Template-Type: ReDIF-Article 1.0 Author-Name: G. Tirzitis Author-Workplace-Name: Latvian Institute of Organic Synthesis, Riga, Latvia Author-Name: D. Tirzite Author-Workplace-Name: Latvian Institute of Organic Synthesis, Riga, Latvia Author-Name: Z. Hyvonen Author-Workplace-Name: Latvian Institute of Organic Synthesis, Riga, Latvia Title: Antioxidant activity of 2,6-dimethyl-3,5-dialkoxycarbonyl-1,4-dihydropyridines in metal-ion catalyzed lipid peroxidation Abstract: Antioxidants with 1,4-dihydropyridine structure were investigated as a less harmful alternative to synthetic phenolic antioxidants in liposomes under conditions simulating food storage. The antioxidant activities (AOA) of 2,6-dimethyl-3,5-dialkoxycarbonyl-1,4-dihydropyridines possessing various side chain length alkyls (CH3 - C16H33) in ester moiety were tested in transition metal-ion catalyzed liposome peroxidation and compared with AOA of Trolox™ and Probucol™. The compounds with C2H5 - C4H9 residues in the 3,5-position ester moieties exert the most pronounced AOA. The AOA of tested compounds is associated with their ability to incorporate into liposomes. Keywords: 1, 4-dihydropyridines, antioxidants, metal-ion catalyzed peroxidation Journal: Czech Journal of Food Sciences Pages: 81-84 Volume: 19 Issue: 3 Year: 2001 DOI: 10.17221/6581-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/6581-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200103-0001.txt Handle: RePEc:caa:jnlcjf:v:19:y:2001:i:3:id:6581-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: I. Kubiš Author-Workplace-Name: Mendel University of Agriculture and Forestry in Brno - Department of Food Technology, Brno, Czech Republic Author-Name: I. Křivánek Author-Workplace-Name: Mendel University of Agriculture and Forestry in Brno - Department of Food Technology, Brno, Czech Republic Author-Name: S. Gajdůšek Author-Workplace-Name: Mendel University of Agriculture and Forestry in Brno - Department of Food Technology, Brno, Czech Republic Title: The relationships between the chemical, dielectric and sensory properties of Edam cheese during ripening Abstract: Proteolysis, dielectric properties and sensory data were measured during ripening of Edam type cheese (30% and 45% FDM). Cheese of different age (1-25 weeks) was analysed. Dielectric properties were used as a method for assessing proteolysis. Permitivity had significantly similar continuance as pH 4.4 total soluble N, both in opposite to sweet milky taste, during ripening period. This paper offers dielectric properties as useful characteristics for assessing proteolysis in cheese. Keywords: Edam cheese, proteolysis, dielectric properties, permitivity, sensory analysis, ripening Journal: Czech Journal of Food Sciences Pages: 85-89 Volume: 19 Issue: 3 Year: 2001 DOI: 10.17221/6582-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/6582-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200103-0002.txt Handle: RePEc:caa:jnlcjf:v:19:y:2001:i:3:id:6582-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: P. Šmerák Author-Workplace-Name: 3rd Medical Faculty, Charles University, Prague; Czech Agricultural University, Prague, Czech Republic Author-Name: I. Bárta Author-Workplace-Name: 3rd Medical Faculty, Charles University, Prague; Czech Agricultural University, Prague, Czech Republic Author-Name: Z. Polívková Author-Workplace-Name: 3rd Medical Faculty, Charles University, Prague; Czech Agricultural University, Prague, Czech Republic Author-Name: J. Bártová Author-Workplace-Name: 3rd Medical Faculty, Charles University, Prague; Czech Agricultural University, Prague, Czech Republic Author-Name: M. Sedmíková Author-Workplace-Name: 3rd Medical Faculty, Charles University, Prague; Czech Agricultural University, Prague, Czech Republic Title: Mutagenic effects of selected trichothecene mycotoxins and their combinations with aflatoxin B1 Abstract: The authors focused on the amplification of data on the mutagenicity of selected trichothecene mycotoxins (T-2 toxin, vomitoxin) and their combination with aflatoxin B1,which is known to be a strong mutagen. Mutagenic activity was investigated using the Ames test in a prokaryote model at low doses (close to 0.1 LD50). Whereas the individual trichothecene mycotoxins (T-2 toxin, vomitoxin) did not show any mutagenic activity in the test systems mentioned, in combination with AFB1, or as a combination of all three mycotoxins, they showed a mutagenic effect significantly greater than AFB1 alone in the Ames test (in strain TA98 at all concentrations) as well as in the micronucleus test (combination of T-2 toxin with AFB1). Keywords: mutagenic activity, Ames test, micronucleus test, mycotoxins, aflatoxin B1, T-2 toxin, vomitoxin Journal: Czech Journal of Food Sciences Pages: 90-96 Volume: 19 Issue: 3 Year: 2001 DOI: 10.17221/6583-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/6583-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200103-0003.txt Handle: RePEc:caa:jnlcjf:v:19:y:2001:i:3:id:6583-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: I. Bohačenko Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: Z. Kopicová Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Title: Detection of olive oils authenticity by determination of their sterol content using LC/GC Abstract: The content of selected sterols as declared in the EU Commission Regulation was used to prove the authenticity of olive oils. A modified method using the preparative LC with silica gel packed column and gradient elution with three mixtures of hexane and diethyl ether was used to separate undesirable interfering compounds in the unsaponifiable fraction before the determination of sterols using GC. Model experiments based on the determination of D-7-stigmastenol and campesterol (addition of sunflower and soybean oils), or brassicasterol (addition of rapeseed oil) were used to verify that this method is capable of identifying adulteration of olive oils by additions of sunflower, soybean or rapeseed oils. An elevated content of these marker sterols, in comparison with their permitted contents, enables the identification of an addition of 5-10% of the above oils to the olive oil. This method was also used to evaluate the authenticity of five samples of olive oils from the SIAL exhibition (Paris) and ten samples of virgin olive oils obtained on thePrague markets. It was revealed that none of the samples showed the signs of adulteration. Keywords: olive oil, authenticity, adulteration, sterols, sunflower oil, soybean oil, rapeseed oil, liquid chromatography, gas chromatography, sterol determination Journal: Czech Journal of Food Sciences Pages: 97-103 Volume: 19 Issue: 3 Year: 2001 DOI: 10.17221/6584-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/6584-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200103-0004.txt Handle: RePEc:caa:jnlcjf:v:19:y:2001:i:3:id:6584-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: V. Šimánek Author-Workplace-Name: 1 LIBUŠE BALEJOVÁ and JITKA ULRICHOVÁ Author-Name: N. Škottová Author-Workplace-Name: 1 LIBUŠE BALEJOVÁ and JITKA ULRICHOVÁ Author-Name: J. Bartek Author-Workplace-Name: 1 LIBUŠE BALEJOVÁ and JITKA ULRICHOVÁ Author-Name: J. Psotová Author-Workplace-Name: 1 LIBUŠE BALEJOVÁ and JITKA ULRICHOVÁ Author-Name: P. Kosina Author-Workplace-Name: 1 LIBUŠE BALEJOVÁ and JITKA ULRICHOVÁ Author-Name: L. Balejová Author-Workplace-Name: 1 LIBUŠE BALEJOVÁ and JITKA ULRICHOVÁ Author-Name: J. Ulrichová Author-Workplace-Name: 1 LIBUŠE BALEJOVÁ and JITKA ULRICHOVÁ Title: Extract from Silybum marianum as a nutraceutical: a double-blind placebo-controlled study in healthy young men Abstract: In a randomized, double-blind, placebo-controlled study, the effect of an extract from Silybum marianum seeds (ESM, milk thistle extract) on lipid and liver parameters and the antioxidant capacity of serum was investigated in 29 healthy men aged 18-32 years. They received either 858 mg of ESM (531 mg silymarin complex calculated on pure silibinin), or placebo, daily for the period of 60 days. No side effects were found. A routine biochemical analysis of the serum was performed as a measure of lipid and liver metabolism. Positive trend towards decreased serum cholesterol level and HDL-cholesterol increase was observed in the ESM group as compared to the placebo group. The serum antioxidant capacity was significantly higher in the ESM group. The results suggest the use of ESM as a dietary supplement for hypercholesterolemia. Keywords: Silybum marianum, silymarin complex, double-blind, randomised placebo-controlled study, cholesterol, HDL, antioxidant status, nutraceutical Journal: Czech Journal of Food Sciences Pages: 106-110 Volume: 19 Issue: 3 Year: 2001 DOI: 10.17221/6585-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/6585-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200103-0005.txt Handle: RePEc:caa:jnlcjf:v:19:y:2001:i:3:id:6585-CJFS Template-Type: ReDIF-Article 1.0 Author-Name: J. Houšová Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Author-Name: K. Hoke Author-Workplace-Name: Food Research Institute Prague, Prague, Czech Republic Title: Temperature profiles in microwave heated solid foods of slab geometry: Influence of process parameters Abstract: A simple 1-D mathematical model for prediction of local temperatures in a layer of solid material during microwave heating (Houšová et al. 1998) and a sensitivity analysis were used to evaluate the influence of process and material parameters on vertical temperature profiles in a layer of material during heating. The results of calculations are presented in graphs and discussed. The incident microwave power and heat capacity and density of heated material are parameters with great effect on all local and average temperatures and local and average heating rates. The shape of temperature profile is influenced only to a small extent by a change in the value of applied microwave power and also in the value of heat capacity or density of heated material. The whole profiles shift to higher or lower temperature values when the incident microwave power is changing. The distribution of applied microwave power between the upper and bottom layer surface very much influences the shape of the profile and the values and position of the highest and the lowest temperature in the layer. Depth of penetration and thermal conductivity of heated material influence on the shape of temperature profiles and the temperature spread in the layer (evenness of temperature distribution). Effect of penetration depth also depends on the relation to the layer thickness - its effect increases with the increasing layer thickness. At the low values of penetration depth relative to the layer thickness, an uneven temperature profile is to be expected. Effect of thermal conductivity value on temperature profile depends on the time of heating. Because of a short time of microwave heating, the effect of this parameter on temperature distribution is smaller compared to the conventional heating methods. At the beginning of heating its influence is quite negligible. Temperature of the air surrounding the layer and intensity of heat exchange between the air and layer surface are parameters with only small local effect on temperature distribution. Keywords: microwave heating, temperature distribution, temperature profile Journal: Czech Journal of Food Sciences Pages: 111-120 Volume: 19 Issue: 3 Year: 2001 DOI: 10.17221/6586-CJFS File-URL: http://cjfs.agriculturejournals.cz/doi/10.17221/6586-CJFS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/cjf-200103-0006.txt Handle: RePEc:caa:jnlcjf:v:19:y:2001:i:3:id:6586-CJFS