Farm Notes.

Te Aroha News, Volume XXVII, Issue 4444, 3 August 1909, Page 4

Farm Notes.

PASTEURISATION OF 8KIM- ; - MILK AND WHEY.

Tbe pasteurisation -of cream for butterimaking is now coming rapidly Into favour in New Zealand, and, as each season comes round, the example of those who have adopted the system ; wiH undoubtedly be followed by dthers, for the simple reason that a snore uniform and better-keeping product can be manufactured under this method.

As a natural sequence, some interest is also being devoted to the extension of the practice of pasteurisation to the by-products of the dairy factories namely, skim-milk and whey. The urgent necessity for this change, as well as the advantage to be gained by its adoption, has been discussed time and again at the

yearly conferences of dairymen, and also at numerous meetings of farmers in different parts of the country. The primary benefit to be gained by the process is the prevention of the spread of disease amongst the calves and .pigs to which the skim-milk and whey are fed, more especially amongst pigs, on account of their greater susceptibility to disease; but there are other important reasons as well. The evidence of the efficiency of the process in this direction is so conclusive, and is brought home to the farmer so frequently, that one is amazed that pasteurisation has not long ago been lusisted upon. While great strides in pasteurising milk have been made in other dairying countries—in some of which pasteurisation of the separated milk, as well as of all cream, has been made compulsory by law—practically nothing has as yet been attempted in New Zealand, except as regards the treatment of a portion of the cream. It ha!s been proved elsewhere that not only is the dissemination of disease prevented, but also the feeding value of both whey and skim milk is

greatly improved, by their being heated to the required temperature Another advantage that should not be lost sight of is the benefit to be derived from the purifying effect which the hot liquid has on the tanks into which it is run before being delivered to the milk suppliers ; and this ap* plies to the milk cans also. Under the existing conditions it is safe to say, that much of the troubie at the factories with inferior milk is due to

the milk cans being polluted by the

conveyance in them of impure -whey to the farms from the often evil-

smelling and dirty tanks, these being seldom cleaned as they should be.

The cans are thereby made difficult to clean, and it often happens that a thorough cleaning is neglected, with the result that the whole milk is seeded with harmful bacteria, which seriously affects the flavour of the produce made from it. Pasteurisation, or heating, of the whey is highly desirable from this point of view alone. The principle objection to pasteurisation by many dairy farmers has been on the score of increased expenditure at the factories, the contention being that the fuel bill would be increased enormously. In order to prove that the work could be carried out at a very moderate expense, the pasteurisation of skim milk and whey was undertaken by officers of the Dairy Division, at the cost of the De-

partment of Agriculture, at two factories in the North Island. Arrangements were made with the Hawera Dairy Company to pasteurise for several days, with direct steam, the whey at the Company’s central factory. A similar arrangement was made with the Ballance Dairy Company in regard to the sirim milk, with the exception that a modem pasteuriser was in« stalled for the purpose. From the reports supplied by Instructors Singleton and Pedersen, who were directed to carry out the work, and which are given below in full, it will be seen that the cost of heating the skim milk and whey cannot be raised as an objection to the introduction of the system of pasteurisation as applied to these by-products. A glance at the figures given will show that when the exhaust steam was used to heat the skim milk the expense for fuel was almost nil. Worked out on a basis of cost for fuel per pound of fat in the whole milk, and taking that at 3.9 per cent, (which is the average test of milk supplied to factories in New Zealand), it would only mean an expenditure of 0.025 d per pound of fat when direct steam is used in the pasteuriser. Utilising the exhaust steam, and calculating on the same basis, the cost works out at 0.0033 d per pound of fat in the whole milk. In the case of heating the whey with a jet of steam direct into the liquid, the cost per pound of fat in the whole milk is 0 O4lod.

It is, of course, not expected that the pasteurising of the skim milk and whey at every factory could be done for quite such a low price as this; fettt at the factories where the work was done there were no special advantages which would tend to cheapen tha actual cost; therefore, it is fair to assume that pasteurisation could be carried on at any ordinary factory with equal economy, provided reason** ablcrcare is taken to prevent waste. The first cost of installing the pasteurising plant to treat the skim milk would depend on the quantity of milk received at the factory, and the speed at which it was decided to run the milk through, and may be set down as follows: — £ For a factory handling 450 gal per hr 40 ~ 650 ~ 65 „ 800 „ 85 „ 1,000 „ 105 „ 2,000 140 For heating the whey with a jet of

live steam the cost of the steam piping, valves, etc., would be the only outlay, and this would depend on the distance of the whey tanks from the factory, but should not exceed £6 or £8 at the outside-