bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in the physical properties of ultra high temperature processed buffalo milk during storage
Authors: Sharma Dinesh K. , Prasad Deoki N. 
Published: June 2009

SummaryBuffalo milk collected within 4 h of milking was standardized (4·5% fat and 8·5% SNF) and processed in an ultra high temperature plant at 5 °C intervals. Changes in viscosity, free tyrosine and sedimentation were measured over 6 months at 15 and 30 °C. We suggest that an interaction probably occurred in the casein and whey proteins (β-lactoglobulin) and caused changes in the physical and chemical qualities of these milks during storage. Variations in the casein particle sizes were observed in the milks during storage by electron microscopy.
A method for assessing loss in milk yield due to subclinical mastitis
Authors: Oshima Masaharu , Yoshida Tatsuyuki , Koyama Kohei , Moriyama Taminori 
Published: June 2009

SummaryA method for assessing the loss in quarter milk yield due to subclinical mastitis is proposed. It is based upon two indices calculated from quarter milk yields and results from the assessment of mastitis obtained by measurement of the electrical conductivity of milk. The results were obtained from the cows through repeated quarter-milkings during several months of lactation. The grade of abnormality of a quarter with subclinical mastitis was expressed by the first index, the mean quarter difference of electrical conductivity of milk produced by the quarter (mQdEC, 25 °C). The reduction in milk yield of a quarter presumed to be due to subclinical mastitis was expressed by another index, the quarter yield ratio, R, which is that percentage of normal milk yield produced by a quarter with mastitis. Examination of the relationship between these two indices showed that subclinical mastitis caused a reduction in milk yield in the affected quarters. From the linear regression, it was found that ~3% reduction in quarter milk yield occurred for every 1 x 10–4 S/cm increase in the mQdEC of the quarter with presumed subclinical mastitis.
Relationship between amplitude and phase measurements of photoacoustic signal in the infrared region and water concentration in condensed milk
Authors: Martel Richard , Paquin Paul , Bertrand Lionel 
Published: June 2009

SummaryPhotoacoustic signals in the near infrared region (~ 2·75 μm) have been investigated using amplitude and phase information to determine their effectiveness in estimating the water content of milk. The results obtained showed a good correlation between the photoacoustic signal and water concentration (R2 = 0·98) even though photoacoustic saturation was present in the range of wavelengths studied. However, this is not recommended as a fast technique for water determination because of inherent phase fluctuations in the samples analysed.
Effect of mastitis on plasminogen activator activity of milk somatic cells
Authors: Zachos Teffi , Politis Ioannis , Gorewit Ronald C. , Barbano David M. 
Published: June 2009

SummaryThis study was conducted to examine the effects of mastitis and stage of lactation on plasminogen activator (PA) activity in milk somatic cells. An assay System, which measures the plasmin-mediated hydrolysis of the chromogenic substrate D-valyl-leucyl-lysinep−nitroanilide, was used to assess PA activity present within milk somatic cells. Milk cell associated PA activity was increased (P< 0·05) by 50% in the presence of fibrin fragments. This suggests that milk somatic cells contain tissue PA which, unlike urokinase PA, is preferentially activated in the presence of fibrin fragments. An increase of the milk somatic cell count from < 5 × 104 to > 106cells/ml resulted in an 8-fold increase in PA activity per cell. Elevated levels of PA activity were associated with milk somatic cells isolated from mastitic quarters obtained from cows in early (<4 months in lactation) or late lactation (>8 months in lactation). We conclude that PA activity is increased during severe mastitic inflammation. Although the physiological function of this enzyme is as yet unclear, we propose that it may be involved in the conversion of plasminogen to plasmin, contributing to the higher levels of plasmin occurring in milk isolated from mastitic quarters.
Comparison of the ability to bind lipids ofβ-lactoglobulin and serum albumin of milk from ruminant and non-ruminant species
Authors: Pérez M. Dolores , Puyol Pilar , Ena José Manuel , Calvo Miguel 
Published: June 2009

SummaryThe interaction of sheep, horse, pig, human and guinea-pig whey proteins with fatty acids has been studied. Using gel filtration and autoradiography, it was found that sheepβ-lactoglobulin and serum albumin from all species had the ability to bind fatty acidsin vitro. Sheepβ-lactoglobulin, isolated from milk, had ˜ 0·5 mol fatty acids bound per mol monomer protein, and albumin from sheep, horse and pig contained ˜ 4·5, 2·9 and 4·7 mol fatty acids/mol protein respectively. However,β-lactoglobulin from horse and pig milk had neither fatty acids physiologically bound nor the ability to bind themin vitro. Albumin was the only whey protein detected with bound fatty acids in these species as well as in human and guinea pig. This suggests that the ability of ruminantβ-lactoglobulin to bind fatty acids was not shared by the same protein of non-ruminants.
Fractionation of whey protein components through a large pore size, hydrophilic, cellulosic membrane
Authors: Mehra Raj K. , Donnelly William J. 
Published: June 2009

SummaryWhey protein solutions of different chemical compositions were filtered through a large pore size ultrafiltration membrane (molecular mass cut-off 100 kDa). The influences of pH, ionic environment and Ca chelation on the performance characteristics of the membrane (filtration rate, total and individual whey protein permeability) were examined. Increase in pH in the range 5·0-10·0 resulted in a gradual increase in filtration rate and individual whey protein permeability. The presence of Ca in the whey protein solution had a negative effect on the performance characteristics of the membrane. Addition of EDTA to protein solution improved the filtration rate but had no effect on the protein permeation. Fractionation of the low molecular mass whey proteins (β-lactoglobulin and α-lactalbumin) from high molecular mass proteins (bovine serum albumin, lactoferrin and immunoglobulins) was best achieved at pH 8·0.
Purification and identification of TGF-β2-related growth factor from bovine colostrum
Authors: Tokuyama Yukiko , Tokuyama Haruhiko 
Published: June 2009

SummaryBovine colostrum contains transforming growth factor (TGF)-β-like activity. High levels of this activity are found in early colostrum (within 12 h after parturition); however, it decreases rapidly after 30 h. In this study, the activity in early colostrum was purified by a sequence of decaseination, DEAE-Sephacel chromatography, Sephadex G-100 gel filtration, precipitation at neutral pH, further gel filtration and reversed-phase FPLC. A homodimeric 23 kDa protein was identified that retained the TGF-β-like activity. Its activity was completely neutralized by a specific anti-TGF-β2 antibody. These results indicate that the TGF-β-like growth factor found in bovine colostrum is chemically and antigenically related to TGF-β2. The physiological roles of the TGF-β2-related growth factor are discussed.
Oscillatory rheological study of the gelation mechanism of whey protein concentrate solutions: effects of physicochemical variables on gel formation
Authors: Tang Qingnong , McCarthy Owen J. , Munro Peter A. 
Published: June 2009

SummaryThe thermal gelation of a commercially available whey protein concentrate was studied by oscillatory rheometry using a Bohlin rheometer. Gelation time increased with decreasing protein concentration with a critical protein concentration (at infinite gelation time) of 6·6%. The effect of temperature in the range 65–90 °C on gelation time was described by an Arrhenius equation with an activation energy of 154 kJ/mol. Gelation time was a minimum at pH 4–6, the isoelectric region of the whey proteins. Small additions of NaCl or CaCl2 dramatically decreased gelation time. Higher protein concentrations always produced higher storage modulus (G′) values after any heating time. Loss modulus (G″) v. time curves exhibited maxima at relatively short times for protein concentrations of 30 and 35%. G′ values for 10% protein concentration increased with temperature for heating times up to 59·5 min. G′ values at 59·5 min for 25% protein concentration were higher at 78 °C than at either 85 or 90 °C. The results are discussed in terms of current theories for biopolymer gelation.
Flow behaviour of low solids fresh cheeses
Authors: Korolczuk Jozef 
Published: June 2009

SummaryA computerized, coaxial cylinder viscometer, controlled by a function synthesizer, was used to study the stress characteristics of acid fresh cheeses containing 7·5–8·5% protein and 0–20% fat in total solids, as a function of shearing time (0–3600 s) and of shear rate (0–4·5 s–1). For a given shear rate the stress diminished with time, following an exponential equation. The hypothetical final stress level (Sf for the shearing time t = ∞) represented about half its initial value (Si). For four cheese samples, the time required for the stress to become equal to Sf + (Sf – Sf)/e was 340–560 s. The stress-shear rate relation indicated shear thinning behaviour. The effect of shearing time showed that the material was thixotropic. The cheeses exhibited plastic flow. The initial and final stress levels were hyperbolic functions of the shear rate. Bingham final yield stress (for t = ∞) was 14–50 Pa. It was 15–25% higher for increasing than for decreasing shear rate. Bingham viscosity (for t = ∞) was between 2 and 6 Pa s. It was 10–20% higher for decreasing shear rate. The initial level of Bingham viscosity was ˜ 30% higher than its final value.
Methods for the determination of aroma compounds in dairy products: a comparative study
Authors: Xanthopoulos Vassilis , Picque Daniel , Bassit Naïma , Boquien Clair-Yves , Corrieu Georges 
Published: June 2009

SummarySeveral methods used for sample preparation and for the determination of volatile flavour compounds in dairy products were tested. Steam distillation was an advantageous method for isolating volatile substances. The extraction yields for acetaldehyde, ethanol and diacetyl were >90%, and acetoin was partly separated from diacetyl. After steam distillation of the sample, gas-liquid chromatography was found to be a rapid method for the determination of acetaldehyde, ethanol and diacetyl in a wide range of concentrations corresponding to those found in dairy products. However, the lower limits for reproducible measurements were high (250, 1250 and 65 μM respectively). From the same sample, colorimetry was shown to be an accurate method for the detection of low levels of diacetyl and acetoin (12 and 57 μM respectively). Diacetyl interfered in the colorimetrie determination of acetoin. However, the interference was < 10% when the diacetyl: acetoin molar ratio was < 0·033. Dynamic head-space gas chromatography proved to be a sensitive method for acetaldehyde and diacetyl determination when a ‘purge and trap’ injector and a capillary column were used. The ranges suitable for determination lay between 25 and 100 μM for acetaldehyde and between 2·9 and 11·4 μM for diacetyl. Acetoin was analysed by HPLC on a cation-exchange column and detected by refractometry for concentrations ranging from 250 to 4000 μM.
Inhibitory effect of dairy products on the mutagenicities of chemicals and dietary mutagens
Authors: Cassand Pierrette , Abdelali Hasnaa , Bouley Christine , Denariaz Gerard , Narbonne Jean F. 
Published: June 2009

SummaryThe antimutagenic effects of uninoculated milk and milks cultured withBifidobacteriumorLactobacillusstrains towards the mutagenicity induced by two direct mutagens, 4-nitroquinolineN-oxide and 2-nitrofluorene, and three dietary indirect mutagens, aflatoxin B1, benzo(a)pyrene and quercetin, were investigated using thein vitro Salmonella typhimuriumtest. Each cultured milk sample and control milk had a significant antimutagenic effect, to an extent varying with the mutagen used. Uninoculated milk had a greater inhibitory effect than cultured milks towards dietary indirect mutagens.
Effect of yogurt feeding on the small and large intestine associated lymphoid cells in mice
Authors: Perdigón Gabriela , Rachid Mirta , De Budeguer Marta V. , Valdez Juan C. 
Published: June 2009

SummaryThe effect of giving yogurt supplements to Balb/c mice on the various gut-associated lymphoid cells was studied. Animals were fed for 2, 5, 7 and 10 consecutive days. The different lymphoid cell types were identified and counted by haematoxylin–eosin staining of histological slices. The numbers of cells secreting IgA, IgG and IgM and the numbers of T lymphocytes were determined by direct immunofluorescence. The degree of activation of the intestinal macrophages in the small intestine was assessed by measuring the β-glucuronidase (EC 3.2.1.31) released into the intestinal fluid, and also by a histochemical method. Throughout the feeding period, there were no histological alterations in the gut, but there was marked cell infiltration, mainly of plasma cells and lymphocytes. The number of macrophages on the small intestine increased significantly after feeding for 2 d, while the β-glucuronidase activity was only slightly higher that of the controls. After a 7 d feeding period, the number of IgA secreting cells increased, while the values for cells secreting IgM and IgG and for T lymphocytes remained similar to those of the controls. The effect of giving yogurt on lymphoid cells associated with the large intestine was mainly on the numbers of IgA secreting B cells and T lymphocytes, with a marked increase during the whole feeding period in the latter type of cell. Since giving yogurt mainly enhanced the IgA secreting B cells in both small and large intestines, this increase would strengthen the host's defence mechanisms in the intestinal mucosa. Although the number of macrophages was increased, there was no enhancement in their activity, which might have harmed the host by producing an inflammatory response.
Effect of polyphosphate binding on the chain dynamic of caseins: investigation by differential scanning calorimetry and thermally stimulated currents
Authors: Lamure Alain , Pommert Jean-François , Klaebe Alain , Lacabanne Colette , Perie Jean-Jacques 
Published: June 2009

SummarySamples of caseins having different Ca contents as used in cheese processing were analysed by techniques using differential scanning calorimetry and thermally stimulated currents (TSC) before and after treatment with Na poly-phosphate, a food additive used in the manufacture of processed cheese. These techniques revealed structural changes induced by the salt, and the different types of water molecules associated with the protein are evident. This characterization is in agreement with results obtained by other techniques, particularly X-ray diffraction of proteins. Transmission electron microscopy of the same samples confirmed that the changes observed by TSC were associated with an unravelling of the protein.
Isolation and partial purification of astringent compounds from ultra-high temperature sterilized milk
Authors: Harwalkar Venktesh R. , Boutin-Muma B. , Cholette H. , McKellar R. C. , Emmons D. B. , Klassen G. 
Published: June 2009

SummaryAstringent off-flavours were observed in commercial samples of UHT-milk heated by direct-steam injection. The off-flavour components from these milk samples were isolated by the chloroform-methanol extraction procedure of Harwalkar & Elliott. The astringent-tasting components in these extracts were partly purified by isoelectric precipitation at pH 7·0 and by size exclusion chromatography on Sephadex G-50 columns. The extracted off-flavour components and the partly purified samples were further analysed by FPLC using a Mono-Q anion exchange column and PAGE. The FPLC and PAGE patterns of the extracts from astringent and non-astringent samples of milk showed marked differences and the astringent flavour correlated with one of the fractions resolved by FPLC. This fraction was found to be heterogeneous by PAGE. The astringent off-flavours in UHT-sterilized milk were γ-casein-like breakdown products of casein.
The level of bitterness and solubility of hydrolysates produced by controlled proteolysis of caseins
Authors: Vegarud G. E. , Langsrud T. 
Published: June 2009

SummaryA series of hydrolysates from commercial sodium caseinate and rennet casein were prepared using different commercial proteolytic enzymes. Increasing degree of hydrolysis, DH, resulted in markedly changed solubility of the products. The level of bitterness varied with the enzyme used. Non-bitter hydrolysates of sodium caseinate were obtained with a DH of 10–12 and protein solubilities of 99%. The rennet casein hydrolysates exhibited low levels of bitterness and high solubility (90%), even at high DH values (DH = 55).
Phosphorylation of casein components by Tyrosine-specific protein kinases
Authors: Yoshikawa Masaaki , Shimada Masamitsu , Miyamura Tsuyoshi , Takeya Tatsuo , Chiba Hideo 
Published: June 2009

SummaryThe phosphorylation of different caseins by a number of tyrosine-specific kinases has been studied. The different kinases showed a range of specificities, suggesting differences in recognition mechanisms. The site of phosphorylation of αs2-casein by one phosphorylase has been identified, and compared with analogous sites in other proteins.
A 1H-NMR study of bovine casein micelles; influence of pH, temperature and calcium ions on micellar structure
Authors: Rollema Harry S. , Brinkhuis Jan A. 
Published: June 2009

SummaryThe influence of pH, temperature and Ca depletion on bovine casein micelle suspensions in D2O containing simulated milk ultrafiltrate was studied by 1H-NMR spectroscopy.In the pH range of 5·8–7·5 the spectrum of the micelles showed very little pH dependence, indicating that no changes occurred in the dynamic behaviour of the proteins constituting the micelle.The NMR spectrum of casein micelles was strongly temperature dependent, particularly in the temperature range of 60–98 °C. Increase in temperature resulted in a strong increase in spectral intensity concomitant with changes in the spectral characteristics. In micelle suspensions these changes were reversible, and indicated that at clevated temperatures the rigid structure of the casein micelle started to melt, leading to an increased mobility of appreciable parts of the proteins in the micelle.Ca depletion of the casein micelles by addition of EDTA resulted in an increase in spectral intensity, which arose from the presence of casein components in the serum phase, The spectrum of these serum phase particlcs resembled closely the spectrum of a solution of total casein in simulated milk ultrafiltrate and was quite different from the spectrum of casein micelles.The implications of these results with respect to models of the structure of bovine casein micelles are discussed.
Dissociation and reassociation of enzyme-treated caseins under high pressure
Authors: Ohmiya Kunio , Kajino Tsutomu , Shimizu Shoichi , Gekko Kunihiko 
Published: June 2009

SummaryThe effects of pressure on the association states of enzyme-treated casein molecules were studied by monitoring the turbidity of the solutions under pressures up to 3000 kg/cm2. β-Casein polymers, partly degraded with immobilized trypsin, dissociated with increasing pressure up to a critical pressure (e.g. 1200 kg/cm2) and then reassociated under the higher pressure up to 3000 kg/cm2, following a parabolic turbidity-pressure curve. In the case of chymosin-treated κ-casein, a similar pressure dependence of turbidity was found under the same pressure conditions. Based on these results, the pressure effects on dissociation and reassociation of casein molecules were discussed in terms of the volume change of water around their hydrophobic moieties.
Production of methanethiol in milk fat-coated microcapsules containingBrevibacterium linensand methionine
Authors: Kim Sun C. , Olson Norman F. 
Published: June 2009

SummaryMilk fat-coated microcapsules containingBrevibacterium linensand methionine were used to produce methanethiol, one of the volatile sulphur compounds implicated in Cheddar cheese flavour. Production of methanethiol from methionine occurred aerobically and anaerobically, but the production was 3- to 4-fold greater aerobically with most of the methanethiol being oxidized to dimethyl disulphide. About 35% of the total methanethiol was absorbed by the milk fat capsules and about 65% detected in the headspace. Levels of methanethiol began to decline at 26 °C after 24 h in milk fat-coated microcapsules. However, low temperature, such as 4–12 °C, stabilized levels of methanethiol in microcapsules over an 8-d analysis period. Optimum pH and temperature for methanethiol production were 8 and 26 °C respectively. The antioxidants butylated hydroxytoluene, butylated hydroxyanisole and ascorbic acid had negligible effects on methanethiol production.
Associations between the bovine major histocompatibility complex (BoLA) and milk production in Icelandic dairy cattle
Authors: Simpson S. Patricia , Oddgeirsson Olafur , Jonmundsson Jon V. , Oliver Robert A. 
Published: June 2009

SummaryAssociations between BoLA type and milk production were investigated using information from 80 Icelandic cattle from four dairy farms in Iceland. The specificity w6 reduced milk, fat and protein yield. Although w6 has been shown to be associated with increased susceptibility to mastitis, there is no evidence to suggest that the reduced yields here were due to mastitis. The association may be due to increased disease susceptibility or due to a direct effect of BoLA Class I antigens.
Glycoproteins in the heat- and acid-stable fraction of ovine milk
Authors: Alichanidis Efstathios , Michaelidou Alexandra-Maria 
Published: June 2009

SummaryAffinity chromatography on a concanavalin A–Sepharose support was used to isolate two glycoprotein fractions from a heat- and acid-stable fraction of ovine milk. One of these glycoprotein fractions was purified by rechromatography on DEAE-cellulose to essentially a pure protein yielding a single band on gel electro-phoresis. The apparentMrof this glycoprotein (GP2) as estimated by electrophoresis was 50500. It contained 8·88% carbohydrate and 0·61% P. The other glycoprotein fraction (GP3) contained 0·53% P and 17·76% carbohydrate including sialic acid, mannose, galactose, fucose, galactosamine and glucosamine. It appeared on electrophoresis in acrylamide gels as a slow-moving broad band. On similar treatment in the presence of sodium dodecyl sulphate it revealed four glycoprotein zones with apparentMrof 15200, 18300, 23500 and 25300. Both GP2 and GP3 contained low amounts of aromatic and sulphur-containing amino acid residues and large amounts of Asp, Glu, Ser and Leu. GP3 is similar in some respects to the bovine milk heat- and acid-stable fraction constituent, component 3.
HPLC and GLC analysis of the triglyceride composition of bovine, ovine and caprine milk fat
Authors: Barron Luis J. R. , Hierro M. Teresa G. , Santa-María Guillermo 
Published: June 2009

SummaryA total of 116 molecular species of triglycerides were identified in milk fat, using a combination of HPLC and GLC. Triglyceride composition was predicted from the random composition, which was calculated on the basis of the mole fractions of the main fatty acids making up the total triglyceride fraction. The qualitative composition of the milk fat was similar in cows', ewes' and goats' milk. In all three milks the partition number of the main triglycerides was 46, but the proportions of the triglycerides with partition numbers of 34, 38, 42, and 48 exhibited substantial differences among the milks of the three species.