Sweet aroma

Despite its unsaturated nature, benzene with its sweet aroma, isolated by Michael Faraday in 1825 [1], demonstrates low chemical reactivity. This feature gave rise to the entire class of unsaturated organic substances called aromatic compounds. Thus, the aromaticity and low reactivity were connected from the very beginning. The aromaticity and reactivity in organic chemistry is thoroughly reviewed in the book by Matito et al. [2]. The concepts of aromaticity and antiaromaticity have been recendy extended into main group and transition metal clusters [3-10], The current chapter will discuss relationship among aromaticity, stability, and reactivity in clusters. 

Propylene is a colorless, flammable gas with a slightly sweet aroma, bp -47.7°C, flash point -107.8°C, and ignition temperature 497.2°C. It is available in cylinders and tank cars and by pipeline. 

In the case of pineapples, the 12 odorants listed in Table 16.7 were dissolved in water in concentrations equal to those determined in the fruit [50]. Then the odour profile of this aroma model was evaluated by a sensory panel in comparison to fresh pineapple juice. The result was a high agreement in the two odour profiles. Fresh, fruity and pineapple-like odour notes scored almost the same intensities in the model as in the juice. Only the sweet aroma note was more intense in the model than in the original sample [50]. In further experiments, the contributions of the six odorants showing the highest OAV (Table 16.7) were evaluated by means of omission tests [9]. The results presented in Table 16.8 show that the omission of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, ethyl 2-methylbutanoate or ethyl 2-methylpropanoate changed the odour so clearly that more than half of the assessors were able to perceive an odour difference between the reduced and the complete aroma model. Therefore, it was concluded that these compounds are the character-impact odorants of fresh pineapple juice. 

Kreteks contain tobacco and 40% shredded clove buds. They have a pleasant, sweet aroma of cloves, but have such high levels of tar, nicotine, and CO, that smoking one is equivalent to smoking 20 light American cigarettes. Eugenol, the local anesthetic in cloves, permits the inhalation of the harsh smoke. 

There is increasing evidence that the interaction of lipids with the Maillard reaction is relevant to the generation of flavor in many cooked foods. For instance, the removal of lipids from coconut has been shown to cause flavor changes in the roast material (12). Uncooked coconut contained significant amounts of lactones as the main aroma components on roasting pyrazines, pyrroles and furans were also found in the aroma volatiles which added a strong nut-like aroma to the sweet aroma of the unroasted coconut. When ground coconut was defatted and then roasted, the sweet aroma due to lactones disappeared and the product possessed a burnt, nut-like aroma. A marked increase in the number and amount of Maillard reaction products, in particular pyrazines, was found. 

Bouquet Strong, heavy and warm with a spicy-sweet aroma. 

Aroma Sweet aroma compared with a herby camphoraceous note... 

Various Isopentyl-substituted pyrazines, such as 2-lsopentyl-3-methylpyrazine, 2-isopentyl-5-methylpyrazine, 2-isopentyl-6— methylpyrazlne, 2-i8opentyl-5,6-disiethylpyrazlne, 2-isopentyl-3,5-dimethylpyrazlne and 2-isopentyl-3,6-dimethylpyrazlne were identified from the thermal reaction of glucose and leucine (12). The formation mechanisms for these compounds may also involve the reaction of 3,6-dihydropyrazine with isovaleraldehyde, the Strecker aldehyde of leucine. Kltamura and Shibamoto (13) described 2-lsopen-tyl-5,6-dimethylpyrazlne as having a caramel-like, coffee and sweet aroma. Although isopentyl-substituted pyrazines have not yet been reported in cocoa, they could, if present, be very Important contributors to that characteristic aroma. 

When mushroom homogenates were incubated with surimi, enhanced plant-like aromas somewhat reminiscent of oysters were produced, and this treatment also resulted In the masking of some of the fish-like aromas of the surimi. Cucumber homogenates developed strong cucumber, cardboard-like aromas which appear to be contributed principally by 2-nonenal and 2,6-nonadienal. As a result, the cucumber homogenates caused undesirable and unbalanced aromas that did not suppress unpleasant fishiness. Watermelon fruit extracts behaved similarly, and also provided unbalanced sweet aromas to surimi. Tests to date have been limited to short-term incubations of crude enzyme preparations with surimi. Further exploration of more purified and controlled plant-based flavor-generating enzyme systems for the production of fresh seafood-like aromas, and especially those for the eight-carbon volatile aroma compounds, appear warrented. 

Raw meat has only a weak sweet aroma resembling serum, and a salty, metallic, bloody taste. However, it is a rich reservoir of compounds with taste properties and aroma precursors (24). Each meat has a distinct flavor characteristic. The flavors of distinct meat species or species-specific flavors are often carried by the lipid fraction (2S). For example 4-methyloctanoic and 4-methylnonanoic acids are specific to mutton while (E,E)-2,4-decadienal is specific to poultry meat. 12-Methyltridecanal has been identified as species-specific odorant in stewed beef, and is responsible for the tallowy and beef-like smell (26). The distinctive pork-like or piggy flavor noticeable in lard has in part been attributed to p-cresol and isovaleric acid (27,28,29). 

Vanillin is a white crystalline solid with a pleasant, sweet aroma, and a characteristic vanilla-like flavor. Chemically, it is the methyl ether of 4-hydroxyhenzoic acid, a ring compound that contains the carhoxyl (-COOH) group and the hydroxyl (-0H) group. Vanillin is the substance responsible for the familiar taste of vanilla, which has been used as a food additive and spice for hundreds of years. Vanilla was probably first used as a flavoring by the inhabitants of South and Central America before the arrival of Europeans in the sixteenth century. Spanish explorers brought the spice hack to Europe, where it soon became very popular as a food additive and for the flavoring of foods. Since that time, vanilla has become one of the world s most popular spices. 

Other distinguishing features Plant has a sweet aroma. 

Metabolic pattern of (-r)-carvone (93) is similar to that of (-)-carvone (93 ) in S. bottropensis. (-r)-Carvone (93) was converted by S. bottropensis to give (-r)-carvone-8,9-epoxide (96) and (+)-5a-hydroxycarvone (98a) (Figure 19.112). (-t)-Carvone-8,9-epoxide (96) has light sweet aroma and has strong inhibitory activity for the germination of lettuce seeds (Noma and Nishimura, 1982). 

Ethyl butyrate is responsible for the sweet aroma of pineapples. Other common esters include methyl butyrate, found in apples, and ethyl formate, an artificial rum flavor. Several perfumes use esters to impart a pleasant smell. For example, oil of jasmine contains benzyl acetate, a molecule found in the jasmine flower. 

Cambuci fiaiits are green, ovoid-rhomboidal, 4-6 cm in diameter fruits, with 1 to 4 seeds, a sweet aroma, but extremely sour taste (Figure 21.11). It is native to the Brazilian state of Sao Paulo and it is consumed mainly as juice, jellies, liqueurs, and ice creams (Kawasaki and Landrum 1997). The fruit contains quercetin, kaempferol, and ellagic acid derivatives (Genovese et al. 2008). 

Oat flakes are produced by the following processing steps the kernels (12-16% water content) are steamed and then the moisture content is decreased to 7-10% in 2-3 h by heating at 90-100 °C. The hull (fruit and seed coats) is removed, i. e., the kernel is polished. This is followed by repeated steaming, squeezing between drum rollers, and drying of the moist flakes till the water content is 10-11%. The yield is 55-65%. This hydrothermic process also inactivates the oat enzymes involved in offflavor development. (E,E,Z)-2,4,6-Nonadienal produces the cereal-like, sweet aroma of oat flakes. It has... 

The apple, which telongs to the rose family, Rosaceae, is a pome—a fruit consisting of firm, juicy, flesh surrounding a core that contains several seeds. It is a close relative of the pear and the quince. With atout 7,500 varieties grown worldwide and 2,500 varieties in the United States, size, sweetness, aroma, and crispness vary greatly from one variety to another, as does the color which ranges from Shades of red to yellow or green. 

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