Cocoa aroma, odorant

CnHieO, Mt 164.25, bpl9 kl>a 124-125 °C, df-7 0.9626, ng -7 1.5077, is a colorless liquid with a dry-flowery, lily-like odor. It has been identified in cocoa aroma and is prepared by a Grignard reaction of benzylacetone and methyl magnesium chloride. It is used in blossom compositions. 

Properties Colorless to yel. liq. nutty cocoa-like odor sol. in alcohol insol. in water 61 C m.w. 110.12 dens. 1.110 b.p. 60-61 C (29 mm) flash pt. 114 F ref. index 1.508 Toxicology Skin and eye irritant Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of NOx Uses Synthetic flavor for pharmaceuticals Features Sweet, cocoa-like flavor Regulatory FEMA GRAS ManuUDisthb. Advanced Synthesis Tech. http //www.advancedsynthesis.com] Aldrich http //www.sigma-aidrich.com] Degussa Flavors/Alfrebro Wutong Aroma http //WWW. wu-tong. com... 

Schnermann, P, Schieberle, P. Evaluation of key odorants in milk chocolate and cocoa mass by aroma extract dilution analysis. J. Agric. Food Chem. 1997,45, 867-872. 

The authors observed that an exhaustive list of all the chemicals present in coffee flavor had not yet been compiled, but they believed they had identified the components that are present at the higher ratio of weight, and those which principally control the odor note. Most of the substances identified were well-known compounds present in other roasted products as well, for instance in caramel sugar, cocoa, baked bread and—partially—even in wood tar. However, some of the chemicals detected were new and, obviously, characteristic of roasted coffee. Traces of methyl mercaptan, which was already known at that time and which smells even worse, were also detected in coffee aroma. Commenting on this observation, Reichstein and Staudinger note that it is generally known that many popular raw materials and synthetic perfume compounds owe their characteristic note, which is extremely pleasant to the olfactory sense, to their content of small quantities in additives which carry a rather unpleasant odor in themselves but prove very attractive in thinned solutions and in admixture with other oils. The authors tried to reconstitute coffee aroma, and only by combining over 40 of the substances extracted from coffee... 

The odor is powerful, choking when undiluted, but becomes tolerable in extreme dilution, almost pleasant fruity, fermented with a peculiar note resembling that of roasted cocoa or coffee (Arctander, 1967). For Motoda (1979), it is apple or malt. Fors (1983) mentions other odor descriptions as burnt, sickly for GC eluates, musty, fruity aromatic at 100°C becoming burnt cheese at 180°C. It is described as fermented, pungent, fruity at a sniffing port in a headspace/GC analysis of freshly roasted coffee (Holscher and Steinhart, 1992a). Like C.ll, it is a key component in a brew with a high aroma impact (Pollien et al., 1998). The flavor of the (R)-isomer is chocolate-like (Chemisis, 1971). 

D. of the types 1 and 2 are highly active secondary flavor compounds which are formed from aldehydes, hydrogen sulfide, and ammonia (1) or 1-pyrroline (2) when food is heated, i.e., from degradation products of lipids, amino acids and thiamin. D. occur especially in yeast extracts and meat flavor as well as in aromas of peanuts, cocoa, and seafoodsWidely distributed is thialdine (1 R, R R =CH3), CsH.jNSj, Mr 163.30, cryst. rusty and meat-like odor, mp. 46 °C. (C2-C4)-Alkyldimethyl- and dialkylmethyl-D. - exhibit interesting odor notes such as peanut, egg, cocoa, or fried onions, as does compound 2 (CgH NS2, Mr 189.33, mp. 40.5 °C), which occurs in yeast extracts, pork, and seafood aromas. 

C7H,iNS,Mr 141.23, bp. 180°C with an odor like tomato leaves, olfactory threshold in water 3 ppb. In contrast to many thermally formed, aroma-active thi-azoles (see also meat, coffee, and cocoa flavor) I. is a typical flavor compound of fresh tomatoes and is probably formed from leucine and cysteine. For synthesis, see Lit.. ... 

CaHjOj, Mr 126.11 crystals with a sweet-fruity caramel odor, mp. 164 °C (subl. at 93 °C) poorly soluble in water and alcohol. LD50 (rat p.o.) 1.4g/kg. M. is formed from lactose or maltose by the Maillard reaction , it was recognized as an odor substance in malt in 1894 and occurs, e.g., in "bread, "coffee, "cocoa, "meat and sake aroma, as well as in larch bark and pine needles. M. can be obtained from the latter by ex-... 

Two hundred and sixty-eight compounds were identified in this study as components of YEs, and they are listed by class in Table II. Sixty-seven of the compounds identified contained sulfur (75) and are listed in Table III. The 34 compounds identified for the first time as components of YEs are denoted by ( ) in Table III. Twenty-eight of the newly identified components of YE were detected in Sample C while seven were identified in Sample B. None could be identified from Sample A. Eighteen of the newly-identified representatives listed are thiazoles. Some of the thiazoles reported in this study, i.e., thiazole, 4,5-dimethylthiazole and 2,4-dimethyl-5-ethylthiazole possess meaty qualities at certain dilutions (76). 2,4-Dimethyl-thiazole, which has not previously been reported as a component of YE aroma, possesses a "meaty, cocoa" or "slmnky-oily" odor (76). Other thiazoles listed in Table III may be expected to contribute green, nutty and vegetable-like notes (76). 

The odorants of cocoa powder are listed in Table 21.24. A model (cf. 5.2.7) made by using the 24 aroma substances on the basis of deodorized cocoa powder reproduced the aroma of cocoa very closely. 

Some thiazoles occurring in nature possess an aromatic odor, for instance 4-methyl-5-vinylthiazole in the aroma of cocoa beans and passion fruit, 2-isobutylthiazole in tomatoes, and 2-acetylthiazole in the aroma of roasted meat. 

Chocolate represents a highly complex flavor system for which no single character impact has been identified. Vanillin and Furaneol contribute to the sweet, caramel background character of milk chocolate (57). 5-Methyl-2-phenyl-2-hexenal provides a deep bitter, cocoa note, and is the aldol reaction product from phenylacetaldehyde and 3-methylbutanal, two Strecker aldehydes formed in chocolate (58). 2-Methoxy-5-methylpyrazine and isoamyl phenylacetate have chocolate, cocoa, nutty and cocoa-like notes, respectively, and both are used in synthetic chocolate flavors (59). Systematic studies of key odorants in milk chocolate were performed using aroma extract dilution analysis however, character impact compounds unique to chocolate flavor were not reported (57,60). 

---