Czech Journal of Food Sciences, 2004 (vol. 22), Special Issue

Guaiacol formation in apple juice, effect of selected additives on Alicyclobacillus growth

I. Fabíková, M. Voldřich, R. Ševčík, P. Hönigová, M. Čeřovský

Czech J. Food Sci., 2004, 22(10):S246-S249 | DOI: 10.17221/10672-CJFS  

Disinfectant or card-board off-flavour formation was observed in the batch of pasteurised reconstituted apple juice. Aroma profile of products was analysed using SPME and GC/MS, guaiacol was detected in the apple juice sample as well as apple concentrate. Sporulating bacteria Alicyclobacillus acidoterrestris, which are able to growth in acidic conditions were isolated and identified as the cause of the off flavour formation. The possibilities of flavour formation inhibition using various additives were evaluated. The inhibitory effect of nisin, sulphur dioxide, benzoic acid and EDTA was followed. The best way of prevention is the sufficient...

Natural toxins in food crops and their changes during processing

J. Hajšlová, V. Schulzová, P. Botek, J. Lojza

Czech J. Food Sci., 2004, 22(10):S29-S34 | DOI: 10.17221/10606-CJFS  

Many food plant contain specific secondary metabolites which are classified as toxins or antinutrients for humans. In this short review main groups of these bioactive compounds are introduced, potential hazard posed for consumers and related regulatory aspects are mentioned. Substances which are currently of greatest concern are discussed in a greater detail. Phytoestrogens and glucosinolates are shown as compounds that may under certain conditions, exhibit health protecting effects, toxic glycoalkaloids, have been selected as an exampleof toxins occurring in staple crop, lectins and pyrrolizidine alkaloids represent as toxins responsible for recently...

Rapid, sensitive and selective analysis of acrylamide in cereal products using bromination and GC/MS/MS

C. G Hamlet, S. M Jayaratne, P. A Sadd

Czech J. Food Sci., 2004, 22(10):S290-S293 | DOI: 10.17221/10684-CJFS  

A rapid and sensitive method has been developed and validated for the analysis of acrylamide in cereal products. A kinetic study showed that a quantitative bromination of acrylamide in cereal extracts could be achieved within 25 min at room temperature. By using GC/MS/MS an increase in signal to noise of between 70 to 100 could be achieved for samples with minimal clean up compared to conventional selected ion monitoring. Results obtained from the analysis of a FAPAS cereal test material showed good agreement with the assigned value.

Effect of high hydrostatic pressure on the secondary structure of microbial transglutaminase

O. Menéndez, H. Rawel, U. Schwarzenbolz, T. Henle

Czech J. Food Sci., 2004, 22(10):S295-S298 | DOI: 10.17221/10685-CJFS  

Enzyme activity and corresponding secondary structure, measured by circular dichroism was analysed before und after treatment of microbial transglutaminase at different temperatures (40, 80°C) and pressures (0.1, 200, 400, 600 MPa). Irreversible enzyme inactivation was achieved at 80°C after 2 minutes at atmospheric pressure. Enzyme inactivation at 0.1, 200, 400, 600 MPa and 40°C followed first order kinetics. Increasing pressure reduced MTG activity, nevertheless the enzyme showed a residual activity of 50% after 12 min at 600 MPa. The analysis of the native enzyme exhibited well-defined proportions between α-helix, β-strand, β-turn...

Influence of high pressure and papain treatment on some aspects of beef meat quality

N. Schenková, M. Šikulová, J. Jeleníková, P. Pipek, M. Marek, M. Voldřich

Czech J. Food Sci., 2004, 22(10):S299-S302 | DOI: 10.17221/10686-CJFS  

Influence of post-rigor injection of papain solution and/or high pressure treatment (100, 200, 300 MPa for 10 min) on the quality of beef meat (musculus longissimus lumborum et thoracis) was studied in terms of texture, microbial quality and some physico-chemical parameters (pH, drip loss, water holding capacity). Injection of papain and pressurisation to 100 MPa led to a significant increase of meat tenderness. Application of higher pressures did not lead to further tenderisation. After the 300 MPa pressure treatment the total flora of pressurised compared to untreated samples decreased of 2.5 log cycles.

Inhibition of lactic acid bacteria and bacillus sp. growth in cheese and meat products due to effect of polymer packaging film with incorporated nisin

O. Krejčová, E. Šviráková, J. Dobiáš, M. Plocková

Czech J. Food Sci., 2004, 22(10):S303-S305 | DOI: 10.17221/10687-CJFS  

Active packaging systems based on the application of packaging materials with incorporated and/or immobilized antimicrobial agents provides one of promising trends in food processing. The object of this work was to test the effect of polyethylene (LDPE) packaging film treated with lacquer containing 5% (w/w) Nisaplin^® on the growth of lactic acid bacteria, aerobic sporeforming bacteria, Bacillus cereus and on the changes of total count of bacteria in packaged meat products and processed cheese. Peaces of cheese in contact with nisin treated film were stored at 21°C for 0, 7, and 28 days. The obtained results confirmed significant...

The differences of the structure of triacylglycerols as a result of enzymatic interesterification of fat mixtures with the omega-3 family polyenic fatty acids

S. Ptasznik

Czech J. Food Sci., 2004, 22(10):S306-S309 | DOI: 10.17221/10688-CJFS  

The studies on the enzymatic restructuring process, with the application of interesterification of the fat mixtures, containing fatty acids of omega-3 group (mono-, di-, tri-, tetra-, penta- and hexaenoic) with a differentiated chain length and degree of saturation, were carried out. The investigations were conducted in a model system, in laboratory scale. The Lipozyme® RM IM of Novozymes® A/S company, Denmark, revealing specificity to the sn-1,3 triacylglycerol (TAG), was used as a biocatalyst. The research material consisted of rapeseed oil and fish oil with different levels of EPA and DHA acids. The enzymatic processes of interesterification...

Changes of free fatty acids during ripening of Niva cheese

E. Vítová, J. Zemanová, Š. Bezděková, L. Babák, B. Loupancová, P. Březina

Czech J. Food Sci., 2004, 22(10):S310-S313 | DOI: 10.17221/10689-CJFS  

Changes in the concentrations of free fatty acids in Niva cheese were monitored over the ripening period. Fatty acids were analyzed as methyl esters using gas chromatography with flame ionization detection. Identification has been carried out by comparison of the retention times with those of standard substances. Methanol esterification method using potassium hydroxide catalysis was used for preparing the sample of the fatty acids. The method is simple in respect to instrumentation and chemicals. It can be applied directly to the cheese matrix, which significantly decreases the time for sample preparation. There were total of 30 fatty acids identified...

Monitoring of oligopeptides from blue-veined cheese during ripening

J. Zemanová, E. Vítová, L. Hadra, M. Fišera

Czech J. Food Sci., 2004, 22(10):S314-S316 | DOI: 10.17221/10690-CJFS  

The aim of this study is an isolation of oligopeptides from blue-veined cheese during different stages of ripening and sugests a method which allows their determination, especially electrophoresis. Extraction by water was used to isolate nitrogen compounds and the obtained extract was further fractionated and recleaned. First, high-molecular peptides and proteins were precipitated by methanol, second, the methanol-soluble fraction was further fractionated by gel permeation chromatography. The fractions obtained by this procedures were then analysed using capillary electrophoresis. The obtained results indicate that this procedure, may be applicable...

Nutritional changes of common oat (Avena sativa L.) and naked oat (Avena nuda L.) during germination

D. Gabrovská, V. Fiedlerová, M. Holasová, E. Mašková, J. Ouhrabková, J. Rysová, R. Winterová, A. Michalová

Czech J. Food Sci., 2004, 22(10):S317-S320 | DOI: 10.17221/10691-CJFS  

Changes of basic nutrients (dry matter, ash, proteins, dietary fibre, fat, amino acids), vitamins (B1, B2, niacin, pantothenic acid, B6, C, E and carotenoids), minerals and some trace elements (K, Ca, Mg, P, Zn, Fe, Cu and Mn) during germination of common oat (species Auron) and naked oat (species Abel) were followed. Absorption of water caused decrease of dry matter. Content of protein in dry matter increased due the storage starch decomposition in germinating grains. Methionine was found to be the limiting amino acid. After 8 days of germination the fat content was approximately by 7% and 40% lower and dietary fibre content by 212% and 142% higher...

Changes in potato after different thermal processes

M. Hruškar, M. Krpan, K. Marković, D. Matković, N. Vahčić

Czech J. Food Sci., 2004, 22(10):S321-S324 | DOI: 10.17221/10692-CJFS  

Undesirable thermal processes or storage conditions lead to physical and chemical quality loss of every food. The objective of this study was to determine the total solid content, starch, reducing sugars, nitrates and nitrites in raw and thermal processed red and white potato samples purchased from different geographic origin in Croatia. The potatoes were processed with and without the skin, and cooking processes were carried out in classic way, in the pressure cooker and in the microwave oven. Standard methods of analysis for above-mentioned parameters were used. The results showed no significant influence (P < 0.05) of the geographic...

Determination of free amino acid and biogenic amine contents of hungarian sparkling wines

L. Simon-Sarkadi, E. Szőke, A. Kerekes

Czech J. Food Sci., 2004, 22(10):S287-S289 | DOI: 10.17221/10683-CJFS  

Comparative study was conducted on the basis of free amino acids and biogenic amines of Hungarian sparkling wines originated from 3 producers (Törley, Hungária, Balaton Boglár). Determination of amino acids and biogenic amines was accomplished by ion-exchange chromatography using an amino acid analyser. The dominant free amino acids in sparkling wines were proline and arginine and the major biogenic amine was spermidine. Based on results of chemometric analyses, free amino acid and biogenic amine contents seemed to be closely related to quality and the technology of sparkling wine making.

Changes of acrylamide levels in food products during technological processing

L. Dunovská, J. Hajšlová, T. Čajka, K. Holadová, K. Hájková

Czech J. Food Sci., 2004, 22(10):S283-S286 | DOI: 10.17221/10682-CJFS  

Acrylamide represents toxic compound presence of which in heat processed foodstuffs has been proven only recently. This chemical is of a great health concern since it is classified as a human carcinogen by the International Agency for Research on Cancer (IARC). Relatively high amounts of acrylamide have been found mainly in starch rich foods such as potato chips, French fries, roast potatoes, breakfast cereals and crisp bread. Concentrations of this hazardous substance in certain food products may reach up to several mg/kg, depending on the type of raw commodity and the way of its processing. Changes of acrylamide levels in potato chips during frying...

Influence of dough ingredients on 3-Mcpd formation in toast

C. M Breitling-Utzmann, H. Hrenn, N. U Haase, G. M Unbehend

Czech J. Food Sci., 2004, 22(10):S25-S28 | DOI: 10.17221/10605-CJFS  

The influences of both traditional dough ingredients like fat and salt and a commercially used baking agent on the formation of 3-chloropropane-1,2-diol (3-MCPD) during toasting of bread were investigated. Whereas varying the fat or salt contents within technologically practicable limits showed negligible effects on 3-MCPD formation, the baking agent turned out to have a crucial impact on generating 3-MCPD in toasted bread slices. We found considerable evidence that the baking agent's main component saccharose was the major cause for its boosting the 3-MCPD formation. Emulsifiers like mono- and diacylglycerols or lecithin did not have any significant...

Dietary fibres from Brassica vegetables bind heterocyclic amines in vitro (abstract only)

K. Skog, R. Maul, M. Nyman

Czech J. Food Sci., 2004, 22(10):S250

An association between the intake of heterocyclic amines (HAs) and development of cancer have been observed in epidemiological studies, while in other studies no such correlation has been found. HAs are mutagenic/carcinogenic compounds formed at low levels via the Maillard reaction during cooking of animal tissue. Animal studies have shown that dietary fibre (wheat bran, sorghum and pectin) may reduce the amount of HAs, for example IQ and MeIQx, that can be absorbed from the diet. This might have significance for tumour initiation, since the concentration of carcinogens in the bloodstream determines the initiating event. A diet high in dietary fibre...

Comparison of two methods for acrylamide determination and dietary intake of acrylamide from potato crisps in Slovakia

Z. Ciesarová, V. Balasová, E. Kiss, E. Kolek, P. Šimko, M. Kováč

Czech J. Food Sci., 2004, 22(10):S251-S254 | DOI: 10.17221/10674-CJFS  

Two GC/MS methods for acrylamide determination in potato crisps were used. By the method without derivatisation the presence of acrylamide was confirmed. The quantities of acrylamide were compared by the bromination method with ¹³C₃-acrylamide and D₃-acrylamide as internal standards. A suitable agreement between the results obtained from two independent laboratories was achieved; the difference was less than 5%. Using average level of acrylamide in crisps 986.5 μg/kg and mean consumption data on potato crisps in Slovakia it was calculated that consumers are exposed to 8.5 μg acrylamide daily from its which means...

Chloropropanols and their esters in cereal products

C. G Hamlet, P. A Sadd

Czech J. Food Sci., 2004, 22(10):S255-S258 | DOI: 10.17221/10676-CJFS  

Chloropropanols, in particular monochloropropanediols (MCPDs) are food contaminants that can form in the high temperature crust region of cereal products. Previous studies have indicated that MCPD-esters may be formed from a reaction between chloride ions and some lipids, although, to date, these compounds have not been reported in cereal products. MCPD-esters were extracted into an organic solvent and cleaned up by a preparative thin-layer chromatography procedure. Sample extracts were analysed using gas chromatography/mass spectrometry (GC/MS) and the data compared with that obtained from a reference MCPD-ester, prepared by a custom synthesis. A...

Effects of yeast stress and organic acids on chloropropanols formation in cereal products

C. G Hamlet, P. A Sadd

Czech J. Food Sci., 2004, 22(10):S259-S262 | DOI: 10.17221/10675-CJFS  

A major precursor of monochloropropanediols (MCPDs) in leavened cereal products is glycerol, which is formed as a natural by-product of yeast fermentation. However, yeast metabolism is affected by stresses such as low osmotic pressure from e.g. the incorporation of sugar or salt in the dough recipe. Tests with cooked model doughs have shown that glycerol production was proportional to yeast level and limited by available sugars, but high levels of yeast inhibited MCPD formation. Added glucose did not increase the production of glycerol but did promote the generation of MCPDs. This effect was attributed to the thermal generation of organic acids from...

Formation and decomposition of 3-chloropropane-1,2-diol in model systems

M. Doležal, P. Calta, J. Velíšek

Czech J. Food Sci., 2004, 22(10):S263-S266 | DOI: 10.17221/10677-CJFS  

Model experiments were carried out using mixtures of 3-chloropropane-1,2-diol (3-MCPD), its precursor glycerol, NaCl, water and an emulsifier. The aim of this study was to simulate formation and decomposition of 3-MCPD at the surface layers of thermally processed foods containing naturally present or intentionally added salt. The formed 3-MCPD levels depend on temperature and reach the maximum value at 230°C. One kg of glycerol gives rise to about 50 mg of 3-MCPD, while about 0.6 mg of 3-MCPD arise at 100°C. The rate constants k₁ of 3-MCPD formation from glycerol and constants k₂ of 3-MCPD decomposition were calculated employing...

Survey of 3-chloropropane-1,2-diol and its precursors in foods in the Czech Republic

V. Divinová, B. Svejkovská, O. Novotný, J. Velíšek

Czech J. Food Sci., 2004, 22(10):S267-S271 | DOI: 10.17221/10678-CJFS  

A survey of the levels of 3-chloropropane-1,2-diol (3-MCPD) and its precursors in a range of selected retail food products in the Czech Republic is reported. The foods were selected according to their content of water, chlorides and lipids and included foods processed at high temperatures and/or stored for a long time. The content of 3-MCPD was determined by the GC/MS method using deuterium-labeled 3-MCPD. Water content and pH value of the analysed foods were determined together with the recognised precursors of 3-MCPD, fat, glycerol and chlorides. An insight into the level of 3-MCPD influenced by these variables has been done by principal components...

Investigation of bisphenol a diglycidyl ether, bisphenol f diglycidyl ether and their hydroxy and chlorohydroxy derivatives stability in water-based food simulants

I. Poustková, J. Dobiáš, J. Poustka, M. Voldřich

Czech J. Food Sci., 2004, 22(10):S272-S275 | DOI: 10.17221/10679-CJFS  

Varnishes used as the inner coatings of food cans are often based on epoxy resins or vinylic organosols. The epoxy resins can be produced from bisphenol A (BPA) and bisphenol F (BPF) and they also contain bisphenol A diglycidyl ether (BADGE) of bisphenol F diglycidyl ether (BFDGE) as stabilising components. These compounds may break down during storage and also by influence of food simulants. The stability of BADGE and BFDGE was studied using reverse-phase gradient high performance liquid chromatography (RP-HPLC) with fluorescence detection (FLD). Four experiments were compared: (i) BPA solution at the concentration 3 μg/ml of each food simulant,...

Characterisation of physicochemical interactions between benzo(a)pyrene contained in vegetable oil and polyethylene terephtalate

B. Skláršová, P. Šimko, P. Šimon, E. Belajová

Czech J. Food Sci., 2004, 22(10):S276-S279 | DOI: 10.17221/10680-CJFS  

Rapeseed oil was spiked with benzo(a)pyrene [BaP] solution at the level of 29.4 μg/kg, filled into polyethylene terephtalate [PET] cylindrical shape receptacles and the BaP concentrations were followed for during 97 h by HPLC. During this time, the BaP concentrations decreased to 22.9 μg/kg due to an interaction of BaP with PET. Using a modified kinetic equation, the diffusion coefficient for BaP in the oil was determined. Calculation of the area occupied by a BaP molecule on PET surface suggests that either the multilayer adsorption or the diffusion of BaP into PET bulk came into account as the decisive factors bringing about the decrease of...

The determination of N-methylcarbamate pesticides using enzyme immunoassays with chemiluminescent detection

B. Mičková, P. Rauch, A. Montoya, E. Ferri, F. Fini, S. Girotti

Czech J. Food Sci., 2004, 22(10):S280-S282 | DOI: 10.17221/10681-CJFS  

In the present work, enzyme-linked immunosorbent assays (ELISAs) with chemiluminescent detection for the determination of carbofuran, carbaryl and methiocarb were developed and the analytical parameters of these assays were compared with those of ELISAs with colorimetric detection. The sensitivity of immunochemical methods was expressed as detection limit, linear working range, and I₅₀ value. In comparison with colorimetric ELISA, the ability of the chemiluminescent reagents to detect lower concentrations of HRP allowed to decrease the optimal antibody and conjugate concentrations and to reach better analytical parameters. The experimental...

Enzymatic changes in minimally processed apples

J. Schovánková, E. Cocci, H. Opatová, M. Dallarosa

Czech J. Food Sci., 2004, 22(10):S325-S328 | DOI: 10.17221/10693-CJFS  

The impacts of chemical treatment and modified atmosphere on enzymatic changes in minimally processed apples were evaluated. Slices of apple cultivars Golden Delicious and Red Delicious were packed in plastic bags with modified atmospheres: 85% N₂, 5% O₂, 10% CO₂ (MA) and 78% N₂, 21% O₂, 1% other gases (NA). The changes in colour, firmness, polyphenoloxidase activity, total phenols content and concentration of single phenols during storage were measured. It has been found that the effects of storage atmosphere and antioxidant treatment were not as important as the choice of apple cultivar. Red...

Application of NIR analysis to verify cocoa powder authenticity

A. Trilčová, J. Čopíková, M. A Coimbra, A. Barros, L. Egert, A. Synytsya, H. Křístková

Czech J. Food Sci., 2004, 22(10):S329-S332 | DOI: 10.17221/10694-CJFS  

At the present time the use of reliable control methods to ensure the labeled quality of food is task for organizations that have to limit or eliminate the falsification. The presentation describes the results of common analytical methods, NIR spectrometry and FT-IR spectrometry applied to cocoa powder. The two spectrometric techniques are statistically processed that allows discrimination of authentic and fraudulent cocoa powder samples.

New formulations for low-fat frankfurters and its effect on product quality

M. A LURUEÑA-MARTÍNEZ, I. Revilla, A. M Vivar-Quintana

Czech J. Food Sci., 2004, 22(10):S333-S337 | DOI: 10.17221/10695-CJFS  

The effects of reducing fat level (9% and 12%), substituting pork fat with olive oil and adding locust bean/xanthan gum on emulsion stability, jelly and fat separation, cook loss, and hardness of frankfurters were investigated and compared with control sample elaborated with 20% of fat content. Results showed that addition of locust bean/xanthan gum produced a significant increase in hydration/binding properties, characterised by lower cook losses, increasing yield, better emulsion stability and lower jelly and fat separation. The substitution of fat pork by olive oil did not affect these parameters. Multivariate comparison between elaborated low-fat...

Antioxidation capacity of Maillard systems with carbonyl products of sugar fragmentation

K. Cejpek, L. Jarolímová, J. Velíšek

Czech J. Food Sci., 2004, 22(10):S60-S63 | DOI: 10.17221/10612-CJFS  

A role of reactive C₂-C₅ α-dicarbonyl and α-hydroxycarbonyl products of sugar fragmentation in the development of antioxidative activity (AOA) was investigated after heating in 0.5M binary aqueous mixtures with amino acids. Several kinetic and activity parameters related to the development of reducing power in the systems with different carbonyl fragments as well as glucose were evaluated and compared. The formation of electrochemically active compounds was correlated with colour development. To assess the antioxidation effects more properly, several different methods were used for AOA evaluation of the systems tested...

Phenolic compounds as cross-links of plant derived polysaccharides

M. Bunzel, J. Ralph, H. Steinhart

Czech J. Food Sci., 2004, 22(10):S64-S67 | DOI: 10.17221/10613-CJFS  

Plant cell wall polysaccharides are partially cross-linked via phenolic compounds. As shown in the past, the most important phenolic compounds to cross-link plant cell-wall polysaccharides are ester-linked ferulic acid dimers, but p-coumarate dimers were also shown to be potential cross-linking compounds. Recently, ferulic acid dimers were identified and quantified in a range of cereal grains. The isolation of 8-O-4-dehydrodiferulic aciddiarabinoside from maize bran shows that diferulic acids are able to form intermolecular cross-links between arabinoxylans. The more recently identified sinapic acid dehydrodimers and ferulic acid dehydrotrimers...

Fluorescence fingerprints as a rapid predictor of the nutritional quality of processed and stored foods

I. Birlouez-Aragon, P. A Mas, L. Ait Ameur, N. Locquet, E. De St Louvent, M. Zude

Czech J. Food Sci., 2004, 22(10):S68-S71 | DOI: 10.17221/10614-CJFS  

Foods are complex mixtures of macro- and micronutrients, which interact leading to oxidation, glycation and hydrolysis upon heating (sterilization, cooking) and storage. The nutritional quality and safety is consequently affected justifying the need for accurate monitoring of the evolution of the food composition during processing and in product shelf life. Classical chromatographic analysis as well as newly proposed rapid methods based on fluorescence spectrometry analyses are applied in the present study on (i) fresh and stored carrots, (ii) infant formula resembling model, (iii) heated rapeseed oil, and (iv) wheat biscuits. Fluorescence fingerprints...

Synthesis of (Z,Z)-octadeca-10,12-dienoic acid

C. Kellersmann, W. Francke, H. Steinhart

Czech J. Food Sci., 2004, 22(10):S73-S75 | DOI: 10.17221/10615-CJFS  

(Z,Z)-Octadeca-10,12-dienoic acid was synthesised by coupling (Z)-1-bromohept-1-ene with protected undec-10-yne-1-ol. Stereoselective hydrogenation of the triple bond of the obtained enyne-system followed by deprotection yielded (Z,ZZ)-octadeca-10,12-dienol. The latter can be easily oxidized to the corresponding acid.

Fat blends on the base of structural triglycerides

V. Filip, M. Zárubová, I. Piska, J. Šmidrkal

Czech J. Food Sci., 2004, 22(10):S76-S79 | DOI: 10.17221/10616-CJFS  

Fat blends for manufacture of trans isomer-free emulsified fats are prepared by blending of 20-30% of structured fat with vegetable oil. Structured fats on the base of trisaturated triglycerides are produced by basic or enzymatic catalyzed transesterification of fully hydrogenated coconut oil with fully hydrogenated palmstearine or low erucic rapeseed oil. Physical properties of transesterificated structured fats produced by enzymatic reaction using immobilized sn-1,3 specific lipase Lipozyme TL IM or by randomization are similar. The replacement of palmitic acid with stearic acid without any changes in the ratio between medium chain FA and...

Functionality changes of natural antioxidants during food processing and storage

J. Pokorný, Š. Schmidt, H. T. T. Nguyen

Czech J. Food Sci., 2004, 22(10):S80-S83 | DOI: 10.17221/10617-CJFS  

Food raw materials and products contain inhibitors of oxidation reactions, both in the lipidic phase and the aqueous phase. The most important inhibitors are phenolic antioxidants. During food processing and storage, concentrations of antioxidants in the two phases reach an equilibrium. Phenolics react with lipidic free radicals, being converted into antioxidant free radicals, quinones, polymers and copolymers. Some degradation products possess an antioxidant activity, too. The relative antioxidant activity decreases with decreasing concentration of oxygen in the system and with increasing temperature. Antioxidants are more rapidly decomposed in surface...

Chemical and technological characterisation of melanoidins from espresso coffee (abstract only)

F. Bacchini, A. Dagostina, G. Boschin, A. Arnoldi

Czech J. Food Sci., 2004, 22(10):S89

Abstract: Espresso coffee is becoming more and more fashionable because it offers a great sensory satisfaction. The flavour, the taste and the opaque foam on the top are the fundamental properties for defining the acceptability and quality of an espresso cup. Roasting is extremely important in the development of these features: during this process green coffee beans of these features: during this process green coffee beans.

Heat-induced degradation of inulin

A. Böhm, I. Kaiser, A. Trebstein, T. Henle

Czech J. Food Sci., 2004, 22(10):S90-S92 | DOI: 10.17221/10623-CJFS  

Abstract: Heat treatment of inulin at 135 to 190°C leads to a decrease in the measurable amount of the fructan, when quantified as fructose after enzymatic hydrolysis. Using high-performance anion-exchange chromatography with pulsed amperometric detection, degradation of the fructan chains and concomitant formation of low-molecular products was observed, most likely representing di-D-fructose dianhydrides. Heat-induced degradation of inulin during thermal processing of foods like bakery products must be taken into account within the discussion about possible prebiotic properties of the fructan.

A new pathway of lactose degradation and arginine derivatization in milk

E. Mavric, T. Henle

Czech J. Food Sci., 2004, 22(10):S93-S95 | DOI: 10.17221/10624-CJFS  

Abstract: Recently, N-δ-[5-(3-hydroxypropyl)-4-oxo-imidazolon-2-yl]-􀑙-ornithine (PIO) was identified as a new arginine derivative, formed exclusively from the side-chain of peptide-bound arginine and degradation products of oligosaccharides with 1,4-glycosidic linkages, thus probably representing the major form of arginine derivatization in heated milk products. The formation mechanism of PIO was clarified via identification of a previously unknown C5 dicarbonyl precursor, namely 3,4-dideoxypentosulose (3,4-DDPs). 3,4-DDPs was isolated as the corresponding chinoxaline from reaction mixtures containing N-α-hippuryl arginine, lactose...

Dietary intake and urinary excretion of Maillard reaction products (MRPs)

A. Förster, Y. Kühne, T. Henle

Czech J. Food Sci., 2004, 22(10):S96-S98 | DOI: 10.17221/10625-CJFS  

The aim of our study was to investigate the influence of nutrition on the urinary excretion of Amadori products, pyrraline and pentosidine in a dietary study involving 18 healthy volunteers. Starting with day two, participants had to avoid Maillard product containing food for a period of 7 days, followed by day nine without dietary restrictions. Samples of 24 h-urine were collected and analysed for free furosine, pyrraline and pentosidine using dedicated chromatographic methods. For all MRPs, a significant decrease in the amount excreted with urine was observed due to the MRP-free diet. Urinary excretion of free pyrraline and fructoselysine, which...

S-Substituted cysteine derivatives in production of flavour and colour

J. Velíšek, R. Kubec

Czech J. Food Sci., 2004, 22(10):S54-S59 | DOI: 10.17221/10611-CJFS  

A brief review of our continuous investigations on S-substituted cysteine derivatives is presented herein. It comprises a summary on nonenzymatic (thermal) decomposition of these amino acids as well as on their role in the formation of blue and pink pigments during processing of garlic and onion, respectively. The emphasis is put on four most common derivatives, namely S-methyl-, S-allyl-, S-1-propenyl- and S-propylcysteine sulfoxides (methiin, alliin, isoalliin and propiin, respectively). Our results demonstrate that these sulfur-containing amino acids are the key primary precursors in the formation of both flavour...

Flavour and vinylogous compounds generated by Maillard-type reactions

I. Blank, T. Davidek, Ph. Pollien, S. Devaud

Czech J. Food Sci., 2004, 22(10):S50-S53 | DOI: 10.17221/10610-CJFS  

The sources of reducing sugars and free asparagine of two different cracker products were identified, and acrylamide formation during baking was measured. The application of an asparaginase decreased the acrylamide content by at least 70% in both products. Replacing ammonium hydrogencarbonate by sodium hydrogencarbonate as baking agent and replacing reducing sugars by sucrose resulted in almost 80% less acrylamide in the wheat cracker. Decreasing free asparagine and reducing sugars in the ingredients and a lower end-temperature during baking lowered the acrylamide content of the potato cracker by about 50%.

FFA Evolution during storage of ground roasted coffee

M. Vila, M. P DEPEÑA, C. Cid

Czech J. Food Sci., 2004, 22(10):S338-S341 | DOI: 10.17221/10696-CJFS  

Coffee acylglycerols hydrolysis and free fatty acids (FFA) oxidation reactions produce a FFA evolution that can affect to coffee quality during storage. The aim of this work was to study and to compare the FFA evolution of two ground roasted coffee samples: Brazilian Arabica 100% (A100) and Brazilian Arabica-India Cherry Robusta blend (A80:R20). Coffees were packaged under vacuum and stored at 25°C during 180 days. A significantly higher FFA initial concentration in A80:R20 coffee was observed. However, at 180 days, a higher increase of FFA concentration was shown in A100 sample. In conclusion, FFA oxidation seemed to be faster in A80:R20 blend than in A100.

Effect of gamma-irradiation on microbial decontamination and organoleptic quality of black pepper (Piper nigrum L.)

J. Sádecká, E. Kolek, Z. Salková, J. Petríková, M. Kováč

Czech J. Food Sci., 2004, 22(10):S342-S345 | DOI: 10.17221/10697-CJFS  

The influence of ionizing radiation treatment with different doses (5 kGy, 10 kGy and 30 kGy) of γ-rays on the microbial decontamination of powdered black pepper was investigated. It was found out that a dose of 5 kGy is sufficient to achieve a total viable count of microbial contamination. Subsequently the effect of γ-irradiation dose on the possible changes in composition of the black pepper essential oil and simultaneous potential alterations in its organoleptic quality (flavour) were studied. No significant changes in the volatile oil compounds content were observed with the radiation doses of 5 kGy and 10 kGy. Ionizing dose of 30 kGy...

Effect of some refining steps on rapeseed oil triacylglycerol structures

Š. Schmidt, M. Vajdák, S. Sekretár, V. Koman

Czech J. Food Sci., 2004, 22(10):S346-S348 | DOI: 10.17221/10698-CJFS  

Determination of fatty acids at sn-2 position in rapeeed oil triacylglycerols with low content of erucic acid is desribed. Oleic acid constitues of 48% of the fatty acids, linoleic acid 37.8%, linolenic acid 13.5%, and small amounts of the usual saturated acids make up the remainder. The effect of industrial alkali refining (degumming and neutralization), bleaching, deodorization and interesterification was studied. The use of different refining steps did not cause any or only mild triacylglycerol structure modification, other than interesterification, obviously.

Evaluation of ketchup authenticity - chemical changes of markers during production and distribution

V. Soukupová, H. Čížková, M. Voldřich

Czech J. Food Sci., 2004, 22(10):S349-S352 | DOI: 10.17221/10699-CJFS  

The set of 12 samples of ketchups with the known NTSS content varying from 4 to 12% was analyzed, the NTSS content was correlated with the content of individual chemical markers (lycopene, β-carotene, pyrrolid-5-one-2-carboxylic acid (PCA, pyroglutamic acid), glucose, fructose, sucrose, citric and malic acid, Na⁺, K⁺, Ca²⁺, Mg²⁺, formol number). The effect of processing and storage conditions to the PCA and lycopene content was followed. NTSS correlates well with K⁺, Mg²⁺, PCA, formol number, malic and citric acid content, no correlation was found for carotenoids content. PCA content,...

LAST MINUTE: Formation of semicarbazide (SEM) from natural compounds in food by heat treatment

R. Gatermann, K. Hoenicke, M. Mandix

Czech J. Food Sci., 2004, 22(10):S353-S354 | DOI: 10.17221/10700-CJFS  

LAST MINUTE: Stability of acrylamide in food during storage

K. Hoenicke, R. Gatermann

Czech J. Food Sci., 2004, 22(10):S355-S356 | DOI: 10.17221/10701-CJFS  

Analysis of furan in different foodstuffs using gas chromatography mass spectrometry

K. Hoenicke, H. Fritz, R. Gatermann, S. Weidemann

Czech J. Food Sci., 2004, 22(10):S357-S358 | DOI: 10.17221/10702-CJFS  

Decrease of the allergenic activity of foods by shock waves

N. Wolff, U. Cogan, H. Zuckerman, N. Karin, Y. Levy, Y. E Krasik, J. Felsteiner, R. Reifen, S. Yannai

Czech J. Food Sci., 2004, 22(10):S36-S39 | DOI: 10.17221/10607-CJFS  

Food allergy significantly affects the life-quality for many people worldwide and is life-threatening in extreme cases. In recent years the incidence of this disease shows a gradual increase in many countries. It is a well-established fact that common food-processing operations involving heat treatments fail to significantly decrease the allergenic reactivity of foods. Furthermore, allergenic proteins are remarkably resistant to proteolysis by digestive enzymes and often remain intact after passing through the gastrointestinal tract. The tested materials were protein extracts from sesame seeds, milk and peanuts, or isolated proteins from the same sources....

The changes of α-galactosides during germination and high pressure treatment of chick-pea seeds

J. Dostálová, P. Kadlec, J. Culková, A. Hinková, M. Houška, J. Strohlam

Czech J. Food Sci., 2004, 22(10):S41-S44 | DOI: 10.17221/10608-CJFS  

The α-galactosides negatively affect of digestibility of grain legumes. The most effective way of α-galactosides decreasing is germination. The content of α-galactosides in chick-pea was decreased by 4 days germination up to 24% of original value in dry seeds. The 2 days germinated chick-pea seeds were treated by pressure 500 MPa for 10 minutes. The α-galactosides content was decreased by this treatment up to 31% of value before pressurisation and during 21 days storing decreased up to 7% of value before pressurisation.

Acylglycosides as future food preservatives

J. Prekop, R. Červenková, E. Bartošová, Z. Špičková, J. Šmidrkal, V. Filip, M. Plocková

Czech J. Food Sci., 2004, 22(10):S45-S48 | DOI: 10.17221/10609-CJFS  

In this work monoesters of sucrose and 􀑑-glucose with fatty acids (both even and odd) were prepared as pure substances using the direct selective esterification of free sugar with bulky acylating agent. This compounds were examined for their antibacterial activity (against Gram-positive bacteria) and antifungal activity.

Hydroxymethylfurfural: an indicative parameter of heat damage in cereal products

L. Ait Ameur, M. Zude, G. Trystram, I. Birlouez-Aragon

Czech J. Food Sci., 2004, 22(10):S99-S101 | DOI: 10.17221/10626-CJFS  

The main chemical changes occurring during biscuit cooking result from two complex reactions involving reducing sugars: the Maillard reaction and caramelisation, both of them being responsible for non enzymatic browning. These reactions were assessed by determinations of furosine (Fu), hydroxymethylfurfural (HMF), and colour at different times (each 2 min) of the cooking process (10 min). The surface colour of biscuits was carried out with L* a* b* parameters, and the global browning development was measured by the reflectance of the whole biscuit in powder. Simultaneous formation of HMF, Fu and browning were investigated...

Enzyme-linked immunosorbent assay for general and specific detection of Listeria spp. and monocytogenes in dairy products

M. Blažková, L. Karamonová, P. Rauch, G. M Wyatt

Czech J. Food Sci., 2004, 22(10):S242-S245 | DOI: 10.17221/10671-CJFS  

Bacteria of the genus Listeria are widely distributed in the environment and they frequently contaminate food. Among all species in the genus Listeria, only L. monocytogenes has been implicated in serious human illness. The other Listeria spp. are considered to be avirulent to man but they may cause a variety of disease symptoms or even death in animal. These bacteria are well equipped to survive food processing technologies. For example, they tolerate high concentrations of salt and relatively low pHs, and worst of all, they are able to multiply at refrigeration temperatures. This makes Listeria microorganisms a serious...

Conference "Chemical Reactions in Foods V", Sept 29-Oct 1, 2004, Prague, Czech RepublicContent

editors

Czech J. Food Sci., 2004, 22(10):I-VIII  

Comparison of oxidative resistance of traditional and high-oleic peanut oils in emulsions

A. Zainuddin, J. Parkányiová, L. Parkányiová, J. Pokorný, H. Sakurai

Czech J. Food Sci., 2004, 22(10):S136-S139 | DOI: 10.17221/10637-CJFS  

The oxidation rate of vegetable oils strongly depends on the content of polyunsaturated fatty acids, natural antioxidants and prooxidants. The resistance of oil against oxidation thus depends very much on the linoleic acid content. Virginia peanut oil (a traditional cultivar, containing 30% linoleic acid) was compared with SunOleic peanut cultivar (containing only 3% linoleic acid). The tocopherol content was rather similar in the two oil samples. Emulsions were prepared using soybean lecithin as an emulsifying agent. The formation of conjugated hydroperoxides was measured at 234 nm. The induction period differred very much in bulk oil, but only moderately...

Lipid oxidation in margarine emulsions

I. Pokorná, V. Filip, J. Šmidrkal

Czech J. Food Sci., 2004, 22(10):S140-S143 | DOI: 10.17221/10638-CJFS  

Influence of different storage atmosphere (argon and oxygen atmosphere) and influence of monoacylglycerol's emulsifier (with the carbon chain containing 10, 12, 14, 16, 18 carbon atoms and commercial emulsifier D and a model mixture of monoacylglycerols with the carbon chains containing 10, 12, 14 carbon atoms) on lipid oxidation in margarine emulsions were observed. The rate of lipid oxidation in emulsion with oxygen atmosphere depends on oxygen diffusion through the emulsion layer, while lipid oxidation in emulsion with inert atmosphere is influenced by initial oxygen concentration in water and fat phase. Lipid oxidation in emulsion also depends...

Determination of stigmasterol hydroperoxides using high-performance liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization

S. Kemmo, V. Ollilainen, A.-M. Lampi, V. Piironen

Czech J. Food Sci., 2004, 22(10):S144-S146 | DOI: 10.17221/10639-CJFS  

A new specific method using high-performance liquid chromatography-mass spectrometry (HPLC-MS) for the detection of stigmasterol hydroperoxides was developed. Hydroperoxides of stigmasterol were obtained by photo-oxidation (90 min) in the presence of methylene blue as a sensitizer. The separation was performed using normal-phase chromatographic conditions. The MS detection was carried out with an ion-trap mass spectrometer using atmospheric pressure chemical ionization (APCI) and positive ion mode. Stigmasterol hydroperoxides were seen to produce no protonated molecular ions [M + H]⁺ but instead fragments representing loss of one or two...

Fluorescence spectroscopy for monitoring extra virgin olive oil deterioration upon heating

R. Cheikhousman, M. Zude, D. J.-R. Bouveresse, D. N Rutledge, I. Birlouez-Aragon

Czech J. Food Sci., 2004, 22(10):S147-S150 | DOI: 10.17221/10640-CJFS  

Fluorescence spectroscopy is a reliable and fast method for determining the deterioration of extra virgin olive oil (EVOO). EVOO was analysed by HPLC for determining antioxidant changes in EVOO due to heating at 170°C for 3 h. This thermal oxidation caused a significant exponential decrease in hydroxytyrosol (OH-Tyr) and vitamin E (vitE), while the reduction in the tyrosol content was relatively small. Hydroperoxydes were analysed by an indirect colorimetric method. Their content decreased exponentially during the heating process. Fluorescence excitation spectra with emission wavelength at 330 nm were recorded to monitor the evolution of polyphenols...

Acrylamide formation during frying of potatoes: thorough investigation on the influence of crop and process variables

T. De Wilde, B. De Meulenaer, F. Mestdagh, R. Verhé, Y. Govaert, S. Fraselle, J. M Degroodt, S. Vandeburie, K. Demeulemeester, A. Calus, W. Ooghe, C. Van Peteghem

Czech J. Food Sci., 2004, 22(10):S15-S18 | DOI: 10.17221/10602-CJFS  

Acrylamide, which is a suspected human carcinogen, is particularly formed in starch-rich foodstuffs, like potato. The inter- and intraspecies variability of the potato causes a dispersion in the amount of acrylamide. This intraspecies variability can be influenced through agricultural practices and storage conditions. By assessing these factors, advice to potato producers can be given in order to lower the formation of acrylamide during frying.

Optimisation of a headspace solid phase mi croextraction (HS-Spme) method to determine hexanal in baby foods

G. García-Llatas, M. J. Lagarda, R. Farré, P. Abellán, F. Romero

Czech J. Food Sci., 2004, 22(10):S151 | DOI: 10.17221/10642-CJFS  

Fluorescence of oxidizing oil-in-water emulsions (abstract only)

V. Rampon, A. VILLIÈRE, D. J McClements, C. Genot

Czech J. Food Sci., 2004, 22(10):S153

Front-face fluorescence spectroscopy was used to characterize modifications of fluorescence spectra of oil-in-water emulsions, stabilized by bovine serum albumin (BSA) or sodium caseinate during aging at 50°C. Commercial sunflower oil or the same oil stripped of tocopherols, were used as the apolar phase of the emulsions. The 3D-fluorescence spectra of the emulsions were characterized by three groups of fluorescent pigments: (i) protein aromatic amino acid residues, mainly tryptophanyl residues (Trp); (ii) pigments initially present in the oils:tocopherol and others; (iii) new fluorescent pigments due to reactions of lipid oxidation products with the...

Structural and chemical modifications of β-lactoglobulin induced by aldehydes (abstract only)

L. Li Yuet Hee, M. Dalgalarondo, H. Rogniaux, M. Viau, C. Genot

Czech J. Food Sci., 2004, 22(10):S154

Aldehydes are odour-active compounds issued from reactions such as lipid oxidation. They react with other food constituents such as proteins, that decreases their availability as aroma compounds, but also induces alterations of the proteins. This study was aimed to evidence the structural and chemical modifications of β-lactoglobulin in the presence of aldehydes varying in their unsaturation. β-Lactoglobulin solutions (1 g/l; 20mM phosphate buffer, pH 6.8; 80mM NaCl) were stored at 40°C in the presence of hexanal, 2-hexenal or 2,4-hexadienal (aldehyde/protein molar ration = 25) for 3 days. Whatever the aldehyde, formation of more hydrophobic,...

Antioxidant activity of acerola extracts

I. Nagamine, H. Sakurai, H. T. T. Nguyen, M. Miyahara, J. Parkányiová, Z. Réblová, J. Pokorný

Czech J. Food Sci., 2004, 22(10):S155-S158 | DOI: 10.17221/10645-CJFS  

West Indian cherries or acerola fruits (Malpighia glabra L.) are very rich in ascorbic acid, and also contain flavonoids and anthocyanins. Therefore, their antioxidant activity is interesting. Aqueous and methanolic acerola extracts increased the stability of β-carotene-linoleic acid emulsions against oxidation. Flavonoids and anthocyanins obviously enhanced the effect of ascorbic acid. The effect of natural acerola antioxidants was comparable to that of phenolic antioxidants, such as ferulic acid. During the determination of antioxidant activity in emulsions, carotene was destroyed following a complex kinetics in the beginning of oxidation, but...

Hepatoprotective Effects of acerola cherry extract powder against d-galactosamine-induced liver injury in rats and its bioactive compounds

I. Nagamine, M. Fujita, I. Hongo, H. T. T. Nguyen, M. Miyahara, J. Parkányiová, J. Pokorný, J. Dostálová, H. Sakurai

Czech J. Food Sci., 2004, 22(10):S159-S162 | DOI: 10.17221/10647-CJFS  

Treatment with the water and tropical lemon juice extract powders from acerola fruit purees and leaves (100 mg/kg) significantly ameliorates the hepatic inflammatory responses such as increased serum levels of AST, ALT, and GGT in rats subjected to acute D-galactosamine (GalN) intoxication. The protective effects of their constituents could be related to their antioxidant activities to neutralise free radicals to attenuate hepatic lipid peroxidation and thus can protect liver damage. The effect of the water extract powder from fruit purees (100 mg/kg) was moderately stronger than that of ascorbic acid (10 mg/kg), but weaker than that of cyanidin-3-O-rhamnoglucoside...

Protein-lipid interactions during oxidation of liposomes

H. Salminen, R. Kivikari, M. Heinonen

Czech J. Food Sci., 2004, 22(10):S133-S135 | DOI: 10.17221/10636-CJFS  

Oxidation of bovine serum albumin and its interaction with phenolic red raspberry and bilberry extracts (4.2 and 8.4 μg/ml) was investigated in a liposome system. Samples were incubated in the dark at 37°C with copper, and the extent of oxidation was measured by determing the loss of tryptophan fluorescence and the formation of protein carbonyls, conjugated diene hydroperoxides and hexanal. Both red raspberry and bilberry extracts inhibited lipid and protein oxidation. Red raspberry extract in 4.2 μg/ml concentration was the best inhibitor against both lipid and protein oxidation. In conclusion, oxidative deterioration due to protein-lipid oxidation...

Prostaglandin E₂-dependent activation of Src-Stat3 signal pathway in human lung adenocarcinoma cells

I. Nagamine, T. Yano, K. Endoh, T. Yamaki, T. Morimura, M. Miyahara, H. T. T. Nguyen, J. Pokorný, H. Sakurai

Czech J. Food Sci., 2004, 22(10):S130-S132 | DOI: 10.17221/10635-CJFS  

Accumulating evidence suggests that overproduction of prostaglandin (PG) E2 attributable to induction of cyclooxygenase-2 plays an important role in the development of lung adenocarcinoma. Recently, we have reported that a PGE2 receptor, EP3 is involved in appearance of malignant phenotype of a lung adenocarcinoma cell (A549 cell). In line with our previous study, here we investigated if Src signaling could be involved in PGE2-stimulated growth of A549 cells via EP3. PGE2-dependent cell growth in A549 cell positively related to the activation of Src. A specific antagonist against EP3 abrogated the cell growth and Src activation in the cells stimulated...

Thermal processing contaminants in foodstuffs and potential strategies of control

A. Studer, I. Blank, R. H Stadler

Czech J. Food Sci., 2004, 22(10):S1-S10 | DOI: 10.17221/10600-CJFS  

Over the past decades, researchers from academia, industry, and National authorities and enforcement laboratories, have gained increasing insight in understanding the presence, formation and potential risk to public health posed by the compounds formed during the domestic cooking and heat-processing of different foods. Compounds already intensively studied are the heterocyclic aromatic amines, polycyclic aromatic hydrocarbons, and chloropropanols. Concrete measures have been introduced by the food industry to control certain contaminants, exemplified by the introduction of enzymatic hydrolysis of plant proteins or over-neutralization to reduce concentrations...

Factors affecting the formation of reducing compounds from biacetyl

L. Jarolímová, J. Rysová, K. Cejpek, J. Velíšek

Czech J. Food Sci., 2004, 22(10):S102-S105 | DOI: 10.17221/10627-CJFS  

Antioxidative properties go with principal attributes of the Maillard reaction. Biacetyl, a reactive carbonyl intermediate formed in the initial stage of sugar transformations in the presence of amino acids, was found as an efficient precursor of several compounds with significant reducing activity which can act as antioxidants in real food systems. In this work, simple model systems of biacetyl were investigated under different conditions (amino compound involved, concentration, concentration ratio, reaction time, temperature and pH) to gain maximum yield of reducing power. Distribution of reducing power in different fractions of the reaction mixtures...

Copper(II)-complexation by non enzymatically glycated peptides

S. T Seifert, R. Krause, K. Gloe, T. Henle

Czech J. Food Sci., 2004, 22(10):S106-S108 | DOI: 10.17221/10628-CJFS  

The purpose of our work was to examine the metal binding abilities of selected peptide bound Maillard reaction products (MRPs). The N^α-hippuryl-protected MRPs N^ε-fructoselysine and N^ε-carboxymethyllysine were synthesised and measurement of stability constants for complexes formed with the physiologically important metal ions copper(II) and zinc(II) was carried out in aqueous solution (T = 298.1 K; I = 0.1M KNO₃) using pH-potentiometry. The stability constants of N^ε-fructoselysine and N^ε-carboxymethyllysine with Cu(II) proved that new coordination...

Allium discoloration: the nature of onion pinking and garlic greening

R. Kubec, M. Hrbáčová, R. A Musah, J. Velíšek

Czech J. Food Sci., 2004, 22(10):S109-S112 | DOI: 10.17221/10629-CJFS  

Precursors involved in the formation of pink and green-blue pigments during onion and garlic processing, respectively, have been studied. It has been confirmed that the formation of both pigments is of a very similar nature, with (E)-S-(1-propenyl)cysteine sulfoxide (isoalliin) serving as the primary precursor. Upon disruption of the tissue, isoalliin and other S-alk(en)ylcysteine sulfoxides are enzymatically cleaved, yielding prop-1-enylcontaining thiosulfinates [CH₃CH = CHS(O)SR; R = methyl, allyl, propyl, 1-propenyl], among others. The latter compounds subsequently react with amino acids to produce the pigments. Whereas...

Towards a better understanding in acrylamide formation, degradation and reduction in model systems (and foodstuffs)

F. Mestdagh, B. De Meulenaer, C. Van Peteghem, C. Cromphout, O. Thas

Czech J. Food Sci., 2004, 22(10):S11-S14 | DOI: 10.17221/10601-CJFS  

A new baking methodology to study acrylamide formation, based on a closed stainless steel tube reactor, was tested on its repeatability. The main advantage of this frying procedure includes the possibility to study the acrylamide formation mechanism in different artificial mixtures, eliminating some variable factors during frying, such as heat flux, degradation of the frying oil and water evaporation. As a first application of this optimized heating concept, the influence of fat oxidation and fat hydrolysis on acrylamide formation was tested during baking of French fries, as well as during heating in the tube reactor. In both cases, no differences...

Browning reactions between oxidized vegetable oils and amino acids

J. Parkányiová, E. B Hutapea, L. Parkányiová, M. Miyahara, H. Sakurai, J. Pokorný

Czech J. Food Sci., 2004, 22(10):S113-S115 | DOI: 10.17221/10630-CJFS  

Browning of stored food products, not exposed to heat treatment, is generally considered as a negative process. The formation of brown pigments at a temperature close to storage temperatures was followed in mixtures of either free fatty acids or vegetable oils with amino acids, deposited on cellulose fibres. The mixtures were studied at 50°C at free access of oxygen, and the browning process was monitored by reading the absorbance of brown products at 430 nm. Mixtures of free fatty acids and amino acids were turning brown in relation to their unsaturation degree. Mixtures of vegetable oils deposited on cellulose fibres were less coloured than if they...

Maillard reaction products from glucose-methionine mixtures affect iron utilization in rats

C. Delgado-Andrade, I. Seiquer, M. P Navarro

Czech J. Food Sci., 2004, 22(10):S116-S119 | DOI: 10.17221/10631-CJFS  

The influence of Maillard reaction products from glucose-methionine on iron bioavailability was investigated, and compared with those from glucose-lysine (both 40% moisture, 150°C, 90 min). Iron balance was carried out in rats fed diets containing 3% of the different samples and a control diet (AIN93-G). After the balance period, rats were sacrificed, haemoglobin and hematocrit were measured and some organs were removed to analyze iron content. Consumption of the diet containing glucose-methionine heated mixtures increased iron digestibility and bioavailability with respect to animals fed the glucose-lysine diet, although values of net absorption and...

On the significant influence of water on the formation mechanisms of 5-acetyl-3,4-dihydro-2H-1,4-thiazine

W. Engel, P. Schieberle

Czech J. Food Sci., 2004, 22(10):S120-S122 | DOI: 10.17221/10632-CJFS  

The formation of 5-acetyl-3,4-dihydro-2H-1,4-thiazine in Maillard-type reactions of fructose with cysteamine under dry heating and cooking conditions was studied. Labelling experiments with 2-¹³C-fructose revealed, that the formation pathways are completely different, depending on the water content of the mixture. Under dry heating conditions, 5-(1-¹³C-acetyl)-3,4-dihydro-2H-1,4-thiazine is formed almost exclusively with the 2-¹³C of fructose found at the carbonyl carbon of the acetyl group. Under cooking conditions, ADHT is mostly unlabelled and most probably formed from erythrulose. Erythrulose might be generated...

The separation of triacylglycerols using unpolar and medium polar capillary columns

M. Zárubová, V. Filip, J. Šmidrkal, T. Kůtek, I. Piska

Czech J. Food Sci., 2004, 22(10):S123-S126 | DOI: 10.17221/10633-CJFS  

Commercial by supplied triacylglycerols and synthesized triacylglycerols were used in this project. Analysed triacylglycerols with the range of carbon number (CN) 24-54 consisted of saturated and unsaturated fatty acids. Two capillary columns were used in the analyses of triacylglycerols, namely non-polar (Optima^®-1-TG) and medium polar (Optima^®-17-TG) types. In this study the effectiveness of separation (A) of triacylglycerols with different carbon number values, (B) of triacylglycerols with different unsaturation degree, (C) of positional isomers were determined and further possibilities to separate another lipid compounds...

Fluorescence spectroscopy for monitoring rapeseed oil upon heating

P. A. Mas, D. J.-R. Bouveresse, I. Birlouez-Aragon

Czech J. Food Sci., 2004, 22(10):S127-S129 | DOI: 10.17221/10634-CJFS  

The aim of this work was to determine the heating effect on the thermo-degradation process of rapeseed oil (RO) by rapid fluorescence method. Reference measurements were carried out by chromatographic methods in order to compare results with those obtained by fluorescence spectroscopy. The main compounds which were monitored are polar compounds and tocopherols. During heating process, two temperatures were used: 171°C and 189°C for 4.5 h. The results have showed that the tocopherol content decreases, especially at the highest temperature, and the polar content increases of 20% at the end of heating. These results are in agreement with literature. PLS...

Phenolic Compounds of apples in the relation to the postharvest diseases

M. Ducháčková, J. Schovánková, H. Opatová

Czech J. Food Sci., 2004, 22(10):S163-S165 | DOI: 10.17221/10646-CJFS  

This investigation deals with the antifungal activity of naturally occurring phenolic compounds and the metabolism of plant phenolics during the cold storage. In the experiment the apple cultivars with different diseases resistance were analyzed in the relation to changes in phenolic content.

Red wine as resveratrol protective system -

I. Kolouchová, P. Zámostný, Z. Bělohlav, K. Melzoch, L. Siříšťová

Czech J. Food Sci., 2004, 22(10):S166-S168 | DOI: 10.17221/10648-CJFS  

The study describes an isomerization of trans-resveratrol exposed to diffused daylight in dependence on temperature and character of liquid sample (type of solvent, wine …). These effects were investigated using the reverse-phase-HPLC method. Trans-resveratrol isoform was light sensitive and under daylight isomerized to cis-isoform very easily. The exposition of trans-resveratrol solution by higher temperatures did not induce isomerization reaction if that was kept in dark. The wines were analyzed immediately after opening (0 hour), and again after 48 hours and after 17 days. The concentration of resveratrol in tested red wines was stable at...

Transformation of quercetin glucosides in onion and its impact on quecetin bioavailability in humans (abstract only)

W. Wiczkowski, J. Romaszko, A. BUCIÑSKI, H. ZIELIÑSKI, D. Szawara-Nowak, J. Honke, H. Kozlowska, M. K Piskula

Czech J. Food Sci., 2004, 22(10):S169

Onion, a worldwide-consumed vegetable, is a rich source of quercetin. Quercetin shows a number of biological activities that may be beneficial to health. For example it can inhibit platelet aggregation and/or broad spectrum of enzymes and has been demonstrated to have anti-inflammatory properties. Through these actions quercetin may contribute to prevention.

Antioxidant and antiradical activity of extracts of phenolic compounds from red bean

R. Amarowicz, A. Troszyńska

Czech J. Food Sci., 2004, 22(10):S206-S208

Extract of red bean seeds was prepared using 80% acetone. Crude extract was applied onto a Sephadex LH-20 column. Fraction I of low molecular weight phenolic compounds was eluted from the column by ethanol. Fraction II of tannins was eluted from the column using water-acetone (1:1, v/v) as a mobile phase. Phenolic compounds present in the extracts and in the fractions I and II showed antioxidant and antiradical properties investigated using a β-carotene-linoleate model system, and DPPH radical scavenging activity. Crude extract showed the highest antioxidant activity in a β-carotene-linoleate model system. However, tannins fraction was the...

Antioxidant and pro-oxidant activity of coffee as affected by torrefacto roast

I. López-Galilea, S. Andueza, M. P. De Peña, C. Cid

Czech J. Food Sci., 2004, 22(10):S209-S211 | DOI: 10.17221/10662-CJFS  

The addition of sugar at the end of the torrefacto roasting process could influence on the antioxidant and pro-oxidant properties of coffee because sugar is one of the main precursors of Maillard reaction. The aim of the work was to study and compare the antioxidant and pro-oxidant properties of some commercial roasted coffees which are selected to represent conventional roasted coffee and torrefacto roasted blends. When the percentage of torrefacto coffee was increased, the antioxidant activity increase and a slight tendency to decrease the pro-oxidant activity were observed. Moreover, a principal component analysis allowed to separate (a) brands...

Peroxyl radical scavenging activity of soluble high molecular weight fraction from coffee brews

C. Delgado-Andrade, F. J Morales

Czech J. Food Sci., 2004, 22(10):S212-S214 | DOI: 10.17221/10663-CJFS  

Roasting process of coffee beans affects the final composition of coffee brew. While the presence of some of its antioxidant compounds (phenolic acids) decrease throughout the treatment, melanoidins are formed during the thermal process. Recent research into nutritional, physiological and functional properties of melanoidins has suggested that they have antioxidant activity. Instant coffees produced from roasted coffee beans were obtained from a company coffee in three different roasting degrees: light (CTn 110), medium (CTn 85) and dark (CTn 60). Melanoidins of high molecular weight (> 10 000 Da) were obtained from each coffee, as well as pure...

Antioxidative and antimicrobial effects of some natural extracts in lard

S. Sekretár, Š. Schmidt, M. Vajdák, L. Zahradníková, J. Annus

Czech J. Food Sci., 2004, 22(10):S215-S218 | DOI: 10.17221/10664-CJFS  

The extracts from 17 ready available plants were prepared by 95% ethanol extraction in Soxhlet extractor. The crude extracts were examined for their antioxidation properties using the automatized swift test (Rancimat) and lard as a substrate. The extracts with the most promising results (Rosmarinus officinalis and Salvia officinalis) were chromatographed on silica gel column and the fractions so obtained were explored separately. Second fraction from the chromatography of rosemary extract exhibited the antioxidation activity (induction period 8 h at 0.002% wt.) comparable with the activity of butylated hydroxytoluene (BHT) at 12.5...

Changes of furanocoumarins content in vegetables during storage

P. Botek, V. Schulzová, R. Peroutka, J. Hajšlová

Czech J. Food Sci., 2004, 22(10):S219-S222 | DOI: 10.17221/10665-CJFS  

Long term experiments, which simulated storage of celery (Apium graveolens) under industrial (airconditioned store)/household (common cellar) conditions, were carried out. Several celery cultivars from both organic and/or conventional production were monitored for furanocoumarins levels for 16-26 weeks. The increase of furanocoumarin concentrations during the storage of all the tested celery cultivars was observed, nevertheless, the extent of toxicants accumulation differed among tested cultivars. The changes of furanocoumarin levels occurring during processing of vegetables were studied, too. Levels of both linear (psoralen, bergapten, xanthotoxin,...

Factors affecting the formation of acrylamide in coffee

K. Bagdonaite, M. Murkovic

Czech J. Food Sci., 2004, 22(10):S22-S24 | DOI: 10.17221/10604-CJFS  

Four types of green coffee beans (Robusta and Arabica) were roasted in a laboratory roaster and in an oven. The samples were analysed for acrylamide using liquid chromatography with UV detection. Significant difference in acrylamide content was observed in different coffee types. Robusta coffee beans, roasted to different degrees of browning contained more acrylamide than Arabica varieties. Roasting time and temperature had a great influence on the acrylamide formation in coffee beans. Coffee beans roasted for longer time had less acrylamide. Additionally, coffee beans roasted at higher temperatures contained less acrylamide compared to those roasted...

Changes of phytoestrogens daidzein, genistein and their glycosides daidzin and genistin and coumestrol during processing of soyabeans

J. Lojza, V. Schulzová, J. Hajšlová

Czech J. Food Sci., 2004, 22(10):S223-S226 | DOI: 10.17221/10666-CJFS  

Phytoestrogens represent biologically active compounds showing estrogenic activity similar to that of sex hormones - estrogens. Various adverse effects such as sterility, increase of females' genitals, lost of males' copulation activity, etc. were observed in farm animals after exposure to higher amounts of fodder containing phytoestrogens. On the other side, their presence in human diet is nowadays the object of many research studies concerned with prevention of breast and prostate cancer, osteoporosis and other hormone-linked diseases by dietary intake of phytoestrogens. Soya (Glycine max) is one of the main sources of these compounds in...

The effect of chemical modifications on rheological properties of collagen from of baltic cod (Gadus morhua) skin stabilized by interaction with κ-carrageenan

R. Tylingo, M. Sadowska

Czech J. Food Sci., 2004, 22(10):S227-S230 | DOI: 10.17221/10667-CJFS  

The κ-carrageenan-collagen complex was precipitated by κ-carrageenan from solution of collagen sourced from Baltic cod (Gadus morhua) skin in 0.5M acetic acid. The influence of glutaraldehyde or EDC [1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride] concentration on rheological properties of κ-carrageen-collagen complex was examined. At 5 to 30mM glutaraldehyde content in 0.5 κ-carrageenan-collagen dispersion a rapid increase in its viscosity was observed, which remained unchanged over 120 min. Further increase in glutaraldehyde concentration to 30mM caused enhanced viscosity and shorten time of complex stability,...

Chitin-glucan complex from Agaricus blazei, a potential raw material for production of food additives

P. Blafková, A. Synytsya, J. Čopíková

Czech J. Food Sci., 2004, 22(10):S231-S234 | DOI: 10.17221/10668-CJFS  

Agaricus blazei, a mushroom native to Brazil, is a perspective source for food industry. This mushroom has been widely used in folk medicine due to its possible medicinal value. The most important components of fruiting bodies of A. blazei are specific β-glucans with β-(1→3), β-(1→4) andβ-(1→6) glycosidic linkages. These polysaccharides are supposed to be responsible for some healthy properties of mushrooms (anticarcinogenic and antimutagenic ones). β-Glucans are associated with chitin forming water-insoluble chitin-glucan complex. This complex was isolated from fresh and dried mushrooms (separately...

Amino-dealkoxylation of hm citruc pectin with n-alkylamines: a kinetic study

L. Sihelniková, A. Synytsya, J. Čopíková

Czech J. Food Sci., 2004, 22(10):S235-2S37 | DOI: 10.17221/10669-CJFS  

Pectins are plant polysaccharides that are widely used in food industry. Chemical modification of pectins influences their technological properties. Amidated pectins are important pectin derivatives with good gelling properties at low-sugar conditions. The common method of pectin amidation is ammonolysis of methyl ester groups of highly methoxylated (HM) pectins in heterogeneous reaction with ammonia in methanol. Aminodealkoxylation (aminolysis) of HM pectin with primary amines leads to the formation of N-alkylpectinamides. The reaction yield of aminolysis depends on reaction time, temperature and the pectin/alkylamine ratio. The reaction...

Protective effects of components in peanut skins against d-galactosamine-induced rat hepatic injury

T. Matsubara, K. Todoroki, T. Yamaki, K. Ookuma, H. T. T. Nguyen, M. Miyahara, H. Kumagai, J. Pokorný, H. Sakurai

Czech J. Food Sci., 2004, 22(10):S203-S205 | DOI: 10.17221/10660-CJFS  

The water extract powder (WEP) from normal oleic acid peanut skins at a dose of 200 mg/kg significantly inhibited the increases of serum bilirubin and the serum concentrations of AST, ALT, and GGT, marker enzymes for liver injury, in D-galactosamine (GalN)-induced liver injury rats. However, the WEP from high-oleic acid peanuts skins appeared to be less effective than that from normal ones at the same dose. trans-Resveratrol (0.67 mg/kg) and quercetin (0.67 mg/kg) were used for comparison. Their protective effects were as strong as that of the WEP from normal oleic acid peanut skins. These results indicated the ability of the WEP of peanut...

Enzyme-linked immunosorbent assay for the determination of isoflavones in alimentary important plants

M. Vítková, Z. Macková, R. Koblovská, O. Lapčík

Czech J. Food Sci., 2004, 22(10):S199-S202 | DOI: 10.17221/10659-CJFS  

The development of polyclonal antibody-based enzyme-linked immunosorbent assays (ELISA) for the determination of individual isoflavones, i.e. daidzein, genistein and biochanin and their homologues, is presented in this work. Isoflavone conjugates with bovine serum albumin were used as immunogens, coupled at the position C 7 and C 4' via a carboxy methyl spacer. The developed ELISAs are highly specific, I₅₀ values of the standard curves range between 0.3-1.2 ng/ml. The cross reactivities to other isoflavones are in acceptable range and the interference of non-isoflavonoid molecules is negligible. The immunoassays have been used for monitoring...

Effect of boiling on yellow onion quercetin (glucosides

K. Nemeth, M. K Piskula, M. Takacsova

Czech J. Food Sci., 2004, 22(10):S170-S172 | DOI: 10.17221/10649-CJFS  

Flavonoids are a large group of secondary plant metabolites with hydroxyl groups. The flavonol quercetin is commonly found in onions. In the edible fleshy scales of yellow onions quercetin mono- and diglucosides are present. The aim of this work was to study quercetin glucosides during technological processing of yellow onion bulb. Onion was boiled in water under reflux for 30 min. The cooking was performed at three different onion/water ratios (1/5, 1/10, 1/20; w/w). The resulting soup, boiled onion solids and the control raw onion samples were lyophilised, extracted with ac. methanol and analysed for quercetin and its derivatives (3-β-D-glucoside,...

Determination of phytic acid by capillary isotachophoresis combined with capillary zone electrophoresis (abstract only)

V. Prokorátová, F. Kvasnička, V. Beková

Czech J. Food Sci., 2004, 22(10):S173

The aim of this work was to find convenient method for detection of plant material in meat products. The adulteration of meat products is still actual problem, because meat products are cheaper with plant material. The Decree No. 264/2003 of the law No. 110/1997 is dealing with meat and meat products. The methods used for assessing plant material in food are based on the determination of some characteristic plant constituents such as proteins, flavonoids, sitosterol, cellulose, cellobiose, α-(1,6)-galactosyl-oligosaccharides and DNA. The main disadvantage of these methods is complicated sample treatment before analysis. Phytic acid (myo-inositol-1,2,3,4,5,6-hexakisdihydrogenphosphate)...

The sensory quality of sprouts obtained from the selected species of legume seeds

A. Troszyńska, G. Larski, A. Kosińska

Czech J. Food Sci., 2004, 22(10):S174-S176 | DOI: 10.17221/10652-CJFS  

Sensory characteristics (evaluated by quantitative descriptive analysis and as the hedonic ratings) of sprouts obtained from lentil, Mung bean, pea and soybean sprouts were assessed. It was found that the palatability of sprouts was negatively correlated with bitterness and astringency of these products. However, the statistically significant correlation between the content of total phenolic compounds and negative sensory attributes (bitterness and astringency) was not found.

Amaranth seed extraction by propan-2-ol after enzymatic treatment

M. Veselá

Czech J. Food Sci., 2004, 22(10):S177-S178 | DOI: 10.17221/10653-CJFS  

A process of amaranth seed grinding followed by extraction was studied. For fat emulsion stability impairment the enzyme G-Zyme^®G999 was used. Using this process the improved fat separation was achieved.

Efficiency of activity antioxidants in flaxseed oil and borago oil and their triacylglycerols

K. Mińkowski

Czech J. Food Sci., 2004, 22(10):S179-S182

It was stated that plant oils rich in alpha linolenic acid (flaxseed oil) and γ-linolenic acid (borago oil) become subject to oxidation processes very easily. One of the methods to increase their oxidative stability is to introduce antioxidants. In this work addition of antioxidants resulted each time in longer induction period depending on kind and dose applied. The mixture of alpha tocopherol, ascorbyl palmitate and lecithin was the most effective both in flaxseed oil and borago oil.

Changes in quality and antioxidant properties of dry sausages produced by type and dosis of paprika

I. Revilla, A. M Vivar-Quintana

Czech J. Food Sci., 2004, 22(10):S183-S186 | DOI: 10.17221/10655-CJFS  

The objective of the study was to evaluate the effect of the highest doses of paprika and the different percentage of hot paprika on curing process of dry sausage "Chorizo Zamorano" evaluating texture, colour and antioxidant properties. Four types of dry sausage were elaborated, control made with 1.8% of intermediate hot paprika, Zam0% made with 2.8% of intermediate hot paprika, Zam15% made with 2.38% of intermediate hot and 0.42% of hot paprika and Zam30% made with 1.96% of intermediate hot and 0.84% of hot paprika. The results showed that increasing paprika doses and percentage of hot paprika, affect the curing process, resulting in a faster decrease...

Study of irradiated black pepper antioxidant activity changes

M. Suhaj, J. Rácová

Czech J. Food Sci., 2004, 22(10):S187-S190 | DOI: 10.17221/10656-CJFS  

Some antioxidant activities of extracts of irradiated black pepper (Piper nigrum) were evaluated. The ground black pepper was exposed to gamma-irradiation at doses from 5 to 30 kGy. The effect of irradiation on antioxidant properties of black pepper extracts was investigated by these methods: radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, determination of reducing power, thiobarbituric acid reactive substances assay and electron paramagnetic resonance spectroscopy (EPR). Irradiation resulted in a decrease of DPPH antiradical activity of black pepper extracts according to dose of irradiation. Reducing power was...

Ways to reduce the acrylamide formation in cracker products

M. Vass, T. M Amrein, B. Schönbächler, F. Escher, R. AMADÒ

Czech J. Food Sci., 2004, 22(10):S19-S21 | DOI: 10.17221/10603-CJFS  

The sources of reducing sugars and free asparagine of two different cracker products were identified, and acrylamide formation during baking was measured. The application of an asparaginase decreased the acrylamide content by at least 70% in both products. Replacing ammonium hydrogencarbonate by sodium hydrogencarbonate as baking agent and replacing reducing sugars by sucrose resulted in almost 80% less acrylamide in the wheat cracker. Decreasing free asparagine and reducing sugars in the ingredients and a lower end-temperature during baking lowered the acrylamide content of the potato cracker by about 50%.

Green and roasted coffee antiradical activity stability in chemical systems

M. Daglia, A. Papetti, G. Gazzani

Czech J. Food Sci., 2004, 22(10):S191-S194 | DOI: 10.17221/10658-CJFS  

The stability to storage at different temperature and oxygen exposure of green and roasted coffee either as coffee beans or as ground coffee antiradical activity, was evaluated. The results showed that the coffee solution antihydroxyl radical activity was constant, independently from the coffee species, from the roasting process, and moreover from the type of storage conditions, suggesting that temperature and oxygen exposure did not affect this antiradical activity. With regard to antiperoxyl radical activity, all green coffee solutions showed remarkable and stable activity. Conversely, the roasted coffee beans and roasted and ground coffee antiperoxyl...

Influence of phenolic compounds on sensory parameters of tea infusions

P. Košulič, J. Pokorný, Z. Panovská

Czech J. Food Sci., 2004, 22(10):S195-S198 | DOI: 10.17221/10657-CJFS  

A set of 9 black teas and 10 green teas were analyzed. Sensory parameters of tea infusions were correlated with the content of total polyphenols (determined after Folin and Ciocalteu) and sensory parameters (determined after ISO standards). Total polyphenols affect both the astringency and the bitterness of green tea and black tea infusions. The relations are mainly semilogarithmic, but very close to linear. Sucrose decreased the astringency by 30-40%, and the bitterness was suppressed still more.

Monoacylglycerols as food additives with antimicrobial properties

E. Bartošová, R. Červenková, Z. Špičková, J. Šmidrkal, V. Filip, M. Plocková

Czech J. Food Sci., 2004, 22(10):S238-S241 | DOI: 10.17221/10670-CJFS  

The antimicrobial activities of monoacylglycerols (MAGs) with different lengths of hydrophobic hydrocarbon chains (1-decanoylglycerol, 1-undecanoylglycerol, 1-dodecanoylglycerol, 1-tridecanoylglycerol, 1-tetradecanoylglycerol) were investigated. Food undesirable bacterial strain Bacillus subtilis DMF 2006 and mould strains Aspergillus niger DMF 0501 and Fusarium culmorum DMF 0103 were used as indicator strains in order to determine antimicrobial properties of monoacylglycerols. The strongest antibacterial effect was caused by 1-undecanoylglycerol, 1-dodecanoylglycerol, 1-tridecanoylglycerol. These substances inhibited growth...