Michael Lammers
Comparison of the aroma volatiles of wild boar meat and pork and cured products by gas chromatography / mass spectrometry
The aim of the first part of the present study was to describe the chemical compounds forming the aroma of wild boar (sus scrofa) meat for the first time. Therefore a dynamic headspace method was established to trap volatiles arising from the frying meat on Tenax®, elute and concentrate them to be suitable for GC/MS analysis.
Moreover meat of Australian wild pigs, conventional raced pigs and deer from New Zealand were tested in the same way. 57 volatile components were identified and quantified. Their forming pathways and contribution to the overall aroma were shown.
As expected the aroma profiles of pork and wild boar meat did not differ a lot, as the aroma of both kinds of meat basically depend on the same sorts of volatiles. A charac-ter impact compound of game flavor could not be identified. On the other hand there was a number of significant differences in the quantity of some volatiles, who allowed to distinguish typical characteristics of the different meats. A comparison of meat, iden-tical in fat and protein content could not be achieved. Therefore the absolute higher concentration of the products of lipidoxidation in pork and the higher amounts of com-ponents arising from amino acids in wild boar meat did not proof a race-depended difference in aroma. The smaller ratio of products arising from polyunsaturated fatty acids in the profile of wild boar meat became obvious only when looking at the relative amounts of lipid products. This is in agreement with the data of the fatty acid profile.
A difference in effective frying temperature has to be assumed as the amounts of water lost by the meats during frying differ widely. The forming of heterocycles with high aroma values, e.g. pyrazine, is favoured by higher reaction temperature and the higher level in proteins of game meat. Attention should be paid to the higher amounts of phenylacetaldehyd and methional while unraveling differences in aroma depending on race. Both of these substances are known to contribute to meat flavour. They derive from essential amino acids, whose total amount has been proofed to be 10 % higher in wild boar meat than in pork. Furthermore the amounts of 3-hydroxybutanon and buatric acid might be related to characteristic game flavor. Although an increase by enzymatic activity in any meat with the length of storage could be possible. Concluding from other studies on meat flavour it is likely that the typical aroma of wild boar meat relies more on quantity differences of volatiles than in qualitative ones.
In addition S-methyl-methanthiosulphonat has been described for the first time within the volatiles of meat.
In the second part of this study the volatiles of a number of pork products were ex-tracted by SPME and analyzed by gas chromatography/mass spectrometry, in order to find out whether feeding, processing condition or additional ingredients influence meat flavour. More than 40 volatiles were identified and could be shown to derive either from lipid oxidation, spices or smoke.
The hams examined in this study differed widely in regard to their individual circum-stances of production, still chromatograms were very similar. As the sensoric charac-teristics of the hams are obvious, they are likely to rely on delicate differences in the quantities of volatiles.
There are a couple of effects to be pointed out. Saturated aldehyds, main products of lipidoxidation, decrease when riping time increases. In contrast the amount of free carbonic acids increases with riping time. Due to its pleasant aroma and low odour threshold 5-butyldihydro-2(3H)-furanone should be considered as a quality parameter of dry cured hams. Benzene methanol seems to have a meaning for the products
made from meat of acorn-fed pigs, which is also supported by the data of dry cured sausage analyzes
Additional ingredients change the aroma profile of hams and sausages to a great ex-tent. Antioxidants improve stability and security of raw products but influence the amounts of volatiles with high aroma values arising from the lipids. Volatile compounds of spices are present in chromatograms with high area ratio and due to there sensoric characteristics contribute to aroma intensively.
To learn about delicate aroma differences caused by feeding acorns, standardized trials should be performed where additional influencing parameters will be excluded.
The given analytical equipment was reliable in identifying the major components of the different meat aroma. Still an increase in sensivity of the mass spectrometer would be helpful to gain deeper knowledge about minor components.
The trapping of volatiles on Tenax®, followed by elution and concentration is suscepti-ble for incorrectness. Though it allows a series of examinations from just one extract and achieves more information about the multicomponent extracts. On the other hand SPME is a cheap and potent technique, which can be modified easily. Heavy spiced meat products are not suitable for measuring the effect of different diets, unless a way of separating phytogenic volatiles is introduced.