Taste shellfish

Man is capable of living on an all plant or all animal diet, although omnivory is most common in human societies. Animal foods may be divided into two major categories as far as we are concerned vertebrate and invertebrate. Although invertebrate animals may play a significant part in the diet of many human societies, there has been little work on invertebrate taste chemistry (except for shellfish) from a human consumption standpoint. Shellfish taste is primarily due to inorganic ions, organic acids, amino acids and nucleotides (44). 

Water-binding agents. Preparations of protein hydrolysates containing amino acids and peptides obtained from marine raw material, particularly fish fractions, presently represent a very interesting area of research. As with the above-mentioned extracts, these preparations may find use in foods, particularly seafoods, because of their typical fish or shellfish taste. In addition, the peptides may have special effects when added to frozen fish, retaining some of the muscle juiciness and perhaps also yielding a better taste characteristic of the frozen fish. 

Coupled with successful primary prevention are ongoing monitoring programs for the organisms and their toxins, both in the environment and in the seafood. The molluscan shellfish (i.e., oysters, clams, mussels, and scallops) are the species associated with shellfish poisonings. The absence of characteristics such as abnormal taste, smell, or appearance precludes sensory inspection for these toxins. Instead, ensuring seafood safety relies on testing seawater and the seafood itself The assays used to detect toxins in seafood have evolved as analytic methods and instrumentation have improved. The American Public... 

Red meat, shellfish and wholegrain cereals are good sonrces of zinc (most of the zinc is in the bran and germ of the cereal). Zinc is a component of more than 100 enzymes which carry ont a wide range of cellular functions and most of the zinc is present in mnscle. A deficiency of zinc is associated with slow wonnd healing, decreased appetite, loss of taste and smell and decreased immune function. 

In Japan, a wide variety of marine products, such as algae, molluscs, crustaceans, echinoderms, and fish have been consumed with relish from olden times. These food habits have stimulated many studies on the extractive components which may contribute to the taste of these products. Several comprehensive reviews on the subject are available (l-8 ) In order to avoid overlapping with them, special references are made in this review to those components whose roles in producing the taste of fish and shellfish have been examined organoleptically. 

Firstly, Takagi and Simidu (25) examined the correlation between the organic acid content of 9 species of shellfish and their taste, and found that the more palatable species were not necessarily richer in succinic acid, as exemplified by the hard clam, Meretrix lusoria. These results led them to conclude that succinic acid does not dominate the delicious taste of shellfish. Secondly, Konosu et al. (26) reported that the succinic acid content of the short-necked clam, Tapes japonica, when determined immediately after collection, was very low (20-40 mg/100 g of edible part) as compared with Aoki s value (330 mg), and that the flavor of a fresh sample was as good as that of a commercially available sample that had accumulated a large amount of succinic acid. 

Succinic acid is an umami-tasting constituent of shellfish, as well as a kokumi-tasting substance in Japanese sake. It is sometimes added to Japanese sake and soy sauce to improve the taste quality. It is industrially produced from maleic acid by hydrogenation and subsequent purification. It is also approved as a food additive in Japan. Recently, an efficient fermentation method has also been studied.246... 

Ingestion of toxin-infected bivalve shellfish is the route of exposure. There is no reliable taste, smell, or color to detect contaminated shellfish. The toxin is not destroyed or inactivated by heating or cooking. 

The flavor of fish and seafoods is composed of taste-active low molecular-weight extractives and aroma-active compounds. The taste-active compoimds are more abundant in the tissues of mollusks and crustaceans than fish. The most important non-volatile taste components are fi-ee amino acids, nucleotides, inorganic salts and quaternary ammonia bases. Alcohols, aldehydes, ketones, furans, nitrogen-containing compounds, sulfur-containing compounds, hydrocarbons, esters and phenols are the most important volatiles is shellfish. Alkyl pyrazines and sulfur-containing compounds are important contributors to the cooked aroma of crustaceans. Furans pyrazines, and Lactones have been found in heat-treated seafoods. Dimethyl disulfide, dimethyl trisulfide, heterocyclic sulfiir-containing compounds (alkylthiophenes) have been found in most thermally treated crustaceans like prawn, crab, oyster, crayfish and shrimp (52). 

Since wood and coal tar creosotes are complex mixtures, techniques for relating apparent bioaccumulation or biomagnification in food chains to human health concerns are not well defined. Fish or shellfish directly exposed to coal tar creosote wastes will be tainted by offensive odors and tastes. Extracts of shellfish taken from the wharf of the biological station in St. Andrews and from Passamaquoddy Bay (both in New Brunswick, Canada) indicated contamination with creosote oil (Zitko 1975). Concentrations of creosote oil found were as follows ... 

Extracts of shrimps and other crustaceans are desirable as taste additives in foods that are to have shellfish character. In addition, a hydrolysate from fish myofibrils has been claimed to have a synergistic effect with antioxidants (Hatate et al., 1990). This has also been reported for a mixture of amino acids from krill (Seher and Lbschner, 1986). In one case the single amino acid, proline, has been used as an antioxidant in fish oil (Revankar, 1974). The precise mechanisms for the antioxidative or synergistic actions are not known. 

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