Astaxanthin (3,3?-dihydroxy-?,??-carotene-4,4?-dione) is a xanthophyll carotenoid contains hydroxyl and keto endings on each ionone ring. Astaxanthin found in many different organisms in nature such as bacteria, yeast, algae, shrimps, krill, and some fishes. Its chemical structure explains, the ability to be esterified, much higher anti-oxidant activity and a more polar configuration than other well-known carotenoids. It’s a fat soluble pigment present in its free as well as in its mono or di esterified form, depending on the respective organism and the storage site (e.g., flesh, skin, etc) (1). Astaxanthin is widely used in aquaculture nutrition as a coloring agent as well as a nutraceutical. Astaxanthin is, generally recognized as safe (GRAS) by the United States Food and Drug Administration (USFDA), and has approved the use of astaxanthin as food colorant in fish and animal feed (2). While the European Commission recognized natural astaxanthin as a food dye (3). Astaxanthin has significant applications in the nutraceutical, cosmetic and pharmaceutical industry due to its greater antioxidant activity.
Global shellfishery waste generation is from 6 to 8 million metric tons annually. Increased shrimp production has led to a higher amount of processing waste, which poses novel environmental problems. (Thiago et al.,) Commercial forms of shrimp that generate waste are headless, peeled and tail-on. The product is vary with the species and consumer. In this headless shrimp generating just the head, peeled shrimp is the product that generate maximum waste which includes head and full shell, and in Tail-on generate head and shell of shrimp without tail fin. The cephalothorax contains 35–45% of raw material and the exoskeleton consists of 47%. Together they represent up to 70% (w/w) of the raw material B.K. Simpson, N.F. Haard. This waste is composed primarily of cephalothorax, exoskeleton, viscera and muscle remnants, and contributes to increase pollution when improperly disposed A.O. Famino, O.O. Oduguwa, A.O. Onifade, T.O. Olotunde. Recovery of valuable components from industrial waste is very much important, to solve the problem with waste as well as profit generation. And of course shrimp shell waste is a cheapest source of astaxanthin.
Conventional procedures for the extraction of astaxanthin include maceration (6,7,8) soxlet (6)ultra sound(6,9,10) and oil extraction (6,8,11)techniques. Extraction method includes using organic solvents (Sachindra et al., 2006) using vegetable oils (Sachindra and Mahendrakar, 2005) enzymatic process (Gildberg and Stenberg, 2001; Chakrabarti, 2002; Armenta-Lopez et al., 2002; Holanda and Netto, 2006) fermentation process (Sachindra et al., 2007). As an alternative to the conventional extraction of carotenoid components which has limitations such as – high energy costs; elevated solvent use and time consuming; high temperatures, affecting the thermo labile substances; low selectivity; and retention of solvent traces in the solute 12, 13 Supercritical fluid extraction method introduced. Supercritical fluid extraction technology uses carbon dioxide (CO2) 14) for the extraction of astaxanthin from shrimp shell waste. In supercritical fluid extraction method is a superior technology for extraction of lipid and lipid associated compounds. Advantages of this new age technology over the conventional techniques includes (1) use of low temperatures and reduced energy consumption (2) efficiency in solvent use with recycling possibility (3) prevention of oxidation reactions and high product quality due to the absence of solvent in solute phase (4) it is a flexible process due to possibility of continuous adjustment of the solubility and selectivity power of the solvent through the selection of processing parameters 15,16. The aim of this work was the comparison of carotenoid recovered from shrimp waste of the food industry by supercritical solvent extraction method as a green technique with traditional solvent extraction in terms of yield and anti- oxidant potential.