Assessment of anthocyanins in grape (Vitis vinifera L.) berries using a noninvasive chlorophyll fluorescence method

Anthocyanins (Anths) in grape (Vitis vinifera L.) berries harvested at véraison from Pinot Noir and Pinot Meunier cultivars were assessed nondestructively by measuring chlorophyll fluorescence (ChlF) excitation spectra. With increasing Anth content, less excitation light was transmitted to the deeper Chl layers, and thus the ChlF signal decreased proportionally. By applying Beer-Lambert's law, the logarithm of the ratio between the fluorescence excitation spectra (log FER) from a green and a red berry gave the in vivo absorption spectrum of Anths, which peaked at about 540 nm. Absolute quantitative nondestructive determination of Anths for each berry was obtained by the log FER calculated for two excitation wavelengths, 540 and 635 nm (absorbed and not-absorbed by Anths, respectively) of ChlF at 685 nm. Over a range of skin colors going from green to purple, the relationship between the log [ChlF(635)/ChlF(540)] and the Anth concentration of berry extracts was fairly well fitted (r 2 = 0.92) using a power function. Reflectance spectra on the same berry samples were also measured, and Anth reflectance indices, which were originally developed for apples and table grapes, were derived. The log FER Anth index was superior to the reflectance-ratio-based index, but was as good as the color index for red grapes (CIRG) calculated from the whole visible reflectance spectrum. The proposed log FER method, applied by means of suitable portable devices, may represent a new, rapid, and noninvasive tool for the assessment of grape phenolic maturity in vineyards.     

Antioxidant,Antimicrobial and Genotoxicity Screening of Hydro-alcoholic Extracts of Five Serbian <Emphasis Type="Italic">Equisetum</Emphasis> Species

The hydro-alcoholic extracts of five Equisetum species, E. arvense L., E. sylvaticum L., E. fluviatile L., E. palustre L. and E. telmateia Ehrh., growing-wild in Serbia were evaluated for their genotoxicity, antimicrobial activity, antioxidant capacity and the results related to the total phenol content and HPLC flavonoid profiles. The total phenol content was 92–349 μmol expressed as equivalents of chlorogenic acid per g of dried plant material. Main identified compounds were kaempferol-, quercetin- glycosides and caffeic acid derivatives. E. telmateia extract showed the greatest antioxidant capacity. Almost all tested microorganisms demonstrated some degree of sensitivity to the examined extracts. All tested extracts at 62.5 μg/ml showed higher incidence of micronucleus formation than in the control sample. The obtained data allowed mutual comparison of examined species and their assessment as possible sources of antioxidants, antimicrobials and/or genotoxic substances.     

Seasonal stratification in fish culture and irrigation reservoirs: potential dangers for fish culture

Dual-purpose reservoirs for field irrigation and fish culture are characterized by the simultaneous (a) increase in standing crop biomass and feeds during the fish culture period and (b) decrease of water level due to irrigation. This management practice affects stratification, which in turn affects water quality and may affect the fish stocked. To study the limnology of dual-purpose reservoirs, an extensive sampling programme including automatic continuous recording and manual water sampling in deep and shallow reservoirs was carried out. This paper describes limnological changes during the week in which a 3 month long seasonal stratification ended and fish kills occurred. Management implications of stratification are also discussed. The data presented are the first continuous records of this process in this particular type of water body.