bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of caprine arthritis–encephalitis virus infection on milk cell count andN-acetyl-β–glucosaminidase activity in dairy goats
Authors: Ryan Diane P. , Greenwood Paul L. , Nicholls Paul J. 
Published: June 2009

SummaryBacteriology, somatic cell counts (SCO) andN-acetyl-β-glucosaminidase (NAGase) activity determinations were conducted on milk samples collected from does in three dairy herds with caprine arthritis–encephalitis virus (CAEV) infection. In two herds, CAEV-infected does were more likely to have a subclinical bacterial infection of the udder than CAEV-free does (P < 0·05). Does with CAEV but no bacterial udder infection had significantly greater mean SCO and NAGase activity than CAEV-free does without udder infection (P < 0·01). In two herds, changes in milk SCC and NAGase associated with CAEV infection were similar to those produced by coagulase-negative staphylococcal infections. The findings confirm that indirect indicators of bacterial mastitis infection may have reduced specificity in dairy goat herds with CAEV.
Relationships between plasmin levels in rennet caseins and proteolytic and rheological changes on storage of cheese analogues made from these caseins
Authors: Mulvihill Daniel M. , McCarthy Alice 
Published: June 2009

SummarySixteen rennet casein samples and the corresponding sixteen cheese analogues made from these caseins were obtained from a local processor. Following storage at 4°C for 6 months, pH 4·6-soluble N contents of the cheese analogues increased, while αs- and β-casein contents, elastic moduli and apparent relaxation times decreased. The β-casein and pH 4·6-soluble N contents of the 6 month old products were significantly correlated, both were significantly correlated with the plasmin (EC 3.4.21.7) contents of the corresponding rennet caseins from which the analogues were made and all three were significantly correlated with the rheological properties of the stored analogues. Of the compositional characteristics, only percent moisture in non-fat substance and percent fat in dry matter were significantly correlated (P < 0·05) with any of the proteolytic or rheological properties. The sixteen cheese analogues were also assayed at one time, when they ranged in age from 1 to 35 weeks, and highly significant interrelationships between plasmin activity, proteolysis and rheological properties were established. The results indicate that the plasmin content of rennet caseins had a significant influence on the proteolytic and rheological changes that occurred during storage of cheese analogues made from these caseins.
Secondary structures in β-casein peptide 1–42: a two dimensional nuclear magnetic resonance study
Authors: Wahlgren N. Magnus , Dejmek Petr , Drakenberg Torbjörn 
Published: June 2009

SummaryTwo dimensional NMR spectroscopy was used to study the structure of a peptide composed of the N-terminal 42 amino acid residues of β-casein. The peptide was obtained by enzymic cleavage using endoproteinase Asp-N. Complete sequence-specific 1H NMR assignment was performed for the peptide at three Ca2+ concentrations (0, 22 and 37 mM). The NMR results show that the peptide was highly flexible and adopted multiple conformations. No stable secondary structures were present; however, the peptide had some regions with non-random structure. The region between residues Leu16 and Asn27 adopted conformations with an increased contribution of α-helical structure, a so-called nascent helix. Two regions, Glu11-SerP15 and Lys29-Phe33 showed an increased population of conformations with extended structures. Addition of Ca2+ induced chemical shift changes for the backbone amide protons, especially around the phosphoserine region and around the suggested α-helical structure, indicating that the addition of Ca2+ stabilized the structure already present in the apo form of the peptide.
Responses of the bovine teat to machine milking: measurement of changes in thickness of the teat apex
Authors: Hamann Jörn , Mein Graeme A. 
Published: June 2009

SummaryChanges in the teat apex before and after different milking treatments were measured with a spring-loaded caliper device known as a cutimeter which could detect changes in thickness of the tissues of the teat end, presumably due to congestion and/or oedema, with a high degree of accuracy (± 2%) and repeatability (r = 0·99). Teat end thickness increased with increasing vacuum level. The mean increase immediately after milking with a conventional cluster was 2% for 24 teats milked at 30 kPa, 8% at 50 kPa and 21% at 70 kPa. At these vacuum levels, the mean increases for the same teats milked with an unconventional (PKME) teatcup were 10, 18 and 25% respectively. Cyclic application of 35 kPa positive pressure to the pulsation chamber of a conventional teatcup operating at 50 kPa reduced teat end thickness by 8% compared with the mean premilking value. Although most teats returned to within ± 2% of their premilking thickness values by 1 h after milking, differences were apparent between different milking systems for up to 4 h postmilking.
A reference milk system for instrumental measurement of milk fat and protein
Authors: Clarke Timothy 
Published: June 2009

SummaryA reference milk system (Clarke system) using primary reference milks made from preserved natural bovine milks (PNM) and standard reconstituted milk (SRM) has been developed to enable accurate calibration of milk analysing instruments. The PNM have values of 2, 3, 4, 5 and 6% fat and 3·5, 2·7, 3·4, 4·2 and 3·3% protein respectively and can be stored for 4 months without detectable change in fat or protein content. The above reference milk system utilizes SRM as a secondary reference milk to enable regular checking of the stability of the instrument calibration during routine testing (e.g. after every 100 samples). Over several months seven laboratories using 13 fat-testing instruments and seven protein-testing instruments achieved high levels of accuracy in weekly calibrations (coefficient of variation 1·1%) when they used the reference milk system and adhered to the prescribed calibration criteria.
Composition and structure of micellar calcium phosphate
Authors: Holt Carl , van Kemenade Mathea J. J. M. , Nelson Lowell S. , Sawyer Lindsay , Harries John E. , Bailey Raymond T. , Hukins David W. L. 
Published: June 2009

SummaryMicellar calcium phosphate has the chemical composition and physicochemical properties that are consistent with it being a complex of the phosphate centres of casein with an acidic amorphous calcium phosphate. Similar acidic amorphous calcium phosphates have been prepared in the laboratory and for these, as well as for micellar calcium phosphate, the most appropriate crystalline model compound from which the short-range structure may be derived is brushite, CaHPO4.2H2O. The predicted secondary structures around sites of phosphorylation in the Ca2+-sensitive caseins often comprise an α-hclix-loop-α-helix motif with the sites of phosphorylation in the loop region. This motif may be important in linking the colloidal calcium phosphate with casein in native casein micelles.
Monitoring of B-complex vitamins in yogurt during fermentation
Authors: Kneifel Wolfgang , Holub Sonja , Wirthmann Maria 
Published: June 2009

SummaryEight commercially available yogurt starter cultures were examined for their ability to synthesize water-soluble vitamins. In order to yield comparable assaying conditions, 12·5% reconstituted whole milk was used for yogurt production throughout the experiments. When applying the traditional method of yogurt manufacture (short-time incubating at 42 °C/3–4 h) with all cultures the following vitamins were enriched during fermentation by more than 20%: thiamin (two cultures), pyridoxine (four cultures), folic acid (one culture), and biotin (two cultures). Two starter cultures were selected and used to compare vitamin profiles during the two different methods of fermentation. In contrast to short-time incubation, long-time yogurt production (30 °C/14–16 h) led to a lesser production of folic acid, but to increased concentrations of thiamin and of nicotinic acid.
Feeding calcium soaps of fatty acids to lactating cows: effect on production, body condition and blood lipids
Authors: Sklan David , Bogin Eytan , Avidar Yaakov , Gur-Arie Shai 
Published: June 2009

SummaryCa soaps of fatty acids (CSFA, 0·5 kg/d) were added to the diet of lactating cows for 170 d, and production, body condition score and blood lipids were examined.Production of fat-corrected milk was increased by 1·5 kg/d owing to increase in both milk and fat production. Over 250 d lactation, production of fat-corrected milk was enhanced by 1·3 kg/d. Body condition scores were lower in cows fed CSFA in early lactation, but tended to exceed those of control cows after 80 d lactation. Reproductive performance was improved in cows fed CSFA.Serum total lipids, phospholipids and cholesterol were increased in CSFA cows at 15 and 29 d but not at 59 d post partum. The cholesterol increase was mainly in the high density lipoprotein fraction.
Cheddar cheesemaking from whole milk concentrated by ultrafiltration and heated to 90 °C
Authors: Green Margaret L. 
Published: June 2009

SummaryCheddar cheeses were made from milks concentrated approximately 2·3-and 3·4-fold by ultrafiltration, then heated at 90 °C for 15 s. They were compared with cheeses made from pasteurized unconcentrated milks and unheated 5·3-fold concentrates. The recoveries of fat and protein were comparable in the cheeses from heated 2·3-fold concentrates and unheated 5·3-fold concentrates and both were higher than the controls. However, fat losses were high in curds from 3·4-fold heated concentrates. The use of paired fast and slow starter strains and coagulation at 26 °C optimized the curd composition. Proteolysis and flavour development were only slightly reduced in all the cheeses from concentrated milks, perhaps aided by higher starter levels in the curd than in the controls. The structures of the curds from the heated concentrated milks were coarser than those of the controls and the curd particles fused poorly. This may explain the grainy, dry, crumbly texture in the cheeses from the heated concentrates. The texture was not improved by adding a bacterial proteinase to the curd.
Effects of cations and anions on the rate of the acidic coagulation of casein micelles: the possible roles of different forces
Authors: Bringe Neal A. , Kinsella John E. 
Published: June 2009

SummaryRaw skim milk was diluted 1000-fold using distilled water or various salt solutions as specified. Smooth, hyperbolic profiles of coagulation ratev.pH for casein were calculated from recordings of turbidity (400 nm) with time. The effects of pH, cation type, anion type and cleavage ofk−casein by chymosin (EC 3.4.23.4) were determined. The maximum of pH-coagulation rate profiles decreased by 63, 85 and 94% when the skim milk diluent was changed from water to salt solutions of NaCl (100 mM), CaCl2(50 mM) or MgCl2(50 mM). The maximum of the pH–coagulation rate profile was 15 times greater when the Ca salt was changed from CaCl2to Ca(SCN)2(50 mM). The highest pH at which casein coagulation occurred increased from 4·45 to > 6·0 when Cu2+(1 mM) was included with casein micelles dispersed in CaCl2solution (50 mM). The addition of chymosin to casein micelles suspended in CaCl2solution (70 mM) eliminated the inhibition of casein coagulation by Ca2+at pH 4·5. It is proposed that ions such as Mg2+, Ca2+, and Na+, which generally associate with casein phosphate and carboxylate groups, increased the H+concentration required to initiate the coagulation of casein, because H+must displace bound Ca2+, Mg2+or Na+to reduce repulsive hydration forces between casein micelles, allowing attractive hydration forces (e.g. hydrophobic phenomena) to cause casein coagulation. Furthermore, it is proposed that ions such as Cl−, Br−,and SCN−bind to lysine, arginine and histidine groups and thereby decrease repulsive hydration forces between cationic casein micelles.
Microbial study of Casar de Cáceres cheese throughout ripening
Authors: Poullet Blanca , Huertas Manuel , Sánchez Antonio , Cáceres Pilar , Larriba German 
Published: June 2009

SummarySix batches of Casar de Cáceres raw ewes' milk cheeses were examined throughout their ripening. Three were made in winter, the others in spring. The microbial counts in the interior of the cheeses were ∼1·5 log units higher in the winter cheeses for total viable counts, lactic streptococci and leuconostocs, and >2 log units higher for total enterobacteria, coliforms and faecal coliforms in the 60 d samples. Staphylococci were not detected after day 15 of maturation in spring cheeses, but reached 1 log unit at day 60 in the interior of winter cheeses. In the surface samples, differences in microbial counts were more marked. Values of some physicochemical indices, such as pH, % moisture content and % NaCl were also determined.
Influence of milk flow rate on new intramammary infection in dairy cows
Authors: Grindal Robert J. , Hillerton J. Eric 
Published: June 2009

SummaryIn a series of short-term experiments cows were subjected to exaggerated bacterial challenge and accentuated milking machine conditions known to predispose to new mammary infection. The incidence of new intramammary infection was significantly greater in quarters with peak flow rates > 1·6 kg/min whether they were exposed to impacts (P< 0·05) or milking without pulsation (P<0·001). The infection rates were much lower (P< 0·001) in quarters milked with ‘pulsation and shields’ to protect against these two machine factors. Despite this, quarters with peak flow > 1·6 kg/min still showed a 12-fold increase in mastitis incidence compared with quarters with peak flow < 0·8 kg/min. Rates of milk flow have increased dramatically in the last 40 years through selection and breeding: whole udder peak flow rates in heifers have doubled from 1·9 to 3·8 kg/min. Increased emphasis, therefore, should be placed on hygiene, husbandry and milking techniques to minimize bacterial numbers at teat ends to control mastitis as the drive for higher flow rate and yield make cows increasingly more susceptible to infection. These results suggest that the benefits of reduced infection rate from mastitis control are significantly underestimated since animals are now considerably more susceptible than 40 years ago.
Proteolytic activity of two commercial proteinases from Aspergillus oryzae and Bacillus subtilis on ovine and bovine caseins
Authors: López-Fandiño Rosina , Ramos Mercedes , Fernández-García Estrella , Olano Agustin 
Published: June 2009

SummaryElectrophoretic analysis of the action of two commercial enzymes, Neutrase 0·5 and MKC Fungal Protease, on whole casein and αs-, β- and κ-caseins from cows' and ewes' milk showed that Neutrase 0·5 chiefly degraded β-casein, giving rise to peptides soluble at pH 4·6 detectable by PAGE. In contrast, although MKC Fungal Protease caused intense hydrolysis of bovine β-casein, in ovine casein it resulted in more active degradation of αs- than β-casein. The latter enzyme did not produce peptides soluble at pH 4·6 detectable by PAGE. Both enzymes degraded κ-casein, yielding a breakdown product that exhibited an electrophoretic mobility similar to that of the breakdown product produced by the action of commercial rennet.
A new fermented milk using capsular polysaccharide-producing Lactobacillus kefiranofaciens isolated from kefir grains
Authors: Toba Takahiro , Uemura Hitoshi , Mukai Takao , Fujii Toshihiro , Itoh Takatoshi , Adachi Susumu 
Published: June 2009

SummaryA new fermented milk was prepared by using capsular polysaccharide-producing Lactobacillus kefiranofaciens K1 isolated from kefir grains. Fermentation was carried out at 30°C for 18 h, when pH 4·5 was attained. The product had a ropy consistency and was resistant to syneresis. However, the product was given lower scores for acceptability by a consumer panel than a similar product made with Lb. delbrueckii subsp. bulgaricus.
Trials of a novel mastitis sensor on experimentally infected cows
Authors: Lake John R. , Hillerton J. Eric , Ambler Barry , Wheeler Helen C. 
Published: June 2009

SummaryNumerous attempts to develop in-line Systems for the measurement of the electrical conductivity of milk as an aid to the detection of mastitis have been described. The major technical problem of fouling of electrodes exposed to milk has been overcome in the sensor tested here by use of an inductive System of measurement. The practical application of this System in the milking parlour is reported. The novel mastitis sensor has been shown to detect incipient mastitis before there are visible signs of abnormal milk. Conductivity measurements have the advantage over other diagnostic procedures in that the information is available immediately without additional effort. Normalized conductivity and milk yield variation results indicate the potential for developing a practical, automatic System for mastitis detection.
Efficiency of cleaning agents for an inorganic membrane after milk ultrafiltration
Authors: Daufin Georges , Merin Uzi , Kerherve François-Louis , Labbe Jean-Pierre , Quemerais Auguste , Bousser Charles 
Published: June 2009

SummaryCleaning of inorganic membranes after ultrafiltration (UF) of skim milk has been assessed using hydraulic, physicochemical and spectroscopic (i.r. and X-ray photoelectron spectroscopy) measurements. A cleaning sequence using hypochlorite alone or hypochlorite followed by HNO3 restored the membrane hydraulic resistance, in contrast to cleaning with HNO3 alone. When using NaOH, addition of Ca complexants (EDTA, gluconate, tripolyphosphate) and surfactants was required to obtain similar results. Three types of criteria (hydraulic, kinetic, chemical) are available to assess the effect of the sequestrant and surfactant types. In all the cases studied, traces of protein and Ca were detected on and within the membrane after cleaning. Nevertheless, it was concluded that it is possible to develop a single-step alkaline product to clean inorganic milk UF membranes if suitable surfactants and Ca sequestrants are included in its formula.
Isolation and characterization of α2-macroglobulin from mastitis milk
Authors: Rantamäki Liisa K. , Müller Hans-Peter 
Published: June 2009

SummaryWhey samples were screened for the presence of the proteinase inhibitor α2-macroglobulin (α2M). From an enzymic test, α2M levels in normal whey varied in the range 0·49–0·84% of the serum level, whereas in mastitis whey the activity was markedly increased, reaching values between 0·91 and 138·5% (median 7·2%) of standard serum level. In mastitis milk samples but not in normal milk α2M was also detected by double immunodiffusion and Western blotting. The proteinase inhibitor was purified from a mastitis milk sample with high α2M activity (138·5% of serum level). In SDS-PAGE, native-PAGE and in double immunodiffusion analysis the inhibitor appeared indistinguishable from plasma-derived α2M. The α2M preparation from mastitis whey migrated essentially as native α2M, representing the ‘slow’ form of the molecule. Treatment with trypsin transformed the α2M preparation to the electrophoretic ‘fast’ form, but treatment with methylamine had only a minor effect. The receptor recognition sites were not exposed on the isolated α2M molecule but could be readily exposed by treatment of the proteinase inhibitor with trypsin, which further proved that the isolated α2M was in the entire native, functionally active state.
Characterization of the oligopeptides of Parmigiano-Reggiano cheese soluble in 120 g trichloroacetic acid/1
Authors: Addeo Francesco , Chianese Lina , Sacchi Raffaele , Musso Salvatore Spagna , Ferranti Pasquale , Malorni Antonio 
Published: June 2009

SummaryThe non-protein nitrogen (NPN) of samples of Parmigiano-Reggiano cheese ripened for 6 and 15 months was fractionated by ion-exchange chromatography on a Cu2+-Chelex column to separate oligopeptides from free amino acids. Peptide components were isolated by reversed-phase HPLC and identified by fast atom bombardment–mass spectrometry (FAB–MS). Only the NPN fraction of 6 month old cheese samples contained enough peptides to be further characterized. On the basis of FAB–MS spectral results, 39 oligopeptides were identified, the main components being phosphopeptides. Two sets of both intact and partly dephosphorylated peptides, accounting for a total of 19 phosphopeptides, were formed by the hydrolysis of β–casein and belonged to regions 1–20 and 6–28 of β–casein. The formation and potential role of these peptides in cheese is discussed.
Development of bacterial biofilms in dairy processing lines
Authors: Austin John W. , Bergeron Gilles 
Published: June 2009

SummaryAdherence of bacteria to various milk contact sites was examined by scanning electron microscopy and transmission electron microscopy. New gaskets, endcaps, vacuum breaker plugs and pipeline inserts were installed in different areas in lines carrying either raw or pasteurized milk, and a routine schedule of cleaning-in-place and sanitizing was followed. Removed cleaned and sanitized gaskets were processed for scanning or transmission electron microscopy. Adherent bacteria were observed on the sides of gaskets removed from both pasteurized and raw milk lines. Some areas of Buna-n gaskets were colonized with a confluent layer of bacterial cells surrounded by an extensive amorphous matrix, while other areas of Buna-n gaskets showed a diffuse adherence over large areas of the surface. Most of the bacteria attached to polytetrafluoroethylene (PTFE or Teflon™) gaskets were found in crevices created by insertion of the gasket into the pipeline. Examination of stainless steel endcaps, pipeline inserts, and PTFE vacuum breaker plugs did not reveal the presence of adherent bacteria. The results of this study indicate that biofilms developed on the sides of gaskets in spite of cleaning-in-place procedures. These biofilms may be a source of post-pasteurization contamination.
Calmodulin-binding peptides isolated from α-casein peptone
Authors: Kizavva Kenji , Naganuma Keiko , Murakami Umeji 
Published: June 2009

SUMMARYPeptides that inhibit calmodulin-dependent cyclic nucleotide phosphodiesterase were isolated from a pepsin digest of α-casein. Analysis of these peptides showed that they corresponded to the αs2-casein sequences 164–179 (Leu–Lys–Lys–Ile–Ser–Gln–Arg–Tyr–Gln–Lys–Phe–Ala–Leu–Pro–Gln–Tyr), 183–206 (Val–Tyr–Gln–His–Gln–Lys–Ala–Met–Lys–Pro–Trp–Ile–Gln–Pro–Lys–Thr–Lys–Val–Ile–Pro–Tyr–Val–Arg–Tyr) and 183–207 (C-terminus, Val–Tyr–Gln–His–Gln–Lys–Ala–Met–Lys–Pro–Trp–Ile–Gln–Pro–Lys–Thr–Lys–Val–Ile–Pro–Tyr–Val–Arg–Tyr–Leu). These peptides inhibited calmodulin-induced cyclic nucleotide phosphodiesterase activity over the range 1–50 μM without affecting the basal enzyme activity. These results demonstrated that the affinities of these peptides for calmodulin are comparable to the affinities of certain endogenous neurohormones and proteins that interact with calmodulin.