Beef boiled, aroma

Oxazoles have been found in relatively few cooked foods, although over 30 have been reported in coffee and cocoa, and 9 in cooked meat. Oxazolines have been found in cooked meat and roast peanuts, but not to any extent in other foods. 2,4,5-Trimethyl-3-oxazoline has been regularly detected in cooked meat [26], and when it was first identified in boiled beef [27] it was thought that the compound possessed the characteristic meat aroma however, on synthesis it was shown to have a woody, musty, green flavour with a threshold value of 1 mg/kg [28]. Other 3-oxazolines have nutty, sweet or vegetable-like aromas and the oxazoles also appear to be green and vegetable-like [28]. The contribution of these compounds to the overall aroma of heated foods is probably not as important as the closely related thiazoles and thiazolines. 

In the case of boiled beef the results of AEDA were compared with those of AECA. Table 16.4 indicates that they agreed except in three cases. The odour potencies of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-mercapto-2-pentanone and methional were more than one dilution step higher in AECA than in AEDA [56]. Most likely, portions of these odorants had been lost during concentration of the extract for AEDA. AECA was also used in studies on the aroma of pepper [55], coffee [57] and Camembert cheese [58]. 

Table 16.4 Potent odorants of boiled beef—comparison (AECA) with AEDA [56] of aroma extract concentration analysis...

Chang et al. (42). They Isolated and identified 2,4,5-triinethyl-3-oxazoline in boiled beef. This compound was described as having a "characteristic boiled beef aroma". Mussinan et al. (35) identified oxazolines and no oxazoles in their beef system. Peterson et al. (43) reported on the volatiles of canned beef stew. Both 2,4,5-trimethyloxazole and 2,4,5-trimethyl-3-oxazoline were present. The relative concentration of 2,4,5-trimethyloxazole was medium while for 2,4,5-trlmethyl-3-oxazoline was extra high. Lee et al. (44) identified 2-methyl-3-oxazoline, 2,4-dimethyl-3-oxazoline and 2,4,5-trimethyl-3-oxazoline in the volatiles of roasted peanuts. The latter two 3-oxazollnes were also identified in the volatiles of fried chicken (19). 

Boiled beef and pork differ in their aromas. Beef smells more intensely meaty, sweet-caramel-like and malty, whereas pork is stronger in sulphurous and fatty odour notes [21, 37J. According to Table 6.29, the pronounced odour notes of beef are caused by high concentration of furaneol (no. 1), 2-furfurylthiol (no. 2), 3-mercapto-2-pen-tanone (no. 3) and 2-methyl-3-furanthiol (no. 6). Omission experiments confirmed that these volatiles and in addition octanal, nonanal, (E,E)-2,4-decadienal, are the key odorants of boiled beef [21 ]. The higher concentration of the caramel-like smelling furaneol (no. 1) in beef than in pork is due to higher levels of its precursors glucose-6-phosphate and fructose-6-phosphate [37],... 

Kerscher, R., Grosch, W. (1997) Comparative evaluation of boiled beef aroma by aroma extract dilution and concentration analysis. Z. Lebensm. Unters. Forsch. 204. 3-6... 

Recent studies of photooxidized butter and butter oil identified by aroma extract dilution analysis, 3-methylnonane-2,4-dione, a potent volatile compound derived from furanoid fatty acids (see Section C.4) (Figure 11.7). Six different furanoid fatty acids were established as dione precursors, and were found in various samples of butter made from either sweet cream (116 76 mg/ kg), or from sour cream (153-173 mg/kg), or from butter oil (395 mg/kg). Similar precursors of the dione were identified in stored boiled beef and vegetable oils. This flavor defect arising by photooxidation of butter or butter oil is apparently different from the light-activated flavor in milk,that involves the interaction of sulfur-containing proteins and riboflavin. However, more sensory comparisons are needed to distinguish between these two flavor defects due to light oxidation. 

Dilution analyses were used to elucidate the potent odorants (Table 12.23) of boiled beef and pork and of the meat and skin of fried chicken. Omission experiments (cf. 5.2.7) show that octanak nonanal, (E,E)-2,4-decadienal, methanethiol, methional, 2-furfurylthiol, 2-me-thyl-3-furanthiol, 3-mercapto-2-pentanone and HD3F are the key aroma substances of boiled beef. These compounds are also present in boiled pork and chicken, but species-specific differences... 

Few researchers have examined the effects of different cooking methods on the aroma of cooked meat. MacLeod and Coppock [14] compared the aromas of boiled and roasted beef using SDE. They suggested that carbonyl compounds, sulfides, pyrroles, and pyridines were associated with roasted aroma, whereas benzenoids and furans may be associated with the desirable qualities of well-cooked boiled beef In the experiment we describe here, headspace adsorption on Tenax TA was used to compare the aroma profiles of pressure-cooked and grilled lamb muscle. 

A series of alcohols (C4 - Cll) were identified in the tail meat. Odor threshold concentrations were generally higher for alcohols than the aldehyde counterparts. Except for 1-pentanol, the remainder of alcohol peaks were very small and might not be significant in overall arctna of boiled crayfish tail meat. Josephson et al. (23-25) found l-octen-3-ol, an enzymatic reaction product derived from lipids, to be one of the volatile ccxnponents widely distributed in fresh and saltwater fish. The compound 2-butoxyethanol identified in crayfish tail meat (3) has been reported in beef products (26-27). GC aroma perception of standard 2-butoxyethanol gave a spicy and woody note, hence this compound could be an important flavor component of the boiled crayfish tail meat. 

Despite the acknowledged importance of these furan- and thiophenethiols and their disulfides in meat-like flavors, it is only recently that compounds of this type have been reported in meat itself (8-10). Grosch and co-workers (11) have suggested that the 2-methyl-3-furanthiol and its disulfide are more important in the aroma of boiled meat than in roast beef where alkylpyrazines, 2-acetyl-2-thiazoline and 2,5-dimethyl-4-hydroxy-3(2 -fiiranone make greater contributions. 

Thiazole and its derivatives are detected in foods such as coffee, boiled meat, boiled potatoes, heated milk and beer. Aroma extract dilution analyses show that among the compounds I-in in Table 5.22, 2-acetyl-2-thiazoline (II) contributes most intensively to the aroma of quick fried beef. Model experiments showed that cysteamine, formed by the decarboxylation of cysteine, and 2-oxopropanal are the precursors. It was also found that higher yields of II are obtained at pH 7.0 compared to pH 5.0. The intermediates in the reaction path to thiazoline II (Fig. 5.21) were identified as the odorless 2-(l-hydroxyethyl)-4,5-dihydrothiazole (a) and 2-acetylthiazolidine b), which are in tautomeric equilibrium, presumably with 2-(l-hydroxyethylene)thiazolidine (c) as the intermediate compound (Fig. 5.21). The intermediates a and b are oxidized to thiazoline II by atmospheric oxygen in the presence of catalytic amounts of heavy metals. It is assumed that the... 

The aroma of boiled pork is not as intensive as that of beef and the fatty note is more pronounced. The concentrations of the fatty smelling carbonyl compounds, e.g., hexanal, octanal and nonanal, are lower in pork, but in proportion to the concentrations of 2-furfurylthiol, 2-methyl-3-furanthiol and HD3F, they are higher than in beef. This difference appears to favor the intensity of the fatty note in the odor profile of pork. In chicken, the fatty notes become even more noticeable due to... 

G MacLeod, BM Coppock. A comparison of the chemical composition of boiled and roast aromas of heated beef. J Agric Food Chem 25 113-117, 1977. 

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