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The aim of this work was to observe the influence of different hydrocolloids on changes in the rheological properties of processed cheese and their analogues within the process of cooling depending on the type of the fat used (butter, coconut fat and palm oil). κ-carrageenan, ι-carrageenan, λ-carrageenan, arabic gum and locust bean gum were used at a concentration of 1.0% w/w. With the decreasing temperature during the cooling period, an increase in the complex modulus (G*) was observed in all samples tested. Within the cooling period, the sample with the addition of κ-carrageenan showed both the most significant increase in G* in comparison with the control and the highest values of hardness after a 7-day storage period regardless of the type of the fat used. The samples with coconut fat were assessed as the hardest. On the other hand, the samples with palm oil showed the lowest hardness (with the same hydrocolloid used). In the gelling hydrocolloids (κ- and ι-carrageenan), only small changes in temperature of coil-to-helix transition were observed (in range of 2-7 °C) as a result of the addition of different types of fat. © 2013 Society of Dairy Technology.

The objective of our study was to compare the effect of addition of decarboxylase positive strain of Lactococcus lactis subsp. lactis on biogenic amine production, intensity of proteolysis and changes of hardness during ripening of white brined cheese. Model samples were kept under 10 degrees C for 56 days. The FAA content of cheese and hardness of samples were increasing during ripening. Significant differences in FAA content and also hardness were not found between control samples and samples with decarboxylase positive lactococci (P >= 0.05). Production of biogenic amine was more intense in sample with addition of decarboxylase positive lactococci (especially during first 28 days of ripening) and depends on initial micro flora during first stage of ripening. However, environmental conditions and ripening time are important factors which play major role in biogenic amine production through the microorganism growth in following ripening phases.

The aim of this work was to observe the effects of emulsifying salts composed of trisodium citrate and sodium phosphates with different chain length (disodium phosphate (DSP), tetrasodium diphosphate (TSPP), pentasodium triphosphate (PSTP) and sodium salts of polyphosphates with 5 different mean length (n ≈ 5, 9, 13, 20, 28)) on hardness of processed cheese spreads. Hardness of processed cheese spreads with selected binary mixtures of the above mentioned salts were also studied. Measurements were performed after 2, 9 and 30 days of storage at 6 °C. Hardness of processed cheese increased with increase in chain length of individually used phosphates. Majority of applied binary mixtures of emulsifying salts had not significant influence on hardness charges in processed cheese spreads. On the other hand, a combination of phosphates salts (DSP with TSPP) was found, which had specific effect on hardness of processed cheese spreads. Textural properties of samples with trisodium citrate were similar compared to samples with DSP. © 2013 Potravinarstvo.

The contribution is focused on risk analysis in food microbiology. This paper evaluates the effect of selected factors on tyramine production in bacterial strains of Lactococcus genus which were assigned as tyramine producers. Tyramine is a biogenic amine sythesized from an amino acid called tyrosine. It can be found in certain foodstuffs (often in cheese), and can cause a pseudo-response in sensitive individuals. The above-mentioned bacteria are commonly used in the biotechnological process of cheese production as starter cultures. The levels of factors were chosen with respect to the conditions which can occur in this technological process. To describe and compare tyramine production in chosen microorganisms, generalized regression models were applied. Tyramine production was modelled by Gompertz curves according to the selected factors (the lactose concentration of 0-1% w/v, NaCl 0-2% w/v and aero/anaerobiosis) for 3 different types of bacterial cultivation. Moreover, estimates of model parameters were calculated and tested; multiple comparisons were discussed as well. The aim of this paper is to find a combination of factors leading to a similar tyramine production level. © 2013 AIP Publishing LLC.

Aim: To determine and evaluate amino acid profiles in algal biomass of green freshwater microalgae Chlorella kessleri, Scenedesmus quadricauda and Chlorella sp. and blue-green micro-alga (cyanobacterium) Spirulina platensis cultivated by various methods. To perform the comparison of amino acid contents in algal biomass originated from cultivation methods. Material and Methods: Selected species of green freshwater micro-algae and blue-green microalgea were cultivated under the autotrophic cultivation in laboratory, in an outdoor open circulating cascade-type cultivation apparatus in a thin-layer, in a solar photobioreactor and under the heterotrophic cultivation regime in a fermenter. Contents of seventeen amino acids in algal samples were determined by using ion-exchange chromatography. Results: Autotrophic growth regime in a solar photobioreactor and in an outdoor open circulating cascade-type cultivation apparatus in a thin-layer provided algal biomass with higher amino acid contents than cultivation in a laboratory regime and heterotrophic cultivation in a fermenter. Conclusion: Microalgae are considered as an unconventional source of amino acids, so it is important to monitor their amino acid composition. This work provides amino acid profiles of investigated green freshwater microalgae and blue-green microalgea in dependence on their cultivation methods. The content of amino acids in algal biomass is directly associated with the selected cultivation method and growth conditions (e.g. chemical composition of culture medium, quality of light, pH, turbulence, salinity and temperature) of algal cells. Further studies are needed to elucidate the influence of individual growth conditions that may lead to changes in amino acid composition in algal biomass.

The first aim of this work was to compare the influence of using two probes (a 100-mm plate and a 5-mm spherical probe) during a compression test on the trends of hardness changes during ripening of Edam cheese. Both of the above-mentioned probes were also applied in relaxation tests for a relaxation time of 30-300s (10 arbitrary times were used). By means of Peleg's model, the values of a parameter (the extent of material relaxation) and b parameter (the initial rate at which the stress relaxes) were calculated. Moreover, the values of a and b parameters, obtained during 10 different relaxation times of the probe after reaching the maximum deformation of the sample (30-300s), were compared (calculated on the basis of Peleg's model). Edam cheese during ripening (1-84 days) was used as a model product. The values of cheese hardness within the ripening period (determined by means of both of the above-mentioned probes) strongly correlated among themselves and also with the sensorially evaluated rigidity. Only a parameter was able to provide an adequate description of the actual changes in cheese within the ripening period but only at a relaxation time of ≤120s (after reaching the maximum deformation of the sample; valid for both probes tested). Longer relaxation times do not provide a relevant description of the changes in cheese texture during ripening. B parameter provided no relevant description of the changes in cheese during ripening in any of the relaxation times studied (concerning both probes). © 2013 Wiley Periodicals, Inc.

The aim of the study was to explore texture changes of Dutch-type cheese at its different locations during 126-day ripening at the temperature common for maturation of this type of cheese (10°C). Each block of cheese was divided into 3 slices and texture properties were studied in 13 segments evenly distributed in each slice. Due to cheese brining, a significant increase of hardness and elastic component was reported especially in the edge segments. During the subsequent ripening, both hardness and elastic component of natural cheese decreased gradually in all segments and slices. Studied parameters of individual parts of cheese did not demonstrate uniform rate of changes during the ripening period. In the whole experiment (even after 126-day ripening), hardness and elastic component of the cheese in core showed lower values compared to those obtained in the edge of all slices. Copyright © 2013 Taylor & Francis Group, LLC.

Formation of biogenic amines may occur in food due to metabolic activities of contaminating Gram-negative bacteria. Putrescine is assumed to be the major biogenic amine associated with microbial food spoilage. Gram-negative bacteria can form putrescine by three metabolic pathways that can include eight different enzymes. The objective of this study was to design new sets of primers able to detect all important enzymes involved in the production of putrescine by Gram-negative bacteria. Seven new sets of consensual primers based on gene sequences of different bacteria were designed and used for detection of the speA, adiA, adi, speB, aguA, speC, and speF genes. A newly developed touchdown polymerase chain reaction (PCR) method using these primers was successfully applied on several putrescine-producers. Selected PCR products were sequenced and high similarity of their sequences (99-91%) with known sequences of the corresponding genes confirmed high specificity of the developed sets of primers. Furthermore, all the investigated bacteria produced both putrescine and agmatine, an intermediate of putrescine production, which was confirmed by chemical analysis. The developed new touchdown PCR method could easily be used to detect potential foodborne Gram-negative producers of putrescine. The newly developed sets of primers could also be useful in further research on putrescine metabolism in contaminating microbiota. © 2012 Elsevier Ltd.

The dependence of textural parameters of processed cheeses (40%, w/w, dry matter content, 50%, w/w, fat in dry matter content) on the composition of ternary mixtures of phosphate emulsifying salts (disodium hydrogen phosphate - DSP; tetrasodium diphosphate - TSPP; sodium salt of polyphosphate - POLY) was modelled. The effects were studied in samples from cheeses with different maturity (2, 4 and 8 weeks) over a 30-day storage period at 6 degrees C. With a constant POLY content (below 60%) in the ternary mixtures, a rapid increase in hardness and a decrease in cohesiveness and relative adhesiveness was observed in products with a ratio of DSP to TSPP ranging in the instance of 1:1-3:4. The effect of a specific ratio of DSP to TSPP on the texture parameters decreased with increasing content of POLY in the mixtures. Neither the degree of maturity of the cheese nor a 30-day storage period affected these general trends. (C) 2012 Elsevier Ltd. All rights reserved.

The aim of the work was to monitor the content of 8 biogenic amines (histamine, tyramine, phenylethylamine, tryptamine, putrescine, cadaverine, spermidine and spermine) in 112 samples of raw freshwater and see fish, and other animals living in the water which are offered in restaurants in the Czech Republic. In approx. 15% of the sampled bodies, increased levels of biogenic amines (practically more than 100 mg/kg) have been observed. In 6 samples of fish, the concentration of histamine was higher than the limit specified in Commission Regulation (EC) No 2073/2005 (more than 200 mg/kg). The results pointed out the necessity of keeping the storage conditions (cooling and/or freezing chain) during the distribution of products to consumers. © 2012 Elsevier Ltd.

Biogenic amines have several important physiological functions but also can cause wide range of health problems when are consuming in high amount in food. Among the most serious toxicological effects of biogenic amines are undoubtedly possible carcinogenic effects of some polyamines, particularly putrescine. Putrescine could be formed by many bacterial strains. Putrescine can be produced by different metabolic pathways involving a larger number of enzymes. Possible detection of all important pathways by detecting the corresponding gene by PCR has not been sufficiently studied yet. In this paper we present a possible solution to this problem.

The aim of this study was to describe the development of selected biogenic amines (histamine; tyramine; phenylethylamine; putrescine; agmatine; and cadaverine) during the winemaking in 10 selected species grown in Central Europe in 2008. The analysis was performed using ion-exchange chromatography by the sodium-citrate buffers with the post-column ninhydrin derivatization and photometric detection. A comparison of the content of biogenic amines in red and wine varieties showed that red wines have higher concentrations of biogenic amines.

The aim of this study was to monitor of biogenic amines contents in commercial fermented products, especially various type of ripening cheeses and fermented meat products (15 cheese samples and nine dry fermented meat products obtained from Czech Republic, Slovak Republic, Poland, and Germany). Furthermore, the changes in samples during storage were also observed. The samples were stored at 6 +/- 1 degrees C. The samples were taken the first day of storage and the last day of shelf-life. The biogenic amines content was determined using ion-exchange liquid chromatography with post-column derivatization and photometric detection. The content of biogenic amines increased during storage. The highest biogenic amines content at the end of storage was observed in Dutch-type cheeses and in Smear cheeses, in both the concentrations exceeded 1 000 mg. kg(-1). Latter mentioned amount may have serious negative impact on consumer health. The lowest concentration of biogenic amines was detected in Blue cheese.

The simple and rapid solid-phase micro-extraction method using gas chromatography was used for the identification and quantification of volatile aroma compounds in various types of processed cheese analogues produced from different types of fat (butter, butter oil, coconut oil, palm oil, and sunflower oil). In total, 31 organic compounds belonging to five chemical groups were identified, with the alcohols and fatty acids quantitatively predominant. The contents of the aroma compounds (the so-called aroma profiles) of the analogues and corresponding fats used as raw materials were compared. Significant differences (p < 0.05) were found between samples. The highest total content of aroma compounds was found in coconut oil analogue ((547.30 +/- 9.82) mg kg(-1)), the lowest in palm oil analogue ((372.01 +/- 16.16) mg kg(-1)). The concentrations of aroma compounds in fats were substantially lower (p < 0.05) than in analogues. Hence, the largest number of aroma analogues came from Edam cheese used for production as a protein source.

The aim of the study was to explore production of seven biogenic amines (phenylethylamine, histamine, cadaverine, tyramine, putrescine, spermine and/or spermidine) by selected staphylococci and enterococci. Thirty three enterococcal strains isolated from rabbit meat (Oryctolagus cuniculus f. domesticus) and 21 staphylococcal strains isolated from intestinal content of trout (Salmo trutta morpha fario) were tested. Production of biogenic amines was evaluated after cultivation of the tested microorganisms in the de Man, Rogosa and Sharpe Broth (enterococci) or in the Brain Heart Infusion Broth (staphylococci). Both the above cultivation media were enriched with selected amino acids (histidine, tyrosine, arginine, ornithine and lysine; 2. g/L each) serving as precursors of biogenic amines. After cultivation, levels of the monitored biogenic amines in broths were analysed by a high performance liquid chromatography equipped with a UV/VIS DAD detector. Among 21 staphylococci, 18 strains produced tyramine or cadaverine, 13 strains formed putrescine or phenylethylamine and only one strain generated histamine. Two staphylococcal strains produced cadaverine levels above 1000. mg/L. Among 33 enterococcal strains, 27 formed cadaverine, 18 strains produced tyramine, 10 strains generated phenylethylamine, and 2 strains gave putrescine. Most of the tyramine producing enterococci generated more than 1000. mg/L of this biogenic amine. Production of spermine or spermidine by the studied strains was not proved.

The aim of this study was to monitor levels of minerals in mare's colostrum in the fi rst 3 days after foaling. Colostrum samples from four warm-blood mares (in three repetitions) were analysed 2, 12, 24, 36, 48 and 72 hours postpartum. The samples were obtained by hand milking. Calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K), zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn) contents were analysed in each sample. Non-signifi cant decrease of postpartum Ca and Na contents was found in the analysed samples. Signifi cant diff erences (P < 0.05) in P content were detected between 2 and 36 hours postpartum. Content of Mg showed statistically signifi cant diff erences (P < 0.05) during the period after foaling (2, 24, 36, 48 and 72 hours post foaling). Mg concentration reached its maximum (21.8 g.kg-1 of dry matter) 2 hours postpartum and it dropped to its lowest level (5.27 g.kg-1 of dry matter) 48 hours after foaling. Similarly, the highest K content (signifi cant in relation to values obtained 36, 48 and 72 hours postpartum) was detected 2 hours after foaling while the lowest K level (37.96 g.kg-1 of dry matter) was found 48 hours postpartum. As regards the microelements, Cu showed insignifi cant diff erences in its postpartum levels (P > 0.05). Besides growth of Fe levels, decrease of Zn and Mn (P > 0.05) was also observed.

The aim of this study was to explore the effect of elevated temperature (16 degrees C) on ripening of Dutch-type cheese. Three slices of each cheese block were further divided into three layers. The processes in the control samples of cheese ripening at 10 degrees C were also monitored. The contents of free amino acids in accelerated cheese were two times higher than were those in control samples. The highest contents of free amino acids were observed in the cores of all slices of cheeses ripening at both temperatures. The contents of tyramine, in layers of the studied slices, reached almost 500 mg kg(-1) during 56 days of the experiment. The contents of biogenic amines in the edges grew even higher. Accelerated cheese showed faster equalisation of hardness than did control samples. The increase of temperature by 6 degrees C can reduce the ripening time in cellars by approximately one half. (C) 2011 Elsevier Ltd. All rights reserved.

Combined effects of concentration of lactose (5 g/L), NaCl (20 g/L) and aero/anaerobiosis on production of tyramine by Enterococcus durans CCDM 53 were subjected to a study. The influence of the above factors and temperature of cultivation (10 ± 1 °C) was monitored under conditions applied in real technological processes of cheese production; the enterococci act as non-starter lactic acid bacteria. Production of tyramine by E. durans CCDM 53 was mainly influenced by both concentration of NaCl in cultivation medium and presence/absence of oxygen in the environment. The highest production of tyramine occurred during cultivation under anaerobic conditions in the presence of the highest (20 g/L) applied concentration of NaCl and lactose (5 g/L). In the media with equal concentrations of NaCl and lactose, the concentrations of tyramine grew higher under anaerobic conditions than in aerobic environment. Regarding cultivation media with various levels of NaCl and lactose, higher production of tyramine was always found in the anaerobic environment. © 2012 Springer-Verlag.

Altogether 114 samples of alcoholic and non-alcoholic bottled beer produced in 28 breweries in the Czech Republic were monitored for levels of biogenic amines (BA) and polyamines (PA). The beers were analysed immediately after purchase and then at the end of the best-before period (storage temperature 8 +/- 1 degrees C). The concentrations of histamine, phenylethylamine and tryptamine in the studied samples were very low (mostly under 30 mg L-1). The studied PA spermine and spermidine also occurred in small amounts. Nevertheless, the levels of tyramine, putrescine and cadaverine reached significant values, especially in alcoholic beers. In almost 25% of the tested samples of alcoholic beers (at the end of the best-before period), the total amount of all the monitored BA and PA exceeded the 'healthy' level of 100 mg L-1, which is considered toxicologically significant, especially in alcoholic beverages. Copyright (C) 2012 The Institute of Brewing & Distilling

This paper aims to study the dependence of the hardness of processed cheese spreads on the composition of binary mixtures of phosphate emulsifying salts consisting of disodium hydrogenphosphate, tetrasodium diphosphate, pentasodium triphosphate, and/or sodium salt of polyphosphate and on the number of days of storage. The main goal was to find suitable statistical models in order to describe the dependence of the hardness examined on the composition of binary mixtures. Polynomial regression proved to be suitable for the global behaviour of the statistical relationship observed. Detailed observation of local changes was made by means of a fuzzy inference system. In binary mixtures of polyphosphate combined with monophosphate, diphosphate or triphosphate, hardness was gradually increasing with rising amount of polyphosphate in the mixture. In binary mixtures of monophosphate combined with diphosphate or triphosphate, a rapid increase in the hardness of the samples was determined when the proportion of diphosphate or triphosphate in the mixture was rising up to 50-60 %. A further increase in diphosphate or triphosphate content in the binary mixture (above 60 %) resulted in a similarly rapid decrease in the hardness of the processed cheeses.

The aim of this work was to study the dependence of hardness of processed cheese spreads on the composition of binary mixtures containing disodium hydrogenphosphate, tetrasodium diphosphate, pentasodium triphosphate, and/or sodium salt of polyphosphate using advanced statistical models. Eleven percentage ratios were applied in each of the 6 types of binary mixtures. The study was focused on finding of suitable models in order to describe the dependence of hardness on the composition of binary mixtures. These models use fuzzy sets - especially as Fuzzy Inference System. Fuzzy inference system is able to identify possible nonlinear dependence between input variables and output variables in process. It can also work with data described in vague terms. In mixtures of polyphosphate with the other phosphates studied, hardness was increasing with the rising amount of polyphosphates within the mixture. In binary mixtures of monophosphate with diphosphate or triphosphate, a rapid grow in sample rigidity was determined when the amount of diphosphate or triphosphate in the mixture was rising (up to 40-60%). A further increase in diphosphate or triphosphate concentration (above 50 - 60%) resulted in a drop in rigidity of processed cheeses. Hardness of samples was increased during 30-day storage.

The impact of four different regimes of heat sterilization (110C for 100 min, 115C for 32 min, 120C for 10 min and 125C for 3.2 min) on the properties of processed cheeses was evaluated. Also, nonsterilized samples were analyzed. Samples without and with the addition of lactose (0.5-2.0% w/w) were studied because lactose might be present in raw materials at various concentrations and might significantly affect processed cheese quality. All the sterilization regimes ensured inactivation of microflora. When the sterilization temperature was reduced (with simultaneously prolonged exposure time) the samples showed worse sensory properties. Significant hydrolytic changes of proteins and larger amino acid losses were also detected. The smallest changes were noted in products treated at 125C for 3.2 min. The heat treatment at 120C for 10 min caused acceptable modification of cheese properties. Addition of lactose higher than 1.0% w/w was found unsuitable for the production of sterilized processed cheeses. © 2010 Wiley Periodicals, Inc.

The dependence of hardness, adhesiveness and cohesiveness of processed cheese spreads on the composition of binary mixtures of disodium hydrogen phosphate, tetrasodium diphosphate, pentasodium triphosphate, and/or sodium salt of polyphosphate was studied. Suitable statistical models to describe the dependence of the texture parameters examined on the composition of binary mixtures were investigated. Each of the 6 types of binary mixtures was applied in 11 percentage ratios of each component. In binary mixtures of polyphosphate combined with monophosphate, diphosphate or triphosphate, hardness gradually rose with the increasing proportion of polyphosphates within the mixture. In binary mixtures of monophosphate combined with diphosphate or triphosphate, a rapid growth in hardness of the samples was observed when the proportion of diphosphate or triphosphate in the mixture increased (up to 50-60%). A further increase in diphosphate or triphosphate content (above 60%) resulted in a rapid decrease in hardness of the processed cheeses. © 2011 Elsevier Ltd.

The aim of this work was to study, under model conditions, combined effects of the concentration of lactose (0-1% w/v), NaCl (0-2% w/v) and aero/anaerobiosis on the growth and tyramine production in 3 strains of Lactococcus lactis subsp. lactis and 2 strains of L lactis subsp. cremoris. The levels of the factors tested were chosen with respect to the conditions which can occur during the real process of natural cheese production, including the culture temperature (10 +/- 1 degrees C). In all strains tested, tyrosine decarboxylation was most influenced by NaCl concentration; the highest production of tyramine was obtained within the culture with the highest (2% w/v) salt concentration applied. Two of the strains L. lactis subsp. lactis produced tyramine only in broth with the highest NaCl concentration tested. In the remaining 3 strains of L lactis, tyramine was detected under all conditions applied. The tested concentration of lactose and aero/anaerobiosis had a less significant effect on tyramine decarboxylation. However, it was also found that at the same concentrations of NaCl and lactose, a higher amount of tyramine was detected under anaerobic conditions. In all strains tested, tyramine decarboxylation started during the active growth phase of the cells. (C) 2011 Elsevier B.V. All rights reserved.

Selenium (Se) is an important element associated with the enhancement of antioxidant activity in organisms. Potato is very suitable for fertilisation with Se (biofortification). The experiment was performed to examine the effect of foliar application of Se as sodium selenite (200 or 400 g Se/ha) at the tuberisation stage on a spectrum of amino acids in tubers of varieties. The trends of amino acids were consistent in both years of the study. Application of Se increased the relative content of total essential (EAA) and non-essential (NEAA) amino acids relative to the controls (Karin: EAA 16.81-21.73% and NEAA 14.18-18.63%; Ditta: EAA 4.71-13.00% and NEAA 5.78-6.49%). The increase in the content of phenylalanine (Phe) was particularly significant (up to 48.9%) when also the contents of aspartic acid (Asp), glutamic acid (Glu), threonine (Thr), and tyrosine (Tyr) increased significantly compared with the controls. The results of changes in the content of isoleucine (Ile), leucine (Leu), lysine (Lys), methionine (Met), valine (Val), alanine (Ala), arginine (Arg), proline (Pro), cysteine (Cys), glycine (Gly), histidine (His), and serine (Ser) were also discussed. The highest dose of selenium is shown as a stress factor. Its toxic effects resulted in a change of amino acid contents.

Phosphates offer a range of possibilities when used in meat and poultry productions. Food grade phosphates are used in meat products for several reasons such as changing and/or stabilizing of pHvalue, increasing water holding capacity in order to lead to higher yields, decreasing losses of weight in cooking, improving texture and sensory properties (tenderness, juiciness, color and flavor), extending shelf-life, etc. In addition, phosphates in meat products are also sources of the supply of phosphorus for consumers through diet, which is an essential mineral for the lives of humans. This review is focused on phosphates' properties, functions, application in meat and poultry products as well as influence on health. © 2011 Academic Journals.

Cílem této práce bylo zhodnocení možného účinku náhrady kukuřice v krmné dávce na obsah aminokyselin v kravském mléce. Dojnice byly krmeny směsnou krmnou dávkou složenou z kukuřice, jetelové siláže a sena. Rozdílnost v krmné dávce byla v jadrném krmivu. První skupina (krmena kukuřicí) byla skupinou kontrolní, ostatní dvě skupiny byly experimentální, jedna byla krmena pšenicí a druhá obilninou tritikale. V průběhu šesti týdnů bylo odebráno celkem 26 vzorků mléka od dojnic plemene České strakaté. Krmné skupiny byly vyváženy v dojivosti, laktačních dnech a v pořadí laktace. Vzorky krmiv a stejně tak i mléka byly upraveny pro analýzu pomocí kyselé a oxidativně-kyselé hydrolýzy. Analýza aminokyselin v hydrolysátech byla provedena pomocí kapalinové chromatografie (AAA 400 analyzátor) za použití sodno-citrátových pufrů a ninhydrinové detekce. Celkové množství dusíku bylo stanoveno dle Kjehldahla a hrubý protein daných vzorků byl stanoven pomocí vynásobení hodnoty celkového dusíku vhodným faktorem 6,38. Vysoká hodnota hrubého proteinu v pšenici neovlivnila složení mléka získaného od experimentální skupiny krmené touto obilninou. Z pohledu obsahu aminokyselin ve vzorcích mléka nemůže být žádná z testovaných obilnin doporučena jako plnohodnotná náhrada kukuřice. Každé krmivo je bohatým zdrojem mnohých a typických aminokyselin v mléce. Avšak tritikale (kultivar Kitaro) se může zdát jako vhodnou náhradou kukuřice vzhledem k lepší využitelnosti hrubého proteinu, celkovému složení mléka a zdravotním ukazatelům mléčné kvality., The aim of this study was to evaluate the possible effects of maize replacement in feeding rations on the amino acid content in cows´ milk. Cows were fed total mix ration based on the maize, clover silage and hay. There was a difference in the concentrate of the feeding ration. The first group (fed maize) was the control group, another two groups were experimental, one fed wheat and second fed triticale. During six weeks, totally 26 milk samples were taken from dairy cows of Czech Pied breed. Feed groups were preferably balanced in terms of milk yield, stage and number of lactations. The samples of feedstuff s as well as milk were modified for the analysis using acidic and oxidative hydrolyses. The analysis of amino acids content and composition of the sample hydrolysates was performed chromatographically by an AAA 400 analyzer, using Na-citrate buffers and ninhydrin detection. Total nitrogen content was determined according to Kjehldahl and the crude protein of the samples was determined by conversion from the nitrogen content multiplied by appropriate factor. The high content of crude protein in wheat did not influenced composition of milk from dairy cows fed this type of feedstuff. With respect to resulting amino acid content and composition of milk samples, none of the tested grains can be recommended as a full-value maize replacement. Each feedstuff is an abundant source of several and typical amino acids in milk. However, triticale (cultivar Kitaro) seems to be acceptable replacement of maize owing to better crude protein efficiency, composition and health indicators of milk quality.

Proces výroby tavených sýrů je z hlediska používaných tavicích teplot (a pH výrobku) možno považovat za ?pasteraci sýra?. Mezi faktory ovlivňující trvanlivost a jakost tavených sýrů patří zejména mikrobiologická kvalita použité vstupní suroviny, důsledné dodržování hygienických podmínek během výrobního procesu, dále pak druh obalových materiálů a způsob (podmínky) skladování. Jakost tavených sýrů je závislá nejen na použitých ingrediencích, ale i na dalších parametrech, jako je hodnota vodní aktivity taveného sýra, jeho pH, přítomnost solí a emulgačních látek nebo množství tuku ve výrobku., Regarding the melting temperatures used (and pH of the product), the course of processed cheese production can be considered ?pasteurization of cheese?. Factors affecting the shelf-life and quality of processed cheeses include the microbiological quality of the raw material used, strict compliance with hygienic conditions during production and the quality of wrapping materials and storage conditions. The quality of processed cheeses is also influenced by other parameters, such as the value of water activity of the product, its pH, the presence of salts and emulsifying agents, or the content of fat.

Základní surovinou pro výrobu tavených sýrů jsou přírodní sýry, které jsou tepelně upravovány za přídavku tavicích solí. Při procesu tavení za zvýšených teplot dochází k inaktivaci převážné části vegetativních forem mikroorganizmů, včetně bakterií čeledi Enterobacteriaceae. Tavící teploty však nejsou dostatečné pro usmrcení endospor, které proces přežívají, často však bývají oslabeny. Z mikrobiologického hlediska je nejzávažnějším problémem kontaminace tavených sýrů grampozitivními sporulujícími tyčinkami rodů Bacillus a Clostridium. Zvláště nežádoucí jsou pak sporulující mikroorganizmy druhů Clostridium butyricum, C. tyrobutyricum, které jsou původci duření sýrů, C. sporogenes a C. lentoputrescens způsobující bílou hnilobu sýrů. Přítomnost Bacillus subtilis, B. brevis a B. cereus var. mycoides je nežádoucí zejména kvůli vzniku hořké chuti. Mikrobiální jakost tavených sýrů je závislá jak na mikrobiologické kvalitě použité suroviny, tak na sekundárních vlivech, které jsou většinou spojeny s dalšími možnostmi kontaminace během výroby, balení a distribuci těchto produktů., The main ingredients for processed cheese production are natural cheeses, which are treated by heat with the addition of emulsifying salts. During the melting process the majority of vegetative forms of microorganisms are inactivated, including bacteria of the family Enterobacteriaceae. However, the melting temperatures are not sufficient for killing bacterial endospores, although the spore-forming microorganisms are often weakened. From a microbiological point of view, the most significant contamination problem of processed cheeses is caused by Gram-positive spore-forming rod-shaped bacteria of the genus Bacillus and Clostridium. Highly undesirable microorganisms are spore-forming species Clostridium butyricum, C. tytobutyricum, which cause blowing of cheeses and C. sporogenes and C. lentoputrescens, which are responsible for a white putrefaction of cheeses. Bacillus subtilis, B. brevis a B. cereus var. mycoides are dangerous mainly due to the creation of a bitter taste. Microbial quality of processed cheeses depends on the quality of ingredients, as well as on secondary factors which are in most cases related to other possibilities of contamination during production, wrapping and distribution of these products.

Cílem práce je vyhodnotit vliv 4 různých sterilačních režimů (100°C 100 min, 115°C 32 min, 120°C 10 min and 125°C 3.2 min ? s konstantním smrtícím účinkem na mikroorganizmy) na vybrané chemické (pH, obsah celkového a využitelného lyzinu, obsah amoniaku), mikrobiologické a senzorické (barva a přijatelnost) vlastnosti tavených sýrů, v závislosti na obsahu laktózy (0 ? 2 % hm.). Všechny sterilační režimy byly dostatečné pro inaktivaci sledovaných mikroorganizmů. Klesající teplota sterilace a adekvátně rostoucí délka sterilace způsobila tmavnutí tavených sýrů a pokles jejich přijatelnosti. Zároveň docházelo ke ztrátám lyzinu a nárůstu obsahu amoniaku. Ve srovnání s nesterilovanými tavenými sýry byly nejmenší změny pozorovány u sýrů podrobených sterilačnímu režimu 125 °C (3,2 min) a 120 °C (10 min). Zhoršení kvality tavených sýrů bylo výraznější s rostoucím obsahem laktózy., The aim of present work is to evaluate the impact of four different sterilizing modes (100°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 their lactose addition (0.0 ? 2.0 % w/w). All sterilizing 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 sterilization temperature kept for adequately prolonged period of time caused darkening of the processed cheese and decline their acceptability. Consequently, greater losses of lysine and ammonia content rise occurred when sterilization temperature decreased. Compared to non-sterilized products, the smallest changes were detected in cheese treated with temperatures 125°C for 3.2 min and 120°C for 10 min. The decrease of processed cheese quality was more apparent with the growing lactose concentration.

Cílem práce bylo popsat vývoj obsahu vybraných biogenních aminů (histaminu, tyraminu, putrescinu a kadaverinu) ve 4 vrstvách eidamského sýru v závislosti na 3 režimech zrání/skladování v průběhu 98 dnů. Pro analýzu biogenních aminů byla použita iontově-výměnná chromatografie. Dalším cílem bylo identifikovat mikrobiální původce biogenních aminů v analyzovaném materiálu. Pro identifikaci izolovaných bakterií byly použity fenotypové znaky a PCR fingerprinting. Nejvyšší obsahy tyraminu, putrescinu a kadaverinu byly zjišťovány u sýrů uchovávaných po celou dobu sledování ve zracím sklepě při 10°C. Nižší obsahy biogenních aminů byly zjišťovány u vzorků, které byly po 38 dnech ve zracím sklepě (10°C) přesunuty do chladírenského zařízení (5°C). Nejnižší koncentrace biogenních aminů byly detekovány u sýrů, které byly po 23 dnech ve zracím sklepě (10°C) přesunuty do chladírenského zařízení (5°C). Histamin nebyl v průběhu 98 dnů ani u jednoho režimu detekován. Jako hlavní původci testovaných biogenních aminů v analyzovaných sýrech byli detekováni non-starterové bakterie mléčného kvašení Lactobacillus curvatus subsp. curvatus, komplex Lactobacillus casei/paracasei a Lactobacillus plantarum. U starterových bakterií Lactococcus lactis subsp. lactis a Lactococcus lactis subsp. cremoris nebyla dekarboxylázová aktivita detekována., The aim of the work was to describe the development of selected biogenic amines (histamine, tyramine, putrescine and cadaverine) in 4 layers of Dutch-type cheese (Edam cheese) depending on 3 ripening/storage regimes during a 98-day period. Biogenic amines were analysed by means of ion-exchange chromatography. A further goal was to identify microbial sources of biogenic amines in the material analysed. Phenotype characterization and repetitive sequence-based PCR fingerprinting were used to identify the isolated bacteria. The highest content of tyramine, putrescine and cadaverine was determined in cheeses stored in a ripening cellar at a temperature of 10°C during the whole observation period. Lower biogenic amines content was determined in samples which were moved into a cold storage device (5°C) after 38 days of storage in a ripening cellar (10°C). The lowest concentrations of biogenic amines were detected in cheeses which were moved into a cold storage device (5°C) after 23 days of storage in a ripening cellar (10°C). During the 98-day period, histamine was not detected in any of the regimes. Within the cheeses analysed, non-starter lactic acid bacteria Lactobacillus curvatus, Lactobacillus casei/paracasei and Lactobacillus plantarum were detected as the main producers of the biogenic amines tested. In starter bacteria Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris the decarboxylase activity tested was not detected.

Byla zkoumána antifungální aktivita monoacylglycerolů s C8, C10 a C12 uhlíky v řetězci (1-monokaprin, 1-monokaprylin a 1-monolaurin) v podmínkách in vitro a na mikromycety izolované z kontaminovaného pečiva. Všechny testované monoacylglyceroly vykazovaly antimykotické účinky v koncentracích rovných nebo vyšších než 32,5 mg/l. Monolaurin měl lepší inhibiční účinek vůči Monascus ruber, růst druhů rodu Penicillium byl lépe potlačen monokaprinem a monokaprylinem. Použití vodného roztoku monoacylglycerolů na povrch čerstvě upečeného pečiva zabránil zhoršování jeho jakosti po dobu nejméně 14 dnů. Ošetření povrchu chleba pomocí monoacylglycerolů se zdá být vhodným postupem pro pekárenské výrobky s prodlouženou dobu skladování., The antifungal activity of monoacylglycerols with 8, 10 and 12 carbon chains (1-monocaprylin, 1-monocaprin and 1-monolaurin) against filamentous fungi isolated from contaminated bread (Penicillium piceum, Penicillium chrysogenum, Penicillium sp. and Monascus ruber) as well as against the selected microorganisms (Aspergillus niger, Penicillium roqueforti, Penicillium jensenii, Alternaria sp. and Phoma sp.) was investigated. All the tested monoacylglycerols showed antifungal efficacy at the concentrations equal or higher than 32.5 mg/L. Monolaurin shows better inhibition effect against Monascus ruber, the growth of Penicillium species was better inhibited with monocaprin and monocaprylin. Application of aqueous monoacylglycerols solution on the surface of freshly baked bread prevents its deterioration for at least 14 days, even during the storage in the environment being strongly contaminated with tested microorganisms. Protection of bread loaf surface using monoacylglycerols solutions seems to be suitable procedure for treatment of bakery products with prolonged storage period.

Cílem této studie bylo pomocí iontově-výměnné chromatografie zjistit produkci biogenních aminů (histaminu, tyraminu, putrescinu, kadaverinu, agmatinu, sperminu a spermidinu) u 88 gramnegativních bakterií izolovaných z povrchu drůbeže (41 izolátů bakterií čeledi Enterobacteriaceae, 21 izolátů rodu Aeromonas, 16 izolátů rodu Pseudomonas a 10 izolátů ostatních gramnegativních tyčinek). Největší produkce byla zaznamenána u enterobakterií, kde byla v kultivačním médiu po inkubaci bakterií zjištěna přítomnost tyraminu, agmatinu, putrescinu i kadaverinu. V nejvyšší koncentraci byly produkovány putrescin a kadaverin. U 19 kmenů enterobakterií byla zjištěna přítomnost 2 a více biogenních aminů (nejčastěji putrescin a kadaverin zároveň, popř. i agmatin). U izolátů zařazených do rodu Aeromonas byla zjištěna produkce putrescinu u 11 kmenů, z nichž 5 zároveň produkovalo i kadaverin. Přítomnost dalších biogenních aminů nebyla u těchto izolátů zjištěna. U žádného z izolátů rodu Pseudomonas nebyla zjištěna produkce biogenních aminů., The aim of this study is to explore production of biogenic amines (histamine, tyramine, putrescine, cadaverine, agmatine, spermine and spermidine) by 88 gram-negative bacteria isolated from poultry skin (41 isolates of family Enterobacteriaceae, 21 isolates of genus Aeromonas, 16 isolates of genus Pseudomonas, and 10 isolates of other gram-negative rods). Ion-exchange chromatography was employed to analyze the above mentioned amines. Enterobacteria were found the largest producers of amines with proved presence of tyramine, agmatine, putrescine, and cadaverine in cultivation broth after incubation of bacteria. Putrescine and cadaverine were the most abundant products. Presence of at least 2 biogenic amines, i.e. mainly concurrent presence of putrescine and cadaverine, was revealed in 19 enterobacteria strains. Eleven isolates classified into Aeromonas genus produced putrescine and five of them formed also cadaverine. The other observed biogenic amines (histamine, spermine and spermidine) were not found among tested isolates. Production of biogenic amines by any Pseudomonas family isolates was not proved.

Možnosti snížení kontaminace potravin si udržují velkou pozornost zejména ve snaze prodloužit trvanlivost potravin. Hlavní faktor ovlivňující trvanlivost je rychlost růstu mikroorganizmů způsobujících kažení. Cílem této studie bylo zjistit vliv organických látek (kyseliny citrónové [CA], kyseliny mléčné [LA] a sorbanu draselného [PS]) na mikroflóru kůže chlazených kuřat. Aplikace těchto látek inhibovala mikrobiální růst a prodloužila životnost jednotlivých kusů. Redukce mikroorganizmů byla významná po aplikaci 10% CA a 2% LA, avšak nejúčinnější byla kombinace 2% LA s 0,2% PS. Senzorickou analýzou bylo vyhodnoceno, že 10% CA je nepřijatelná pro následnou konzumaci upraveného masa. Nicméně, kuřata ošetřená danou směsí prokazovala lepší organoleptické vlastnosti než kontrola. Použití kombinace potravinářských konzervantů může přispět k významným úbytkům patogenů a mikroflóry způsobující kažení drůbeže, High attention is paid to the decontamination systems in an effort to prolong the shelf life of food products. The major factor determining shelf life is the rate of spoilage microorganism growth. This study was designed to evaluate the influence of organic substances (citric acid [CA], lactic acid [LA] and potassium sorbate [PS]) on chilled chicken skin microflora. Application of organic substances inhibited microbial growth and prolonged the shelf life of carcasses. Microbial reduction after application of organic acids was significant in case of 10% w/v CA and 2% v/v LA, and the most effective was combination of 2% v/v LA with 0.2% w/v PS. Sensory analysis found that application of 10% CA was not acceptable. However, chickens treated with the mixture showed better organoleptic properties than control. The use of food preservatives in combination may contribute to significant reductions of spoilage and pathogen microbes on poultry

Práce se zabývala možnostmi náhrady tradičních tavicích solí na bázi fosforečnanů a citranů různými hydrokoloidy při výrobě tavených sýrů. Cílem bylo vyrobit tavený sýr bez aplikace tradičních tavicích solí, který by byl homogenní. Pro studium byly vybrány modifikovaný škrob (s vázaným oktenyljantaranem sodným), low methoxyl pectin (sám i v kombinaci s emulgátorem ? lecitinem), locust bean gum, ? carrageenan a ? carrageenan. Hydrokoloidy byly aplikovány v koncentracích ? 1 % (w/w) finálního výrobku. Homogenita výrobků byla posuzována senzorickou analýzou, obrazovou analýzou mikroskopických preparátů a dynamickou oscilační reometrií. Modelové tavené sýry (bez tradičních tavicích solí) s 40 % (w/w) sušiny a 55 % (w/w) tuku v sušině, do kterých byly aplikovány 1.00 % (w/w) ? carrageenan nebo ? carrageenan, byly všemi třemi použitými metodami zhodnoceny jako homogenní., Different hydrocolloids were examined as possible replacements for traditional phosphate- and citrate-based emulsifying salts in processed cheese production. The following hydrocolloids (at concentrations in the final product of ? 1.0% w/w) were chosen: modified starch (with bound sodium octenyl succinate), low methoxyl pectin (alone or combined with lecithin), locust bean gum, ? carrageenan and ? carrageenan. The products were assessed by sensory analysis, microscopic image analysis and dynamic oscillatory rheometry. Modified starch, locust bean gum and low methoxyl pectin could not be recommended as replacements for traditional emulsifying salts. Model processed cheeses without traditional emulsifying salts of 40% (w/w) dry matter and 55% (w/w) fat-in-dry matter containing 1.0% (w/w) ? carrageenan or ? carrageenan were found to be homogeneous, however the products were hard with fracturable texture.

Ve dvouletých polních experimentech byl aplikován dusík ve formě močoviny (0, 120 and 240 kg N/ha) k zrnové kukuřici(Zea mays L.) hybridu KWS 2376. Dvouletý průměrný obsah celkového dusíku v zrně při sklizni byl 1,54 %. Největší dávka N redukovala většinu ze 17 stanovenýc aminokyselin (AA)v zrně ve srovnání s ostatními variantami. Pravděpodobnou příčinou tohoto jevu mohl být negativní vliv na cyklus trikarboxylových kyselin nebo deficience uhlíkatých skeletů pro asimilaci NH4+ do amidů a aminokyselin. Obsah limitující aminokyseliny lysinu nebyl ovlivněn N-hnojením, přičemž dvouletý průměrný obsah byl 2.02 mg/g sušiny. Z hlediska rozdílů ve hnojení byl zřetelný vliv ročníku s maximální akumulací aminokyselin serinu, prolinu, methioninu, threoninu, argininu a lysinu. Zvyšující se dávky dusíku redukovaly akumulaci asparaginu a glycinu a naopak zvyšovaly akumulaci tyrosinu. Dávky dusíku mají signifikantní efekt na maximální akumulaci valinu, isoleucinu, leucinu, phenylalaninu, histidinu, cysteinu a alaninu již při první zvýšené dávce dusíku(120 kg N/ha)., In two-year field experiments, nitrogen (N) in the form of urea (0, 120 and 240 kg N/ha) was applied to grain maize (Zea mays L.) hybrid KWS 2376. The two-year mean content of total grain N at harvest was 1.54%. The highest N dose reduced most of the 17 amino acids (AA) analysed in the grain compared with the other treatments. Possible reasons for this could be an adverse effect on the tricarboxylic acid cycle or deficiency of carbon skeletons for the assimilation of NH4+ into amides and amino acids. The content of the limiting amino acid lysine was not influenced by N fertilisation, with a mean two-year content of 2.02 mg/g DM. Taking into account the differences in fertilisation the effect of the year was seen in the maximal accumulation of amino acids serine, proline, methionine, threonine, arginine and lysine. Increasing rates of nitrogen reduced the accumulation of asparagine and glycine, and, on the contrary, increased the accumulation of tyrosine. Nitrogen rates have a significant effect on the maximal accumulation of valine, isoleucine, leucine, phenylalanine, histidine, cysteine and alanine and appeared as early as after the first increased rate of nitrogen (120 kg N/ha).

The aim of this research was to study the formation of seven biogenic amines (histamine, agmatine, spermine, spermidine, cadaverine, putrescine and tyramine) in three commercial mould cheeses from three different producers from the area of the Central Europe during 8-week storage in refrigerator at 6 +/- 2 degrees C. The analysis of biogenic amines was made every week during 8-week of storage. Biogenic amines were extracted from the mould cheese by diluted HCl and determined using ion-exchange chromatography with post-column ninhydrin detection. Spermidine, spermine, putrescine and cadaverine were detected in tested mould cheeses. Spermidine was quantitatively the most important biogenic amine in all samples. While spermidine was detected immediately after purchase of samples, the rest of detected biogenic amines were developed during storage. The amount of putrescine was mostly increased during storage while the concentration of spermidine was decreased during storage. However, after 8 weeks of storage all samples contained toxicologically insignificant concentrations of detected biogenic amines in comparison with EU legislation and scientific literature and can be considered to be safe for human health.

Monografie uceleně prezentuje poznatky z oblasti základních principů výroby tavených sýrů a zabývat se vybranými vlastnostmi a vlivy, které tento výrobek ovlivňují. Nejprve je podána charakteristika mléka a přírodních sýrů, které tvoří základní surovinu pro výrobu tavených sýrů. Uveden je rovněž přehled sortimentu tavených sýrů. Dále jsou popsány ostatní suroviny pro výrobu tavených sýrů, tradiční: tvaroh, mléčný tuk (máslo, smetana, popř. bezvodý mléčný tuk), krém (sýr již utavený), pitná voda, přísady ovlivňující barvu a chuť a tavicí soli, i ?nové? suroviny a přídatné látky, např. různé mléčné koncentráty (sušená syrovátka, sušená mléka o různé tučnosti, kasein a jeho soli, mléčné koprecipitáty, sérové bílkoviny, aj.) a suroviny, resp. přídatné látky nemléčného původu ? hydrokoloidy a emulgátory. Jsou uvedeny základní fyzikálně-chemické principy výroby tavených sýrů, včetně objasnění nutnosti přídavku tavicích solí, popř. látek s obdobnými účinky. Následně jsou charakterizovány látky tradičně využ, The monograph provides a comprehensive presentation of knowledge gained in the area of basic principles of processed cheese production and deals with selected properties and effects which can influence this product. Firstly, it covers the characteristics of milk and natural cheeses, which represent basic raw materials for processed cheese production. Also, the assortment of processed cheeses is illustrated. Furthermore, other ingredients for processed cheese production are described ? traditional ones: quark, dairy fat (butter, cream or anhydrous dairy fat), rework (cheese which has already been processed), drinking water, additives influencing colour and flavour, emulsifying salts and ?new? ingredients and additives, e.g. various dairy concentrates (powder whey, powder milk with a different fat content, casein and its salts, dairy coprecipitates, whey proteins, etc.) and raw materials or additives of non-dairy origin ? hydrocolloids and emulsifiers. Basic physically-chemical principles of processed

Cílem této studie byla detekce biogenních aminů u vybraných technologicky využívaných bakterií mléčného kvašení. Pro zjišťování pprodukce biogenních aminů byly použity tři metody (iontově-výměnná chromatografie, polymerázová řetězová reakce a kultivační metoda s pH indikátorem). Jako nejméně vhodná metoda pro detekci biogenních aminů byla vyhodnocena kultivace v dekarboxylačním médiu s pH indikátorem, a to z důvodu zvýšeného počtu falešně pozitivních výsledků. Pro detekci bakterií s dekarboxylázovou aktivitou lze tedy doporučit PCR nebo chromatografické metody (např. iontově-výměnnou chromatografii) nebo kombinaci obou metod., The aim of this paper was to study the biogenic amines (histamine, tyramine, putrescine, cadaverine, agmatine, spermine and spermidine) production of selected technological important lactic acid bacteria (strains of the genera Lactococcus, Lactobacillus and Streptococcus). Three methods (ion-exchange chromatography, PCR and cultivation method with pH indicator) were used. Within the 39 strains of lactic acid bacteria tested, the production of tyramine (formed by tyrosine decarboxylase) was detected in 8 strains (3 strains of Lactococcus lactis subsp. lactis, 3 strains of Lactococcus lactis subsp. cremoris, 1 strain of Streptococcus thermophilus and 1 strain of Lactobacillus delbrueckii subsp. bulgaricus). The other tested biogenic amines were not detected. Cultivation in decarboxylation broth seems to be the least accurate method for the detection of biogenic amines due to enhanced risk of false-positive reactions. Therefore, in order to detect bacteria producing biogenic amines, the combination of PCR and chromatographic methods (e.g. ion-exchange chromatography) can be recommended.

Sterilované hotové pokrmy jsou v České republice zatím využívány pro účely zabezpečení výživy pouze příslušníků Armády ČR a IZS. Další možností by mohlo být také zajištění výživy civilního obyvatelstva v krizových situacích. Cílem práce bylo tedy stanovit nutriční hodnotu vybraných sterilovaných hotových pokrmů na základě jejich surovinového složení a pomocí indexu esenciálních aminokyselin. Jednalo se o pokrmy Vepřové maso s mrkví a bramborem, Vepřový guláš s těstovinami a Pikantní rizoto. Bylo zjištěno, že Vepřový guláš s těstovinami poskytuje 2097 kJ/ 300 g, Pikantní rizoto 2073 kJ/300 g a Vepřové maso s mrkví a bramborem jen 1474 kJ/300 g. Nejvyšší nutriční hodnotu podle EAAI má Vepřový guláš s těstovinami (81,13), následuje Pikantní rizoto (74,28) a Vepřové maso s mrkví a bramborem (73,50)., Ready to eat entrées are used only by Czech Army and Integrated rescue system to provide nutrition requires for their members. These meals can be used also for nutrition of civilian in crisis. The aim of the study was to determine the nutrition value of chosen ready to eat entrées by means of the index of essential amino-acids. It was found out that Pork goulash with pasta provides 2097 kJ/ 300 g, Spicy risotto 2073 kJ/300 g and Pork meat with carrot and potatoes 1474 kJ/300 g. The highest value of EAAI had Pork goulash with pasta (81,13), Spicy risotto (74,28) and Pork meat with carrot and potatoes (73,50).

Práce se zabývá hydrolyzačními křivkami pro 15 aminokyselin v kaseinu kravského mléka a modelových tavených sýrech s 30, 45 a 60 % tuku v sušině. Byl rovněž sledován vliv různého obsahu tuku na hydrolyzační křivky aminokyselin. Obsah aminokyselin v hydrolyzátech byl stanoven pomocí iontově-výměnné chromatografie. Na základě hydrolyzačních křivek byly vypočteny korekční faktory s cílem zvýšit přesnost a spolehlivost stanovení jednotlivých aminokyselin. S rostoucím obsahem tuku ve vzorcích, rostly i korekční faktory pro většinu sledovaných aminokyselin. Nejvyšší korekční faktory byly stanoveny pro treonin, serin a tyrozin u modelových vzorků tavených sýrů s nejvyšším obsahem tuku v sušině., The aim of this study was to investigate the effect of various selected solid low-molecular cosolutes (D-glucose, D-fructose, D-galactose, lactose, saccharose; target concentrations in samples 1% w/w) on viscoelastic properties of model processed cheese (40% w/w dry matter and 50% w/w fat in dry matter) without and with pectin addition (target concentrations in final products: 0.2% w/w and 0.4% w/w, respectively). Dynamic oscillation rheometry with parallel plate geometry was used to evaluate the changes in viscoelastic properties of samples. All applied low-molecular cosolutes (1% w/w) decreased the firmness of processed cheese. The nature of cosolute was not significant, i.e. the firmness of final products was declined by various cosolutes to the similar level regardless of their (i) reducing or non-reducing ability; (ii) structure (mono- or disaccharide, aldose or ketose); or (iii) steric arrangement (comparison of two epimers ? D-glucose and D-galactose). The reduction of sample rigidity due to cosolute addition was observed in both cases, i.e. in processed cheese without and also with pectin.

Práce se zabývá hydrolyzačními křivkami pro 15 aminokyselin v kaseinu kravského mléka a modelových tavených sýrech s 30, 45 a 60 % tuku v sušině. Byl rovněž sledován vliv různého obsahu tuku na hydrolyzační křivky aminokyselin. Obsah aminokyselin v hydrolyzátech byl stanoven pomocí iontově-výměnné chromatografie. Na základě hydrolyzačních křivek byly vypočteny korekční faktory s cílem zvýšit přesnost a spolehlivost stanovení jednotlivých aminokyselin. S rostoucím obsahem tuku ve vzorcích, rostly i korekční faktory pro většinu sledovaných aminokyselin. Nejvyšší korekční faktory byly stanoveny pro treonin, serin a tyrozin u modelových vzorků tavených sýrů s nejvyšším obsahem tuku v sušině., The work deals with hydrolysis curves for 15 amino acids (aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, valine, isoleucine, leucine, phenylalanine, tyrosine, histidine, lysine and arginine) in bovine casein and in model processed cheeses with 30, 45 and 60% w/w fat in dry matter. The effect of a different fat content on hydrolysis curves of the amino acids was observed. The hydrolysis curves were obtained by means of nonlinear regression using 13 hydrolysis intervals (range, 0?144 hours). The amino acid content in hydrolysates was measured using ion exchange chromatography. Correction factors were calculated with the aim of increasing the accuracy of the amino acid determinations. With the rising fat content in samples, the correction factors were increasing for the majority of amino acids observed. The highest correction factors were determined for threonine, serine and tyrosine.

The aim of our study was to assess the nutritional value of whole and dehulled ground seeds of Lupinus albus L., cv. Butan by the determination of balance digestibility of nutrients in growing pigs at different levels of replacement of soy protein with lupine. The experiment was performed on 25 pigs of hybrid combination Pietrain × (Duroc × Large White × Landrace) with initial body weights of 30.7 ± 2.21 kg. The feed compound of the control group contained extracted soybean meal (ESM). In four experimental diets, 50% and 100% replacement of soy protein with the inclusion of whole (WL 50, WL 100) or dehulled (DL 50, DL 100) lupine was carried out. Nutrient and amino acid digestibility was determined using the indicator of insoluble ash in 4M HCl in pigs with a mean live body weight of 48.9 ± 3.51 kg . Higher digestibility of crude protein (P < 0.01), ether extract (P < 0.01), crude fibre (P < 0.01), NDF, ADF (P < 0.05), and cellulose (P < 0.05) was found for the diet WL 50 compared with the control group ESM. In the diet DL 50, higher digestibility of crude protein, ether extract, crude fibre, NDF, and cellulose (P < 0.01) was recorded compared with the control. Higher digestibility of lysine and threonine (P < 0.01) was found in the diet WL 50 in comparison with ESM; a lower digestibility of methionine (P < 0.01) was found in the diet DL 50. Lower digestibility of crude protein, NDF, ADF (P < 0.01), and cellulose (P < 0.01) was found at 100% supplementation of soy protein with whole seed lupine (WL 100) compared to the control. A 100% replacement of soy protein with dehulled lupine (DL 100) resulted in significantly higher digestibility of dry matter (P < 0.01), crude protein (P < 0.05), ether extract (P < 0.01), crude fibre (P < 0.01), N-FE (P < 0.01), organic matter (P < 0.01), NDF (P < 0.01), ADF, and cellulose (P < 0.01) compared with the control diet. In this case, digestibility of threonine (P < 0.01) and lysine was higher, that of methionine was lower. The hi

Byl zkoumán vliv přídavku pektinu na viskoelastické a senzorické vlastnosti modelových tavených sýrů. Byla provedena dynamická oscilační reometrie, senzorická analýza a základní chemická analýza vzorků. Pektin způsobil zvýšení tuhosti vzorků. Senzorická hodnota tavených sýrů nebyla přídavkem pektinu zhoršena., The effect of pectin addition on viscoelastic properties of model processed cheeses with 40% w/w dry matter and 50% w/w fat in dry matter after 42 days of storage at temperature 6?2 °C has been investigated using dynamic oscillation rheometry (plate-plate geometry, frequency range 0.1?50.0 Hz; temperature 20°C). The role of pectin concentration (0.2, 0.4, 0.6 and 0.8% w/w) has been studied. Also, the sensory evaluation of samples has been made to assess cheese appearance, rigidity, spreadability and flavour. All samples with the pectin addition were more rigid and less spreadable compared to processed cheeses without pectin. With the increasing concentration of pectin the storage (G´) and loss (G´´) moduli rose at the whole tested frequency range (0.1?50.0 Hz). Growing pectin content resulted in the decrease in loss tangent (the nature of gel was changed to more elastic material). The dependence of processed cheese rigidity on pectin concentration (in range 0?0.8% w/w) was not linear. The appearance and flavour were not worse by pectin addition.