Fulltext search in archive

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

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

In order to improve the functional properties of soybean protein isolates (SPI), microwave-assisted phosphorylation (MAP) was applied. The result showed that after microwaving at 600 W for 3 min, the phosphorylation level of SPI reached 35.72 mg/g, emulsifying activity and stability were increased 2 times and 1.4 times, respectively, the solubility was increased by 26.0% and the apparent viscosity was decreased by 13.5%. The charge density, content of sulfhydryl groups, and surface hydrophobicity increased significantly. The infra-red spectroscopic analysis indicated PO₄^3- primary and lysine residues for phosphoric acid esterification. The change of amide bond Ι and fluorescence spectrum of variation suggested that the MAP made the secondary and tertiary structures of SPI into a compact conformation. Compared to the regular phosphorylation, the preparation time applied in MAP of SPI was much shorter. These results indicated that MAP can be used as an efficient method to improve the functional properties of SPI.

A chromatographic method is described for assaying fourteen quinolones and fluoroquinolones (pipemidic acid, marbofloxacin, norfloxacin, ciprofloxacin, danofloxacin, lomefloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, nalidixic acid, flumequine, and pyromidic acid) in fish samples. The samples were extracted with m-phosphoric acid/acetonitrile mixture (75:25, v/v), purified, and preconcentrated on ENV + Isolute cartridges. The determination was achieved by liquid chromatography using C₁₈ analytical column. A mobile phase composed of mixtures of methanol-acetonitrile-10mM citrate buffer at pH 4.5, delivered under optimum gradient program, at a flow rate of 1.5 ml/min, allows accomplishing the chromatographic separation in 26 minutes. For the detection were used serial UV-visible diode-array at 280 nm and 254 nm and fluorescence detection at excitation wavelength/emission wavelength: 280/450, 280/495, and 280/405 nm. The detection and quantification limits were between 0.2-9.5and 0.7-32 µg/kg, respectively. The procedure was applied to the analysis of spiked salmon samples at two different concentration levels (50 µg/k and 100 µg/kg). Mean recoveries of fluoroquinolones from the salmon samples ranged from 50% to 102%, depending on the analyte.

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

The cell survival in the digestive tract is one of the main criteria required for the probiotics. The aim of this study was to evaluate the stability of the selected lactobacilli (Lactobacillus acidophilus CCDM 151; L. casei CCDM 198; L. rhamnosus CCDM 150, and L. fermentum ST 68) in conditions simulating those in the gastrointestinal tract as compared to the commercial probiotic strain Lactobacillus casei LAFTI L-26. The growth of lactobacilli decreased both after 2 h and 4 h incubation in MRS media with increasing concentration of bile salt but all lactobacilli had the ability to adapt in the environment of bile salt. Great differences in viability were detected between the isolated cells in the stomach simulating conditions. L. casei LAFTI L-26 and L. acidophilus CCDM 151 were most stable, L. rhamnosus CCDM 150 did not survive under these conditions. Milk revealed a strong protective influence on the viability of all lactobacilli in the stomach simulating conditions. The conditions existing in the small intestine did not influence the cell viability. Differences in autoaggregation were also observed.

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

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

The rheological behaviour of enzyme clarified Lime (Citrus aurontifolia L.) juice was studied as a function of the total soluble solid (TSS) content (7.3-55.7°Brix), corresponding water activity (a_w) (0.985-0.831) at different temperatures (20-80^oC) using co-axial controlled stress rheometer. The rheological parameter shear stress was measured up to the shear rate of 600 s^-1. The investigation showed that the enzyme clarified lime juice and its concentrate behaved like a Newtonian fluid with the viscosity (η) being in the range 3.964 to 50.290 mPa s depending upon the concentration and temperature used. The temperature dependency on the viscosity of lime juice was described by Arrhenius equation (r > 0.99) and the activation energy (E_a) of viscous flow was in the range 4.151 to 26.050 kJ/mol depending upon the total soluble solids content. The effect of total soluble solid content on the flow activation energy was described by exponential type equation (r > 0.98) and that of water activity was described by both the power law and exponential equations (r > 0.99). The effect of total soluble solid content on the viscosity of lime juice followed the second order exponential equation (r > 0.99) at the temperature used. The effect of water activity on the viscosity was described by both the power law and exponential type relationship (r > 0.97). The equations relating to the combined effect of temperature and total soluble solids content/water activity on the viscosity of enzyme clarified lime juice were established.

We investigate the effects of consumption of MRPs from the glucose-lysine model system heated 15°C-90 min on protein digestibility and its utilisation in young (3-week) and adult (12-week) rats. Nitrogen faecal excretion significantly increased after MRP consumption, especially during the third week. Protein digestibility was lower in both age groups studied, but the utilisation was unaffected. Parallelly, the nitrogen retention and its net utilisation for the entire experimental period did not vary. In young rats the faecal nitrogen exceeded the amount of ingested nitrogen coming from MRPs, suggesting that digestibility of undamaged nitrogen was affected. The same action is suspected in adult animals, but the results were not quantitatively conclusive, and therefore the effect should be moderate in this period.

Consumption of minimally processed fruits has been increased lately mainly due to their fresh-like quality characteristics. One of the major alterations that limit the shelf-life of these products is browning caused by polyphenol oxidase (PPO) activity on phenolic compounds. Six yellow-flesh peach cultivars, Spring Lady, Royal Glory, Ruby Rich, Summer Rich, Ryan Sun, and O'Henry, were selected. Peaches were hygienised and then samples were processed in a clean room. Slices were washed in cold tap water, dried, packaged in modified atmosphere, and stored at 4°C during 9 days; physicochemical and other quality parameters were studied. Principal Component Analysis (PCA) and correlation study were carried out in order to evaluate the relation between variables and cultivars. In conclusion, Spring Lady, Royal Glory, and Ruby Rich cultivars were the cultivars that offered the most suitable fruits for fresh-cut processing, mainly due to their low BP and PPO activity.

The utilisation of food consumption databases is widespread and involves for example, the risk assessment, understanding of consumers' food consumption trends, health education, and planning of prevention projects. Harmonisation of national consumption data for international comparison is an important and challenging work. First attempts started in the 70's and have been continuing up to now. The present study gives an overview of the collection methods, types and utilisation of food consumption data, as well of the most important phases of the international harmonisation work. As this study shows, it is crucial to harmonise the surveys parameters like the time of the data collection, method, number of participants, and number of the analysed days for an internationally comparable consumption database. From this point of view, the efforts of the EU menu project are promising.

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

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

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

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

The manipulation of grape yield is widely practised to improve grape and wine quality. Merlot and Cabernet Sauvignon vines in the Zagreb vineyard hills, north-western Croatia, were subjected to three crop removal treatments [cluster thinning (CT), berry thinning (BT), CT+BT, and untreated control] in a randomised block design experiment. CT and CT+BT treatments reduced the grape yield but increased the mean cluster weight compared to control vines. BT alone had a little effect on the yield components. Control grapes generally had the lowest soluble solids (°Oe) and highest titratable acidity (g/l). In most cases, control wines had the lowest total phenols, flavan-3-ols, and anthocyanin concentrations, while CT+BT treatment had the highest ones followed by CT treatment. It was concluded that CT+BT produced wines with generally increased total phenols, flavan-3-ols, and anthocyanins, as well as many individual phenolic compounds. Thus, grape yield per vine seems to be strongly connected with the grape and wine compositions. The final cost-effectiveness of this canopy interventions still remains questionable.

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

We investigated the changes in omega 3 enriched carp fillets caused by pan frying. The investigated characteristics were fat uptake, fatty acid (FA) composition, and oxidation. Four different fats were used and fillets were fried plain or battered. The fillet fat content increased during frying and FA composition in the fillets reflected the composition of the frying fat. Frying with sunflower oil negatively influenced the nutritional value by decreasing the n-3/n-6 ratio in the fillets. Frying with rapeseed oil preserved the favourable n-3/n-6 ratio without increasing the saturated fatty acids (SFA). Frying with lard and butter preserved the n-3/n-6 ratio but increased the SFA content. No increased oxidation occurred with the use of rapeseed oil. We concluded that using rapeseed oil for fish seemed to preserve the nutritionally valuable composition best.

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

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

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

3-alkyl-2-methoxypyrazines (MPs) represent an important and potent class of odor-active compounds associated with wine quality. 30 ng/l each of 3-isobutyl-2-methoxypyrazine, 3-isopropyl-2-methoxypyrazine and 3-secbutyl-2-methoxypyrazine were added to a Riesling and Cabernet Franc wine and monitored with HS-SPME-GC-MS over 18 months to investigate the effects of various closure and packaging options as well as light and storage temperature on MPs. Other impact odorants were monitored using SPE-GC-FID. Changes in MP concentrations during bottle aging varied with closure/packaging option, with the greatest decrease evident in Tetrapak® cartons. We observed similar changes in other impact odorants to previous studies, with synthetic corks displaying an increased capacity for sorption compared to natural corks and screwcaps. MPs did not vary consistently over time with light or temperature conditions. Acetate esters decreased, regardless of light or temperature conditions, while phenethyl acetate and isoamyl acetate decreased at a greater rate in ambient temperature conditions compared with 12°C. Free and bound SO₂ retention was higher in light-excluded conditions and influenced by bottle hue.

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

Cereals are generally known to have a positive influence on the general state of the human organism. The attention of the nutritional experts is paid especially to oats and barley. Besides their accessibility, these cereals are interesting due to their relatively high contents of soluble non-starch polysaccharides (fibrous material), out of which β-glucans have a dominant position from the aspect of health benefit. This paper presents a brief review of the latest knowledge on the positive effects of β-glucans on the consumer's health. The structure, occurrence, sources, and positive physiological effects of β-glucans on the cardiovascular system but also their antibacterial, antitumoral, immunomodulant, and radioprotective properties are mentioned. In the paper are given examples of β-glucans exploitation as functional ingredients in food, cosmetic, and pharmaceutical industries and as food additives on the basis of cereal fibres and cereal β-glucans.

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

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

The presented paper covers the preliminary studies on microwave inactivation of honey enzymes described as diastase number (DN). All the investigations were done on commercially available honey from Polish local market. Microwave processes were compared to the conventional ones. In the case of conventional conditions, the constant rate of diastase enzyme inactivation was estimated using the first order kinetics. In the case of microwave heated samples, it was impossible to establish the rate constant; however, the investigation proved the suitability of such kind of processing for short-term thermal treatment of honey.