Odorants dry-cured ham

Flavor is an outstanding characteristic of dry-cured ham. The odor-active compounds of this product have been recently identified, and these data have shown the great importance of both lipid and amino acid derived compounds. To obtain samples with odor characteristics similar to those of dry-cured ham, several temperatures were applied to meat samples, and a mild temperature was selected. Compounds previously identified as dry-cured ham odorants were researched by SPME-GC-MS, and the effect of several factors on them was checked. The increase of sodium chloride content caused a general increase in aldehydes, except for 3-methylbutanal. The addition of sodium nitrite caused a general decrease, specially in straight-chain aldehydes. The addition of cysteine and proline on the odorants identified was less important. Reaction time influenced the odorants, with a marked effect on pentanal and hexanal. 

Aldehydes are by far the most numerous compounds identified as dry-cured ham odorants, with different odors (green, rancid, toasted) and thresholds in air ranging from 0.09 to 480 ng/L (Table 1). Most of them were identified in the first works focused on dry-cured ham volatile compounds (7,2). Aldehydes are essential for meat flavor (70), but large quantities in meat and meat products have been related to lipid oxidation and deterioration (77). The effect of several quality factors has been researched and it was found that the rearing system of pigs (S) and ripening conditions (7) influence on the contribution to odor and the content of some aldehydes. 

With regard to acids, odor thresholds are relatively large (except for 3-methylbutanoic acid) and usually appear at such concentrations that allow the identification by usual GC-MS. In fact, a large number of acids has been reported in numerous works focused on ham volatile compounds (7,2), although most of them have not been reported as dry-cured ham odorants. An increase in acids have been reported in spoiled hams (73). 

The aim of this work was to study the influence of salt content, the presence of sodium nitrite, the addition of cysteine or proline, and the reaction time on the most abundant compounds identified previously as dry-cured ham odorants of meat samples. 

Gas chromatography-mass spectrometry analysis was performed on an HP 5890 series II chromatograph (Hewlett-Packard) coupled to an HP 5973 mass spectrometer (Hewlett-Packard) and equipped with an HP-5 capillary column (50 m X 0.32 mm i.d., film thickness = 1.05 mm, Hewlett-Packard). The injector was maintained at 270 C. After injection, oven conditions were as follows 35 C for 10 min, 7 C min-1 to 150 C, 15 C/min to 250 C, 250 C for 10 min. The transfer line to the mass spectrometer was maintained at 280 C. Mass spectra were generated by electronic impact. A solution of n-alkanes (C5-C18) was analyzed under the same conditions to calculate lineal retention indices (LRI). Compounds were identified by comparing mass spectra and LRI with those of reference compounds analyzed under the same conditions. Only the compounds identified that were previously described as dry-cured ham odorants (6, 7) were taken into account. 

Among the different temperatures tested initially (4,25 and 95 °C), 4 C was chosen on the basis of odor characteristics. The higher temperatures (25 and 95 C) yielded samples without similarity to dry-cured ham odor. The odor of samples at 4 C showed some of the characteristics of dry-cured ham, although in... 

Ketones contribute to ham flavor with a wide range of notes and odor thresholds (0.03-1300 ng/L) (Table 1). In dry-cured ham, some of these ketones are affected by the rearing system of pigs (S), processing conditions (7) or microbial spoilage (73). 

Table 1. Odorants found in dry-cured ham (Parma and Iberian ham) ...

Sodium chloride content is closely related to ham quality, not only because of its direct effect on taste but also because of its effect on flavour development (75). The influence of sodium chloride content on volatile compound generation could be related to its effect on lipid-oxidation reactions, enzyme activity and microbial growth. As expected, salt content affected significantly a number of compounds described previously as dry-cured odorants (Figure 1) seven aldehydes and two acids. 

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