The viscosity of processed cheese sauces depending on addition type and concentration of 1-monoglycerides

The aim of this work was to study viscosity of processed cheese sauces with 1-monoglycerides (MAG) addition. Six types of 1-monoglycerides (1-monocaprin, C10:0; 1-monolaurin, C12:0; 1-monomyristin, C14:0; 1-monopalmitin, C16:0; 1-monostearin, C18:0; 1-monoolein, C18:1) in concentration of 0.25 and 0.50% w/w were used. Control samples were prepared without MAG but with lecithin. The lowest values of viscosity were found in control samples. The viscosity increased with extending of chain fatty acid in the molecule of monoglycerides. The highest viscosity was found in samples with 1-monomyristin

Structural model for the multisubunit Type IC restriction–modification DNA methyltransferase M.EcoR124I in complex with DNA

Recent publication of crystal structures for the putative DNA-binding subunits (HsdS) of the functionally uncharacterized Type I restriction–modification (R-M) enzymes MjaXIP and MgeORF438 have provided a convenient structural template for analysis of the more extensively characterized members of this interesting family of multisubunit molecular motors. Here, we present a structural model of the Type IC M.EcoR124I DNA methyltransferase (MTase), comprising the HsdS subunit, two HsdM subunits, the cofactor AdoMet and the substrate DNA molecule. The structure was obtained by docking models of individual subunits generated by fold-recognition and comparative modelling, followed by optimization of inter-subunit contacts by energy minimization. The model of M.EcoR124I has allowed identification of a number of functionally important residues that appear to be involved in DNA-binding. In addition, we have mapped onto the model the location of several new mutations of the hsdS gene of M.EcoR124I that were produced by misincorporation mutagenesis within the central conserved region of hsdS, we have mapped all previously identified DNA-binding mutants of TRD2 and produced a detailed analysis of the location of surface-modifiable lysines. The model structure, together with location of the mutant residues, provides a better background on which to study protein–protein and protein–DNA interactions in Type I R-M systems

Structural model for the multisubunit Type IC restriction–modification DNA methyltransferase M.EcoR124I in complex with DNA

Recent publication of crystal structures for the putative DNA-binding subunits (HsdS) of the functionally uncharacterized Type I restriction–modification (R-M) enzymes MjaXIP and MgeORF438 have provided a convenient structural template for analysis of the more extensively characterized members of this interesting family of multisubunit molecular motors. Here, we present a structural model of the Type IC M.EcoR124I DNA methyltransferase (MTase), comprising the HsdS subunit, two HsdM subunits, the cofactor AdoMet and the substrate DNA molecule. The structure was obtained by docking models of individual subunits generated by fold-recognition and comparative modelling, followed by optimization of inter-subunit contacts by energy minimization. The model of M.EcoR124I has allowed identification of a number of functionally important residues that appear to be involved in DNA-binding. In addition, we have mapped onto the model the location of several new mutations of the hsdS gene of M.EcoR124I that were produced by misincorporation mutagenesis within the central conserved region of hsdS, we have mapped all previously identified DNA-binding mutants of TRD2 and produced a detailed analysis of the location of surface-modifiable lysines. The model structure, together with location of the mutant residues, provides a better background on which to study protein–protein and protein–DNA interactions in Type I R-M systems

A RecB-family nuclease motif in the Type I restriction endonuclease EcoR124I

The Type I restriction-modification enzyme EcoR124I is an ATP-dependent endonuclease that uses dsDNA translocation to locate and cleave distant non-specific DNA sites. Bioinformatic analysis of the HsdR subunits of EcoR124I and related Type I enzymes showed that in addition to the principal PD-(E/D)xK Motifs, I, II and III, a QxxxY motif is also present that is characteristic of RecB-family nucleases. The QxxxY motif resides immediately C-terminal to Motif III within a region of predicted α-helix. Using mutagenesis, we examined the role of the Q and Y residues in DNA binding, translocation and cleavage. Roles for the QxxxY motif in coordinating the catalytic residues or in stabilizing the nuclease domain on the DNA are discussed

Fuzzy and regression approach to estimating the cheese consistency changes influenced by a substitution of emulsifying agents in the mixture

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

Estimation of the effect of the combinations of sodium phosphates on hardness of the model processed cheese by fuzzy logics

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 effect of three different ripening/storage conditions on the distribution of selected parameters in individual parts of Dutch-type cheese

P>The aim of the study was (i) to detect changes of dry matter, NaCl and twenty-two free amino acids contents, pH and levels of selected microorganisms in four layers of cheese (from edge to core) during ripening and storage period and (ii) to describe the changes of the above-mentioned parameters caused by early relocation of cheese from optimum ripening conditions to refrigeration temperatures. The number of mesophilic aerobic and facultative anaerobic bacteria and lactic acid bacteria differed significantly (P < 0.05) during the experiment dependent on the analysed layer and ripening/storage conditions. The free amino acid content differed significantly in individual analysed layers of cheese and also according to individual ripening/storage conditions. The highest content of free amino acids was found in samples stored at optimal ripening temperatures. Cheese hardness was also analysed and the lowest one was detected in samples ripened under optimal temperatures for the whole period. Early release of cheeses into storage rooms with lower temperature significantly affected properties of these products

The effect of different ternary mixtures of sodium phosphates on hardness of processed cheese spreads

The aim of this study was to describe the dependence of hardness of processed cheeses on the proportion of disodium hydrogenphosphate (DSP), tetrasodium diphosphate (TSPP) and/or sodium salts of polyphosphate (POLY) in ternary mixtures of emulsifying salts. The samples were observed during a 30-day storage period (at 6°C). On the second day of storage, hardness of the samples with the individual DSP, TSPP or POLY were in the range of 1.65-1.83N, 2.42-2.81N and 5.98-6.53N, respectively. Within zero or a very low proportion of POLY in the mixture, hardness of the processed cheeses increased rapidly (up to 14N) at a specific ratio of DSP to TSPP in range of 1:1-3:4. Hardness of the samples containing the above-mentioned specific ratio was decreasing with the rising content of POLY (up to 60%) in the ternary mixtures. Within the prevailing content of POLY in the ternary mixtures (more than 60%), the phenomenon of a specific ratio of DSP to TSPP was no longer observed. With the increasing storage period (up to 30days), hardness of the processed cheeses was slightly rising (in range of 2-4N)

The effect of combinations of sodium phosphates in binary mixtures on selected texture parameters of processed cheese spreads

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 effect of ternary emulsifying salt composition and cheese maturity on the textural properties of processed cheese

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