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

A previously developed method of HPLC-DAD-Fl has been used for the determination of phytochemical profiles in different types of drinks: instant coffee, soft drinks, energy drinks, and different types of tea (green, white, black, and red tea). Using data on the concentrations of 20 main phytochemicals (phenolic acids, flavan-3-ols, flavonols, flavones, and alkaloids) it was possible to identify most of the sample types. Chlorogenic and caffeic acids, and caffeine are the main target compounds in instant coffee; in soft and energy drinks, only caffeine was found. Tea has a more complex phytochemical composition. Unfermented tea is mainly composed of flavan-3-ols and alkaloids, with a high caffeine concentration. Black tea is composed of alkaloids and low levels of flavan-3-ols, which are affected by oxidative reactions during the fermentation. Flavonols are present in lower concentrations in all kinds of teas. The identified phytochemical distribution patterns were used to correctly differentiate instant coffee, soft drinks, energy drinks, unfermented tea and fermented tea (within fermented tea, black tea from red tea can also be differentiated).

The growth behaviour of foodborne pathogens (Staphylococcus aureus, Listeria monocytogenes, E. coli O157:H7 and Salmonella spp.) was investigated in pasteurised camel milk and compared with pasteurised bovine milk at different incubation temperatures. This study also aimed to compare the growth patterns of these four foodborne pathogens in pasteurised and raw camel milk. Pasteurised or raw camel milk and pasteurised bovine milk were separately inoculated with a cocktail of three strains of each foodborne pathogen. The inoculated milk samples were incubated at 10, 25, and 37°C. The total bacterial count (TBC) in raw milk and the total thermoduric bacteria count (TDB) in pasteurised milk samples were monitored. Greater growth inhibition rates of four pathogens were obtained for the pasteurised camel milk compared to the pasteurised bovine milk. Raw and pasteurised camel milk exerted bacteriostatic effect against all tested pathogens, particularly for the first 8 h of incubation in milk at the different temperatures. Pasteurised camel milk exerted an inhibitory activity that was equivalent to that of raw camel milk.

Antioxidant activities and free radical-mediated DNA strand breakages of five hydroxycinnamic acids were examined. Kinetic analysis of a stable galvinoxy (GO*)-scavenging reaction of hydroxycinnamic acids demonstrated that the molecular structure and the reaction medium were two important factors affecting the antioxidant mechanism and activity. In methanol, the kinetic process of the compounds, which have electron-donating groups (-OH, -OCH₃) in the ortho- or para-position of 4-OH, was primarily governed by the sequential proton loss electron transfer (SPLET mechanism). While, in ethyl acetate, the reaction mechanism is predominantly direct hydrogen atom transfer (HAT mechanism). But for the compounds having only one hydroxyl, both in ethyl acetate and methanol, the reaction mechanism is only HAT. At the same time, the compound bearing o-diphenoxyl is not the most active one in our tested environment.

Whole grain cereals such as oats are important sources of phenolic compounds. Oats contain phenolic amides, also named avenanthramides (AVAs), which have beneficial health properties because of their antioxidant, anti-inflammatory, and antiproliferative effects. The most common avenanthramides are esters of 5-hydroxyanthranilic acid with p-coumaric (AVA-A), ferulic (AVA-B), or caffeic (AVA-C) acids. The studies related to the stability of AVAs showed that AVA-B is sensitive to alkaline and neutral conditions and this sensitivity increases with higher temperatures. However, has been reported that AVA-A and AVA -C are more stable under the same conditions (alkaline and neutral conditions), and in addition that AVAs content of oats is increasing significantly with the germination process. AVAs help in preventing free radicals from damaging LDL cholesterol while AVAs-enriched extract of oats combined with vitamin C synergistically inhibited LDL oxidation in vitro. Both animal studies and human clinical trials confirmed that oats antioxidants have the potential of reducing cardiovascular risks by lowering serum cholesterol and inhibiting LDL oxidation and peroxidation. Therefore, the consumption of oats and products thereof is extremely important in reducing the risk of cardiovascular diseases.

In total 228 enterococci strains isolated from food were studied. Enterococcus faecalis, E. faecium, and E. casseliflavus were found to be the dominant strains while E. durans and E. mundtii were present in a smaller extent. Antimicrobial activity determined by double layer technique revealed that 150 (65.7%) strains showed antimicrobial activity against the individual tested pathogenic strains of Listeria monocytogenes, Staphylococcus aureus, and methicilin resistant S. aureus (MRSA). Cell-free neutralised supernatants (CFNS) were prepared from 150 potential bacteriocin producers. Of these 150, CFNS 107 (71.3%) strains were active in the bacteriocin production against one or more pathogenic strains tested. S. aureus and MRSA were found to be more sensitive to the antimicrobial substances than L. monocytogenes. Multiplex PCR for the detection of seven virulence genes in bacteriocin producing strains showed that 47.6% of strains were able to amplify one or more virulence genes. E. faecalis was the most virulent species. The presence of tyrdc gene was seen in all bacteriocin producing strains. None of the strains carried genes encoding the resistance to vancomycin.

Toxic metals (cadmium, lead, and mercury) in the tissues of common carp fished from three reservoirs (Pilská, Domaninský, and Matějovský) in the Bohemian-Moravian Highlands were measured in the period from April 2013 to September 2014 and the risk of consuming the fish from these localities was evaluated. During this project 25 fish specimens from each locality were analysed. The concentration of metals in muscle tissue and liver was determined by atomic absorption spectrometry. A variation in the content of heavy metals in fish samples and fish tissues was demonstrated and discussed. Higher concentrations of cadmium in the fish tissue were found in 50 samples of carp liver. Because the fish liver is not commonly consumed, common carp from the Moravian-Moravian Highlands does not pose any health risk for consumers. Concentrations of the other monitored toxic metals in fish tissue were low and were complying with the maximum residue limit in all cases.

Potential application of a metal oxide semiconductor based electronic nose (e-nose) as a non-destructive instrument for monitoring the change in volatile production of banana during the ripening process was studied. The proposed e-nose does not need any advanced or expensive laboratory equipment and proved to be reliable in recording meaningful differences between ripening stages. Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA), Soft Independent Modelling of Class Analogy (SIMCA) and Support Vector Machines (SVM) techniques were used for this purpose. Results showed that the proposed e-nose can distinguish between different ripening stages. The e-nose was able to detect a clear difference in the aroma fingerprint of banana when using SVM analysis compared with PCA and LDA, SIMCA analysis. Using SVM analysis, it was possible to differentiate and to classify the different banana ripening stages, and this method was able to classify 98.66% of the total samples in each respective group. Sensor array capabilities in the classification of ripening stages using loading analysis and SVM and SIMCA were also investigated, which leads to develop the application of a specific e-nose system by applying the most effective sensors or ignoring the redundant sensors.

The effect of curd cooking temperature (40 and 42°C), pressing, and ripening on textural and sensory properties of vacuum packaged semi-cooked ewe's milk cheese was studied. Chemical and microbiological analyses, colour, texture, and sensory characteristics were determined. Curd cooking temperature and pressing influenced a_w, moisture and salt-in-moisture content. Texture parameters were partially modified by pressing. On the contrary, cooking temperature resulted mainly in changes of cheese colour. Storage time was the most important factor in changing cheese characteristics, including sensory characteristics, whereas an increase of bitter aftertaste was observed during storage, likely due to packaging in a plastic pouch.

The water of the breads was replaced with phenolic aqueous extracts from chicory, cabbage, celery, fennel, olive leaf, or grape marc wastes obtained through microwave-assisted extraction. The highest phenolic concentrations were found in the grape marc and in the bread enriched with it. The highest antioxidant activity values were measured in the crust of bread produced with the grape marc extract and in the crumb of bread with olive leaf extract. Generally, the replacement of water caused significant decreases of the specific volume, the shift of the crumb colour towards redder and yellower tones, and modification of gustatory and tactile attributes.

We present a successful use of the plasmid inhibition detection and DNA isolation protocol optimisation for four food/feed samples in qPCR analysis of the sequence coding for chloroplast tRNA-Leu: two meat meal samples and two samples made of cranberries (jam and dried fruit). The quantitative real-time polymerase chain reaction (qPCR) can be inhibited by various substances and the DNA content in the sample can be underestimated. It is necessary to identify the PCR inhibition and choose an optimal DNA isolation protocol to correctly evaluate the sample. In a previous study, we have developed an assay using plasmid DNA carrying a non-homologous random sequence identifying possible inhibitors in qPCR in food/feed samples. The plasmid assay allowed to effectively reveal the PCR inhibition in all of the different sample matrices and to choose an optimal DNA isolation protocol.

Increased detection records of Listeria monocytogenes in foods have been recently observed. Standard methods of L. monocytogenes elimination from food products including pasteurisation or acidification may, however, be unreliable. The elimination of L. monocytogenes using specific bacteriophages which are natural antagonists of these pathogenic bacteria has become an innovative method that does not affect the taste, smell or appearance of the product. The use of phage preparations in food production is becoming an increasingly popular method for the effective and safe elimination of L. monocytogenes from food products.

Within the framework of the research project ELISA methods for the quantitative determination of allergenic substances in foodstuff and raw materials were developed. ELISA kits for allergenic proteins of milk (casein, beta-lactoglobulin and BSA) egg white proteins and mustard proteins were validated and collaborative studies were performed to prove the validation of the ELISA methods developed. Various methods of extraction were tested. The parameters as a limit of detection, as a limit of quantification, robustness, repeatability and accuracy were determined. A broad range of zero matrices for allergens were tested as well. The ELISA kits are suitable for the determination of allergens according to EU legislation Directive 2005/26/EC and Directive 2006/142/EC in the laboratories focused on this topic.

Recycled paper is commonly used in food packaging industry, especially for disposable products. The material coming into direct contact with food products must not represent a source of contamination for food in accordance with the Framework Regulation (EC) No. 1935/2004 containing the general requirements on all food contact materials. In the present study, the microbial purity of 31 paper-based materials with different contents of recycled matter (0-100%) was evaluated using a standard method based on the disintegration of paper. The results of the present study indicate the existing relation between the use of recycled fibers and the content of microorganisms. The increased amount of recycled fibers significantly increased the amount of bacteria in the paper samples. The highest content of microorganisms was observed in the case of paper with the highest recycled fiber content. Total counts of bacteria ranged from 5.0 × 10¹ to 1.2 × 10⁵ CFU/g. Moulds were detected only in three paper samples. As the microorganisms present in food packaging may penetrate into foodstuffs (particularly those with high contents of water or fat) and have an adverse effect on end-consumers' health, microbial criteria for food packaging should be included into the EU legislation.

Barley primarily serves as a major animal feed crop; smaller amounts of barley are used in health foods and in the malting process. Detailed geometric parameters of kernels are very important for the design of food engineering processes, such as the air transport, drying, milling, and malting. Image analysis was used to determine the size parameters of one hundred kernels of selected varieties of Hordeum vulgare L. The data for every kernel captured were stored for further use, together with the mean, standard deviation (SD), coefficient of variation (CV), and images themselves. The measured data were then used to compute the volume and surface area of each of the five kernel models (Models 0-4), the results being subsequently verified by pycnometric measurement. Model 0 represents the general ellipsoid, models 1-3 various combinations of two parts of a general ellipsoid with one or two cone frustums. The best fitted model 4 was a combination of two cone frustums. Based on the results of image analysis measurements and on the presented model 4, a simplified method for the specific surface estimation of barley grains from the weight of 1000 kernels is recommended.

A unique project exists in the Czech Republic, namely the Czech National Programme of Protection of Genetic Resources of Economically Significant Microorganisms and Tiny Animals (NPPGR), which includes nineteen Czech collections of microorganisms (bacteria, fungi), viruses, and tiny animals. It is fully financed by the Ministry of Agriculture of the Czech Republic. Under this Programme, the Culture Collection of Fungi (CCF) in Prague maintains 293 fungal strains, 225 of which are food and feed relevant fungi (e.g. toxigenic Aspergillus flavus, Penicillium verrucosum, and Fusarium sporotrichioides). The main aims of the Programme are to provide adequate protection of the microbial genetic resources that are of importance to the agriculture and food industries, to provide strains (free of charge) for the research and educational purposes, and to support the cooperation between Czech and foreign institutions. A database of all microorganisms is accessible online.

A method for the rapid and nondestructive determination of total nitrogen content in soy sauce was explored. Prediction models were established using near-infrared spectroscopy combined with each of the following techniques: partial least squares (PLS), interval PLS, synergy interval PLS (siPLS), and backward interval PLS. Results showed that each improved forecast model was better than the PLS model. The siPLS method exhibited the best performance. The full spectrum of light soy sauce was divided into 20 subintervals. The combination of four subintervals, namely, 6, 11, 13, and 18, showed the best effect, with a correlation coefficient of 0.9977 and an RMSECV of 0.0198. The full spectrum of dark soy sauce was divided into 20 subintervals. The combination of three subintervals, namely, 14, 17, and 19, showed the best effect, with a correlation coefficient of 0.9818 and an RMSECV of 0.0640. Therefore, the siPLS method can realise a rapid and accurate detection of total nitrogen content in soy sauce.

The fucoidans were obtained by extraction with water and gradient precipitation with different concentrations of ethanol. The main structural characterisations and bioactivities were achieved. Four fractions of water-soluble crude fucoidans with different molecular weights - SPC60, SPC70, SPH60, SPH70 - were extracted from S. pallidum collected from the Yellow Sea, China, using cold water and hot water extraction, and fractional precipitation with gradient concentrations of ethanol. Chemical analysis demonstrated that all of these fucoidan fractions consisted of fucose, rhamnose, xylose, mannose, glucose, and galactose with different monosaccharide mole ratios. Fractions SPC60, SPC70, and SPH70 showed moderate cytotoxic activity against P388 murine leukaemia cells. Fucoidan is a kind of bioactive polysaccharide from the brown algae. This study provides a fast and feasible method to obtain fucoidans from S. pallidum, which can be used as pharmaceutical material and functional food.

Epifluorescence microscopy (EFM) was used to study the biofilm formation of Pseudomonas aeruginosa after 6, 24, 30, 48, 54, 72, 78, and 96 h growth in a chamber slide system. For this purpose, the biofilm was stained with the Live/Dead BacLight, wherein live and dead cells were visualised based on the cell membrane integrity. With the use of EFM we described 8- of 9-stage biofilm characteristics after 78 h of growth, since the majority of microscopic fields were fully covered with attached cells. However, the 96-h growth resulted in the cell detachment and revealed 30% of dead cells of all those cells that remained on the surface. The susceptibility testing of planktonic and biofilm cells to two disinfectants, chlorine-based and quaternary ammonium compound-based, revealed that biofilm cells were more tolerant to a chlorine-based sanitiser than planktonic counterparts. P. aeruginosa was inhibited by lower concentrations of the quaternary ammonium compound-based sanitiser than the chlorine-based sanitiser, which on the other hand was more effective in cell inactivation, as both the MIC/MBC (inhibitory/bactericidal) measurement and the CFDA/PI (carboxyfluorescein diacetate/propidium iodide) staining indicated.

The results of chemical and microbial analyses of raw milk samples coming from organic and conventional farming systems were statistically compared. The samples were analysed during a twelve-month period (June-May). A total of 2206 samples were collected of which 528 were organic. After raw milk was processed, sensory hedonic quality of 171 pairs of organic and conventional non-standardised pasteurised whole milk samples were evaluated using the pair comparison preference test. Four parameters in raw milk, free fatty acids, urea content, somatic cell count and coliform bacteria count, showed no significant differences between the two types of production. Significantly higher contents of protein, casein, lactose, and non-fat solids were detected in conventional milk, which also had a significantly lower freezing point. On the contrary, significantly higher contents of total mesophilic bacteria count and a higher percentage of samples with positive coliform bacteria count were found in organic milk samples. Sensory analysis of pasteurised milk showed no significant hedonic difference between organic and conventional samples.

The urea complexation was used to concentrate n-3 fatty acids (FA) from crude and refined commercial salmon oils. The experimental procedure included salmon oil saponification, free fatty acid (FFA) collection, formation of urea-FFA inclusion complexes, extraction of free n-3 FA and further analysis by gas-liquid chromatography of the corresponding FA methyl esters. Differences between crude and refined salmon oil could be observed. Crude oil provided higher typical odour, viscosity and suspension particle values, whereas crude salmon oil showed higher FFA and impurities content while p-anisidine and iodine values, moisture content and formation of conjugated dienes and trienes did not provide any significant differences between both oils; refined oil showed lower a* and b* scores when compared to its counterpart crude oil. Related to the n-3 PUFA concentration, a decrease in saturated fatty acids C 14:0, C 16:0, and C 18:0 and monounsaturated fatty acids C 18:1 9c, and C 18:1 11c, as well as a high yield of n-3 PUFA, EPA+DHA and total PUFA recovering could be observed starting from both crude and refined oils, which confirmed salmon oil to be a profitable source of such highly valuable constituents. Factors such as reaction temperature and ureaFFA ratio showed to be markedly significant to achieve higher value concentrations.

Extra-virgin oil is obtained from olive fruits only by mechanical means. The quality of extra-virgin olive oils is affected mainly by hydrolytic and oxidative reactions. For this reason, the commercial shelf-life is usually no longer than 18 months. In order to investigate the effects of a prolonged storage, olives from cv. Coratina were crushed using a three phase system to produce extra virgin olive oil analysed for sensory and chemical-physical indices, phenolic profile, tocopherol content, and antioxidant activity during a 8-years storage. The oil lost its characteristics of extra-virgin after 6 years of storage, time at which the median of the defects was higher than 0 and free acidity exceeded the limit fixed for this category by the European Regulation whereas the stability against oxidation persisted for a longer period due to the high concentration of oleuropein derivatives. A strong positive linear correlation was observed between the phenolic content and antioxidant activity measured according to the ABTS^+. to indicate a noticeable radical scavenging ability of phenolic compounds.

We evaluated the effects of Gymnorhynchus gigas on the freshness and hygienic quality of Lepidopus caudatus. Total Volatile Basic Nitrogen (TVB-N), Trimethylamine Nitrogen (TMA-N), as well as Specific Spoilage Organisms (SSOs) are the most important freshness indicators in fish. Our study was carried-out on 65 specimens of L. caudatus kept in ice and stored at 2°C for different period of time. The microbiological charge of SSOs recovered on a portion of parasitised muscles (MP) was compared with those recovered on portions of parasite-free muscles (M). The contents of TVB-N and TMA-N on MP, M, and G. gigas larva/ae were measured using the Conway microdiffusion method. High prevalence (72.31%) of G. gigas in the specimens of L. caudatus from the Mediterranean sea was observed. No statistically significant differences (P < 0.05) between M and MP were found during storage. However, massive infestation of G. gigas on the muscle of the silver scabbardfish could negatively influence TVB-N values, without compromising the sensorial characteristic of fish.

Cooking and drying conditions of the shea butter extraction process were determined using a response surface methodology. The influence of cooking time, temperature, and nuts/water mass ratio, drying time, and temperature on the content of free fatty acids, the peroxide value, as well as on the extraction yield was investigated. Results showed that both the free fatty acid content and the peroxide value were significantly affected by cooking and drying temperature; the cooking time and nuts/water ratio also affected significantly the peroxide value. Increasing cooking and drying temperature reduced the FFA content but contributed to increase the peroxide value. The cooking and drying temperature range of 75-80°C and < 54°C, respectively; cooking time of 70-100 min; drying time < 40 h, and cooking nuts/water mass ratio < 400 g/l of water were found to be optimum conditions for the extraction of shea butter.

High performance liquid chromatography (HPLC) method with the pre-column derivatisation by AccQ*Tag agent and following determination of these derivates after their separation in reverse phase column followed by fluorescent detection was used for the determination of amino acids in cheeses. The contents of sixteen free amino acids in twenty five cheeses commercially available in the Czech Republic were measured. The total content of free amino acids in the studied cheeses varied in the range from 27 g/kg to 160 g/kg. Among individual amino acids, seven amino acids were more concentrated in all cheese samples and came from three distinctive taste groups: bitter tasting amino acids (leucine, lysine, and phenylalanine), bitter sweet amino acids (proline and valine), and salty-umami amino acids (glutamic acid and aspartic acid). The differences in the contents of the total and individual free amino acids were influenced by the kind of cheese and mainly by the duration and intensity of proteolysis.

The content of free SO₂ (1.3-37.9 mg/l and 5.3-19.7 mg/l for 2009 and 2010) and total SO₂ (38.3-272.0 mg/l and 52.0-102.1 mg/l for 2009 and 2010) for individual wines was in a broad interval. Results of free SO₂ found using the commercial SO₂ reagent were higher than our results since the reagent determined not only free SO₂ but also reductones. The content of titrated acids was constant with a very moderate time decrease and the values were on average about 9.1-5.3 g/l (2009) and 13.1-7.9 g/l (2010). Similarly, the content of tartaric acid was nearly constant and the values were on average about 2.37-1.47 g/l (2009) and 6.65-2.69 g/l (2010). The percentage ratio of tartaric acid in the content of titrated acids is also constant (average 24.39%-38.6% for individual wines).

We determine the effects of the technology of obtaining potato protein preparation and of different variants of enzymatic hydrolysis on the chemical and amino acid compositions of the hydrolysates obtained. Potato protein concentrates obtained through their thermal coagulation in potato juice with calcium chloride, calcium lactate or without salt addition were subjected to enzymatic hydrolysis using two commercial hydrolytic enzymes: endopeptidase (Alcalase) and exopeptidase (Flavourzyme). Chemical (contents of ash, total and coagulable protein) and amino acid compositions of the hydrolysates obtained were determined. On the ground of the findings it was stated that the type of potato protein preparation used and conditions of enzymatic modification influenced on the properties of the hydrolysates obtained. Preparations obtained during the study were characterised by similar chemical and amino acid compositions, whereas the preparation obtained through thermal coagulation with the use of calcium lactate contained insignificantly more protein and essential amino acids. The least liable to enzymatic hydrolysis was the preparation obtained by using calcium chloride, particularly when only endopeptidase was used. The application of endopeptidase enzyme enabled to obtain 60% of proteolysis efficiency and the addition of the second enzyme (exopeptidase) to the protein solution insignificantly increased the proteolysis efficiency (to ca 70%), mainly when the preparation coagulated with the use of calcium chloride was hydrolysed. Proteolysis of the protein preparations obtained with the use of two enzymes was more favourable, particularly due to the quantity of free amino acids in and amino acids composition of the hydrolysates.

The ability of phenolic acids (gallic, gentisic, protocatechuic, syringic, vanillic, ferulic, caffeic, and sinapic; 600 mg/kg) to protect α-tocopherol was tested during the heating of sunflower oil on a hot plate set at 180°C and was compared with the ability of these phenolic acids to slow down the formation of polymerised triacylglycerols (TAG) in the same conditions. The half-life of α-tocopherol (calculated as the time needed for the α-tocopherol content to decrease to 50% of the original value) was extended significantly by gentisic, caffeic, and gallic acids (from 1.16 h to 1.77 h, 1.78 h, and 2.26 h, respectively), while the formation of polymerised TAG was slightly suppressed only by gallic acid.

The present study has been done in order to determine the risks inherent in the milk production in Turkey. For that objective, factors such as the milk yield, the gross revenues realised, and the price levels as reflected to the producer's benefits, have been taken into account. Upon the calculation of the measures for variables, fluctuations were found in the milk yield, prices, and gross revenues. Based on the hypothesis that the information possessed by the producer on the economic and technological developments is scarce and restrained, the variable coefficient has been calculated as 10.81% for yield, 23.26% for prices, and 30.01% for gross revenues, respectively. With the hypothesis that the producers are aware of and informed on the economic and technological developments, these ratios, that is to say, the fortuitous variable coefficients would be, respectively, 2.07%, 15.96%, and 16.07%. According to the conclusions reached, an environment in which the producers can take rational decisions concerning the milk production can be said not to exist. For this reason, the government intervention through efficient measures for the dairy production will be necessary. Furthermore, the producers should be given informational support through the published studies in the agricultural extension.

The aim of this work was to characterise influence of whey proteins-pectin interaction on emulsification properties of whey. As the first, structural characteristics of pectin-protein complexes were evaluated for pure β-lactoglobulin by both dynamic light scattering method for measuring of the particle size distributions and Doppler laser electrophoresis for measuring the ξ-potential (surface electrical potential) of particles. In mixed pectin-β--lactoglobulin systems, it was observed that the addition of pectin prevent from the protein-protein interaction, which caused production of huge protein aggregates (2000-2500 nm) at pH values near β--lactoglobulin isoelectric point and at temperatures near its denaturation temperature. However, these protei-pectin complexes had large hydrodynamic diameters (monomodal size distribution at 350 and 1000 nm for high esterified and low esterified amidated pectin, resp.), which can slow down their diffusion to the oil-water interface in emulsions. The ξ -potential values indicated improvement of colloid stability by addition of pectin. The evaluation of the influence of the protein-pectin interaction on emulsification properties was performed by the determination of a surface weighted mean (D [3,2]) of oil droplets in o/w emulsions measured by the laser diffraction, further by microscope observations, the determination of emulsion free oil content and observations of creaming. The emulsifying properties were influenced by the pectin addition, more negatively by the high esterified than by the low esterified amidated pectin addition.