Authors:D. Trbović, T. Polak, L. Demšar, N. Parunović, M. Dimitrijević, D. Nikolić, and V. Đorđević
With the aim to reinforce laboratory competence in the field of testing the quality of fish from aquaculture, a study on the precision of fatty acid (FA) analyses in fish meat and fish feed was undertaken. Different methods were performed in laboratories. In situ transesterification method and extraction of lipids from the fish were followed by capillary gas chromatography with flame ionization detection. The reproducibility (R) values of the majority of FAs were less than 3% of their absolute values. Differences in calculating ionization detector response factors and/or autoxidation caused by faulty sample-handling could lead to variation in quantification of FAs in fish, especially for FA C22:6n-3. Statistical analysis showed a significant correlation between the two laboratories' quantifications of FAs in fish and fish feed (Pearson's correlation coefficient; r = 0.987, r = 0.994, and r = 0.997; for fish Z [trout], fish Š [rainbow trout], and fish feed, respectively). Overall, adequate accuracy was obtained in this study. The proposed method provides a fast and efficient means of identifying fish and feed for quality control purposes.
Authors:B. Purar, G. Bekavac, Đ. Jocković, É. Toldi Tóth, L. Kálmán, E. Raspudić, and M. Dimitrijević
Corn reddening (CR) was observed for the first time in Serbia in 1957. After that, it occurred periodically, mainly in the region of Banat. In 2002 and 2003, a severe outbreak happened in late July / early August. Initial symptoms were the occurrence of a red-violet color on the leaves, leaf sheaths, husks and the bare portion of internodes. The symptoms typically appeared at the milk maturity stage and the discoloration was the most intensive at top leaves, around the main vein and along the edges, from leaf base to tip. Soon after the occurrence of the symptoms, the affected plants wilted, the foliage dried rapidly, the red pigmentation disappeared for a greater part and finally plant died off. The ears were underdeveloped and gummous and kernels were shriveled and unfilled.Several experiments were conducted to determine a possible connection between CR occurrence and the studied factors. Corn stunt spiroplasma was not identified in the CR-affected plants, and there was no apparent relationship between CR and soil fertility or nematode species identified in soil and plant samples. Insecticide-treated plots had lower CR incidence than untreated (control) plots, indicating that biotic factors could be involved.