Abstractčelechovská o., l. malota, s. zima: entry of heavy metals into Food chains: a 20-year comparison study in Northern moravia (czech Republic). acta vet. Brno 2008, 77: 645-652.

The aim of this work was to determine antioxidant capacity of beverages containing black, white, and green tea extracts using the photochemiluminescence method, and to monitor its changes based on the storage temperature and time. Samples were stored at two different temperatures (refrigerated at 4°C and laboratory temperature 22°C), analyzed after opening of the original package, and consequently after 4 and 7 days. Results of the antioxidant capacity are expressed as the standard equivalents, that is, ascorbic acid in mmol/L. The highest mean value of the antioxidant capacity was found after opening of the original package in fruit-juice-enriched samples and totaled 9.793 mmol/L. This group revealed significant dependence (P < 0.05) not only on the storage time, but also temperature. In samples without added fruit juices containing preservatives the value was 0.428 mmol/L. This group showed significant dependence (P < 0.05) on the decrease of antioxidant capacity only when based on the storage time. Samples without fruit juices or preservatives showed significant decrease in the antioxidant capacity (P < 0.05) after 4 days of storage based on the storage time. The dependence on temperature was revealed only after 7 days of storage.

Fish fat belongs to highly specific nutritious elements especially due to its high content of polyunsaturated fatty acids. The aim of the present study was to determine the content of 2-thiobarbituric acid reactive substances in over-the-counter cold and warm marinades in which the base fish material consists of the Atlantic herring (Clupea harengus).Fifty six marinated fish products stored at refrigeration temperatures were analyzed before their expiration date. Their fat content was determined by means of the Soxhlet method and the TBARS validated fluorimetric micromethod.Lowest TBARS values were characteristic of warm baked marinades (1.17 ± 0.40 mg MDA/ kg muscle) and in case of cold marinades for the rolled herring fillets with pepper (5.03 ± 0.54 mg MDA/kg muscle) whereas the highest TBARS values were observed in warm cooked marinades (16.48 ± 4.22 mg MDA/kg muscle) and in roll mops sold over the counter (7.61 ± 3.87 mg MDA/kg muscle). The results showed that fat content is not always critical for herring TBARS determination in marinades.For the consumer safety it is essential to pay attention to cold marinades in brine sold over the counter and baked marinades in aspic before their expiration date. Marinated fish, fat, lipid oxidation, TBARS, baked and cold marinade

Nápravníková E., L. Vorlová, L. Malota: Changes in Hygienic Quality of Vacuumpacked Pork During Storage. Acta Vet. Brno 2002, 71: 255-262. Hygienic quality of boned vacuum-packed pork was monitored during storage by sensory, chemical, and microbiological methods. Pork was vacuum-packed into polyamide/polyethylene (PA/PE) foil 72 h after slaughter. Initial temperature did not exceed 9°C. The meat was stored at 2.5 ± 0.5°C in the dark for 35 days and samples for laboratory examinations were collected at days 14, 21, 28, and 35 to assess appearance, colour, odour, and characteristics of released meat juice, to determine pH and concentrations of ammonia and D-and L-forms of lactic acid, and to enumerate lactacidogenic bacteria. Lactobacillus curvatus and Lactobacillus xylosus were identified as the causative agents of meat spoilage using the API system. The results were subjected to correlation analyses. The shelf life of boned vacuum-packed pork varied between 21 and 28 days, depending on initial pH. The results of correlation analyses indicated that only ripe pork with the optimum pH = 5.8 to 5.95 is suitable for vacuum-packing. In addition to the lactacidogenic bacteria count (LAC), the shelf life can be estimated also from ammonia concentration (LAC/ammonia r = 0.9584, P < 0.05), pH (LAC/pH r = -0.9317, P < 0.05) and the concentration of D-lactate (LAC/D-lactate r = 0.9867, P < 0.01). Pork, vacuum packing, lactobacilli, ammonia, pH, lactic acidMeat spoilage is a complex process in which microorganisms present in the muscular tissue due to secondary contamination during processing are involved, and which depends on ambient temperature. The storage of meat is associated with changes in quality resulting from microbial activity, shift of pH, production of toxic substances, and aberrant odour (Huis 1996). Most prone to spoilage are foods with a high protein content, such as meat, poultry, fish, and milk, which have a high dietetic value, neutral, or lightly acid pH, and a high water content providing favourable conditions for bacterial growth (Huis 1996). Bauer (1995) demonstrated that enzymes of the muscular tissue and bacterial enzymes are involved in chemical changes (production of biogenic amines, changes in colour and fat) occurring during storage. The most important factors influencing the development and growth of spoilage microorganisms on raw meat in cold storage include the initial relative number of psychrotrophic flora and its growth dynamics at low temperatures. Qualitative and quantitative composition of the microbial population responsible for meat spoilage depend on pH, water activity, storage atmosphere, and among-species relations (Gould 1995). Dominant in the microbial population of vacuum-packed meat are lactacidogenic bacteria which participate in the development of an unpleasant odour. Dainty (1996) detected indol and hydrogen sulphide by gas chromatography and identified them as the cause of this sensory defect. The microbial activity results in the production of typical metabolit...

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