2009_Book_FoodChemistry

12.9 Meat Aroma 607
(12.28)
Larger amounts of MT are released only on hydrolysis
of the lipids in the meat of ruminants,
but not from the lipids of prok and poultry meat,
as shown in Table 12.24. In fact, there are indications
that microoganisms present in the stomach
of ruminants produce MT which is then incorproated
into plasmalogens.
The MT concentration in the phospholipids of
bovine muscle increases with increasing age. The
Table 12.24. Release of 12-methyltridecanal (MT) on
hydrolysis of lipids from different animal species
Animal species Lipid (g/kg) MT (µg/g lipid)
Beef a 14–22 55–149
Beef b n.a. 44–63
Veal a 12 19
Red deer a 25 5
Springbok a 14 16
Pork a 15–19 1.3–2.7
Pork b n.a. 1.6
Chicken b n.a. 0.3
Turkey b n.a. 1.6
The samples were refluxed: a with HCl (1 h), b at pH 5.7
(4 h).
n.a.: not analyzed
Table 12.25. Comparison of the aroma substances of
raw (I) and cooked, lean mutton (II)
Compound
Amount (µg/kg)
4-Ethyloctanoic acid 255 217
4-Methyloctanoic acid 278 502
(E)-2-Nonenal 27 21
(E,E)-2,4-Decadienal 2.9 4.6
(E,E)-2,4-Nonadienal 1.4 3.8
(Z)-1,5-Octadien-3-one 0.8 2.1
4-Hydroxy-2,5-dimethyl
-3(2H)-furanone
(HD3F)
<50 9162
I
II
studies conducted until now indicate a linear relationship,
which could be of interest for the determination
of the age of beef.
Important aroma substances of raw and cooked
mutton are listed in Table 12.25. A special feature
is the two branched fatty acids, which are already
present in the raw meat and produce the “mutton”
odor. (E)-2-Nonenal and the other odor substances
from lipid peroxidation are also present
in not inconsiderable concentrations in the raw
meat. Only HD3F is formed during cooking.
12.9.3 Process Flavors
Aromas obtained by heating aroma precursors are
used in the aromatization of foods. An important
aim of process flavors is the production of
odor qualities similar to those of meat. This is
achieved especially on heating cysteine with ribose,
as shown in Table 12.26. Glucose is less effective
and rhamnose promotes the formation of
HD3F.
For economic reasons, attempts are made to replace
individual precursors with inexpensive materials,
e. g., a relatively inexpensive protein hy-
Table 12.26. Formation of relevant aroma substances
on heating cysteine with ribose, glucose or rhamnose a
Compound
Amount (µg/kg)
Ribose Glucose Rhamnose
2-Furfurylthiol 12.1 2.8 0.8
2-Methyl-3-furanthiol 19.8 1.9 0.8
3-Mercapto-2-pentanone 59.9 13.9 7.3
4-Hydroxy-2,5-dimethyl-
3(2H)-furanone (HD3F) 18.5 79.4 19,800
a Mixtures of cysteine (3.3 mmol) and the monosaccharide
(10 mmol) dissolved in phosphate buffer (100 ml;
0.5mol/l; pH 5.0) were heated to 145 ◦ Cin20min.