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An improved routine, simple and sensitive method is presented for the determination of free and bound 3-chloropropane-1,2-diol (3-MCPD) in different foods using capillary gas chromatography with mass spectrometric detection and deuterated 3-MCPD as internal standard. The optimised method was linear within the working calibration standard concentrations in the range of 0.009-1.3 mg 3-MCPD per 1 kg of sample. The LOD and LOQ were 0.003 µg/kg and 0.009 µg/kg, respectively. Validation of the method was carried out by analysing standards of 3-MCPD, acid-HVP, roasted coffee samples, and the same samples spiked with 3-MCPD. Repeatability (expressed as RSD) of the method was in the range 1.0-4.2%, the average spike recoveries were 99.1-99.5% (RSD = 0.8-1.4%), respectively. 3-MCPD bound in esters with higher fatty acids was isolated as fat, the isolated fat was subjected to methanolysis and 3-MCPD generated was quantified using the same method. The LOD and LOQ were determined to be 1.1 mg/kg of lipids and 3.3 mg/kg of lipids, respectively. Using the optimised method, 20 samples of retail food products were analysed for their free and bound 3-MCPD. All samples contained free 3-MCPD at 9.6-83 µg/kg (RSD = 0.4-7.0%). The level of the bound 3-MCPD varied between the LOD and 2.4 mg/kg with RSD = 0.3-2.4%.

The Maillard reaction, or nonenzymatic browning, includes a complex network of reactions initiated by the condensation reaction of a carbohydrate and an amino compound, and is of utmost importance for the formation of flavour and colour in thermally treated foods. Besides volatile flavour compounds, also brown-coloured polycondensation products, named melanoidins, are produced. In latest years, the interaction of lipid oxidation products in the classical Maillard reaction pathway and vice versa is of particular interest, since it has been shown that the course of both reactions can be modified by the reactants, intermediates and products of the other (ZAMORA & HIDALGO 2005). Therefore, in parallel with the formation of model melanoidins, polycondensation products resulting from the interaction of amino acids with lipid oxidation products were studied. For this purpose, various coloured water-soluble high molecular weight and water-nonsoluble reaction products were isolated from the model reactions of glycine or lysine with a lipid oxidation product (hexanal, (2E)-hexenal, (2E,4E)-decadienal) in the presence or absence of glucose. They were characterised by UV-visible absorbance measurements, elementary analysis, and thermal degradation followed by SPME-GC-MS analysis (ADAMSet al. 2003). The UV-visible absorbance spectra before and after dialysis indicated that the most important contributors to the formation of water-soluble coloured material were constituents of the low molecular fraction. Elementary analysis data showed that a higher amount of nitrogen was incorporated in the high molecular weight fractions as compared to the water-nonsoluble fractions, except for the water-nonsoluble reaction products from amino acid/(2E, 4E)-decadienal interactions, which demonstrated the lowest C/N ratio found. Volatile carbonyl compounds, furans, a liphatic compounds, pyridines, pyrroles and benzene derivatives were the main groups of compounds identified in the thermal degradation profile of each fraction tested. Aldol condensation reactions of the carbonyl compounds were very important in the initial reaction steps. Especially pyridines seem typical indicators of amino acid-lipid oxidation product interactions.

Cocoa liquor used in the confectionery industry comes from a wide range of geographical areas and may have different chemical compositions, sensory properties, and nutritional values. We found it interesting to study the polyphenolic content and composition of cocoa liquors for their potential use in industrial production. Six defatted samples originating from different countries were extracted with aqueous methanol (70%, v/v), and the polyphenolic profiles were determined using RP-HPLC method. According to our results, all samples of cocoa liquors have similar polyphenolic profiles, however, quantitatively varied. In the samples, about 13 compounds were identified by comparison of their retention times and UV spectra, and the quantified peaks were (+)-catechin, (-)-epicatechin, (-)-gallocatechin, (-)-epigallocatechin, caffeic acid derivative, caffeine, and theobromine. Also, several peaks were identified as oligomeric procyanidins. The free-radical scavenging activity was determined by the DPPH* (1,1'-dipheny-2-picrylhydrazyl) and Oxygen Radical Antioxidant Capacity (ORAC) assays. The order of antioxidant activity of the cocoa liquors studied was the same with both methods (Madagascar > Mexico > Ecuador > Venezuela > Sao Tome > Ghana samples). In addition, correlation between the antioxidant capacity and polyphenolic content was also determined, a high correlation coefficient having been obtained by both methods (R^{2 = 0.9868 for DPPH, and 0.9375 for ORAC).}

Phytosterols and -stanols are added to food products because of their known ability to lower serum cholesterol levels. They are applied either in their free or esterified forms, i.e. as fatty acid esters. Sterols are known to form variety of oxidation products under exposure to heat, light and metal contaminants, for example in food processing conditions. Since these oxides may have adverse health effects, the oxidation process needs to be studied. Until recently, sterol oxidation studies have concentrated on following the formation of secondary oxidation products in free sterol and steryl esters, but little is known about the oxidation of steryl esters as intact molecules. The aim of this experiment was to study primary autoxidation of intact steryl ester by measuring hydroperoxide formation in bulk cholesteryl ester. Cholesteryl linoleate was maintained at 60°C for 0-72 h after which formed hydroperoxides were determined with normal phase high performance liquid chromatography connected to diode array detector (HPLC-DAD). Also peroxide value (PV) was measured to indicate the total amount of formed hydroperoxides. With HPLC method steryl ester -OOH's could be analysed as intact esters, without saponification. A gradient elution was performed with 0.3-10% methyl-tert-butyl ether (MTBE) in heptane followed by cleanup with 30% MTBE. Compounds were detected with DAD at wavelengths 206 nm and 234 nm. Peroxide value indicated that the formation of hydroperoxides reached the maximum after 12 h of prolonged heating. According to HPLC data, at this time point less than 10% of the hydroperoxide groups were located in the sterol moiety and more than 90% in the fatty acid chain. The proportion of sterol-OOH's increased as the heating continued; at 24 h 20% and at 48 h 30%. However, after 72 h no hydroperoxides were observed. In conclusion, oxidation of cholesteryl linoleate started in the fatty acid moiety and as the reaction progressed more of the sterol -OOH's were observed, though at all time points fatty acid -OOH's were dominating.

The influence of microwave heating (microwave oven Electrolux, 2450 MHz, 400 W) from 8 up to 24 min on the oxidation and fatty acid composition of lipids of common carp (Cyprinus carpio) and Atlantic mackerel (Scomber scombrus) minced fish flesh were studied. The heating treatment at all conditions reduced moisture and therefore, increased lipid and dry matter contents. The isolated lipids were subjected to the following analyses: peroxide value, acid value and content of conjugated dienes (by absorbance at 232 nm). The free fatty acid content in the lipid fraction of the fish flesh was significantly reduced by cooking. Conjugated diene levels in fish muscle increased and peroxide values decreased for all cooked samples. Changes in fatty acids composition were only small.

The presence of masked or hidden forms of Fusarium mycotoxins (deoxynivalenol, DON, zearalenone, ZEN and fumonisins B1, B2 and B3) were studied in wheat and maize derived products. Significant amounts of these forms were found both in raw and in processed food commodities. Deoxynivalenol-3-glucoside was found in wheat products up to 30% of DON concentration. Bound forms of fumonisins often account for an equal or even higher amount in comparison with the free forms.

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.

Objective of this work was determination of processing contaminant known as 3-MCPD (3-chloropropane-1,2-diol) in its free and bound form in breads with defined parameters of processing. Selected and analysed were 24 samples, which represented two sets of breads produced in bakeries equipped with a continual line. In all cases determinations were carried out for breadcrumb and crust separately. The first set of samples were wheat-rye breads produced chronologically in ten days in the bakery Michelská pekárna, slightly different in temperatures and times of baking. The second set contained 14 samples of wheat-rye breads with a content of rye flour less than 40% differing in the yeast type and acidity. These breads were produced in the bakery Kontinua. The fat content was determined in all samples by Soxhlet extraction. Free and bound 3-MCPD was determined by gas chromatography-mass spectrometry method. Concentration of free 3-MCPD in samples was at interval < 9-54.5 μg/kg. Concentration of bound 3-MCPD was at interval 1.56-23.60 mg/kg of fat (i.e. 5.7-84.9 μg/kg of sample).

The roasting process allows complex chemical reactions in foods leading the formation of the Maillard-related compounds, which are of fundamental importance for colour and aroma development in hazelnuts (Corylus avellana L.). Colour is a charming characteristic of roasted foods; despite of their fundamental role in organoleptic properties, the roasting allows accumulation of some potentially toxic technological contaminants, as showed in other matrices (e.g. acrylamide, furan and D-amino acids). Free and protein-bound D-amino acids (D-aa) in foods can origin by technological processing (their formation is pH, time, and temperature-dependent), and also from bacterial racemases in fermented foods, as recently showed in cocoa ( FRIEDMAN 1999; CALIGIANI et al. 2007) So, these compounds can be used as thermal and bacterial markers. Racemisation impairs digestibility/nutritional quality of foods; some D-aa acids are both beneficial and deleterious (DA-WEN SUN 2008). The L*a*b* (international standard for colour measurements adopted by the Commission Internationale d'Eclairage, CIE, 1976) and Red Green Blue (RGB) systems are the most employed methods for colour analysis. Computer Vision Image Analysis (CVIA) coupled with Artificial Intelligence (AI) and related tools (Principal Component Analysis, Artificial Neural Networks, Self Organising Maps) should be considered a powerful approach for evaluating colour development in foods (PATZOLD & BRUCKNER 2006). First aim of our study was to monitor via GC-MS the D-aa formation in hazelnuts during different conditions of roasting. Second aim was to develop a CVIA/AI method to study the colour development in roasted hazelnut, considering the correlation between colour and D-aa too. The racemisation of L-aa (particularly D-aspartic acid plus D-asparagine, D-asx) in hazelnut was time-temperature dependent. Protein-bound D-asx (expressed as D/(L+D); 1.49%) and free D-ala (5.87%) were predominant in Infra-Red roasted samples. Hot-air flow process leads the formation of free-D-aa (D-ala: 6.77%; D-asx: 3.47%; D-glu: 4.50%). Using Back Propagation Neural Network on the Discrete Fourier Transform output (whole surface colour), the identification of hazelnuts samples roasted in different condition was achieved. Red colour decreased according to the correspondent increase of D-amino acids content. Concluding, CVIA/AI is a promising complex tool useful to simplify the comprehension of a complex model system, as colour development in roasted hazelnuts. Keywor

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 in the cheese. Capric, myristic, palmitic, stearic and oleic acids represented the largest proportion of acid content and the most significant changes during ripening.

Printing inks contain many substances, the use of which is not allowed in food contact materials. Recently the migration of printing ink constituents from the printed packaging materials into food either through the packaging material or via the set-off phenomenon has been reported. The aim of presented study was to quantify the transfer of selected printing ink plasticisers, i.e. acetyl tributyl citrate (TBAC), bis(2-ethylhexyl) adipate (DEHA), bis(2-ethylhexyl) phthalate (DEHP), 2-ethylhexyl diphenyl phosphate (EHDPP) and tributoxyethyl phosphate (TBEP), from printing of packaging materials into food simulants. Two polymer packaging films, i.e. polyethylene film (LDPE, thickness 50 μm) and laminated polyethylene terephthalate and polyethylene film (PET/LDPE 12 μm/35 μm) were printed with flexography technique to obtained the packaging materials with defined content (0.05 mg/dm² and 0.5 mg/dm²) of free above mentioned substances in printing layer. The migration of the tested additives through the packaging films into distilled water and 95% ethanol was studied at 6°C and 23°C. The set-off transfer of all plasticisers into LDPE film in contact with printing was tested at 23°C and 40°C. The results confirmed quite easy migration of all tested additives into 95% ethanol through the LDPE film when more than 90% of the total amount of TBAC and DEHP in printing was extracted into the stimulant during 30 day storage at 23°C at both content levels. Lower migration was found for DEHA (i.e. about 86% and 55% for higher and lower content in printing, respectively), TPEC (about 62% and 50%) and EHDPP (69% for lower content in printing). The migration through the laminated PET/PE film was generally about two thirds of that for LDPE film with an exception of DEHA. For DEHA migration through the both tested films were comparable. As expected the plasticiser transfer into distilled water was about 5-10 times slower compared with the migration into 95% ethanol. Surprisingly high levels of the set off transfer from printing into LDPE film at 40°C after 30 days were determined for all tested plasticisers. The found levels of plasticiser transport were as follows: 32%-40% for TBAC, 28% for DEHP, 25% for DEHA, 12% for TBEP and about 2% for EHDPP. The study confirmed the fact that composition of printing inks can significantly influence the safety of food packaging materials and the necessity of acceptation of suitable legislation for the quality control of printing inks for food packages.

: Coho salmon (Oncorhynchus kisutch) has recently attracted a great interest as a farmed product. This research focuses on its commercialisation as a frozen product. For it, an advanced storage technology combining vacuum and a polyphenolic rich-film was applied for a 9-months storage period (-18°C). The study was addressed to lipid hydrolysis and oxidation changes and to endogenous antioxidant content in salmon muscle. No effect of packaging conditions could be observed on free fatty acid formation. However, vacuum packaging conditions provided a partial inhibition of primary (peroxide) and secondary (anisidine value) lipid oxidation development; this inhibitory effect was accompanied by a lower tocopherol isomers loss. The employment of a film including polyphenolic compounds led to a partial inhibition of α-tocopherol breakdown and to a lower secondary (anisidine value) and tertiary (fluorescent compound formation) lipid oxidation development. A partial inhibitory effect on lipid oxidation development is concluded for the employment of a polyphenolic compound rich-film packaging when applied to farmed coho salmon.

The reaction of glyoxal with nucleophilic amino acids was monitored for β-casein as well as β-lactoglobulin. As predicted from previous experiments with hippuryl amino acids, a measurable decrease of arginine can be found in the thiol-free β-casein, while the lysine content remained almost unchanged. For β-lactoglobulin, the incubation with glyoxal led to a slight decrease in the lysine content, while the arginine residues remained unmodified. Here, in accordance with nucleophilicity, it is suggested, that mainly cystein residues react with glyoxal. In solutions containing β-casein with or without glutathione, the effects were less pronounced and regarding the lysine and arginine content, the influence of thiols could hardly be recorded on a significant level. However, comparing the CML levels in the different incubations, it becomes obvious, that glutathione is favouring CML formation in a concentration depended manner. Therefore, the use of CML as an indicator, e.g. for the Maillard reaction, must be related to the composition of the reaction system.

Antioxidant capacity of foods and food supplements based on berries and flowers of medicinal plant elderberry (Sambucus nigra L.) was assessed. Reducing properties of the samples and extracts were evaluated using amperometric detection at working electrode potential -0.8 V after HPLC separation. Moreover, antiradical activity of selected samples was determined by the means of spectrophotometric DPPH radical scavenging method. Electrochemical activity (EA) of fresh juice pressed from elder fruits amounted to 0.71 g AAE/l with anthocyanins as minor contributors (10.2%). Catechins and phenolic acids were the major active groups. During production of elder berry spread, even more than 90% of the EA compounds found in raw elder berry material can be destroyed. Comparable activity may be found also in the products from elder flowers. Although elder blossom syrups possessed similar EA regardless of the technology used (0.033-0.054 g AAE/kg), their chromatographic patterns were often very different. For example, no flavonols were present in the syrups, if traditional preparation comprising 24-h maceration with citric acid was applied. Analyzing the chromatographic patterns, one can distinguish different base materials and technology, which can be used for the authenticity confirmation. Herbal infusions from elder flowers, which contain more flavonols than are in syrups, were 16-27 times richer in EA than drinks prepared from the syrups after recommended dilution. Only the syrup designed for preventing and treating upper-respiratory viral infections showed the EA (0.09 g AAE/kg) comparable to that of herbal infusion (0.13 g AAE/l).

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%.

The applicability was evaluated of 16 different oats species and varieties of different provenance in the coeliac diet in view of the composition of the protein complex and immunological testing during two-year experiments (2001 and 2002). Determination was carried out of total nitrogen content (average of evaluated oats collection in 2001 was 2.21%, in 2002 2.78%), protein nitrogen content (average 2001 1.94%, 2002 2.28%), and crude protein (N × 6.25) content (average 2001 13.80%, 2002 17.37%). The proportions of different protein fractions play a decisive role for the aims of this study because, based on the existing knowledge, coeliacally active protein components are present particularly in the prolamin fraction. The percentage of prolamins (determined by discontinual fractionation after Osborne) in the author's evaluated collection of oats species and varieties under the conditions of Central Bohemia reached on average 17.68% of the total protein in 2001, and 15.36% in 2002. The average percentage of albumins and globulins of the total protein reached 36.97% in 2001 and 41.04% in 2002, the average percentage of glutelins of the total proteins was 37.61% in 2001 and 34.10% in 2002, and residual was on average 7.55% in 2001 and 8.70% in 2002, respectively, of the total protein. Electrophoretic analysis of reserve (gluten) proteins (SDS-PAGE ISTA) showed in the oats collection evaluated the percentage of LMW + prolamins in the range 56-77% of the total reserve proteins in 2001, and 52-73% in 2002. The results of A-PAGE electrophoretic analysis of prolamin proteins confirmed the presence of α-prolamins, that ranged in the total content of prolamins from 50 to 88% in 2001, and from 77 to 100% in 2002, while β- + γ-prolamins ranged in 2001 from 11 to 49%, and in 2002 from 0 to 22%. These values do not give serious guarantees for the possible utilisation of oats in the gluten-free diet. The results of the immunological evaluation of the amount of prolamins in oats grains using ELISA showed great differences between different varieties and the experimental years. In 2001, 7 oats samples out of 13 evaluated, and in 2002 10 samples out of 12 evaluated were below the limit for the gluten-free diet (10 mg prolamins (gliadins)/100 g of sample dry matter), but the other varieties exceeded the limit, particularly in 2001, very significantly. The results obtained in the evaluated collection of species and varieties of oats revealed a great variability in the structure of the protein complex and in the immunological testing. In addition a significant effect of the year on the results of all analyses was evident. Based on our results, the use of oats in the diet for coeliac disease can be very risky for these reasons.

The composition and selected physical and chemical parameters of 44 samples of fresh goat cheeses produced on a farm in the Czech Republic were determined. The following average values were obtained for the parameters analysed: pH 4.87 ± 0.14, titratable acidity (SH) 98.09 ± 4.93, dry matter 46.83 ± 1.57%, fat in dry matter 52.74 ± 5.24%, sodium chloride (NaCl) 2.08 ± 0.54%, and a_w 0.979 ± 0.007. All samples showed excellent sensory characteristics and their compositions corresponded to those declared by the producer. Microbiological tests were used for the detection of Enterobacteriaceae spp., lactic acid bacteria, Escherichia coli, Enterococcus spp., Staphylococcus aureus, Bacillus cereus, Salmonella spp. and Listeria monocytogenes. Under the applicable regulations, the analysed fresh goat's cheeses were microbiologically safe and had the appropriate physical and chemical characteristics.

Proteolysis is the principal and most complex biochemical event occurring during the maturation of the majority of ripened cheese varieties. In addition to softening the cheese body, proteolysis influences the development of cheese flavour via the formation of amino acid and peptides which make a direct contribution to flavour. Goat, cow and sheep cheeses have been elaborated with raw milk and calf rennet. The extent of proteolysis was monitored over six months of ripening and means of HPLC peptide profile analysis. The influence of season on the changes in hydrophobic and hydrophilic peptides and the HO/HI ratio during the ripening of the cheeses were studied.

The aim of this study was to investigate the contamination of beer of Slovak origin with fumonisins. A suitable analytical procedure was suggested - the limit of detection at the level close to 1 µg/l was achieved for both fumonisins B₁ and B₂. The recovery was determined at 93% for fumonisin B₁ and at 78% for fumonisin B₂. Fluorescence detection was used after derivatisation with a mixture of o-phthaldialdehyde and 2-mercaptoethanol. Phosphate buffer usually applied resulted in a poor separation of derivatised fumonisins. Peak splitting was observed depending on the pH of the eluent. The pH value of 2.6 was found suitable for the peak splitting elimination. A convenient gradient elution metod was suggested avoiding the possible interference in fumonisin contents determination. For the preparation of samples, immunoaffinity cleaning procedure was applied. Beer samples from all domestic producers were analysed. The content of fumonisins determined was under the limit of detection in all cases. All the beers tested were produced from the barley grown in 2003.

Taste is the chemical sensation whose function is not very well known. Recently it was shown that the range of taste is more extensive than the five basic taste sweet, salty, bitter, sour and umami. A metallic taste has been suggested as another basic taste, but its mode of perception is not well understood and has not been really accepted in the taste literature. Ferrous sulphate solutions were presented to the assessors so their sensitivity and best estimate thresholds (BET) were measured. The best estimated threshold range was 0.00049-0.00669 g/l for demineralised water, 0.00079-0.00669 g/l for distilled water and 0.00108-0.00669 g/l for tap water.

Total number of 104 canned soft drinks collected from several regions in Turkey were analysed. The purpose of this study was to determine the levels of heavy metals in the drinks commonly consumed in Turkey. Quantitative determination of heavy metals: arsenic, copper, zinc, cadmium, and lead in all samples was carried out by ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry) method. The mean levels (± SE) of arsenic, copper, zinc, cadmium, and lead were found to be 0.037 ± 0.002 mg/kg, 0.070 ± 0.009 mg/kg, 0.143 ± 0.012 mg/kg, 0.005 ± 0.0003 mg/kg, and 0.029 ± 0.002 mg/kg, respectively, in soft drinks. Our data revealed that arsenic, copper, zinc, cadmium, and lead mean levels found in all soft drinks, collected from several regions in Turkey, were within the Turkish Food Codex (TFC) values.

Oxidation changes of different types of vegetable oils were studied during microwave heating. Samples of vegetable oils (rapeseed, sunflower, soybean and corn oil), commercially available at the market in the Czech Republic, were heated in a microwave oven. Parameters as peroxide value, conjugated dienes and trienes levels were determined in oil samples before and after heating in the period from 3 to 30 minutes.

The occurrence of Listeria monocytogenes, Salmonella spp., Bacillus cereus, Staphylococcus spp., Enterococcus spp., and Escherichia coli in raw food materials, food products, and on food contact surfaces after sanitation was investigated during the period of 2005-2006 in three dairy cattle farms (120 samples), one dairy (124 samples), and two meat processing plants (160 samples). A total of 1409 isolates were identified. The epidemiological characterisation and determination of the virulence factors and antimicrobial resistance were performed on selected isolates. The level of bacterial contamination generally decreased during the production process (the contamination of food products was lower than that of raw material). However, the contamination of food contact surfaces was relatively high even after sanitation. Moreover, specific microbiological profiles were found on the inside equipment surfaces in dairy facilities, where genetically closely related multi-resistant strains persisting in biofilm communities may occur as demonstrated for staphylococci. Although the occurrence of potentially significant pathogens was not high, the microorganisms such as L. monocytogenes, Salmonella spp., and shiga-toxin positive E. coli principally contaminated the meat processing plants. B. cereus isolates, among which 76% were positive for diarrhogenic enterotoxin, typically occurred on the inside equipment surfaces and in the heat-treated products.

Some phenolic acids alkyl esters (methyl, ethyl, propyl, butyl and hexyl) and determine their antioxidant and antimicrobial activities were prepared. The antimicrobial activity against the tested microorganisms Escherichia coli DMF 7503, Bacillus cereus DMF 2001, Listeria monocytogenes DMF 5776, Fusarium culmorum DMF 0103, and Saccharomyces cerevisiae DMF 1017 was investigated and expressed by minimum inhibitory concentration (MIC) in the range of 1.2-20mM. The inhibitory activity of phenolic acids butyl esters was found to be higher than that of methyl esters (MIC below 1.25mM). The antioxidant activity of the selected phenolic acids alkyl esters was investigated by Rancimat method. The esters of 3,4-dihydroxyphenolic acids (protocatechuic and caffeic acids) exhibited higher antioxidant activities in comparison with the respective phenolic acids. The highest antioxidant activity was found in the case of caffeic alkyl esters.

Phytic acid has been considered to be an antinutrient due to its ability to bind minerals and proteins, either directly or indirectly, thus changing their solubility, functionality, absorption, and digestibility. In this study, the influence of the flour type (type 500, type 850, and whole meal flour) and three different breadmaking procedures (direct, indirect, and with sourdough addition) on phytic acid was investigated. The results showed that the flour type influenced the phytic acid content. The phytic acid contents of flour type 500, type 850, and whole meal flour was 0.4380, 0.5756, and 0.9460 g/100 g dm, respectively. The dough and bread prepared from flour with a higher phytic acid content also contained higher amount of phytic acid. During fermentation and baking, degradation of phytic acid occurred. Phytic acid was also influenced by pH. Samples of lower pH had a lower phytic acid content. Dough prepared from flour type 500 and type 850 with 10% addition of sourdough had especially low phytic acid contents, and the bread prepared from the respective dough contained no phytic acid at all.

The changes of vitamin C content in relation to Cd, Pb and Zn accumulation in 6 potatoes varieties: very early (Junior, Impala), early (Livera), middle early (Agria), medium-late (Asterix, Desirée) were surveyed in this work. The soil used in pot trial had pseudototal (in soil extract of aqua regia

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, trioxsalen, isopimpinellin) and angular (angelicin, sphondin, isobergapten) furanocoumarins in tested vegetable were determined by validated GC/MS (SIM) method. The detection limits (LODs) obtained by this analytical method were around 0.003 mg/kg.

Enterotoxigenic Bacillus cereus was detected in a variety of meat stuffs (36), ready-to-cook products (5), and swabs (7). The bacterial colonies isolated from PEMBA agar were identified as B. cereus. The 85 isolates were examined for the enterotoxin production using both TECRA-VIA and BCET-RPLA kits (ELISA - 47, RPLA - 38). Thirty two isolates (66%) were positive for enterotoxin using the ELISA test while only 15 isolates (39%) gave positive results in the RPLA test system. In total, 178 (91.8%) and 164 (84%) of the strains isolated in our laboratory (from various foods) were enterotoxigenic as determined using TECRA-VIA and BCET-RPLA, respectively. Parallel enterotoxin positive results obtained using both tests were demonstrated in only 9 isolates from 19 assessed (47.4%). Coincidental negative results from both kits were established for 3 isolates (15.8%) only. The isolates of B.cereus from meat were resistant to cephalothin (57%), clindamycin (14%), oxytetracycline (14%), and erythromycin (7%). The isolates from swabs were resistant to cephalothin (83%), erythromycin (16%), clindamycin (16%) and enrofloxacin (16%).

The aim of the present work is to evaluate the impacts of four different sterilising modes (110°C 100 min, 115°C 32 min, 120°C 10 min, and 125°C 3.2 min - with a constant lethal effect on microorganisms) on some chemical (pH, total and bio-available lysine, and ammonia content), microbiological, and sensory (shade and acceptability) properties of processed cheese depending on the lactose additions (0.0-2.0% w/w). All sterilising modes used were sufficient to inactivate the microorganism groups observed (total number of microorganisms, colony forming units of yeasts and/or moulds, number of spore-forming microorganisms). The falling sterilisation temperature kept for an adequately prolonged period of time caused darkening of the processed cheese and a decline of their acceptability. Consequently, greater losses of lysine and ammonia content increase occurred when the sterilisation temperature decreased. Compared to non-sterilised products, the smallest changes were detected in the cheese treated with temperatures 125°C for 3.2 min, and 120°C for 10 minutes. The decrease of the processed cheese quality was more apparent with the growing lactose concentration.

The changes were studied in microbiological, chemical, and sensory properties of Pacific oysters stored at 10°C, 5°C, and 0°C. Pseudomonas (22%) and Vibrionaceae (20%) species were dominant in raw oysters. The dominant bacteria found in the spoiled samples were Pseudomonas regardless of the storage temperature. During storage, rapid increases in aerobic plate count (APC) values of the samples stored at 10°C and 5°C were observed, while no obvious lag phases were detected. With the samples stored at 0°C, a decrease in APC value during the first 4 days and a lag phase of about 6 days were observed. The APC values of the samples stored at 10°C, 5°C, and 0°C reached the level of 10⁷ CFU/g on day 6, 10, and 18, respectively. All the tested samples stored at different temperatures revealed a slight decrease in pH and a significant increase of total volatile basic nitrogen (TVB-N) during storage. The average TVB-N concentration of about 22.0 mg N/100 g was observed at the end of the shelf-life as determined by APC. Combined with the sensory assessments, the shelf-life of 6-7, 10-11, and 17-18 days for oysters stored at 10°C, 5°C, and 0°C, respectively, was determined.