Antiradical Potential of Food Products as a Comprehensive Measure of Their Quality.

Antiradical potential (ARP) is an important measure of food safety. In addition, it directly or indirectly affects the rate of occurrence of a number of human pathologies. Using a photocolorimetric analysis of DPPH (2,2-diphenyl-1-picrylhydrazyl) solutions, we estimated the antiradical potential of food raw materials, food concentrates, biologically active substances, and wild plants. We conducted approximately 1500 analyses of almost 100 food products selected from 11 food groups: vegetables, milk, meat, fish, cereals and bread, drinks (including tea and coffee), etc. With a confidence interval (CI) of 95%, the average values for animal products range from 15.87 to 18.70 ascorbic acid equivalents per gram of dry matter. For plant materials, the range is 474.54-501.50 equivalents when wild herbs are included and 385.02-408.83 equivalents without taking herbs into account. The antiradical potential of the biologically active substances we studied ranged from 706.84 to 847.77 equivalents per gram of dry matter, which makes it possible to use some of the components to repair products with low ARP values, for example, bread and baked goods, confectionery, milk and dairy products, carbonated drinks, and juice. In this study, a low ARP value is associated with a reduction in the shelf life of products and a deterioration in their organoleptic properties; therefore, we propose using ARP as an important reference for describing the quality of food products and raw food materials.

Sub-picosecond fluorescence evolution of amino-cyano-stilbenes in methanol: polar solvation obeys continuum theory without evidence of twisting.

The spectral evolution of fluorescence from 4-(dimethylamino)-4'-cyanostilbene (DCS) in methanol, and of two derivatives bearing either the anilino (ACS) or the julolidino (JCS) moiety, was measured by optical Kerr-gating with a time resolution of 0.35 ps. A special thin Glan polariser in the Kerr shutter allows high contrast without unnecessarily increasing the group delay dispersion. The emission band may thus be gated and observed even with highly fluorescent samples. The spectral dynamics consists of a continuous red-shift and narrowing with similar relaxation behavior throughout, i.e. between these two observables and the three compounds. This suggests that polar solvation is the common cause for spectral relaxation after 0.2 ps. The continuum model describes the dynamic Stokes shift quantitatively. Contrary to previous reports we do not find a temporary isosbestic point in the fluorescence of JCS, nor is there evidence for a dependence on anilino substituents. The crystal structures of DCS and JCS are provided.