bluuebunny/crossref_metadata_2025 huggingface dataset:
144. Observations on the Ripening of Cheeses made from Raw and Pasteurized Milk
Authors: Sherwood I. R.
Published: June 2009

The proteolytic action of rennet, pepsin and trypsin upon milk pasteurized at various temperatures has been investigated. It was shown that the action of these enzymes in pasteurized milk differed from their action on raw milk. The change was especially marked over the temperature range of 150–160° F., and was shown to be due, not to alteration in the protein itself, but probably to some change in the non-protein constituents of milk

The results were applied in a study of cheeses made from raw milk and from pasteurized milk. It was demonstrated, with the aid of cheeses ripened in the absence of bacterial action, that the differences in nitrogen partition which occur between cheeses made from raw milk and from pasteurized milk could be largely accounted for on the basis of chemical alteration produced in the milk constituents by heat treatment—this alteration affecting the proteolytic action of rennet and bacteria upon the cheese curd.
153. Studies on the chemistry of Cheddar cheese making. VI. Factors affecting the relation between lactic acid and titratable acidity in wheys
Authors: Dolby R. M. , McDowall F. H. , McDowell A. K. R.
Published: June 2009

The experiments described above have shown that on the whole there is a close relationship between titratable acidity and lactic acid concentration in wheys obtained under various conditions of cheese-making. Variations in the rate of acid development or in the lactose content of the cheese milk have no significant effect on the relationship. Variations in the mineral content of the curd brought about by differences in the composition of the milk or by different acidities up to the running stage do have a certain effect. In curd with a lower mineral content there is a less complete neutralization of lactic acid and the wheys show a higher titratable acidity for the same lactate content. The differences, however, are small and affect only the wheys coming off late in the cheese-making process.
164. The nutritive value of milk supplemented with minerals as an exclusive diet for fats. Comparison of equal volumes of Summer and “winter” milk before and after laboratory pasteurization
Authors: Henry K. M. , Ikin E. W. , Kon S. K.
Published: June 2009

Milk was obtained simultaneously from cows on early pasture and from stall-fed cows receiving winter rations. By suitable blending of the morning's and evening's milkings of each milk the fat content of the two milks was equalized daily. A part of each milk was then pasteurized in the laboratory by a “holder” method. The total nutritive value of the milk was measured on rats in two separate experiments. In one the milks, supplemented with iron, copper and manganese, were fed as an exclusive diet. The four types of milk were given to twelve groups of litter-mate male rats, the intake being equalized within each group. The experiment lasted 8 weeks, and at the end no difference was found in gain in weight, body length, general appearance of the rats or composition of the carcasses. The palatability of the milks as gauged by the refusals of the rats was investigated by various statistical methods, which showed that summer milk was probably more palatable than “winter” milk, but that pasteurization had no effect.

In the second experiment the intake of milk was limited to 20 ml. daily, but the rats were given in addition unlimited access to a basal diet of casein, sugar and salts. This experiment was also carried out on groups of four litter mates (four groups of does and seven groups of bucks). After 8 weeks 5% brewer's yeast was added to the basal diet, resulting in a marked increase of the growth rate of all the groups. At the end of the 8 weeks, the gains in weight, intakes of basal diet, and gains per gram of solids ingested were compared. The only statistically significant differences were in favour of pasteurized summer milk when compared with summer raw and with “winter” pasteurized.
168. Bitterness and thinning in canned cream
Authors: Nichols A. A. , Howat G. R. , Jackson C. J.
Published: June 2009

1. Three organisms have been isolated from defective commercially-canned cream which, on inoculation into normal cream, cause bitterness and thinning.

2. These organisms are described and are shown to be strains ofB. subtilis.Their spores are capable of withstanding temperatures up to 120°C. for as long as 40 min.

3. The rate of development of bitterness and thinning in experimentally inoculated cans is shown to vary with the culture used and with the temperature of incubation.

4. Both bitterness and thinning are associated with the breakdown of protein, as indicated by determinations of the non-protein nitrogen and of the peptone and subpeptone fractions.

5. The alterations in viscosity do not appear to be due to any fundamental change in the structure of the cream, nor to differences in the degree of clumping of the fat globules.

6. The applications of the results in commercial practice are discussed.
174. The effect of commercial sterilization on the nutritive value of milk. IV. Effect on the vitamin B complex, on vitamin B1 and on vitamin B2 (flavin) of milk
Authors: Henry K. M. , Kon S. K.
Published: June 2009

1. The effect of commercial sterilization on the vitamin B complex, vitamin Bx and vitamin B2 (flavin) of milk has been investigated in experiments on rats using milk from the same bulk before and after heat treatment.

2. No quantitative comparisons were carried out regarding the vitamin B complex, but the tests showed that a considerable destruction of some component or components of it had been caused by the heat treatment and that vitamin B1 was, most probably, one of them.

3. Separate tests showed that about one-third of the vitamin B1 originally present in milk was destroyed by sterilization.

4. Sterilization appeared to have no adverse effect on vitamin B2 (flavin).
186. The casein number. A chemical method for diagnosis of mastitis
Authors: Rowland S. J. , Zein-El-Dine M.
Published: June 2009

The accuracy of the casern number of milk as the basis for a chemical method for the detection of mastitis has been investigated. The number was determined for 247 samples of milk from the individual quarters of sixty-two cows, and the samples were examined bacteriologically for mastitis streptococci. Of the 247 quarters 49% were found to be infected—mostly subclinically—involving 74 % of the cows.

The total nitrogen content of the samples varied from 362· to 687·4 mg. per 100 ml., and the casein nitrogen from 153·0 to 554·0. The casein number varied from 42·3 to 83·4. The casein number averaged 79·2, 80·4, 79·5 and 80·3 in the samples from the uninfected quarters of the Shorthorn, Friesian, Ayrshire and Guernsey cows respectively; and 71·7, 74·1 and 70·3 in the samples from the infected quarters of the Shorthorn, Friesian and Ayrshire breeds respectively.

For the diagnosis of mastitis from the casein number, a figure of 78·0 and less was taken as indicating an infected quarter, and on comparing this chemical method with the bacteriological method, out of a total of 243 quarters, the chemical result differed from the bacteriological for 21 quarters—representing 8·6 % of the total.

Reasons are given for considering that this estimate of the error is excessive and that in practice the casein number would provide a valuable and rehable method for the diagnosis of mastitis.
187. The effect of subclinical mastitis on the solids-not-fat content of milk
Authors: Rowland S. J. , Zein-El-Dine M.
Published: June 2009

The solids-not-fat content (expressed as a percentage of fat-free milk) has been determined for 247 samples of milk from the individual quarters of sixty-two cows. The samples were also examined bacteriologically for the presence of mastitis streptococci and 121 were found to be infected, 114 uninfected, and twelve “doubtful”.

The solids-not-fat content of the uninfected samples varied from 8·24 to 10·28 and of the infected samples from 4·26 to 9·92. For the uninfected samples of the Shorthorn, Friesian, Ayrshire and Guernsey breeds it averaged 9·36, 9·11, 9·82 and 9·83 respectively, but in the infected samples only 8·44, 8·38, 8·28 and 9·49%.

Of the 247 samples, 36 % were below 8·80 in solids-not-fat content. Of 121 infected samples, 63% were below while of the 114 uninfected samples only 9% were below this standard. Hence 88% of the samples below 8·80 were infected samples, thus showing that subclinical mastitis accounts for a very high percentage of samples low in solids-not-fat content. In these samples the average value for solids-not-fat was 7·93%. The few uninfected samples that were low in solids-not-fat averaged 8·56%.
194. The calcium and phosphorus contents of some types of British cheese at various stages during manufacture and ripening
Authors: Mattick E. C. V.
Published: June 2009

The loss of calcium and phosphorus at various stages in the manufacture and ripening of British hard pressed cheese (Cheddar, Cheshire, Leicester and Lancashire) has been followed. As all the cheese were made from portions of the same bulk milk the results are comparable.

It has been shown that there is remarkably little difference in the values of the hard pressed varieties, but that Stilton contains much less calcium and considerably less phosphorus than any of the other varieties examined.
199. The chloride content of milk
Authors: Davies W. L.
Published: June 2009

The frequency distribution of the chloride contents of 7802 samples of milk, grouped into morning and evening samples, monthly samples for three consecutive years from the Institute herd, samples from Shorthorn, Guernsey, Ayrshire and Friesian cows, and other miscellaneous samples, has been determined. The mode for morning milk is 81–90 and for evening milk 71–80 mg. %. The mode for Guernsey and Shorthorn milk is 71–80 and for all (6076) samples, 81–90 mg. %. The mode for milk from herds of Friesians known to give milk of low content of solids-not-fat was 111–120 mg. %, but this must not be taken as the value for this breed generally. The average for Shorthorn milk is 97, Guernsey 93, Institute herd 93, all samples 98, special Friesian herd 128 and bulk Institute milk 85 mg. %.

Factors influencing the chloride content of milk such as breed, age of cow, lactation period, number of lactations, seasonal effects, and udder troubles have been discussed from inspection and by deduction from the series of values obtained.

The electrical conductivity of milk increases with chloride content but there is some deviation from the linear law. The conductivity increases at a greater rate than the chloride content in samples high in chloride, probably owing to the increase in electrolytes other than chloride.
205. Methods of measuring gas production
Authors: Allen L. A.
Published: June 2009

Gas production in dairy products is a subject of considerable importance, since it is responsible for certain defects in milk, cream, cheese and occasionally condensed milk. Four groups of micro-organisms are concerned, namely, yeasts, lactic acid bacteria, coliform bacteria and spore-forming anaerobes, and of these the fixs two produce carbon dioxide only while the last two produce a mixture of carbon dioxide and hydrogen (with some anaerobes there may be methane as well). Where both gases are evolved the effectiveness of the two as regards ability to produce effervescence or to develop pressure in a closed container or in a hard-pressed substance like cheese differs by virtue of the fact that carbon dioxide is soluble in water (its solubility depending on the pressure and pH of the medium) while hydrogen is insoluble. Until the medium in which such micro-organisms are growing becomes saturated with carbon dioxide the effective gas production is therefore due to hydrogen. On the other hand, in some media the hydrogen may be involved in secondary reactions with some of the constituents while in the nascent condition and will therefore not form gas.
227. The rapid determination of peroxide values for the fat in milk powders
Authors: Smith J. A. B.
Published: June 2009

1. A rapid method for determining the peroxide value of the fat contained in whole milk powders is described.

2. As estimated by this method the peroxide value is only about 90% of the true value, but in many researches where the method would be applied, it is the relative rather than the absolute peroxide value which is required. Consequently the disadvantage of a slightly low estimation is far outweighed by the rapidity of the method and the ease and reliability with which it can be performed.
239. Examples of variation within pure cultures ofStreptococcus cremoris
Authors: Hunter G. J. E.
Published: June 2009

Indications of variability within pure strains of Str. cremoris have been studied.

In one strain changes in acid-producing power were made evident by changes in colony form. A variant which failed to ferment lactose but was still susceptible to the specific race of bacteriophage and exhibited the same morphology (after treatment at 37° C.) as the parent culture is described.

It was found that variation was well marked within some strains, especially in regard to acid production (or vitality), response to high temperature conditions, power to produce ropiness in milk, and degree of resistance to phage attack.
244. The vitamin A and carotene content of Shorthorn colostrum
Authors: Henry K. M. , Houston J. , Kon S. K.
Published: June 2009

1. The concentration of carotene and of vitamin A in colostrum and colostral fat and the total daily yield of these substances in successive milkings has been studied for four shorthorn cows and nine heifers.

2. The concentration of vitamin A in the first colostrum ranged from 8160 to 820 Moore blue units per 100 g. and that of carotene from 2026 to 411 Moore yellow units per 100 g.

3. The highest and lowest concentrations and yields of vitamin A and carotene respectively in samples of colostrum and later milk were in the ratios: per g. of colostrum (milk) 35:1 and 65:1; per g. of fat 27:1 and 34:1; calculated on daily yield 31:1 and 65:1. This last calculation favours colostrum.

4. Access to pasture before calving appeared to have no effect on the secretion of vitamin A in colostrum but increased the output of carotene.

Our best thanks are due to Mr A. G. Cotton who supervised the collection of the samples of colostrum and to Miss D. V. Dearden for churning the butters.
249. Studies on the methylene-blue reduction test II. Comparison between the old and the modified methods
Authors: Matuszewski T. , Supińska J.
Published: June 2009

In order to compare the old and the modified methods of the methyleneblue reduction test, 185 samples of raw milk were examined. We followed Wilson's method absolutely, but included two tubes in each test, one of which was inverted and the other not.

The results obtained and their interpretation agreed with the theoretical expectations given in our previous paper, and briefly outlined at the beginning of the present paper.

It is found that the deviations in the reduction time, corresponding to a given initial number of cells, are smaller by the modified than by the old method, and that the average time of reduction is shorter.

The smaller variation in the reduction time corresponding to a given number of cells at the beginning of the test is due probably to a more uniform distribution of the bacteria in the milk following the inversion of the tube. Wilson's suggestion that the shortening of the reduction time in the modified method is due to the stimulation of bacterial growth proves to be entirely correct. We obtained the average coefficients of multiplication in the old method of 0·660, and in the modified of 0·885.

Our results confirm on the whole the positive value of the modification of the methylene-blue reduction test as suggested and worked out by Wilson.
251. The action of chemical disinfectants on bacteriophages for the lactic streptococci
Authors: Hunter G. J. E. , Whitehead H. R.
Published: June 2009

The times needed for the complete inactivation of bacteriophages for the lactic streptococci by several chemical disinfectants in various strengths were determined. The phage preparations, consisting essentially of whey, contained the usual amounts of protein and lactose, so that the results obtained must be considered applicable only under the defined conditions. Hydrogen and hydroxyl ions were found to inactivate phage when they were present in sufficient concentration but their effects between pH. values of 4 and 7 were negligible over several days at room temperature.

By far the most effective of the disinfectants were active chlorine and permanganate, which suggests that the inactivation of phage is most readily brought about by oxidation.
263. The passage of carotenoids from food to milk in the cow. The fate of lycopene
Authors: Gillam A. E. , Kon S. K.
Published: June 2009

The question whether the tomato pigment, lycopene, an isomer of carotene, can pass from food into milk in the cow has been submitted to direct test by feeding three different cows with tomato purée and examining the resulting milk fats separately for lycopene. No evidence of the presence of lycopene has been detected in the unsaponifiable matter of the butter fat when this was subjected to careful chromatographic adsorption and it is concluded that, although the cow normally absorbs α- and β-carotene and certain oxidation products of these substances from its food it completely excludes the isomeric and very similar lycopene which has been found in the faeces in considerable quantity after tomato feeding. The mechanism of this selective absorption of one isomer only is quite obscure.

2. Adsorption of the carotenoids of several colostrum fats gave no indication of the presence of lycopene but the adsorption columns contained two small zones above that of β-carotene due to traces of pigments having absorption maxima at 452 and 425 mμ. (petroleum ether b.p. 70–80°). These may be due to oxidation products of β-carotene.
267. Studies on the chemistry of Cheddar cheesemaking VII. The measurement of the acidity of cheese and the relation of acidity to grading score
Authors: Dolby R. M. , McDowall F. H. , Riddet W.
Published: June 2009

The pH of cheese at 14 days old appears to be the most useful means of measuring the extent of acid development in the cheese, and shows a very fair agreement with the observations of graders on mature cheese. Cheese with a pH value close to 4°90 at 14 days gained the highest average score at maturity.

Measurements of titratable acidity either on the aqueous extract of the cheese or directly on a paste of the cheese, readily distinguish cheese which are insufficiently acid, but do not clearly distinguish over-acid cheese or cheese of low pH value: The direct method of acidity titration has the disadvantage that the results are affected to such an extent by the colour of the cheese as to make impossible the comparison of results on cheese of different colour intensities.

pH or titratable acidity values for mature cheese are less useful indicators of the quality of the mature cheese than the values at 14 days.
301. The effect of over-ripening upon the activity of Cheddar cheese starters
Authors: Johns C. K. , Bérard H. L.
Published: June 2009

The belief that over-ripening of starters is responsible for their weakening and for slow acid development during Cheddar cheese-making has been widely held by cheese-makers for many years. Statements that over-ripening is harmful have been made by investigators in several countries(1,2,3,4), but experimental evidence in support of this view is scanty. On the other hand, Whitehead(5) in New Zealand has shown that prolonged over-ripening of single-strain starters under rather extreme conditions merely resulted in a temporary checking of their activity; between wide limits of size of inoculum and period of incubation no permanent damage was done.
368. Deterioration on storage of dried skim milk
Authors: Henry Kathleen M. , Kon S. K. , Lea C. H. , White J. C. D.
Published: June 2009

1. Three spray-dried separated milk powders with moisture contents of 2·9, 4·7 and 7·3% (3 hr. air oven) or 3·0, 5·0 and 7·6% (20 hr. vacuum oven) were packed in air and in almost pure nitrogen, in gas-tight cans, and stored at 20·0, 28·5 and 37° C, for a period of nearly 2 years.

2. The powders were examined at intervals for palatability, colour, pH, equilibrium relative humidity (indicating crystallization of the lactose), conversion of β-lactose to α-lactose hydrate, decrease in total soluble lactose, absorption of oxygen, production of carbon dioxide, solubility in water at 20 and at 50 or 60° C, changes in the distribution of soluble nitrogen, reducing power towards potassium ferricyanide, base-binding capacity, formol titration, weight of the undialysable fraction, free amino-nitrogen by the Van Slyke method, sugar attached to the protein, and bacterial content.
383. Investigations on bovine mastitis.: 4. The association of new infections caused by Streptococcus agalactiae with (a) season and (b) stage of lactation
Authors: June Ineson P. , Cunningham A.
Published: June 2009

Regular testing at 3-monthly intervals for periods extending to 7 years of some 650 to 850 cows in fourteen herds indicated that the majority of the new infections caused by Sir. agalactiae were recorded in the autumn months, August, September and October.

When infections were considered in relation to the stage of lactation, although higher new infection values were recorded at the first test after calving than at later stages, the differences were not statistically significant.

We are indebted to Dr D. N. Lawley for advice on the statistical interpretation of the results of this investigation.

Acknowledgement is also made to the Agricultural Research Council for grants in aid of the investigation.
400. Factors influencing the keeping quality of ghee
Authors: Persai D. P. , Barnicoat C. R.
Published: June 2009

Of the four main factors commonly regarded as influencing keeping properties of ghee, viz. moisture content, acidity, heat treatment and type of bacterial culture used in souring, the heat treatment was found to be the most important.

In general, the higher the final temperature (110° C. and higher) attained during evaporation, the better were the keeping properties of the product, providing that the butter had been heated in contact with curd, boiled as rapidly as possible, and given a minimum amount of stirring.

The improved keeping properties conferred on ghee heated to 110–150° C. were promoted by antioxidants (apparently phospholipids) extracted from the curd during cooking.

Initial acidity and moisture contents had no effect on storage life of ghee at 38° C., and the practice of grading ghee according to its acidity would appear to be of questionable value. Souring of milk to give 2·5–3·0% lactic acid and the accompanying desirable flavour did not detract from the keeping quality of the ghee made from it.

The type of bacterial culture used for souring had only slight influence on keeping quality of ghee, but a marked influence on flavour.

Storage life of ghee at 38° C. (‘Indian summer temperature’) could be predicted with fair accuracy from its rate of oxidation at 100° C. in a ‘Swift oxidation tester’.
404. Determination of the solubility of roller-dried milk powder
Authors: Parsons A. T.
Published: June 2009

This note gives particulars of a method of determining the solubility of roller-dried milk powders which has been in use in the Department of the Government Chemist for some years. The figures obtained are empirical but are found to be a valuable aid in the comparative assessment of quality. The method is not claimed to be highly original, but appears to have aroused sufficient interest to justify publication. It is used in the Department for roller-dried milks only. For spray-dried powders a method is employed which measures the volume of deposit given on centrifuging similar to the Solubility Index test of the American Dry Milk Institute.
422. Cheese discoloration: oxidation of bixin in annatto-coloured cheeses promoted by sulphydryl compounds
Authors: Barnicoat C. R.
Published: June 2009

Some years ago discoloration was reported in mature New Zealand export cheeses. The defect occurred typically as bleached or pink areas surrounding cracks, though a less frequent ‘muddy’ discoloration was also noted. Discoloration was, on the whole, restricted to cheeses made in warm weather. Preliminary observations showed that the defect had certain characteristic features, viz.
455. The ripening of Stilton cheese: changes in the volatile acid content
Authors: Hiscox E. R. , Harrison J. , Wolf J. Z.
Published: June 2009

The changes in the volatile acidity and other factors during the ripening process of Stilton cheese have been studied. The growth of the mould was characterized by an increase in the fat-soluble fatty acids derived from the cheese fat.

Pricking the cheese ensured a more uniform blueing and hastened the ripening. There was no evidence that judicious pricking at 2 months after manufacture seriously affected the course of the ripening. Excessive pricking, however, produced abnormal cheese of poor keeping quality.
456. The calcium and phosphorus of Cheddar and Stilton cheese: I.Cheddar and Stilton cheese of normal manufacture: II. The distribution of calcium between the crumb and coat of Stilton cheese
Authors: Mattick E. C. V.
Published: June 2009

The loss of calcium and phosphorus during the manufacture of hard pressed (Cheddar) and impressed (Stilton) cheese made from the same bulk of milk has been studied. It is found that there is little loss of mineral salts from the hard pressed variety either after cutting the curd during making, or while the cheese is ripening. In the case of the unpressed variety there is constantly increasing percentage loss of minerals, correlated with an increase of titratable acidity in the whey, until the last stages of manufacture when the cheese are removed from the hoops for scraping.

The figures confirm those previously found (i) that in the cheese examined 57–58% of the calcium and 50–51% of the phosphorus present in the milk originally used, remains in the hard pressed ripe cheese, but that only 6–8 % of the calcium and 27 % of the phosphorus are left in the unpressed variety when ripe.
499. The inhibition of micro-organisms by raw milk: I. The occurrence of inhibitory and stimulatory phenomena. Methods of estimation
Authors: Auclair J. E. , Hirsch A.
Published: June 2009

1. A diffusion cup technique using Micrococcus lysodeikticus has been found suitable for lysozyme estimation. By this method raw milk gave only small zones of inhibition. The inhibitory substance of milk was shown not to be lysozyme.

2. Dose-response curves (dilution v. pH) were obtained with Streptococcus pyogenes as the test organism. They indicated that the effect of milk on this organism was the result of the interaction of one stimulatory and at least two inhibitory substances.

3. The existence of two inhibitory substances was confirmed by dilution assays, one, L1, occurring mainly in colostrum, the other, L2, occurring mainly in milk. The inhibition is greatest when L1 and L2 act simultaneously.

4. The pH and heat stabilities of the two substances are slightly different. L1 is most stable at pH 6−6·5, 90% being destroyed at 68° C. L2 is most stable at pH 7 and 95% is destroyed at 74°C.
505. The accuracy of measurements of the mammary glands by the method of palpation
Authors: Sheppard D
Published: June 2009

1. An investigation was carried out, using objectively measurable stimuli, to examine the method of assessing the size of the mammary glands of calves by palpation. The method was that described by Swett.

2. The results indicate that the estimated sizes may be very different from the true sizes, although the two are generally highly correlated. In most cases the estimated sizes are significantly smaller than the true sizes.

3. Different judges give very different estimated sizes for the same true sizes, thus it is not justifiable to compare directly glands which have been stated to be of the same size by different judges.
523. A note on the electrical resistance and the keeping quality of butter
Authors: Prentice J. H.
Published: June 2009

During the course of some earlier work (not yet published) on the physical properties and the quality of butter, the writer noticed that occasionally a sample was encountered which appeared to be very slightly rancid after only 3 weeks' storage in a cold store. These samples were observed to have a low electrical resistance, and to be of inferior texture, usually exhibiting some free moisture droplets when freshly cut. It appeared likely that there might be some definite relation between the resistance, the texture, and the keeping quality of butter. At the time of these experiments, however, the phenomenon only occurred with a few samples of one type of blended butter. The present note describes an experiment designed to explore the possibility that the relationship might be more general, and apply to other types of butter.
529. Pulsation and milking rate
Authors: Clough P. A. , Dodd F. H. , Hughes E. W.
Published: June 2009

The pulsator mechanism of the double-action milking machine causes the rhythmical expansion and collapse of the rubber teat-cup liner during milking by alternately applying a partial vacuum (usually 13–15 in. Hg) and admitting atmospheric air to the space between the rubber liner and the teat-cup shell. The inside of the liner is subjected to continuous partial vacuum.
536. The physical properties of cow's milk as influenced by stage of lactation: The Size Distribution of Butterfat Globules
Authors: Whittlestone W. G.
Published: June 2009

An examination of the fat-globule size distribution pattern has been made throughout the lactation for one quarter of one cow, samples being taken at different stages in the milking process using a normal milking machine with sampling device attached.
541. A note on the vitamin D content of Indian butters
Authors: Henry K. M. , Kon S. K.
Published: June 2009

1. The vitamin D potency of three samples of south Indian butter has been determined in prophylactic tests with rats.

2. Two samples of butter from Bangalore contained 0·56 and 0·41 i.u. vitamin D/g. fat, a sample from Coimbatore contained 0·29 i.u./g. fat.
617. Variations in the carotene and vitamin A contents of herd butterfats throughout lactation
Authors: McDowell A. K. R.
Published: June 2009

The carotene and vitamin A contents of the butterfat from the milk yielded by the cow in early lactation may be higher than normal for a period of up to 10 or 12 days after parturition.

Seasonal changes in carotene content of butterfat from small herds of cows were governed almost entirely by the availability of carotene in the pasture and not by lactational influences.

Seasonal changes in vitamin A content of the herd butterfats were relatively small during most or all of the lactational period. In certain years an increase in the vitamin A content during the autumn months was probably due to seasonal conditions and not to a lactational effect.
624. Udder infections in the ‘dry period’: II. The effect of withdrawing secretion from the dry udder on the incidence of infection
Authors: Oliver J. , Dodd F. H. , Neave F. K. , Lee J. M.
Published: June 2009

1. An experiment was carried out with seventy-five dry cows to study the effect of taking samples of udder secretion for bacteriological examination on the incidence of new infection in the early dry period. The incidence of new infection in two quarters of each cow, sampled at weekly intervals after drying off, was compared with that in the remaining two quarters sampled in the fourth and fifth week of the dry period.

2. No difference in the new infection rates was found between the quarters that were sampled early in the dry period and those that were not.

3. Significantly fewer (P <0·05) staphylococcus infections occurred in quarters sampled in the early dry period compared with those sampled at a later stage.

4. About half of all the new infections persisted until the next lactation.

5. It was concluded that if natural sealing of the teat orifice or teat sinus takes place it is of minor importance in preventing infection in the early dry period.
634. The determination of the coagulating power of commercial rennet extracts using an automatic tester
Authors: Storrs F. C.
Published: June 2009

1. A method for preparing rennet reference standards by freeze-drying is described.

2. A substrate has also been developed using ordinary spray dried separated milk powder which will give reproducible results under specified conditions. These include:

(i) A constant temperature (37° C.) for the duration of the test.

(ii) The exclusion of added calcium ions until actual testing begins.

(iii) The equilibration of the milk at 37° C. for 2 hr. before use.

3. The construction and use of an automatic apparatus for recording rennet coagulation time is also described.

4. The instrument error of a single observation is about 1·0%.

5. With liquid rennet extracts, the total experimental error, based on one sample of three replicates, is 2% or less: with two samples, it is 1% or less.

6. With freeze-dried rennet preparations, the experimental error with two ampoules, sampled thrice with three replicates per sample, was ±2·.0%. With three ampoules it was ±1% or less.
663. The relationship between milk secretion and the rate of milking by machine
Authors: Clough P. A. , Dodd F. H.
Published: June 2009

Lactation has two phases: the continuous process of secretion and the mechanism of ejection which occurs only during milking. Because ejection is a transitory phase it is to be expected that within certain limits milk yield will be inversely related to the duration of milking, which was, in fact, demonstrated many years ago with hand-milked cows(1). With machine milking the situation is different because the forces which the machine applies to the udders of all cows within a herd are the same, and thus the differences in milking rate that occur are due to differences between the cows. Under these conditions, if milking rate can be shown to affect milk yield it is a demonstration of how the physiological factors controlling milking rate can modify the expression of the inheritance of milk secretion.
676. Diffuse reflexion spectra of dairy products in the near infra-red region
Authors: Goulden J. D. S.
Published: June 2009

A method for the study of the diffuse reflexion spectra of dairy products in the near infrared region has been described. It has been shown that in this region of the spectrum, the reflexion method gives better results than the transmission method for butter and dried milk products. The effects of homogenization on milk spectra have been studied, and also the effects of temperature and mechanical working on the spectrum of butter have been considered. Assignments have been made for the bands observed in the dried milk spectra and the effects of moisture and other factors on the spectra of dried materials have been briefly studied.
705. A comparison of dried skim-milk and white fish meal as protein supplements for fattening pigs: II. On all-meal feeding under commercial conditions
Authors: Braude R. , Clarke Pamela M. , Mitchell K. G. , Cray A. S. , Franke A. , Sedgwick P. H.
Published: June 2009

1. Results are reported of an experiment carried out under commercial conditions to obtain information on the comparative value of dried skim-milk and white fish meal as protein supplements for fattening pigs.

2. There were four treatments. Control pigs (i) received a meal mixture containing 10% white fish meal, reduced to 7% from 130 lb. live weight. In the other experimental groups, the fish meal was replaced by dried skim-milk, (ii) on a weight for weight basis, (iv) on a protein basis and (iii) intermediate between (ii) and (iv). All pigs were fed the meal dry and ad lib. up to a maximum of 6½ lb./head daily. Unrestricted water was available.

There were five pens of nine group-fed pigs on each treatment, involving a total of 180 pigs. The pigs were on experiment from approximately 10 weeks of age to bacon weight. Comprehensive carcass measurements were made on all the pigs.

3. The results showed that a significantly better rate of growth was obtained when the white fish meal was replaced by dried skim-milk on a weight for weight basis. Increasing the percentage of skim-milk in the diet up to 15% resulted in a slightly better performance of the pigs, but no further improvement was obtained by raising the level of skim-milk to 20%. These results were discussed in relation to an apparent set-back that the control pigs suffered at the start of the experimental period.

4. The inclusion of dried skim-milk in the diet had an adverse effect on the carcass grading, particularly in so far as it resulted in a thicker layer of back fat over the loin as compared with that in the control pigs.

5. There was also some indication that the carcasses from the animals given dried skim-milk had slightly thicker bellies and a smaller breadth of eye muscle than the carcasses of the control animals that received fish meal.

6. The results have been compared with those of an earlier trial, which was in most details the same as that reported here, the main difference being that in the earlier experiment individual feeding and one breed of pig were used.
707. Phospholipids in New Zealand dairy products: I. The estimation of the total phospholipids and of lecithin, cephalin and sphingomyelin in butter
Authors: McDowell A. K. R.
Published: June 2009

A method has been described for the routine estimation of total phospholipids and of lecithin, cephalin and sphingomyelin in butter. Butter serum was treated with ether and light petroleum in a modified Röse-Gottlieb procedure to extract the phospholipids which then were estimated in the extract.

Chloroform-methanol extracted from the butter serum slightly more phosphorus than did the ether-light petroleum mixture. Ethanol-ether, benzene-ethanol and benzene-isopropanol, when used to extract a protein-phospholipid precipitate formed by the addition of trichloroacetic acid to butter serum, also removed slightly more phosphorus than did the ether-light petroleum mixture. The higher phosphorus contents of these extracts was due partly to a slightly more efficient extraction of phospholipids and partly to extraction of non-phospholipid phosphorus compounds.
717. Physical changes in milk caused by the action of rennet: II. Heats of reaction
Authors: Phipps L. W.
Published: June 2009

The rennet-catalysed coagulation of milk casein has been examined calorimetrically. The heat of coagulation and syneresis was found to be less than 0·1 cal.'40 ml. of milk, the limiting sensitivity of the apparatus.

Heats of reaction approaching 0·5 cal. were observed when the milk was acted upon by the enzymes trypsin and papain. It is doubtful whether, at this stage, the results can be correlated with the several phases of the reaction.
720. A rapid optical test for homogenizer efficiency
Authors: Goulden J. D. S.
Published: June 2009

It has been shown that the degree of homogenization can be tested directly by measuring the transmission of milk samples of thickness ca. 0·1 mm., using wavelengths in the near infra-red region.
Steam distillation of taints from cream: VI. Butterfat/lactose-solution distribution coefficients of some reference substances
Authors: McDowall F. H.
Published: June 2009

1. Coefficients of distribution for acetoin, diacetyl and acetylpropionyl between butterfat and skim-milk were measured over a range of temperatures up to 190° F. by passing preheated milk containing the reference substance through an hermetic cream separator and analysing the cream and skim-milk obtained.

2. The coefficients increased with rise in temperature, and the relationship between change in coefficient and change in temperature was linear for all three substances.

3. Coefficients of distribution for acetyl-iso-butyryl, acetylvaleryl, acetylcaproyl and acetylbenzoyl between butterfat and 4·5% lactose solution were measured at 40° and 60° C. by direct separation after equilibration, followed by estimation of the diketone in the lactose solution.

4. Coefficients of distribution at 100° C., obtained by linear extrapolation from these results, were: acetoin, 0·255; diacetyl, 1·27; acetylpropionyl, 5·9; acetyl-iso-butyryl, 20; acetylvaleryl, 23; acetylcaproyl, 152; acetylbenzoyl, 48.

5. The coefficients of distribution for diacetyl and acetylpropionyl between butterfat and 4·5% lactose solution were not affected by change in concentration of the diketone in the lactose solution.
Physical changes in milk caused by the action of rennet: IV. Effects of varying rennet concentration and temperature.
Authors: Blair G. W. Scott , Burnett J.
Published: June 2009

1. Under carefully standardized conditions, the increase in the over-all rigidity modulus of curd when the time after rennetting is doubled, varies inversely as the cube root of the rennet concentration. The intercepts of the extrapolated setting curves on the time axis and the observed coagulation times vary inversely as the concentration.

2. With the same (normal) rennet concentration, some rheological parameters increase or decrease progressively as temperature is increased from 21° to 41° C.; others pass through maxima or minima, all between 29° and 35° C.

3. Long-term ‘creep’ experiments have been done over the above temperature range, creep and slow recovery increasing progressively with temperature. Relaxation experiments, though showing the simplest distribution of relaxation times at about 32° C., are too greatly influenced by unavoidable differences in firmness at the different temperatures for it to be possible, at this stage, to draw conclusions about their temperature dependence.

4. A comparison of some of these results with data published by a few other workers is attempted.
Isolation and identification of the high molecular weight saturated fatty acids of butterfat
Authors: Hansen R. P. , Shorland F. B. , Cooke N. June
Published: June 2009

Butterfat has been shown to contain thenormalodd-numbered saturated acidsn-nonadecanoic acid (C19),n-heneicosanoic acid (C21), andn-tricosanoic acids (C23).

The presence of the normaleven-numbered acidsn-octadecanoic acid (C18),n-docosanoic acid (C22),n-tetracosanoic acid (C24) andn-hexacosanoic acid (C26) is conclusively established.

n-Eicosanoic acid (C20) formerly assumed to be present in butterfat has been isolated and identified by its physical and chemical properties.
Chemical changes in dried skim-milk during storage
Authors: Richards E. L. , Chandrasekhara M. R.
Published: June 2009

Dried skim-milk stored at 55°C in air at 70% relative humidity has been found to contain lactulose, galactose, tagatose, glyceraldehyde and maltol; and formic, acetic and glycollic acids. These compounds are not present, or are present only in trace quantities, in fresh dried skim-milk. It is suggested that while the proteinsugar reaction is responsible for most of the browning of the powder, many of the compounds found are formed by degradation of lactose catalysed by the free basic amino groups of the casein. The compounds so formed probably then react with amino groups in a Maillard reaction and thus contribute to the browning of the milk powder.
Studies on the manufacture of sweet cream starter butter: I. Effect of cream-holding temperature
Authors: McDowall F. H. , Singleton J. A. , Le Heron B. S.
Published: June 2009

Batches of cream inoculated with 1% of a culture of Streptococcus diacetilactis or of one or other of two mixed starters were held at different temperatures over the range 37–57°F before churning. Diacetyl and acetoin were estimated in the creams at churning and in the butters fresh and after storage.

The diacetyl production of all three starters in the cream increased with increase in temperature, although at the lower temperatures there was no indication of any rise in titratable acidity. At 52 and 57°F there was some rise in acidity during the holding period.

The butters were of good keeping quality. There was a small but definite reduction in the diacetyl content of the butters during storage, but the extent of the change was not related to the holding temperature of the creams.

It was concluded that if sweet cream starter butter is to be made with uniform intensity of flavour the proportion of starter added must be adjusted to counterbalance changes in the cream-holding temperature.
Studies on the manufacture of sweet cream starter butter: II. Effect of variation in proportion of starter added to cream
Authors: McDowall F. H. , Singleton J. A. , Le Heron B. S.
Published: June 2009

Production of diacetyl and acetoin by starters in cold skim-milk and cream was shown to increase with increase in the proportion of starter culture added, with some limitations at the higher rates of starter addition.

With Streptococcus diacetilactis starter in skim-milk at 50°F the relation between proportion of starter added and production of diacetyl was linear up to addition at the 4% level, whereas at 43°F it was approximately linear up to the 10% level. At both 50 and 43°F the relation between the proportion of starter added and the production of acetoin was linear up to the 10% level.

With Camb starter in skim-milk at both 50 and 43°F there were regular increases in production of diacetyl up to the 4% level of addition, but only minor changes thereafter with increase in the proportion of starter added up to 10%. At both temperatures the maximum production of acetoin was reached with the 7% rate of addition.

Production of diacetyl and acetoin in skim-milk was greater at 50°F than at 43°F with both starters for all proportions up to 10%, and it was greater for Str. diacetilactis than for the mixed cultures.

Except at the higher rates of addition of starter and at the higher temperature there were no concomitant increases in the acidity of the milk or lowering of the pH values. It appears that at low temperatures production of diacetyl by starters in sweet milk and cream proceeds independently of production of lactic acid.

Similar results were obtained in a series of experimental buttermaking trials and some small commercial-scale trials, in which varying proportions of starter were added to creams after pasteurizing and before holding overnight for churning. With the cream-holding temperatures used, mainly 40–50°F, the pH values of the butters were not appreciably lowered by the starter additions to the cream. At all the rates of addition there were with Str. diacetilactis starter higher contents of diacetyl in the butter than with Camb starter. There was no indication of any relationship between the proportion of starter added and the keeping quality of the butter.
A comparison of biochemical and paper chromatographic methods for the identification of group D Streptococci from Cheddar cheese
Authors: Steenson T. I. , Robertson P. S.
Published: June 2009

Forty-four strains of tributyrolytic group D streptococci isolated from Cheddar cheese were identified by physiological, biochemical and serological tests. They were also independently grouped using two-way paper chromatography in which patterns of ninhydrin positive spots were developed from 10% acetic acid extracts of the bacteria. The groupings obtained by the chromatographic and conventional techniques were then compared. Strains of Str. durans were well differentiated by chromatography from the other species of group D streptococci examined, but with the remainder less clear differentiation was obtained.
A note on a method of overcoming the effect of udder disease or injury in experiments involving milk yield and composition
Authors: Waite R.
Published: June 2009

In experiments to determine the effect of feeding changes on milk yield and composition, udder disease or injury may easily invalidate the results, particularly those for milk composition. It is suggested that regular examination of the milk from each quarter of the udder would allow a diseased or injured quarter to be recognized and a true value for the effect of the feeding treatment to be obtained from the composition of the milk from at least two healthy quarters. Examples to illustrate the suggestion are given.