bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production of a bacteriocin active on lactate-fermenting clostridia byLactococcus lactissubsp.lactisimmobilized in coated alginate beads
Authors: Zezza Nicla , Pasini Gabriella , Lombardi Angiolella , Mercenier Annick , Spettoli Paolo , Zamorani Arturo , Nuti Marco Paolo 
Published: June 2009

SummaryWe report the isolation and immobilization of a nisinogenic strain (NZ1) ofLactococcus lactissubsp.lactis, active on gas-forming lactate-fermenting clostridia responsible for late blowing of Asiago and Montasio cheeses. The bacteriocin (nisin) produced by strain NZ1 is pronase-sensitive and is released in culture media during the growth phase. Using the sensitive indicator strainLactobacillus delbrueckiisubsp.bulgaricusNCDO 1489, a rapid microtitre plate based assay was developed for quantitative determination of the bacteriocin produced by NZ1 cells, either free or immobilized in gel beads. Scanning electron microscopy of cells immobilized in calcium alginate coated beads and viable counts of the surrounding medium showed that no cell leakage occurred during a 24 h assay. The bacteriocin released from immobilized cells reached, after 5 and 24 h, concentrations comparable to that of the free cell system after 3–4 h incubation in culture media.
Evaluation of the use of an artificial teat to measure the forces applied by a milking machine teatcup liner
Authors: Adley Nicholas J. D. , Butler M. Clare 
Published: June 2009

SummaryAn artificial teat containing a force transducer was constructed to study the forces exerted by the liner on the teat during milking. The objective was to develop a method of comparing the action of different liners under a variety of different milking conditions. The rigid structure of the artificial teat did not provide an accurate representation of a real teat but deformable models used in the past have not proved practical. Initial tests of the teat showed that it gave repeatable results during calibration. When placed in a liner, however, repeatable results could not be obtained if the teat–liner interface was disturbed. The forces that were measured under simulated milking conditions varied with liner wall position and with time. There was a peak and trough prior to a stable asymptotie value being attained and a noticeable time lag behind pulsation chamber pressure. This technique can be used to compare liners when a reliable method of locating the artificial teat within the liner has been developed.
Identification ofBacillusstrains isolated from milk and cream with classical and nucleic acid hybridization methods
Authors: Tatzel Ralf , Ludwig Wolfgang , Schleifer Karl Heinz , Wallnöfer Peter R. 
Published: June 2009

SummaryA total of 529 bacterial strains have been isolated from milk and cream sampled at different sites in a dairy production plant under conditions selective for aerobic sporeforming bacteria. Identification with classical methods based on morphological, physiological and biochemical criteria showedBacillus licheniformisto be the most frequently occurringBacillussp. The investigation also revealed 62 unidentified strains. Classical identification methods were time consuming (3–7d), lacked specificity and —because of their dependence on phenotypic gene expression—sometimes produced ambiguous results. Consequently, a colony hybridization method developed for the identification ofB. licheniformisstrains and using non-radioactive labelled 23S rRNA targeted oligonucleotide probes was also used. Identification ofB. licheniformiswith borth classical and hybridization methods revealed diverging identification results for 70 strains.
A gel electrophoretic study of caprine casein
Authors: Addeo Francesco , Mauriello Rosalba , Di Luccia Aldo 
Published: June 2009

SummaryTo compare the resolving power of starch-urea gel (SUGE) and polyacrylamide-agarose gel electrophoresis (PAAGE) in caprine casein analysis, polyacrylamide gel isoelectric focusing (PAGIF) was used as reference method. The PAAGE or SUGE patterns in the first dimension were allowed to migrate by PAGIF in an orthogonal direction giving rise to two-dimensional (2-D) separations. Using this procedure, some individual bands considered to be homogeneous by SUGE or PAAGE were found to be complex mixtures of casein components. A detailed analysis of the analytical capabilities of SUGE and PAAGE was performed. Procedures based on the densitometric reading of SUGE and PAAGE patterns seemed to give inaccurate results on the quantitative composition of caprine casein. Among the electrophoretic methods assayed, the 2-D procedure gave the best resolution of casein fractions.
Influence of glycosylation on the hydration properties of caseinates
Authors: Le Meste Martine , Colas Bernard , Blond Geneviève , Simatos Denise 
Published: June 2009

SummaryGlycosylation has been recognized as enhancing some functional properties of caseinates. The present work was aimed at elucidating the structure–function relationship of the functionality of caseinates and, more particularly, the influence of hydration on these properties. Measurements of non-frozen water content derived from sorption isotherms are presented. Using spin-probing Electron Spin Resonance we studied the mobilization pattern of solutes as hydration changed.The protein interactions with bound water were not significantly affected by sugar binding. Changes in the functional properties as, for example, in the water-holding capacity, reflected alterations in the structure, which was looser and more flexible after glycosylation, and in the associative properties (increased solubility) of caseinates. Disaccharides seemed more effective than monosaccharides in inducing these changes.
Milk stability in ethanolic solutions
Authors: Pierre Alice 
Published: June 2009

SummaryWe have investigated the role of pH in the destabilization of milk and sodium caseinate solutions by ethanol. Ethanol shifted the pH of minimum stability of both caseinate and milk to higher values. A linear relation between this pH and the reciprocal dielectric constant of the mixture was observed. The addition of calcium to these alcoholic mixtures also increased the pH of minimum stability. The results are discussed in terms of the alcohol-induced shifts in the pK values of important constituent amino acids and of the effect of alcohol on soluble Ca levels.
Evaluation of a rapid fluorogenic method for the detection ofEscherichia coliin dairy products
Authors: Sarhan Hassan R. , Williams Leslie R. , Foster Howard A. 
Published: June 2009

SummaryA rapid fluorogenic medium was evaluated for the detection ofEscherichia coliin dairy products. The medium was capable of detectingEsch. coliafter 7·5 h incubation at 41·5 °C. Samples of pasteurized milk (136), raw milk (63), soft cheese (60) and pasteurized cream (39) were examined with media based on 4-methylumbelliferyl-β-D-glucuronide (MUG-7) and Violet red bile agar and there were no significant differences between the numbers ofEsch. colidetected on the two media. MUG-7 medium had a specificity of 98·6% and the small number of organisms giving a false positive reaction were identified asKlebsiella pneumoniae. The incidence of false negative results was ∼2%. MUG-7 medium was suitable for pour plate, spread plate and membrane filtration methods. Possible applications of the method are discussed.
Identification of the saturated oxo fatty acids in cheese
Authors: Brechany Elizabeth Y. , Christie William W. 
Published: June 2009

SummaryThe nature and composition of the saturated oxo fatty acids in Cheddar cheese have been re-evaluated following isolation by moern chromatographic procedures, including low-pressure column chromatography and HPLC (adsorption and silver ion modes). The oxo fatty acids were identified and quantified (for the first time) by gas chromatography–mass spectrometry in the form of the methyl ester derivatives and many of the structures were confirmed similarly by preparing picolinyl ester derivatives. Thirty-six saturated oxo fatty acids were identified, ranging in chain length from 9 to 22 with an oxo group on carbons 4–17 (except for 12), of which twenty-one had been identified in a previous study and fifteen were new. Fifteen fatty acids tentatively identified by others did not in fact appear to be present.
Assessment of mammary gland metabolism in the sow: II. Cellular metabolites in the mammary secretion and plasma during lactogenesis II
Authors: Atwood Craig S. , Toussaint Janine K. , Hartmann Peter E. 
Published: June 2009

SUMMARYThe concentrations of lactose, glucose, glucose 6-phosphate, glucose 1-phosphate, UDPglucose, UDPgalactose, UDP, UMP, inorganic phosphate, ADP and AMP (metabolites involved in the lactose synthesis pathway), and cAMP, galactose and fructose were measured in the mammary secretion from sucked (n = 9) and unsucked (n = 4) mammary glands of nine sows during the first 5 d post partum. The concentrations of lactose, glucose, galactose and fructose were also measured in plasma during this time. The progressive increase in the concentration of lactose, and changes in the concentrations of cellular metabolites in the mammary secretion from sucked glands were consistent with an increase in the metabolic activity of those glands during lactogenesis II. In contrast, unsucked glands showed a progressive decrease in the concentration of lactose, while the concentrations of cellular metabolites in the milk generally remained unchanged. These results indicated that there was no increase in the metabolic activity of unsucked glands (no increase in lactose synthesis or utilization of glucose and ATP) and that the rate of lactose synthesis prior to milk removal was limited by the availability of glucose and/or UDPgalactose. Therefore, the removal of colostrum from the mammary gland was necessary for an increase in the rate of lactose synthesis (and probably de novo fatty acid synthesis) and implies that autocrine mechanisms are operating to control the rate of milk synthesis during lactogenesis in the sow. The low concentration of glucose in colostrum compared with that in plasma is discussed in view of the paracellular pathway.
Assessment of mammary gland metabolism in the sow: III. Cellular metabolites in the mammary secretion and plasma following weaning
Authors: Atwood Craig S. , Hartmann Peter E. 
Published: June 2009

SUMMARYThe concentrations of lactose, glucose, glucose 6-phosphate, glucose 1-phosphate, UDPglucose, UDPgalactose, UDP, UMP, inorganic phosphate, ADP and AMP (metabolites involved in the lactose synthesis pathway), and cAMP, galactose and sodium were measured in the mammary secretion from four or five mammary glands on each of six sows during the first 5 d post weaning. The concentrations of lactose, glucose and galactose were also measured in plasma during this time. Following weaning, the rapid increase in the concentrations of glucose 6-phosphate and UDPgalactose suggested that the rate of lactose synthesis was regulated by the inhibition of hexokinase and/or lactose synthase, while the decrease in glucose and AMP indicated a subsequent decline in glucose and ATP utilization. The rapid increase in glucose 6-phosphate which plays a pivotal role as a substrate for both lactose and de novo fatty acid synthesis, and the rapid decrease in AMP which reflects ATP utilization, were good markers of decreased metabolic activity. These rapid changes in the metabolic activity of the mammary glands were not observed in a second weaning study when two piglets were removed from selected mammary glands for periods up to 5 h during established lactation. Since concentrations of lactogenic hormones remain elevated following partial weaning, but fall following total weaning (Rojkittikhun et al. 1991), these differences in mammary gland metabolism indicate that endocrine rather than autocrine mechanisms are controlling lactose and fat synthesis during the initial stages of total weaning.
Rheological and structural studies on heat-induced gelation of concentrated skim milk
Authors: Tobitani Atsumi , Yamamoto Haruyoshi , Shioya Toshiaki , Ross-Murphy Simon B. 
Published: June 2009

SUMMARYHeat-induced gelation of milk was studied using both rheological and structural techniques. The sample was a conventional skim milk, concentrated with an ultrafiltration membrane, which formed gels when heated at appropriate pH. We investigated some factors that are considered to affect the gelation, such as concentration, pH and rennet treatment. The gelation process was monitored with a high precision oscillatory shear rheometer and the structure of gels was evaluated with quasi-elastic laser light scattering. From these results the gelation and phase separation behaviour were determined. By combining the results for different concentrations a phase diagram was obtained, which indicated that skim milk had a two-phase region on the higher temperature side. The effects of pH and rennet treatment were also evaluated with the aid of this phase diagram. The results were discussed on the basis of concepts of the phase behaviour of polymers, which were successfully developed in polymer physics.
Acidification test based on the use of biomass for screening ofLeuconostoc. Application toLn. mesenteroidesstrains isolated from French raw milk cheeses
Authors: Demirci Yeter , Hemme Denis 
Published: June 2009

SummaryUnlike that of other lactic acid bacteria, the growth ofLeuconostocspp. in milk is poor and the resulting acidification cannot be used to distinguish different strains. An acidification test based on the use of high initial numbers (109cfu/ml) has been developed and proved to be an efficient tool for discriminating between 110Leuconostocstrains isolated from French raw milk cheeses. The pH values after 24 h ranged from 6.55 to 4.05 and distinguished four acidification groups. All 34% of the strains that acidified milk to at least pH 5.1, coagulating it and should be considered as Lac+. The differences in rates and degrees of acidification could not be related to the proteolytic activity which was, from all 27 representative strains tested, similar to that ofLactococcus lactisPrt–variants.
Seasonal influences on Cheddar cheese manufacture: influence of diet quality and stage of lactation
Authors: Kefford Bruce , Christian Mary P. , Sutherland Brian J. , Mayes Jeffery J. , Grainger Chris 
Published: June 2009

SummaryThe influence of diet quality and stage of lactation on Cheddar cheese moisture and yield were segregated and the effects of other potential variables (cow breed, milk protein genotype, age and level of mastitis) were minimized. An experiment was conducted using milk of cows in mid lactation or late lactation fed on high or low quality diets. Increased moisture in cheese was largely due to the influence of cow diet. Milk from cows given high quality diets produced lower moisture cheese. Cheese yield was influenced by diet and stage of lactation. Cows in late lactation fed on high quality diets always gave milks yielding the most cheese. Fat and protein recovery in cheese was not influenced by diet or stage of lactation. The results suggest that low quality diets may induce changes in the complex interactions of milk proteins and other components that affect cheesemaking.
A qualitative screening procedure for the detection of casein hydrolysis by bacteria, using sodium dodecyl sulphate polyacrylamide gel electrophoresis
Authors: Hill Susan H. A. , Gasson Michael J. 
Published: June 2009

SummaryIncubation of bacteria with casein at 30 °C (pH 7·2) resulted in the formation of a number of peptide fragments. The peptides were separable when subjected to electrophoresis. A proteinase-positive strain ofStreptococcus lactispreferentially hydrolysed the β-casein moiety of whole casein, and after incubation for 5 min produced a characteristic pattern of four peptides on sodium dodecyl sulphate (SDS) polyacrylamide gels. After 30 min incubation only one peptide remained. This single polypeptide was then further hydrolysed to produce one (60 min) and eventually two (120 min) lower molecular weight peptides. Hydrolysis was generally complete after about 480 min. Two proteinase-negative variants of this strain did not hydrolyse casein. Crude proteinase preparations gave the same characteristic peptide patterns. SDS-polyacrylamide gel electrophoresis was used to screen more proteinase-positive strains ofStr. Lactisfor casein hydrolysing activity. Of those so far tested all produced the same peptide patterns from β-casein. Proteinase negative variants of all these strains did not hydrolyse casein.
Cardiovascular and metabolic responses during growth hormone treatment of lactating sheep
Authors: Fleet Ivan R. , Fullerton Frances M. , Heap R. Brian , Mepham T. Ben , Gluckman Peter D. , Hart Ian C. 
Published: June 2009

SummaryPituitary-derived bovine growth hormone (bGH) was administered to six lactating Friesland ewes for 7 d. There was no consistent galactopoietic response, with changes in milk yield varying from 0 to 33% during treatment compared with the pretreatment period. The major effect of bGH on the concentration of milk constituents was to increase fat by 14·2% (P < 0·05). Treatment resulted in significant increases in arterial plasma concentrations of growth hormone, insulin-like growth factor I and glucose, with decreases in the plasma arterial concentrations of acetate and certain amino acids. There was a marked reduction in haematocrit and in haemoglobin concentration which took at least 3 d to recover. The arterio-venous difference across the mammary gland decreased for O2 during treatment and the veno-arterial difference for CO2 decreased after treatment. Mammary respiratory quotient therefore decreased significantly after bGH treatment. The results suggest that bGH exerts effects at a number of separate loci.
Plastein synthesis by the action of α-chymotrypsin on a peptic hydrolysate of whey protein
Authors: Sciancalepore Vito , Longone Vincenzo 
Published: June 2009

SummaryA peptic hydrolysate of proteinaceous material of whey from Mozzarella cheese manufacture was incubated with α-chymotrypsin under conditions leading to the formation of plastein products. The influence of incubation time, concentration and molecular size of substrate was studied. The most favourable conditions for the plastein synthesis were 12 h incubation time and 35% (w/v) concentration of peptides having mol. wt in the range 451–1450.
Effect of forage digestibility and type of concentrate on nutrient utilization by lactating dairy cattle
Authors: Gordon Frederick J. , Porter Michael G. , Mayne C. Sinclair , Unsworth Edmund F. , Kilpatrick David J. 
Published: June 2009

SummarySix lactating dairy cows were used in a three period, part balanced changeover design experiment to investigate the effects of forage digestibility and concentrate composition on the efficiency of nutrient utilization in lactating dairy cows. Six treatments comprising three forage regimens and two concentrate types (starch υ. fibre) were examined in a 3 × 2 factorial design. The three forage regimens were high digestibility grass silage offered ad lib. (HA) or restricted to 6·5 kg dry matter/d (HR) and a low digestibility grass silage offered ad lib. (LA). Within each forage regimen animals were offered 10 kg·d of supplements containing either high-starch or high-fibre concentrations. Experimental periods lasted 28 d with a 10 d recording period, during which animal performance, ration digestibility and nitrogen and energy utilization were measured. Respiratory exchange measurements were made over a 72 h period using indirect open-circuit calorimetry. Throughout the experiment, there were no significant forage × concentrate interactions in any of the intake, production or nutrient utilization results. Milk yield was significantly influenced by forage regimen (24·1, 21·7 and 21·9 kg/d for HA, HR and LA respectively) and concentrate type (21·6 and 23·5 kg/d for high-starch and high-fibre respectively). Concentrate type also significantly influenced milk protein concentration (32·8 and 30·9 g/kg for high-starch and high-fibre respectively). Forage regimen significantly influenced the efficiency of utilization of metabolizable energy (ME) for milk production (κ1) with values of 0·62, 0·64 and 0·59 for HA, HR and LA respectively. Concentrate type had no significant effect on ME intake, heat production or κ1, although animals receiving the high-fibre concentrates synthesized proportionately 0·11 more milk energy per unit of available energy (ME intake – heat production) than those receiving the high-starch concentrates. Interpolation of the values obtained with the two high digestibility forage regimens indicated that at similar ME intakes there was a trend towards a higher κ1 with the diet based on high digestibility silage, and this was in line with the higher metabolizability of the overall diet with this silage.
Isolation and quantification of cholesterol oxides in dairy products by selected ion monitoring mass spectrometry
Authors: Nielsen Jacob H. , Olsen Carl Erik , Duedahl Christina , Skibsted Leif H. 
Published: June 2009

SUMMARYA method for isolation, detection and quantification of cholesterol oxidation products based on solid phase extraction in combination with preparative HPLC and gas chromatography–mass spectrometry selected ion monitoring has been developed for dairy products. The isolation procedure had a high recovery and artifact formation was minimal, as shown by isotope labelling. The limits of detection ranged from 0.3 to 35 pg/μl of the isomeric forms of 7-hydroxycholesterol, 20α-hydroxycholesterol, the isomeric forms of cholesterol-5,6-epoxides, cholestanetriol, 25-hydroxycholesterol and 7-ketocholesterol corresponding to a limit of quantification of 2–6 ng oxysterol/g lipid in the dairy product, depending on the nature of the cholesterol oxidation product.
Temperature dependent population growth of Gyrodactylus derjavini on rainbow trout, Oncorhynchus mykiss
Authors: Andersen P. S. , Buchmann K. 
Published: June 2009

AbstractRainbow trout were experimentally infected with the ectoparasitic monogenean Gyrodactylus derjavini at three temperatures, 5.5°C, 11.6°C and 18.7°C. Subsequently, the infection level was monitored during the following 6 weeks. The population growth was positively correlated with temperature in the initial part of the investigation. At 18.7°C growth of the parasite population was fast reaching a peak abundance within 3 weeks, whereafter the infection level decreased significantly. Peak abundance was recorded in week 5 at 11.6°C. A very slow but steady parasite reproduction was noted at 5.5°C, but no peak abundance was reached within 6 weeks. The decline in parasite population after reaching peak levels is likely to be caused by a host response. The host response is also indicated by the parasites' active selection of particular microhabitats. This anti-monogenean response developed fastest at 18.7°C, more slowly at 11.6°C and was not recorded within 6 weeks at 5.5°C.