Lipid oxidation and 2-alchylcyclobutanones in irradiated traditional pork products

Irradiation is the treatment of food involving their exposure, either packaged or in bulk, to carefully controlled amount of ionizing radiation. Irradiation is considered a highly effective processing technology especially to decontaminate a wide range of food and for this reason it is a technique in constant spreading. Nevertheless irradiation can cause some chemical changes. This kind of treatment, indeed, can increase lipid oxidation and develop off-flavours. In fat-containing foods irradiation generates a family of molecules, namely 2-alkylcyclobutanones (2-ACB), originating from breakage of triglycerides. Considering furthermore that some reserchers underlined a potential toxicity of 2-ACB it is very important meanwhile to collect data concerning a wide variety of foods, wishing more investigations of this aspect. The aim of this investigation was to evaluate chemical effects of irradiation used as decontamination treatment on some typical Italian pork products: salame Milano, coppa and pancetta stesa. The research was focused in particular on the collection of preliminary data on the lipid oxidation (TBARS test) and the formation of 2-ACB. The three 2-ACB considered were 2-dodecylcyclobutanone (2-DCB), 2-tetradecylcyclobutanone (2-TDCB) and 2-(5’-tetradecenyl)cyclobutanone (2-TdecCB). The products at the end of maturation were portioned, packed under vacuum in transparent plastic bags and refrigerated. For each kind of product the following groups were created: the control group (Control, n=5), the group irradiated at 2 kGy (2kGy, n=5) and the group irradiated at 5 kGy (5kGy, n=5). The treatment was performed using electron beam. TBARS values were always lower than the suggested threshold for the appearance of rancidity off-flavours in fresh pork. They were in line with the results of previous investigations on commercial Italian pork products. In the condition of the present investigation, irradiation did not accelerate lipid oxidation. The high variability among the groups of samples seems to be due to an intrinsic variability of raw meat. Packaging is a critical factor affecting the lipid oxidation extent induced by irradiation. The three 2-ACB considered in this investigation were under the limit of detection (LOD) in all the pork products of Control groups. The irradiation dose 2kGy induced the formation of 2-ACB in all the three types of products. The irradiation dose 5kGy did not further increase the content of both 2-ACB in salame Milano and coppa whereas induced a significant increase (p≤0.05) of both 2-DCB and 2-TDCB in pancetta. In this product both 2-DCB and 2-TDCB increased in linear way. Probably, the higher total fat content (about 40%) in pancetta than in salame Milano and in coppa (about 30%) influenced the results. 2-TdecCB was found occasionally. In all the samples of Control groups, in these ones irradiated at 2 kGy and in samples of coppa irradiated at 5 kGy the 2-TdecCB was not detected. The limit of quantification of 2-TdecCB was higher than that of 2-DCB and 2-TDCB. 2-DCB and 2-TDCB have been confirmed to be useful markers of identification of irradiated fat-containing food, because. 2-TdecCB could be used as an additional marker. The conditions used during the treatment (vacuum packaging and refrigeration) seem influence both lipid oxidation and formation of 2-alkylcyclobutanones. The packaging can be considered a critical factor affecting the chemical quality of irradiated pork products.