AGRIC. LfBRARY Digitized by the Internet Archive in 2007 with funding from Microsoft Corporation http://www.archive.org/details/dairyfactorypremOOmacirich DEPARTMENT OE AGKKULTURE, NEW SOUTH WALES. SCIENCE BULLETIN, March, 1921. No. 20. Dairy Faciei ^Premises and Manufacturing Processes: The Application of Scientific Methods to their Examination. L. T. MaclNNES, Dairy Expert, and H. H. RANDELL Assistant to Biologist. Workers in the respective branches of Economic Science covered by this series of Science Bulletins will receive such of mem as may be of use in their special branches of study upon application to the Under Secretary and Director, Department of Agriculture, Sydney. SYDNEY: WILLIAM APPLEGAYE GULLICK, GOVERNMENT PHI NYER-— 1921. No. of Copies Issued, 1,200. DEPARTMENT OF AGRICULTURE, NEW SOUTH WALES. SCIENCE BULLETIN, No. 20. Dairy Factory Premises and Manufacturing Processes: The Application of Scientific Methods to their Examination. L. T. MacINNES, Dairy Expert, and H H. RANDELL, Assistant to Biologist. SYDNEY: WILLIAM APPLEGATE GULLICK, GOVERNMENT PRINTER. 1921. f 23J3-A Department of Agriculture, NEW SOUTH WALES. SCIENCE BULLETIN, No. 20. Dairy Factory Premises and Manufacturing Processes : The Application of Scientific Methods to their Examination. The manufacturer of dairy produce has always some trouble to contend with, for milk and its products lend themselves to rapid deterioration, especially through bacterial agencies. It was with a view to minimising such troubles — by presenting to those engaged in the industry such information as might be gained from scientific and practical investigations on the spot — that the scheme of examining butter factories and the manufac- turing processes carried out therein was initiated and approval obtained for the services of an officer of the Biological Branch of the Department of Agriculture to be placed at the disposal of the Dairy Branch. Apart from the ordinary every-day things that are always awaiting solution, we have what might be' classed as seasonal epidemics, such, for instance, as the mould infection with which a great many factory managers had to contend some two summers ago, and the effects now being felt of an extremely dry season. These influences need special inquiry as they arise. The present series of investigations, however, does not specially deal with these epidemic troubles, but is confined to those that form part of the daily routine of certain factories inspected. In the first case to be dealt with we have effects arising out of old and faulty premises badly situated from a sanitary point of view ; in other cases it had been noted that the choicest brand of butter marketed showed deterioration, more or less marked, whenever it was held in cold storage for any considerable length of time. The causes of this deterioration in quality have been traced by means of our investigations, and satisfactory remedial measures taken. As it is intended to commence this series of articles with the results obtained from an old bacterially contaminated factory, it is considered advisable to end it by way of contrast with those from one of the most modern — a factory built on the latest sanitary lines, where fresh air and sunlight have been recognised as the greatest of germicides and freely admitted accordingly. SCIENCE BULLETIN, No. 20. Some ten years ago the Alstonville Co operative Dairy Company had trouble with the quality of the butter then being manufactured, and an officer of the Dairy Branch investigated the matter and successfully used atmospherically exposed plates to trace the origin of the infection causing the deterioration, thereby enabling the company to remedy the matter. Knowing the value of arriving at and locating causes of deterioration by means of bacteriology, a scheme was worked out early last vear whereby whatever came in contact with the dairy produce after its arrival at the factory until it was placed on the market, could be systematically examined and the results compared. The general adoption by the New South Wales dairy companies of the practice of pasteurising cream made the initiation of such investigations the more opportune. The object aimed at was twofold : (a) To demonstrate the efficiency of pasteurisation as carried out' at certain factories. (b) To demonstrate whether or not the product was recontaminated after pasteurisation, and if so, how the infection took place. The methods followed were very similar in all cases and were carried out as follows : — 1. Samples were taken of the cream on arrival at the factory, after blending in bulk. y * 2. The same lot of cream, after being neutralised and pasteurised by either the "flash" or the "holding" system as it came from the outlet pipe of the " flash " or (in the case of the holding system) direct from the tank, was again sampled. In both cases these samples were obtained before the cooling process commenced. " 3. In the case of the flash pasteurisation, the plates were exposed 1\ minutes, and' in one case (Example 1) five minutes to the air over the pipe cooler used first to reduce the temperature of the cream. 4. Plates were atmospherically exposed for fifteen minutes over the cream-receiving and neutralising vat in the case of Example 1 to demonstrate the extent of infection from the water spray tower ; in other cases this was not done. 5. Where vats were used for holding cream (after passing over pipe coolers) pending churning, the tops of such vats being open, another series of plates were exposed to the atmosphere— for 2\ minutes in one case (Example 2) and five minutes in another (Example 1). 6. The same cream was again sampled as it came from the holding vats to enter the churns. 7. A sample was taken of the water used for cleansing and rinsing the churns and utensils. 8. A sample was taken of the water used to bring butter to the breaking point and; thereafter used to wash the butter. 9. A sample was taken of the butter made from the aforementioned cream as »t came from the churn. 10 Plates were generally atmospherically exposed in the churn room 2^ minutes, but in one case (Example 1) for five minutes, in all cases where the butter (or cream as it gravitated along the fluming from vat to churn) was exposed to the air. 11. A sample of the surface of the butter was taken from a box when packed and ready to be lidded. In conjunction with making these bacteriological examinations, the produce was graded for quality at all stages, thus :— (a) Cream on arrival at factory. (b) Cream after treatment when ready to churn. (c) Butter soon after being manufactured. DAIRY FACTORY PREMISES. 5 Some delay occurred in the earlier stages of the work, but eventually with the co-operation of the Biologist, Dr. G. P. Darnell-Smitb, another start was made early in October, 1919, and the results of the first portions of the investigation are now available. The Dairy and Biological Branches of the Department have approached the work in a spirit of co-operation for the benefit of the dairy industry. The Biological Branch was responsible for the bacteriological results, making the plates, isolating, identifying and counting the various colonies. The Dairy Branch, apart from initiating the scheme, supervised its operations up to the laboratory stage, correlating each step taken so that a comparison of the results might be jointly made and the information applied to the manufacture of dairy produce in a practical manner. De- ductions will be made from the data brought to light, and recommendations given as to how the dairy companies can best use them to retain and further enhance the reputation already achieved for the output of their factories. Example 1. This factory was built of wood many years ago, renovated to a certain extent about 1910 or 1911, and situated on the bank of a river with a lagoon at the back ; the water in the lagoon contained vegetation, was stagnant and heavily charged with germ life. This water was used to pump over the condenser of the refrigerating plant, and gave off a very apparent musty, swampy smell. The surroundings of the factory generally were unsatisfactory, and the inside premises were in a state of disrepair, floors, drains and walls needing attention. Leading from the front verandah (connected with the churn room by large double doors) were two underground earthenware 6-inch drains ; these pipes were straight, no bend or sanitary trap being inserted at the factory end. They emptied into a concrete well or sump and carried off all the washings of the churns and factory generally; at the time oc our visit a most offensive smell was arising from them and penetrating to all parts of the factory. "When the sump was half empty the outlets of the pipes were exposed and a draught of foul air blew right through them into the churn room. As was to be expected, butter made under such conditions was of inferior quality and showed further rapid deterioration when kept. It was arranged to make an inspection of the premises by bacteriological means, in addition to the outward examination of the premises and surroundings. Samples were taken of the cream, butter and water during the different processes of manufacture, and atmospheric exposures were made as already outlined. A room was given for use as a temporary laboratory, and in five days after our arrival the company's directors and manager were called in and shown the plates. These were explained and the company's representatives then taken through the premises and shown where the infections came from. As far as we know, this is the first time that dairy factory buildings have been scientifically inspected in this manner, and the result has been, from the Department's point of view, satisfactory. There is no disputing the results when obtained SCIENCE BULLETIN, No. 20. in such a manner — the ocular evidence is irrefutable and the Inspector's position vastly strengthened. Moreover, the directors of a company are able to prove to their shareholders how the deterioration in the quality of their factory's produce and the financial loss thus brought about takes place. Such a loss would be cut out and recovered by the building of a new factory, situated in a more convenient and sanitary position, on up-to-date lines. The cost of building and equipping at the present time may seem hard to bear, but the ultimate cost is less than the loss, year in and year out, of several shillings per cwt. on the selling price of the butter manufactured. Lifting the quality of- the butter by a few points means obtaining bigger returns. Take, for instance, a factory with an output of 35 tons of butter per week. If an extra 3s. per cwt. is obtained, it means over £100 per week extra revenue, and it does not take many years at that rate to pay for a modern, well-equipped factory. This lesson has been proved and demonstrated by the Manning River Co-operative Dairy Company. The quality of the butter now put on the market by that company is so improved as to be incomparable with that manufactured under the old conditions. It was proved at the same time that a saving of some £14 per week in labour was effected. In the modern, well-equipped factory nine men, working ordinary time, handled a much greater output than was done under the old conditions with thirteen men, often earning overtime rates of pay. The manufacture of butter may be described as a fermentative industry, the flavour being due co the absorption by the fat of certain aromatic substances produced during the acid fermentation of the lactose of the milk or cream by Bacterium lactis acidi and related organisms. Most of the abnormal flavours are due to the replacement of the desirable acid-forming bacteria with other types of micro-organisms. Hence, to control the flavour of the butter the butter-maker must control the bacteria in the cream that cause the ripening. As it is freshly drawn from the normal udder of the healthy cow, milk contains bacteria in greater or lesser numbers, the initial contamination taking place in the milk cistern and larger milk ducts of the udder. These organisms appear to cause no change in the market value of the milk, or in the persons drinking the milk. If, however, the cow is suffering from disease in the udder, such as tuberculosis, mammitis or other inflammatory trouble, the milk may contain many millions of the specific bacteria at the time when it is drawn. The extent of all subsequent contamination is dependent upon the manner and care with which the milk is produced and handled. The atmosphere, utensils, milking machines, and the milkers themselves add many bacteria ; their future development is largely dependent upon the temperature at which the milk is kept. Most micro-organisms find in milk an ideal culture medium for their growth. The food elements such as protein and milk sugar, being in liquid form, are most easily attacked, and it is the breaking down of these, by bacterial enzymes formed, which cause most of the undesirable changes DAIRY FACTORY PREMISES. The cream of milk, whether separated by gravity or by means of the separator, will contain considerably more bacteria per unit volume than the milk. The tiny fat globules passing through the milk serum carry mechanically many bacteria of the milk into the cream, which on arrival at the butter factory and often only a few hours old, is in many cases badly contaminated with bacteria. Experience teaches that such con- tamination can be avoided by efficient pasteurisation (and, if necessary, by neutralisation of excessive acidity) combined with the after-use of a pure culture starter. At the several butter factories visited, all samples were collected with sterile instruments and placed in sterile vessels, and the plating was carried out within half an hour of collecting the samples. In the case of example No. 1, an upstairs room in the factory was selected as the most suitable of those available, and although the conditions were not comparable with those of the laboratory, every precaution was taken to prevent undue contamination. The poured plates, with suitable dilutions of the various samples, were kept at 30 deg. Cent, for four days, when counting of the bacterial colonies was commenced, and the organisms were isolated in pure culture and classified according to their action on litmus milk, gelatin, glucose and lactose broth. Smear preparations from the different colonies were stained by Gram's method for microscopic examination. The media used for plating were ordinary agar, glucose agar, litmus lactose agar, an acid agar specially suitable for the develop- ment of moulds, yeast, the time the plates were exposed. The attemperator vats were placed in an adjoining room of much larger size, but also with low ceiling These vats were immediately over the churns. The cream examined was received in good condition and was closely graded by the Department's officers, and found to be of choicest quality. It will be seen from the plate Bl that much latent infection was present. The great number of organisms of the coli group demonstrate contamination at the cow-yard and bails ; other types present indicate that the cows had in some cases access to swampy ground and pools of stagnant water. In B2 it is shown that heating to 182 degrees Fah. practically sterilised the cream and made it possible to manufacture from it a high-grade, good keeping butter, thus proving that extreme care had been exercised in efficiently carrying out pasteurisation. Untreated in this way, such cream would make a butter that would deteriorate to a very low quality within a week. This care, with all the work and expense attached to it, was largely taken in vain, because of the practice (already referred to) of adding unpasteurised cream as a " starter " (see B3), the sharp acid flavour of w^hich covered up similar latent pollution to that previously destroyed in the bulk of the cream by the pasteurising process. This infection wras found in the butter when marketed, and was mainly responsible for reducing its grade, when made, from 43 points for flavour (choicest quality) to 38 points (or second grade and unfit for table use), some six weeks afterwards. In the interval this butter was kept in cold storage at 10 degrees Fah. 18 SCIENCE BULLETIN, No. 20. It will be seen from plate B5 that the water used for washing the butter contained liquefiers, gas formers and moulds. This water could be made, much better by being thoroughly filtered — for example, through cotton wool or felt pads. Filtering is especially necessary where, as in the present case, the watercourse is accessible to stock which wade in it' when drinking, and open for surface infections lying about the surrounding watershed to be washed into it by rains. Table II. — Showing Numbers and Kinds of Micro-organisms found in 1 Gram (1 c.c.)bf the following samples. - Total Micro- * organisms. Gelatin Liquefiers and Casein Digesters. Acid and Acid Coagu- lating. Acid and Gas Formers. Alkaline and Inert. Yeasts. Moulds. (Bl) Cream before pasteurising. . (B2) Cream immediately after pasteurising (B3) Cream 20 hours after pasteurising and immediately before churning (B4) Butter in box after packing B5) Butter-wash water 108,355,000 14,480 20,448,0(0 4,246,100 22,800 No oid 30,000 120,000 33,100 8,800 uims were pr 107,000,000 14,480 20,000,000 4,200,000 5,200 esent. 1,312,000 116,000 1,000 6,400 6,000 200,000 3,000 1,400 5,000 10,000 7,000 2,000 2,000 2,000 1,000 Sample Bl — Cream before Pasteurising. — The sample for plating was collected from the bulk in the cream-receiving vat by means of a sterile pipette. Each can of this cream had been graded choicest quality, then thoroughly mixed in the cream-receiving vat of 300 gallons capacity. The acidity was determined at 0-41 per cent, lactic acid. From the plates it is shown that 1 c.c. of cream contained 108,355,000 micro-organisms, in which Bact. Jactis acidi a desirable type, was the predominant organism. There were also present 30,000 peptonising bacteria including varieties of micrococci, sarcina, clada- thrix and Bact. fluoresceins liquefaciens, and 1,312,000 organisms of the coli group or undesirable lactose fermenters. Their presence in such large numbers is undoubted evidence of heavy pollution by faecal contamination. Among the acid and acid coagulating bacteria were 7,000,000 streptococci, the cells being oval and in long chains. Although these organisms coagulate milk, on account of their resemblance to a pathogenic variety they are regarded as undesirable. There were 6,000 chromogenic micrococci which made litmus milk alkaline but were unable to liquefy gelatin ; these may be classed as inert. Some 5,000 colonies of yeast were counted, while the 2,000 mould growths were Penicillium sp. Sample B'2 — Cream immediately after Pasteurising. — The sample for plating was collected by means of a sterile pipette immediately after being discharged from the outlet pipe of the pasteuriser. The cream had been neutralised to 0*24 per cent, acidity with lime and pasteurised by means of the flash system, where a temperature of 182 degrees Fah. was reached for a few seconds ; then cooled to 54 degrees Fah. by passing over pipe-coolers. It will be seen from the figures in Table II that 108,355,000 micro-organism DAIRY FACTORY PREMISES. 19 in 1 c.c. of the cream were reduced by pasteurisation to 14,480; of these none were able to liquefy gelatin. litmus milk was slowly made acid and eventually coagulated. The organisms were all rod forms, growth on all media being slow ; stained preparations from old cultures showed meta- chromatic granules, but spores were not found. Sample B3 — Cream immediately prior to Churning. — The cream after being pasteurised and pumped over the pipe-coolers was run into attem- perator or holding vats, where it was left overnight at 57 degrees Fah. Selected cans of cream were added as ''starter." These cans were chosen on account of the clean acid flavour of the cream. While this desired acid flavour would be caused by Bact. lactis acidi, a harmless and necessary type, it is evident that the conditions which allowed the entry and development of this desirable organism would also be favourable for the entry into the milk and cream of many undesirable types. The plates clearly indicate this, as it was ascertained that 1 c.c. of the cream contained 20,448,000 micro- organisms. Although 20,000,000 of these were "lactios," or desirable lactose fermenters, there were also 448,000 per c.c. of undesirable organisms, comprising 116,000 undesirable lactose fermenters or organisms of the coli group, 100,000 of the proteus group (a putrefactive type), 20,000 Sareina lutea, 10,000 yeasts, and 2,000 moulds. There were also counted 200,000 bacteria, which were unable to liquefy gelatin, and which, when inoculated into litmus milk, caused alkalinity or no apparent change in ten days ; these were both spherical and rod forms. Sample Bi. — Butter in the Box after Packing. — The cream from the attemperator or holding vats was gravitated over pipe-coolers and churned in a combination "Simplex " churn at 51 degrees Fah. The sample for plating was taken from the near surface butter as packed in the box, by means of a sterile measure. From the plates it was shown that one gram of butter contained 4,246,100 micro-organisms. They included many of the types found in the cream prior to churning, the numbers, however, being considerably reduced, many having been carried away with the buttermilk and wash waters, as a comparison with the butter- wash water will show. Of the total bacterial content 4,000,000 were " lactics," or desirable lactose fermenters ; 200,000 micrococci produced acid in litmus milk, but failed to coagulate it in ten days. The 33,100 gelatin liquefiers included Bact. fiuorescens liquefaciens, Staphlococcus aureus, Sareina lutea, Bact. proteus, and Bact. lactis aerogenes ', 3,000 bacteria were considered inert, being unable to liquefy gelatin or cause only alkalinity when inoculated into litmus milk, 7,000 were yeasts, and the 2,000 mould growths were species of Fusarium and Penicillium. Sample Bo —Butter -wash Water.— The water used for washing the butter was obtained direct from a shallow river, which flowed about 100 yards from the factory. This water was drawn through a pipe by the aid of the factory machinery, and delivered into holding tanks. The sample for plating was collected into a sterile tube direct from the tap in the churn room. 20 SCIENCE BULLETIN, No. 20. Dl Glucose Agar Plate Culture of Cream before pasteurising (dilution, 1 to 1,000). Note sjreat latent infection. The colonies developed represent 108,355,000 micro-organisms per c.c, largely coliform types. (Original.) B2 Agar Plate Culture of Cream after pasteurising by flash system, at 182 deg. Fan. (dilution, 1 to 100.) Note the effect of pasteurisation. Number of organisms reduced from 103, 355,000 micro-organisms to 14,480. (Original. DAIRY FACTORY PREMISES. 21 B3 Agar Plate Culture of Cream immediately before churning (dilution, 1 to 1,000). Held in vats overnight at 57 deg. Fah. Note the great amount of re-infection that has taken place, largely through a selected unpasteurised can of cream being used as a starter. (Original.) B4 Agar Plate Culture of butter from surface of box after packing (dilution, 1 to 1,000). Note manj- of the organisms shown in B3 have been eliminated through draining off the buttermilk and wash waters. (Original. ) 22 SCIENCE BULLETIN, No. 20. B5 Agar Plate Culture ol water used for washing butter, pumped direct from river (dilution, 1 to 1,000.) Note the enormous number of moulds, bacteria, &c. (Original.) DAIRY FACTORY PREMISES. 23 B6 B7 B8 Plates exposed to atmosphere inside factory for two and a-half minutes, showing growth of colonies of moulds and bacteria. B8 — Acid Agar Plate — Cream Atteniperator Room. B7 — Acid Agar Plate— Churning Room. B8— Ordinary Agar Plate— Cold Room at chilling temperature. (Original.) 24 SCIENCE BULLETIN, No. 20. From the plates it was found that 1 c.c. of water contained 22,800 micro organisms; 8,800 of these were proteolytic types, being able to liquefy gelatin or digest the casein of milk. They included Bad. fiuorescens liquefaciens, Micrococcus flavus, Staphlococcus aureus, Bad. cloacce, a gram positive bacillus and a sporing baciilus. The most conclusive proof that the water was heavily contaminated with the organisms of faecal origin was the presence of 6,400 per c.c. of Bad. coli. Three varieties were recognised, viz., Bad. coli communis, Bad. lactis aerogenes, and Bad. cloacce, all of which can cause gassy fermentation of lactose, while Bad. cloacce is also able to liquefy gelatin. There were 5,200 acid and acid-coagulating organisms, including 2,000 streptococci and 3,200 micrococci, while 1,400 other bacteria caused alkalinity or no apparent change. The 1,000 moulds were species of Aspergillus, Fusarium, and Mucor. Atmospherically Exposed Plates. — Sterile m^dia in the form of a jelly were melted, and carefully poured into sterile petri dishes, and allowed to solidify. These dishes were carried to the respective rooms of the factory, where the lids were carefully removed, and the media exposed for 2^ minutes to allow the free access of micro-organisms. The media used were ordinary agar, litmus lactose agar, and an acid agar specially suitable for the development of moulds. Plate B6. — An acid agar plate was exposed 2 h minutes to the atmosphere of the cream attemperator room ; it showed the development of nine mould growths, including species of Penicillium, Alternaria and Aspergillus. Plate Bl. — An acid agar plate exposed 2i minutes to the atmosphere in the churning room showed the development of two colonies of Penicillium sp. . Plate 2?3. — An ordinary agar plate was exposed 2 J minutes to the atmosphere in the cold store room. The total micro-organisms developed were twenty-one; of these, one colony was the mould Gladosporium sp., while the remainder were chromogenic bacteria. Example No. 3. The best butter of this factory, after being kept for any length of time in cold storage, showed evident signs of deterioration, although up to a week or two after being manufactured it was of choicest quality. Our investigation showed that the cream as churned was of choicest grade and had been well pasteurised. The infection that was in the cream before being heated, although large, had not had time to develop sufficiently to affect the flavour. This latent contamination was practically wiped out by the system of pasteurisation employed, as was shown by the reduction of the number of colonies in 1 c.c. of cream from 150,997,000 before pasteurising to only 500 after the heating process had been completed. After being held for nineteen hours these increased to 13,400, a striking contrast to what was experienced where a similar comparison was made in the investigations described in Examples Nos. 1 and 2. The increases in the present case were mainly due to normal increase and the multiplication of the spore-formers DAIRY FACTORY PREMISES. 25 undestroyed in pasteurising. The ^mall increase in the number of colonies after nineteen hours' retention of the cream in the closed-in batch-holder demonstrates the advantages of this system of pasteurisation, as far as reinfection from atmosphere and other outside influences is concerned. The cream after being heated is not exposed again, except when in the fluming while gravitating into the churn. This is an important consideration, especially where factories are situated near dusty thoroughfares. The air exposures made in the churn room show that there was little infection present in the atmosphere. This was to be expected, as the factory in question is situated on the highlands of the Dividing Range. Air Exposures. — Each dish was carefully exposed for two and a half or three minutes, being carried about the room so that the plate was exposed in every part. The cold room, as is usually the case, showed the presence of moulds in some numbers ; spraying or fumigating with formalin would be of benefit. Factory managers cannot keep too strict a watch on these rooms — mould is so easily carried into them by the butter boxes, the timber of which is often infected before it arrives at the factory. It would be expected that butter made under such conditions would show a small count on being plated. The contrary, however, was experienced. An enormous increase took place (principally organisms of the coli and proteus groups), demonstrating that contamination had been effected some- where— more than probably through decaying flesh and manure. An examination of the water showed that it was the means by which this infection was carried into the butter. The puzzling part was how to account for the types of bacteria encountered being found in a well 30 feet deep, into which the inflow of water was from the bottom. It was ascertained that drainage conditions were satisfactory, and there was no undesirable soakage of any kind. The tanks containing the water used for butter-washing purposes were too well closed in for infection to enter through them. It was ascertained on inquiry that, beside being used for washing butter, the well was drawn upon for the condenser of the refrigerator, and as this water was considerably raised in temperature in the operation, it was pumped up into a tower, some 20 or 30 feet high, and sprayed to the ground level, where it was caught in a shallow concrete tray and from there gravitated back into the well again. It was further brought to light that the overhead tanks used for holding water for the condensers were exposed to the air, and the bodies of drowned birds were at times found in them. Some distance from the factory, too, there was a pig-run. This was kept exceptionally clean, as pig-runs go, no offensive smells being apparent, but where there are animals there is bound to be excreta, and the opinion is held that it was from this source that the coli type of infection came, the germs adhering to the dust and small particles of dried manure, and being carried by the wind into the tower from which the water was sprayed ; entrance could easily be gained through the louvres which formed its sides. Moreover, if any pieces of flesh fed to the pigs were not all devoured, any germs produced could be carried into the water in the same way. 26 SCIENCE BULLETIN, No. 20. The process of contaminating this water had been going on in this manner for years, until the well had become thoroughly infected. The manager of the factory was instructed to get a better water supply for use in manufacturing butter, and was strongly recommended to sink another well some distance from the old one and to use the new supply solely for washing butter. The old well could then be set apart for the condensers, boiler, &c. This course was recommended in preference to trying to clean out the well by pumping, it being considered that the walls of the shaft would also be contaminated. It might be noted that the engine and boiler rooms of this factory formed a barrier between the pig-run and the butter and cream compartments ; also, on the days our examination was made the weather was calm, which accounts, in part, for the fact that the atmosphere exposures made in the churn room were so clean. This example serves to emphasise how easily such a perishable product as butter can be contaminated, and how infection can be obtained through most unlooked-for agencies. Who would have suspected that water drawn from a deep underground spring would be steeped in germs that are to be found on the surface? Here again, the care and expense entailed in properly pasteurising cream were incurred only to be partially nullified by reinfecting the butter with the water used for washing it. Water used for such purposes cannot be too closely examined. During the past few months the Dairy Branch has warned several factories on this matter, as a result of bacterio- logical examinations carried out by the Department. The last instance is one where the water for washing the butter is drawn from a well into which water soaks from an old swamp. The company has put down shafts in different directions with the same result, and as good water is seemingly unobtainable in the vicinity of the present site, the removal of the factory to where it can be got is now under consideration. A pure water supply is an absolute essential for dairy produce factories. Those factories that have one should carefully guard it from contamination. In many cases inferior water can be greatly improved by a proper system of filtering, and even where the supply is fairly good it would be all the better for being filtered — the pipes through which it is pumped in the course of time always become, to a certain extent, dirty and this sedimentary matter should be removed. Table III. — Showing Numbers and Kinds of Micro-organisms found in 1 Gram. (1 c.c.) of the following samples Samples. Total Micro- organisms. Gelatin Liquefiers and Casein Digesters. Acid and Acid Coagu- lating. Acid and Gas Forme is. Alkaline and Inert. Yeasts. Oidium. Moulds. (CI) Cream before pas- teurising. (C2) Cream immediately after pasteurising. (C3) Cream immediately prior to churning. (C4) Butter in box after packing. (C5) Butter-wash water 150,997,000 500 13,400 750,000 11,630 498,000 10 7,500 90,000 4,160 150,200,000 490 5,700 614,000 1,500 248,000 4,000 3,500 45,000 200 35,000 1,500 3,000 5,000 760 2,000 10 1,000 2,000 200 DAIRY FACTORY PREMISES. 27 Sampled — Cream before Pasteurising.— The cream, as received in cans from the various suppliers of the factory, after being weighed and sampled for testing, was graded, and the best quality pumped into a 600-gallon pasteurising holder of the batch type. The acidity of the bulk cream, after this had been well mixed by the rotating coils of the pasteuriser, was determined at 0*48 per cent, lactic acid. A neutralising agent (lime) was added in order to reduce this acidity to the requisite percentage before pasteurisation was carried out. The sample for plating was collected from the bulk cream by means of a sterile pipette in the holding vat, after blending was completed and before the lime had been added. From the plates it was evident 1 c.c. of the cream contained 150,997,000 micro- organisms; of these, 150,000,000 were Bact. lactis acidi, or desirable lactic fermenters, and 200,000 were streptococci. Of the total count, 498,000 bacteria (including organisms such as Proteus vulgaris, B. subtilis, Bact. Jluorescens liquefaciens, Bact. fulvum, and a micrococcus) were able to liquefy gelatin or digest casein of milk; 248,000 were organisms of the coliform group, or undesirable lactose fermenters, while of the 45,000 bacteria which cause alkalinity in litmus milk, Bact. alcaligenes was most numerous. Others, both spherical and rod forms, were considered inert, causing no apparent change in litmus milk or gelatin in ten days. Sample C2 — Cream immediately after Pasteurising. — The cream had been neutralised to 0*25 per cent, acidity with lime and pasteurised by means of the holding system, where the cream was raised to 145 deg. Fah.,and held at that temperature for twenty minutes. The sample for plating was collected by means of a sterile pipette direct from the vat before the cooling process began. From the plates, 1 c.c. of the cream contained 500 bacteria ; of these 490 were gram positive bacteria, which slowly coagulated litmus milk with production of acid, and ten of a sporing bacillus of the B. subtilis type. Sample C3 — Cream immediately prior to Churning. — The pasteurised cream was cooled to 55 deg„ Fah., and allowed to remain in the pasteurising vat twenty hours (overnight). The lid of the vat was kept closed, and no * starter " was added. The sample for plating was collected by means of a •sterile pipette direct from the bulk in the vat. From the plates, 1 c.c. of cream contained 13,400 bacteria. Of these, 1,900 were Bact. lactis acidi, or desirable lactose fermenters, 3,800 were streptococci, and 7,500 (including spore-forming organisms of the B. subtilis type, Sarcince and Cladothrix sp.) were able to liquefy gelatin. One hundred and fifty were bacteria able to produce alkalinity in milk, and fifty were chromogenic micrococci, classified as inert, having caused no apparent change in litmus milk or gelatin in ten days. Sample C\ — Butter in the Box after Packing. — The cream from the pas- teurising and holding vat was gravitated along a fluming into the churn in another room in the factory. The cream was churned in the Simplex churn. The sample for plating was collected by means of a sterile instrument from the near surface butter as packed in the box ready for market. From the plates 1 gram of butter contained 750,000 micro-organisms. Of these, 90,000 28 SCIENCE BULLETIN, No. 20. C1 Agar Plate Culture of Cream b3fora pasteurising (dilution 1 to 1,000). N'ote the amount of latent infection in this cream as delivered at the factory largely coliform types. (Original.) C2 Agar Plate Culture of Cream after pasteurising by holding system. at 145 deg. Fab. (dilution 1 to 10). Note the great reduction in the count, from 150,997,000 micro-organisms to only 500 per c.c. The latent infection has been killed out before the development could affect the flavour of the cream or outter. (Original.) DAIRY FACTORY PREMISES. 29 C3 Agar Plate Culture of Cream before churning, 19 hours after pasteurising, having been held at 55 deg. Fah. (dilution 1 to .100). Note that there has been no reinfection from Outside influences, such as the air, &c, but the count has increased to 13,400 per c.c. by multiplication of bacteria— lactics and spore-formers— which survived pasteurisation. (Original.) C4 Litmus Lactose Plate Culture from surface of butter packed ready for market (dilution 1 to 1,00D). Note the enormous reinfection by coli and prpteus organisms. Total count, 750*, 000 per c.c. Original.) 30 SCIENCE BULLETIN, No. 20. Litmus Lactose Agar Plate, 1 c.c. of well water used for washing butter. Note the large number of colonies, coli, proteus, and moulds, corresponding with infection found in butter. Total count 11,630 per c.c. (Original.) DAIRY FACTORY PREMISES. 31 C6 Agar Plate of air exposure for 2£ minutes in the cold room at chilling temperature. Note the slight infection by moulds, &c. (Original.) C7 Agar Plate of air exposure for 2\ minutes in the churn room. . Note the purity of the air, the locality being an elevated one. (Original.) 32 SCIENCE BULLETIN, No. 20. (including varieties of the proteus group, Bad. fluorescens, spore-forming organisms, Sarcince and Bad. prodiyiosus) were gelatin liquefiers, or were able to digest the casein of milk, and 614,000 were bacteria which, when inoculated into litmus milk, produced acid or caused an acid coagulum. Of these lactose fermenters, 500,000 were Bad. ladis acidi; 60,000 were streptococci, while the remainder of this type were varieties of micrococci, some being chromogenic. Of the 4,000 organisms of the coliform group, two members were isolated, viz., Bad. coli communis and Bad. ladis aerogenec. Of the remainder, 25,000 were bacteria able to cause milk to become alkaline ; 10,000 were considered as inert, having made no apparent change in gelatin or litmus milk after ten days ; 5,000 were yeasts, and the 2,000 moulds were species of Penicillium, Fusarium, and Cladosporium. Sample Ch — Butter-wash Water. — The source of this supply was a well about 30 feet deep. This same water was also used to flow over the condenser tower and was then allowed to flow back into the well. Samples for plating were collected into sterile vessels from the tap in the churn room and also direct from the well. The total micro-organisms in 1 c.c. was 11,630. Of these 4,160 were able to liquefy gelatin. They included varieties of the proteus group, Bad. fulvum and Sarcinae, Bad. fluorescens, Bad. prodigiosus, and several varieties of spore forming organisms. (Anaerobic spore forms were detected in dilutions of 1 to 100.) Of bacteria able to cause an acid coagulum when inoculated into milk, 1,500 were detected. These included a streptococcus and chromogenic micrococci. Undesirable lactose fermenters numbered 3,500. Of the remaining bacteria, 500 were classified as inert, while 1,000 were able to render litmus milk alkaline, and 760 were varieties of yeast. Oidium lactis was also isolated. The 200 mould growths were species of Cladosporium and Aspergillus. Example 4. In the previous examples it has been demonstrated how butter and other dairy produce can be and are contaminated by bacterial agencies, which undo all the benefits derived from the neutralisation and pasteurisation of the cream. The manufacturing company in each instance had gone to con- siderable expense in installing and operating a pasteurising plant, and the manager and his subordinates had devoted much time and effort to improving their knowledge in order to manufacture the best quality butter — one that would not only be of choicest grade for immediate consumption, but would remain so after a considerable period of storage. They desired, in fact, to produce a choicest grade article suitable for exporting overseas, or for long storage for winter requirements. It has been shown how these efforrs were rendered unavailing, and that the official butter grade certificates disclosed that the quality had either already deteriorated or was rapidly doing so, in spite of everything that could be thought of to remedy matters. DAIRY FACTORY PREMISES. 33 In each case, however, practical bacteriological examinations, carried out in a thorough and systematic manner, have solved what seemed to the managers most difficult problems. The value to the industry of science thus practically directed in the manufacture of dairy produce has been so clearly demonstrated and put on such a sound basis, that general interest has been created on the part of those employed in dairy produce factories. So great has this interest become, that the Dairy Branch has repeated requests from managers that their factories should be visited for the purpose of similar investigations being carried out. These applications will be acceded to as soon as a favourable opportunity occurs, but meantime these articles (and also lantern lectures based on the results of the examinations therein described) have been the means of awakening those engaged in the manufacture of dairy products to the important part that bacteria take — for good or for the reverse — in the various manufacturing processes that are necessary to the production of high-class butter and other products of milk, all of which may be classed as more or less perishable. The important part the factory buildings and surroundings play in causing inferior quality has been made evident in each of the examples already given. So far the factories described have been built many years — in two cases they were very badly planned in the first instance for the purpose for which they were intended, and in the first case, neglect had accentuated these bad features until the whole premises had become nothing else than a means for distributing harmful organisms, thereby enormously re-infecting at every stage of manufacture either the cream or butter. The moral it has been our endeavour to point is the need of the utmost watchfulness and care on the part of those controlling these factories in order to guard against re-infection, and the nullification of all the labour and expense involved in killing the dormant or undeveloped contamination which is to be found to a greater or less extent in every can of cream or milk as it is delivered from the farm to the factory. The dangers arising from the use of bad starters were shown in Example 2, and the need of a pure water supply in Example 3. We have also striven to drive home the need of having properly constructed premises for carrying out the manufacture of an article so susceptible to outside and surrounding influences as milk and its products. It has been thought that it would be advisable to end this present series of articles with a description of the most modern and best constructed and planned butter factory in New South Wales. This factory was only opened for use some fifteen months before we made our examination. It was planned to admit the maximum of light, to provide thorough ventilation, and to eliminate, as far as possible, all overhead floors, beams, pipes, &c. which act as collectors and distributors of dust and germs. Much attention was given to the matter of drainage and keeping the inside of the premises clean. The walls in the manufacturing rooms were lined with white opalite tiles, and all woodwork was covered with white enamel paint t 2343— B 34 SCIENCE BULLETIN, No. 20. Acid Agar Plate, atmospheric exposure for 2£ minutes in the cream receiving room of a modern factory. (Original.) Acid Agar Plate, atmospheric exposure for 2$ minutes in the butter room of a modern factory. (Original.) DATRY FACTORY PREMISES. 35 D3 Litmus Lactose Agar Plate, atmospheric exposure for 2\ minutes in the attemperator room of a modern factory. (Original.) Agar Plate, atmospheric exposure for 2h minutes in the cheese-making room of a modern factory. (Original.) 36 SCTENCE BULLETIN, No. 20. Litmus Lactose Agar Plate, atmospheric exposure for 3 minutes in the cold room of a modern factory. Note the large number of moulds. (Original.) Acid Plate Culture of butter wash-water (dilution 1 to 10). (Original.) DAIRY FACTORY PREMISES. 37 Butter-making Room in a Modern Factory. Ample provision has been made for light, ventilation, and sanitation. Cheese-making Room in a Modern Factory. 38 SCIENCE BULLETIN, No. 20. brought to a high finish. Beside having windows round the walls, light was freely admitted into each room through the roof by means of reinforced corrugated opaque glass sheets ; the ceiling, which was also painted with white enamel, followed the contour of the roof, openings being made to correspond with the glass parts, and along the ridges of the roofs ventilators were installed. A good idea of the whole structure, both inside and outside, can be gathered from the accompanying illustrations. In planning this factory the saving of labour was always kept in view. The total cost came to over £10,000, but the interest on this outlay has been more than met by the saving in labour and the improvement in quality that took place immediately the new premises were occupied. Previous to this it took thirteen men to cope with the work ; now — with an increased output — nine are sufficient, with an individual minimum wage of £3 17s. 6d. per week. Further, the change from the old dilapidated factory brought about a simultaneous improvement in the quality of the butter turned out — an improvement worth about 3s. per A well-pUnned modern Butter and Cheese Factory on a Northern River cwt. based on the condition of sales made under the imperial contract. It will be seen that the action of the directors in erecting this modern factory has been fully justified, and it has proved a most profitable undertaking to those engaged in dairying in that district. The factory is ideally situated from the points of view of sanitation and purity of atmosphere. It fronts a tidal river, and is bordered on the other three sides by green fields. The plate developed from a *2| minutes exposure under the cream vat platform, which is open to and on the same level as the churn room, gave no evidence of moulds or bacteria being present. The methods of making these exposures were similar to those described in previous articles, and the results showed that the premises and surroundings were remarkably free from infection — with one exception. The plate D5 — three minutes air exposure in the cold room — shows that this room was much infected with mould. Mould was also found on the timber used for making butter-boxes, having evidently been brought into the factory from tho timber mill and box factory. The room where this DAIRY FACTORY PREMISES. 39 timber was stored in shooks, and where the butter-boxes were put together, adjoined the butter-making room, and an exposure made in the current of air flowing between the door from this rcom to the outlet on the opposite side of the churn room also showed the presei.ce of mould organisms in numbers, while the plates exposed on either side of this draught showed little or no growth — thus demonstrating how the spores were being carried right through the building and out the other side by the wind, after having been disturbed in the box room, perhaps while the infected timber was being shifted or while the different pieces were being nailed together. Possibly the force of the wind off the river was sufficient to lift the spores off the colonies growing on the wood, without the latter being moved at all. The boxes, after being filled with butter, were carried into the cold room and stacked almost to the height of the ceiling. At the time of examination this room was almost filled. In putting the boxes on the tiers, mould spores would be dislodged, and they were in the air at the time the exposure was made, with the result shown in D5. The manager of the factory was notified as soon as possible of what was taking place, and advised to close or re-arrange the. connection between the timber storeroom and the manufacturing portions of the building, and to have the cold room emptied as soon as could be arranged so as to thoroughly fumigate it or spray with formalin. He was also advised to destroy the moulds then on the butter-box timber before making up more boxes. It is understood these suggestions have been given effect to. This is a striking illustration of how easily the newest and best planned dairy produce factory premises may be infected, and shows what an amount of watchfulness and care is necessary to keep everything connected with the manufacture of dairy produce free from sources of contamination. The factory manager must be ever on guard against re-infection. Water used in Manufacturing Butter. — In the present example the plate D6 indicates a water of unexceptionable purity, judging by the small bacteriological count. This is in marked contrast to other waters examined, notably in Examples Nos. 2 and 3 described in the previous articles. In the present case the water is obtained from a spring near the surface, the current draining rapidly into an excavated reservoir through a bed of water-worn coarse quartz gravel and sand. This reservoir is situated about half a mile from the factory, to which the water is brought through galvanised iron pipes by pumping. Good though this water is, it might be still further improved by filtering, in order to free it from sedimentary matter which will, as time goes on, accumulate more and more in such a length of pipe line. While on the subject of butter-wash waters, it may be of interest to mention the case of another butter factory which had been in trouble for some time through the bad keeping quality of the product turned out. This is one of the several cases recently investigated and remedied to the satisfaction of the manufacturing company. Samples of water (taken from 40 SCIENCE BULLETIN, No. 20. the source of supply — a well) were examined and found to be heavily polluted, among other organisms present being members of the coli and proteus groups — evidence of surface contamination. The manager of the company, on being advised of the results of the first examination, caused shafts to be sunk in various directions round and more or less distant from the factory. * Samples of the water thus obtained were sent to the Department, and on examination they were found to be similarly infected to the sample first sent in. On inquiry it was ascertained that this factory is situated in the midst of low-lying swampy country, the underground supplies of water evidently having soaked through the surface * soil. The directors of the company have now decided to remove the factory to a site where a purer water supply can be obtained — a commendable step. A good water supply is an absolute essential to the manufacture of good butter. Now that pasteurisation has been generally adopted in order to kill off or prevent the development of injurious organisms that have obtained- access to the milk or cream, it is manifestly the height of folly to allow as fresh infection to take place by washing the butter in the churns with con- taminated water. A water-filtering plant should form part of the equipment of every factory. In the majority of cases it would remedy matters : if not, a new and clean supply should be obtained if at all possible. Even if the factory had to be removed, it would be an expenditure well undertaken. Sydney : William Appkgate Gullick. Government Printer — 1921. 14 DAY USE RETURN TO DESK FROM WHICH BORROWED AGRICULTURE UlBr 40 G1ANN1NI HALL EXT. 4493 This book is due on the last date stamped below, or on the date to which renewed. Renewed books are subject to immediate recall. APR 2 o5 y ^ Vrj'b/ —■ Wi \ [*IliAJflC^ \ (D6471sl0)476 Berkeley