bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human β-casein
Authors: Greenberg Rae , Groves Merton L. 
Published: June 2009

SUMMARYHuman β-casein occurs in multiphosphorylated forms having the same amino acid composition but with 0–5 phosphate groups/molecule. Sequence analysis was used to determine whether each of the phosphorylated forms is a mixture of species having a certain number of phosphate groups randomly distributed or whether each form contains phosphate groups on specific seryl or threonyl residues. It was found that forms containing 2, 4 and 5 phosphate groups/molecule are homogeneous with respect to their phosphorylation sites. The monophosphorylated form, however, is a mixture of equal amounts of species phosphorylated at residues 9 or 10.
The determination of the zeta potential of casein micelles
Authors: Darling Donald F. , Dickson John 
Published: June 2009

SUMMARYThe principle of moving boundary electrophoresis has been employed for the measurement of the electrophoretic mobility and subsequent calculation of zeta potential of bovine casein micelles. The zeta potential of casein micelles was observed to increase with increase in temperature (from 10 to 50 °C) and to decrease with decrease in pH. Heat treatment of milk between 90 °C/30 min and 135 °C/50 min had no significant effect on zeta potential. The zeta potential of casein micelles during rennet action decreases until all the κ-casein has been cleaved by the enzyme.The results of this study indicate that electrostatic interactions alone are not sufficient for an understanding of the absolute stability of casein micelles.
Covalent bonds formed in proteins during milk sterilization: studies on caseins and casein peptides
Authors: Lorient Denis 
Published: June 2009

SUMMARYFormation of covalent bonds at milk sterilization temperatures was studied using caseins and casein peptides. At 120°C lysinoalanyl residues produced even at pH 7·0 were derived from intra-molecular interactions between phospho-serine and lysine; the conditions of formation were determined. It was also found that the formation of isopeptidic cross-links was significant with conditions more severe than those used for milk sterilization.
Effect of free fatty acids on the amount of deposit formed from milk on heated surfaces
Authors: Al-Roubaie Sami M. , Burton Harold 
Published: June 2009

SummaryIndividual fatty acids were added to liquid skim-milk and to reconstituted dried skim-milk in concentrations similar to those produced by natural lipolysis, and their effects on deposit formation from the milk on a heated surface were determined. The use of reconstituted dried skim-milk considerably improved the reproducibility of the results. Butyric, caproic and caprylic acids did not influence the amount of deposit formation. Capric acid had a marked effect in reducing deposit at low concentrations: the effect of ageing of milk in reducing deposit formation is thought to be due to capric acid development. Laurie, myristic and palmitic acids had a slight effect, increasing deposit formation, while stearic acid caused a considerable increase. Capric acid was found to adsorb to the casein micelles in milk, and it may therefore act by interfering with casein aggregation during the build-up of deposit.
A comparison between ryegrass and cocksfoot hay for milk production
Authors: Castle M. E. , Drysdale A. D. , Watson J. N. 
Published: June 2009

SummaryFour hays were compared in a 20-week winter feeding trial using eight Ayrshire cows. The hays consisted of either ryegrass (variety S 24) or cocksfoot (S 37), and each grass was cut either on 23–25 May (cut 1) or 3 weeks later on 13–15 June (cut 2). The ryegrass cut 1 hay (R1) had the highest content of digestible dry matter, the cocksfoot cut 2 hay (C2) had the lowest content. The ryegrass cut 2 hay (R2) and cocksfoot cut 1 hay (Cl) had intermediate values. On all the treatments the cows were offered 19 lb of hay daily plus concentrates at the rate of 3½ lb/10 lb of milk.The consumption of concentrate dry matter was almost identical on the four treatments and averaged 10·1 lb per cow per day but the intake of C2 was slightly, but significantly, below that of the other three hays. On average the hays contributed 62% of the total daily intake of dry matter. The total weight of starch equivalent (S.E.) eaten per day increased from 13·6 lb on the C2 treatment to 15·2 lb on the R1 treatment.The mean daily milk yields on the four hay treatments were: Rl, 32·1 lb; R2, 29·9 lb; C1, 30·5 lb and C2, 26·9 lb. On average the milk yields from cut 1 hays were significantly higher than the yields from cut 2 hays, and the yields from the ryegrass were significantly higher than the corresponding yields from the cocksfoot. The differences in milk composition between treatments were small. The fat percentage of the milk on C2 was higher than that with the other three hays, and with the higher yielding cows the solids-not-fat (S.N.F.) and crude protein percentages were significantly higher on R1 than on the other hays.It is concluded that the nutritional value of ryegrass hay is superior to that of cocksfoot hay for milk production.
The manufacture of ‘normal’ and ‘starter-free’ Cheddar cheese under controlled bacteriological conditions
Authors: Perry K. D. , McGillivray W. A. 
Published: June 2009

SummaryA relatively simple method is described for the manufacture of Cheddar cheese under controlled bacteriological conditions. This method is shown to give the required degree of asepsis and to permit the manufacture of cheeses of uniform and normal composition.The composition, bacteriology and flavour of 28 ‘aseptic’ cheeses and of 18 ‘nonaseptic’ control cheeses made by this method are discussed. Thirty-nine of these cheeses were made using singly 3 strains of Streptococcus cremoris and 2 strains of Str. lactis as starter and 7 were made using gluconic acid lactone in place of starter. The effect of inoculating the milk with a strain (25·2) of ‘Lactobacillus plantarumcasei’ and a strain (L1) of micrococcus was also investigated.
A thermoduric strain ofStreptomyces albus, isolated from Cheddar cheese
Authors: Fryer T. F. , Sharpe M. Elisabeth 
Published: June 2009

SummaryA strain ofStreptomyces albus, presumed to have originated in raw milk, was found in large numbers in a pair of experimental cheeses. The numbers of streptomyces in both cheeses remained constant over the 4-month period of sampling and a comparison of the numbers obtained from cheese dissolved in citrate with and without mechanical aid revealed no differences, suggesting that the streptomyces was present in the conidial state. The heat resistance of mycelium and of conidia was determined at 62·7 °C (145 °F) and 71·7 °C (161 °F). The mycelial cells showed no resistance to either temperature, there being 100% kill after 15 min at 62·7 °C and 17 sec at 71·7 °C. The conidia, however, were very much less affected after 2 h at 62·7 °C, and 3% remained viable even after 30 min at 71·7 °C. Although the strain was found to be proteolytic, lipolytic and saccharolytic, it appeared to be inactive in the cheese, being present in the conidial state.
The recovery of small numbers of Staphylococcus aureus infused into the bovine teat cistern
Authors: Newbould F. H. S. , Neave F. K. 
Published: June 2009

SummarySmall volumes of milk each containing an average of less than 10 colonyforming units of Staphylococcus aureus were injected into the teat cisterns of 39 quarters of 10 cows.Typical staphylococci were recovered from only 14 quarters following overnight incubation of milk stripped manually from each quarter 10 min after injection. There was an inverse relationship between the total leucocyte count of the milk taken from the quarter before infusion and recovery of staphylococci.From 4 of 8 quarters from which Staph. aureus could not be recovered by enrichment it was possible to recover the organism by centrifuging the milk and culturing the deposit of leucocytes and bacteria.It is suggested that release of ingested staphylococci from defunct phagocytes may be important in initiation of infection, failure of antibiotic therapy and recurrence of infection.
The response of the bovine mammary gland to an infusion of staphylococci
Authors: Newbould F. H. S. , Neave F. K. 
Published: June 2009

SummarySmall numbers of bovine staphylococci, usually less than 30, were infused into the teat cistern of 17 cows secreting less than 100 000 leucocytes/ml milk. Infection was assumed to have occurred if the organisms multiplied sufficiently to be recovered in the foremilk and inflammation was regarded as demonstrated if there was an increase in leucocytes. If the staphylococci were recovered at the 1st post-infusion milking they were consistently recovered thereafter and inflammation always followed but was never evident at the 1st post-infusion milking. Inflammation was usually evident by the 3rd but in one instance was delayed to the 11th post-infusion milking. There was never inflammation in the absence of infection. When there was a high probability that the infusion contained one organism or more, infection occurred in 2 of 10 quarters infused with coagulase-negative staphylococci and 23 of 25 quarters infused with coagulase-positive staphylococci.A significant positive relationship was found between the number of staphylococci found at the 1st post-infusion milking and the number of leucocytes at the 3rd postinfusion milking.
Changes in moisture distribution caused by partial reworking of butter shortly after churning
Authors: Dolby R. M. 
Published: June 2009

SummarySamples of butter were reworked at various times after removal from the churn, either in a laboratory mixer or by pressing between a microscope slide and cover glass. Moisture distribution was studied by microscopic examination and by indicator papers.Reworking within 30 min of completion of the original working caused no change in moisture distribution but delayed reworking caused aggregation of water droplets. The further the setting of the butter had proceeded before reworking, the greater was the extent of aggregation.Cream-cooling treatments which resulted in a softer butter delayed or decreased the aggregation of droplets caused by reworking.A theory is suggested relating changes on reworking with the formation of a crystal structure on setting.
Anti-O chaining titre in colostral serum from cows infused prepartum with Salmonella Pullorum-H
Authors: Porter R. M. 
Published: June 2009

SummaryA high anti-O chaining titre against Salmonella pullorum-H can be obtained in colostral serum when the killed antigen is introduced into the mammary gland during the dry period. A significant titre, several times the normal level, is maintained in the milk serum for 3 weeks postpartum. There was a definite residual titre in the milk serum of non-infused cows against the O and H antigens of Salmonella typhosa and the O antigen of S. pullorum-H.
A new approach to the measurement of the quantitative effects of inherent and environmental factors on the composition of the milk of individual cows and of herds, with particular reference to lactose content
Authors: Walsh J. P. , Rook J. A. F. , Dodd F. H. 
Published: June 2009

Summary(1) A tentative scheme is proposed for the quantitative estimation of the effects of various factors on one major milk constituent, lactose, from analyses of the milk of individual cows within herds. The potential lactose content in the milk of individual cows is predicted from the observed potassium-to-lactose ratio in the milk, and the difference between the predicted potential and the actual lactose content is partitioned into fractions that are attributed to effects due to age, inter-quarter difference and changes with stage of lactation. The scheme was applied to 2 commercial herds, one (herd A) producing milk of low and the other (herd B) milk of normal SNF content.(2) Lactation mean values for fat, SNF and lactose contents of the milk of individual cows showed a wide range of the same order in each of the 2 herds. Of the mean difference in SNF percentage of 0·30 between the herds, 0·14, or 47%, was due to a difference in lactose content.(3) The predicted potential milk lactose content of the cows in the 2 herds ranged from 5·04 to 5·66 (g/100 g milk water). Herd mean values were 5·394 for herd A and 5·244 for herd B.(4) Herd mean values for the effect on the lactose content (g/100 g milk water) of age, of changes with stage of lactation and of inter-quarter difference were −0·127, −0·080, and 0·073 respectively in herd A, and −0·197, −0·058 and −0·078, respectively, in herd B.(5) The relative importance of the various factors in accounting for differences between the herds in the lactose content of their bulk milk were: predicted potential lactose content 61%, effect of age 28%, effect of changes with stage of lactation 9% and effect of inter-quarter difference 2%.(6) The errors attached to the estimation of potential milk lactose content and the effects of age, of changes with stage of lactation and of inter-quarter difference are discussed.
The effects of mono-unsaturated and saturated fatty acids in the diet on milk-fat secretion in the cow
Authors: Steele W. , Moore J. H. 
Published: June 2009

SummaryThe effects of the addition of either 5 or 10% ‘oleic acid’ (78% pure) or 10% of a mixture of saturated fatty acids (64% palmitic acid, 31% stearic acid) to the dietary concentrate mixture on the yield and composition of the milk and milk fat and on the pattern of fermentation in the rumen were investigated in a feeding experiment with 8 cows in mid-lactation. The concentrate mixtures were given with a high-roughage diet that supplied 9·1 kg of hay/day.The addition of 5% ‘oleic acid’ to the concentrate mixture resulted in increased yields of milk and solids-not-fat (SNF); the percentage of fat in the milk was decreased but the yield of milk fat was unaltered. The addition of 10% ‘oleic acid’ to the concentrate mixture decreased both the yield and percentage of fat in the milk. In contrast, the concentrate mixture containing 10% of the mixture of saturated fatty acids increased the yield of milk fat.When the concentrate mixture containing 5% ‘oleic acid’ was given to the cows, the yields and percentages of the fatty acids from 4:0 to 16:0 (except 12:0) in the milk fat were decreased, but the yields and percentages of 18:0 and 18:1 were increased. Similar but more pronounced effects on the yields and percentages of the fatty acids from 4:0 to 16:0 (except 12:0) in the milk fat were observed when the cows were given the concentrate mixture containing 10% ‘oleic acid’, but under these dietary conditions the yield and percentage of only 18:1 in the milk fat were increased. The addition of the mixture of saturated fatty acids to the concentrate mixture decreased the percentages of the fatty acids from 4:0 to 14:0 (except 12:0) in the milk fat but decreased the yields of only 10:0 and 14:0; the yields and percentages of 16:0 and 18:1 were increased.When the cows were given the concentrate mixture containing 5% ‘oleic acid’ there was a small but significant decrease in the acetic acid:propionic acid ratio in the rumen liquor. A similar but more pronounced change in the acetic acid:propionic acid ratio in the rumen liquor was observed when the cows were given the concentrate mixture containing 10% ‘oleic acid’, but in this instance there was a significant reduction in the concentration of total volatile fatty acids in the rumen liquor. Apart from a small increase in the relative proportion of propionic acid, the addition of the mixture of saturated fatty acids to the concentrate mixture had no effect on the concentrations of volatile fatty acids in the rumen liquor.
The responses in milk solids-not-fat and protein contents to improved feeding of cows receiving winter-stall diets and underfed for varying periods
Authors: Wright J. A. , Rook J. A. F. , Wood P. D. P. 
Published: June 2009

SummaryThe effect of varying periods of energy undernutrition on milk yield and composition was determined in 30 British Friesian cows receiving a typical winterstall diet. An absence of steaming-up, and underfeeding from the beginning of lactation, depressed both milk yield and solids-not-fat (SNF) content, especially in early lactation. Initially the reduction in milk SNF content was accounted for mainly by a loss in lactose content, but as lactation progressed this effect lessened and an effect on milk protein content was established. Protein content was similarly depressed by underfeeding in mid-lactation. The restoration of normal feeding in mid-lactation after varying periods of underfeeding was associated with only small responses in SNF and protein contents.The effect of the type of basal diet and supplementary concentrates on the extent of the increase in SNF and protein contents in response to improved feeding was examined in 2 further experiments. Responses were in all instances small and it was concluded that with the diets commonly in use in Great Britain the provision during the winter period of supplementary concentrates, whatever their composition, is unlikely to give a marked improvement in milk SNF or protein contents.
Responses in rumen fermentation and milk-fat secretion in cows receiving low-roughage diets supplemented with protected tallow
Authors: Storry J. E. , Brumby P. E. , Hall A. J. , Johnson V. W. 
Published: June 2009

SummaryThe effects on rumen fermentation and milk-fat secretion of a dietary supplement of protected tallow given to 4 Friesian cows established on a low-roughage ration and with depressed milk fat is reported. The ratios of acetate to propionate in the rumen were unaffected by the supplement and remained typical of those associated with low-roughage diets in that the proportion of propionate was increased. The supplement produced almost complete recoveries in yield and content of milk fat without any increase in intramammary fatty-acid synthesis. The recoveries were due to transfer of about 20% of the total fatty acids of the tallow supplement. These results are discussed in relation to the effects of low-roughage diets on milk-fat secretion and it is concluded that in the ‘low-fat syndrome’ the capacity of the mammary gland to absorb preformed fatty acids is not impaired.
Studies on the heat stability of milk protein: I. Interconversion of type A and type B milk heat-stability curves
Authors: Sweetsur A. W. M. , White J. C. D. 
Published: June 2009

SummaryCoagulation time–pH curves with a coagulation-time minimum around pH 6·8 (type A curve) could progressively become type B (no minimum) as the heating temperature was decreased from 150 to 130°C. The short coagulation time that most milks have when pH is around 6·8 was found to be the result of a ‘premature’ coagulation, probably caused by calcium phosphate deposition on the larger caseinate micelles. This is followed by a second coagulation, not visually detected, that coincides with the coagulation time that would be expected if no coagulation-time minimum existed on the coagulation time-pH curve. The coagulation time of milks giving type A and type B curves may therefore not be comparable.Forewarming milk for 30 min at 80°C can introduce or accentuate a coagulationtime minimum when the milk is subsequently heated at a higher temperature. The effects of adding β-lactoglobulin, copper and N-ethylmaleimide on the heat stability of milk were examined and explanations proposed for these effects.
Water vapour sorption properties of dried milk baby foods
Authors: Varshney N. N. , Ojha T. P. 
Published: June 2009

SummaryWater vapour adsorption and desorption properties of spray- and roller-dried milk baby foods were determined by a dynamic method at 25, 35 and 45°C. The equilibrium moisture content increased with increase in relative humidity and decrease in temperature; values for the spray-dried milk baby food were higher than those for the roller-dried product. The desorption and adsorption isotherms exhibited hysteresis. The desorption isotherms were of sigmoid shape: the adsorption isotherms were of similar shape except for a region of discontinuity. The relative humidity at which this discontinuity occurred depended on the temperature at which sorption was determined. Monomolecular moisture contents and latent heat ratios are reported.
Changes during storage in stability and composition of ultra-heat-treated aseptically-packed cream of 18% fat content
Authors: Anderson M. , Brooker B. E. , Cawston T. E. , Cheeseman G. C. 
Published: June 2009

SummaryThe stability of homogenized ultra-heat-treated (UHT) aseptically-packed cream of 18 % fat content when added to hot coffee was indirectly monitored in 10 batches of cream, stored for 10 weeks at different temperatures. A tendency to coagulate under standard conditions (instability) is known as feathering. Stability was determined by a procedure in which acetate buffer instead of coffee solution was used as the test solution. The distribution of components between the fat and aqueous phases of the stored cream was also monitored. Feathering score (stability) decreased during storage but was not accompanied by any increase in non-protein nitrogen levels. The amount of casein and Ca in the fat phase of the cream increased with time and was inversely related to feathering score. Some batches of cream contained 0·1 % Na2CO3and 0·1 %Na citrate as stabilizers and these additions were found to improve feathering scores early in the storage period. Initially, the fat phase of these creams contained less casein and Ca than those without the additives, but after 10 weeks the differences in feathering score and in casein and Ca distribution, between the 2 types of cream diminished. Examination by electron microscopy showed that casein micelles were associated with fat globules, apparently linking several globules together, which was less in the creams containing additives, but after 10 weeks the appearance of all creams was similar. Electrophoretic separation of the fat globule membrane (FGM) proteins by SDS-polyacrylamide-gel electrophoresis showed that casein was the principal protein component, but that β-lactoglobulin and native FGM proteins were aslo present.
Progressive changes in individual milk protein concentrations associated with high somatic cell counts
Authors: Anderson M. , Andrews A. T. 
Published: June 2009

SummaryProgressive changes in the concentrations of milk protein components were followed after infusions ofStreptococcus agalactiaeor bacterial endotoxin into different quarters of individual cows. Both types of infusion produced similar increases in somatic cell count and resulted in similar changes in milk proteins, although the effects of the endotoxin infusion lasted for a shorter length of time.The treatments had little effect on α-lactalbumin and β-lactoglobin concentrations, but serum albumin and immunoglobulin (Ig) concentrations increased markedly. The greatest effect on serum albumin was after the endotoxin infusion and on Ig after theStr. agalactiaeinfusion. Changes in the individual globulins indicated that passive transfer of blood proteins to milk could not account for the observed increases in IgM and IgA.αs1-Casein and β-casein concentrations were reduced and inversely related to somatic cell count during the immediate post-infusion period, and this was accompanied by an increase in para-κ-casein. Para-κ-casein was not detected in pre-infusion or post-recovery milk samples. The decrease in β-casein was greater than that of αs1-casein. Casein concentrations returned to pre-infusion levels 2 d and 5 d after the endotoxin andStr. agalactiaeinfusions respectively.The possibility that proteolytic enzymes are partly responsible for the changes in casein concentration is discussed.