Coffee beans contain a large amount of antioxidants, which are subjected to various changes during roasting. In this study, antioxidant potential of raw and roasted to different degree (light, medium, dark) C. arabica and C. robusta coffee beans was evaluated by the four antioxidant assay methods, TPC, FRAP, TEAC, and DPPH˙.The obtained results revealed signifi cant differences between the coffee types, roasting degree, and antioxidant activity assessment methods. FRAP and TPC appeared to be the most appropriate methods for revealing the differences in antioxidant potential of different coffee types and the effects of roasting. The results obtained by these methods were in good correlation. ABTS and DPPH˙ methods are not enough sensitive for the determination of roasting degrees.In general, based on statistical data evaluation, antioxidant activity is more dependent on the coffee type than on the degree of roasting, however, the selection of analytical method may also be signifi cant.

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.

Vorlová L., E. Sieglová, R. Karpí‰ková, V. Kopfiiva: Cholesterol Content in Eggs During the Laying Period. Acta Vet. Brno 2001, 70: 387-390.The aim of this study was to determine the actual cholesterol content in the eggs of breeding hybrid Hisex Brown from a large scale poultry farm in dependence on the lay period. The eggs were collected during the whole lay period at 10-week intervals. The average content of cholesterol per egg increased from 153.45 ± 12.39 to 263.90 ± 14.83 mg. The lowest values (153.45 ± 12.39 mg) were found in eggs at the beginning of the lay period (P < 0.01). Thereafter the cholesterol content was rising at 10 th (180.26 ± 11.16 mg), 20 th (208.22 ± 18.19 mg) and the 30 th (263.90 ± 14.83 mg) week of the laying period. At the 30 th week of the lay it reached the peak. At the 40 th week (236.72 ± 26.23 mg) we recorded a mild decrease (P < 0.05), followed by no changes till the end of lay.Cholesterol content expressed per 100 g of egg yolk mass varied from 1185.76 ± 110.12 mg to 1549.80 ± 107.87 mg. Its highest concentration (P < 0.01) was found at the beginning of the lay period. At the 10 th and the 20 th week the cholesterol content decreased and increased in the 30 th week again (P < 0.05). Then the cholesterol content mildly decreased till the end of the lay period.At the beginning of the laying period the actual concentration of cholesterol per 100 g of yolk was the highest (P < 0.01) whereas the weight of eggs matter and yolk was the lowest. Our results indicate that the cholesterol intake from eggo in humans is not only dependent on the yolk weight consumed but also on the phase of the laying period. Egg yolk, egg matter, hens, Hisex Brown

The colour and viscosity of egg yolk are among major indicators assessed by consumers and food technology. This study attempts to evaluate the colour and viscosity of yolk in laying hens' eggs after the addition of dried beetroot (Beta vulgaris L. ssp. esculenta var. rubra) at the amount of 1% and 2% per feeding dose (in July and August 2012). The experiment was performed on 24 hens that were divided into three groups of 8 laying hens. The preparatory phase lasted one week (standard diet), followed by four weeks during which experimental layers received a diet enriched with beetroot. Then, all layers were fed a mixture without beetroot for the following four weeks. Eggs were collected during the whole period of 8 weeks. In total, 30 eggs from each group were subjected to analysis. The colour of eggs was determined using spectrophotometry, by the Colour-guide sphere spex portable colorimeter. The results showed a significant (P < 0.05) increase in value L* of yolk colour in experimental groups whereas values a* and b* (indicators of the international colorimetric scale CIELAB) did not vary significantly. Similarly, specific purity C* ab did not show a significant difference (P < 0.05) between the control and experimental groups. The egg yolk viscosity was lower in experimental groups compared to the control group but the difference was not significant. The addition of dried beetroot at the amount of 1 and 2% per feeding dose had no effect on colour and viscosity. This paper supported the null hypothesis that the addition of dried beetroot to the feeding dose at the amount of 1% and 2% has no effect on the colour and viscosity of egg yolk.

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