Czech Journal of Food Sciences, 2013 (vol. 31), issue 2
Applications of mesoporous silica materials in food - a reviewReview
Andrea Bernardos, Lenka Kouřimská
Czech J. Food Sci., 2013, 31(2):99-107 | DOI: 10.17221/240/2012-CJFS 
Mesoporous silica materials have been developed for some applications in the health field. These solids are used for the controlled release of bioactive molecules, as catalysts in the synthesis of essential nutrients, as sensors to detect unhealthy products etc., with many applications in food technologies. By combining mesoporous silica materials with food, we can create healthier products, the products that improve our quality of life. The development of mesoporous materials applied to food could result in protecting bioactive molecules during their passage though the digestive system. For this reason, the controlled release of bioactive molecules...
Differentiation between fresh and thawed chicken meatsOriginal Paper
Anna ŠIMONIOVÁ, Bo-Anne ROHLÍK, Tereza ŠKORPILOVÁ, Michaela PETROVÁ, Petr PIPEK
Czech J. Food Sci., 2013, 31(2):108-115 | DOI: 10.17221/127/2012-CJFS
Adulteration of fresh meat and its possible substitution with frozen and thawed meat represents a problem, since thawed meat has not only lower sensory qualities than fresh meat but also a lower price. Commercial enzymatic kits seem to be a solution to reveal such unfair practises and were applied to detect the activity of specific enzymes, citrate synthase, mitochondrial enzymes that are released from the organelles destroyed by frost. We determined, whether the meat of slaughtered chicken was fresh or frozen/thawed, and to provide convincing results. The absolute results vary with the type of meat and depend on the enzyme used. However, the enzyme...
Fatty acid composition of oil obtained from soybeans by extraction with supercritical carbon dioxideOriginal Paper
Stela Jokić, Rezica Sudar, Sandra Svilović, Senka Vidović, Mate Bilić, Darko Velić, Vlatka Jurković
Czech J. Food Sci., 2013, 31(2):116-125 | DOI: 10.17221/8/2012-CJFS
Soybean oil fractions were obtained by collecting the extract at different time intervals during supercritical carbon dioxide extraction. The extraction was performed at the following temperatures: 313, 323, and 333 K, and at pressures of 300, 400, and 500 bar. The triacylglycerol composition and concentration of fatty acids in soybean oil fractions was evaluated. The fatty acid and triacylglycerol compositions of soybean oil obtained with supercritical carbon dioxide was compared with the soybean oil extracted with n-hexane. The extraction temperature and pressure, did not influence the fatty acids compositions which, however, differed in...
Pistachio deterioration detected by X-ray absorptionOriginal Paper
Alexey Proshlyakov, Stavros Yanniotis, Jiří Blahovec
Czech J. Food Sci., 2013, 31(2):126-131 | DOI: 10.17221/101/2012-CJFS
The measurement of the absorption coefficient of X-rays in healthy and fungus infected pistachio kernels was the main objective of this work aimed at detecting the potential injury by insects and/or fungi in the kernel. It was found that the absorption coefficient in the injured parts is about half of that in the healthy parts. The absorption coefficient is also affected by the position in the kernel due to the variations in cell dimensions and the oil and moisture contents in the kernels.
Microwave drying behaviour of tomato slicesOriginal Paper
Soner Çelen, Kamil Kahveci
Czech J. Food Sci., 2013, 31(2):132-138 | DOI: 10.17221/30/2012-CJFS
The microwave drying behaviour of tomato slices was investigated experimentally to determine the effects of microwave power on the drying rate, energy consumption, and dried product quality in terms of colour, and a theoretical model was proposed to define the drying curves of tomato slices. The experiments performed with the microwave power of 90, 180, 360, and 600 W indicate that the drying time and the energy consumption decreased considerably with an increase in microwave power. The experiments also revealed that the drying rate shows first an increase and then a decrease during drying, and that the colour quality of the product deteriorates significantly...
Antioxidant activity of red beet juices obtained after microwave and thermal pretreatmentsOriginal Paper
Anton Slavov, Vasil Karagyozov, Petko Denev, Maria Kratchanova, Christo Kratchanov
Czech J. Food Sci., 2013, 31(2):139-147 | DOI: 10.17221/61/2012-CJFS
Pressed juices and water extracts from untreated, microwave pretreated, and thermally treated red beet were obtained. The highest total betalain content - 606.34 mg/100 g dry matter (DM) was found in pressed juice obtained after microwave pretreatment. The individual betalains in the pressed juice from untreated red beet were tentatively determined by HPLC. The most abundant betalain pigments were betanin (312.47 mg/100 g DM), vulgaxanthin I (104.08 mg/100 g DM), and isobetanin (71.28 mg/100 g DM). The antioxidant activity of the pressed juices and extracts was determined. The highest antioxidant activity - 10832.4 µmol ТЕ/l was found...
Antioxidative activity of five flavones glycosides from corn silk (Stigma maydis)Original Paper
Shun-Cheng Ren, Qing-Qing Qiao, Xiao-Lin Ding
Czech J. Food Sci., 2013, 31(2):148-155 | DOI: 10.17221/194/2012-CJFS
Five flavones glycosides (i.e., 2''-O-α-l-rhamnosyl-6-C-3''deoxyglucosyl-3'-methoxyluteolin, ax-5'-methane-3'-methoxymaysin, ax-4''-OH-3'-methoxymaysin, 6,4'-dihydroxy-3'-methoxyflavone-7-O-glucoside, and 7,4'-dihydroxy-3'-methoxyflavone-2''-O-α-l-rhamnosyl-6-C-fucoside) were successfully isolated from corn silk and identified. We evaluated their antioxidant activity among in vitro assay systems. Most of the flavones glycosides showed a high antioxidant activity in a lecithin liposome system, as well as a strong scavenging activity against radicals such as 1,1-diphenyl-2-picrylhydrazyl...
Characterisation of polyphenol oxidase from Melissa officinalis L. subsp. officinalis (lemon balm)Original Paper
Serap DOĞAN, Yasemin AYYILDIZ, Mehmet DOĞAN, Ümran ALAN, Mehmet Emin DİKEN
Czech J. Food Sci., 2013, 31(2):156-165 | DOI: 10.17221/288/2011-CJFS
Polyphenol oxidase (PPO) from Melissa officinalis L. subsp. officinalis (lemon balm) was partially purified by ammonium sulphate precipitation and dialysis; and then it was characterised in detail in terms of pH and temperature optima, thermal stability, kinetic parameters, and inhibition properties. Based on experimental results, it was found out that (i) the optimum pH and temperature values of PPO were 6.5, 4.0, and 8.5 and 40, 50, and 60°C for catechol, 4-methylcatechol and pyrogallol substrates, respectively; (ii) the best substrate was pyrogallol due to the highest Vmax/Km...
Determination of silicon in Czech beer and its balance during the brewing processOriginal Paper
Rudolf Cejnar, Oto Mestek, Pavel Dostálek
Czech J. Food Sci., 2013, 31(2):166-171 | DOI: 10.17221/65/2012-CJFS
Inductively coupled plasma mass spectrometry was used for the determination of silicon in beer samples from the Czech market and in brewing raw materials and semiproducts. The content of silicon in barley malt depended on the barley variety and growing region. The goal was to establish silicon concentration in Czech beer and to find out which processes are the most significant in terms of silicon concentration in beer. The silicon concentration in Czech beer ranged from 16 mg/l to 113 mg/l depending especially on two factors. Firstly, the silicon content in beer increased as the original wort concentration and increased secondly, during decoction mashing,...
Varietal differentiation of white wines on the basis of phenolic compounds profileOriginal Paper
Lubomír Lampíř
Czech J. Food Sci., 2013, 31(2):172-179 | DOI: 10.17221/270/2012-CJFS
The authenticity of grapevine varieties is a very important topic in the Czech Republic, where varietal wines is very important for wine drinkers. The wines from 7 grapevine varieties were investigated. Sixteen phenolic compounds belonging among hydroxybenzoic and hydroxycinnamic acids, stilbenes, and flavan-3-ols were analysed by HPLC method. The aim of this study was to find markers of varietal origin of wines among the phenolic compounds studied. The analytical parameters obtained were evaluated for this purpose by CVA (canonical varietal analysis) method. It proved to be successful in detecting the following grapevine variety authenticity markers:...
Differentiation of Lactobacillus species by ARDRAOriginal Paper
Kateřina Kšicová, Marta Dušková, Renáta Karpíšková
Czech J. Food Sci., 2013, 31(2):180-188 | DOI: 10.17221/125/2012-CJFS
The Lactobacillus species by 16S Amplified Ribosomal DNA Restriction Analysis (16S-ARDRA) was identified. Lactobacilli are bacteria often found in foodstuffs of both animal and vegetable origins. On one hand, they play an important role in the food spoilage and, on the other hand, they are used as starter cultures in food fermentation processes. The species-specific identification by traditional biochemical methods is time consuming and not always fully effective. Therefore, more efficient techniques are searched for. We focused on rapid identification of Lactobacillus isolates from different habitats. Forty-nine collection strains...
Effects of shading and growth phase on the microbial inactivation by pulsed lightOriginal Paper
Elizabeth Cudemos, Adriana Izquier, María S. Medina-Martínez, Vicente M. Gómez-López
Czech J. Food Sci., 2013, 31(2):189-193 | DOI: 10.17221/145/2012-CJFS
Pulsed light is an emerging technology that kills microorganisms using pulses of an intense broad-spectrum light. This work aimed to determine the effect of population density and microbial growth phase on its microbicidal efficacy. To this, Pseudomonas fluorescens cultures were grown, diluted to different population densities, flashed, plated, incubated, and enumerated, Also, cultures of P. fluorescens, Bacillus cereus, and Saccharomyces cerevisiae were taken at different growth phases, diluted to the same population density, flashed, plated, incubated, and enumerated. Microbial inactivation was lower at high densities,...
Biological activities of essential oils and methanol extracts of five Ocimum species against pathogenic bacteriaOriginal Paper
Soumen Saha, Tarak Nath Dhar, Chandan Sengupta, Parthadeb Ghosh
Czech J. Food Sci., 2013, 31(2):195-202 | DOI: 10.17221/234/2012-CJFS
The essential oils and methanol extracts of Ocimum basilicum L., Ocimum kilimandscharicum Guerke, Ocimum gratissimum L, Ocimum canum Sims, and Ocimum tenuiflorum L. (green type) were examined for their potential antibacterial activities. The chemical composition of essential oils of Ocimum species was analysed by GC-MS. The inhibitory effects of essential oils and methanol extracts were studied on two Gram-positive (Bacillus subtilis, Micrococcus luteus) and five Gram-negative (Pseudomonas aeruginosa, Shigella dysenteriae, Escherichia coli, Vibrio cholera, and Shigella...