Seafood flavors

The relative ratios of alcohols and carbonyls for the six-, eight- and nine-carbon volatiles in fish (23-24) and oysters (26) parallel those encountered in cucumber fruits (37) and mushrooms (27, 56) if the two systems are combined. Therefore, the use of plant-based enzyme systems for the controlled generation of fresh seafood flavors and aromas has been under consideration in our laboratory as a means to overcome some of the self-inactivating problems associated with fish lipoxygenases. 

Exploratory Model Employing Suriml to Evaluate Plant-Based Seafood Flavor Generation... 

When pure, the product has a very powerful sulfurous odor, but at high dilution it develops a pleasant, grilled, smoky and very characteristic note (Ohloff and Flament, 1979). At a concentration of 1 ppm, it has a rubbery, burnt, sulfury, seafood flavor (Chemisis, 1995). The odor threshold in water is 5ppb (Tressl and Silwar, 1981), perceived as cooked meat with slight coffee note from 10 100 ppb. Tressl (1989) reported a threshold of 0.5ppb with a roast sulfur note at 10-50ppb. 

E,Z)-2,6-N. (violet leaf aldehyde) bp. 88 °C (1.3 kPa), LD50 (rat p.o.) >5 g/kg fatty-green odor of violet leaves in which it was first detected in 1925, ( ,Z)-structure assigned in 1944. It also occurs in vegetable flavors ( impact compound in cucumber), fruit flavors (guava, melon, mango), meat, and seafood flavors. For synthesis, see Lit.. ... 

IR-l-0cten-3-ol (Matsutake alcohol). CgH, 0, Mr 128.21, bp. 175 °C, [alg -20.2° LDjo (rat p.o.) 340 mg/kg. A typical mushrooms aroma constituent (olfactory threshold 1 ppb ) with an earthy-fungal odor impact compound in mushroom and Camem-bert flavor (see cheese flavor), but also occurring in many essential oils and flavors, e.g., in lavender, peppermint, rosemary, and thyme oil, as well as seafood flavors. Only the (/ )-enantiomer occurring in 90-97% enantiomeric excess possesses the pure fungus odor, the (S)-compound has a more vegetable-like odor. 

The contribution of bromophenols to seafood flavor and tainting has been clarified [58-59], It appears that bromophenols are natural components of seabed algae and other sea creatures (e.g., worms). They are considered to contribute to the characteristic desirable flavor of the seafood when at low levels. However, high levels of these bromophenols in the diet result in tainted product. Boyle et al. [59] found about 3 ppb was a normal bromophenol level in seafoods. However, levels as high as 38 ppb in herring, 30 ppb in salmon, and 100 ppb in shrimp have been fonnd. These levels would be expected to produce taints. Whitfield et al. [58] found 2,6-dibromophenol as the primary source of taint in prawn with 2- and 4-bromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol as secondary contributors. Whitfield et al. [60] identified various bromophenols as the source of an iodine-like taint in blackfish (Australian origin). 

Sulfur-containing heterocyclic compounds are associated with meaty characteristics. Two compounds with the most potent meaty impact include 2-methyl-3-furanthiol (1 ppt) and the corresponding dimer, -(2-methyl-3-furyl) disulflde (0.02 ppt) (18). Both substances have been identified in cooked beef and chicken broth and have a strong meaty quality upon dilution. The disulflde has a recognizable aroma character of rich aged-beef, prime-rib (15). Interestingly, both compounds are produced from the thermal degradation of thiamin (63). A related compound, 2-methyl-3-(methylthio)furan, is the character impact compound for roast beef (18). Other potent modifiers, such as 2-acetyl-2-thiazoline, impart a potent roasty, popcorn note, which enhances the meaty and roast flavor (64). 2-Ethyl-3,5-dimethylpyrazine and 2,3-diethyl-5-methylpyrazine also contribute potent roasty notes to roast beef flavor (65). A summary of character impact compounds for meat and seafood flavors is presented in Table 6. 

Three notable marine character-impact aroma exceptions are 5,8,11-tetradecatrien-2-one, which exhibits a distinct seafood aroma character described as cooked shrimp-like or minnow bucket (73). A second example is an extremely potent odorant in cooked shellfish, including shrimp and clam, identified by Kubota and coworkers (74) as pyrrolidino[l,2-c]-4//-2,4-dimethyl-1,3,5-dithiazine. This dithiazine contributes a roasted character to boiled shellfish and has the lowest odor threshold recorded to date, 10" ppt in water. 2,4,6-Tribromophenol and other bromophenol isomers have been associated with the ocean-, brine-, and iodine-like fiavor character in seafood such as Australian ocean fish and prawns. The source of the bromophenols is thought to be poly-chaete worms, which form an important part of the diet for many fish and prawn species (75). Finally, dimethyl sulfide is the character aroma of stewed clams and oysters (69). Representative structures for meat and seafood flavor impact compounds are shown in Fig. 6. 

Seafood. Citric acid is used in combination with other preservatives/antioxidants to lower the pH to retard microbial growth, which can lead to spoilage, formation of off-flavors, and colors on fish and other seafood products. 

Textured Soy Proteins. Textured vegetable proteins, primarily textured flours and concentrates (50% protein and 70% protein, dry basis, respectfully) are widely used in the processed meat industry to provide meat-like structure and reduce ingredient costs (3-6, 9-10). Available in a variety of sizes, shapes, colored or uncolored, flavored or unflavored, fortified or unfortified, textured soy proteins can resemble any basic meat ingredient. Beef, pork, seafood and poultry applications are possible 03, 4-7, 15, 19) Proper protein selection and hydration is critical to achieving superior finished product quality. Textured proteins have virtually no solubility and, thus, no ability to penetrate into whole muscle tissue Therefore, textured soy proteins are inherently restricted to coarse ground (e.g. sausage) or fine emulsion (e.g. weiners and bologna) products, and comminuted and reformed (i.e. restructured) meat products. None are used in whole muscle absorption or injection applications (2-4, 6, 11). 

Cereal flour, buckwheat flour, soy flour, seafood allergens, pork, sesame seeds, sunflower seeds, lupin, spinach, sarsaparilla root dust, cocoa, coffee dusts, green tea, egg protein, lactalbumin, milk powder, casein, honey, a-amylase, glucoamylase, pectinase, gluconase, pepsin, pectin, spices, carmine, flavorings... 

T. Ohshima, H. Ushio and C. Koizumi, in Flavor and Lipid Chemistry of Seafoods (Eds. 

It is often too expensive to have or maintain an inhouse descriptive sensory panel. Therefore, other ways of measuring flavor need to be developed. Off-flavor in many foods have been measured by using gas chromatography to assess the level of lipid volatiles associated with off-flavor development Chapters 5, 6, 9) such as hexanal or by direct chemical determination of thiobarbituric acid reactive substances Chapters 5, 6) as a marker of the degree of lipid peroxidation. A new method being tested for use in the assessment of food qu ity is impedance technology. This method is showing promise for use in the seafood industry Chapter 20),... 

Lemon juice has many uses in the food industry that other juices do not have because of its uniquely different composition in relation to other juices, except perhaps lime. Large quantities of lemon juice are used to enhance food flavors and to develop and balance the flavors of many food items, seafood being an outstanding example. Possibly only sugar and salt are used more extensively in the development and enhancement of food flavors. Lemon juice has also gained in popularity because of technological advances that now permit the manufacture of concentrated juices and the production of a frozen concentrate for lemonade. 

Seafood is one of the world s main protein sources. Among seafood, shrimp is consumed in large quantity throughout the world because of its pleasant flavor. 

Crayfish and crabs are two important crustacean seafoods in Louisiana, one of the most important seafood-producing states. Crayfish are about the size of a shrimp and look like small lobsters. Crayfish, also known as "crawfish" in Louisiana, have been regarded as one of the most important elements in Cajun cuisine, which is famous for its unique flavors. 

Most of the investigated processes to reduce allergenicity are purely on experimental basis but it is an important area of research for seafood allergy which has to be further explored. Furthermore, the challenge of maintaining the flavor and texture of seafood during these processes will be of importance. 

The development of both desirable and undesirable fishy flavors has long-been a concern to the seafood and fishery Industry (1-6). Oxidative processes occurring through enzymic and nonenzymlc mechanisms Initiate hydroperoxide formation In fish lipid systems that are responsible for the formation of the short chain carbonyls and alcohols which exhibit distinct flsh-llke flavors and aromas. Because the generation of fresh fish aroma compounds Involves some of the same polyunsaturated fatty acid precursors and oxidative pathways as autoxldatlon. It has been a tedious task to differentiate the mechanisms and aroma compounds... 

U. N. Wanasundara, and F. Shahidi, in F. Shahidi and K. K. Cadwallader, eds. Flavor and Lipid Chemistry of Seafoods, American Chemical Society, Washington, D.C.,1997. 

In the frying process, food, such as vegetables, meat, or seafood, is brought in direct contact with hot oil. The food surface becomes golden yellow to dark brown in color and develops a pleasant fried food flavor. 

---