THE DAIRY.

New Zealand Mail, Issue 1217, 28 June 1895, Page 8

THE DAIRY.

BUTTER-fViAKiNG.

A SOUTH AUSTRALIAN OFFICIAL

REPORT

The manager of the South Australian London Produce Depot, Mr E. Burney Young, has forwarded to the Minister of Agriculture a report on butter-making. i Mr Young says : Since the invention of centrifugal creaming the mechanical part of buttermaking, creaming, churning and washing has been so greatly improved that we may say that it is in first-class style in most dairies. Such is not the case in I the chemical part of the manufacture, ! which has only been made a subject ; of a.udy during the past two or three years. Great differences, it is true, were remarked in the quality of butters according to thfiir origin, or even the time of manufacture, but such variations were only attributed to the breed of cows and the kind of fodder, which have a great but not the only influence. It was also known that the be3t butter? (Isigny, Goumay, &c.)- were made by the system of spontaneous creaming, whereas those made by immediate churning of cream from centrifugal creamers had little or no aroma and were rather like fat. Some persons concluded from these facts that centrifugal creaming could not give butter of a good quality ; others of greater experience considered that it was requisite that the cream of the centrifugal creamer should be placed in similar conditions to those of cream—allowed to separate slowly from milk at rest —iu order to obtain equally good butter. In this case the main part of the cream formed firstly by the largest butyrous globules rises to the surface rather rapidly, where it remains in contact with the air for a certain number of hours, whilst the small globules are ascending As much, then, must be done with the cream of the centrifugal creamer by leaving ib in contact with the air for a sufficient time before churning. This ripening of cream in the centrifugal creamer has greatly improved the quality of the products, but none the less this quality has remained very variable, because as a rule the cream is churned a day or two after the operation of churning without any attention being given to the temperature of ripening, or to the degree of acidity of the cream at the time of churning. '

Importance of Ripening Cream before Churning. —Yet this fermentation of cream is of the greatest importance as regards the quality of the butter and its preservation. The studies made in Denmark on this question by Storch and other men of science, as also the good results obtained in this country by the employment of fermented creaniß, clear the question from all doubt. Besides, in France several dairies where these methods are employed obtain remarkable products. M. Duclaux, iu his " Principes de Laiterie," judiciously remarks that butters made with sweet cream do not possess the aroma of butters made with fermented cream, and that consequently this aroma resuiis from the products engendered in the cream during ripening bv certain microscopic organisms or ferments. Experience fully corroborates these conclusions, and bere are two samples of butter made with the same sterilised cream, divided into two parts, one of which was fermented before churning, and the other not ; the butter made with the fermented cream presents an aroma not found in the other sample, the flavour of which i*i very like that of any alimentary fat. [lt would be interesting to repeat these experiments working with milk drawn from the udder out of contact with the air, taking all the necessary precautious to assure asepticity, ascertaining at need the sterility by putting the milk into the stove. This milk should then be at once creamed in the centrifugal creamer, and part of the cream churned forthwith, all the work being executed in aseptic surroundings; the other part of the cream should bo churned after being sown and fermented.] We may then bo assured that creams properly fermented give buttei'3 of superior quality, which will keep well ; but in order to obtain such results we must apply in the fermentation of cream the general method prescribed by bacteriology which is employed in the other industries of fermentation (wines, beers, etc.)- This method, in brief, consists in iavpuring the action of good ferments, and checking that of the bad ; before all else then we must be able to distinguish those ferments, and know their conditions lof existence. Limiting ourselves to cream, we shall remark that it may contain all tho milk microbes, which, as you are aware, gentlemen, are conveyed by tho air. Amongst these ferments there are some which develop in the cream elements which impart a pleasant aroma to tho butter, whilst others, on the contrary, cause decomposition which result in defective butter. If we succeed in isolating the ferments which exert a beneficent action it will suffice to sow these ferments in tho cream previously cleared from all microbes it may contain, and kept at the temperaturo most suitable for the growth of the ferments sown ; thus the quality of the butter will be invariably good. The cream will thus ripen in clearly defined and unchangeable conditions, which is not so in tho case of cream which, when separated from the milk, is left exposed to the influence of the bacteria of the air and placed in con-

ditions of temperature quite undefined.

As regards the time of churning it must not be fixed by tho time elapsed since creaming, but by the degree of ripeness of the cream, which is the only factor of interest in the case in question. Let us at once remark that the works of scientists and experienced manufacturers who have studied this important question have nmdo it possible to realise the conditions we have enumerated in a satisfactory manner.

Lactic Ferments.—The ferments to which the famous butters of Isigny and Goumay owe their delicate aroma have been successfully isolated, and pure cultures of these ferments can be bought, aa you can see from the samples which I now show y:>u, for which I am indebted to the kindness of Messrs J. and G. Fabre, the well ki own manufacturers of French rennet and colours for butter and cheese.

Sterilisation of Cream.—As for sterilisation of cream, it can very easily be executed in small dairies by heating it in a water-bath at about 75 degrees C. (167 degrees Fahr.) and then cooling it to the most suitable temperature for ripening, 18 degrees C. (64*4 degrees Fahr.). In large dairies these operations will be executed by, means of special apparatus which 1 shall describe later. It is the degree of acidity which indicates the exact moment when the cream should be churned. When this degree is too weak the arena of tho butter is imperfectly developed, when too strong the flavour of the butter is rancid. We shall see how this degree is found by aid of the acidimeter. Let us now examine the method of treating the cream from the time of creaming until that of churning. Pure cultures of lactic ferment, like the samples in my hands, are obtained by sowing sterilised milk with ferments carefully collected from the creams which give the best butters (Isigny, Gournay)at the precise instant when these crfiams are ready for churning. These cultures, as you can perceive, are in the form of milk, thickened by tho action of ferments. They should not be kept for long because the microscopic organisms which constitute the ferment cannot live when the decomposition they engender has reached acerain degree. There are also powdered ferments, which are simply fecula steeped in liquid ferment, and dried at a low temperature.

Sowing the Cream.—The cream should not be directly sown with the lactic ferment, because it would require too much ferment to obtain proper ripeness in a reasonable length of time. A mother* ferment is prepared with trie commercial ferment, and employed to sow tho cream. For this operation you must take a volume of milk equal to 4 per cent, of the cream to be treated. This milk, which may be skimmed, is pasteurised by heating at 90 degrees or 100 degrees C. (194 dogrees or 212 degrees Fahr.), then copied to 18 degrees or 20 degrees C. (64'4 degrees or 68 degrees Faht.). Then pour the contents of a bottle of lactic ferment into it, and cover the vessel with line muslin, which allows tho air to pass, but retains the dusts, and then let it rest at a temperature of 18 degrees to 20 degrees C. (64-4 degrees to 68 degrees Fahrj until the milk has coagulated completely, which usually requires some twenty hours. All the lactic ferment must be employed whatever the amount of milk, because the ferment is injured by contact with the air when the bottle is uncorked. The cream, as wo have said above, is pasteurised en leaving the creamer; it is then cooled to 16 degrees to 20 degrees C. (60 8 degrees or 68 degrees Fahr.), then sown with the mother-ferment at the rate of three parts of ferment for 100 of cream. The remainder of the ferment is employed to prepare that ».f the next day and so on. However, it is well to renew the ferments every 15 days at least in order to, avoid the inconveniences which result from.the growth of germs conveyed by the air into the milk employed for making the mother ferment, and from the weakening which occurs with time in the strength of this ferment.

Determination of the Acidity of the Cream. —Fermentation of the cream should be continued until the acidity is 60 degrees to 65 degrees. This acidity is measured with the Dornic acidimeter. When the acidity of the cream has reached the proper degree (60 degroe to 65 degrees), which in the conditions indicated requires some 20 hours, churning can be executed after cooling the cream to 14 degrees or 15 degrees C. (57*2 degrees or 59 degrees Fahr.). The greatest cleanliness is essential in all these. All the vessels must be washed in boiling soda and water, and sterilised by steam. Attention must be given to the iron or copper vessels, because lactic acid sharply attacks these metals, and tho butter made with cream kept in such vessels would have a bad flavour.