Volatile Compound Markers in Beef Irradiated with Accelerated Electrons.

This study focuses on the behavior of volatile organic compounds in beef after irradiation with 1 MeV accelerated electrons with doses ranging from 0.25 kGy to 5 kGy to find reliable dose-dependent markers that could be used for establishing an effective dose range for beef irradiation. GC/MS analysis revealed that immediately after irradiation, the chemical yield and accumulation rate of lipid oxidation-derived aldehydes was higher than that of protein oxidation-derived aldehydes. The nonlinear dose-dependent relationship of the concentration of volatile organic compounds was explained using a mathematical model based on the simultaneous occurrence of two competing processes: decomposition of volatile compounds due to direct and indirect action of accelerated electrons, and accumulation of volatile compounds due to decomposition of other compounds and biomacromolecules. A four-day monitoring of the beef samples stored at 4 °C showed that lipid oxidation-derived aldehydes, protein oxidation-derived aldehydes and alkanes as well as alcohol ethanol as an indicator of bacterial activity were dose-dependent markers of biochemical processes occurring in the irradiated beef samples during storage: oxidative processes during direct and indirect action of irradiation, oxidation due to the action of reactive oxygen species, which are always present in the product during storage, and microbial-enzymatic processes. According to the mathematical model of the change in the concentrations of lipid oxidation-derived aldehydes over time in the beef samples irradiated with different doses, it was found that doses ranging from 0.25 kGy to 1 kGy proved to be most effective for beef irradiation with accelerated electrons, since this dose range decreases the bacterial content without considerable irreversible changes in chemical composition of chilled beef during storage.

Hemoglobin Derivatives in Beef Irradiated with Accelerated Electrons.

The efficiency of food irradiation depends on the accuracy of the irradiation dose range that is sufficient for inhibiting microbiological growth without causing an irreversible change to the physical and chemical properties of foods. This study suggests that the concentration of hemoglobin derivatives can be used as a criterion for establishing the limit for chilled beef irradiation at which irradiation-induced oxidation becomes irreversible. The express spectrophotometry method for estimating the hemoglobin derivative concentration shows a nonlinear increase in methemoglobin concentration from 15% to 50% in beef irradiated by accelerated electrons with the doses ranging from 250 Gy to 10,000 Gy. The monitoring of the hemoglobin derivative concentration for three days after irradiation shows nonmonotonous dependencies of methemoglobin concentration in beef in the storage time since the oxidation of hemoglobin occur as a result of irradiation and biochemical processes in beef during storage. The proposed method based on the quantitative analysis of the hemoglobin derivative concentration can be used to estimate the oxidation level for irradiation of foods containing red blood cells. The study proposes a model that describes the change in hemoglobin derivative concentration in beef after irradiation considering that oxidation of hemoglobin can be triggered by the direct ionization caused by accelerated electrons, biochemical processes as a result of bacterial activity, and reactive oxygen species appearing during irradiation and storage. This research throws light on the mechanisms behind food irradiation during storage that should be taken into account for selecting the optimal parameters of irradiation.

Estimation of doses absorbed by potato tubers under electron beam or X-ray irradiation using an optical fingerprinting strategy.

High-energy electron beam and X-ray processing of foods can be used for extending their storage life and for combating pests and pathogens. Several instrumental techniques are used to estimate irradiation doses in foods, but these methods are complex and laborious, require expensive equipment, and do not always allow to determine low doses. This study was aimed at developing simple methods for detecting irradiation in potato tubers and for dose estimation. We used a "fingerprinting" strategy that does not involve quantitation of any compound; instead, the rate of indicator reactions involving carbocyanine dyes is measured. The dye content was monitored by its near-infrared fluorescence intensity and visible-light absorption. Potatoes not subjected to treatment and those irradiated with different doses (10, 100, 1000, 5000, or 10,000 Gray) could be distinguished by linear discriminant analysis. Thus, the order of magnitude of the absorbed dose can be estimated with 89% ± 3% accuracy for a mixture of tubers of two potato varieties irradiated with an electron beam or with 95% ± 8% accuracy for one variety irradiated with an X-ray source.

Effect of electron and X-ray irradiation on microbiological and chemical parameters of chilled turkey.

The purpose of this work was to compare the effect of electron and X-ray irradiation on microbiological content and volatile organic compounds in chilled turkey meat. Dose ranges which significantly suppress the pathogenic microflora while maintaining the organoleptic properties of the turkey meat are different for electron and X-ray irradiation. According to the study it is recommended to treat chilled turkey using X-ray irradiation with the dose ranging from 0.5 to 0.75 kGy, while in electron irradiation permissible doses should be within 0.25-1 kGy. Three main groups of volatile compounds: alcohols, ketones, and aldehydes-were found in irradiated and non-irradiated samples of turkey meat. It was found that the total amount of aldehydes, which are responsible for the formation of a specific odor of irradiated meat products, increases exponentially with the increase in the absorbed dose for both types of irradiation. It was established that acetone can be used as a potential marker of the fact of exposure of low-fat meat products to ionizing radiation.