Extractive Components of the Squid Ink

Abstract

An extract was prepared with trichloroacetic acid from the inks of neon flying, boreal clubhook, and boreo pacific gonate squids and free amino acids, trimethylamine oxide, 5′-ATP and related compounds, betaines, and other extractive components were analyzed. The squid inks were rich in taurine and hydroxyproline. Higher amounts of aspartic acid, glutamic acid, alanine, leucine, and arginine were detected in the boreal clubhook and boreo pacific gonate squid inks. Each free amino acid of the neon flying squid ink was lower than those of the boreal clubhook and boreo pacific gonate squid inks. A small amount of trimethylamine oxide and large amounts of homarine and glycinebetaine were detected in three squid inks. Ethanol extract was prepared to determine the extraction capability. There were some composition similarities between ethanol and trichloroacetic acid extracts. Ethanol was inferior in extraction of inorganic ions, even in the case of the hot-ethanol extraction. The hot-water extract showed that amounts of glycine, α-aminobutyric acid, Cl-, and PO43- were higher than those of the trichloroacetic acid extract of the neon flying squid ink.