Małgorzata Rak

The appearance of the “oxidation band” in the fluorescence spectrum of anthocyanins is an indicator of oxidative deterioration of anthocyanins and can be a useful preliminary index of food freshness. Chokeberry ( Aronia melanocarpa ) fruit, rich in anthocyanins, can be subject to drying or lyophilization for domestic or industrial applications. The study was aimed at determining whether the measurement of fluorescence of dried chokeberry extracts can provide information on the extent of anthocyanin oxidation during prolonged drying at 60°C, and if fluorescence of fruit extracts can monitor anthocyanin oxidation during storage of the lyophilizates at various temperatures under air exposure. The increase in the fluorescence intensity of the extracts of chokeberry fruits or their lyophilizates at the “oxidation band” was a regular function of the time of fruit drying and the time of lyophilizate storage at 22°C and 37°C, confirming the usefulness of this parameter for estimation of oxidative changes in dried fruits and their lyophilizates. However, fluorescence of whole fruits, pulverized fruits and pulverized lyophilizate did not show a regular increase as a function of the time of fruit drying and lyophilizate storage, apparently due mainly to the effects of light scattering. The results point to the necessity of controlling the drying process of chokeberry fruits and storing their lyophilizates at ambient or higher temperatures with air access to avoid anthocyanin oxidation.

Meat is one of the most valuable foods in a healthy and balanced human diet. It is a very valuable source of protein with high biological value, performing many important functions in the body. The purpose of this study was to analyze the microbiological composition of selected wild game meat, i.e. wild boar, roe deer and deer, using microbiological methods to determine the coefficient of the total number of microorganisms (L) in meat during storage for 9 days and to control for the presence of pathogenic bacteria of the genus Salmonella, Yersinia, Escherichia and Listeria. The study showed that the total microbial count in all meat samples increased with storage time. After 9 days, deer meat had the lowest total microbial count, while roe meat had the highest. The analysis conducted for microbiological control confirmed the presence of pathogenic Escherichia and Yersinia bacteria in all samples tested.

The generation of hydrogen peroxide has been documented in various plant-based beverages, such as coffee, tea, herbal infusions and wine, as well in energy drinks containing ascorbate and in plant-based food. There are no data in the literature on the presence and generation of hydrogen peroxide in beer and strong alcoholic beverages containing plant material. This study aimed to examine whether beer and selected strong alcoholic beverages (brandy, whisky and fruit liqueurs) contain hydrogen peroxide. The presence of hydrogen peroxide was found in freshly opened brandy, whisky, liqueurs and most diluted beers; subsequent incubation in an air atmosphere led to the generation of hydrogen peroxide. The presence of the electron paramagnetic resonance (EPR) signal of the semiquinone radical and the generation of the superoxide radical demonstrated in selected alcoholic beverages by the superoxide dismutase-inhibitable reduction of Nitrotetrazolium Blue and oxidation of dihydroethidium are in agreement with the two-step mechanism of generation of hydrogen peroxide by the autoxidation of phenolics. These results broaden the list of beverages containing and producing hydrogen peroxide.