Dynamics of Trans Fatty Acids during Storage of Meat Cans03 November 2012
Research from the GNU The V.M. Gorbatov All-Russian Meat Research Institute of Rosselkhozacademia found that under certain conditions trans fatty acids in canned pork meat could be sharply reduced.
The research by Andrei B. Lisitsyn, Valentina B. Krylova, Andrei N. Ivankin and Tatyana V. Gustova also found that meat produced under gentle sterilisation conditions saw an increase in brassidic acid.
The results of the study were presented to the International Congress of Meat Science and Technology earlier this year in Montreal.
Trans-isomers of fatty acids can be generated naturally and during industrial hydrogenation. Trans-isomers are found in limited quantity essentially in all human organs and tissues (2.4-2.9 per cent) and in human breast milk (2.1-2.3 per cent). Their sources include dairy products, meat and fat of cattle .
The World Health Organization and world experts recommend the population to reduce the consumption of trans-fats because numerous research studies indisputably proved the detrimental effect of consumption of trans fatty acids with food even at trace quantities. Nowadays, a limit on trans-isomers content in combined oils of no more than 8 per cent  is established in Russia, while in the EU countries a limit is no more than 2 per cent.
In cannery industry, products are subjected to prolonged exposure to high temperatures that can lead to increase in harmful trans-isomers quantity. Reliable systematic data on the real content of trans-isomers of fatty acids in animal fat  and meat products are not available from the literature.
MATERIALS AND METHODS
Chromatography-mass spectrometry is an up-to-date method of quantifying of chemical substances allowing for identification of obtained peaks of individual substances according to their mass-spectra.
In this connection, the detection of trans fatty acids was performed using chromatography-mass spectrometry.
Meat cans from pork in pieces produced under various sterilization conditions were a subject of research. Trimmed pork with mass fraction of fat tissue no more than 30 per cent was used in cans production. The cans were sterilized under the drastic condition of sterilization with the value of the attained sterilizing effect F=18 conditional minutes and the gentle sterilization condition with the F value equal to 12 conditional minutes.
Meat cans were analyzed immediately after the thermal treatment and during storage.
RESULTS AND DISCUSSION
As a result of the research, trans fatty acids such as elaidic (C18:1 n9t) and brassidic (C22:1 n9t) were identified and quantified. Elaidic acid is a trans-isomer of oleic acid. Brassidic acid does not metabolize in a mammal organism and accumulates in various tissues. There are literature data that brassidic acid causes the failure of the cardiovascular system, infiltration of the skeletal musculature and myocardium, and hepatocirrhosis.
The dynamics of trans fatty acids content during the cans production and storage is shown in Fig. 1. The obtained data give the evidence of the effects of the sterilization condition on the brassidic acid content in the experimental samples of cans. For example, the sterilization of the product under the drastic conditions led to 1.6 times increase in the mass fraction of the acid. On the contrary, the gentle conditions of sterilization reduced the mass fraction of brassidic acid from 0.5 per cent to 0.13 per cent.
At the end of 7.5 months of storage, the decrease in brassidic acid was observed in cans produced under the drastic condition; its content was 42.9 per cent in relation to the content after sterilization. Under the gentle sterilization condition the increase in the brassidic acid content was noted, that at the end of the 7.5 months of storage equaled to 260 per cent in relation to the corresponding results after sterilization. However, mass fraction of brassidic acid in cans, which was equal to 0.18 per cent of the total quantity of fatty acids, didn't exceed the established norms for oils.
It can be seen from the data shown in the figure that elaidic acid was identified only after 1.5 months of cans storage. Moreover, the mass fraction of the acid in the cans produced under the drastic condition was 5 times higher than the corresponding indicator for cans produced under the gentle condition. It should be noted that at the end of the 7.5 months of storage elaidic acid was not identified. Apparently, a molecular of the acid elongates by two carbon atoms and no more double bonds are generated in it.
Simultaneously, at the end of the cans storage period, the increase in mass fraction of stearic acid (C18:0) was detected.
The obtained results suggest that the drastic conditions of sterilization cause the generation of brassidic acid in cans from pork and promote the intensive generation of elaidic acid after 1.5 months of storage.
The analysis of the dynamics of the fatty acid content during storage of cans showed their stable reduction which allowed to conclude that the quantity of detected trans-isomers in meat cans from pork pieces will not affect the health of consumers.
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