THE UTILIZATION OF WHEY.

New Zealand Journal of Agriculture, Volume XXXVIII, Issue 1, 21 January 1929, Page 36

THE UTILIZATION OF WHEY.

ECONOMICS AND TECHNIQUE OF CONCENTRATION

M. A. F. Barnett, M.Sc., Ph.D., Physicist, Research Department, Wellington, in the New Zealand Journal of Science and Technology.

In England the problem of the utilization of whey became one of very great importance not so much because of any economic wastage, but because the disposal of the unwanted whey presents the greatest difficulty, due to the nuisance produced when it is discharged into sewers or streams, &c.

. In New Zealand this latter aspect is not of such grave importance, but from the economic point of view an investigation is obviously warranted which might lead to a profitable utilization of the enormous quantities of whey at present going to waste. Based on the production figures for cheese, the total annual output of whey in New Zealand is about 600,000 tons, and of this quantity about 42 per cent, is produced in the Taranaki District, 16 per cent, in Wellington, 151 per cent, in Southland, and 14 per cent, in the Auckland Province. If, for illustration, we assume that this whey is worth a farthing per gallon, the value of . the annual output for New Zealand is about £140,000.

A certain proportion of the whey produced is already used for feeding direct to pigs, but there are some important drawbacks to this practice. In the first place, whey is so dilute—containing about 94 per cent, of water — pigs would have to consume impossible quantities in order to assimilate an appreciable amount of solids ; and, secondly, if whey is kept for any length of time in the dilute form it develops an increased acidity, which gives it a strong laxative action, rendering it of still less value as a pig-food.

On the other hand, if the whey is first concentrated by evaporating off a considerable amount of the water, both these troubles are overcome. The percentage of solids being much higher (say, 60 per cent, solids in the concentrated form), the pigs are able to assimilate more readily an appreciable amount ; and, secondly, it is found that the concentrated product will keep indefinitely without developing any further acidity. Any concentration accompanied by better keepingqualities will enable the whey to be stored readily, to be available for feeding over a longer period of the year, and transported at less cost.

A typical analysis is here given showing the composition of whey after the bulk of the fat has been separated for the manufacture of whey butter : Water, 94-70 per cent. ; fat, 0-06 ; lactose, 3-51 ; protein, 0-78 ; ash, 0-51 ; lactic acid, 0-44 ; total solids, 5-30. It will be

seen that of the solids about 70 per cent, is lactose. The price paid for purified lactose makes its extraction from whey a profitable; undertaking, but unfortunately there is only a very restricted demand for this article. The total annual consumption of milk-sugar for the whole of England is only - about . 400 tons, and this demand is already fully met. '

When it is considered that the whey produced per year in New Zealand contains a total of about 20,000 tons of lactose, it is obvious at once that its extraction on a large scale is not feasible unless there is a complete revolution in the demand for this product. Precisely similar reasoning applies to . the wholesale extraction of albumen, even if this were an economic possibility. One sugar-of-milk factory already in existence in New Zealand can supply all the requirements of this country, together with the demand from available markets outside. It would seem, therefore, that the only outlet for the utilization of whey on a large-scale at the present time lies in the production of a concentrated product, from which a large percentage of the water has been removed, which would be suitable and find a market as a stock-food, more particularly for feeding pigs. Experiments are at 1 present in progress, along these lines.

The problem of the utilization of whey in England has been investigated by Dr. Harding, who did some preliminary work in 1922 for the Royal Agricultural Society of England. Later he carried out some large-scale experiments for the Ministry of Agriculture. The results of this work are published in Research Monograph No. 5 of the' Ministry of Agriculture, “ The Whey Problem and a Solution,” by Leonard Harding, Ph.D. The paper describes the method adopted for condensing the whey at the cheese-factory, and deals fairly fully with the subsequent extraction and refining of the milk-sugar. The production of whey foods is dealt with briefly, and useful details are given of the costing of the various processes, and of steam requirements, &c.

In Harding’s experiments an evaporator was set up at the Whitchurch branch of the United Dairies, Ltd., and the sugar - extraction was carried out at a factory at Haslington, some distance away. The whey condensed at Whitchurch was conveyed to Haslington in specially made 20-gallon churns. This arrangement was made to demonstrate the possibility of individual cheese-factories concentrating their whey before sending it to a central factory for sugar-extraction and stockfood production.

A specially-designed double-effect evaporator, utilizing a dry pump and barometric condenser, was employed at Whitchurch. - The evaporator was capable of handling 2,000 gallons per day of eight hours, and it was worked so that the temperature in the first effect did not exceed 70° C., in order to avoid coagulation of albumen. The whey was condensed till it occupied less than one-tenth of its original volume, 100 gallons of the liquid being reduced to 8-75 gallons of the concentrate, which then weighed no-8 lb. The concentrate is in the form of viscous liquid, and can be poured into cans for transport. ' :

Tests on the evaporating plant showed a total steam-consumption (including steam for water-pump) of 5-85 lb. per pound of condensed whey produced. With an efficiency of 7 lb. of steam per pound of coal this means slightly less than 1 lb. of coal per pound of condensed whey.

Water was required for the condenser at the rate of 6,000 gallons per hour. At Whitchurch this water was drawn from one end of a comparatively stagnant brook and returned at the far end, the water being kept sweet by the addition of about | lb. of chlorine daily. One man was able to look after the whole plant.

Taking the Whitchurch figures, and with coal. at £1 ss. per ton, the cost of coal is about £1 2s. 6d. per ton of condensed whey. For labour, one man (at £3 per week) produced 12,000 lb. of . condensed whey per week. This works out at £1 14s. per ton of the concentrated product (60 per cent, solids) for steam and labour on the evaporator. To this must be added interest on the plant (cost about £2,200) and depreciation, &c. Also, there is additional labour involved in the extra boiler-stoking required, and in some cases a larger boiler might have to be installed.

Harding’s method of extracting the sugar is described in detail in the pamphlet. Whey foods were produced from the residue after removal of the greater part of the sugar, thus giving a higher protein/ carbohydrate ratio to the food than is obtained with direct concentration without any sugar-extraction. In one case the liquor was dried when mixed with a suitable drying agent in the nature of a foodstuff — e.g., bran, sharps, or grains, &c. ; in the other it was simply concentrated by evaporation to a semisolid mass and sold in barrels. In either case it sold at about £l2 per ton ; but the latter was the more popular, although still containing about 34 per cent, of water. Both proved valuable as a pig-food.

In conclusion to the pamphlet, Harding says, “ It is submitted that the work described in this report has demonstrated that—(l) Whey can be condensed to less than one-tenth of its bulk in an economic manner, without interfering with subsequent extraction processes; (2) condensed whey will keep indefinitely and can be easily transported in suitable packages ; (3) given a sufficient quantity of raw material, at a central factory, milk-sugar and animal-foods can be economically produced from condensed whey.”

In New Zealand an investigation is being carried out by the Department of Scientific and Industrial Research to test the economic possibilities of using concentrated whey as a pig-food. Practical tests on the concentration of whey were made at the sugar-of-milk factory at Edendale, using the existing plant, which consists of an American double-effect evaporator made by Swenson. This evaporator is a very simple type, in which the heating steam passes through a series of pipes immersed in the whey. This kind is much easier to keep clean than, the type used by Harding, in which the whey boils inside the tubes,, which consequently require frequent cleaning.

. Tests have been made working the evaporator at 15 in. vacuum in the first effect and 25 in. in the second. There is slight trouble due tofrothing, but this can be overcome by the addition of a small quantity of cotton-seed oil (or other cheap vegetable oil). The temperature in the first effect (Bo° C. for 15 in. vacuum) is probably sufficient to coagulate the albumen, although no trouble from that source is apparent. The plant is probably capable of dealing with about 1,000 gallons of whey per hour, which would mean an output per eight-hour day of 3 tons (or more) of condensed whey produced from 6,000 gallons of

whey. Two thousand gallons of whey is condensed to a volume of 200 gallons, which weighs about a ton and contains approximately 60 per cent, of solids.

The tests indicate that not more than i| tons of coal is required for all purposes per ton of whey paste produced, and this figure could probably be reduced. For labour, an evaporator of this size (3 tons output per day) one full-time man together with an extra bciler hand would be required, with possibly occasional assistance. As to capital cost, £3,000 is an estimate of the total installed cost of an evaporator of the type at Edendale. On the. assumption that the existing cheesefactory boiler can supply the steam required, which is probably not justified (see below), a rough estimate of the cost of production of 3 tons of whey paste would be as follows : tons coal at £1 10s., say, £6 15s. ; labour —two men, per day, £2 ; interest and depreciation per day (200 days per year), £1 15s. : total, £lO 10s.

This is about £3 10s. per ton according to cost of coal, and no allowance has been made for any payment for the whey (2,000 gallons needed per ton of paste would cost £2 at |d. per gallon), or for barrels or other receptacles, &c. Also, the following figures indicate that additional boiler-capacity would be required at many factories. Take as a typical example a cheese-factory with an annual output of 400 tons making during the flush season 2 tons of cheese per day and utilizing a 20 h.p. boiler : Two tons of cheese per day would mean a production of about 4,500 lb. of whey per hour for eight hours each day. For concentration in a double-effect evaporator this would require approximately 3,000 lb. of steam per- hour (over the eight hours'), which represents the full output from a boiler of about 86 h.p. capacity. For the examples quoted, therefore, the existing 20 h.p. boiler would be quite inadequate. For smaller factories and periods other than the flush season there would be much less divergence between the steam required and that available from the existing boiler.

Analyses have been made of the whey paste produced at Edendale, and the following is typical: Water, 49 per cent. ; protein, 6 ; ash (mineral), 4-7 ; acidity (as lactic acid), r-2 ; fat, 0-3 ; sugar (by difference), 38-8.

Several tons of the paste have been prepared and distributed for trials of the feeding-properties for pig-raising at Lincoln, Weraroa, Palmerston North, and Ruakura. Its food value is also' beir.g tested by Dr. Malcolm at Otago University.

Improvement of Second-groivth Country.— The annual report of the Fields Division for 1927-28 states: The Lands Department is now conducting a demonstration farm in Whangamomona County under the provisions of the Deteriorated • Lands Act. This farm is being run on economical lines, but, with the work that is being put in to it on good-management methods, considerable improvement both as regards carrying-capacity and appearance is already being shown. The instructional officers of the Fields Division continue to co-operate with the officers of the Lands Department in the work necessitated in connection with advances under the Deteriorated Lands Act, particularly in the King-country.”

[Note. —Reports on certain of these trials will he published in a subsequent issue of the Journal of Agriculture.— Ed.] >