bluuebunny/crossref_metadata_2025_split huggingface dataset:
A model heat-exchange apparatus for the investigation of fouling of stainless steel surfaces by milk I. Deposit formation at 100 °C
Authors: Foster Carole L. , Britten Michel , Green Margaret L. 
Published: June 2009

SummaryA model heat-exchange apparatus was used to investigate the factors affecting deposit formation from milk on a stainless steel surface at 100 °C. The structure and composition of the deposits were determined by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and chemical analysis after solution in alkali. The effects of changing the pH, preheating and skimming of the milk were similar to those observed in a small-scale continuous ultra high temperature plant. The time course of deposit formation showed that a lag phase did not occur, but the deposit which formed after more than 45 min was more porous than that formed after shorter times. Most (50–90%) of the fresh deposit was readily removed by sonication, leaving a sublayer richer in minerais than the original. The results provide evidence for the two-layer model for deposit formation proposed by Tissier & Lalande (1986).
Effects of chromatographically pure bovine chymosin and pepsin A on cheese curd firmness
Authors: Andrén Anders , von Reedtz Christina 
Published: June 2009

SummaryThe effects of chromatographically pure bovine chymosin and pepsin A on cheese curd firmness have been investigated. The enzymes were studied in parallel experiments, using a Formagraph, under which the following parameters were tested and varied: reconstituted skim milk powder, bulk raw milk, CaCl2 addition, enzyme concentration and temperature. Chymosin had a slightly better rate of curd firming (P ≤ 0·001) and better curd firmness 30 min after gelling point compared to pepsin under all of the conditions investigated. However, as regards curd firmness in cheese manufacture, this difference is only a question of time, since pepsin will give the same degree of curd firmness of the cheesemilk as chymosin after some minutes. The biggest disadvantage with pepsin is its strong pH dependence, which can lead to very long gelling times and weak curd if the pH is too high and the rennet is dominated by pepsin.
Milk yield and mammary function in dairy cows milked four times daily
Authors: Hillerton J. Eric , Knight Christopher H. , Turvey Alan , Wheatley Stephen D. , Wilde Colin J. 
Published: June 2009

SummaryGroups of lactating cows and heifers were milked four times daily in two diagonally opposed glands for 4 weeks, and the effects on milk yield studied relative to twice-daily milked glands as controls. Mammary enzyme activities, in vitro synthesis rates of milk constituents and histological scoring were determined in mammary biopsy samples obtained at the end of this period. These were used for assessment of mammary function. Frequent milking increased milk yield only in the treated glands, the contralateral control glands continuing to decline in yield at ~ 2%/week. There was no significant difference in response between cows and heifers; the mean increase in yield was 10·4%. The rate of decline in milk yield tended to decrease with frequent milking, to ~ 1%/week. Consequently the yield of the treated glands continued to be elevated above that of the controls for some time after reversion to overall twice daily milking. Milk protein content was increased slightly by frequent milking. Mammary enzyme activities were ~ 18% higher in the treated glands than in the controls. Synthesis rates of lactose, casein and total protein were unaffected by milking frequency, but were all lower in the gland selected for the second biopsy, reflecting the reduction in milk yield caused by the first biopsy. DNA synthesis was increased by milking frequency, as were the size and number of epithelial cells in histological sections.
Effect of methionyl bovine somatotropin in a prolonged-release vehicle on milk production, hormone profiles and health in dairy cows
Authors: Škarda Josef , Markalous Evžen , Slaba Josef , Krejčí Petr , Škardová Olga , Zedník Jiří 
Published: June 2009

SummaryMilk production of dairy cows in 14 herds was increased by 3·8–32·1% by the administration of recombinant methionyl bovine somatotropin (bST) in a sustained-release vehicle at 14 d intervals at 40–94 d post partum. A greater response in multiparous than in primiparous cows was found in cows turned out to graze spring pasture. Administration of recombinant bST resulted in elevated plasma bST during the first 9 d after injection. Clinical characteristics such as respiration, heart rate and body temperature were unaffected by bST treatment, as were blood erythrocyte and leucocyte counts, haemoglobin concentrations and haematocrit values. Plasma levels of glucose, free fatty acids, urea and P, and serum alanine aminotransferase and aspartate aminotransferase were not affected by bST treatment, and acetone was not detected. No adverse effects of bST on general health, infection status of mammary glands, mastitis incidence and reproduction were found.
High-fat spreadable processed cheese for people with high blood cholesterol
Authors: Abou-Zeid Nadia A. 
Published: June 2009

SummaryPart of the raw cheese base used for manufacturing high-fat processed cheese spread Was replaced by cows' (C) or buffalo (B) butter residue at levels of up to 20%. These residues were produced during the conversion of butter to butter oil by traditional moderate (T) or severe (M) heat treatments. The hypocholesterolaemic properties of butter residues incorporated into processed cheese were tested with rats (serum and liver cholesterol) and human beings (serum cholesterol). When rats were given the control cheese with no butter residue there were significant increases in both serum and liver cholesterol compared with rats given stock diet. However, when part of the raw cheese base was replaced by butter residue these rises were reduced by amounts proportional to the level of butter residue. The hypocholesterolaemic properties of the residues were in order CT > BT, CM > BM, and incorporations of 10% CT, 15% BT, 15% CM and 20% BM were found to nullify the hypercholesterolaemic effects of control cheese and restore cholesterol levels to their normal values. A small human trial gave similar results. Incorporation of butter residue slightly affected the chemical composition of the cheeses. Fat content and pH were little different; however, cheeses with butter residue tended to have higher total protein but lower soluble protein, tyrosine and tryptophan, and total volatile fatty acids. Rheological properties were not altered significantly. Incorporation of butter residue improved the organoleptic properties, particularly flavour intensity. Storage at 5 °C for 2 months did not alter the organoleptic properties and changes in chemical composition followed the normal pattern.
Comparative study of the separation of casein from bovine, ovine and caprine milks using HPLC
Authors: Kaminarides Stelios E. , Anifantakis Emmanuel M. 
Published: June 2009

SummaryThe separation of cows', sheep's and goats' milk casein components by HPLC on a strong anion-exchange (P.L-SAX 8μ 1000A) column is described. During HLPC, whole caseins of the three kinds of milk behaved differently from conventional separations. The casein components of the three kinds of milk were well resolved under the Chromatographie conditions used. HPLC resolved the κ-caseins better than did ion-exchange chromatography on DEAE cellulose, and was particularly efficient in the case of goats' milk. Goats' and sheep's milks had almost similar Chromatographie profiles but these differed considerably from that of cows' milk. Caseins from the sheep and the goat were also similar in that a shallower NaCl gradient was required for the separation of casein components than for cows' milk.
Evaluation of khoa as a milk solids source in ice cream
Authors: Shakeel-Ur-Rehman  , Upadhyay Kunjbihari G. , Pandya Ajit J. 
Published: June 2009

SummaryThe performance of khoa, a local heat-concentrated milk product, as a milk solids source in ice cream was tested by replacing 250, 500, 750 and 1000 g/kg of the condensed whole milk in control ice cream. Proximate composition was little affected by the inclusion of khoa at any level tested. At levels of inclusion > 250 g/kg the viscosity of both fresh and aged experimental mixes was significantly (P < 0·05) increased compared with controls. Some mixes containing khoa appeared slightly off-white, but there were no overall differences from control. Control and experimental mixes were identical in whipping capacity and overrun. In organoleptic evaluation, the colour score of the ice creams declined significantly (P < 0·05) when 750 or 1000 g/kg of the condensed milk was replaced with khoa. Ice creams containing khoa were equivalent or superior to controls in flavour. In objective tests, the experimental ice creams showed significantly (P < 0·05) faster meltdown compared with control, but no differences were found in subjective assessments. We conclude that khoa can be used successfully as a milk solids source for ice cream without any serious adverse effects on quality, the only problem being the dull colour.
Triacylglycerol fatty acid composition of milk from periparturient cows during acute Escherichia coli mastitis
Authors: Massart-Leën Anne-Marie , Burvenich Christian , Massart D. Luc 
Published: June 2009

SummaryChanges in fat concentration and triacylglycerol fatty acid (TGFA) composition were studied in milk from six periparturient cows 1 d before and 20 d after an experimentally induced Escherichia coli mastitis in the fore and rear homolateral quarters. Opposite fore and rear heterolateral quarters remained uninfected and were used as controls. Milk was collected from all individual quarters during the experiment. The fat concentration in milk from infected quarters did not change, but total fat production decreased owing to reduced milk production after the Esch. coli challenge. In milk from the heterolateral uninfected quarters fat concentration rose significantly 48 and 72 h after induction of mastitis, the rise being concomitant with a decrease in milk production. Throughout the experiment similar changes in TGFA composition were observed for both infected and uninfected quarters. There was an increase in all the even, odd-numbered, iso and anteiso short-chain TGFA from day +6 on after induction of mastitis. There was little change in the composition of 16:0 and 18:0 fatty acids, while the long-chain unsaturated fatty acids decreased. Using multivariate analysis, the results are presented visually. The observed changes in the TGFA can be ascribed to changes normally observed in cows' milk soon after parturition.
Heat stability of homogenized milk: role of interfacial protein
Authors: McCrae Catharina H. , Hirst David , Law Andrew J. R. , Muir D. Donald 
Published: June 2009

SummaryThe role of interfacial protein in determining the heat stability of recombined milk was investigated by removing serum protein prior to homogenization and reincorporating it after homogenization. In addition, the surface protein composition of recombined fat globules was probed by analyses of protein load and by quantification of the individual surface protein components using FPLC. In the absence of serum protein, substantially more casein was bound to the fat surface during homogenization. Despite this, the detrimental effect of homogenization on heat stability did not occur when serum protein had been removed from the system. Reincorporation of serum protein after homogenization caused the heat coagulation time–pH profile to revert to a form very similar to that observed without removing serum protein from the system. Thus, adsorption of serum protein did not affect heat stability. It is more likely that heat-induced interactions of serum protein with surface-adsorbed casein promoted heat coagulation. Fat surface area rather than casein load affected these interfacial protein-protein interactions during heating.
Use of California Mastitis Test,N-acetyl-β-glucosaminidase, and antitrypsin to diagnose caprine subclinical mastitis
Authors: Maisi Päivi , Riipinen Inna 
Published: June 2009

SummaryAnalysis of 448 milk samples (11 herds) from caprine udder halves showed that microorganisms were isolated from 21·8% of the samples. California Mastitis Test (GMT) andN-acetyl-β-glucosaminidase (NAGase) were superior to antitrypsin in detecting subclinical infections. Coagulase-negative staphylococci and micrococci were the main species isolated from halves showing no clinical disease. Coagulase-positive staphylococcal infections were associated with a significant increase of all inflammatory parameters. Significantly increased CMT and NAGase occurred when streptococci, other staphylococci or micrococci were present. Infection within one half was reflected as an increase in the inflammatory parameters in the milk of the infected half as well as a slight increase in the inflammation parameters in the adjoining half.
Rapid separation of bovine caseins by mass ion exchange chromatography
Authors: Ng-Kwai-Hang K. F. , Pélissier J. P. 
Published: June 2009

SummaryThe rapid isolation of major bovine caseins in gram quantities was investigated. Whole casein was precipitated from individual cow's milk by adjusting the pH to 4·6 and the precipitated casein was suspended in 4·5 M urea (pH 8·0) containing 0·02 M imidazole and 0·03 M β-mercaptoethanol, and bound on a QAE Zeta Prep 250 cartridge. Stepwise elution with the urea/imidazole β-mercaptoethanol buffer and varying amounts of NaCl gave five well resolved peaks, which were identified by polyacrylamide gel electrophoresis and fast protein liquid chromatography to be pure γ-casein, κ-casein. β-casein, β-casein and αs-casein, respectively. The ion exchange cartridge was regenerated by flushing with buffer containing 0·50 Μ-NaCl followed by equilibration with starting buffer before separation of next sample. The time required to run each sample including cartridge regeneration and equilibration was 4 hours.
Characteristics of the autolysis of variants ofLactococcus lactissubsp.cremoris
Authors: Niskasaari Kaarina 
Published: June 2009

SummaryTwo slime-forming strains (T5and MLS96) and a non-slime-forming strain (HA)of Lactococcus lactissubsp.cremoriswere investigated for autolysis and optimal conditions for the autolytic process were developed. The rate of autolysis was maximal in exponential phase cells in 0·01 M-Na phosphate buffer, pH 6·5–7·5, at 30–45 °C. Autolysis of the native exponential phase walls was activated by trypsin and inhibited by lipoteichoic acid and cardiolipin. Decreased trypsin activation was found in intact exponential phase cells and no activation in stationary phase cells.N-acetylmuramylhydrolase action in the autolytic system ofLc. lactissubsp.cremorisstrains was indicated by the progressive release of reducing groups. No amidase or endopeptidase action was found. Great variation in the rate of autolysis of whole cells was observed between the two slime-forming strains. Intact cells of strain T5exhibited decreased autolytic activity, but a higher rate of autolysis of isolated exponential phase walls. Autolysins from strain T5walls exhibited lower hydrolytic activity against sodium dodecyl sulphate-treated walls of the other two strains as compared with strains MLS96 and HA. Quantitative analysis revealed higher protein and phosphorus and lower hexosamine and rhamnose in cell wall preparations of strain T5compared with the other two strains. Results suggest that the decreased rate of autolysis of strain T5cells may at least in part be caused by cell surface components other than cell-wall peptidoglycan. It is proposed that the difference in autolytic characteristics should be used as a criterion when selecting starter strains of lactococci (streptococci).
Formation of galactose during heat treatment of milk and model systems
Authors: Calvo Marta M. , Olano Agustin 
Published: June 2009

SummaryThe formation of galactose, lactulose and epilactose during heating of milk was studied. The concentration of these carbohydrates increased with pH and the severity of heat treatment. The presence of proteins reduced the amount of lactulose formed whereas it increased that of epilactose and galactose. The galactose in heated milks was derived from lactose degradation. Under the conditions studied, degradation of the Amadori rearrangement product did not result in the formation of galactose. The interaction between proteins and galactose increased the thermal stability of the monosaccharide.
Intracellular proteinase ofLactococcus lactissubsp.lactisNCDO 763
Authors: Muset Graciela , Monnet Véronique , Gripon Jean-Claude 
Published: June 2009

SummaryAn intracellular proteinase was purified fromLactococcus lactissubsp.lactisNCDO 763 after spheroplast formation from cell wall proteinase-deficient variants. The proteinase was active at pH 7·5 and 45 °C and affected by metalloenzyme inhibitors. Its specificity, determined on B-chain of insulin, was thermolysin-like. The B-chain of insulin was hydrolysed rapidly while hydrolysis of β-casein was slower. This enzyme has aMrof ∽ 93000.
Ovine lactoferrin: isolation from colostrum and characterization
Authors: Buchta Richard 
Published: June 2009

SummaryHighly purified lactoferrin was isolated from ovine colostrum by sequential purification on CM-Sephadex C-50 and Blue-Sepharose, with overall yield of 55%. The ovine lactoferrin was characterized by SDS-PAGE, its amino acid composition and N-terminal sequence to residue 30. Homology with bovine and human lactoferrins was greater than 80 and 50% respectively. Antibodies to ovine lactoferrin were raised in rabbits and used to develop an enzyme-linked immuno-sorbent assay (ELISA). The antiserum was not cross reactive with other colostrum proteins.
In vitroproteolysis and functional properties of reductively alkylated β-casein derivatives
Authors: Chobert Jean-Marc , Touati Abdelmadjid , Bertrand-Harb Catherine , Dalgalarrondo Michele , Nicolas Marie-Georgette , Haertle Tomasz 
Published: June 2009

Summaryβ-Casein amino groups were modified with aldehydes and dialdehydes via reductive alkylation at pH 8·0. The degree of alkylation was controlled by the amount of the alkylating reagent applied. The initial rates of α-chymotrypsin-catalysed hydrolysis of alkylated β-casein were inversely related to the size of the modifying group. Proteolysis of modified β-casein with trypsin (18 h) or with α-chymotrypsin (48 h) depended on the nature and size of the substituent applied. The measurements of tryptophan fluorescence indicate that the modifications also induced conformation change. Solubilities of methyl-, ethyl- or benzyl-β-casein slightly increased; solubilities of β-casein dialdehyde derivatives were significantly lower than that of native β-casein. Emulsion stability of methyl- or ethyl- β-casein was higher than that of native β-casein in the acidic pH range. After modification with glyoxal, the emulsifying activity and the emulsion stability of β-casein decreased. The emulsifying activity of benzyl- β-casein was lower than that of native β-casein. Phthalylated β-casein displayed the poorest emulsion stability.
Size distribution and average size parameters of casein micelles determined by electron microscopy in bovine milk between pH 5·5 and 6·7. A comparison of several evaluation methods
Authors: Vreeman Henk J. , van Markwijk Bas W. , Both Paula 
Published: June 2009

SummaryThe conversion of the two-dimensional size distribution of casein micelles, observed by electron microscopy in a plane section, to the three dimensional distribution is discussed and the average size parameters evaluated by several methods are compared. It is shown that parameters containing the −1 moment of the two-dimensional distribution, i.e. Dn, the number of micelles per unit volume and the width of the size distribution, are sometimes uncertain. The occurrence of negative numbers in some of the classes of the distribution is discussed and remedies are suggested. Sections were made by freeze-fracturing skim milk samples; the pH of the milk was between 5·5 and 6·7.
Antioxidant activity of casein and Maillard reaction products from casein-sugar mixtures
Authors: McGookin Barry J. , Augustin Mary-Ann 
Published: June 2009

SummaryThe antioxidant activity of casein and Maillard reaction products obtained by reaction of casein with glucose or lactose was studied. Antioxidant activity was evaluated in a model System containing methyl linoleate with haemoglobin as a pro-oxidant. Casein was antioxidative and heating casein in the presence of glucose or lactose resulted in enhancement of antioxidant activity. The development of antioxidant activity in reacted casein–sugar mixtures was determined as a function of initial casein and sugar concentration. The observed antioxidant activity of reacted casein–sugar mixtures was due to casein itself and Maillard reaction products resulting from reacting casein with sugar.
Effect of recombinant chymosin on ewes' milk coagulation and Manchego cheese characteristics
Authors: Nuñez Manuel , Medina Margarita , Gaya Pilar , Guillen Ana M. , Rodríguez-Marín M. Asunción 
Published: June 2009

SummaryEwes' milk coagulation was significantly influenced by the type of rennet when recombinant chymosin produced by Kluyveromyces lactis was compared with two commercial calf rennets with declared chymosin contents of 55 and 70%. Recombinant chymosin and calf rennet with 70% chymosin exhibited similar thrombelastographic characteristics, and coagulated milk more rapidly than calf rennet with 55% chymosin. The type of rennet had no effect on Manchego cheese dry matter, pH or recovery of dry matter in cheese. N soluble at pH 4·6 was the only N fraction influenced by the type of rennet, with slightly higher levels for cheese made with recombinant chymosin or with calf rennet containing 70% chymosin than for that made with rennet containing 55% chymosin. No significant differences in rheological or sensory characteristics between Manchego cheese made with recombinant chymosin and that made with the calf rennets were detected.
Effects of some calcium-chelating agents on the physical properties of acid-set milk gels
Authors: Johnston Donald E. , Murphy Robert J. 
Published: June 2009

SummaryAcid-set milk gels containing up to 30 mM added hexametaphosphate, oxalate, citrate, EDTA or orthophosphate were prepared using gluconic acid-δ-lactone and their properties investigated. Increases in the apparent shear modulus were observed in the gels containing hexametaphosphate, oxalate, citrate and EDTA. The effect was maximum for hexametaphosphate-containing gels at ˜ 8 mM. Increases were also observed in the force required to break the gels, and for added hexametaphosphate the effect peaked at ˜ 5 niM. The ability of the gels to resist syneresis was investigated by a cut, tip and drain type test and by a centrifugation method. In both tests, resistance to syneresis was increased by added hexametaphosphate, oxalate, citrate and EDTA. The additions of anions were shown to cause disintegration of the micelles and release caseins to the serum. It is suggested that the improved homogeneity of casein distribution that results allows greater opportunity for protein-protein interaction during gel formation and leads to improved properties. Controlled micelle disintegration would therefore appear to offer promise for the development of improved or novel products.