## 1 Introduction  
In addition to taste, aroma, and texture, the color of food is a main factor that influences its total acceptability. Therefore, since ancient times, people have used multiple colorants in their food to improve its appearance, flavor, taste, preservability, and nutrient quality. Food colorants can be obtained either from natural sources (plants, animals, or microorganisms) or through chemical synthesis [1, 2]. Owing to the differences in the origin and composition of the applied food colorants, the degree of health risk and environmental suitability varies widely [3, 4]. Chemically synthesized food colorants are not preferred because of their potential toxicity, carcinogenicity, and undesirable side effects on human health and the environment. Natural food pigments are gaining increasing popularity globally, as they are safe to use and have several nutritional benefits and potential medicinal properties [4; 5; 6]. Microorganisms (bacteria, fungi, and microalgae) are among the most promising natural sources of food colorants, which can be produced both intracellular and extracellularly. They are characterized by high, sustainable productivity and relatively low costs, as they can be cultured on agricultural and food wastes at any time of the year. In addition, the pigments obtained are varied, easily extractable, and relatively heat-stable, offering several health and nutritional benefits [7; 8]. The fungus _Monascus_ was widely used in East Asian countries approximately two thousand years ago, and it continues to be used for the fermentation and coloring of foods, particularly rice (to produce red rice), which is also referred to as \"red yeast rice\", \"hongqu,\", \"red mold rice\", \"red koji\", and \"anka\" in traditional medicine. However, the name \"_Monascus_ spp.\" was proposed only in 1884 for a versatile group of filamentous fungi comprising _Monascus floridanus_, _Monascus pallens_, _Monascus pilosus_, _Monascus purpureus_, _Monascus ruber_, _Monascus sanguineus_, _Monascus remophilus_, _Monascus lunisporas_, and _Monascus argentinensis_[9; 10; 11]. Pigments produced by _Monascus_ by natural fermentation have a high economic value and have attracted considerable attention as coloring agents globally. They have several advantages, such as ease of production using inexpensive substrates, favorable solubility in acidic water and ethanol, presence of numerous bioactive metabolites, and safety when produced under specific conditions [12]. _Monascus_ spp. are able to synthesize different (intracellular and extracellular) polyktetide secondary metabolites that protect cells against oxidative stress (antioxidants) and produce different and distinct pigments. The most common pigments produced by _Monascus_ are orange (monascorubrin and rubropunctatin), yellow (monascin and ankaflavin), and hydrosoluble red (monascorubramine and rubropunctamine). The percentage of production of each pigment by _Monascus_ is highly dependent on the species and cultivation conditions (substrate, fermentation mode, dissolved oxygen, pH, and temperature). Of the several pigments produced by _Monascus_, the red pigment (monascorubramine) is in high demand [4; 13; 14; 15]. Solid-state fermentation of rice and grains is the traditional method for cultivating _Monascus_ to produce high levels of pigments, although it has been linked to scale-up- and contamination-related issues [16]. In addition, traditional solid-state fermentation processes are labor-intensive, time-consuming, and require large cultivation areas [17; 18]. _Monascus_ strains usually produce lower levels of pigment in submerged cultivation than in solid-state cultivation [19]. However, the production of pigments by _Monascus_ under submerged fermentation is characterized by controlled cultivation conditions and medium, which helps to control the production of secondary metabolites [10]. During the growth of certain _Monascus_ strains, the mycotoxin citrinin is produced as a secondary metabolite under specific fermentation conditions [20; 21].