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Microbial contamination of paper-based food contact materials with different contents of recycled fiberFood Microbiology and Safety

Zuzana Hladíková, Kristina Kejlová, Jitka Sosnovcová, Dagmar Jírová, Adam Vavrouš, Stanislav Janoušek, Milada Syčová, Vladimír Špelina

Czech J. Food Sci., 2015, 33(4):308-312 | DOI: 10.17221/645/2014-CJFS

Recycled paper is commonly used in food packaging industry, especially for disposable products. The material coming into direct contact with food products must not represent a source of contamination for food in accordance with the Framework Regulation (EC) No. 1935/2004 containing the general requirements on all food contact materials. In the present study, the microbial purity of 31 paper-based materials with different contents of recycled matter (0-100%) was evaluated using a standard method based on the disintegration of paper. The results of the present study indicate the existing relation between the use of recycled fibers and the content of microorganisms. The increased amount of recycled fibers significantly increased the amount of bacteria in the paper samples. The highest content of microorganisms was observed in the case of paper with the highest recycled fiber content. Total counts of bacteria ranged from 5.0 × 101 to 1.2 × 105 CFU/g. Moulds were detected only in three paper samples. As the microorganisms present in food packaging may penetrate into foodstuffs (particularly those with high contents of water or fat) and have an adverse effect on end-consumers' health, microbial criteria for food packaging should be included into the EU legislation.

The "Breme" red onion: effects of home-storage methods on quercetin and quercetin-glycoside contentsFood Chemistry and Safety

Elena DOZIO, Alessandra BARASSI, Alessandro RAVELLI, Ilaria ANGELI, Franco LODI, Gian Vico MELZI d'ERIL, Massimiliano M. CORSI ROMANELLI

Czech J. Food Sci., 2015, 33(5):405-409 | DOI: 10.17221/622/2014-CJFS

The "Breme" onion is a red-skinned cultivar growing in the northwest Italy. To date, its nutrient composition has not been described. In this study, we quantified the contents of quercetin (Q) and its glycosides and we studied their stability in the dependence on the local home-storage methods storage at 4°C and freezing. Quercetin-3,4'-O-diglycoside (3,4'-Qdg) was the most abundant form, followed by quercetin-4'-O-diglycoside (4'-Qmg ) and Q. We observed the reduction in the contents of all the analysed flavonols after storage at 4°C and after storage in frozen state. No changes have been observed in the ratio Q/3,4'-Qdg + 4'-Qmg, as well as in 3,4'-Qdg /4'-Qmg between the fresh, stored at 4°C, and frozen onions. This could suggest an overall condition of instability, not the activation of a selective deglycosylation pathway. In conclusion, our study shows that the "Breme" onion is mainly rich in 3,4'-Qdg and that home-storage methods do not preserve the stability of some important health-promoting molecules.

INDEX OF VOLUME 33 (2015) AUTHORs INDEX, AUTHOR INSTITUTIONS INDEXIndex

editors

Czech J. Food Sci., 2015, 33(6):I-XII | DOI: 10.17221/8613-CJFS

Rapid detection of total nitrogen content in soy sauce using NIR spectroscopyFood Analysis, Food Quality and Nutrition

Jie XU, Furong HUANG, Yuanpeng LI, Zhe CHEN, Yong WANG

Czech J. Food Sci., 2015, 33(6):518-522 | DOI: 10.17221/229/2015-CJFS

A method for the rapid and nondestructive determination of total nitrogen content in soy sauce was explored. Prediction models were established using near-infrared spectroscopy combined with each of the following techniques: partial least squares (PLS), interval PLS, synergy interval PLS (siPLS), and backward interval PLS. Results showed that each improved forecast model was better than the PLS model. The siPLS method exhibited the best performance. The full spectrum of light soy sauce was divided into 20 subintervals. The combination of four subintervals, namely, 6, 11, 13, and 18, showed the best effect, with a correlation coefficient of 0.9977 and an RMSECV of 0.0198. The full spectrum of dark soy sauce was divided into 20 subintervals. The combination of three subintervals, namely, 14, 17, and 19, showed the best effect, with a correlation coefficient of 0.9818 and an RMSECV of 0.0640. Therefore, the siPLS method can realise a rapid and accurate detection of total nitrogen content in soy sauce.

Antioxidant activity and sensory changes of strawberry tree fruits during cold storage and shelf lifeFood Technology and Economy, Engineering and Physical Properties

Costantino Fadda, Paolo Antonio Maria Fenu, Giampaolo Usai, Alessandra Del Caro, Yolanda Matia Diez, Anna Maria Sanguinetti, Antonio Piga

Czech J. Food Sci., 2015, 33(6):531-536 | DOI: 10.17221/171/2015-CJFS

The influence of storage time on a range of quality parameters, in vitro antioxidant activity, and the sensory acceptability of fully ripe strawberry tree fruits packaged into polypropylene trays under plastic film was assessed. Fruits were stored at 0°C for 6, 12 or 18 days and then transferred to shelf life at 20°C for 2 days. The parameters most influenced by cold storage and shelf life were firmness, colour, and antioxidant activity. Firmness decreased significantly during storage and colour parameters showed a decrease in saturation. Significant increases in polyphenols and anthocyanins were registered during storage, with a resulting increase in total antioxidant activity. The sensory analysis demonstrated that fruits maintain an acceptable quality level for up to 1 day under shelf life conditions following 18 days of cold storage.

Free and bound 3-chloropropane-1,2-diol in coffee surrogates and malts

Veronika Divinová, Marek Doležal, Jan Velíšek

Czech J. Food Sci., 2007, 25(1):39-47 | DOI: 10.17221/735-CJFS

The levels are reported of the free 3-chloropropane-1,2-diol (3-MCPD), its bound forms, the recognised precursors of 3-MCPD, and the factors influencing its formation in 5 selected coffee surrogates and 18 malts in the Czech Republic. The coffee surrogates had the free 3-MCPD level in the range of < 9.0 to 32 µg/kg while the highest amount was found in roasted barley. In malts, the free 3-MCPD levels were similarly low (< 9.0 to 45 µg/kg) being the highest in roasted malts (16-45 µg/kg). Nevertheless, the values found in either surrogates or malts, calculated after normalisation to 40% dry matter content, did not exceed the European Union limit of 20 µg/kg adopted for soy sauces and acid-HVP. The risk for consumers could arise from the bound 3-MCPD, its elevated levels having been found in both coffee surrogates and malts. In coffee surrogates, the bound 3-MCPD levels varied between 145-1184 µg/kg product; the highest level was found in roasted barley. The bound 3-MCPD levels exceeded the free 3-MCPD levels 32 to 81 times. In malts, the bound 3-MCPD levels ranged from 4.0-650 µg/kg, the highest amount having been found in roasted malts (463-650 µg/kg). The bound 3-MCPD levels exceeded the free 3-MCPD levels 0.4 to 36 times.

Characterisation of antilisterial bacteriocin-like substance produced by Enterococcus mundtii

Kateřina Solichová, Ivana Složilová, Iva Jebavá, Barbora Uhrová, Milada Plocková

Czech J. Food Sci., 2012, 30(1):89-97 | DOI: 10.17221/278/2010-CJFS

The antilisterial activity of E. mundtii 1282 strain and its cell-free neutralised supernatant was observed against five persistent L. monocytogenes strains using the agar spot method. The enterococcal metabolite was consequently characterised as a proteinaceous substance - the bacteriocin-like substance, which was heat-stable at heating to 100°C for 30 min, stable at pH 2-12, and still active after eight-week long storage at 6°C and -20°C. The bacteriocin-like substance reached the highest activity of 6400 AU/ml after ten hours of cultivation of E. mundtii 1282 strain, when it was at the stationary phase of its growth. E. mundtii 1282 strain produced the bacteriocin-like substance: in BHI broth with pH 4-6, at the cultivation temperature 12-45°C, and in BHI broth with 1-6% (w/w) NaCl.

Preparation of mango (Mangifera indica L.) wine using a new yeast-mango-peel immobilised biocatalyst system

Sadineni Varakumar, Kondapalli Naresh, Obulam Vijaya Sarathi Reddy

Czech J. Food Sci., 2012, 30(6):557-566 | DOI: 10.17221/478/2011-CJFS

The preparation of mango wine by yeast-mango peel immobilised biocatalyst system by repeated batch fermentation was conducted and compared to free cells fermentation at 15, 20, 25, and 30°C. The operational stability of the biocatalyst was good as the ethanol concentrations (76.0-96.0 g/l) and productivities (1.53-3.29 g/l/h) were high, showing the suitability of the biocatalyst for even low temperature winemaking. The concentration of ethyl acetate was not above 40 mg/l in all cases, and higher alcohols were low (< 330 mg/l) in wine with immobilised cells indicating an improvement in the product compared to free cells fermentation. Amyl alcohols were proved to be temperature dependent and decreased with the decrease in temperature (262.48-146.83 and 239.74-184.34 mg/l) in the case of fermentation batches with immobilised and free cells, respectively, from 30°C to 15°C. Sensory evaluation revealed fruity aroma (7.9 ± 0.73), fine taste (7.7 ± 0.24), and the overall improved quality of the wines produced by the immobilised system.

Distribution patterns of polyphenols and alkaloids in instant coffee, soft and energy drinks, and teaOriginal Paper

Noelia MANCHÓN, Laura MATEO-VIVARACHO, Matilde D'ARRIGO, Ana GARCÍA-LAFUENTE, Eva GUILLAMÓN, Ana VILLARES, Mauricio Ariel ROSTAGNO

Czech J. Food Sci., 2013, 31(5):483-500 | DOI: 10.17221/443/2012-CJFS

A previously developed method of HPLC-DAD-Fl has been used for the determination of phytochemical profiles in different types of drinks: instant coffee, soft drinks, energy drinks, and different types of tea (green, white, black, and red tea). Using data on the concentrations of 20 main phytochemicals (phenolic acids, flavan-3-ols, flavonols, flavones, and alkaloids) it was possible to identify most of the sample types. Chlorogenic and caffeic acids, and caffeine are the main target compounds in instant coffee; in soft and energy drinks, only caffeine was found. Tea has a more complex phytochemical composition. Unfermented tea is mainly composed of flavan-3-ols and alkaloids, with a high caffeine concentration. Black tea is composed of alkaloids and low levels of flavan-3-ols, which are affected by oxidative reactions during the fermentation. Flavonols are present in lower concentrations in all kinds of teas. The identified phytochemical distribution patterns were used to correctly differentiate instant coffee, soft drinks, energy drinks, unfermented tea and fermented tea (within fermented tea, black tea from red tea can also be differentiated).

Influence of the origin on selected determinants of the quality of pork meat productsOriginal Paper

Bożena GARBOWSKA, Monika RADZYMIŃSKA, Dominika JAKUBOWSKA

Czech J. Food Sci., 2013, 31(6):547-552 | DOI: 10.17221/479/2012-CJFS

in recent years, great attention has been paid to the quality of eaten meat and its products. There have been launched a lot of promotional campaigns aimed at providing opportunities for the consumption of traditional products. Based on the experiment, a significantly higher protein content was found in sausages produced by large producers (24.73 ± 1.98%). The fat content was significantly higher in traditional ham (16.25 ± 14.47%), compared with local ham (4.38 ± 2.26%) and the mass (9.29 ± 5.25%). The samples of traditional and local ham had a significantly higher salt content (3.31 ± 0.72 and 2.90 ± 0.54%, respectively). No dye compounds were detected in any of the tested samples. There were no statistically significant differences in hydroxyproline and l‑glutamic acid content between traditional and conventional samples of meat products. Analysis of nitrate (V and III) showed a statistically significant difference in the average contents of these compounds. Significantly higher levels of nitrates were revealed only in traditional ham samples (12.60 ± 8.08 mg NaNO(V)/kg and 17.53 ± 27.91 mg NaNO(III)/kg of the product, respectively), wherein there was a large variation in the content of these compounds in the samples.

Influence of storage at 4°C on the stability of high hydrostatic pressure treated onionOriginal Paper

José L. VÁZQUEZ-GUTIÉRREZ, María HERNÁNDEZ-CARRIÓN, Amparo QUILES, Isabel HERNANDO

Czech J. Food Sci., 2014, 32(1):96-101 | DOI: 10.17221/471/2012-CJFS

The effects of refrigerated storage on the microstructure and physicochemical properties of high hydrostatic pressure (HHP) treated onion were evaluated. Onion was submitted to 100 MPa at 50°C or 400 MPa at 25°C for 5 min, and stored for 28 days at 4°C. Electron microscopy techniques and light microscopy were used for the microstructural study. Total soluble phenolics, soluble protein percentage, and shear force were also studied. HHP treatments affected the cell wall and membrane permeability, favouring the diffusion of soluble material to the apoplast. Storage at 4°C also caused important structural degradation in the HHP-treated samples, which was higher when 400 MPa at 25°C were applied and led to physico-chemical changes during the first week of storage. Interactions between phenolics and solubilised cell wall material or proteins could explain the decrease in soluble phenolics and proteins during storage.

Stability of fried olive and sunflower oils enriched with Thymbra capitata essential oilOriginal Paper

Maria G. MIGUEL, Maria D. ANTUNES, Abdulrahman ROHAIM, Ana Cristina FIGUEIREDO, Luís G. PEDRO, José G. BARROSO

Czech J. Food Sci., 2014, 32(1):102-108 | DOI: 10.17221/217/2013-CJFS

The stability of olive and sunflower oils for domestic uses after frying cow steak or only heating were evaluated in the presence or absence of the carvacrol-rich essential oil of Thymbra capitata. The treatments consisted of sunflower and olive oils either enriched with 200 mg/l of T. capitata oil or without it, heating at 180°C for 20 min, or frying 100 g cow steak at the same temperature and for the same period of time. In all assays, acid, peroxide, and p-anisidine values were followed over time. The fatty acid profile was estimated before heating or frying as well as at the end of the experiment. The results showed that the type of fat as well as the type of treatment (frying or heating) was determinant for the acid, peroxide, and p-anisidine values found. The presence of the essential oil also demonstrated to affect those values depending on the type of the oil as well as on the type of the treatment (frying or heating). In contrast, the fatty acid profile did not change greatly.

In vitro simulated digestion on the biostability of Hibiscus cannabinus L. seed extractOriginal Paper

Yu-Hua Wong, Chin-Ping Tan, Kamariah Long, Kar-Lin Nyam

Czech J. Food Sci., 2014, 32(2):177-181 | DOI: 10.17221/222/2013-CJFS

We investigate the biostability of phenolic acids from a kenaf (Hibiscus cannabinus L.) seed extract using an in vitro model simulating the physicochemical (pH, temperature and bile salts) and biological (gastric and pancreatic enzymes) gastrointestinal conditions. Some of the antioxidants in the kenaf seed extract were not relatively stable in the intestinal phase of the gastrointestinal tracts. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and total phenolic content (TPC) assays displayed similar trends as the biostability of phenolic acids, which decreased during the digestion process. The overall percentage loss of selected phenolic acids was 8.4-49.4% in the intestinal phase. For the overall in vitro digestion system, significant correlations between phenolic acids, total phenolic content (TPC) and antioxidant activity (DPPH) were obtained in all digestion phases with the exception of the gastric phase.

Potentials of probiotics in the treatment of food allergy - a reviewReview

Ami PATEL, Nihir SHAH

Czech J. Food Sci., 2014, 32(3):205-212 | DOI: 10.17221/200/2013-CJFS

Food allergy is an adverse immune response to some proteins in some foods. Probiotic, health promoting bacteria have gained much importance because of their innumerable benefits, particularly in the treatment of diarrhea, hypercholesterolemia, atopic dermatitis, eczema, and gastrointestinal disorders by strengthening the immune system. The current paper reviews recent advances made in the treatment of food allergy through employing probiotic or synbiotic therapy. The results of several reports are very promising suggesting probiotics can influence the immune system to curtail the allergic responses.

Effect of cow energy status on the hypercholesterolaemic fatty acid proportion in raw milkOriginal Paper

Jaromír DUCHÁČEK, Luděk STÁDNÍK, Martin PTÁČEK, Jan BERAN, Monika OKROUHLÁ, Jaroslav ČÍTEK, Roman STUPKA

Czech J. Food Sci., 2014, 32(3):273-279 | DOI: 10.17221/360/2013-CJFS

We evaluated the proportion of fatty acid groups, with an emphasis on hypercholesterolaemic fatty acids, in the milk of 25 Holstein cows during the 1st period of lactation in relation to their negative energy balance (NEB). Sampling of each cow's milk started on the 7th day after calving. Milk samples (n = 425) were collected at 7-day periods during the first 17 weeks of lactation. The proportion (%) of saturated (SFA), hypercholesterolaemic (HCFA), volatile (VFA), unsaturated (UFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids in the milk fat was determined. Body condition score and fat to protein ratio in milk were applied for precise determination of the NEB breakpoint during the observed period. The effects of parity, NEB, regression on lactation week and fat to protein ratio were evaluated using SAS 9.3. Milk contained a lower proportion of SFA as well as equally higher UFA (± 2.13%; P < 0.01) during the NEB period. The overcoming of NEB caused an increase in SFA, however, and simultaneously a significant decline in total HCFA (-1.86%; P < 0.01) as well as main MUFA (-1.81%, P < 0.05). The results document the necessity of increasing Holstein cow robustness to meet the production conditions in dairy farms in relation to the requirement of higher nutrient quality as well as the potential health benefits of cow's raw milk for consumers.

Evaluation of wheat/non-traditional flour compositeOriginal Paper

Taťana Hofmanová, Marie Hrušková, Ivan Švec

Czech J. Food Sci., 2014, 32(3):288-295 | DOI: 10.17221/311/2013-CJFS

We examine the nutritional effect of selected non-traditional grain samples added into wheat flour. In a form of flour, amaranth, quinoa, lupine, 5 hemp types, 2 teff types and 2 chia types were used for wheat flour substitution on a low and high level. Samples with amaranth and lupine flour showed the best improvement in terms of protein content (in the range between 21.1 and 26.0%). The highest total dietary fibre was found in lupine composites (7.1 and 9.8%). Hemp samples contained a significant amount of minerals in comparison with the control wheat sample (from 1.16% to 1.98%). According to the above-mentioned differences, flour composites containing single tested grains were distinguished by principal component analysis. All examined plant materials could be recommended for wheat flour fortification in terms of nutritional improvement. The addition of non-traditional flours partially changed both the volume and shape of laboratory prepared bread correspondingly to the type and added amount.

Antioxidant activities of two novel synthetic methylbenzenediol derivativesOriginal Paper

Yan Huang, Zhiwu Jiang, Xianyan Liao, Jianping Hou, Xinchu Weng

Czech J. Food Sci., 2014, 32(4):348-353 | DOI: 10.17221/283/2013-CJFS

2-(tert-Butyl)-5-methylbenzene-1,4-diol and 3-(tert-butyl)-5-methylbenzene-1,2-diol were synthesised by Friedel-Craft reaction of 2-methylbenzene-1,4-diol and 4-methylbenzene-1,2-diol, respectively, with tertiary butanol providing reasonable yields. The antioxidant activities of these two products, mother compounds and 2-(tert-butyl)benzene-1,4-diol were investigated and compared by means of 2,2-diphenyl-1-picrylhydrazyl radical and Rancim at test; 3-(tert-butyl)-5-methylbenzene-1,2-diol is the most potent antioxidant tested by using Rancimat test experiment. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging abilities of 2-methylbenzene-1,4-diol, 4-methylbenzene-1,2-diol and 2-(tert-butyl)benzene-1,4-diol are almost equal and more than twice as strong as 2-(tert-butyl)-5-methylbenzene-1,4-diol and 3-(tert-butyl)-5-methylbenzene-1,2-diol. The antioxidant activities of the five compounds evaluated by Rancimat test mainly depend on their steric synergist effects between the two phenolic hydroxyl groups in their molecules. The antioxidant activities of the five compounds mainly depend on how many 2,2-diphenyl-1-picrylhydrazyl radicals can be scavenged by one mole of them in 2,2-diphenyl-1-picrylhydrazyl test. One mole of 2-methylbenzene-1,4-diol, 4-methylbenzene-1,2-diol and 2-(tert-butyl)benzene-1,4-diol can scavenge four moles of 2,2-diphenyl-1-picrylhydrazyl radicals, but one mole of 2-(tert-butyl)-5-methylbenzene-1,4-diol or 3-(tert-butyl)-5-methylbenzene-1,2-diol can only scavenge two mole 2,2-diphenyl-1-picrylhydrazyl radicals because 2,2-diphenyl-1-picrylhydrazyl radicals are very bulky.

Purification and characterisation of the bacteriocin produced by Lactobacillus plantarum, isolated from Chinese pickleOriginal Paper

Fang Zhou, Hongfei Zhao, Fengling Bai, Piotr Dziugan, Yuen Liu, Bolin Zhang

Czech J. Food Sci., 2014, 32(5):430-436 | DOI: 10.17221/270/2013-CJFS

119 strains of lactic acid bacteria from Chinese pickle were tested for production of antimicrobial compounds (bacteriocins). Among them, strain C8 showed strongly antibacterial activity against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 8739. Strain C8 was identified as Lactobacillus plantarum based on phenotypical, physiological tests and 16S rDNA identification. The antibacterial substance produced by strain C8 was sensitive to protease but not affected by lipase and amylase and designated as bacteriocin C8. Bacteriocin was purified by salting-out, dialysis and Sephadex G50 column chromatography. Based on SDS-PAGE, bacteriocin C8 was 16.5 kDa in size, which was different from that of other bacteriocins and it might be a novel bacteriocin. Bacteriocin C8 showed a wide range of antimicrobial activity especially as it inhibited some Gram-negative bacteria. This bacteriocin was heat resistant (20 min at 121°C) and stable in the pH range of 3 to 6.

Risk analysis in drinking water accumulation

Jana Říhová Ambrožová, Jaroslav Říha, Jana Hubáčková, Iva Čiháková

Czech J. Food Sci., 2010, 28(6):557-563 | DOI: 10.17221/98/2010-CJFS

Drinking water is safe water, from the perspective of long-term use is does not cause any disease, pathogenic and hygienically unsafe microorganisms do not spread in it and customers enjoy its consumption. Drinking water is regarded as a foodstuff, therefore the known HACCP system can be used in the control system which can be applied not only directly to the final product, but also to the whole system of drinking water production, distribution, and accumulation. Even if there is no problem concerning the water processing and the technological line is well adjusted, the quality of drinking water is subsequently deteriorated by its transportation and accumulation. The condition and character of the operated distribution network and reservoirs are significantly and substantially related to the maintenance of the biological stability and quality of drinking water. This is well confirmed by biological audits of the distribution networks and water reservoirs. A significant fact is the negative influence of the secondary contamination by air in the reservoir facilities and the occurrence of microorganisms (fungi, bacteria) in free water and in biofilms. The findings obtained in the framework of biological audits were so alarming that the outputs of biological audits contributed to the reconsideration of the efficiency of the standard for the construction and design of water reservoirs and pointed out the necessity of its review.

Antioxidant capacity and antioxidants of strawberry, blackberry, and raspberry leaves

Lucie Buřičová, Mirjana Andjelkovic, Anna Čermáková, Zuzana Réblová, Ondřej Jurček, Erkki Kolehmainen, Roland Verhé, František Kvasnička6

Czech J. Food Sci., 2011, 29(2):181-189 | DOI: 10.17221/300/2010-CJFS

The total phenolic content (Folin-Ciocalteu method), free radical scavenging ability expressed as DPPH value, ferric reducing antioxidant capacity (FRAP), and oxygen radical absorbance capacity (ORAC) were determined in water extracts of leaves from Rosaceae family plants (Fragaria vesca L., Rubus fructicosus L., and Rubus idaeus L.). The antioxidant capacities of the extracts (in the order of the above mentioned methods) were 73.6-88.9%, 60.1-71.4%, 49.7-78.0% respectively, and 45.3-66.5% of that of green tea water extract. Further, the presence of 15 compounds (gallic acid, rutin, ellagic acid, caffeic acid, p-coumaric acid, quercetin, kaempferol, myricetin, quercetin-3-d-glucoside, ascorbic acid, (+)-catechin, (-)-epicatechin, epicatechingallate, epigallocatechin, procyanidin B1) was studied by HPLC-ECD and their antioxidant capacities were compared to the antioxidant capacity of the extracts. Out of the compounds studied, mostly (+)-catechin, ellagic acid, and (-)-epicatechin participated in the antioxidant capacities of the studied plant leaves water extracts. The antioxidant capacity of leaves infusions (determined by DPPH method) was lower than those of red wines and tea infusions, but comparable to the antioxidant capacities of white wines and fruit beverages.

Colour analysis and discrimination of laboratory prepared pasta by means of spectroscopic methods

Marie Hrušková, Ivan Švec, Hana Sekerová

Czech J. Food Sci., 2011, 29(4):346-323 | DOI: 10.17221/25/2011-CJFS

For the CIE Lab colour profile determination of laboratory prepared pasta, two sample granulations and two spectral methods were tested. Pasta was manufactured progressively from semolina, common wheat, and corn flour. Sufficient colour spectra ranges were ensured by means of fortification with 9 non-traditional cereals in the first case, 8 natural colorants in the second one, and with 12 gluten-free pasta recipes in the last case. Both factors (i.e. granulation and spectral method) were proved as statistically significant by the cluster, variance and principal component analyses. In the comparison of the effects on the pasta composition and the spectral method, the latter demonstrated a stronger impact on the pasta colour profile measured.

3-Chloropropane-1,2-diol fatty acid esters in potato products

Vojtěch Ilko, Zuzana Zelinková, Marek Doležal, Jan Velíšek

Czech J. Food Sci., 2011, 29(4):411-419 | DOI: 10.17221/468/2010-CJFS

The levels of 3-chloropropane-1,2-diol (3-CPD) and fatty acid esters in raw potatoes, potato flakes, instant mashed potatoes, 2 potato dumplings, 32 French fries, and 61 potato crisps are reported. In a majority of the samples, free 3-CPD amount was under the limit of detection (< 3 μg/kg) or under the limit of quantification (< 9 μg/kg). Higher concentrations of free 3-CPD were found in potato flakes (37 μg/kg) and seven samples of potato crisps (10.4-46.2 µg/kg).Low concentrations of bound 3-CPD were present in raw potatoes (2 μg/kg), potato flakes (18 µg/kg), mashed potatoes (38 µg/kg) and potato dumplings (10-13 µg/kg). Higher levels of bound 3-CPD occurred in fried potato products. The amount of bound 3-CPD in pre-fried French fries was 27-64 µg/kg, in fried French fries its content was 100-258 µg/kg. In potato crisps, the bound 3-CPD amount was 98-2201 µg/kg. A striking difference was observed between the levels of bound 3-CPD in crisps fried in rapeseed oil and in fractionated palm oil (palmolein). For that reason, the changes were studied of the bound 3-CPD levels in palm oil after heating and in blends of rapeseed and palm oil during frying. It was proven that the frying oils absorbed into the fried potato products represent the main source of bound 3-CPD.

Design of a method to evaluate yeasts to be used as starter cultures in dry-cured meat products

Eva M. Casado, Juan J. Córdoba, María J. Andrade, Mar Rodríguez

Czech J. Food Sci., 2011, 29(5):463-470 | DOI: 10.17221/41/2010-CJFS

Some yeasts are involved in flavour development of dry-cured meat products showing a positive impact on the generation of volatile compounds. The aim of this work was to design a method of routine analysis to evaluate the production of volatile compounds by yeasts to be selected as starter cultures. For this purpose, several variations of a minimum culture medium that included free amino acids, oleic acid, and α-ketoglutarate, incubated under similar conditions of water activity and pH as dry-cured meat products, were assayed. In these conditions, the representative yeast strains isolated from a dry-cured meat product were tested. The volatile compounds were analysed using Solid Phase Micro-Extraction and gas chromatography/mass spectrometry. In the designed media, the tested yeasts produced volatile compounds involved in flavour development of dry-cured meat products. In addition, all the strains showed the highest production of these volatile compounds in the complete minimum culture medium witch included α-ketoglutarate and oleic acid.

Antioxidant and antimicrobial activities of beet root pomace extracts

Jasna M. Čanadanović-Brunet, Sladjana S. Savatović, Gordana S. Ćetković, Jelena J. Vulić, Sonja M. Djilas, Siniša L. Markov, Dragoljub D. Cvetković

Czech J. Food Sci., 2011, 29(6):575-585 | DOI: 10.17221/210/2010-CJFS

We described the in vitro antioxidant and antimicrobial activities of ethanol, acetone, and water extracts of beet root pomace. Total contents of phenolics (316.30-564.50 mg GAE/g of dry extract), flavonoids (316.30-564.50 mg RE/g of dry extract), betacyanins (18.78-24.18 mg/g of dry extract), and betaxanthins (11.19-22.90 mg/g of dry extract) after solid-phase extraction were determined spectrophotometrically. The antioxidant activity was determined by measuring the reducing power and DPPH scavenging activity by spectrometric metod, and hydroxyl and superoxide anion radical scavenging activity by ESR spectroscopy. In general, the reducing power of all the beet root pomace extracts increased with increasing concentrations. The DPPH-free radical scavenging activity of the extracts, expressed as EC50, ranged from 0.133 mg/ml to 0.275 mg/ml. Significant correlation was observed between all phytochemical components and scavenging activity. 0.5 mg/ml of ethanol extract completely eliminated hydroxyl radical, which had been generated in Fenton system, while the same concentration of this extract scavenged 75% of superoxide anion radicals. In antibacterial tests, Staphylococcus aureus and Bacillus cereus showed higher susceptibility than Escherichia coli and Pseudomonas aeruginosa.

Yeast assimilable nitrogen in South Moravian grape musts and its effect on acetic acid production during fermentation

Mojmír Baroň

Czech J. Food Sci., 2011, 29(6):603-609 | DOI: 10.17221/259/2010-CJFS

We observed the content of yeast assimilable nitrogen in grape musts, its consumption by yeasts during fermentation, and acetic acid production. The experiments were performed in the years 2007 and 2008. The experimental variants involved 48 musts and wines originating fromSouthern Moravia. The data enabled to monitor the contents of yeast assimilable nitrogen in musts and to draw the general conclusion that these musts contain high concentrations of both ammonium ions and yeast assimilable nitrogen (124.4 mg/l and 257.8 mg/l, respectively), thus posing no danger of problems with the nutrition of yeasts in the course of fermentation. Also, the average production of acetic acid was low (215.8 mg/l); this indicated that in the majority of must samples without added nutrients, the course of fermentation was smooth and trouble-free. The results obtained confirm that the method of formaldehyde titration is universal and simple, thus it can be recommended for winemakers as a useful and efficient analytical tool.

Microbial transformation of citral by Aspergillus niger-PTCC 5011 and study of the pathways involved

Akbar Esmaeili, Shamila Rohany, Shila Safaiyan, Seyed Amir Zarei

Czech J. Food Sci., 2011, 29(6):610-615 | DOI: 10.17221/237/2009-CJFS

Citronellol and hydroxy citronellal are fragrance ingredients used in decorative cosmetics and fine fragrances. They have many applications in flavourings, extracts, foods, and drugs manufacturing. Their use worldwide is in the range exceeding 1000 metric tons per annum. Previous studies investigated the biotransformation of citral by the free cell method and immobilised cell method with Saccharomyces cerevisae. In this research, the microbial transformation of citral by the sporulated surface cultures method with Aspergillus niger-PTCC 5011 was studied. In experiments, A. niger was inoculated on solid media in conical flasks. The transformation took place for the periods of time of 6 days and 15 days. The results were analysed by the theoretical study, Fourier transform infrared spectroscopy, gas chromatography, and gas chromatography-mass spectroscopy. The major compounds produced in 6 days were acetone (26.2%) and hydroxy citronellal (37.0%), while the major compounds after the 15-day period were acetone (15.0%) and citronellol (36.0%). As citronellol has numerous commercial applications, the 15-day biotransformation period was found to be preferable.

A Comparative Study of the Analysis of Free Fatty Acids in Cheeses (Cow's, Ewe's and Goat's) with Different Ripening Times using NIRS: Intact Samples and Fat Extracts

I. González-Martín, J. M Hernández-Hierro, I. Revilla, A. Vivar-Quintana, R. Morón-Sancho, J. Salvador-Esteban

Czech J. Food Sci., 2009, 27(10):S105 | DOI: 10.17221/964-CJFS

Lipolysis is of great importance in the development of the aroma and flavour of cheese and one of the usual ways of measuring it is to assess variations in fatty acids. The relative proportions of fatty acids in milk fat depend on the animal species, the stage of lactation and feed regime, the ripening time and the climatic conditions and microbiological quality of the milk. GC-MS is the reference method for the determination of fatty acids in cheeses, but the technique involves long analysis times.

Effect of storage temperature on the quality of dry fermented sausage Poličan

Josef Kameník, Alena Saláková, Gabriela Bořilová, Zdeněk Pavlík, Eva Standarová, Ladislav Steinhauser

Czech J. Food Sci., 2012, 30(4):293-301 | DOI: 10.17221/284/2011-CJFS

The influence of different storage temperatures (5°C and 15°C) on the quality of vacuum-packed dry fermented sausage Poličan was determined. The salami mixture, finished salamis (the maturing period of 30 days), and salamis stored for 30, 60, 90, and 120 days were analysed. The analyses performed (physical/chemical, sensory, microbiological) found no differences in sensory properties or basic physical/chemical and microbiological parameters in the products after storage under different temperature conditions for 120 days. When stored at 15°C, the total content of biogenic amines in samples was higher than that for samples stored at 5°C with statistical differences P ≤ 0.05. If the principles of good manufacturing practice are observed at all phases of the technological process, the storage temperature of 15°C does not represent a risk as the consequent concentration of biogenic amines and polyamines remains extremely low.

Detection of genetically modified soya, maize, and rice in vegetarian and healthy food products in SerbiaOriginal Paper

Gordana Zdjelar, Zorica Nikolić, Ivana Vasiljević, Biljana Bajić, Dušica Jovičić, Maja Ignjatov, Dragana Milošević

Czech J. Food Sci., 2013, 31(1):43-48 | DOI: 10.17221/105/2012-CJFS

The presence of genetic modifications was analysed in a total of 100 samples of non-labelled vegetarian and healthy food products. The basic raw materials in the samples tested comprised maize, soya, and/or rice. The screening of all samples was performed using the primers for CaMV35S promoter. The positive samples from this initial screening were further subjected to the analysis of specific transgenic material to determine the type of GMO present with subsequent quantification. Roundup Ready soya was found in eight samples, but its content was below the limit of 0.9%. None of the analysed samples of food products contained GM maize and GM rice. Considering that the investigated samples were imported mainly from EU countries, it can be concluded that the control of GMOs is carried out systematically and in accordance with the Serbian GMO Law.

Influence of dietary fibre addition on the rheological and sensory properties of dough and bakery productsOriginal Paper

Jindřiška KUČEROVÁ, Viera ŠOTTNÍKOVÁ, Šárka NEDOMOVÁ

Czech J. Food Sci., 2013, 31(4):340-346 | DOI: 10.17221/352/2012-CJFS

Wheat, apple, potato, and bamboo fibres were applied at 1 and 3% content to bread wheat flour and these additions were studied for the quality of dough and bakery products characterised by farinograph parameters, laboratory baking tests, firmness, and sensory analysis. The addition of fibre caused a decrease of loaf volume, also a change of crumb colour and a slight increase of bread crumb firmness. On the other hand, the addition of fibre affected the farinograph parameters, significantly decreased the specific volume especially at 3% fibre (P < 0.05). A statistically significant difference (P < 0.05) in firmness was found out between products with added wheat and bamboo fibre. Statistically highly significant differences (P < 0.001) were found among the other pairs of products with fibre. The best sensory properties were detected when examining the products with an addition of wheat and potato fibre. The enrichment of bread with fibre at 1% or 3% increased the dietary fibre content in bread with slightly adverse effects on bread quality.

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