bluuebunny/crossref_metadata_2025_split huggingface dataset:
The formation of complexes between whey proteins and carboxymethyl cellulose modified with substituents of increased hydrophobicity
Authors: Zadow J. G. , Hill R. D. 
Published: June 2009

SummaryThe precipitation of proteins from whey by modified carboxymethyl cellulose (CMC) was examined. Carboxymethyl cellulose containing acetyl, methoxyl or carboxymethyl secondary amides with iso-propyl, n-propyl, iso-butyl, n-butyl or cyclohexyl side chains precipitated more protein than did CMC of similar carboxyl content. This effect was greatest in CMC containing secondary amide groups. The increase in protein precipitation gained by introduction of secondary amide groups into CMC was no greater however than the increase obtained by introduction of a similar number of carboxymethyl groups into the polymer. Carboxyethyl cellulose did not form insoluble complexes with whey proteins under the conditions examined.
Metabolism of [14C]bicarbonate byStreptococcus lactis: identification and distribution of labelled compounds
Authors: Hillier Alan J. , Jago G. Richard 
Published: June 2009

SummaryStreptococcus lactisC10, grown in tryptone–yeast extract–lactose broth containing [14C] bicarbonate, incorporated radioactivity into the protein and nucleic acid fractions of the cell as well as into compounds which were excreted by the organism into the growth medium. Aspartic acid was the first compound to be labelled and was the only amino acid labelled in the cell protein. All 4 bases were labelled in the cell RNA. Aspartic, succinic and lactic acids were the radioactive compounds excreted into the growth medium.
Stereospecific distribution of fatty acids in bovine milk fat triglycerides
Authors: Parodi Peter W. 
Published: June 2009

SUMMARYPancreatic lipase deacylation was used to study the variation in distribution of the fatty acids at positionsn-2 of milk fat triglycerides of a series of butters and of the milk obtained from a cow on a restricted feeding regimen. Selected samples were analysed for stereospecific distribution of their triglyceride fatty acids which were found to be esterified in a non-random manner. The percentage of a fatty acid at positionsn-3 generally decreased with increase in the chain length of the acid; the reverse occurred at positionsn-1. There was no major variation in the stereospecific distribution of fatty acids throughout the year; the variation that did occur was exhibited mainly by the medium chain length acids. Variation was greater at positionssn-1 andsn-3 than at positionsn-2 and when the proportion of an acid varied at positionsn-1 it usually varied at positionsn-3 in the reverse manner.For the milk samples it was found that change in triglyceride fatty acid composition was not associated with random increases or decreases of fatty acids at the 3 stereospecific positions. With changing triglyceride fatty acid composition (6:0, 8:0, 10:0, 12:0, 14:0, and 16:0 decreasing and 18:1 increasing) the percentage of 6:0, 8:0, 10:0, 12:0, 14:0 and 16:0 acids at positionsn-3 decreased while the percentage of 18:0 and 18:1 acids increased. These changes were compensated for by changes in the opposite direction at positionssn-1 andsn-2.
Quantitation of αs1-casein aggregation by the use of polyfunctional models
Authors: Dalgleish Douglas G. , Parker Thomas G. 
Published: June 2009

SUMMARYA model for the coagulation of Ca2+ αsl-caseinate is described wherein the casein molecules are considered to aggregate as polyfunctional units. The functionalities on the protein molecules are produced as a consequence of the binding of Ca2+, and the multiple equilibria which are established during this binding produce a distribution in which not all casein molecules have the same functionality. The theory is compared with experimental data of the precipitation reaction, and is shown to provide an adequate quantitative description of the precipitation.
The voluminosity of bovine casein micelles and some of its implications
Authors: Walstra Pieter 
Published: June 2009

SUMMARYA comparison of literature results on the voluminosity of casein micelles yields large differences, largely related to the method of determination. After applying some corrections, methods based on hydrodynamic radius yield a value of roughly 3·9ml/g dry casein, other methods (microscopy, sediment volume) about 2·2. Roughly half of the discrepancy can be explained by the micelles being not perfectly spherical. To explain the remaining difference, it is assumed that the micelles are hairy, i.e. they have molecular chains protruding into the milk serum. The hairyness would increase with decreasing temperature and be largely removed by the action of rennet. It would cause some entropic repulsion between micelles at close approach.
A new laboratory method for preventing bacteriophage attack on cheese starter streptococci
Authors: Erskine J. M. 
Published: June 2009

SummaryA method of preventing the action of bacteriophages on starters in cheese milk is described. Direct intramuscular injection of high titre phage preparation into a cow resulted in the appearance in the blood serum and milk of a high concentration of antibody. Even after considerable dilution this antibody is capable of neutralizing the homologous phage and serologically related phages. Methods of concentrating the antibody-containing milk were examined with a view to commercial application of the method in the protection of starter bacteria from phage attack.
Some bound forms of pantothenic acid in the milk of normal dairy cows
Authors: Hibbitt K. G. 
Published: June 2009

SummaryThe levels of coenzyme A were measured in the milk of normal dairy cows during the first 20 weeks of lactation. Estimations were made on milk samples obtained from some cows in their first lactation and from older cows. The microbiological method described by Brown (1959) for the estimation of bound forms of pantothenic acid was used, but considerable modification of this method was necessary to avoid elevated results due to the stimulatory action of free pantothenic acid on the response of the assay organism. Appreciable amounts of coenzyme A were excreted in the milk of cows in their second or subsequent lactations during the first 12–16 weeks after parturition, peak levels being reached after the end of the 1st week. In comparison, only small amounts of coenzyme A were excreted in the milk of cows in their first lactation. Attempts to detect the presence of phosphopantetheine in milk were unsuccessful.
A new method for the preparation of an immunologically homogeneous β-casein
Authors: Garnier J. , Ribadeau-Dumas B. , Mocquot G. 
Published: June 2009

SummaryThe preparation of an immunologically homogeneous β-casein is described, involving several separations by chromatography on diethylaminoethyl cellulose with urea-imidazole buffer at pH 7, followed by Tris buffer at pH 8·2. 30% of the β-casein present in the skim-milk is obtained by this method. β-casein gives a single band in urea-starch gel electrophoresis when it is obtained from the milk of cows homozygous for this character.
Teneur en caséine κ de la caséine de colostrum de vache
Authors: Ribadeau-Dumas B. , Veaux Monique 
Published: June 2009

SummaryCasein derived from cow's colostrum contains 0·85%N-acetyl neuraminic acid and liberates 2·95% nitrogen soluble in 12% trichloroacetic acid (NPN) under the action of rennin. It therefore appears to contain a large proportion of κ-casein (calculated to be approximately 35%).The smaller the micelles of casein in colostrum the larger is the amount ofN-acetyl neuraminic acid they contain. Soluble casein, i.e. 25% of the casein in colostrum, contains 1·52% of this acid and gives 6·24% NPN under the action of rennin.Casein and particularly the soluble casein of colostrum appear to be important sources of κ-casein and caseino-glycopeptide.
Factors affecting the multiplication and survival of coagulase positive staphylococci in Cheddar cheese
Authors: Reiter B. , Fewins B. Gillian , Fryer T. F. , Sharpe M. Elisabeth 
Published: June 2009

SummaryThe presence of a thermolabile inhibitor of coagulase-positive staphylococci in milk was confirmed. Starter streptococci significantly suppressed the multiplication of staphylococci in milk not only by their acid production but also by some other competitive effect.Cheesemaking trials showed that staphylococci multiplied considerably more rapidly in ‘slow’ or ‘sweet’ cheese, where the starter was inhibited by phage, than in normal cheese. Little decrease in numbers occurred in ‘sweet’ cheese even after 18 months, in contrast to the rapid decline in the normal cheese.Staphylococci subjected in the laboratory to sublethal heat treatments had a prolonged lag phase on all media and their % recovery on selective media was significantly lower than on optimal non-selective media. It is suggested that the low survival rate of the staphylococci in cheese made from milks heated at sublethal temperatures is due to the lag in recovery of heat-shocked cells and their inability to multiply in the unfavourable cheese curd.
A comparison of media for counting and isolating the bacteria from Cheddar cheese
Authors: Robertson P. S. 
Published: June 2009

SummaryIn an endeavour to find an ideal medium for the isolation of the bacteria from Cheddar cheese 10 media were compared. The initial criterion was of ability to yield maximal counts with each of 23 representatives of species common in Cheddar cheese. Subsequently the more promising media were compared for ability to give the highest counts for cheese emulsions without obvious distortion of the proportions of the various species present.Since no one medium gave maximal counts with all strains, two complementary media of quite different composition are suggested for the bacteriological examination of cheese.
Studies on the к-casein complex: II. The isolation of a sialic acid-containing fraction by disrupting the complex at low pH in the presence of sodium chloride
Authors: Beeby R. 
Published: June 2009

SummaryWhen crude к-casein was precipitated at pH 3 in the presence of 0·4m-NaCl the supernatant contained up to 80% of the total sialic acid but no detectable cystine or cysteine. Two fractions were obtained from this supernatant by chromatography on DEAE cellulose; one containing 4–6% sialic acid and the other only onetenth of this amount.Most of the sialic acid of the sialic acid-rich fraction was soluble in 12% trichloracetic acid following treatment with rennin. It is suggested that the glycopeptide released by the action of the enzyme on casein originates from this fraction.
A method of maintaining a reference flora of constant bacteriological composition
Authors: Reiter B. , Fryer T. F. , Sharpe M. Elisabeth 
Published: June 2009

SummaryA method is described by which the microbial flora of a raw milk sample was reconstituted on different occasions. After segregation on selective media into groups consisting of lactic acid bacteria, Gram-negative rods including coli-aerogenes, staphylococci, streptococci, and microbacteria, and propagation by replica plate techniques on optimal media, suspensions of these groups of organisms were then added in approximately the original proportions to 40 gal batches of heated milk of low bacterial count. When this was repeated on 18 different occasions over a period of 11 weeks, the milk flora was found to be almost identical with the original one.
The effect of inoculating the bovine teat duct with small numbers of Staphylococcus aureus
Authors: Newbould F. H. S. , Neave F. K. 
Published: June 2009

SummaryFifty-seven inoculations of a strain of Staphylococcus aureus were made into the outer 4 mm of the teat ducts of 8 cows. The inocula ranged from 10 to 600 colony-forming units (CFU) and were made with a stainless steel instrument designed to overcome the disadvantages of glass rods and cotton swabs hitherto used.A single inoculation resulted in either no colonization of the duct, in temporary colonization for up to 7 days, or in colonization followed by intramammary infection.The recovery of the organisms depended on the size of the inoculum. When 70–100 CFU were placed in the teat duct no organisms were recovered from 12 of 24 quarters after the 1st post-inoculation milking. When 500–600 CFU were used, organisms were recovered from all of 31 quarters for at least 3 milkings, and from 61% for 6 milkings or more, in spite of dipping the teats in a strong disinfectant twice daily.Intramammary infection developed in 1 of 12 quarters (8%) inoculated in the teat duct with about 600 CFU when the animals were milked twice daily, and in 5 of 19 (23%) quarters if the 1st post-inoculation milking was omitted.There was no evidence of sensitization resulting from previous infection.
A survey of the incidence of coagulase-positive staphylococci in market milk and cheese in England and Wales
Authors: Sharpe M. Elisabeth , Fewins B. Gillian , Reiter B. , Cuthbert W. A. 
Published: June 2009

SummaryThe occurrence of coagulase-positive staphylococci in 954 samples of raw or heat-treated market milk and in 910 samples of cheese of different varieties, taken at 40 cheese factories or farms in England and Wales was determined. Only 9% of the cheeses contained more than 500 000 staphylococci/g, and these were all made from raw milk. All but the mildest of the heat treatments used were effective in greatly reducing the numbers of staphylococci present in milk and usually resulted in cheese virtually free from staphylococci. The effect of sublethal heat treatment on multiplication of these organisms in cheese curd is discussed.
A simple laboratory-scale HTST milk pasteurizer
Authors: Franklin J. G. 
Published: June 2009

SummaryA simple, quick, batch-type method for the laboratory-scale HTST pasteurization of milk is described and details of construction, operation, cleaning and sterilization of the apparatus are given. The heating and cooling curves approximate closely to those of commercial HTST milk-pasteurizing plants and the end-product, as measured by residual phosphatase, is similar. The method has a relatively high sample throughput and is suitable for the routine pasteurization of large numbers of milk samples of up to 300 ml in volume. Other possible applications of the method are discussed.
The detection of abnormal milk by electrical means
Authors: Greatrix G. R. , Quayle J. C. , Coombe R. A. 
Published: June 2009

SummaryA preliminary study has been made of some relationships between the relative conductivity of milk and its cellular content and 3 basic relationships subjected to an extensive computer analysis. The results suggest that relative conductivity can be used to detect about 3 out of every 4 cows yielding milk samples from one or more quarters with a cellular content greater than 500000/ml, and about 4 out of every 5 cows with a cellular content greater than 1000000/ml. Less than 1 in 20 cows would be incorrectly detected as having cell counts greater than 500000/ml in milk from any one quarter.
The effects of a series of 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 isocaloric replacement of part of the dietary concentrate mixture by 5% lauric acid (99% pure) or by 10% of myristic (95% pure), palmitic (96% pure) or stearic (94% pure) on the yield and composition of milk fat was investigated in 2 feeding experiments with a total of 10 cows in mid-lactation. The concentrate mixtures were given with a high-roughage diet that supplied 9·1 or 7·7 kg hay/day in expts 1 and 2, respectively.In expt 1 the inclusion of myristic acid in the diet decreased the yields of milk and solids-not-fat (SNF), but increased the percentage of fat in the milk without altering the fat yield. When stearic or palmitic acid was included in the diet there was an increase in milk fat yield; palmitic acid caused the greater increase. In expt 2 the inclusion of lauric acid in the diet did not appear to affect the yields of milk or SNF but it caused large reductions in the percentage of fat in the milk and in the yield of fat.In expt 1 the inclusion of myristic acid increased the yields and percentages of 14:0, 14:1 and 16:1 in the milk fat and decreased the yields and percentages of the short-chain fatty acids (4:0–8:0), 16:0, 18:0 and 18:1. When palmitic acid was included in the diet there were increases in the yields and percentages of 16:0 and 16:1 in the milk fat and decreases in the yields and percentages of 10:0, 12:0, 14:0, 18:0 and 18:1. The inclusion of stearic acid in the diet increased the yields and percentages of 18:0 and 18:1 in the milk fat and decreased the yields and percentages of 12:0 and 16:0. In expt 2 the inclusion of lauric acid in the diet increased the yield and percentage of 12:0, and in 1 cow the content of 14:0 in the milk fat; there were reductions in the yields and percentages of all the other fatty acids in the milk fat. There was no evidence of any marked elongation of the carbon chains of 12:0 and 14:0 in the mammary gland to form 16:0 or 18:0.In expt 1 the incorporation of myristic acid in the diet decreased the concentration of total steam-volatile fatty acids in rumen liquor. The inclusion of either myristic, palmitic or stearic acid in the diet had little effect on the relative proportions of the individual volatile acids in the rumen liquor. In expt 2 the addition of lauric acid to the diet reduced the acetic acid:propionic acid ratio in the rumen liquor.
Chemical methods for assessing lipid oxidation in ultra-high-temperature creams
Authors: Downey W. K. 
Published: June 2009

SummaryThe flavour quality and stability of 3 different UHT creams are described. The rate of oxidation was measured by the thiobarbituric acid (TBA) and peroxide methods as well as by organoleptic assessment. Lipid oxidation developed in some UHT creams on prolonged storage, particularly in creams manufactured during the winter months and stored at 18°C, while little or no oxidation occurred at 4 °C. Creams manufactured during the summer months were most resistant to oxidation. Creams with no detectable oxidized flavour had TBA values ≤ 0·08; values ≥ 0·16 and peroxide ≥ 2·0 were associated with pronounced oxidized flavour. These relationships between the chemical and organoleptic assessments were highly significant (P < 0·01). Low peroxide levels (< 2·0) were not necessarily indicative of good flavour quality.
A method for the quantitative analysis of the enzyme complement of commercial rennets
Authors: O'Leary P. A. , Fox P. F. 
Published: June 2009

SummaryA method by which it is possible to quantify with very high accuracy the levels of rennin, bovine pepsin, porcine pepsin and proteases from Mucor miehei (fromase) or M. pusillus (emporase) in a ‘commercial rennet’ containing some or all of these enzymes is described. The method employs chromatography on DEAE cellulose in piperazine buffer (0·02M, pH 5·3) to fractionate the enzymes into 2 groups: (peak A) rennin, emporase, and fromase, eluted at ∼0·2 m-NaCl and (peak B) bovine and porcine pepsins eluted at ∼0·4 m-NaCl. The rennin in peak A is selectively denatured at pH 9·0, 20°C for 60 min and the rennin plus emporase at pH 6·0, 60°C for 20 min, permitting the quantification of emporase and fromase (and rennin by difference) and fromase, respectively. The porcine pepsin content of peak B is quantified by selective denaturation at pH 7·0, 30°C for 3 min. A number of commercial rennet preparations were analysed using this method: full rennet contained 45–60% bovine pepsin and ‘half and half’ contained 20–25% rennin, 25–30% bovine pepsin and 50% porcine pepsin.
Properties of aseptically packed ultra-heat-treated milk: Electron microscopic examination of changes occurring during storage
Authors: Andrews A. T. , Brooker B. E. , Hobbs D. G. 
Published: June 2009

SummaryChanges in the appearance of casein micelles and fat globules in ultra-heat-treated (UHT) milk were comparatively slight within a 14-month storage period although closer inspection often revealed the beginnings of some of the changes observed after even longer storage. Within this period the milks remained liquid and no evidence for any proteolytic breakdown was seen on electrophoretio examination. After 34 months the milks had all gelled and there was evidence of a small amount of proteolytic breakdown. Electron microscopic changes were striking and depended on storage temperature. At 4 °C the casein micelles in the gel phase had become very ‘spiky’ and long tendrils often bridged micelles, forming extensive networks. At room temperature and at 30 °C this tendril formation was less marked and the average micelle size was considerably greater than in freshly processed milk. There was also clear evidence for the coalescence of micelles. After storage at 37 °C the micelles were much larger than in the other samples, often exceeding 0·4 mμ in diam.
Hydrolysis of lactose in milk and whey with minute amounts of lactase
Authors: Dahlqvist A. , Asp N.-G. , Burvall A. , Rausing H. 
Published: June 2009

SummaryA method for lactose hydrolysis in sterile milk or whey with Saccharomyces lactis lactase is described. The properties and stability of this enzyme are very favourable for use in milk and neutral whey. The long shelf life of sterilized milk and whey products is utilized for a prolonged incubation time – one to several weeks – at room temperature. Thus, minimal amounts of enzyme are needed which makes enzyme costs very low.
Nutritional value of lactose-hydrolysed milk: protein quality after some industrial processes
Authors: Burvall A. , Asp N.-G. , Dahlqvist A. , Öste R. 
Published: June 2009

SummaryThe nutritional protein quality of lactose-hydrolysed milk after some industrial processes was studied with N balance experiments on growing rats.Ultra-high-temperature sterilization and evaporation at 25 °C did not influence the nutritional value significantly, whereas spray-drying under conditions usually used for ordinary milk gave a considerable reduction in protein quality. This was caused mainly or entirely by loss of biologically availabe lysine.
Some factors involved in milk lipase activation by agitation
Authors: Deeth H. C. , Fitz-Gerald C. H. 
Published: June 2009

SummarySeveral factors which influence the shape of activation curves relating the degree of agitation-induced lipolysis in raw milk to the temperature of agitation were investigated. Curves of the type previously reported (Fitz-Gerald, 1974) containing a maximum at 12–15 °C resulted from low speed agitation with incorporation of air, with fresh (< 12-h old) milk, with milk of fat content ≥ 3·0 % approx. and by low temperature incubation of activated milks. Activation curves containing no distinct maximum at 12–15 °C were obtained from high speed agitation and homogenization, with milks of low fat contents and with aged (≥ 24-h old) milk. Agitation at low temperatures resulted in a maximum degree of activation in fresh milk after 2–4 h cold storage.During agitation of raw milk redistribution of lipase activity between the cream and skim-milk phases occurred. The extent of redistribution depended on the time and temperature of agitation. Cream prepared from milk agitated at low temperatures contained lipase activity several times greater than cream from unactivated milk. The practical significance of this effect is discussed.