bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymic dephosphorylation of bovine casein to improve acid clotting properties and digestibility for infant formula
Authors: Li-Chan Eunice , Nakai Shuryo 
Published: June 2009

SummaryTo improve acid clotting properties, enzymic dephosphorylation of caseins with calf intestinal alkaline phosphatase (CAP) or potato acid phosphatase (PAP) was investigated. Greater dephosphorylation was achieved using αs1- or β-casein as substrates, compared to whole casein or skim milk. Electrophoresis of PAP-modified caseins revealed bands with lower mobility and a multibanded pattern in the β-casein region which was similar to that of human β-casein. On the other hand, CAP modification produced electrophoretic bands having lower mobility of the β-casein component, but with higher mobility in the αs1-casein component as well as increased net negative charge in the CAP-casein. PAP-casein formed a fine dispersion upon acidification to pH 4. with a microstructure similar to that of acidified human casein. Greater initial rates of hydrolysis by pepsin at pH 4 were observed for both CAP- and PAP-modified caseins, compared to bovine and human caseins. The rate and extent of hydrolysis remained high for CAP-casein but tended to level off with PAP-casein during sequential digestion with pepsin and pancreatin. There may be advantages in the use of partial dephosphorylation to improve acid clotting and digestibility properties of bovine casein for infant feeding.
The structure of casein micelles between pH 5·5 and 6·7 as determined by light-scattering, electron microscopy and voluminosity experiments
Authors: Vreeman Henk J. , van Markwijk Bas W. , Both Paula 
Published: June 2009

SummaryHydrodynamic radii from inelastic light-scattering experiments and radii of gyration from Zimm plots give an indication of the change of average casein micelle size when the pH is changed. Combination of the results of both types of measurements gives information on changes in the micelle protein matrix, i.e. changes in the voluminosity.The voluminosity was also determined by the pellet method and by electron microscopy which also provided comparative data on size parameters.
Experiments on the heat-induced salt balance changes in cow's milk
Authors: Pouliot Yves , Boulet Marcel , Paquin Paul 
Published: June 2009

SummaryThe heat-induced changes in sait balance between the colloidal phase of milk and its serum were studied using an ultrafiltration technique. Milk permeate was isolated at the heating temperature by means of a hollow fibre ultrafiltration cartridge coupled with a stainless steel heat exchanger unit. The milk samples initially at 4 °C were heated to 20, 40, 60, 80 or 90 °C. Ca, P, Mg and citrate contents of the permeates were determined. The decreases in Ca and P were proportional to the increase in temperature. Smaller losses in Mg and citrate were observed. An initial sharp decrease in concentration occurred within the first seconds of holding time and was followed by a slower and smaller decrease. The possible occurrence of a two-stage mechanism for the heat-induced salt precipitation is discussed. The precipitation of dicalcium phosphate is believed to occur together with some tricalcium citrate precipitation.
Lipase redistribution in cows' milk during induced lipolysis II. Activation by milk pH adjustment
Authors: Cartier Philippe , Chilliard Yves , Bout Josiane 
Published: June 2009

SummaryCold-stored milk lipolysis was enhanced from 5- to 50-fold when milk pH was adjusted to 7–8 with NaOH, while it was greatly decreased or stopped by an adjustment to pH 6–5·5 with citric acid. Small adjustments in pH (≤ 0·5 pH unit) also affected lipolysis, but the pH of native milk was not related to spontaneous lipolysis. The binding of lipoprotein lipase to cream was a pH-dependent process with an optimum near pH 7·0. Activity of the cream lipase on cold-stored milk fat continuously increased from pH 6·6 to pH 8·5. The activating effect of heparin on cold-stored milk lipolysis reached a maximum at pH 7·0–8·0 and a minimum in native milk, while addition of blood serum gave an opposite response.
Changes in milk plasminogen, plasmin andin vitrobacterial growth in whey during early lactation
Authors: Kaartinen Liisa , Pyörälä Satu 
Published: June 2009

SummaryThe activity of milk plasmin, plasminogen andN-acetyl-β-glucosaminidase (NAGase) and the trypsin-inhibitor capacity (TIC) were monitored in 40 quarters during the first month of lactation. TIC and NAGase activity decreased rapidly and plasmili activity more slowly during the first week. Conversely milk plasminogen increased as time elapsed from parturition. When the quality of whey was analysed as a growth medium for mastitis pathogens, a slight inhibition in the growth ofEscherichia coli, Staphylococcus aureusandStreptococcus agalactiaewas seen at the day of parturition. There was a distinct stimulatory effect on the growth ofStr. agalactiaeduring the second week of lactation. No relationship was found betweenin vitrobacterial growth and respective plasmin or plasminogen activity in milk.
Sandwich enzyme immunoassay ofMucor mieheiproteinase (Fromase) in cheese
Authors: Rauch Pavel , Hochel Igor , Beránková Eva , Káš Jan 
Published: June 2009

SummarySandwich enzyme immunoassay ofMucor mieheiproteinase (from the commercial preparation Fromase) has been developed using horseradish peroxidase as a marker. The enzyme may be determined to a detection limit of 50 ng/ml. Slight cross reactions by chymosin, bovine, porcine and chicken pepsin did not affect the assay. Recovery of Fromase added to cheese extracts varied between 92 and 106%. The method was used for the determination ofM. mieheiproteinase in different cheese extracts.
The effects of intraruminal infusions of urea on the voluntary intake and milk production of cows receiving grass silage diets
Authors: Choung Jai-Jun , Chamberlain David G. , Thomas Phillip C. , Bradbury Ian 
Published: June 2009

SummaryResponses of dairy cows given silage diets to the intraruminal infusion of urea in progressively increasing doses were studied in four experiments, two with non-lactating cows and two with lactating cows. No clinical symptoms of NH3 toxicity were observed in any of the experiments. When urea was infused continuously, silage intake was depressed (P < 0·05) when the total supply of N exceeded the equivalent of 250g crude protein (CP)/kg DM in the total diet. However, when the urea load was administered twice daily, as opposed to continuously, intake depression (P < 0·05) occurred at the equivalent of 170g CP/kg DM. At the higher doses of urea, concentrations of NH3 in peripheral blood increased and were accompanied by increased concentrations of glucose and reduced levels of insulin in plasma. In general, responses of milk production followed those of silage intake but there was evidence of greater proportional reductions in the yield of lactose relative to that of fat and protein. It is concluded that the voluntary intake of high-protein silages may be depressed by factors associated with high rates of absorption of NH3 from the rumen.
Effect of coagulation and washing conditions on fines, water holding capacity and microstructure of acid casein curd
Authors: Fichtali Jaouad , van de Voort Frederik R. , Toupin Christian J. 
Published: June 2009

SummaryAcid casein was prepared under various conditions of pH, concentration and wash regimens (temperature, time, agitation and wash water ratio) according to a response surface experimental design. The resulting product was analysed for water-holding capacity and loss of fines, and the structure of the curd assessed by scanning electron microscopy. Concentration, pH and temperature were the major factors in terms of influencing fines, water-holding capacity and the microstructure of the curd. Fines could be minimized by selecting appropriate pH, concentration and agitation conditions. The final moisture content of the curd was mainly controlled by pH, concentration and temperature and may aid in the selection of parameters to obtain good dewatcring and drying efficiencies. Microstructural analysis visualized the effects of pH, concentration, temperature and their interactions on the casein structural network and the effects of the process parameters are discussed in relation to those changes. Response surface methodology was shown to be an effective tool for examining which variables used in the process were significant and provided guidance as to the type of physicochemical mechanisms affecting the system.
New equation for prediction of water activity in unripe cheese
Authors: López Pascual , Marcos Andrés , Esteban María A. 
Published: June 2009

SummaryThe water activity of fresh cheese made from cows', ewes' and goats' milk, as well as curd cheese and whey cheese, responds to the equation aw = 0·9719−0·0044[NaCl] + 0·0041 pH, with a square of multiple correlation coefficient R2 = 0·95. This equation was obtained by multiple regression analysis of data point sets of the variables x (g NaCl/100 g moisture), y (pH) and z (water activity, aw) determined as the average of values provided by six samples of each unripe product. Application of this equation to 30 individual samples of unripe dairy products investigated yielded calculated aw values within ±0·005 and ±0·002 aw units of the experimental water activities in 86·7% and 53·3% of the samples, respectively. These results are closer to the experimental values than those provided by earlier predictive equations.
Lactational changes in oxytocin release, intramammary pressure and milking characteristics in dairy cows
Authors: Mayer Harald , Bruckmaier Rupert , Schams Dieter 
Published: June 2009

SummaryTwo experiments were conducted to investigate possible changes of milking-related oxytocin release (Expt 1) and of intramammary pressure and milking characteristics (Expt 2) throughout entire lactations in German Braunvieh dairy cows. Mean oxytocin concentrations after stimulation at onset of milking increased from 18·3 ± 15·9 to 30·7 ± 24·1 pg/ml in Expt 1 and decreased from 23·9 ± 17·6 to 15·4 ± 9·1 pg/ml in Expt 2, respectively, but remained above the level necessary to elicit complete milk ejection in both trials. Premilking baseline intramammary pressure had its maximum in early lactation until about month 4 and then decreased to ∼50% of its initial level. Ejection pressure followed a similar pattern, but dropped only to ∼75% of its maximum. This was due to the constant elevation of pressure increase, reaching its highest level in late lactation. Time from commencement of stimulation until maximum pressure exceeded 1 min in almost all instances even in early lactation and increased throughout lactation. Despite the normal decrease of milk yield average milk flow fell only slightly while maximum flow rate remained almost constant. Pressure increase, milk yield and milk flow were not different after 1 min and after extended stimulation. Thus there were no indications of a decreasing sensitivity of the milk ejection reflex during lactation, and milking characteristics were positively affected by intense teat stimulation. Suggestions for practical dairying are made.
Changes in concentrations of insulin-like growth factor 1, insulin and growth hormone in bovine mammary gland secretion ante and post partum
Authors: Einspanier Ralf , Schams Dieter 
Published: June 2009

SummaryConcentrations of insulin-like growth factor 1 (IGF-1), insulin and growth hormone were measured in the secretion of the bovine mammary gland from day 70 ante partum until 6 d post partum. Highest levels were found during the last 2 weeks ante partum followed by a rapid decrease during the first milkings post partum. The association of IGF-1 with its binding proteins in milk was analysed and striking differences were found in the distribution of bound and free IGF-1. IGF-1 appeared mainly in the bound form (91%) at days 40–2 ante partum. Free IGF-1 preponderated in the first milkings post partum (73%) and changed again to about 85% in the bound form after day 4 post partum. A slightly acidic pH (6·3) of the secretion was correlated with high amounts of free IGF-1. Gel filtration experiments revealed a possible pH-dependent mechanism for the binding of IGF-1 to its binding proteins in milk.
Effect of temperature on the moisture sorption isotherms of a heat-treated whole milk product, khoa
Authors: Sawhney Ish K. , Patil Girdhari R. , Kumar Bikram 
Published: June 2009

SummaryMoisture sorption isotherms of khoa were determined at 15, 25, 35 and 45 °C over a water activity (aw) range of O·l 1–0·97. The isotherms were sigmoid (Type II) and were fitted to the Guggenheim–Anderson–de Boer (GAB) equation (Bizot, 1983). The aw of freshly made khoa was found to be 0·96. The aw of khoa increased with increasing temperature up to 0·9; above this the effect of temperature on aw diminished. The monolayer moisture content of khoa decreased with increasing temperature. The equations describing the temperature dependence of GAB constants were determined in the form of the Clausius–Clapeyron equation. The net isosteric heat of desorption of khoa decreased rapidly until a moisture level of 0·1 g/g solids, and approached a constant value of 0·43 kJ/mol above a moisture level of 0·25 g/g solids.
Preparation of whey protein concentrate from salted whey and its use in yogurt
Authors: El-Salam Mohamed H. Abd , El-Shibiny Safinaz , Mahfouz Mohamed B. , El-Dein Hala F. , El-Atriby Hossein M. , Antila Veijo 
Published: June 2009

SummarySalted whey (7–8% NaCl) was concentrated by ultrafiltration by a factor of 20. Sweet whey equal to the retentate volume was added and ultrafiltration was continued to a concentration factor of 20. Addition of sweet whey and ultrafiltration was repeated twice more for almost complete removal of salt from whey protein concentrate (WPC). The protein content of WPC was adjusted to 3·5% using sweet whey and the mixture was heated to 65°C for 30 min. This was mixed with buffalo milk at the rate of 0, 10, 20 or 30% and then heated at 80°C for 1, 5 or 20 min before use for yogurt manufacture. The chemical, rheological and organoleptic properties of the yogurt were investigated. WPC could be added to buffalo milk at up to 20% without affecting the quality of the yogurt produced. On the contrary, it improved the texture, mouthfeel and wheying-off of yogurt from buffalo milk. Yogurt with 30% WPC had an unacceptably weak body and texture for a set product. Heating at 80°C for 5 min was sufficient to produce good quality yogurt from buffalo milk containing WPC.
Effect of inclusion of saliva salts in the diet on milk yield and composition in dairy cows
Authors: Hadjipanayiotou Miltos , Rowlinson Peter , Harrison David G. , Armstrong David G. 
Published: June 2009

SummaryTwenty multiparous Jersey cows, paired according to previous lactation yield and expected date of calving, were given two diets in a cross-over experiment in early lactation. The diets had forage:concentrate ratios maintained at 3:7, the forage being wilted grass silage and the concentrate either a proprietary dairy cake or the same cake containing saliva salts (SS) at 40 g/kg dry matter. The SS diet proved acceptable to the animals and had no effect on gestation length or calf survival. Absolute milk yields were not affected, but the SS diet caused a significant increase in the proportions of milk fat, total solids (both P < 0·001) and protein (P < 0·05) and in the yield of fat-corrected milk (P < 0·001). Analysis of rumen liquor samples showed that giving the SS diet resulted in a significant increase in the molar proportion of acetate and a decrease in the proportions of propionate and to a lesser extent butyrate. Milk fat content showed significant correlations with ruminal acetate (r = 0·67), propionate (r = −0·59) and the acetate: propionate ratio (r = 0·64).
Antibacterial and antiviral activity of camel milk protective proteins
Authors: El Agamy El Sayed I. , Ruppanner Roger , Ismail Amin , Champagne Claude P. , Assaf Robert 
Published: June 2009

SummaryLysozyme (LZ), lactoferrin (LF), lactoperoxidase (LP), immunoglobulin G and secretory immunoglobulin A were extracted from camel milk. The activity of these protective proteins was assayed againstLactococcus lactissubsp.cremoris, Escherichia coli, Staphylococcus aureus, Salmonella typhimuriumand rotavirus. Comparative activities of egg white LZ, bovine LZ and bovine LF are also presented. The antibacterial activity spectrum of camel milk LZ was similar to that of egg white LZ, and differed from bovine milk LZ. Bovine and camel milk LF antibacterial activity spectra were similar. The camel milk LP was bacteriostatic against the Gram-positive strains and was bactericidal against Gram-negative cultures. The immunoglobulins had little effect against the bacteria but high titres of antibodies against rotavirus were found in camel milk. The LP system was ineffective against rotavirus.
Collection of fore and hind milk from the sow and the changes in milk composition during suckling
Authors: Atwood Craig S. , Hartmann Peter E. 
Published: June 2009

SummaryA new sampling method for the collection of fore and hind milk from the sow has been developed which resembles normal milk removal by the piglet, yet overcomes the difficulties of collecting milk that is available for only a short time (10–20 s) at each let-down. Samples of hind milk were collected immediately after the completion of a successful sucking, while the fore milk was collected at the beginning of the next natural let-down. Modification of existing assays for fat, protein and lactose was required to provide rapid analysis of the small volumes (< 0·5 ml) of milk collected using this procedure, and these methods were validated by comparison with reference methods. Total solids and the concentration of fat in whole milk, and protein and lactose in skim milk, were measured in fore and hind milk collected from 4, 20, 12 and 12 sows respectively, 6–11 d post partum. For fore milk, the results (mean ± SD (n)) were: total solids, 199·9±9·9 g/1 (8); fat, 96·7 ± 13·9 g/1 (41), protein, 47·7±4·5 g/1 (27) and lactose, 58·3 + 4±0 g/1 (27). In hind milk, there was a significant increase in the concentration of fat (15·3 g/1, p < 0·001, n = 41) which was reflected by a significant increase in total solids (14·7 g/1, P < 0·001, n = 8) and calculated energy (511 kj/l, P < 0·001, n = 27), but there was no significant difference in the concentration of either protein or lactose. This increase in milk fat during milk letdown is in contrast to the results of most previous studies in the sow and is discussed in terms of the possible mechanisms that may cause the concentration of fat to increase as milk is removed from the mammary gland.
Accelerated cheese ripening: use of Lac−mutants of lactococci
Authors: Birkeland Stein-Erik , Abrahamsen Roger K. , Langsrud Thor 
Published: June 2009

SummaryLactose-negative mutants ofLactococcus lactissubsp.lactisandLacto-coccus lactissubsp.cremoriswith good autolytic properties were used at two different levels in addition to the normal starter in Gouda-type cheesemaking experiments. Increased numbers of bacteria were observed in fresh cheese, and the pH changes during ripening were as normal. A more rapid development of soluble N compounds was observed in cheeses with mutant addition, especially withLc. lactissubsp.lactisIMN-L2–3 andLc.lactissubsp.cremorisIMN-C12–1, compared with the control cheese. Cheese with addedLc. lactissubsp.lactisIMN-L2–3 andLc.lactissubsp.cremorisIMN-C12–1 showed the most extensive ripening and the highest product quality of the mutants tested. The experimental cheeses were graded higher than the control cheese. The ripening time was significantly reduced, and the quality was retained at an acceptable level during storage.
Intramammary pressure and luteal oxytocin after PGF2α administration in cycling and early pregnant ewes
Authors: Marnet Pierre-Guy , Labussière Jacques 
Published: June 2009

SummaryThe aim of this work was to investigate whether luteal oxytocin released after non-luteolytic prostaglandin F2α (PGF2α) challenge could explain the intramammary pressure (IMP) rises previously described in pregnant ewes after the normal life span of a corpus luteum. Blood oxytocin levels and IMP after challenge were measured in cycling and pregnant lactating ewes until the response ceased (˜ 55 d post oestrus). Oxytocin release was not significantly different for cycling and pregnant ewes, and fell to its lowest levels on days 16–18 post oestrus in both groups, i.e. with or without luteolysis. However, although IMP response fell with luteolysis in cycling ewes, the response persisted until day 55 in pregnant ewes. This lack of correlation between oxytocin release and IMP response raised interesting questions including: is there an unknown oxytocic compound that can be released after PGF2α stimulation of the corpora lutea?
Effect of oxygen tension on killing ofEscherichia coliby bovine polymorphonuclear neutrophil leucocytesin vitro
Authors: Goldberg John J. , Pankey J. Woodrow , Politis Ioannis , Zavizion Boris , Bramley A. John 
Published: June 2009

SUMMARYA batch fermenter modified to simulate the physical conditions of an inflamedv. uninflamed mammary gland was utilized to evaluate the effect of oxygen tension on killing ofEscherichia coliP4 by bovine polymorphonuclear neutrophil leucocytes. Leucocytosis was simulatedin vitro4 h after inoculation withEscherichia coliby adding bovine neutrophils isolated from peripheral blood to the culture medium. Experiments were conducted at 39°C in UHT treated milk. At micro-aerophilic oxygen tension (oxygen partial pressure, 3·11kPa), bacterial numbers declined during the first hour following addition of the neutrophils. Oxygen tension declined rapidly following PMN addition. Once oxygen was depleted, neutrophil activity was presumably diminished andEsch. colinumbers began to increase. Under anaerobic conditions (oxygen partial pressure, 0·17kPa), no reduction in population was observed. Photomicrographs taken at the time of neutrophil addition and at subsequent time intervals demonstrated a specific association between neutrophils and the pathogen. Subsequent lysis of neutrophils associated withEsch. coligrowth was seen coincident with oxygen depletion.