The effect of two types of modified atmosphere (MA1: 69% N2, 25% CO2, 5%O2, 1% CO; MA2: 70% N2, 30% CO2) on changes in physical and chemical parameters (pH, aw - water activity, TVBN - total volatile basic nitrogen, TMA - trimethylamine, FFA - free fatty acids, PV - peroxide value, TBA - thiobarbituric acid) in muscle tissues of the silver carp was monitored in the study. The samples were stored at temperatures +2 ± 2oC for 18 days. Changes in gas volumes (CO2 and O2) in MAs were also monitored. CO2 levels increased in MA1 but decreased in MA2. At the end of 18 days of storage, a significantly (P < 0.01) lower water activity (aw) levels were found in samples packaged under MA1, in contrast to samples packaged under MA2 where water activity values showed considerable fluctuation. Variations in pH values in the two types of MA showed similar trends. Sample pH gradually decreased until day 9 of storage. On day 11, muscle tissue pH increased markedly and then began to decrease again. The overall decrease in pH values was more profound in samples packaged under MA1. TVBN and TMA levels in samples packaged under the two types of MAs remained almost identical until day 9 of the experiment. Later, however, significantly (P < 0.01) higher levels of both parameters were found in muscle tissues packaged under MA1. FFA concentrations in silver carp samples in MA1 were significantly lower (P < 0.01) throughout the experiment. The PV increased significantly in both muscle samples tested. Greater fluctuations in this parameter’s values throughout the experiment were observed in samples packaged under MA2. Faster rates of oxidation (P < 0.01) were found in samples packaged under MA1 starting on day 9. Maximum TBA values in MA1 and MA2 were observed on days 14 and 18 of the experiment, respectively. From the course of proteolytic and oxidative changes point of view, the more appropriate combination of gases for silver carp storage seems to be the mixture of 70% N2 and 30% CO2 (MA2), which allows for muscle storage of up to 9 days. We recommend TVBN as a suitable indicator of freshness, and TBA assay as a suitable indicator of the extent of oxidative processes.
The lipid peroxidation products measured as a tiobarbituric acid reactive substances and surface charge density of erythrocytes of rats intoxicated with different doses of methanol (1.5, 3.0, 6.0 g/kg b.w.) 6, 12, 24h and 2, 5, 7 days after intoxication were investigated. Furthermore, the blood methanol concentration and some hematological parameters were analysed. The analysed parameters were changed depending on methanol dose. The concentration of lipid peroxidation products was increased during 7 days and it was the highest after 24h and 2 days. The surface charge density was also increased. The highest elevation of this parameter was after 6h for a dose 1.5 and 3.0 g methanol/kg b.w. and after 24h for a dose 6.0 g/kg b.w. The number of erythrocytes and the mean erythrocyte volume were decreased during the first day of intoxication when the methanol concentration was the highest. The obtained results indicate the damage of erythrocyte membrane during the methanol intoxication.