saturated solutions (PGSS) process to improve its stability and bioaccessibility effectively.