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Results 4441 to 4470 of 5716:

Microwave treatment and drying of germinated pea

M. Skulinová, P. Kadlec, J. Kaasová, J. Dostálová, M. Zátopková, V. Hosnedl, J. Hrachovinová

Czech J. Food Sci., 2002, 20(1):23-30 | DOI: 10.17221/3505-CJFS

It is possible to use germination of grain legumes as the most effective way of decreasing a high content of a-galactooligosaccharides which undesirably affect the nutritive value and acceptability of legumes. Content of a-galactooligosaccharides was reduced to 38% (Gotik cultivar) and to 45% (Grana cultivar) of the original value after 2 days of germination. The aim of further processing was to dry germinated pea to final moisture content 12-14%. Very interesting results were obtained when microwave heating was used as a preliminary treatment before hot air drying. Microwave treatment reduces the time of drying. The contents of soluble carbohydrates (sucrose, raffinose, stachyose and verbascose), proteins and trypsin inhibitor activity were determined as criteria of microwave heating effects on the chemical composition of germinated pea. Germinated pea was used for the preparation of pea soups and these pea dishes were sensory evaluated.

Testing of scanner and colour-meter for observation of changes during storage of two selected foods

P. Novotná, K. Kýhos, A. Landfeld, J. Strohalm, M. Houška

Czech J. Food Sci., 2002, 20(5):203-208 | DOI: 10.17221/3532-CJFS

The test with colour and aroma of Kladno cooked pork loin stored in refrigerator and at the room temperature correspond with its spoilage was done. No change of the L* co-ordinate has been observed during the storage. A strong decrease of a* co-ordinate for red colour after 1-day storage has taken place for samples stored in a room (approx. 25°C). Conversely, an increase of b* coordinate for yellow colour has been observed after 1-day storage. A change of the cooked pork loin aroma has also been noticed after 1-day storage using the sensory observation. Further, the possibility has been tested of using a portable scanner for the determination of banana colour changes. It has been found that the optimal storage temperature from the peel colour point of view is 14°C; it is in accordance with recommendations in literature.

The effect of phenological stage and season on nutritive value, chemical composition and nutrient digestibility of lucerne (Medicago sativa L.) green forage in the alimentary tract of cattle

B. Niwińska, J.A. Strzetelski, J. Kowalczyk, F. Borowiec, P. Domański

Czech J. Anim. Sci., 2005, 50(11):511-518 | DOI: 10.17221/4256-CJAS

Green forage of fourteen lucerne varieties grown at four Experimental Stations of the Research Centre for Cultivar Testing in Słupia Wielka was harvested in these stages: the first growth in the budding stage (cut I), re-growths in the pre-bloom stage of maturity (cut II) 35 days after the first cut, and the next cut, 42 days later (cut III). Three bulls equipped with rumen and duodenal cannulas were used to study rumen degradability by the nylon bag technique and intestinal digestibility by the mobile bag method. The nutritive value of lucerne green forage was estimated according to IZ-INRA (2001) feed evaluation system. The composition of the lucerne cuts differed in DM content (P < 0.01); the highest was found in cut III (226.9 g/kg), the lowest in cut II (182.0 g/kg).The crude protein content (CP) in DM of cuts I and II was similar (P > 0.05) but lower in cut III (P < 0.05). Cut II contained the highest (P < 0.05) levels of crude fibre, neutral detergent fibre (NDF), acid detergent fibre (ADF), cellulose (CE), and acid detergent lignin (ADL), and the lowest of non-structural carbohydrates (NFC) and soluble in neutral detergent cell content (CC), (P < 0.01). The differences between cut I and III in the contents of these components were not significant (P > 0.05). The highest DM digestibility in the total alimentary tract was found for cut I (P < 0.05). The DM of cuts II and III was digested at a similar rate (P > 0.05). There were no significant differences between the cuts in effective degradability, digestibility in the small intestine of the fraction not digested in the forestomachs and total digestibility of CP, CF, NDF, ADF, hemicellulose and cellulose (P > 0.05). The digestion of rumen undegraded CP in the post-rumen part of the alimentary tract was lower compared with the digestion of essential amino acids (81% and 98%; respectively). The first cut harvested in the spring in the budding stage contained about 5% more PDIA and PDIN, but 7% less LFU compared with both cuts of regrowth (cuts II and III) which contained on average: 58 g PDIA; 123 g PDIN and 0.93 kg LFU. All the cuts contained similar levels of PDIE, UFL per kg of DM (106 and 0.76 g, respectively).

Influence of dietary selenium level on the concentration of conjugated linoleic acid isomers, other fatty acids and amino acids in the liver and femoral muscles of rats

M. Czauderna, J. Kowalczyk, K.A. Krajewska

Czech J. Anim. Sci., 2011, 56(2):81-94 | DOI: 10.17221/55/2010-CJAS

The purpose of the present study was to determine the influence of diets containing conjugated linoleic acid isomers (CLAmix) with or without low (LSe) or high (HSe) concentration of selenised yeast (SeY) on body weight gain (BWG), feed conversion efficiency (FCE), and concentrations of CLA isomers and other fatty acids (FA) in the liver and femoral muscle of rats. The investigation was performed on 48 female rats (Wistar, Hsd Brl Han: WIST), aged 8 weeks with an initial body weight of 195.7 ± 0.8 g. After one week of submaintenance feeding, for 6 weeks the rats were fed ad libitum the Labofeed H diet supplemented with 1.5% CLAmix with or without low (0.2 μg Se/g diet) or high (0.5 μg Se/g diet) concentration of Se as SeY. The diet enriched with LSe or HSe elevated the BWG of rats compared with the control group, while the LSe diet resulted in the most efficient increase in BWG. The diet containing CLAmix, irrespective of the presence of SeY, stimulated the accumulation of Se in the liver and muscles in comparison with the diet enriched with SeY. The addition of SeY to the diet enriched with CLAmix stimulated the accumulation of cis9trans11 (c9t11), t10c12 and cc isomers of CLA in the liver. The diet containing CLAmix and LSe most efficiently increased the concentration of these CLA isomers in muscles. The diets enriched with SeY increased the concentration of essential, endogenous and total amino acids (AA) in the liver, whereas the diets enriched with SeY or CLAmix reduced the concentration of these AA in muscles. The diets enriched with CLAmix and/or SeY decreased the Δ9-desaturase index in the liver and muscles compared with the control group. These diets increased Δ4-, Δ5- and Δ6-desaturase indexes in muscles, but significantly reduced the elongase index compared with the control group. Our study shows that dietary CLAmix increased the concentration of C14:0, C18:0 and the sum of saturated FA (SFA) in the liver, whereas the diets enriched with SeY, irrespective of the presence of CLAmix, slightly reduced the concentration of C14:0, C18:0, and SFA in muscles compared with the control group. The diets containing SeY and/or CLAmix increased the accumulation of arachidonic acid (ArA), linolenic acid (αLNA) and c4c7c10c13c16c19C22:6 in the liver compared with the control rats. Negative effects of dietary SeY and/or CLAmix on the accumulation of αLNA, c5c8c11c14c17C20:5, c7c10c13c16c19C22:5, c4c7c10c13c16c19C22:6, linoleic acid, ArA and c8c11c14C20:3 in muscles were found out. The CLAmix diet increased the Δ4-, Δ5-desaturase and elongase indexes in the liver. It also increased the Δ4-, Δ5- and Δ6-desaturase indexes in muscles, but significantly reduced the elongase index compared with the control group. The finding that the diet with CLAmix and HSe fed to rats decreased total FA and most efficiently increased the content of Se and essential AA in muscles is valuable

Optical isomers of chloropropanediols: mechanisms of their formation and decomposition in protein hydrolysates

J. Velíšek, M. Doležal, C. Crews, T. Dvořák

Czech J. Food Sci., 2002, 20(5):161-170 | DOI: 10.17221/3527-CJFS

Protein hydrolysates produced by hydrochloric acid hydrolysis were analysed for 3-chloropropane-1,2-diol and its enantiomers. It was found that (R)-3-chloropropane-1,2-diol and (S)-3-chloropropane-1,2-diol were present in the hydrolysates in equimolar concentrations. Model experiments with glycerol, triolein and soy lecithin heated with hydrochloric acid in solution showed that these materials were precursors of 3-chloropropane-1,2-diol and 2-chloropropane-1,3-diol and, as expected, yielded racemic 3-chloropropane-1,2-diol. Yields of 3-chloropropane-1,2-diols decreased in the order triolein > lecithin > glycerol. The mechanisms of 3-chloropropane-1,2-diol enantiomers formation during the production of protein hydrolysates are presented and discussed as well as the reaction pathways of their decomposition in alkaline media via the corresponding intermediates, (R)- and (S)-glycidol, respectively. Both epoxides are hydrolysed to glycerol and form a variety of products with hydrolysate constituents.

Antioxidant activity of rye caryopses and embryos extracts

M. Karamać, R. Amarowicz, S. Weidner, S. Abe, F. Shahidi

Czech J. Food Sci., 2002, 20(6):209-214 | DOI: 10.17221/3533-CJFS

Phenolic compounds were extracted with 80% methanol from caryopses and embryos of rye (cv. Dańkowskie Złote and Amilo). In all extracts, reducing power, scavenging effect on DPPH radical, and antioxidant activity in a β-carotene-linoleate model system were examined. The highest content of total phenolic compounds was noted in the extract from caryopses of Amilo (7.93 mg/g of extract). UV spectra of all extracts were characterised by maxima originated from phenolic acids (320, 326 and 328 nm), and by maxima at shorter wavelengths (272 and 274 nm) attributed to other phenolic compounds. All extracts showed a good antioxidant activity in a β-carotene-linoleate model system. This activity was similar to that reported before in leguminous seeds extracts. The antioxidant activities of the extracts from the caryopses of Dańkowskie Złote and the embryos of both cultivars were very similar, especially during the second part of the incubation period. The extract of Amilo embryos showed a slightly weaker antioxidative effect. The weak antiradical effects in the experiments with DPPH radical and a weak reducing power were characteristic for all the extracts investigated.

The conformability of two equations for bacterial growth in pork

M. Miyahara, T. Matsumoto, H. Sakurai, P. Pipek

Czech J. Food Sci., 2002, 20(2):69-73 | DOI: 10.17221/3512-CJFS

Pork is now distributed as cut meat, which increases the chance of contamination with bacteria. The rate of bacterial growth can be expressed by an exponential function. In order to find how the number of contaminating bacteria increases, we compared two functional equations for a growth curve. They are logistic: Yt = K (1 + m e-at) (1) and Gompertz: log Yt = log K + (log a)bt (2) equations (where Yt = the number of bacteria at the time t in min, m and a = coefficient, e = natural logarithm, K maximum number of bacteria). 90 ml of physiological salt solution was added to 10 g of pork. It was homogenized for 3 min, then incubated at 35°C for 13 hrs. The number of bacteria was counted every hour. We found from these data that the above two equations can be expressed as follows: Yt = 23 535 (1 + 16269 e-1.1608t) and log Yt = 8.9940 + (-3.1124) × 0.7839t. The theoretical and actual values matched well in equation (1), and the number of bacteria can be predicted accurately using this equation at a given time after incubation. The theoretical and actual values did not match well in equation (2) and its accuracy to predict the number of bacteria was very low except the initial number of bacteria was high.

Comparison of some commercial pectic enzyme preparations applicable in wine technology

D. Čapounová, M. Drdák

Czech J. Food Sci., 2002, 20(4):131-134 | DOI: 10.17221/3523-CJFS

The preparations of pectic enzymes are used for a more efficient extraction of desirable red grape pigments and other phenol compounds which are bound in plant cells and can be faster released by the action of pectic enzymes. Moreover, they shorten the time of maceration, settling, and filtration. The results of our experiments gives a comparison of the efficiency of preparations applicable in wine technology. The best preparation was Trenolin Rot followed by Vinozym G that could shorten the time of prefermentation to about 3 days thanks to a more intensive extraction of red grape pigments. By using the enzyme preparations Gammapect AWP and Ovopres, the time of filtration was ten times shorter. Compared to the control sample, the speed of desliming was threefold and twofold faster, respectively, for Gammapect AWP and Gammapect W2L.

Use of transglutaminase for improvement of quality of pastry produced by frozen-dough technology

B. Hozová, J. Jančovičová, L. Dodok, V. Buchtová, L. Staruch

Czech J. Food Sci., 2002, 20(6):215-222 | DOI: 10.17221/3534-CJFS

The improving effect on the quality of final products has been studied of the enzyme transglutaminase added in two concentrations, i.e. 4.5 mg or 7.5 mg/300 g of flour destined for the preparation of pastry dough. Changes of the sensory (sensory profile), nutritional (the contents of amino acids, especially that of lysine), and microbiological quality (total count, yeasts, moulds) were investigated as well as those of aw and pH values of the pastry produced from the freezer-stored dough (-18 ± 2°C). It has been found that the sensory quality is favourably affected by the addition of transglutaminase (TGM) in the amount of 4.5 mg/300 g of flour and on the other hand that the protective effect on lysine increases if the applied TGM concentration is higher (7.5 mg per 300 g of flour). The microbiological quality, the pH and aw values of dough, and the products have satisfied the criteria for the sanitary and hygienic requirements.

Effect of temperature and enzyme/substrate ratio on the hydrolysis of pea protein isolates by trypsin

M. Karamać, R. Amarowicz, H. Kostyra

Czech J. Food Sci., 2002, 20(1):1-6 | DOI: 10.17221/3502-CJFS

Two pea protein isolates, Pisane and Propulse, were hydrolysed by trypsin. The degree of hydrolysis (DH) was computed using a pH-stat method. Enzymatic treatment of the pea protein isolates was conducted at four different temperatures, namely 35, 40, 45 and 50°C. The relationship between DH and E/S ratio was studied at 50°C and at four different E/S ratios; these were 5, 15, 25, 35 mAU/g (AU - Anson unit). For Pisane the highest value of the final DH (10.4%) was obtained at 45°C, whereas for Propulse the optimal temperature was 50°C and a DH value of 13.2% was attained. In the case of Pisane, the highest DH (11.5%) was recorded if the enzyme/substrate ratio was 35 mAU/g whereas for Propulse, the highest DH (13.2%) was observed at an E/S ratio of 15 mAU / g.

Proximate neutral lipid composition of niger (Guizotia abyssinica Cass.) seed

Mohamed Fawzy Ramadan, Jörg-Thomas Mörsel

Czech J. Food Sci., 2002, 20(3):98-104 | DOI: 10.17221/3518-CJFS

Niger (Guizotia abyssinica Cass.) seed was extracted with hexane (H) and chloroform/methanol (CM) (2:1, v/v) to determine the effect of the solvent on the amount and composition of the recovered lipid. The amount of the total lipid (TL) extracted with H was 29.6% of the seed weight, while that extracted with CM was 49.9%. Column and thin-layer chromatographic procedures on Silica Gel were performed to fractionate the main neutral lipid (NL) subclasses. Fatty acid composition of the NL subclasses, triacylglycerol (TAG) molecular species, and sterol (ST) content were estimated. The NL amount was found to be higher (97% of TL) in the H extract than in the CM extract (93% of TL). TAG appeared to be the predominant NL subclass (89.7-91.9% of total NL). Linoleic acid (C18:2n-6) was the main fatty acid followed by oleic acid (C18:1n-9) as the second main unsaturated fatty acid, while palmitic acid (C16:0) was the major saturated fatty acid. With high temperature gas-liquid chromatography using a flame ionization detector (HTGLC/FID) and H2 as the carrier gas, the actual TAG molecular species according to their carbon numbers were separated. TAG of even carbon numbers 16 and 18 were contained in six TAG molecular species. The major peaks occured at C54:6, and C54:3 corresponding to trilinolein and triolein. Furthermore, TAG molecular specie, expected to contain two molecules of linoleic acid (C54:5), was detected in a high level. Phytosterol pattern was determined without derivatization in the unsaponifiable fractions by HTGLC/FID. ST profile was characterized by a high total amount accounting for 4.22 g/kg of total H extract, and 4.00 g/kg of total CM extract. b-Sitosterol (2.035-1.929 g/kg TL) was the main component in both extracts. The major ST found were, in order of decreasing prevalence, b-sitosterol > campesterol > stigmasterol > D5-ave-nasterol > D7-avenasterol > lanosterol.

Chemical and biochemical changes during microwave treatment of wheat

J. Kaasová, B. Hubáčková, P. Kadlec, J. Příhoda, Z. Bubník

Czech J. Food Sci., 2002, 20(2):74-78 | DOI: 10.17221/3513-CJFS

The effect of microwave (MW) heating on the changes in wet gluten content, Gluten Index, Falling Number and amylographic characteristics was studied in sprouted wheat grain. Different moistures of wheat in two ranges of 10-11% and 15-17% and two end temperatures of MW heated samples (60 and 80°C) were applied to wheat samples. Falling Number and Gluten Index increased with increasing absorbed energy during MW heating, whereas gluten content decreased. Amylographic maximum increased due to a-amylase inactivation progressively with increasing absorbed energy as well. The greatest relative changes occurred when the end temperature of MW heated samples 80°C and moisture 15% were used. An improvement effect on the baking quality of sprouted wheat was found due to an increase in amylographic maximum with higher energy doses and higher end temperatures of MW heated samples. It was a consequence of Falling Number increase and Gluten Index increase with lower energy doses. The negative effect of higher energy doses was proved in a decrease in wet gluten content.

Beta-galactosidase activity in psychrotrophic microorganisms and their potential use in food industry

P. Karasová, V. Spiwok, Š. Malá, B. Králová, N.J. Russell

Czech J. Food Sci., 2002, 20(2):43-47 | DOI: 10.17221/3508-CJFS

Twenty-one psychrotrophic resp. psychrophilic bacterial strains were screened for presence of b-galactosidase activity which showed 8 of them. b-Galactosidase activity of these strains was determined for 2 substrates - synthetic substrate (ONPG) and lactose - and also temperature profile of this enzyme was measured. b-Galactosidase from Arthrobacter sp. C2-2 not only proved the typical properties of cold-active enzyme, but it also preferred lactose as a substrate. Therefore, it was chosen for further isolation and purification and was found that it contains two b-galactosidase isoenzymes. One of them had strong preference for lactose and was able to catalyse transglycosylation reactions at low temperature. It has, thus, potential use in food technology.

Essential oil composition of Ocimum basilicum L. and Ocimum minimum L. in Turkey

Musa Özcan, Jean-Clause Chalchat

Czech J. Food Sci., 2002, 20(6):223-228 | DOI: 10.17221/3536-CJFS

The constituents of essential oils isolated by hydrodistillation of the overground parts of Ocimum basilicum L. and Ocimum minimum L. from Turkey were examined by GC-MS. A total of 49 and 41 components, respectively, were identified accounting for 88.1% and 74.4% of the oils of O. basilicum and O. minimum, respectively. The oil of O. basilicum contained, as main components, methyl eugenol (78.02%), α-cubebene (6.17%), nerol (0.83%) and ε-muurolene (0.74%). Major compounds in the volatile oil of O. minimum were geranyl acetate (69.48%), terpinen-4-ol (2.35%) and octan-3-yl-acetate (0.72%). The essential oil of O. basilicum was characterised by its high content of methyl eugenol (78.02%), whereas the most important essential oil constituent of O. minimum was geranyl acetate (69.48%).

Enzymatic hydrolysis of defatted soy flour by three different proteases and their effect on the functional properties of resulting protein hydrolysates

M. Hrčková, M. Rusňáková, J. Zemanovič

Czech J. Food Sci., 2002, 20(1):7-14 | DOI: 10.17221/3503-CJFS

Commercial defatted soy flour (DSF) was dispersed in distilled water at pH 7 to prepare 5% aqueous dispersion. Soy protein hydrolysates (SPH) were obtained by enzymatic hydrolysis of the DSF using three different proteases (Flavourzyme 1000 L, No-vozym FM 2.0 L and Alcalase 2.4 L FG). The highest degree of hydrolysis (DH 39.5) was observed in the presence of protease Flavourzyme. SPH were used for measuring functional properties (foaming stability, gelation). Treatment with Flavourzyme improved foaming of proteins of DSF. Foaming stability was low in the presence of Novozym. Proteases treated DSF showed good gelation properties, mainly in the case of treatment with Flavourzyme. SDS-PAGE analysis showed that after enzyme ad-dition to the 5% aqueous dispersion of DSF each enzyme degraded both b-conglycinin and glycinin. In general, the basic polypeptide from glycinin showed the highest resistance to proteolytic activity. The most abundant free amino acids in the hydrolysates were histidine (30%), leucine (24%) and tyrosine (19%) in the case of the treatment with proteases Alcalase and Novozym, and arginine (22.1%), leucine (10.6%) and phenylalanine (12.9%) in the case of the treatment with Flavourzyme.

Lipid oxidation and quality parameters of sausages marketed locally in the town of Săo Paulo (Brazil)

C.K.B. Ferrari, E.A.F.S. Torres

Czech J. Food Sci., 2002, 20(4):144-150 | DOI: 10.17221/3525-CJFS

Lipid oxidation constitutes one of the most important causes of the chemical deterioration of foods, especially meats. Many harmful effects on human health are associated with lipid oxidation. During a period of six weeks, samples were bought at random on city hall food markets (CHFMs) and were analysed for lipid oxidation (TBARS-test) and some quality factors - redox potential (Eh), pH and water activity (aw). The mean of Eh was X ± σn-1 = 39.03 ± 26.30 mV, ranging from -86.00 to 92.00 mV. pH mean value was X ± σn-1 = 5.97 ± 0.27, ranging from 5.08 to 6.48. Comparing the CHFMs, no statistically significant differences were observed between them in respect to pH, Eh, and aw values. TBARS mean value was X ± σn-1 = 0.44 ± 0.23 mg/kg, ranging from 0.38 ± 0.19 mg/kg (CHFM-6) to 0.58 ± 0.31 mg/kg (CHFM-2), with extreme values of 0.22 mg/kg and 1.08 mg/kg. No statistically significant correlations between TBA test values and all tested variables were detected. According to the sensorial analysis criteria of Greene and Cumuze (1981), 16.67% of sausage samples could be rejected and 11.11% revealed critical TBARS values.

Linear and linear-threshold model for genetic parameters for SEUROP carcass traits in Czech beef cattle

Z. Veselá, L. Vostrý, P. Šafus

Czech J. Anim. Sci., 2011, 56(9):414-426 | DOI: 10.17221/1292-CJAS

The objective of this study was to estimate genetic parameters for the results of classifying of carcass traits by the SEUROP method in beef cattle in the Czech Republic using linear and linear-threshold models. Genetic parameters were calculated and evaluated in a set of 4276 animals of eleven beef breeds and crosses with dairy and dual-purpose breeds (Aberdeen Angus - 1376, Hereford - 994, Simmental - 651, Charolais - 524, Piemontese - 185, Galloway - 162, Blonde d'Aquitaine - 147, Limousine - 106, Highland - 53, Gasconne - 44, Belgian Blue - 34) in 2005-2008. Aberdeen Angus, Hereford, Charolais and beef Simmental were the most numerous breeds. Fixed effect of a classifier, fixed regression on age at slaughter by means of Legendre polynomial of the second degree separately for the each breed and sex and fixed regression on heterosis coefficient were included in a model equation. Genetic parameters were estimated by a multi-trait animal model using a linear model and a linear-threshold model in which carcass weight (CW) was considered as the linear trait and carcass conformation (CC) and carcass fatness (CF) grading as threshold traits. The heritability coefficient for CW differed only moderately according to the method of the genetic parameter estimation (0.295 in linear model and 0.306 in linear-threshold model). The heritability coefficient for CC was 0.187 in linear model and 0.237 in linear-threshold model. The heritability coefficient for CF grading was 0.089 in linear model and 0.146 in linear-threshold model. Genetic correlation between CW and CC was high (0.823 in linear model and 0.959 in linear-threshold model), the correlation between CW and CF was intermediate (0.332 and 0.328, respectively) and it was low between CF and CC (0.071 and 0.053). If CW was included in the model equation as fixed regression using Legendre polynomial, lower heritability coefficients for CC (0.077 and 0.078) and CF (0.086 and 0.123) were calculated and the correlation between CC and CF was negative (-0.430 and -0.429).

Inhibition of Aspergillus niger DMF 0801 by monoacylglycerols prepared from coconut oil

Z. Řiháková, V. Filip, M. Plocková, J. Šmidrkal, R. Červenková

Czech J. Food Sci., 2002, 20(2):48-52 | DOI: 10.17221/3509-CJFS

The objectives of the present study were to test the antifungal properties (inhibition of radial growth, inhibition of the mould spore germination) of lauroylglycerol and mixtures of monoacylglycerols synthesised from coconut oil (MIX-I and MIX-II) against Aspergillus niger DMF 0801. The content of monoacylglycerols in lauroylglycerol, MIX-I and MIX-II was 99.9% (w/w), 97.7% (w/w) and 75,1% (w/w), respectively. The content of 1-lauroylglycerol in MIX-I and MIX-II was calculated from the content of lauric acid and content of monoacylglycerols. The inhibition of the radial growth of Aspergillus niger DMF 0801 by lauroylglycerol was stronger than that caused by MIX-I and MIX-II. The inhibition effect of spore germination caused by lauroylglycerol and MIX-I was nearly the same. The inhibition of spore germination increased with increasing content of monoacylglycerol and also with increasing 1-lauroylglycerol content in monoacylglycerols. The level of spore germination inhibition was related to the purity of tested substances. The results of this study indicate that monoacylglycerols made from coconut oil have antifungal activity.

Effect of defatted soybean flour on the flavour of extruded mixtures with wheat flour

J. Pokorný, A. Farouk Mansour, F. Pudil, V. Janda

Czech J. Food Sci., 2002, 20(6):229-236 | DOI: 10.17221/3535-CJFS

Mixtures of wheat semolina, 5% glucose and 0-30% defatted soybean flour were used for the preparation of extruded samples using a pilot plant single screw extruder, maximum temperature being 140°C. The browning reactions were only moderate, the intensities of the trichromatic a* coordinate increased, and some changes were observed in chroma and the odour difference ΔE*. The sensory acceptability improved by increasing the content of soybean flour, the odour intensity increased, and some changes were observed in the sensory profile. Volatile substances were isolated using a SPME procedure, and the volatiles were separated using a Fisons GLC 8000 apparatus equipped with a mass spectrometer. Among the flavour active volatiles, pyrazines were the most prominent class of compounds, especially methyl and ethyl substituted derivatives. Pyrrole and furan substituted pyrazines were found only in small amounts because of the low extrusion temperature. Other furan and pyrrole derivatives had a lesser effect on flavour because of their relatively low amounts. Aldehydes, fatty acids, ketones, and other aliphatic derivatives contributed only a little to the resulting flavour. Compared to the mixtures of semolina and glucose only, the additions of defatted soybean flour moderately increased the number of substituted pyrazines detected in the extruded mixtures but increased substantially the pyrazine fraction in the total peak area. Among furan derivatives, 2-furancarboxaldehyde, 2-furanmethanol and 5-methyl-2-furyl alcohol belonged to the most prominent derivatives. Among other compounds, acetic acid, butyrolactone and maltol should be mentioned.

Phenolic compounds of seed coats of white and coloured varieties of pea (Pisum sativum L.) and their total antioxidant activity

A. Troszyńska, E. Ciska

Czech J. Food Sci., 2002, 20(1):15-22 | DOI: 10.17221/3504-CJFS

The purpose of this study was to compare the composition and contents of phenolic acids and condensed tannin in the seed coats of white and coloured varieties of pea and to examine the antioxidant properties of methanol and acetone extracts containing these phenolic compounds. The contents of phenolic acids were quantified by the HPLC analysis. The sum of free phenolic acids, those liberated from soluble esters and those liberated from soluble glycosides, was higher for coloured seed coat (78.53 g per g dry matter) than for the white seed coat (17.17 g/g dry matter). Protocatechuic, gentisic and vanillic acids were found dominant in the coloured seed coat, while ferulic and coumaric acids in the white seed coat. The content of condensed tannins was 1560 mg of catechin equivalent/100 g of coloured seed coat as determined by a vanillin assay. No condensed tannins were detected in the white seed coat. The antioxidant activity of extracts was measured by the oxidation of phosphatidylcholine to hydroxyperoxidephosphatidyl choline in the liposome system. Strong antioxidant properties were observed in a crude tannin extract from the coloured seed coat. These properties were slightly changed after the seed coat was cooked in water for 30, 60 and 90 min.

Residence time distribution during egg yolk pasteurisation

A. Landfeld, R. Žitný, M. Houška, K. Kýhos, P. Novotná

Czech J. Food Sci., 2002, 20(5):193-201 | DOI: 10.17221/3531-CJFS

This work describes the determination of the average residence times during egg yolk - and whole liquid eggs pasteurisation in an industrial pasteurisation equipment (plate pasteuriser + tube holder). For the detection of the impulse the conductivity method was used. Conductivity was then monitored using the bridge method. In the system, the total of 3 probes were placed. To mark the particles of the flowing product, salted yolk with the content of salt of 1.3 or 1.8% was used. In addition, rheological properties of pasteurised yolk were determined at the temperatures of 5, 25, 45, and 65°C. Based on the geometry of the channels in the individual sections of the pasteurisation equipment, the character of the flow was estimated using the Re criterion and was found to be laminar in all parts of the system. The work includes the comparison of the average residence times obtained by (a) the method of volumes, (b) the analysis of the conductivity response, (c) the estimate made by using the TUPLEX software, and (d) the estimate of the peaks of the conductivity response.

Sustainable land management by restoration of short water cycles and preventionof irreversible matter losses from topsoils

W. Ripl, M. Eiseltová

Plant Soil Environ., 2009, 55(9):404-410 | DOI: 10.17221/133/2009-PSE

Sustainable land management requires that water and matter (nutrients and base cations) are efficiently recycled within ecosystems so that irreversible losses of matter from topsoils are minimised. Matter losses are connected to water flow. The division of water into evapotranspiration that is loss-free, and seepage to groundwater or surface water flow that both carry material losses, is decisive in determining total losses of dissolved matter in a given catchment. Investigations of areal matter losses confirmed the instrumental role of vegetation cover. Areal matter losses measured in agricultural catchments in Germany were on average between 1-1.5 tons of dissolved matter per ha per year, i.e. some 50 to 100 times higher than those from unmanaged land in a virgin forest. Such high losses continuously reduce soil fertility and can hardly be compensated by fertilisation. Some suggestions on how to achieve sustainable management of agricultural land and maintain high soil fertility are presented - the priority is to close water and matter cycles through the incorporation of more natural vegetation cover into our landscapes and to restore the energy-dissipative properties of ecosystems.

Development of species composition in long term simulations with an individual-tree growth simulator

M. Huber, H. Sterba

J. For. Sci., 2009, 55(5):194-200 | DOI: 10.17221/14/2009-JFS

The spruce-fir-beech dominated forest stands in Litschau in the Austrian part of the Bohemian Massif were converted by former forest management practices into pure Norway spruce stands and are now discussed to be reconverted into the potential natural vegetation type. The targeted potential natural vegetation type is usually defined by experts in vegetation sciences. Because meanwhile individual-tree growth simulators are a well acknowledged tool for predicting future forest stand development, in this study we investigate if PROGNAUS can also be used to predict the redevelopment of managed forest ecosystems into natural forest ecosystems regarding species composition. The development of 23 stands in Litschau has been simulated over 1,000 years under the "no-management" option. Generally, the simulated species distribution agrees quite well with the expectations of the potential natural vegetation type. However, the predicted amounts of silver fir and maple species are lower than expected, which probably is due to browsing and management effects represented in the parameterization data for PROGNAUS.

Influence of pulverized limestone and amphibolite mixture on the growth performance of Alnus incana (L.) Moench plantation on an acidified mountain site

I. Kuneš, V. Balcar, T. Benešová, M. Baláš, J. Zadina, D. Zahradník, J. Vítámvás, D. Kacálek, O. Špulák, M. Jakl, J. Jaklová Dytrtová, V. Podrázský

J. For. Sci., 2009, 55(10):469-476 | DOI: 10.17221/35/2009-JFS

A young speckled alder (Alnus incana [L.] Moench) stand was planted on a tract clear-felled due to air pollution and located on a summit plateau of the Jizerské hory Mts. (Central Europe, Czech Republic) at an altitude of 950 m a.s.l. The aim of the experiment was to test the suitability of Alnus incana to form preparatory stands covering the site and thus enabling the reintroduction of more sensitive target species. A potential of Alnus incana to respond to slow-release fertilizing was tested as well. The control treatment showed sufficient growth dynamics, nevertheless, the fertilization significantly promoted the growth (documented by height, height increment and stem-base diameter). If some limitations of alder such as high light requirements are respected, the speckled alder can be recommended as a suitable species for preparatory stands even in the 7th and 8th altitudinal (vegetation) zones, especially when fertilized.

The Transfer of Heavy Metals from Contaminated Soils into Agricultural Plants in High Tatras Region

T. Tóth, J. Tomáš, P. Lazor, D. Bajčan, K. Jomová

Czech J. Food Sci., 2009, 27(10):S390-S393 | DOI: 10.17221/600-CJFS

The problems of soil hygiene and contents of the following heavy metals: cadmium, cobalt and nickel in the productive parts of plants in the location of Agricultural Cooperative Štrba in Poprad County were discussed in the presented work. Above-mentioned location is found in the neighbourhood with a chemical factory Chemosvit Svit. The achieved results show that the soil hygiene in this region is mainly affected by the activity of this chemical factory. This factory is producing many risky substances and their results can be seen in the condition of soil hygiene and in the quality of farmed plants. The results of monitored heavy metals (Cd, Co, Ni) prove that the content of cadmium and nickel is the main polluting factor of soil in this region. The increased contents of these elements in soil produce a high risk of the uptake to plants. This further affects the technological quality along with the quality of hygiene of farmed products and finally the food itself as well. A higher attention needs to be paid to cobalt too, because it proved quite high cumulation ability in soil.

Increasing of competitiveness of dairy products in Slovakia through the application of information systems

A. Látečková, M. Kučera, K. Brédová

Agric. Econ. - Czech, 2009, 55(8):384-391 | DOI: 10.17221/43/2009-AGRICECON

Global trends in world economy intervene into each sector of national economy. In the article, we focused on the dairy industry. The research was oriented at the national market of dairy products with the goal to assess the current situation on the market with these commodities. According to the acquired data, we compiled an overview of the current situation in the market and we pointed out the direction that should be followed by producers. The implementation of information systems is a necessary requirement to increase competitiveness in accordance with the specifics of dairy production.

Effects of putrescine and low temperature on the apoplastic antioxidant enzymes in the leaves of two wheat cultivars

T. Çakmak, Ö. Atici

Plant Soil Environ., 2009, 55(8):320-326 | DOI: 10.17221/1037-PSE

The effects of putrescine (a polyamine), low temperature and their combinations on the activities of apoplastic antioxidant enzymes were studied in the leaves of two wheat cultivars, winter (Dogu-88) and spring (Gerek-79). Fifteen-day-old wheat seedlings were treated with putrescine solutions (0.1, 1 and 10mM) prior to cold treatment (5/3°C). The activities of apoplastic catalase, peroxidase and superoxide dismutase were determined in the leaves both under normal and cold conditions at 1, 3 and 5 days. The results indicate that cold treatment significantly increased the activities of apoplastic catalase, peroxidase and superoxide dismutase in winter wheat while not generally affecting spring wheat. Under control conditions, the putrescine treatments were more effective in increasing the enzyme activities in winter wheat than in spring wheat. However, under cold conditions, the putrescine treatments surprisingly induced enzyme activities in spring wheat while generally reducing those in winter wheat leaves. The results show that putrescine may act as an agent inducing primary changes in the apoplastic antioxidant system of wheat leaves during reactive oxygen species-mediated damage caused by low temperature stress.

Leaf growth under temperature and light control

J. Repková, M. Brestič, K. Olšovská

Plant Soil Environ., 2009, 55(12):551-557 | DOI: 10.17221/93/2009-PSE

Dynamics of crop growth and photosynthesis are two main processes that are of major importance for adaptation of plants to their environment. Two experiments were carried out during 2005 and 2006 with sun and shaded barley plants. The results showed that leaf area increased with leaf position on the main stem up to leaf position 5 for sun and leaf position 6 for shaded plants, and then declined towards flag leaves. Air temperature affected leaf appearance, mainly at the beginning of the growing season. A positive correlation between leaf expansion duration (LED) and accumulated temperature sum was measured for both variants, LED linearly increased with temperature sum. Leaf expansion rate (LER) showed a similar dependence on accumulated air temperatures in both light variants. A strong relation was found between soil temperature and LER for the first four leaves of the main stem of shaded plants in 2006. In shaded environment the higher LER was associated with lower accumulated irradiance sum when light restriction supported an increase of leaf elongation and final leaf length.

Perception of the forest by the villagers of the Salonga National Park in the Democratic Republic of Congo

J. M. Ibesoa

J. For. Sci., 2009, 55(7):339-344 | DOI: 10.17221/92/2008-JFS

Effective forest management demands detailed knowledge of resources. Local forest users are usually the best source of information. In the Democratic Republic of Congo forest management partnerships between local people and government staff have become more common. A proper understanding of local perceptions of the forest is needed. This study was designed and guided by a multidisciplinary team including a sociologist, a linguist and a forester. It identified and compared classification and management units. It also touched on the different uses of the forest products, the species that provided these products and the locations of these species.

Effect of Lactococcus sp. on the growth of Listeria sp. in the model UHT milk system

Eva ŠVIRÁKOVÁ, Ivana SLOŽILOVÁ, Petr TICHOVSKÝ, Milada Plocková

Czech J. Food Sci., 2009, 27(11):SII8-SII11 | DOI: 10.17221/672-CJFS

The work was aimed at the growth suppression of cultured listerias strains by cultured lactococci strains or commercial mesophilic cheese cultures during common cultivations in the model UHT milk system (0.5% w/w of milk fat content) at 30°C during 18 h aerobically. Milk was primarily fermented by lactococci at the level of 108 CFU/ml and secondarily contaminated by listerias at the level of 103 CFU/ml. The most intensive growth suppressions of both Listeria innocua (CCM 5884 or Ln-03) strains were caused by Lactococcus lactis subsp. lactis (LCC 416 or CHCC 2281) strains or DELVO-ADD® 100-X DSF cheese culture; the listerias growth reductions was from the level of 103 CFU/ml to 100 CFU/ml. Obtained results should be applied to dairy industry provided that HACCP, GHP and GMP systems must be observed.

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