bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of multiple regression analysis to sedimentation equilibrium data of αs1- and κ-casein interaction for calculation of molecular weight distributions
Authors: Nakai Shuryo , van de Voort Fred 
Published: June 2009

SUMMARYMultiple regression analysis was applied to sedimentation equilibrium data for determination of the molecular weight distribution (MWD) of model systems consisting of up to 3 components. Negative weight fractions which were frequently encountered during multiple regression analysis were forced to zero by sequentially eliminating from the regression matrix the corresponding molecular weights in order of the magnitude of negative t-values. The simplex optimization of Morgan & Deming (1974), modified by incorporating a prohibit–range– trespassing routine, was used to search for the best fit values for weight average molecular weights and relative concentrations of the components. This method almost quantitatively reproduced the molecular weights and concentrations of the original model systems. This quantitative information supplemented the multiple regression matrix to improve the resolution of MWD.A direct comparison using model systems revealed that the multiple regression method in conjunction with the simplex optimization routine was more quantitative than the linear programming method of Scholte (1969). When applied to mixtures of standard proteins (ribonuclease A; ovalbumin; γ-globulin and ovalbumin; γ-globulin; apoferritin), the simplex optimization routine yielded values for average molecular weights and relative concentrations of the component proteins which were in good agreement with the known values in the original mixtures.The MWD of αs1-k-casein mixtures at an ionic strength of 0.1 suggested that k-casein was readily dissociated to the monomer (or the dimer) and interacted with the monomer (or the dimer) of αs1-casein forming a complex of approximately 400000.
Headspace analysis of hard cheeses
Authors: Manning Donald J. , Moore Carolyn 
Published: June 2009

SummaryA method is described for the chromatographic analysis of the headspace of hard cheese. Among the cheeses examined were 12 commercial cheeses and 12 Cheddars made in the NIRD experimental dairy. The 12 commercial cheeses were Parmesan, Caerphilly, Stilton, Leicester, Double Gloucester, Cheshire, Gouda, Wensleydale and 4 varieties of Cheddar. It was found that those varieties containing low concentrations of sulphur compounds had little aroma and derived most of their flavour from taste and texture. The concentration of 2-pentanone was found to be a good indicator of maturity of Cheddar cheese.
260. An objective measure of the consistency of cheese curd at the pitching point
Authors: Blair G. W. Scott , Coppen F. M. V. 
Published: June 2009

1. A method is described for measuring the consistency of cheese curd during the scalding process which has been found satisfactory with Cheddar, Cheshire, Leicester, Double Gloucester, Caerphilly, Kingston and Derby cheese and is probably applicable to some other varieties.2. The property (W/h), taken as a criterion of consistency, can be measured within less than 1 min. and is highly correlated with moisture content except when abnormal scalding conditions produce an uneven distribution of moisture in the curd. The size of cut does not affect this correlation within wide limits, though both moisture content and W/h are regularly affected by size of cut until the curd is approximately ready to pitch, at which point both properties show unique values independent of size of cut.3. When the curd is nearing the pitching point, W/h measures the extent to which a standard cylinder of curd loses whey, the liquid being replaced in the solid structure by air. At an earlier stage in the scalding process the capacity of the curd to retain its shape under the force of gravity also affects W/h.4. Although the cheese-maker judges the consistency of curd suitable for pitching by a complex mixture of properties, it is believed that Wjh will serve as an effective single-value criterion of consistency, suitable for judging pitching time if the acidity is also known.
Action of rennin on α-, β- and γ-caseins
Authors: Lahav E. , Babad Y. 
Published: June 2009

SummaryWhole acid casein and α-, β- and γ-caseins were isolated and treated with rennin. Chemical, chromatographical and electrophoretical analyses were done on the caseins and on the products obtained from them after rennin treatment. Three different fractions were obtained which had some specific protective activity for the Ca-sensitive forms of α-, β- and γ-casein, respectively, and which differed in their chemical, chromatographical, and electrophoretical properties.It is suggested that each casein fraction in milk is associated with its own protective fraction which when released by the action of rennin, allows the casein to clot.
The effect of restricted grazing during a single day upon milk yield, milk composition and butterfat characteristics
Authors: Munford R. E. , Campbell I. L. , McDowall F. H. , Davey A. W. F. 
Published: June 2009

SummaryThe effects of depriving cows of pasture, for part or all of a single interval between the morning and evening milkings, on milk yield and composition have been investigated. The yields of milk and solids-not-fat, but not of fat, were reduced. The characteristics of the butterfat obtained at the first 2 milkings following grazing restriction differed markedly from those of cows allowed to graze normally.The changes observed suggested that the grazing restriction led to a temporary reduction in the supply of volatile fatty acids from the rumen and an increased utilization of fatty acids from body fat by the mammary gland.
A meter for measuring pulsation ratio in milking machines
Authors: Thiel C. C. , Akam D. N. 
Published: June 2009

SummaryA portable apparatus is described for indicating continuously as a measure of pulsation ratio the proportion of the cycle during which a liner is more than half open. With the machine set for milking, a probe with an electric switch which opens as the liner collapses is inserted in one liner, the others being closed with rubber bungs. The pulses of current from the switch are fed to a damping circuit so that the proportion of the cycle time during which current flows can be read on a meter. The problem of interpreting the various measures of pulsation ratio are discussed.
The nature and cause of seaminess in Cheddar cheese
Authors: Conochie J. , Sutherland B. J. 
Published: June 2009

SummaryMicroscopical and chemical studies of seaminess in Cheddar cheese revealed that the white lines or seams characteristic of the defect are sections through layers of crystals lying between the milled curd particles. The crystals were identified from their X-ray diffraction pattern and by their refractive index as calcium orthophosphate dihydrate, CaHPO4. 2H2O. On each side of the adjoining curd surfaces in affected cheese there is a zone about 20 μm thick of strongly contracted protein which is almost devoid of crystals.Adding sodium chloride to cheddared curd increased the quantities of calcium, phosphorus and water released. The increases were proportional to the amount of salt applied within the range 0–2·5 g NaCl per 100 g curd.The solubility of calcium orthophosphate was found to rise from about 0·0025 M in water to a maximum of 0·008M in 2 M sodium chloride solution.It is postulated that calcium and phosphate ions released from the curd into the seam crystallize in the form of CaHPO4. 2H2O as the solubility of the compound is lowered by diffusion of salt from the surfaces into the curd particles.
The influence of cream-processing methods on the rate of setting and final hardness of sweet cream butter
Authors: Wood F. W. , Dolby R. M. 
Published: June 2009

SummaryCream-cooling rates, cream-pre-cooling treatments (Alnarp) and seasonal changes in the chemical composition of butterfat were found to influence the setting rate of butter. Vacreator pasteurization, however, especially at high steam intensity, had the greatest effect. Comparative hardness values of butter made from platepasteurized and Vacreator-pasteurized cream were 1·5 and 2·9 kg and 4·4 and 8·3 kg at the end of ½ and 5 h, respectively, after the completion of working. The highest setting rate, which resulted in a hardness of 6 kg at the end of 30 min, was recorded for butter made from Vacreator-pasteurized cream which was rapidly cooled to 5 deg F below normal churning temperature and churned after holding for 30 min. Abrupt breaks noted in the setting curves of this rapidly setting butter lead to speculation that changes in the butterfat crystal form may be involvedIn general, the final hardness values of butter stored at 45 °F for 30–50 days were not greatly influenced by the setting rates observed at 55 °F during the 5-h period immediately after the completion of working. Exceptions to this observation were obtained when the cream was rapidly cooled to or slightly below churning temperature and also when the cooling of plate-pasteurized cream was delayed at 65 °F for 3–4 h before final cooling to the churning temperature.The causes of the differences observed in the setting and final hardness values of butters made from plate- and Vacreator-pasteurized cream were not determined and warrant further investigation.
The cell count of cow's milk and the micro-organisms cultured from the milk
Authors: Blackburn P. S. 
Published: June 2009

SummaryTotal and differential cell counts were made on a total of 26272 quarter samples of foremilk taken at fortnightly intervals from cows in the Institute herd during the 12 years 1953–1965, and the samples were also examined bacteriologically.The average cell count in each lactation up to the 7th was calculated.The average total cell count of samples from which no staphylococci, streptococci or coliform organisms were isolated increased from the 1st to the 7th lactations from 0·19 to 0·60 million cells/ml, and from the 2nd lactation onwards the increase was due entirely to an increase in the number of polymorphs. With infected samples, however, changes in the average total cell count were caused by changes in the numbers both of polymorphs and of cells other than polymorphs.The average total cell count of samples from which coagulase-negative staphylococci were isolated varied between 0·58 and 1·00 million/ml throughout the 7 lactations. For samples from which coagulase-positive staphylococci were isolated the cell count varied between 0·72 and 4·94 million/ml, the highest average total cell count occurring in the 5th lactation.The average total cell count of samples from which streptococci were isolated varied between 1·48 and 4·62 million cells/ml, the highest value occurring in the 2nd lactation.
Fat testing of composite Milk samples with the Milko-tester
Authors: McDowell A. K. R. 
Published: June 2009

SummaryWith 10-day composite milk samples the effect has been investigated of various preservatives, of variations in the method of preparing the composites and of the condition of the composites at sampling on Milko-tester results for fat content.The results for composites preserved with mercuric chloride agreed much more closely with the Werner Schmid results than did those for corresponding composites preserved with potassium dichromate, formaldehyde solution or paraformaldehyde.In composites preserved with mercuric chloride, prepared and held at ambient temperatures at 2 dairy factories, a small proportion contained destabilized fat when sampled at 98–103 °F and gave very low Milko-tester results in comparison with the Werner Schmid and Gerber results. After high-speed mixing of the composites at 115 °F the Milko-tester results were closer to, but still lower than, the Werner Schmid results.The average Milko-tester result for 133 composites free from destabilized fat when sampled at 98–103 °F was 0–099 ± 0.055% lower than the average Werner Schmid result. Results for 133 duplicate samples, which were also free of destabilized fat at 98–103 °F but which had not been swirled after the daily addition of fresh milk, were on average — 0.158 ± 0.076% lower than the Werner Schmid result. The Werner Schmid and Gerber results agreed well. The lowering of the Milko-tester result in the ‘swirled daily’ samples was due (a) to the effect produced by dissolving mercuric chloride in milk, (b) to slight fat hydrolysis, and (c) to some other factor, possibly fat oxidation. The further lowering of the Milko-tester result in the ‘non-swirled’ samples was due mainly to greater hydrolysis of the fat with production of higher fat acidities. Other composites, which were swirled daily but which were held at 38–40 °F gave on the average higher fat acidities and lower Milko-tester results than the ‘swirled daily’ composites held at ambient temperatures.A correction of +0.10% to the Milko-tester readings of all ‘swirled daily’ composites, preserved with mercuric chloride and in suitable condition for sampling at 98–103 °F, brought over 90% of the results to within ± 0.10% of the Werner Schmid results.The Milko-tester (Foss Electric, Hillerød, Denmark) is already in use in a number of countries for the rapid estimation of fat in milk. The fat content is read directly by a photometric measurement of the turbidity due to the fat globules after heating, homogenizing and diluting the sample with a protein-dissolving versene solution. The instrument has been found satisfactory for the routine testing not only of fresh milks but also of milks to which preservative has been added (Černá & Písecký, 1966; Murphy & McGann, 1967). Grubb (1966), however, reported that Milko-tester readings for samples preserved with potassium dichromate were lower after 14 days' storage.In the present paper the results are presented of an investigation into the suitability of the Milko-tester for fat testing of 10-day composite milk samples.
Factors affecting vacuum within the teatcup liner during milking
Authors: Thiel C. C. , Clough P. A. , Westgarth D. R. , Akam D. N. 
Published: June 2009

SummaryFactors associated with the milking cluster and the long milk tube which cause a diminished or a fluctuating vacuum within the liner of the teatcup assembly during simulated milking with an artificial udder fell into 3 groups. 1. Lower milk flow rates and admission of air at the clawpiece greatly decreased vacuum fluctuation within a pulsation cycle and increased the mean level of vacuum in the liner during that part of the cycle in which milk was flowing from the teat. 2. Larger bore of the short milk tube connecting the liner to the clawpiece, pulsation of the teatcup liners in pairs instead of all 4 together, and larger volume of the clawpiece bowl in the main decreased fluctuation in vacuum within the liner. 3. Larger bore and shorter length of the long milk tube connected to the clawpiece and decreased height above the outlet of the clawpiece to which the milk was raised mainly increased the mean vacuum in the liner during that part of the cycle in which milk was flowing from the teat.In a milking experiment with 75 cows mean overall fluctuations in milking vacuum within the liner in a pulsation cycle at peak flow were 11·5 and 4·8 inHg and corresponding mean levels of vacuum during that part of the cycle when milk was flowing from the teat were 11·75 and 13·0 inHg. There were no differences in milking performance of practical consequence.
Growth and proteinase production inPseudomonasspp. cultivated under various conditions of temperature and nutrition
Authors: Juffs H. S. , Hayward A. C. , Doelle H. W. 
Published: June 2009

SummaryA study was made of the formation of the extracellular proteolytic enzymes during the growth cycle of several species ofPseudomonascultivated under different conditions of temperature and nutrition. Proteolytic activity was not proportional to growth. Expressed per unit of cell dry weight, the proteolytic activity showed a peak in the early logarithmic phase which was greater in cultures grown at 3 than at 28°C. Proteolytic enzyme was not formed in the absence of organic nitrogen. Of 16 organisms studied,Pseudomonas aeruginosaATCC 10145 was the most prolific producer of proteolytic enzyme.
The composition of the milk of young and of old cows
Authors: Waite R. 
Published: June 2009

SummaryThe milk produced by old cows frequently contains a lower concentration of solids-not-fat (S.N.F.) than that of young cows, mainly because of a low concentration of lactose. This can result from mastitis or possibly from other factors associated with ageing. The composition of the milk of 2 groups of old cows has been compared with that of substantially disease-free first-lactation cows. A comparison has also been made between the milk from the 4 quarters of each cow.The first part of the work was done with 8 old cows and 4 first-lactation cows, and the milk was examined bacteriologically, cytologically and chemically at frequent intervals throughout the lactation. There was strong evidence that most of the difference in chemical composition of the milk of the old cows compared with that of the young cows was the result of mastitis, mainly subclinical. The milk from the old cows had a higher incidence of infection, a lower concentration of lactose and casein, higher concentrations of serum albumins, globulins and proteose-peptones and contained more total and polymorph cells. There was also some indication of another effect, not directly associated with disease in the current lactation, that led to a decrease in the lactose concentration of the milk of the old cows after about 80–90 days in lactation.In the second part of the work, the milk from 23 old and 8 first-lactation cows in 8 commercial herds was examined twice, once after 58 and again after 163 days in lactation. Milk of abnormal composition as a result of disease was produced by 30% of the quarters of the old cows at the first examination and by 62% of the quarters at the second examination.Some indication is given of the probable loss of milk and milk constituents that can be attributed to disease.
The sterilizing effect againstBacillus subtilisspores of hydrogen peroxide at different temperatures and concentrations
Authors: Swartling P. , Lindgren B. 
Published: June 2009

SummaryAn investigation was made of the death-rate ofBacillus subtilisspores in suspension in hydrogen peroxide concentrations of 10, 15 and 20% at 25, 50, 60, 70 and 80°C. Average logarithmic survival curves were plotted against normal time and death-rate constants andQ10values were calculated from the graphically determined decimal reduction times. This treatment of the experimental findings was found to be warranted in the temperature range 60–80°C. The first-order death-rate constant was ∽ 0·1 s−1for 10% hydrogen peroxide solution at 60°C and theQ10was about 1·6. Increases in the concentration from 10 to 15% and from 15 to 20% each gave an increase of about 50% in the rate constant. The application of these data to commercial practice is discussed.
Growth ofstreptococcus lactisin milk in a continuous fermenter
Authors: Linklater P. M. , Griffin C. J. 
Published: June 2009

SummaryMilk was added to a continuous fermenter to maintain a selected operating pH in the range 5·4–6·0, a fermentation system controlled in this way being called a pH-stat. Below pH 5·4 casein coagulated in the fermenter and on the pH electrodes. At pH 6·0 stirring inhibited the growth of the test culture,Streptococcus lactisC 10, but the inhibitory effect was reduced and the culture grew satisfactorily when the milk reservoir was sparged with 5% CO2in N2or with N2alone. The dilution rate was highest near pH 6·0, which was close to the optimum pH for the growth of the organism. The rate of production of lactic acid and of bacterial cells in the fermenter was highest at pH 5·4.
Properties of aseptically-packed UHT milk: casein modification during storage and studies with model systems
Authors: Andrews A. T. , Cheeseman G. C. 
Published: June 2009

SummaryStorage of aseptically packed UHT milk produced changes in the electrophoretic pattern of the milk caseins when the milk was stored at ambient or higher temperatures. Lower temperature storage at 4°C did not give rise to these changes.The alterations in electrophoretic properties of the caseins appeared to be due to the action of carbonyl compounds, produced by a Maillard type of reaction, which led to changes in the charge of the protein together with some degree of polymerization. These conclusions have been drawn from results obtained on model systems of casein-lactose subjected to various heat treatments, and on casein and milk treated with acetaldehyde.Changes in the sensitivity to calcium ions of individual caseins, whole casein and milk that had been subjected to various heat treatments or to treatment with acetaldehyde showed that all these different treatments gave rise to modified casein which, in general, became less sensitive to calcium. κ-Casein when treated alone rapidly lost its ability to protect αs1-casein from precipitation by calcium ions, while αs1-casein treated alone only gradually became more soluble in the presence of calcium. Thus, on treating whole casein there was evidence for a stability minimum when the protective ability of the κ-casein has been destroyed without a compensating gain in the stability of the αs1-casein.The importance of these changes in relation to the stability of UHT milks has not yet been elucidated but the results indicate that cross linking between protein chains and changes in calcium sensitivity occur during long-term storage.
Reproducibility of the electronic cell-count procedure for counting somatic cells in milk
Authors: Pearson J. K. L. , Greer D. O. , Stewart D. A. 
Published: June 2009

SummaryA series of experiments is described, outlining a study of 5 factors likely to influence the efficiency and reproducibility of a standardized method used for the electronic counting of somatic cells in milk. Samples containing cells covering 5 ranges from 250000 cells/ml to 1500000 cells/ml were used and the results analysed statistically.The residual error was given special consideration, and was found not to contribute to any significant degree to the accuracy of the method. Sample volumes of 0·5 ml and 0·1 ml used for counting were compared, and there was a decrease in accuracy using the smaller volume. The influence of individual technician skill was studied with 4 workers having differing degrees of experience, and no significant addition to the overall error was observed. The effect of agitating bulk tank milk for between 0 and 2 min before sampling was examined. Variations were considerable for agitation times of less than 1 min, but the recommended mixing time of 2 min was found to be adequate with milk quantities between 450 l and 2250 l (100 and 500 gal), and at the 5 cell-count levels chosen.The distributions of the cell counts at the 5 levels were found to be normal with the marginal exception of samples tested at 250000 cells/ml.All aspects of the technique, sample preparation, use and calibration of the Coulter Counter, etc, should be closely followed to ensure that no inaccuracies will result from inadequate maintenance of the machine or other equipment employed in the test.