bluuebunny/crossref_metadata_2025_split huggingface dataset:
Milk composition and yield of the black Bedouin goat during dehydration and rehydration
Authors: Maltz Ephraim , Shkolnik Amiram 
Published: June 2009

SummaryMilk composition and yield were measured in the black Bedouin goat during 4 d of dehydration followed by 2 d of rehydration. During this time the goats were exposed to strong solar radiation with no access to shade; all of these conditions occur commonly in the desert. Milk yield, initially similar to that found in the desert, was maintained during the first 2 d of dehydration, fell to 35% of the initial value over the third and fourth days and recovered fully during 2 d of rehydration. As yield fell, milk osmolality, and milk fat and protein concentrations rose. During rehydration all 3 fell once more, but whereas osmolality finished below initial values the concentrations of fat and protein remained higher than before dehydration. The milk remained isosmolar with plasma throughout. Total yields of milk solids and milk water during the whole experimental period were 70 and 67% of normal respectively and normal growth of the young was not disturbed.
Chemical composition and coagulating properties of renneted Friesian milk during the transition from winter rations to spring grazing
Authors: Grandison Alistair S. , Ford Graeme D. , Owen A. Jane , Millard David 
Published: June 2009

SummaryThe chemical composition and rennet coagulation properties at pH 6·4 of milks from 2 commercial herds of Friesian cows were monitored during the change from winter diet to spring grazing. There was considerable variation both in composition and in coagulation properties during this period. There were significant trends for increasing concentrations of casein, Na and lactose, and decreasing concentrations of fat, citrate, K and Mg following the change. Many correlations occurred between concentrations of components, some of which may have physiological significance. Coagulum strength increased after the change to spring grazing and was related to the concentrations of casein, citrate and some of the minerals. Syneresis time did not follow any trend during this period, but was significantly related to concentrations of fat, Na and K. Rennet clotting time did not follow a significant trend immediately after the dietary change, but tended to increase as the summer progressed; it was significantly related to concentrations of Ca, PiNa and K, as well as to the original pH of the milk. When the concentration of lactose in milk was adjusted, variations in lactose concentration did not affect the coagulation properties of milk.
Application of polymer cross-linking theory to rennet-induced milk gels
Authors: Johnston Donald E. 
Published: June 2009

SummaryA general theory of gel formation by cross-linking of polymer molecules, orginally developed for the study of rubber vulcanization, is proposed as a model for milk gel formation. The model divides gel formation and development into 4 stages, an enzymic and a non-enzymic stage preceding gelation, then a stage of material transition from the sol to the gelled state and a stage of increase in gel strength due to internal cross-link formations. The 2 post-gelation stages overlap to a variable degree depending upon particular circumstances. Gel formation and properties are interpreted in terms of the number of initial units which combine to form the gel and the number of cross-links eventually formed by each unit. When combined with a kinetic expression for the rate of cross-link formation the time course of gel shear modulus development or of the incorporation of material into the gel may be predicted. The classical asymmetric sigmoid shape of gel shear modulus development curves results from the third stage of material transition into the gel, which in turn depends upon the number of cross-links eventually formed by each initial unit. The modulus of mature gels is found to depend upon the square of material concentration, and gel breaking strength is found to be proportional to the modulus, in agreement with the predictions of the theory.
A microassay for the syneresis of cheese curd
Authors: Pearse Martin J. , Mackinlay Antony G. , Hall Robert J. , Linklater Peter M. 
Published: June 2009

SummaryA micro scale syneresis assay, using the natural optical density of the whey released as a trace, is reported. This assay is suitable for use with raw, reconstituted skim-milk (RSM) or artificial milk. Using RSM the reproducibility and accuracy of the method compared favourably with larger scale laboratory assays. When the method was used to investigate the syneresis properties of artificial micelle milk (AMM), the rate and extent of syneresis and response to a major variable such as pH were very similar to those of RSM. This suggests that the assay used in conjunction with AMM is suitable for investigating the mechanism of syneresis at a molecular level.
Changes in viscosity of processed creams during storage at 5 °C
Authors: Langley Keith R. 
Published: June 2009

SummaryThe viscosity of heat treated creams increased with time (t). The rate (k) was dependent on homogenization pressure, fat content and heat treatment temperatures. Viscosity and its rate of increase could be related by the expressions:log η = log η0 + kt(where η0 is the viscosity at t = 0),log η0 = a1 + b1φ/d(where φ is the fat volume fraction, d is the globule diameter) andk = a2 + b2φ/d.Different values of a1b1a2 and b2 were found for homogenized and unhomogenized creams.
Effect of inclusion of different forms of dietary fatty acid on the yield and composition of cow's milk
Authors: Banks William , Clapperton John L. , Girdler Anne K. , Steele William 
Published: June 2009

SummaryIn addition to a control diet, lactating cows were offered saturated fatty acid mixtures in three forms, free acids, free triglycerides and protected triglycerides, i.e. triglyceride encapsulated within a protein matrix which was cross linked by exposure to formaldehyde. Relative to the control diet, all three supplements increased milk yield. However, only the free fatty acids gave rise to increased yields of the three major milk components. The free fat and the protected fat caused significant increases only in the lactose yield. The different effects of the supplements on the yield of milk fat are suggested to be due to the types of long chain acid reaching the mammary gland rather than to any change in rumen activity. Changes in the concentrations of the soluble multivalent ionic constituents of the milks were consistent with this conclusion.
Isolation and characterization of heat stable proteinases fromPseudomonasisolate AFT 21
Authors: Stepaniak Leszek , Fox Patrick F. 
Published: June 2009

SUMMARYPseudomonasstrain AFT 21 produced three heat stable extracellular proteinases in milk and nutrient broth at 7 or 21 °C, but the proportions depended on medium and cultivation temperature. The three proteinases were EDTA- ando-phenanthroline-sensitive metalloenzymes and were not inhibited byN-ethylmaleimide or phosphoramidon. Proteinases I and II showed maximum activity at pH 7–7·5 and proteinase III at pH 8·5. All three enzymes showed maximum activity at 45–47·5 °C, but had relatively high (19–27% of maximum) activity at 4 °C. They were unstable at 55 °C in phosphate buffer, pH 6·6, or synthetic milk ultrafiltrate (SMUF) containing 12 mmol Ca2+, but were stabilized by short preheating at 100 °C. They were extremely heat stable in both phosphate buffer and SMUF, pH 6·6, at 70–150 °C. Their D-values at 140 °C were 69, 54 and 80 s respectively. The Z-values forPseudomonasAFT 21 proteinase III in phosphate buffer and SMUF were 29·7 and 30·3 °C respectively; the corresponding activation energies for inactivation were 8·7 × 104J mol-1and 9·2 x 104J mol-1.
Lysin production by øC2(W), a prolate phage forStreptococcus lactisC2
Authors: Mullan W. Michael A. , Crawford Robert J. M. 
Published: June 2009

SUMMARYA bacteriophage, øC2(W), which attackedStreptococcus lactisstrains C2, ML3 and 712, is described. It had a prolate head and a non-contractile tail and produced large haloes around plaques. Infection of eight paired-strain cultures, each containingStr.lactisC2, with øC2(W) resulted in marked inhibition of acid production for six cultures. Direct phage–nonhomologous ‘host’ contact was not required for inhibition. Lysates of øC2(W) contained a phage-induced lysin. Evidence is presented that the inhibitory effect of øC2(W) against paired and multi-strain cultures is due to the lysis of phage-insensitive strains by phage lysin. An isometric phage, ø712, was shown not to produce such a lysin.
NADP-linked dehydrogenases in secreted milk
Authors: Grigor Murray R. , Hartmann Peter E. 
Published: June 2009

SUMMARYThe activities of glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, isocitrate dehydrogenase, malic enzyme, lactate dehydrogenase and malate dehydrogenase have been determined in secreted milk from sows, rats and rabbits. Within each species, although there was considerable variation in the absolute activities of these enzymes, the relative activities were similar to those observed for, or previously published for mammary homogenates. The only exception was milk glucose 6-phosphate dehydrogenase which tended to lose activity upon prolonged storage in the mammary gland. These results suggest that the pattern of milk enzymes can be an accurate reflection of that occurring in the mammary gland.
Effects on mastitis of overmilking in conjunction with pulsation failure
Authors: Mein Graeme A. , Brown Murray R. , Williams David M. 
Published: June 2009

SUMMARYHalf-udder comparisons were made using 56 cows for 2 months, in an experiment involving high bacterial challenge, to assess the combined effects of 5 min overmilking and pulsation failure (resulting from the use of shortened teatcup liners) on teat condition and mastitis. Only three new infections were confirmed in over 12500 quarter milkings in quarters milked with control liners (of 148 mm effective length) indicating little or no effect of prolonged overmilking in these quarters. A 3·5-fold increase in the new infection rate (NIR) based on bacteriological diagnosis alone (P < 0·01), or a 9-fold increase in NIR based on bacteriological diagnosis plus raised cell count and/or N-acetyl-β-D-glucosaminidase (P < 0·01), occurred in quarters milked with the same liners shortened to an effective length of 120–130 mm. The mean interval to infection or teat canal colonization (41 ν. 60 milkings), and for a quarter infection to be confirmed by other diagnostic tests (45 ν. 79 milkings) was significantly less in quarters overmilked with short liners. The results confirm that NIR increases whenever pulsation fails. Overmilking may increase NIR when it is associated with pulsation failure.
Determination of lactulose and soya oligosaccharides in infant formula milk feeds
Authors: Beach Richard C. , Menzies Ian 
Published: June 2009

SUMMARYA paper chromatography technique is described for the separation and quantification of minor sugars in infant formula milks. The precision and reliability of the technique are described. Infant milk feeds of various types were analysed and found to contain up to 11·4 mmol/l of the non-absorbed sugar lactulose. Soya derived feeds may contain a significant residue of non-absorbable oligosaccharides.
Studies on the heat stability of milk: II. Association and dissociation of particles and the effect of added urea
Authors: Dalgleish Douglas G. , Pouliot Yves , Paquin Paul 
Published: June 2009

SummaryThe sizes of the casein particles in milk heated at 130°C were measured as functions of heating time and of initial pH. The effect of adding 10 mM-urea to the milks was also studied. Turbidities of the milks before and after dispersing the caseinate particles in 8 m-urea/EDTA/β-mercaptoethanol were measured, the latter measurement giving an indication of the extent of covalent cross-linking. Urea was found to modify the behaviour of the milk: diameters of the caseinate particles were considerably altered, and the extent of covalent cross-linking was diminished. These results agree with the observation that more protein is solubilized from the casein micelles when urea is present, indicating that a competitive reaction scheme involving cross-linking in opposition to micellar dissociation may be responsible for the ultimate precipitation of milk by heat.
Effect of temporary food or water deprivation on milk secretion and milk composition in the goat
Authors: Dahlborn Kristina 
Published: June 2009

SummaryWhen four goats were subjected to total water deprivation for 48 h once in early lactation and once in mid lactation and their voluntary food intake and effects on milk secretion were observed, milk volume decreased and lactose and fat concentration increased during both periods. However, when the goats were then fed the mean of their own food intake at the two previous water deprivation experiments, and were left free access to water, it was found that decreased food consumption had only a minor influence on milk secretion. When six goats were subjected to 48 h of food deprivation and six to 48 h of water deprivation, milk secretion decreased, but the reduction was delayed and of smaller magnitude during water deprivation. During food deprivation lactose concentration decreased and the milk protein and fat increased; the fatty acid composition changed from a greater proportion of short-chain to more long-chain fatty acids. During water deprivation milk fat and lactose concentrations increased, and only after 44 h did a change from short-chain to a larger proportion of long-chain fatty acids become evident. These experiments indicate that not only food intake, but also water intake are concerned with milk production.
Whipping of creams from ultrafiltered milk
Authors: Scurlock Peter G. 
Published: June 2009

SummaryCreams containing 25–45% fat were made from whole milks which had been concentrated 2- to 5-fold by ultrafiltration. Each series of creams (from any one concentrate) was standardized with its own skimmed milk, giving creams with higher than normal protein contents. These were then pasteurized and cooled for at least 24 h before being whipped. Increasing the fat content of creams gave increased stiffness, an overrun (volume increase) that passed through a maximum, decreased serum leakage and shorter whipping time. Increasing the protein content gave increased stiffness, less serum leakage, reduced overrun and a whipping time that passed through a maximum. Low fat creams, and also creams containing high amounts of fat and protein, did not produce a satisfactory whipped product. However, 35% fat creams from 2-fold concentrated milks compared well with ordinary 38% whipping creams. By lowering the fat content of creams an increase in yield was obtained.
Effect of ultrafiltered milk and use of different starters on the manufacture, fermentation and ripening of Havarti cheese
Authors: Qvist Karsten B. , Thomsen Dorf , Høier Erik 
Published: June 2009

SummaryWhen Havarti cheeses were made from milk concentrated 5-fold using ultrafiltration (UF) and with a direct vat set type starter containingStreptococcus lactis, Str. cremoris, Leuconostoc cremorisandStr. lactissubsp.diacetilactis(i.e. a BD-type starter) their colour, texture, body, and flavour were equal to those of traditionally produced Havarti. The somewhat slower flavour development was associated with a retarded breakdown of protein. Although αs1-casein was almost completely broken down in Havarti cheese made with the ultrafiltration method (UF Havarti) and traditional cheeses after 120 d of storage, degradation of β-casein was retarded in UF Havarti. Rennet contents and numbers of starter organisms were similar in the two types of cheese and thus could not explain the difference in ripening rate.Str. lactissubsp.diacetilactiswas dominant in both UF and traditional Havarti cheeses when the BD-type starter was used. By varying the composition of the starter, large variations in the bacterial composition and citrate fermentation in UF Havarti cheeses were obtained. The BD-type starter gave the best organoleptic quality.
Effect of casein and β-lactoglobulin genotypes on renneting properties of milks
Authors: Pagnacco Giulio , Caroli Anna 
Published: June 2009

SummaryThe effects of αs1-, β-, κ-casein and β-lactoglobulin genetic variants on rennet clotting time, rate of curd firming and coagulum strength, measured on the individual milks of 306 Rendena cows by a lactodynamographic apparatus, were evaluated statistically, with simultaneous adjustment for environmental and physicochemical factors. The importance of genetic polymorphism was confirmed, especially for the main effects of casein loci: interaction among them was not found to be significant. For κ-casein, BB genotype showed the best coagulation parameters (lower rennet clotting time, a higher rate of curd firming and higher coagulum strength), with AB in an intermediate position for clotting time and rate of curd firming. However, for αs1-casein and β-casein, dominance and overdominance effects between alleles were observed. Herd by genotype interaction was also found to be significant (herd by β-casein) or close to significance level (herd by κ-casein). From the results of the analyses, suggestions for selection programmes have been made.
Subunit components of casein micelles from bovine, ovine, caprine and equine milks
Authors: Ono Tomotada , Kohno Hideaki , Odagiri Satoshi , Takagi Toshio 
Published: June 2009

SummarySubunit components of ovine, caprine and equine casein micelles were separated by gel chromatography using a TSK-G4000SW high-performance column and the subunit components of the fractions analysed and compared with bovine casein. Molecular weights of the casein complexes were determined by the combined use of high-performance gel chromatography and low-angle laser light scattering. The caprine and ovine caseins were separated into three peaks (F2, F3 and F4) which were similar to those of bovine casein with respect to composition and molecular weight (500, 100 and 23 K). These F2, F3 and F4 peaks consisted mainly of αs- and κ-casein, αs- and β-casein and β-casein respectively. The equine casein was separated into two components corresponding to F3 and F4 of bovine casein. These F3 and F4 peaks consisted mainly of αs- and β-casein and β-casein respectively. The molecular weight of equine F3 (850 K) was different from that of the other three species. The contents of F2 and F4 in these caseins were dependent on the contents of κ-casein and β-casein respectively.
Whipping properties of cream in relation to milk composition
Authors: Banks William , Clapperton John L. , Muir D. Donald , Girdler Anne K. 
Published: June 2009

SummaryDietary manipulation was used to produce a similar series of milks from both Friesian and Jersey cows. The gross compositions of the milks, the fatty acid (FA) composition of the milk fats, the distribution of molecular sizes in the triglycerides of the milk fat, the melting properties of the milk fats, and the whipping properties of creams containing 360 and 400 g fat/kg were measured. Changes in gross composition and FA composition were as expected from the use of dietary oil supplements, but it was established that the mathematical relation between 18:0 and 18:1 differed between breeds, the Jersey yielding a milk fat with a lower proportion of 18:1 for a given value of 18:0. Control diets free from added fat produced milk fats with essentially unimodal triglyceride distributions, whereas fatrich diets produced bimodal distributions. The slight differences in these distributions between breeds were merely a reflection of variations in FA composition rather than in synthetic procedures. Differences in the whipping properties of creams containing 360 and 400 g fat/kg were consistent with literature observations. Dietary manipulation had little effect on the whipping properties of creams derived from Friesian cows, but caused considerable changes in the corresponding properties of the creams from Jersey cows. The only property that behaved similarly in the creams from the two breeds was the butter time, i.e. the time taken for butter granules to form on prolonged whipping of the cream. A major determinant of the butter time appeared to be the proportion of the fat that was molten at the temperature at which the whipping experiments were carried out.
Fractional melting of hydrogenated milk fat
Authors: Banks William , Clapperton John L. , Girdler Anne K. 
Published: June 2009

SummaryHydrogenated milk fats have been subjected to a process of fractional melting. In five of the six samples, the procedure yielded two fractions, defined as oil/upper solid and lower solid fractions, whilst in the remaining sample, three fractions (oil, upper solid and lower solid) were obtained. The oil and oil/upper solid fractions were rich in short-chain fatty acids (FA) (4:0 and 6:0), whereas the lower solid fractions contained large amounts of long-chain FA (16:0 and 18:0). Triglyceride distributions reflected these differences in FA composition, the oil and oil/upper solid fractions being dominated by triglycerides with carbon numbers (CN) 36–38; the dominant CN for the lower solid fraction was 48–54. Melting spectra, obtained using differential scanning calorimetry, showed that the ability of the fractionation procedure to separate on the basis of melting properties ranged from excellent to relatively poor, depending on the type of milk fat.
Ion-exchange fast protein liquid chromatography: optimization of the purification of caseins using a non-denaturing detergent
Authors: St-Martin Maryse , Paquin Paul 
Published: June 2009

SummaryThe separation of bovine milk proteins by fast protein liquid chromatography has been studied by ion-exchange chromatography on Mono S and Mono Q columns. The use of a non-ionic detergent, octyl-glucoside, made possible the separation of the four major casein components (αs1, αs2, β and κ) as well as minor caseins on the Mono S column using urea-containing buffers at pH 3·5. There was, however, considerable overlap between the αs1 and αs2-casein peaks. A good resolution was obtained with a low concentration of urea (3·5 M) and detergent (0·1%). These conditions allowed the separation of casein components in their native state in less than 50 min. The purity of isolated κ-casein was further improved by a second separation on a Mono Q column.
Characterization of wild strains ofLactococcus lactissubsp.lactisisolated from Cabrales cheese
Authors: Mayo Baltasar , Hardisson Carlos , Braña Alfredo F. 
Published: June 2009

SummaryTwentyLactococcus lactissubsp.lactisstrains isolated from cheese made from raw milk have been, studied and compared with well known starter strains. Many of them produced acid bacteriocins resembling those of other lactic streptococci and their patterns of antimicrobial agent susceptibility were also similar to previously studied dairy strains. On the basis of their ability to clot milk they could be divided into two groups. Some strains were rapid fermenters, with highβ-phosphogalactosidase and proteolytic activities. The other group had lowβ-phosphogalactosidase activity and coagulated milk slowly, but seemed to have proteolytic activity. All the strains had plasmid DNA in amounts and sizes similar to starter strains. Aβ-phosphogalactosidase probe was constructed with plasmid DNA from aLc. lactissubsp.lactisNCDO 712 derivative. Southern hybridization located homologous sequences in chromosomal and plasmid DNA from the wild isolates that fermented lactose efficiently, but the degree of homology was lower than that observed between starter strains.