bluuebunny/crossref_metadata_2025 huggingface dataset:
362. Studies in the bacteriology of milk: I. The streptococci of milk
Authors: Abd-El-Malek Y. , Gibson T.
Published: June 2009

The streptococci occurring in raw and pasteurized milks of varying purity have been investigated. The organisms were placed in five main groups by testing for the hydrolysis of arginine, growth at 45 and at 8–12° C, survival in milk at 63° C. for 30 min. (measured by a semi-quantitative plating method), action on litmus milk, and the ability to form CO2from glucose (tested by a cultural method). The groups thus distinguished are:

(1) Organisms of bovine mastitis.

(2)Str. bovisandStr. thermophilus. A clear-cut separation of these species was not obtained by tests for growth at 50° C, the hydrolysis of aesculin, or the fermentation of maltose or salicin; but, with suitable precautions, action on both maltose and salicin provides a differentiation. Certain strains ofStr. bovisdiffer from the typical form of that species in their ability to proliferate over a wider range of temperature and in higher concentrations of salt and methylene blue and in their failure to split aesculin.

(3)Str. lactisandStr. cremoris, which were differentiated by tests for the hydrolysis of arginine and ability to grow at 40° C.

(4)Str.faecalisand its varieties. Many of the strains are non-haemolytic but otherwise indistinguishable fromStr. durans. The formation of acetoin from citrate and from glucose are common but not universal properties in the enterococcus group.

(5) Heterofermentative streptococci. The majority of the strains were identified asStr. kefir. Str. citrovorus, which was isolated only occasionally, was distinguished by its low maximum temperature (under 37° C), weak resistance to heat and by fermentation reactions.

Raw milk was found to containStr. kefir, Str. lactisand the mastitis organisms more frequently than the other species.Str. thermophilusandStr. boviswere the dominant forms in freshly pasteurized milk. Pasteurized milk held at 10–22° C. until it became tainted yieldedStr. kefirandStr. faecalisand, at the higher temperatures,Str. bovisandStr. thermophilus.
370. The reaction between milk protein and reducing sugar in the ‘dry’ state
Authors: Lea C. H.
Published: June 2009

‘Dry’, dialysed milk protein was stored for 6 months at 37° C. and 55% relative humidity alone and in the presence of small proportions of glucose, of high proportions of lactose and of sucrose, and of mixtures of these sugars.

The reducing sugars combined with free amino-groups of the protein, apparently in a 1:1 ratio; sucrose did not. The reaction did not proceed to completion, probably owing to difficulty of access of the reactive groups to one another. Only when the sugar-amino reaction occurred did discoloration ensue.

Glucose reacted more rapidly with the protein than did lactose, and the complex formed became discoloured and insoluble in both cold and hot water much more rapidly.

Sucrose and lactose both greatly delayed the onset of glucose-induced insolubility, lactose being the more efficient of the two. They did not prevent discoloration.

The protein alone became insoluble in cold but not in hot water after prolonged storage; but did not discolour. This change was prevented by sucrose. The behaviour of lactose was inconsistent, loss of solubility being accelerated in one experiment and retarded in another.
409. Apparatus for studies on disinfection of milking machine teat cups
Authors: Lineham G. E. K.
Published: June 2009

Two pieces of apparatus are described for use in studies on disinfection of milking machine teat cups: (1) an easily constructed attachment for a standard milking machine allowing the collection of the total yield from each individual quarter; and (2) an apparatus designed to reproduce as closely as possible machine milking and to allow an equal quantity of the same sample of infected milk to be ‘milked’ through each of four teat cups which will be infected to the same extent. These infected teat cups can be used to provide comparable results in trials on different disinfection procedures.
420. The colloidal phosphate of milk: I. Composition and titrimetric estimation
Authors: Pyne G. T. , Ryan J. J.
Published: June 2009

1. A new type of oxalate titration permitting determination of the nature of the colloidal phosphate of milk has been developed.

2. About 88% of the colloidal phosphate appears to be tricalcic, the remainder is thought to be dicalcic.

3. Estimates of tricalcium phosphate by the Ling titration are distinctly higher than the foregoing. This would seem to be due mainly to the divergent pH values to which milk and whey are titrated in this method. There is no evidence of any conversion of colloidal dicalcium to tricalcium phosphate during the Ling titration, as had been suggested.
430. Studies of the nature of subjective judgements in cheese-grading
Authors: Harper R. , Baron M.
Published: June 2009

In grading Cheshire cheese, assessments are made of the ‘body’, ‘texture’, ‘crumbliness’, flavour and overall quality. In commercial grading in this country (England) it is not usual to apply a scoring system to these various characteristics, although, in judging cheese for show purposes, points would be assigned to each item. American practice, at least according to the literature, suggests that score cards are in general use for each particular dairy product, so that the various items may be assessed in quantitative terms. For experimental purposes, where it is required to assess the effect of specific variations in conditions of manufacture or storing of the cheese, or to assess the relation between instrumental tests and the judgements of graders and others, some quantitative form of expression of these judgements is essential. However, it has to be borne in mind that the process of forcing the judgement into an arbitrarily selected numerical scale may lead to a certain amount of distortion and may not be entirely satisfactory. Modifications of procedure desirable in the interests of statistical planning may also be unacceptable, in view of the dislocation they may cause to the ingrained habits of the professional foodgrader.
457. The sale of surplus calves in Great Britain, 1940–50
Authors: Phillips R.
Published: June 2009

1. A record has been made of the volume of the trade in surplus calves in Great Britain for the period 1940–50; it has averaged one and a quarter million calves each year. The highest numbers sold in any year occurred in 1946 (Fig. 1).

2. The seasonality of calf sales showing an annual increasing volume of autumn calves (with October the peak month) is a reflexion of the development of dairying and of the priority for winter milk (Fig. 2A and Fig. 3, Sheets 1 and 2).

3. Of the total calves 46.7% were classified as bobbies and 50.8% as veals. The small remainder consisted of stirkies (other strong calves), casualties and those unfit for human consumption (Table 1).

4. Nearly 63% of the veals were 3rd quality and only about 12% of the 1st quality.

5. The seasonality of veal deliveries showed a maximum proportion in June (with a correspondingly lower proportion of bobbies in that month). The maximum numbers however correspond with the maximum gross deliveries in October (Fig. 2B).

6. There has been an annual deterioration in the quality of the surplus calves as indicated by: (a) the lower proportions of veals in the total during each year, (b) the higher proportions of 3rd quality veals in the total veals each year, and (c) the reduction in the monthly proportions of 1st quality veals.

7. An attempt has been made to relate the calf sales to calf births and populations of under 1-year-old cattle and of total cows.

8. It is estimated that the calf crop as a percentage of the total cows has improved since 1940, and for the last 8 years it has averaged 92%.
460. Studies of the secretion of milk of low fat content by cows on diets low in hay and high in concentrates: I. The effect of variations in the amount of hay
Authors: Balch C. C. , Balch D. A. , Bartlett S. , Cox C. P. , Rowland S. J.
Published: June 2009

1. Twelve Shorthorn cows were used for an investigation into the effect of diets low in roughage and high in concentrates on the fat content of milk.

2. An experiment was conducted with initial and final control periods. During the control periods all the cows received daily 17 to 21 lb. of hay, 30 lb. of mangolds and 4 lb. of a balanced concentrate mixture per 10 lb. of milk. In the period of experimental treatment, lasting 4 weeks, a control group of four cows remained on this diet. Two other similar groups received daily only 6 and 2 lb. of hay, but this was supplemented with 9 lb. of a concentrate mixture low in fibre and protein. The same allowances of mangolds and of concentrates for production were given to these as to the control group.

3. The mean fat content of milk produced in the last 2 weeks of the period of experimental treatment by cows receiving the diets low in roughage was 0·49 % (group receiving 6 lb. of hay) and 0·59% (group receiving 2 lb. of hay) below that produced by the cows receiving the control diet, these differences being statistically significant. In the group receiving daily 6 lb. of hay the drop in fat content was accompanied by an increase in the yield of milk and there was only a small fall in the yield of milk fat, but in the group receiving daily 2 lb. of hay there was a significant fall in the yield of fat. The latter fall represented a loss of 18·9% of the fat as compared with the control group. The fat content of the milk and the yield of milk rapidly returned to normal when the cows reverted to 18 lb. of hay per day.

4. The butterfat produced by the cows receiving diets low in roughage had a higher iodine value and lower softening point than that from the control cows. The fat from the group receiving daily 2 lb. of hay, but not that from the group receiving 6 lb. of hay, had a distinctly lower Reichert value than fat from the control group. The treatments caused no change in the saponification value.

5. The level of solids-not-fat in the milk was not affected by reduction in the roughage intake.
462. The keeping quality of composite milk
Authors: Babad J. , Shenhav-Hetman A.
Published: June 2009

The keeping quality of various mixtures, made up of raw milk and skim milk-powder in varying proportions, has been studied. It has been found that the keeping quality of unpasteurized samples containing milk powder was slightly better than that of raw milk. The keeping quality of the pasteurized mixtures was satisfactory during the time of storage for 40 hr. at 23 and 18° C. and for 60 hr. at 10° C.
463. Changes with temperature in the viscosity of whole milk
Authors: Cox C. P.
Published: June 2009

1. The results of experiments on the changes with temperature in the relative viscosity and viscosity of whole milk have been considered.

2. Some inconsistencies have been traced and amendments proposed.

3. It has been suggested that values for the relative viscosity and viscosity of whole milk cannot usefully be regarded as independent of the experimental circumstances in which the observations were obtained.

4. Empirical curves have been calculated for the viscosity-temperature relations, in forms convenient for practical use in circumstances similar to those of the experiments examined.
469. The effect of tocopherol and carotene supplements on the vitamin A potency of New Zealand butterfat
Authors: McGillivray W. A.
Published: June 2009

1. Reasons for the seasonal variations in the vitamin A potency of New Zealand butterfat have been investigated. Adequate carotene for the production of butterfat of maximum potency has been shown to be present in New Zealand pasture throughout the year, but during the summer period this carotene is relatively non-available to dairy cows.

2. In experiments with monozygotic twins grazing average summer pasture it has been shown that a supplement of 1 g. of tocopherol per day increased both carotene and vitamin A levels in the milk fat, the total vitamin A potency being raised from a typical midsummer minimum of 34 i.u./g. fat to a value approaching the maximum late winterspring level of about 50 i.u./g. This maximum level was unaffected by increasing the tocopherol supplement to 3 g. per day or by supplying 300 mg. of carotene in a readily available form in addition to the 3 g. tocopherol.

3. Supplementing the summer pasture with 300 mg. of carotene in oil without tocopherol was without effect on the potency of the fat, supporting the conclusion that the carotene intake was already adequate.

4. A significant correlation was found to exist between vitamin A potency and tocopherol content of New Zealand butterfat.

5. It is suggested that the low vitamin A potencies may be associated with the high percentage of clover in the summer pastures.
470. The distribution of fat-globule size in sow's milk: I. The effect of sampling at intervals throughout milking
Authors: Whittlestone W. G.
Published: June 2009

An improved method for the determination of fat-globule size distribution has been worked out and applied to samples of sow's milk drawn sequentially. The distribution patterns for the globule sizes of sow's milk have been determined. Globules range in size from less than ½μ to over 7μ. The maximum number of globules occurs at different sizes in different sows, the largest maximum size group so far recorded being 2–2·5μ, the smallest maximum group being 0–0·5μ. There is no marked trend in size with stage of milking, though usually the maximum size is less for later milkings if it changes.

The strippings of sow's milk, unlike those of the cow, do not appear to be richer in fat than the earlier milk. Also unlike the cow, the globules of sow's milk do not cluster or clump (see Fig. 1). This explains the slow rate of creaming of sow's milk.
474. A note on the serological classification of Streptococcus diacetilactis (Matuszewski et al.)
Authors: Briggs C. A. E.
Published: June 2009

Streptococcus diacetilactis, isolated from spontaneously soured potato mash, was first described by Matuszewski, Pijanowski and Supińska in 1936(3). Its essential features included the production of large amounts of lactic acid and volatile products (including diacetyl), and it differed from the ‘lactis-cremoris’ group primarily in the production of carbon dioxide in milk, the utilization of citrate and in its vegetable origin. More recently, in his investigation of certain diacetyl-producing and citric acid-fermenting streptococci from milk and from starter cultures, Swartling(5) showed that strains which resembled closely the Str. diacetilactis of Matuszewski et al. belonged to serological group N. In an addendum to his paper, Swartling states that this observation has been confirmed by me with a freshly isolated strain of Str. diacetilactis (no. 2) received from Prof. Pijanowski and Dr Supińska the purpose of this Note is to record the experimental evidence for that statement.
484. Studies in the bacteriology of milk: IV. The Gram-negative rods of milk
Authors: Abd-El-Malek Y. , Gibson T.
Published: June 2009

Using non-selective methods of isolation, the species that was detected with greatest frequency in raw milks of varying purity isAlcaligenes viscosus. The majority of the cultures do not produce a ropy condition in milk or other media. In some strains the oxidation of citrate, and hence the production of alkalinity in milk, is slow and erratic, being dependent on the occurrence of a mutation. The only Gram-negative rod detected in laboratory-pasteurized milk wasA. tolerans n.sp., a description of which is given. That species is similar in general character toA. viscosus but differs principally in its greater resistance to heat, its inability to attack fats, and its erratic and usually poor growth on laboratory media. Greatly improved growth on nutrient agar is obtained by the addition of lactate and relatively high concentrations of ferrous or ferric salts.
492. The importance of psychophysical errors in subjective judgements of firmness of Cheshire cheese
Authors: Sheppard D.
Published: June 2009

1. Ratings for firmness which were carried out on 150 Cheshire cheese at 2 weeks old, by three judges, were examined so as to extract the expected psychophysical errors.

2. It was found that the value for firmness given to any particular cheese tended to be a function of the average firmness of the group of cheese in which it was judged, so that a cheese of a given objective value would be given a different rating according to its position in the series being judged.

3. A cheese of a given value presented after a firm one is judged softer than if it had been presented after a soft one. This contrast effect was masked by the influence of the group as described in (2). Nevertheless, it seems probable that contrast effects influence the judgements.

4. The frequency distributions of the subjective judgements were examined, and it was noted that the ‘semi-expert’ judge gave subjective values which approximated very closely to a normal distribution, more nearly so than the judgements of the other two judges.

5. Reasons are suggested for the differences in the values allotted to the cheese as judged by the different judges.

6. Some suggestions are made for eliminating the effects described.
506. The importance of machine milking rate in dairy cow management and breeding
Authors: Dodd F. H. , Foot A. S.
Published: June 2009

An analysis has been carried out on the milk yield, milk composition and milking-rate records collected in one herd of dairy cows.

It has been shown from the results of eighty-six heifers that for each pound per minute increase in inherent milking rate (i.e. peak flow) the standard lactation yield increases by 419 lb., the maximum daily yield by 0·9 lb., the lactation length by 8 days and the persistency index by 10 days, whilst the lactation solids-not-fat percentage decreases by 0·03 and the fat percentage by 0·04. All except the last coefficient were significant, although it was also shown that the relationship with solids-not-fat percentage was due to an interaction. Similarly, by the calculation of partial regression coefficients it was demonstrated that the relationship between milking rate and standard lactation yield was due to the effect of milking rate on maximum daily yield, lactation length and persistency.
518. The problem of fishiness in butter
Authors: Munro P. , Barnicoat C. R.
Published: June 2009

Chemical factors reputed to promote fishiness in butter were studied. Attempts were made to reproduce fishiness in experimental churnings of butter by deliberately applying factors reputed to cause the defect, viz. low pH, high salt content, lack of pasteurization, traces of copper, borates—singly and in combination.
547. A recording tympanometer for the measurement of intramammary pressure in the cow
Authors: Phillips D. S. M.
Published: June 2009

A manually operated tympanometer pressure recorder of simple construction designed for recording the changes in pressure in the lower cistern of the mammary gland of the cow during let-down and milking is described. The instrument makes possible the measurement of the internal milk pressure without the need for direct access to the milk cistern. The measurements are made with a tympanometer unit which is held firmly against the outside wall of the udder.
550. Colour changes in heated and unheated milk: I. The browning of milk on heating
Authors: Burton H.
Published: June 2009

Methods for measuring the reflectance of milk are described. The effect of heating is to reduce the reflectance of whole and separated milk progressively towards the blue end of the visible spectrum. The reflectance of cream is almost unaffected. The measurement of reflectance at the blue end of the visible spectrum is shown to be a useful method for the determination of the brownness of milk. The variation of rate of browning with temperature and with pH and the effect of storage on brownness are given.
552. Heat-induced acidity in milk
Authors: Grimbleby F. H.
Published: June 2009

An inverse relationship has been demonstrated between the titratable acidity and formol titre of raw separated milk heated at temperatures of 60, 70 and 80° C. suggesting that the combination of lactose and protein, with the elimination of basic amino groups attached to protein, is one of the main reactions responsible for the heat-induced acidity. At temperatures of 90 and 100° C., when thermal decomposition of protein takes place, heat-induced acidity develops very rapidly and is accompanied by a marked increase in the number of basic amino groups and in the number of these groups which combine with lactose. Below 80° C. the development of acidity was not accompanied by discoloration of the millk, but at 80° C. and above, browning of the milk occurred. The relation between heat-induced acidity and browning is discussed.
559. The inhibition of micro-organisms by raw milk: III. Distribution and properties of two inhibitory substances, lactenin 1 and lactenin 2
Authors: Auclair J. E.
Published: June 2009

1. The L1 and L2 contents of a number of samples of bulk milk and milk from separate quarters of cows with and without infection have been determined. The milk of cows sensitive to mastitis has about the same content as the milk from resistant ones.

2. The effect of heat on L1 and L2 has been observed for various combinations of time and temperature. Heat treatment corresponding to the legal standards of pasteurization destroyed 50% L1, but did not affect L2.

3. The inhibitory action of L1 and L2 has been observed on several micro-organisms. All the organisms tested were sensitive to lactenin in sterilized milk. Stimulatory substances have been shown to interfere with the inhibition by lactenin.

4. The action of lactenin on the growth of Str. pyogenes has been studied. The effect of hydrogen peroxide on lactenin has been compared with that of cysteine.
585. A phosphatase test for pasteurization of milk using disodium phenolphthalein phosphate as substrate
Authors: Tulloch W. J.
Published: June 2009

1. Details have been given of a modified Stiven test for determining the efficiency of pasteurization in milk.

2. A ‘long’ form and a ‘short’ form of the test have been described.

3. The ‘long’ and ‘short’ tests have been compared with the Aschaffenburg & Mullen and Kay & Graham tests.

4. The work has led to the following conclusions:

(a) The ‘long’ Stiven test seems best to distinguish between exposure for 24 min. and exposure for 30 min. to 62·5° C, though compared with the other three tests this ‘long’ Stiven test as assessed in the present work is possibly too stringent.

(b) There was little difference between the results of the ‘short’ Stiven test, the Aschaffenburg & Mullen and the Kay & Graham tests when used for the routine examination of specimens.

(c) The ease of performance and the stability of the reagents make the Stiven test convenient to use, and it should be helpful to those who have difficulty in matching blues and yellows.

(d) It should be of value as a confirmatory procedure.
586. Colour changes in heated and unheated milk: IV. the theoretical background to the reflectance changes in separated milk
Authors: Burton H.
Published: June 2009

The theory of the scattering of light in colloidal solutions is considered. As a result it is suggested that the reflectance changes in milk which involve a rise or fall in the general level of reflectance are caused by an increase or decrease in the mean size of the colloidal particles. Whether the particles responsible are the casein micelles or the soluble protein depends on the phenomenon to be explained.

The change in reflectance on the browning of milk, which is dependent on wavelength, is considered to have a more complex cause, involving the production of absorbing molecules.
587. Fluorescence microscopy of fat in milk and milk powder
Authors: King N.
Published: June 2009

The fat globules in milk and cream by taking up the fluorescent dye phosphine from aqueous solution are rendered fluorescent, and show under the blue light fluorescence microscope a bright yellowish green coloration against the black background. Even very small fat globules (in homogenized milk, cream, skim milk, or buttermilk) and very thin fat layers on the milk-air boundary or on glass can be distinguished owing to the high contrast.

By using glycerol containing two fluorochromes, phosphine for the fat and basic fuchsin for the proteinaceous matter, a very sharp differentiation of these two components in milk-powder particles is attained. Differences in the state of dispersion of fat caused by manufacturing technique and storage conditions, and affecting the properties of powders, are clearly made visible.
591. The outdoor rearing of calves on grass with special reference to growth rate and grazing behaviour
Authors: Roy J. H. B. , Shillam K. W. G. , Palmer June
Published: June 2009

1. Five Dairy Shorthorn male calves born in February and March 1953 and three groups of four born in each of the months February, March and April 1954 were placed out of doors on permanent pasture at birth.

2. Each calf received 6 or 8 pt. colostrum followed by approximately 45 gal. whole milk during the first 8 weeks of life, and thereafter, except for a small amount of dried grass given in Exp. 1, pasture grass comprised the sole item of diet until 6 months of age.

3. Mean growth rates for each month of life and from birth to 6 months are presented. After the first month of life, good progress was made, and it is considered that the live weights at 6 months of age are similar to those obtained with conventional methods of rearing.

4. There was a significant effect of birth weight on live-weight gain. After adjustment for birth weight, there were no significant differences in live-weight gain between February, March and April-born groups of calves.

5. Weather conditions seemed to have little effect on the incidence of scouring during the first 3 weeks of life.

6. On leys, greater weight gains were obtained than on permanent pasture.

7. No lungworm larvae were detected in faeces samples examined. In many cases there was a high level of infestation with stomach and intestinal worms as indicated by the number of trichostrongyle eggs/g. faeces. Some aspects of this infestation are discussed.

8. Satisfactory growth to 18 months of age was obtained with silage during the 6-month winter period and at grass during the following spring and summer.

9. Details of behaviour of the five calves in Exp. 1 studied at approximately monthly intervals to 6 months of age are presented.
593. Intramammary pressure changes in the lactating cow: I. Changes during the milking process
Authors: Whittlestone W. G.
Published: June 2009

Using an electrical pressure-recording system simultaneous pressure records have been made in both the milked and unmilked quarters of a dairy cow. The unmilked quarters showed a very slow fall in pressure, while, as would be expected, the milked quarter showed a steady pressure fall. Re-stimulation some time after the beginning of the experiment resulted in a rise and fall in pressure within the milked quarters, but no change when the quarter was not milked.
623. Variations in the incidence of udder infection and mastitis with stage in lactation, age and season of the year
Authors: Oliver J. , Dodd F. H. , Neave F. K. , Bailey G. L.
Published: June 2009

1. The detailed udder health records of 530 lactations have been analysed on a monthly and lactation basis, so that separate studies of the first infection rate, re-infection rate, total new infection rate and total infection and mastitis incidence for both cows and quarters could be made. These data have been used to study the relationship of stage of lactation, age and season of the year with udder infection and mastitis.

2. With advancing lactation there was a decline in the rate of first infection, reinfection, total new infection and in mastitis in infected cows and quarters.

3. In early lactation there was a marked tendency for infected cows and quarters to develop clinical symptoms.

4. During the last 4 months of lactation there was no significant rise either in infection or in mastitis.

5. There was an increase in infection and mastitis with advancing age, but infected older cows were not more liable to develop clinical symptoms than younger cows.

6. There was an indication that the longer a quarter was free from infection the greater were its chances of remaining so.

7. No major seasonal trends were found in the incidence of udder infection and mastitis, although the incidence was slightly higher in the summer months.
627. Udder infections in the ‘dry period’: V. The effect of teat disinfection at drying-off on the incidence of infections in the early dry period
Authors: Oliver J. , Dodd F. H. , Neave F. K.
Published: June 2009

1. The effect of disinfecting the skin of the teats at drying-off on the incidence of new infection in the early dry period has been studied. After the last milking of lactation the udders of alternate cows to go dry were washed with sodium hypochlorite solution (800 p.p.m.), dried, and each teat immersed in a 5% iodine tincture for 20 sec., and then again immersed 24 hr. later.

2. There was significantly (P <0·05) less new infection in cows that had teats disinfected than in control cows. This difference in infection was highly significant (P <0·01) for cows that were not infected on drying-off.

3. The treatment effect was due to a highly significant (P <0·01) reduction in the incidence of infection by Staph. aureus. New infection caused by Str. uberis was not affected.
646. The steam stripping of taints from liquids: V. The basic design of cream deodorizing equipment
Authors: Scott J. K.
Published: June 2009

A comparison is made of the stripping characteristics of the types of plant studied in previous papers of the series. The effects of alterations to the type of plant, the number of vessels used or a change in processing conditions on the volatile flavour components are illustrated by calculations for solutes having equilibrium coefficients m of 2, 10 and 50. For design purposes a hypothetical taint of m=10 is used, the final taint concentration being set at 10% (of initial) for high-taint pastures and 25% for low-taint areas. Using the above hypothetical conditions, calculated steam-demand figures are shown to agree with known typical steam-demand values. The use of a flash cooling vessel is examined and shown to effect a useful steam saving.

The effect of steam velocity on the mechanical break up of the liquid in a counterflow spray column is shown; an increase in steam flow increased the liquid side disturbance and thus reduced the liquid side resistance giving a greater rate of taint transfer, the characteristic thus more nearly following a line of constant saturation than a line of constant number of transfer units.

A number of flow circuits for deodorizing plant are described. The general conditions limiting the continued reduction in steam flow are discussed.
650. The influence of temperature on the generation time of bacteria commonly found in milk: II. Examination of partial contributions over the full lactation period of two cows
Authors: Yotis W. , Teodoro R.
Published: June 2009

An attempt to show the effect of temperature on the rate of growth of bacteria in milk was made by finding the generation times ofSalmonella typhosa, Shigella dysenteriae, Streptococcus haemolyticus, Micrococcus pyogenes aureus, Lactobacillus acidophilus, Escherichia coli, Bacillus subtilisandAlcaligenes faecalisat temperatures ranging from 4 to 60°C. Growth was quantitatively measured by means of plate counts during the logarithmic period which was previously determined for each organism. The following is a summary of the results obtained:

At 4° C. none of the micro-organisms showed evidence of multiplication during the 6hr.incubation.

As temperatures of 5–45° C. were approached the generation time decreased until the optimum temperature for each organism was reached; beyond this point a slowing of growth was observed, until at 60° C. viability was apparently lost by all the organisms.

Streptococcus haemolyticusandMicrococcus pyogenes aureushave a generation time of 37–23 min.

Salmonella typhosaandShigella dysenteriaehave a generation time of 50–26 min.

Escherichia coliandAlcaligenes faecalishave a generation time of 41–16 min.

Bacillus subtilisgrows at about the same rate asAlcaligenes faecalis.

The slowest organism of all appears to beLactobacillus acidophiluswith a generation time of 52–125 min.
652. Microscopic appearance of fat on the milk surface as affected by application of surface-active substances to the surface
Authors: King N.
Published: June 2009

Surface-active substances applied to the surface of whole milk may either bring fat globules, clumps, lenses and patches on to this surface, or sweep the surface clean of these fat forms.

In the homologous series of monohydric aliphatic alcohols, methyl and ethyl alcohols show a moderate rising action, whereas the other members from n-propyl alcohol to n-decyl alcohol are strongly active. There is only a slight difference in the activity of primary, secondary and tertiary butyl alcohols.

Ageing of milk slightly promotes the rising of fat globules on to the surface under the action of ethyl to n-amyl alcohols.

Alcohols, beginning with n-propyl alcohol, bring fat globules to the surface of milk much more strongly than does mechanical disturbance of the surface by touching with a platinum ring.

Glycerol, due to its three hydroxyl groups and a weak hydrophobic residue, is almost inactive, monobutyrin is strongly active in bringing the fat globules to the surface, while tributyrin sweeps the surface clean.

Spans and Tweens, sorbitan and polyoxyethylene sorbitan esters of higher fatty acids sweep the milk surface clean.

The author wishes to thank Mr G. Loftus Hills, Officer-in-Charge of the Dairy Research Section, C.S.I.R.O., Melbourne, for helpful discussion, and the Atlas Powder Company, Wilmington, Del., U.S.A., as well as its Australian representatives, Chemical Materials Pty. Ltd., Glebe, N.S.W., and Hardie Trading Ltd., Melbourne, for samples of Spans and Tweens.
661. The genetic connexion between body size, milk production and efficiency in dairy cattle
Authors: Mason I. L. , Robertson Alan , Gjelstad B.
Published: June 2009

1. An analysis has been made of production records and body measurements of dairy cattle from farms and special progeny testing stations in Denmark.

2. Heritability estimates of various measurements of body size and also of gross efficiency of food conversion were all in the neighbourhood of 0·50. Body weight was more closely correlated with girth than with height.

3. Milk yield had a very high correlation, both phenotypic and genetic, with gross efficiency. This was shown on theoretical grounds to be a necessary result of any standard system of feeding.

4. Correlations between production characteristics and body measurements were slight. There was some suggestion that selection for yield would increase skeletal size but decrease fleshing.

5. The best index on which to select for efficiency of food conversion under these conditions would be the yield divided by the height.
681. The chemical composition and the cell count of milk
Authors: Waite R. , Blackburn P. S.
Published: June 2009

1. The mixed evening and morning milk from 360 cows, all sampled six times during their lactation, was analysed chemically and for its cell content. A total and a differential cell count were made. Similar analyses were made on 823 samples of farm milk taken at a receiving creamery.

2. The total cell counts varied from less than 10,000 to 5,000,000/ml. and there was considerable variation in the chemical composition of samples containing similar numbers and types of cells.

3. The proportion of polymorph cells in the total count increased rapidly with increasing total count.

4. Stage of lactation had little effect on the number of cells present in the milk, but samples from cows in very early and very late lactation had been avoided. The total cell count was lowest from the 70th to 130th day of lactation with a tendency to rise after the 130th day.

5. Both the total and the polymorph cell counts of the milk increased sharply with the lactation number of the cow until the seventh lactation and then remained at a fairly constant level.

6. As the total cell count increased to an average value of 500,000/ml. there was a fall in the daily yield of milk per cow and a marked fall (0·25%) in solids-not-fat content. The latter was the result of a steady drop in the lactose content, the casein content being affected only by counts approaching 1,000,000/ml. An increasing cell count was without effect on the fat content. Possible reasons for the relatively small effect on chemical composition of high cell counts in some milks is discussed.

7. It is concluded that the presence of subclinical mastitis, as evidenced by the cell count of the milk, leads to a lowering of the solids-not-fat content.

The authors wish to thank their assistants in the Technical Chemistry and Veterinary Pathology Departments, who did most of the practical work.
688. Phage-organism relationships among strains ofStreptococcus cremoris: the selection of strains as cheese starters
Authors: Whitehead H. R. , Bush Elizabeth J.
Published: June 2009

The relationships between nineteen strains ofStr. cremorisand nineteen phage races were investigated. It was found that in addition to clear-cut lytic reactions there were other actions between some phage races and bacterial strains whereby in some cases a phage could show adaptation to a strain and become changed in host range, and in other cases could inhibit growth of a strain without any phage multiplication.

There is some evidence to indicate that bacterial strains and phage races fall into family groups within which most of the phages act in one way or another on most of the strains. The suggestion is made that the strains and races in a group may have originated from a parent bacterial strain and parent phage race.

The selection of strains ofStr. cremorisfor use as cheese starters is discussed in the light of the findings reported in the present paper. The diffculty of isolating a large number of strains unrelated in every respect is indicated.
715. The relation between the chemical composition of milk and the stability of the caseinate complex: IV. Coagulation by heat
Authors: White J. C. D. , Davies D. T.
Published: June 2009

1. The variation in the stability of milk protein to heat and the relationship between milk composition and heat stability were examined.

2. The coagulation times of the majority of the milk samples decreased by a factor of about 3 with an increase in temperature of 10°C. over the range 130–150°C. Because of the general proportionality of the coagulation times at 130, 140 and 150°C., the coagulation time at 130°C. only were used as a measure of the stability of the samples to heat.

3. The coagulation times of herd bulk milks ranged from 17·2 to 59·0 min. at 130°C., whereas the range for samples from individual cows was 0·6–86·2 min.

4. Samples of colostrum were very unstable to heat, and milk from cows in late lactation tended to have the longest coagulation times, but otherwise there was little relation between the heat stability of milk and the stage of lactation of the cow.

5. Although colostrum samples were comparatively rich in ionized calcium, their marked instability to heat appeared to be caused solely by their high content of lactalbumin plus lactoglobulin.

6. The stability to heat of the calcium caseinate-calcium phosphate complex in all samples, other than colostrum, could not be closely related either to the concentration and composition of the complex or to the composition and salt-balance of the aqueous phase.

7. When the calcium phosphate content of the caseinate complex was relatively low, the heat stability of the complex tended to be inversely related to the concentration of ionized calcium in the milk, but in general coagulation time was not related to the concentration of ionized calcium.
734. Factors influencing the vitamin content of milk fat: VIII. The influence of various factors on the utilization of carotene
Authors: McGillivray W. A. , Thompson S. Y. , Worker N. A.
Published: June 2009

1. The influence of a number of factors on the utilization of carotene by rats has been investigated. A high dose level equivalent to that derived from pasture by cows has been employed and liver storage of vitamin A has been used as a measure of the efficiency of carotene utilization.

2. Utilization was influenced by level of carotene intake, by concentration of carotene in the oil used as vehicle, by the degree of unsaturation of the vehicle and by the presence of non-digestible wax.

3. Carotene was better utilized from the rye grass and ‘low cyanide’ white clover than from ‘high cyanide’ clover, but added cyanide had little or no effect on the uptake of carotene from cyanide-free pasture or from a solution in oil.

4. In so far as the results of the investigation can be applied to cows grazing typical New Zealand dairy pasture, it seems that factors which may throw some light on the poor utilization of carotene at certain times of the year are (a) small day-to-day variation in the carotene content of the pasture, (b) variations in the ‘ether extract’ fraction of the pasture, and (c) variations in the degree of hydrogenation of the fat in the rumen.

5. Insulin and adrenalin appear to have no influence on the levels of vitamin A alcohol in the blood plasma of rats.

The results of this investigation form a section of a thesis submitted by one of us (N.A.W.) in partial fulfilment of the requirements for the degree of Ph.D. of the University of New Zealand. The authors are indebted to the Department of Scientific and Industrial Research for a Grant towards this investigation and to Miss Fay Frecklington for technical assistance; one of us (S. Y. T.) is indebted to the Royal Society, the Nuffield Foundation, and the Board of the Dairy Research Institute (N.Z.) for a travelling fellowship during the tenure of which the work reported here was carried out.
736. Physical changes in milk caused by the action of rennet: III. Effects of separation, homogenization and pasteurization and of varying calcium content on the rigidity moduli and viscosities of curd
Authors: Blair G. W. Scott , Burnett J.
Published: June 2009

1. Preliminary experiments show that homogenization, separation and pasteurization all tended to delay the onset of rigidity in renneted milk, though it must be borne in mind that the first two of these treatments were accompanied by some heating of the milk.

2. Once setting had started, homogenized and separated samples set more quickly, and pasteurized (especially over-heated) milk more slowly, than did raw milk.

3. Homogenization would seem to increase, and separation perhaps to decrease the proportion of elastic recovery of the gel which is immediate. The torsiometer, which gives an over-all measure of general consistency, agrees well with the -tube gelometer but when the latter shows an unusual ratio of immediate to slow recovery, the torsiometer follows the former modulus.

4. Increasing quantities of CaCl2 added to reconstituted dried fat-free milk progressively reduce the time needed for rigidity to make its appearance but do not greatly alter the final setting rates. All setting curves approximate to the law that, once rigidity is well established, rate of setting is proportional to the percentage of casein still unset. When the amount of added lactic acid is adjusted so as to prevent the addition of various quantities of CaCl2 from altering the pH appreciably, no great difference is found in the setting curves.

5. The relaxation times, retardation times and their ratio, called ‘the springiness number’, are not greatly affected by the treatments to which the milk samples, either whole or dried, were subjected.

6. Appreciably syneresis usually occurs in the -tube gelometer only when the curd has been strained, though very small strains are sufficient to produce it. The site of its occurrence depends on the hydrodynamic distribution of the larger fat globules. In fat-free or homogenized milk, such syneretic phenomena are either absent or very slight.
Steam distillation of taints from cream: IV. Vapour/liquid equilibrium relationships for mesityl oxide and some α-diketones as possible reference substances
Authors: McDowall F. H.
Published: June 2009

1. Measurements, by means of a continuous vaporization equilibrium still, of vapour/liquid equilibrium relationships in the steam distillation of dilute aqueous solutions showed that for mesityl oxide the relationship was linear, equilibrium coefficient (CV/CL)= 74.

2. For acetylpropionyl it was linear over the concentration range l–10 p.p.m. in the liquid, CV/CL=51, and above a concentration of 20 p.p.m. it was again approximately linear. At 20 and 50 p.p.m. in the liquid the values found for CV/CL were 34 and 21·5 respectively.

3. For acetyl-iso-butyryl it was not linear even at very low concentrations, of the order of 1–3 p.p.m. in the liquid, but there was an approach to linearity at concentrations 0–1 p.p.m., CV/CL=240. At concentrations above 1 p.p.m. in the liquid there was a steady fall in the value for the equilibrium coefficient.

4. For acetylvaleryl it was curvilinear even over the concentration range 0·1–4·0 p.p.m. in the liquid. At 0·5–1·0 p.p.m. in the liquid the equilibrium coefficient was of the order of 240. Above a concentration of 4 p.p.m. in the liquid the relationship was linear.

5. For acetylcaproyl it was approximately linear only over the concentration 0·1–0·4 p.p.m. in the liquid, CV/CL=180. At 4 and 8 p.p.m. in the liquid the coefficients were 90 and 70 respectively.

6. For acetylbenzoyl it was curvilinear at low concentrations, i.e. 0·1–0·5 p.p.m. in the liquid, CV/CL=30 decreasing to 16. Above this concentration there was a gradual fall in the equilibrium coefficient to 11·5 at 70 p.p.m. in the liquid.

7. Of the substances investigated only diacetyl and acetylpropionyl and, within limits, acetylbenzoyl were considered to be of suitable properties for use as reference substances in detailed investigations on cream deodorization equipment.