Instrumental Analysis of Seafood Flavour

Abstract

The complex flavour of seafood is composed of equally important nonvolatile taste-and aroma-active components. Early investigations on seafood flavour focused mainly on the taste-active components, which are generally non-volatile and low-molecular-weight extractive components. These may be divided into two broad groups: nitrogenous compounds including amino acids, low-molecular-weight peptides, nucleotides, and organic bases; and non-nitrogenous compounds including organic acids, sugars, and inorganic constituents such as mineral salts [1,2]. Study of the taste active constituents has attracted considerable attention and their importance to seafood flavour has been thoroughly reviewed [3][4][5][6]. The first study of this type was conducted during the early 1900s [7]. Since that time, most investigations in this area have involved the quantitative analysis of extractive components (mainly nucleotides and free amino acids) by wet-chemical and/or liquid chromatographic methods, including ion exchange chromatography and high-performance liquid chromatography [6,[8][9][10][11][12][13][14].Volatile (aroma) constituents are key to flavour perception. Without aromas, it is very difficult to identify the flavour of specific food products including seafood [15]. Seafood aromas can be formed via several mechanisms, which may be subdivided into four categories according to a precursor-mechanism relationship: 1) enzyme-mediated conversion of lipids to aromas; 2) autoxidative degradation of free fatty acids leading to the formation of volatile carbonyls, acids, and alcohols; 3) enzymatic conversion of sulphur-and nitrogen-containing precursors to volatiles including dimethyl sulphide; and 4) thermal decomposition of precursors upon processing or cooking [16].The aroma components may contribute to the development of pleasant (characteristic flavour) or off-flavour characteristics of seafood. The characteristic flavour of seafood has been described as green, melon-like, and iodine-like, while off-flavours include musty, fishy, woody, rancid, and petroleum notes [4,17]. Research on the volatile constituents of seafood Handbook of Seafood Q uality, Safety and Health ApplicationsEdited by Cesarettin Alasalvar, Fereidoon Shahidi, Kazuo Miyashita and Udaya Wanasundara