bluuebunny/crossref_metadata_2025 huggingface dataset:
225. The casein number for diagnosis of mastitis. II. The effect of advanced lactation, and of storage and preservation of the milk sample
Authors: Rowland S. J. , Zein-El-Dine M.
Published: June 2009

1. An investigation was made of the effect on the casein number of (a) advanced lactation, (b) storage of the milk sample at room temperature and in the refrigerator, and (c) storage of the sample at room temperature after the addition of the following preservatives: potassium dichromate, mercuric chloride, formaldehyde, crystal violet and sodium azide.

2. The casein number method of mastitis diagnosis is not applicable to cows in advanced lactation. It did not distinguish between infected and uninfected quarters, as all quarters in the drying-off stage produced milk with a number below normal. At the end of lactation the mean casein, soluble protein plus non-protein, and total nitrogen contents were 21, 86, and 36% greater respectively than when the cows were in full milk.

3. There was a decrease in the casein number of the milk samples on keeping at 16–18° C. or with preservatives owing to the hydrolysis of casein to proteose-peptone and non-protein nitrogenous substances. For the diagnosis of mastitis from the casein number, samples should not be kept at room temperature for more than a few hours before analysis. Keeping at 0–2° C, and at room temperature with the addition of 0·2, 0·05, and 0·01 g. potassium dichromate, formalin or mercuric chloride respectively per 100 ml. of milk, prevented significant reduction of the casein number for 24–48 hr.
246. A long-term study of the partition of serum calcium in Ayrshire cows
Authors: Godden W. , Duckworth J.
Published: June 2009

The following average fractionation of serum calcium in the dairy cow has been reported:
274. Preliminary experiments on the vapour pressure of dairy products
Authors: Blair G. W. Scott , Dix F. J. , Wagstaff A.
Published: June 2009

1. Methods for measuring the vapour pressure of cheese and milk are discussed, and vapour pressure/moisture curves are given for a number of different varieties of cheese. The progressive artificial damping and drying of cheese produces no appreciable hysteresis in these curves.

2. The vapour pressure curve is much influenced by the amount of salt in the cheese, but differences between varieties cannot be accounted for entirely in terms of differences in NaCl content.

3. A preliminary experiment on the relationship between vapour pressure of Stilton cheese and amount of blueing indicated that such a relationship does in fact exist but that a much larger experiment is required before the connexion is fully understood.

4. Preliminary experiments on the measurement of the vapour pressure of milk, although interrupted at rather an early stage, showed that, even so, additions of 2–3% of water in milk can be satisfactorily detected.
277. Vitamin A and C in cow's milk, with a note on the synthesis of vitamin C in bovines
Authors: Ray S. N. , Chand Karam , Rau K. Govind
Published: June 2009

1. A simple method is described for the determination of carotene and vitamin A in milk. Figures for the carotene content of milk were higher and those for vitamin A were lower than similar figures reported by Western workers.

2. Figures for vitamin C in milk are similar to corresponding figures of English and American workers. Previous low values for vitamin C, reported by Indian workers, are due to destruction of the vitamin by light.

3. The vitamin C concentration of milk is not subject to great individual variation, probably because cows cannot excrete in milk any vitamin C taken in with the food and because vitamin C of milk is produced by synthesis within the mammary glands from some simple blood constituents.

4. To test the ability of bovines to synthesize vitamin C, young calves were kept for long periods on a strictly vitamin C-free diet. The concentration of vitamin in the blood and other tissues of these animals remained, however, at a normal level. Calves appear therefore to be able to synthesize sufficient vitamin C for their normal growth and activity.

5. Unsuccessful attempts were made to produce vitamin C in vitro by growing bacteria isolated from various parts of the alimentary canal on media prepared from ingesta taken from the regions from which they were isolated.
281. Volatile acids of cheese: III. Application of the extraction method
Authors: Hiscox E. R. , Harrison J. , Wolf J. Z.
Published: June 2009

1.Details are given of the extraction method for the estimation of the volatile acids in cheese, as used in the study of some white and blue-veined varieties.

2. On the basis of the distribution of valatile acids, hydrogen-ion concentration and nitrogen breakdown, distinctions could be drawn not only between the white and blue-veined varieties as a whole, but also between the Roquefort and Stilton groups of the latter varieties.

3. A high total quantity and a characteristic distribution of the volatile acids appeared to be related to the heavy pricking of cheese of the Roquefort group.
283. The keeping qualities of milk powders: Part I. Addition of antioxidants
Authors: Waite R.
Published: June 2009

1. Hydroquinone is an effective antioxidant for the butter-fat of spray-dried whole-milk powder, but in a concentration equivalent to 0·5% of the weight of fat (0·12% on the weight of powder) it produces an objectionable ‘metallic’ flavour in the powder and reconstituted milk.

2. Oat flour is much less efficient than hydroquinone as an antioxidant but 0·25% added to the milk, preferably before condensing, increases the resistance of the resultant powder to the development of tallowiness by the equivalent of about 4 months at normal temperatures. Raising the concentration of oat flour to 0·5% approximately doubles this increase but at the same time imparts a noticeable oat flavour to the powder.
311. The influence of bacteriophage on the cheese-making process
Authors: Hunter G. J. E.
Published: June 2009

The presence, in the cheese milk, of phage active against the organisms of the ‘singlestrain ’ culture in use as starter leads to its multiplication during the cheese-making process. The extent to which the presence of phage is made evident in the vat depends largely upon the amount of initial infection. A heavy infection permits sufficient multiplication of the phage to cause lysis of the organisms and consequent cessation of acid development before the manufacturing process is completed. A light infection may have no noticeable influence upon the performance of the starter in the vat. Intermediate amounts have an effect on the rate of acid development in the later stages of the process, but within certain limits there is little adverse influence on the quality of the cheese produced.
340. Variations in the demand for milk and cream among four social classes of consumers in the city of Leeds
Authors: Bransby E. R.
Published: June 2009

The general experience of the retail milk trade is that considerable variations exist in the demand for milk and cream at different times of the year, and that these need careful consideration to preserve the proper balance between the supply of, and demand for milk. Different social classes of consumers are also known to exhibit different habits of milk and cream consumption. This paper examines the fluctuations of demand for milk and cream over a 1-year period of four social classes of consumers.
360. Reactions to hot atmospheres of Jersey cows in milk
Authors: Riek R. F. , Lee Douglas H. K.
Published: June 2009

Four grade Jersey cows were exposed for 7 hr. twice a week to each of several atmospheres having dry-bulb temperatures ranging from 85 to 110° F. and absolute humidities ranging from 6 to 16 gr./cu.ft. The following reactions were studied: rectal temperature; pulse rate; respiratory rate; respiratory volume; evaporative loss; calcium, phosphate and erythro-cyte composition of the blood; milk volume and butterfat content; behaviour.

Rectal temperature rose to higher values with less ready establishment of equilibrium the hotter the condition, but exceeded 107° F. only in the hottest atmosphere. (Dry-bulb temperature 110° F., absolute humidity 16 gr./cu.ft.)

Respiratory rate was similarly and markedly affected. In both cases, humidity had a marked effect as well as temperature, an increment of 0–4 gr./cu.ft. (approx. 4%) in humidity having the same effect as 1° F. rise in air temperature. The highest average respiratory rate was 200/min. Respiratory minute volume rose less than the rate, so that tidal volume was reduced.

Pulse rate was essentially unaffected by a rise in temperature but tended to rise somewhat with humidity.

Evaporative loss was markedly increased by temperature, much less so by humidity. Increased pulmonary ventilation was inadequate to account for the observed losses, which are attributed to sweat-gland activity.

Behavioural changes included some licking, panting, salivation, mild agitation, cessation of rumination and refusal of water. Weakness and staggers did not occur under these conditions.

Neither milk nor butterfat production was essentially affected by the exposures. Blood calcium and phosphate levels fell, but the erythrocyte count was unchanged.

These findings provide basic data with which subsequent observations under varying conditions can be compared.
365. The bacteriological quality of british spray-dried milk powder
Authors: Higginbottom Constance
Published: June 2009

The increased use of dried-milk products in human feeding during recent years stimulated investigations into and more rigid control of the bacteriological quality.

Spray-dried milk powder from the same eight British plants has been examined for bacteriological quality at this Institute in several different years and the results show the marked improvements which have been made.
373. Inhibitory strains of lactic streptococci and their significance in the selection of cultures for starter
Authors: Hoyle Margery , Nichols Agnes A.
Published: June 2009

1. Inhibitory strains of lactic streptococci have been encountered amongst strains of Str. cremoris isolated from starter and amongst strains of Str. lactis, isolated from sour milk, which had otherwise been regarded as suitable for cheesemaking.

2. Methods are described for determining the concentration of inhibitory substance produced and the effect of these inhibitory strains on a wide selection of lactic streptococci.

3. The significance of the presence of strains of lactic streptococci having inhibitory properties, if incorporated in starters, particularly when the strains are prepared separately and mixed in the vat, is discussed. Recommendations for the exclusion of inhibitory strains from such starter mixtures are made.
387. Bacteriophage in typing lactic streptococci
Authors: Nichols Agnes A. , Hoyle Margery
Published: June 2009

1. The present position in the problem of ‘slow’ starter due to phage lysis has been reviewed.

2. The sources of some 450 strains of lactic streptococci, collected from a wide field, are given. The methods used in their selection for use as starter together with storage conditions, suitable to maintain their activity, have been discussed.

3. The sources from which phages for the lactic streptococci have been obtained and the methods of ‘building up’ a phage of high titre from dairy products, have been discussed. Attempts have been made to isolate phages from pig-faeces, after feeding starter strains to pigs, to adapt phages to strains previously unattacked and to establish interrelationship of the phages and strains of lactic streptococci with phages and strains of enterococci.

4. The strains of lactic streptococci have been classified in eleven phage types by modifying a method described for the phage typing of staphylococci. Identification of a type has been based on the reactions of a ‘phage pattern’ and not on the reaction of a single phage. It has not been possible to adapt one phage to lyse all the strains of one type and to replace the several phages on which type identification originally depended but, adapted phages have indicated the subdivision of some types.

5. The application of the ‘phage-resistant carrier’ strain phenomenon to phage typing has been investigated. The results have helped in the typing of some strains.

6. Phages used in typing the strains have been classified by means of antiphage sera, prepared from a selection of the test phages. On the data presented the majority of the phages were divided into three groups and the results have been discussed with reference to the phage types suggested.

7. The significance of phage typing, adaptation of phage and phage carrying in the selection of starter strains has been considered and the best method of applying this information to the control of ‘slowness’ in cheese factories has been discussed.
390. The estimation of losses of butterfat in churning
Authors: McDowall F. H. , McDowell A. K. R.
Published: June 2009

The Bird & Derby method of calculating percentage butterfat loss in buttermilk is in error because it assumes that all the buttermilk in the granules at draining is retained in the buttermilk, whereas much of it is washed out in the wash water. Lactose estimations in butter and buttermilk confirm Udy's finding that butter contains about 10% of buttermilk. The Udy formula, viz.

is therefore in this respect correctly based and can be applied to individual churnings of butter in the same way as the Bird & Derby formula has been applied. The Bird & Derby formula should be discarded except for use when the granules are not washed with chill-water.

Both the Udy and the Bird & Derby formulae do not allow for the content of fat in the buttermilk retained in the butter or for the influence of fat content of the buttermilk on the calculated quantity of serum lost. When these factors are taken into account the Udy formula becomes

The correction +0·0012f F is not significant.
Device for preparing roll-tube cultures
Authors: Moir G. M. , Thomson G. I.
Published: June 2009

The roll-tube method for estimating bacterial counts was devised by Esmarch(1), but was soon afterwards superseded by the introduction of Petri plates which have several advantages for cultural and counting purposes. The roll-tube method, however, has been revived by several workers (2,3,4), and where a simple, rapid and economical method is required it is very useful, especially if low counts are being dealt with. For this reason it is particularly suitable for yeast and mould counts in butter and has been so used in this laboratory for many years. In addition to its regular use for this purpose, several series of comparisons have shown that the roll-tube method is capable of giving results which compare very well with Petri plate counts upon milk, using the usual dilution technique in both cases.
428. The acid phosphatase of mammary tissue of the cow and the rat
Authors: Mullen J. E. C.
Published: June 2009

1. Mammary tissue of the cow and the rat contains acid phosphatase. The respective pH optima are 5·5–5·8 and 6·0.

2. The enzyme in cow mammary tissue is probably one of type AII in the Folley & Kay (10) classification.

3. The acid phosphatase of cow mammary tissue is inhibited by a factor in raw cows' milk. This factor is destroyed by heat.

4. On the basis of rate of hydrolysis of phenylphosphate at the optimum pH there is about 5 times more alkaline phosphatase in the mammary tissue of the cow than acid phosphatase.

5. The effect of adrenalectomy and replacement therapy through the administration of cortical steroids has no marked effect on the acid phosphatase of rat mammary tissue.
458. Clinical mastitis in six herds freed from Streptococcus agalactiae
Authors: Neave F. K. , Phillips Mary , Mattick A. T. R.
Published: June 2009

The difficulty of keeping herds free from Strep. agalactiae for long periods has been demonstrated in five herds. In one sense, however, these herds were not representative of the majority of herds for they were relatively large and under the same management. Furthermore, if one herd became infected with the streptococcus, there was a real risk of the infection spreading to all herds via the hands of the relief milker, particularly if hand stripping was practised and no special precautions were taken by the relief milker.

There is no doubt that herds under the same management should take stringent precautions against the spread of infection between herds.
473. The serological classification ofStreptococcus cremoris
Authors: Briggs C. A. E. , Newland L. G. M.
Published: June 2009

1. Attempts to produce in rabbits group N sera forStreptococcus cremoris, using suspensions of living, disintegrated and heat-treated bacterial cells, yielded only non-specific products, cross-reactions occurring most commonly and intensively with HCl extracts of the streptococci of groups K and L.

2. The non-specific antibodies in these sera were completely removed by absorption with streptococci of group K or L, the group N reactions being only partially impaired.

3. In order to inactivate, before immunizing rabbits, that antigen in the ‘cremoris’ cells responsible for stimulating the production of non-specific antibodies, the organisms were ‘absorbed’ with an excess of group K or L antiserum.

4. With suspensions of organisms treated in this way, potent group N specific precipitating sera were obtained for both freshly isolated and freeze-dried strains ofStr. cremoris.

5. The identity ofStr. cremoriswith serological group N is thus established.
479. Studies on the biological value of the proteins (nitrogen) of dried skim milk: effects of the addition of certain amino-acids, of age of rat and of level of protein intake
Authors: Henry K. M. , Kon S. K.
Published: June 2009

1. It has been shown that the biological value of undeteriorated dried skim milk is depressed to the same extent by the addition of 1·25% L-lysine as by the addition of 1·25% D-lysine. The latter is not used by the rat. It is therefore concluded that the added L-lysine is surplus to the animal's needs and that the apparent lowering of the biological value is due to excretion of the lysine in the urine.

2. The slightly greater loss in the biological value of milk stored in air-pack compared with gas-pack was eliminated by the addition of 0·5% L-histidine to the former. Histidine is not a limiting amino-acid in the control or stored gas-pack milks for either young or adult rats.

3. A lower biological value was found for the control milk with adult than with young rats at 4 and 8% levels of intake. No further lowering in the biological value of the stored milk, deficient in lysine, was observed with adult rats, the value obtained for this milk being independent of the age of the rat. These results are in keeping with the known lowered requirements of the adult rat for lysine.

4. The significance of these findings in relation to the known amino-acid requirements of young and adult rats is discussed.
480. The role of micro-organisms in dye-reduction and keeping-quality tests: II. The effect of micro-organisms when added to milk in pure and mixed culture
Authors: Garvie Ellen I. , Rowlands A.
Published: June 2009

1. A study of the ability of pure cultures to reduce methylene blue and resazurin at 37·5° C., to reduce methylene blue at 22° C. and to cause milk spoilage as measured by precipitation with 68 % alcohol, and the clot-on-boiling test has revealed marked differences in behaviour between cultures.

2. At 37·5° C., with the exception of two cultures, there was good agreement between the time of reduction of methylene blue and resazurin. The two exceptions were a group BStreptococcuswhich reduced methylene blue but failed to reduce resazurin during the 9 hr. period of observation and an unclassifiedStreptococcusgrowing at 45° C. which reduced resazurin before methylene blue; the latter dye was found to retard the multiplication of the culture slightly.
481. Simple and rapid methods for the estimation of bacterial phosphatases using di-sodium p–nitrophenylphosphate as substrate
Authors: Tramer J.
Published: June 2009

Bacterial phosphatases of growing organisms can be simply demonstrated by incorporating di–sodium–p–nitrophenylphosphate (pNPP) into suitable media. The phosphatase content of a bacterial suspension can be assessed by incubating a measured amount of it with unbuffered or suitably buffered pNPP solutions. The yellow colour (in alkaline solution) of p-nitrophenol liberated from the substrate by phosphatase can be measured accurately and conveniently in a photoelectric absorptiometer, or estimated in a Lovibond comparator using permanent colour standards. The usefulness of the tests for differentiating between members of certain genera is demonstrated by the reactions of Bact. aerogenes and Bact. cloacae, for which a close relationship between phosphatase production and gelatine liquefaction times has been found. The optimal conditions for hydrolysis of pNPP by the phosphatase of a strain of Bact. aerogenes have been established.
482. ‘Wild’ strains ofStreptococcus cremoris
Authors: Hirsch A.
Published: June 2009

Of thirty-five strains of streptococci isolated from milk produced in the Jura mountains, two were strains ofStreptococcus cremoris. It appears, therefore, that this organism occurs in the wild state.
488. An improved method of observing the clotting of milk containing rennin
Authors: Berridge N. J.
Published: June 2009

The method of assaying rennin described by Berridge(1) requires the formation under reproducible conditions of a thin flowing film of milk. Although the skill needed to keep the film flowing at the optimum rate as the clotting point is approached is readily acquired, an automatic method has the advantage of complete reproducibility. A suitable film can be maintained if 10 ml. of milk are placed in a boiling tube of 2·2 cm. internal diameter and the tube, with its axis inclined at about 30° to the horizontal, rotated at 3·0 r.p.m. In the apparatus now used, the boiling tube is mounted on a rubber bung, which in turn is mounted concentrically on a spindle connected through Meccano gears to a 'Sangamo' electric clock motor. A special mechanical coupling allows the bung to be rotated by hand one revolution forwards, thus allowing 20 sec. for fitting or releasing the boiling tube before the drive is again taken up.
501. The effect of storage at different relative humidities on the survival of micro-organisms in milk powder and in pure cultures dried in milk
Authors: Higginbottom Constance
Published: June 2009

1. Two spray-dried milks, one separated and one whole milk, have been stored at 25°C. for 48 and 103 weeks respectively at relative humidities ranging from 0 to 100%. At high humidities (80–100% r.h.) a rapid fall in the numbers of bacteria was followed by rapid growth of bacteria and by overgrowth by moulds. At relative humidities below 80% the number of surviving bacteria increased with decreasing humidity to maximum survival at about 10% r.h. and then tended to fall again towards 0% r.h.

2. The changes in the distribution of the different types of bacteria in the dried milks at different relative-humidities are discussed.

3. Maximum survival at 5–15% r.h. has been confirmed with pure cultures (dried in milk) of a Streptococcus and a Micrococcus originally isolated from dried milks.

4. The marked loss of viability of bacterial spores noted in dried milks stored over P2O5 or concentrated H2SO4 has been confirmed for a dried suspension of the spores of a typical strain of Bacillus subtilis.
503. The properties of New Zealand butters and butterfats: III. Seasonal variations in the nature of the unsaturated acids of butterfat as estimated by spectrophotometric methods
Authors: McDowell A. K. R.
Published: June 2009

Variations in the unsaturated acid constituents of butterfat samples from the Manawatu district of the North Island of New Zealand over the months October to April were studied by the spectrophotometric technique, applied both before and after alkali isomerization of the fat.

The seasonal variations in the iodine values of the butterfats were found to be closely related to the changes in oleic acid content. Conjugated dienoic acids, though present in relatively small amounts, showed a somewhat similar seasonal trend in values to oleic acid. The results for percentage content of non-conjugated dienoic acids were low, and they fluctuated considerably from month to month. Conjugated trienoic and tetraenoic acids were absent or present only in traces. Small but fairly consistent quantities of nonconjugated trienoic and tetraenoic acids were found in all samples.
507. Variations in the fat content of milk throughout the milking process
Authors: Whittlestone W. G.
Published: June 2009

The various theories commonly used to explain the increasing fat content of cow's milk with stage of milking are examined and found inadequate. It is suggested that the trends in fat content as a cow is being milked may be explained by the clustering of the fat globules and the consequent partial filtering out of the clusters as the milk flows from the gland. Evidence for clustering of fat in cow's milk at body temperature is presented and the application of the theory to the sow discussed.
512. A photoelectric method for determination of fat aldehyde values
Authors: Dolby R. M.
Published: June 2009

In the determination of aldehyde values of slightly oxidized butterfat samples by Schibsted's method, the colour of the butterfat prevents accurate matching with the colour standard. Interference by butterfat colour is eliminated, and more accurate results are obtained if the colour is measured in a photoelectric colorimeter at a wavelength of 510 mµ. A small constant correction for the absorption by butterfat at this wave-length may be made.
517. Reactivation of milk phosphatase following heat treatment. II
Authors: Wright R. C. , Tramer J.
Published: June 2009

1. Using the capillary technique previously described, examination has been made of various factors in relation to the reactivation of raw milk phosphatase. Of these, ageing of the raw milk was found to affect considerably the level of reactivation, this increasing as the bacteriological quality of the milk deteriorated.

2. It has been found that absence of air and the presence of reducing conditions in the raw milk increases the reactivation obtained.

3. The influence of reducing conditions on the reactivation of a bacterial phosphatase has been demonstrated.
548. Intramammary pressure changes in the lactating sow: II. The effects of vasopressin and acetylcholine
Authors: Whittlestone W. G.
Published: June 2009

Measurements of intramammary pressure changes in the sow following intravenous injection have shown that the milk-ejecting action of vasopressin and acetylcholine is similar to that of oxytocin. Doses up to 0·4 mg. of histamine produced no measurable effects within the mammary gland.
568. The rate of secretion of milk and fat
Authors: Bailey G. L. , Clough P. A. , Dodd F. H.
Published: June 2009

1. The effects of variations in the length of the milking interval and of the preceding milking interval were measured for five cows.

2. The yield of milk increased with the lengths and decreased with the square of the lengths of the milking interval and of the previous milking interval.

3. The yield of fat increased with the length of the milking interval and the length of the preceding milking interval and decreased with the square of the length of the milking interval.

4. The biological implications of each of the mathematical terms are discussed.

5. The effect of the preceding interval was through a direct carry-over of residual milk and also by an effect on the metabolic rate of the alveoli throughout the following interval.

6. The rate of secretion of both milk and fat declined with increasing milking interval; there was evidence that the rate of decline for the milk was greater than that for the fat, for the fat percentage of the milk tended to increase.
583. The effect of steam, hypochlorite and caustic soda used for treating direct-to-can milking equipment, on the bacteriological quality and flora of milk
Authors: Carreira D. F. C. , Clegg L. F. L. , Clough P. A. , Thiel C. C. , Akam D. N. , Gruber Marie , Hirons Elizabeth
Published: June 2009

Two farms, using direct-to-can milking, were used to compare utensil cleaning with hot detergent solution followed by hypochlorite on one farm and steam on the other, with immersion of the complete milking equipment in 5% caustic soda between milkings. Control and caustic treatments were used alternately for periods of 8 weeks for a total of 8 months.

Bacteriological tests made at weekly intervals on fresh milk and milk aged for 24 hr. at 22° C. showed little difference between the control methods, which involved brushing the milk contact surfaces, and the caustic soda method where there is no brushing.

The majority of micro-organisms in the bulk milk came from the udder and the utensils contributed little to the milk. It appeared that where utensils are satisfactorily cleaned, milking technique will be the factor which mainly affects keeping quality.

A study of the predominant flora revealed that milk from equipment cleaned by immersion in caustic soda had a simpler flora (mainly micrococci) than the control treatments.
588. The influence of the content and composition of protein in milk on the manufacture of cottage cheese
Authors: Henson J. H. , Miller T. B.
Published: June 2009

1. The problem of unsatisfactory curd formation in cottage-cheese manufacture has been studied in relation to milk composition.

2. Addition of calcium chloride to the milk did not produce significant improvement.

3. There was a distinct breed difference in the curd formation; Jersey milk produced satisfactory curd whilst Friesian milk invariably produced unsatisfactory curd.

4. Dilution of Jersey milk to the same level of precipitable casein as Friesian milk resulted in unsatisfactory curd.

5. The presence of 10 % Friesian milk in Jersey milk rendered the latter unsatisfactory.

6. The Walker formol titration for determination of casein gave significantly high values with Friesian milk. This is attributed to the different distribution of nitrogen in Friesian milk.
596. Steam distillation of taints from cream: I. Theoretical considerations and properties of the reference substances, diacetyl and acetoin
Authors: McDowall F. H.
Published: June 2009

The rate of removal of a dissolved tainting substance from cream by steam-distillation treatment is dependent in part on the relative volatility (or boiling point) of the pure substance, in part on the temperature of steam distillation, and in part on the influence of water on the vapour pressure of the tainting substance in dilute solution (i.e. on the activity coefficient, γ).

The application of Raoult's law and Henry's law to the problem of removal of taints from cream is discussed. For the dilute solutions commonly encountered in cream Henry's law can be expected to apply.

The equilibrium relationships for diacetyl and acetoin used as reference substances in investigations on cream-deodorizing equipment have been determined. The equilibrium coefficient for diacetyl in water at concentrations up to 50 p.p.m. in the liquid, as measured by the continuous equilibrium vaporization method, is 39·3. With rise in concentration above 50 p.p.m. in the liquid the coefficient decreases. At 100 p.p.m. it is 32 and at 1000 p.p.m. it is 20. The coefficient for acetoin in water at all concentrations up to 1·2% in the liquid is constant at 1·29. The activity coefficient for diacetyl in concentrations up to 50 p.p.m. was found to be 26·4 and for acetoin at concentrations up to 1·2%, 5·4.

For diacetyl the solubility partition coefficient as between butterfat and water rises from 0·47 at 100° F. to 0·74 at 180° F. For acetoin the partition coefficient remains constant at 0·18–0·19 over this range of temperatures. Correspondingly diacetyl is removed equally easily from butterfat and from water, whereas acetoin steam-distils much more readily from butterfat than from water.
638. The influence of cultural conditions on the characteristics of Streptococcus cremoris, strain HP
Authors: Whitehead H. R. , Briggs C. A. E. , Garvie Ellen I. , Newland L. G. M.
Published: June 2009

Cultures of a strain of Streptococcus cremoris HP after maintenance in two countries under different conditions preserved their main characteristics unchanged for 18 years.
657. Factors influencing the vitamin content of milk fat: III. Seasonal changes in the vitamin A and carotenoid content of the blood plasma and milk fat of cows on pasture
Authors: McGillivray W. A.
Published: June 2009

1. The levels of vitamin A alcohol and ester, carotene and xanthophyll in the blood plasma of six cows, grazed out-of-doors on pasture under typical New Zealand conditions, have been followed throughout one lactation. The same constituents have also been followed in the milk fats of these animals and in commercial factory butters over the same season.

2. The seasonal trend in the vitamin A and carotenoid content of New Zealand milk fat is a reflexion of the changing level of these substances in the blood plasma.

3. The decreased level of carotene, xanthophyll and vitamin A ester in the blood plasma over the summer months is consistent with a decreased absorption or utilization of carotenoids over this period.

4. Throughout the year the vitamin A in the milk fat is predominantly in the ester form with no increase in vitamin A alcohol indicative of any increased utilization of hepatic vitamin A reserves.

The author is indebted to the Department of Scientific and Industrial Research for a grant towards this investigation; to Mr M. R. Patchell and the farm staff of The Dairy Research Institute (N.Z.) for assistance in the collection of milk and blood samples; to Dr F. H. McDowall, Mr A. K. R. McDowell and the staff of the Chemistry Laboratory, The Dairy Research Institute (N.Z.), for the preparation of the fat samples and for the supply of factory butters. The assistance of Miss Fay Frecklington and Miss Jane Monroe with part of the experimental work is also acknowledged.
701. A comparison of dried skim-milk and white fish-meal as protein supplements for fattening pigs
Authors: Barber R. S. , Braude R. , Mitchell K. G.
Published: June 2009

1. Thirty-six 9–11-week-old Large White pigs in nine blocks of four litter-mates were individually fed on diets containing either white fish-meal or various amounts of dried skim-milk as the protein supplement. The pigs were fed according to live weight and a scale up to a maximum of 6½ 1b. of meal/pig/day.

2. There were no significant differences in rate of growth or efficiency of food utilization between pigs given the diets containing as protein supplements either 10% white fish-meal reduced to 7% at 130 1b. live weight, 10% dried skim-milk reduced to 7%, or 15% dried skim-milk reduced to 10½%.

There was, however, a trend towards an improvement in both rate of growth and efficiency of food utilization with increasing levels of skim-milk in the ration, and the differences between the high skim-milk diet (20 reduced to 14%) and the low (10 reduced to 7%), and also between the former and the fish-meal diet, reached statistical significance.

3. The difficulties of drawing any definite conclusions from the results about the relative value of the protein in white fish-meal and dried skim-milk were discussed in relation to (a) the probability that the white fish-meal diet used contained over-generous supplies of protein, and (b) the higher energy value of dried skim-milk as compared with white fish-meal.

4. The commercial grading of pigs on all four treatments was very good. The carcass measurement data indicated a tendency for the skim-milk diets, particularly those containing either 10 or 15%, to result in some increase in both back fat and belly thickness. The possibility that this was associated with the higher energy/protein ratios in the skim-milk as compared with the white fish-meal diets was discussed.
702. Winter feeding of dairy cows: V. A comparison of the relative value for milk production of artificially dried cocksfoot and a timothy/meadow-fescue mixture grown both in spring and in autumn
Authors: Campling R. C. , Holmes W.
Published: June 2009

1. An experiment was conducted to compare the relative value for winter milk production of artificially dried cocksfoot and a mixture of timothy and meadow-fescue each cut in the spring and autumn.

2. A double balanced 4×4 Latin square design with eight Ayrshire cows and four periods each of 3 weeks' duration was used.

3. The dried grasses were fed in equal amounts (17 lb./cow/day) and equal quantities of each grass were consumed in terms of dry matter. Approximately half the total dry matter intake was grass.

4. No differences were detected between the cocksfoot and the timothy/meadow-fescue mixtures in their value for milk production.

5. With both cocksfoot and timothy/meadow-fescue the spring-grown grass gave slightly higher milk yields than the autumn-grown grasses but the differences were not statistically significant.

6. Feeding the spring-grown dried grasses led to a slightly higher solids-not-fat content in the milk than when the autumn-grown grasses were fed.

7. The feeding of the autumn grown timothy/meadow-fescue grass mixture was associated with a significant loss of live weight in the cows. It was suggested that this loss of weight was due primarily to changes in the amount of the contents of the rumen and intestines.
712. The relation between the chemical composition of milk and the stability of the caseinate complex: I. General introduction, description of samples, methods and chemical composition of samples
Authors: White J. C. D. , Davies D. T.
Published: June 2009

1. This paper is Part I of a series dealing with the relation between the chemical composition of milk and the stability of the caseinate complex to ethanol (Part II), rennet (Part III) and heat (Part IV).

2. A description is given of the milk samples, which were taken from herd bulk milk, from individual cows in different stages of lactation and also from cows with subclinical mastitis.

3. The methods used to measure the stability of the caseinate complex to the three coagulating agents are described, together with the methods used to make a detailed chemical analysis of the milk samples.

4. The chemical composition of the samples is given and also the relation between composition and stage of lactation, and the interrelations of the concentrations of certain milk constituents.

The authors thank Miss M. H. King and Miss R. E. M. Stevenson for technical assistance, Mr N. H. Strachan and Mr R. C. Voss (West of Scotland Agricultural College) for the sodium and potassium determinations and Dr P. S. Blackburn for the differential cell counts and bacteriological examination of the milks.
722. An analysis of the performance of an ultra-high-temperature milk sterilizing plant: III. Comparison of experimental and calculated sporicidal effects for a strain of Bacillus subtilis
Authors: Burton H. , Franklin J. G. , Williams D. J. , Chapman Helen R. , Harrison A. Jean W. , Clegg L. F. L.
Published: June 2009

The previous papers of this series (1,2) have shown how the bactericidal efficiency of a flow-type heat exchanger may be predicted from physical measurements, and have given the necessary calculations for a small plate-type ultra-high-temperature sterilizing plant made by the A.P.V. Co. The purpose of this paper is to show the degree of agreement between practice and prediction from theory.
Steam distillation of taints from cream: VII. Butterfat/water distribution coefficients in relation to vapour/liquid equilibrium coefficients for tainting substances in cream
Authors: McDowall F. H.
Published: June 2009

1. The relationship between vapour/liquid equilibrium coefficient for a tainting substance in cream (mc) as compared with the coefficient for the substance in skim-milk (ms) at 100° C. is given by the formula

where F is the percentage fat content of the cream, and k is the butterfat/skim-milk distribution coefficient at 100° C.

2. The values for the vapour/liquid equilibrium coefficients for acetoin, diacetyl, acetylpropionyl, acetyl-iso-butyryl, acetylvaleryl, acetylcaproyl and acetylbenzoyl in cream, computed by the formula from the equilibrium coefficients for the substances in 4·5% lactose solutions and the distribution ratios at 100° C, were in good agreement with the experimental results for these substances in cream.

3. It was shown that high solubility of a substance in butterfat relative to solubility in skim-milk greatly reduces the steam volatility of the substance from cream.

4. It was concluded that steam volatility of a substance from cream may be affected by temperature of deodorization because of the effect of temperature on the butterfat'skim-milk distribution coefficient.
Lactobacilli in Cheddar cheese
Authors: Johns C. K. , Cole Shirley E.
Published: June 2009

The numbers of lactobacilli present in milk for cheese-making and in the cheese at various stages of ripening, have been determined for 38 Cheddar cheeses made during studies on flavour enhancement. These organisms multiplied rapidly even during the first few days of curing. Maximum levels were attained at 3–6 months; at 1 year counts had declined appreciably.

Flavour intensity in the experimental cheese appeared to be correlated with the level of lactobacilli present in (a) milk at the start of cheese-making and (b) at subsequent stages of ripening. These two count levels were usually closely correlated. Factory raw milk had the highest counts and gave the highest degree of flavour, followed by similar milk pasteurized and inoculated with selected strains of lactobacilli.
Phage resistance in pure strains of cheese starter streptococci
Authors: Robertson P. S.
Published: June 2009

The ratio of phage-resistant to phage-susceptible chains in five strains ofStreptococcus cremorisand two ofStr. lactiswas investigated. It was shown that this ratio varied between strains and was decreased when the cultures were subcultured with extremely small inocula ( <50 chains/ml) and increased with relatively large inocula (1%). It is suggested that resistant cells arise by mutations occurring in the absence of phage.
Studies on the manufacture of sweet cream starter butter: III. Effect of age of starter cultures at time of inoculation
Authors: McDowall F. H. , Singleton J. A. , Le Heron B. S.
Published: June 2009

The use of starter cultures prepared 3 days, 2 days and 1 day before inoculation at the 1% level into cold cream in the making of sweet cream starter butter was investigated. With Streptococcus diacetilactis starter there was little effect of age of starter on diacetyl production in the cream and on the quality of the fresh butter, but when 3-day-old culture was used in the cream there was a slight reduction in the butter quality after 4 and 8 months' storage. With the mixed commercial cultures Camb and F.D. increase in age of the culture led to reductions in diacetyl production in the cream. The difference was attributed to the effect of holding for the longer time under acid conditions on the equilibrium between streptococci and leuconostocs in the mixed culture. The age of the Camb culture had no effect on the grade of the butter, but holding the F.D. culture for 3 and 2 days instead of for 1 day caused a fall in grade of the butter after storage for 4 and 8 months at 14 °F.
Physical properties of milk fat: I. Influence of chemical modification
Authors: de Man J. M.
Published: June 2009

Interesterification of milk fats resulted in increased softening points, hardness and high melting glycerides (HMG). Increasing the content of trans-unsaturated acyl groups in milk fat resulted in increased softening points and hardness. While the increased solid fat content after interesterification occurred mostly at the higher measuring temperatures, the increase due to isomerization occurred mainly at the lower measuring temperatures. However, in both cases hardness was increased at all measuring temperatures. These results indicate that glyceride structure and trans-unsaturated acyl content influence the physical properties of the solidified fat.
The effect of hydrogen peroxide on the nutritive value of milk
Authors: Gregory Margaret E. , Henry Kathleen M. , Kon S. K. , Porter J. W. G. , Thompson S. Y. , Benjamin Margaret I. W.
Published: June 2009

Treatment of milk with 0·05% (w/v) H2O2 for 8 h at 24°C had no significant effect on the concentrations of seven of the B-complex vitamins or of the fatsoluble vitamins A and E or of carotene. Rat tests showed that the nutritive value of the milk proteins was slightly reduced. This finding was confirmed by microbiological tests with Streptococcus zymogenes, which also showed that the loss was probably connected with that of methionine. The concentration of H2O2 used was effective in controlling bacterial growth during the incubation period, even in a sample of milk with a high initial bacterial count.
The effect of level of concentrate feeding before and after calving on the production of dairy cows
Authors: Castle M. E. , Watson J. N.
Published: June 2009

Two levels of steaming-up and two levels of concentrate feeding after calving were compared in a feeding trial extending over a complete lactation using sixteen autumn-calving Ayrshire cows in each of 2 years. On the high and low levels of steaming-up 3·3 and 1·6 cwt of concentrates respectively were fed per cow in the 5 weeks before calving. On the high and low levels of concentrate feeding after calving the concentrates were fed at rates of 4·1 and 2·2 lb per 10 lb of milk respectively from the third day after calving until spring grazing began. The total weight of concentrates fed after calving was 25·8 cwt per cow on the high treatment and 12·1 cwt on the low treatment. All the cows grazed good pasture in the autumn and the following spring and had a ration of 9–11 lb of hay and 50–90 lb of grass silage per day during the winter feeding period. During this period the estimated mean intakes of starch equivalent on the high and low concentrate treatments were 17 and 13 lb/day, which were equivalent to 122 and 103% of Woodman's standards respectively.

Milk yield, milk quality, length of lactation and live weight were not affected by the difference between the steaming-up treatments, and no interaction between steaming-up and post-calving treatments was found. Average milk yields in the first 70 and 140 days after calving and in the complete lactations were all higher on the high post-calving concentrate treatment than on the low treatment, and the response per 1 lb additional starch equivalent fed was 1·05 lb milk. The fat content of the milk was similar on all treatments whereas the S.N.F. content increased from 8·64% on the low treatment to 8·82% on the high treatment, giving a response of 0·045% S.N.F. per 1 lb of additional starch equivalent.

Larger losses in live weight occurred on the low treatment in the first 10 weeks after calving than on the high treatment, but in both groups the weights were almost identical after 45 weeks.