Czech Journal of Food Sciences, 2010 (vol. 28), issue 4
The effect of natural antioxidants on the colour of dried/cooked sausages
Bo-Anne Rohlík, Petr Pipek, Jan Pánek
Czech J. Food Sci., 2010, 28(4):249-257 | DOI: 10.17221/345/2009-CJFS 
The colour changes caused by haem pigment oxidation were evaluated in the slices of dried sausages. To slow down these unwanted changes, several colourants and extracts from spices (rosemary, allspice, nutmeg, black pepper, clove, sandal wood, cochineal) were added to the meat product. The colour was evaluated using video image analysis (NIS Elements 2.0 software). The addition of antioxidants showed a positive effect on the colour stability and elimination of colour varieties in different parts of the dried sausage. These colour changes (decrease of redness a*) in cuts of dry sausages exposed to air and the light are influenced by the concentration...
Suppression of mould growth on dry sausages
Petr Pipek, Bo-Anne Rohlík, Anna Lojková, Ladislav Staruch
Czech J. Food Sci., 2010, 28(4):258-263 | DOI: 10.17221/121/2010-CJFS
The effects of two antifungal agents (natamycin, potassium sorbate) were compared on the mould growth on the surface of dry sausages (both heat treated and fermented). The mould growth was studied on fermented sausage Prešporska saláma and heat treated dry sausage Vysočina after the production and during the ripening and storage. Different samples were prepared: two natamycin treated (0.1% and 0.2%) and one potassium sorbate treated (2%), the control sample was not treated. All the samples were inoculated with spores of Penicillium nalgiovense and their germination and growth were monitored. An objective evaluation of the growth was carried...
Phytoestrogens in bovine plasma and milk - LC-MS/MS analysis
Anna Krajčová, Věra Schulzová, Jaromír Lojza, Ludmila Křížová, Jana Hajšlová
Czech J. Food Sci., 2010, 28(4):264-274 | DOI: 10.17221/138/2010-CJFS
Phytoestrogens belong to a group of polyphenolic plant metabolites which induce biological responses, based on their structural similarity to 17β-estradiol. In order to investigate the relationship between the levels of these biologically active compounds and beneficial health effects, it is neccesary to quantify accurately their levels in foods and biological fluids. In this study, HPLC-MS/MS method for the determination of isoflavones genistein, daidzein, and estrogenic metabolite-equol in bovine plasma and milk was optimised and validated. The method allowed low limits of detection: 5, 2.5 and 0.5 ng/ml for genistein, daidzein and equol, respectively,...
Antimicrobial and antioxidant properties of phenolic acids alkyl esters
Roman Merkl, Iveta Hrádková, Vladimír Filip, Jan Šmidrkal
Czech J. Food Sci., 2010, 28(4):275-279 | DOI: 10.17221/132/2010-CJFS
Some phenolic acids alkyl esters (methyl, ethyl, propyl, butyl and hexyl) and determine their antioxidant and antimicrobial activities were prepared. The antimicrobial activity against the tested microorganisms Escherichia coli DMF 7503, Bacillus cereus DMF 2001, Listeria monocytogenes DMF 5776, Fusarium culmorum DMF 0103, and Saccharomyces cerevisiae DMF 1017 was investigated and expressed by minimum inhibitory concentration (MIC) in the range of 1.2-20mM. The inhibitory activity of phenolic acids butyl esters was found to be higher than that of methyl esters (MIC below 1.25mM). The antioxidant activity of the selected...
Shelf life extension of liquid whole eggs by heat and bacteriocin treatment
Petr Miller, Melissa E. Haveroen, Kateřina Solichová, Roman Merkl, Lynn M. McMullen, Kamila Míková, Jana Chumchalová
Czech J. Food Sci., 2010, 28(4):280-289 | DOI: 10.17221/142/2010-CJFS
During a 15-month period, samples of commercially pasteurised liquid whole egg (LWE) were tested for the presence of spoilage microflora. The total bacterial counts were 2.2 ± 0.6 log CFU/g and total lactic acid bacteria (LAB) counts were 1.9 ± 0.6 log CFU/g. Enterobacteriaceae were detected in 2 samples. Out of the tested samples, 45 LAB were isolated and identified, with 30 strains identified as Enterococcus faecium, 12 as Enterococcus faecalis, and 3 as Lactobacillus paracasei subsp. paracasei. All strains, except 6 strains of E. faecium, possessed lipolytic activity. All the E....
Ability of phenolic acids to protect α-tocopherol
Zuzana Réblová, Petra Okrouhlá
Czech J. Food Sci., 2010, 28(4):290-297 | DOI: 10.17221/114/2010-CJFS
The ability of phenolic acids (gallic, gentisic, protocatechuic, syringic, vanillic, ferulic, caffeic, and sinapic; 600 mg/kg) to protect α-tocopherol was tested during the heating of sunflower oil on a hot plate set at 180°C and was compared with the ability of these phenolic acids to slow down the formation of polymerised triacylglycerols (TAG) in the same conditions. The half-life of α-tocopherol (calculated as the time needed for the α-tocopherol content to decrease to 50% of the original value) was extended significantly by gentisic, caffeic, and gallic acids (from 1.16 h to 1.77 h, 1.78 h, and 2.26 h, respectively), while the...
Profiles of S-alk(en)ylcysteine sulfoxides in various garlic genotypes
Jana Horníčková, Roman Kubec, Karel Cejpek, Jan Velíšek, Jaroslava Ovesná, Helena Stavělíková
Czech J. Food Sci., 2010, 28(4):298-308 | DOI: 10.17221/135/2010-CJFS
The contents of major S-alk(en)ylcysteine sulfoxides (namely alliin, methiin and isoalliin) were determined in a set of 58 various garlic genotypes (22 flowering plant morphotypes, 14 semi bolting plants and 22 scape absent morphotype plants), representing the garlic collection of the Allium gene bank in the Czech Republic. The plants were cultivated in four successive years (2005-2008) and analysed immediately after harvest and subsequently after eight weeks of storage at 5°C. The total content of the three cysteine derivatives in fresh samples varied considerably between 3.35 mg/g fresh weigh and 12.77 mg/g fresh weight, with the...
Comparison of Czech hop cultivars based on their contenst of secondary metabolites
Lukáš Jelínek, Michal Šneberger, Marcel Karabín, Pavel Dostálek
Czech J. Food Sci., 2010, 28(4):309-316 | DOI: 10.17221/65/2010-CJFS
Seven Czech hop varieties (dry hop cones) coming from the harvest of 2008 (Agnus, Bor, Harmonie, Premiant, Rubín, Sládek, and Saaz) were compared for their composition depending on their varietal differentiation. These cultivars were analysed for the contents of α- and β-bitter acids analogues, essential oils, and polyphenols. Hop essential oil constituents significantly contribute to the individual hop varieties. The dichotomous key for the authentication of Czech hop varieties was established based on some characteristic varietal markers.
Antioxidant activity of selected phenols and herbs used in diets for medical conditions
Diana Chrpová, Lenka Kouřimská, Michael Harry Gordon, Veronika Heřmanová, Iva Roubíčková, Jan Pánek
Czech J. Food Sci., 2010, 28(4):317-325 | DOI: 10.17221/129/2010-CJFS
The antioxidant capacity of some herbs used in dietology practice was determined by the DPPH free radical method, which was calibrated with ascorbic acid. Partially hydrophilic phenolic compounds are the most active compounds in plants, and therefore water was used as the extraction agent. Besides antioxidant capacity, the content of total phenolic compounds was also measured and a strong correlation between these two variables was found. The extracts of lemon balm (Melissa officinalis L.), peppermint (Mentha x piperita L.), oregano (Origanum vulgare L.), Greek oregano (Origanum heracleoticum L.), sage (Salvia...
Resistance of Listeria monocytogenes biofilms to disinfectants 326
Sabina PURKRTOVÁ, Hana TUROŇOVÁ, Tereza PILCHOVÁ, Kateřina DEMNEROVÁ, Jarmila PAZLAROVÁ
Czech J. Food Sci., 2010, 28(4):326-332 | DOI: 10.17221/153/2010-CJFS
We studied the optimal conditions for the biofilm development by Listeria monocytogenes on a model system represented by microtiter plates, and also for determined some effective disinfectant agents. Listeria monocytogenes ATCC 13932 and an industrial isolate of Listeria monocytogenes Lm-24 were compared as to their abilities to form biofilms. The starting concentration of the cells leading to the most reproducible results was 0.5 McFarland. The temperatures tested ranged between 8°C to 37°C, the optimal values to form biofilm in buffered peptone water (BPW) with 0.05% glucose were 25°C and 30°C. Under comparable conditions the persistent strain L....
Perfluorinated compounds: occurrence of emerging food contaminants in canned fish and seafood products
Petra HRÁDKOVÁ, Jan POUSTKA, Veronika HLOUŠKOVÁ, Jana PULKRABOVÁ, Monika TOMANIOVÁ, Jana HAJŠLOVÁ
Czech J. Food Sci., 2010, 28(4):333-342 | DOI: 10.17221/139/2010-CJFS
The contamination levels of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) and perfluorooctane sulfonamide (FOSA), which represent an important subgroup of the environmental contaminants known as perfluorinated compounds (PFCs), were examined in 35 imported canned fish and seafood products (tuna, sardine, cod liver) obtained from the Czech retail market in 2009. An analytical procedure was employed based on a fast and simplified sample preparation using activated charcoal clean-up followed by a LC-MS/MS determinative step. The content of PFOS, which was the dominating pollutant, ranged from 0.7 µg/kg to 12.8 µg/kg, PFOA...
70th birthday of Professor Pavel Kadlec, Dr.Sc.
Z. Bubník
Czech J. Food Sci., 2010, 28(4):343-344 | DOI: 10.17221/122/2010-CJFS