Butter Concentrate
Never used it, so did a Google search which says
“This tin of butter concentrate was produced by the Queensland Butter Board (Q.B.B.) having been developed by them between 1944 and 1946 with the assistance of the C.S.I.R. Butter concentrate is similar to clarified butter or ghee and has the advantage of being able to be kept for up to two years without refrigeration. Water, lactose and casein protein are removed from pasteurised cream or butter, although it can also be made from milk. The butter is then centrifuged and heated.
Tinned butter concentrate went on sale to the public in 1946 in 12 oz (340g) tins. As it kept so well, it had been supplied towards the end of World War II to Allied forces serving in the tropics. It was also a popular inclusion in food parcels sent to Britain during rationing after the War. Once export controls were lifted, there was great demand for it from overseas countries especially to South East Asian markets.
However, butter concentrate was not without controversy, fanned by competitors. The Victorian dairy industry tried to have the product banned from sale there on spurious health grounds and even in Queensland, dairy farmers sought to have its sale banned in the city while acknowledging its usefulness in remote areas.
Butter concentrate can be used to enrich milk made from powdered milk to improve children's nutrition in third world countries and is widely used industrially in the making of a range of foods including cakes, ice cream and ready-made meals.
Judith Campbell, Powerhouse Museum volunteer, under the supervision of Margaret Simpson, Curator
August 2020”