Czech Journal of Food Sciences, 2010 (vol. 28), issue 1
Safety and quality of farm fresh goat's cheese in the Czech Republic
Bohumíra Janštová, Michaela Dračková, Šárka Cupáková, Hana Přidalová, Markéta Pospíšilová, Renáta Karpíšková, Lenka Vorlová
Czech J. Food Sci., 2010, 28(1):1-8 | DOI: 10.17221/210/2008-CJFS 
The composition and selected physical and chemical parameters of 44 samples of fresh goat cheeses produced on a farm in the Czech Republic were determined. The following average values were obtained for the parameters analysed: pH 4.87 ± 0.14, titratable acidity (SH) 98.09 ± 4.93, dry matter 46.83 ± 1.57%, fat in dry matter 52.74 ± 5.24%, sodium chloride (NaCl) 2.08 ± 0.54%, and aw 0.979 ± 0.007. All samples showed excellent sensory characteristics and their compositions corresponded to those declared by the producer. Microbiological tests were used for the detection of Enterobacteriaceae...
Optimisation of ultrasonic-assisted protein extraction from brewer's spent grain
De-Song Tang, Ying-Juan Tian, Yuan-Zhe He, Lin Li, Song-Qing Hu, Bing Li
Czech J. Food Sci., 2010, 28(1):9-17 | DOI: 10.17221/178/2009-CJFS
Response surface methodology was employed to optimise the ultrasonic-assisted extraction of protein from brewer's spent grain. Three variables, namely the extraction time (min), ultrasonic power (W/100 ml of extractant), and solid-liquid ratio (g/100 ml) were investigated. Optimal conditions were determined and tri-dimensional response surfaces were plotted using mathematical models. The ANOVA analysis indicated that all the quantities determined, i.e. the extraction time, ultrasonic power, and solid-liquid ratio, had significant positive linear and negative quadratic effects on the protein yield. Optimum conditions for the extraction of protein were...
Anaerobic and aerobic beer aging
Jan Šavel, Petr Košin, Adam Brož
Czech J. Food Sci., 2010, 28(1):18-26 | DOI: 10.17221/161/2009-CJFS
Yellow, orange, red and brown pigments are formed by air oxidation of single polyphenols or by thermal degradation of sugars to caramels. Caramels increase their colours during anaerobic heating or decrease them by air oxidation. Epicatechin and caramel undergo reversible redox reaction followed by degradation and/or polymerisation at beer aging. That is why both of these colour compounds, besides acting as acid/alkali indicators, can also represent redox indicators that gradually become irreversible. These reactions are accelerated by transient metals or buffering solutions and are therefore more distinct in tap or brewing water than in deionised...
Nitrogen content, dietary fiber, and digestibility in algal food products
Ladislava Mišurcová, Stanislav Kráčmar, Bořivoj Klejdus, Jan Vacek
Czech J. Food Sci., 2010, 28(1):27-35 | DOI: 10.17221/111/2009-CJFS
The basic nutritional aspects and parameters of freshwater and marine algal food products are described. Blue-green algae (Spirulina pacifica, S. platensis), green algae (Chlorella pyrenoidosa), red algae (Palmaria palmata, Porphyra tenera), and brown algae (Eisenia bicyclis, Hizikia fusiformis, Laminaria japonica, Undaria pinnatifida) were used for this purpose. The ash content, total nitrogen, dietary fibers, and in vitro digestibility of the above-mentioned algal species were studied. The ash contents amounted to 8-11% (for freshwater) and 9-33% (for marine) of the weights of the algal samples. The total nitrogen contents...
Comparison of hazes in freshly bottled and aged beers by multiple angle turbidimetry
Petr Sladký, Robert Koukol
Czech J. Food Sci., 2010, 28(1):36-43 | DOI: 10.17221/218/2009-CJFS
The hazes of freshly bottled and aged pale lager beers determined with the 12° and 90° dual angle laboratory hazemeters and 10° to 90° range photogoniometer were compared and evaluated. The instruments were standardised in EBC formazin units. In freshly bottled beer, the forward (12°-25°) haze values were smaller approximately by a factor of three than the nephelometric (90°) values which yielded 0.33 EBC units. In aged beer, the forward haze was greater than the nephelometric one. Whereas the aged beer showed the greatest and the fresh beer the lowest intensity of scattered light, the formazin suspension intensity was in between. Due to the standardisation...
Influence of two sterilisation ways, gamma-irradiation and heat treatment, on the volatiles of black pepper (Piper nigrum L.)
Jana Sádecká
Czech J. Food Sci., 2010, 28(1):44-52 | DOI: 10.17221/1325-CJFS
The objective of this study was to investigate and compare the effects of ionising irradiation with different doses of gamma-rays (5 kGy, 10 kGy, and 30 kGy) versus the effect of heat sterilisation (dry steam, 130°C, 3 min) on the microbiological quality of powdered black pepper. Subsequently, the aim was to determine the impact of these sterilisation ways on the possible changes in the chemical composition and sensory quality (flavour) of black pepper essential oils. Methods of gas chromatography (GC/FID, GC/MS) were utilised for the evaluation of the essential oils compositions. The volatile constituents of black pepper extracts were studied with...
Antibacterial and antifungal effects of alcoholic extracts of 41 medicinal plants growing in Turkey
Ömer Ertürk
Czech J. Food Sci., 2010, 28(1):53-60 | DOI: 10.17221/144/2008-CJFS
The antibacterial and antifungal activities of crude ethanolic extracts of 41 traditional medicinal plant species belonging to 26 families were tested against four bacteria and two fungi: Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger. Of the 41 plants tested, 39 showed antimicrobial activity against one or more species of microorganisms. While the crude extracts from Nigellea arvensis did not show antimicrobial activity against the test microorganisms, Pistasia lentiscus showed only antifungal activity against A. niger. The most active antimicrobial...
Scavenging capacity of superoxide radical and screening of antimicrobial activity of Castanea sativa Mill. extracts
Jelena Živković, Zoran Zeković, Ibrahim Mujić, Senka Vidović, Dragoljub Cvetković, Žika Lepojević, Goran Nikolić, Nataša Trutić
Czech J. Food Sci., 2010, 28(1):61-68 | DOI: 10.17221/155/2009-CJFS
The superoxide radical scavenging and antimicrobial activity were examined of sweet chestnuts: seeds, peeled chestnut, brown seed coat, leaves, catkin, spiny burs, and chestnut bark as well as of Lovran's marrone leaves and grafted Italian marrone cultivar. Parts of chestnut were extracted under the same conditions with 50% ethanol as extractant and afterwards the dry extracts of the examined samples were obtained. The total phenolics and flavonoids contents were determined using standard spectrophotometrical methods. The capacity of the investigated extracts to remove radicals was evaluated by EPR method. The most efficient in scavenging *O-2...
Improvements in enzymatic preparation of alkyl glycosides
Dagmar Bilaničová, Vladimír Mastihuba, Mária Mastihubová, Jana Bálešová, Štefan Schmidt
Czech J. Food Sci., 2010, 28(1):69-73 | DOI: 10.17221/188/2008-CJFS
Three glycosides of middle chain aliphatic alcohols (hexanol and heptanol) were prepared by enzymatic glycosidation. The preparation of hexyl β-D-glucopyranoside was achieved in moderate yields via reverse hydrolysis catalysed by defatted meals from almond, apricot, and peach kernels. The apricot meal as a cheap source of β-glucosidase was found to have catalytic efficiency resembling to that of the almond meal. Hexyl and heptyl β-D-galactopyranosides were prepared from D-lactose by transgalactosidation catalysed by commercial β-galactosidases from Aspergillus oryzae in two-phase system. The improvement of the product yields...
The survival of Mycoplasma bovis at different temperatures
Marcela Vyletělová
Czech J. Food Sci., 2010, 28(1):74-78 | DOI: 10.17221/99/2009-CJFS
The survival of Mycoplasma bovis in milk samples was investigated at three storage temperatures (5°C, -30°C and -80°C) during 5 weeks. For the storage temperatures -30°C and -80°C, the respective samples were prepared weekly and those for culture by repeated defrosting. At 5°C the total number of M. bovis CFU/ml decreased from the initial of 1.13 × 107 CFU/ml to the final of 3.92 × 106 CFU/ml. The development in the frozen samples prepared for each week was as follow: (1) at -30°C - from the initial of 1.13 × 107 CFU/ml to 5.69 × 106 CFU/ml; (2) at -80°C - from the initial of 1.13 × 107...
Collection of food relevant microscopic fungi under the Czech national programme of protection of genetic resources of economically significant microorganisms - a short report
Alena Kubátová
Czech J. Food Sci., 2010, 28(1):79-82 | DOI: 10.17221/235/2009-CJFS
A unique project exists in the Czech Republic, namely the Czech National Programme of Protection of Genetic Resources of Economically Significant Microorganisms and Tiny Animals (NPPGR), which includes nineteen Czech collections of microorganisms (bacteria, fungi), viruses, and tiny animals. It is fully financed by the Ministry of Agriculture of the Czech Republic. Under this Programme, the Culture Collection of Fungi (CCF) in Prague maintains 293 fungal strains, 225 of which are food and feed relevant fungi (e.g. toxigenic Aspergillus flavus, Penicillium verrucosum, and Fusarium sporotrichioides). The main aims of the Programme are to...