Dairy Sheep Symposium - the Department of Animal Sciences ...

Dairy products development
Our project addressed the lack of specialised dairy products made with sheep milk by developing
new sheep milk products that were initially tested on small groups of people to assess their
acceptability to Australian consumers. This resulted in the development of methodologies for the
production of two new cheeses. One of these is a soft spreadable cream cheese that has virtually
no maturation time. It was developed to respond to the need of manufacturers for a fresh product
that would provide the 'cash flow' for the enterprise. The other is a semi-mature cheese that has
to be aged for about one month. Both cheeses were tested on a large group of consumers through
a survey in a popular supermarket chain. Both cheeses were rated highly by potential consumers,
who were disappointed to hear they could not purchase our products. The survey revealed
that 86% of consumers were prepared to buy both cheeses at a price of $21/kg (±1.02) for the
semi mature and $32/kg (±0.8) for the spreadable cheese, confirming the existence of domestic
markets and a consumers willingness to pay high prices for sheep milk products.
Another product developed within our project was sheep milk ice-cream in collaboration
with our industry partners, the Peters & Brownes Group, who are major exporters of ice-cream to
Japan. We investigated the effect of fat concentration on the quality of sheep milk ice-cream.
Batches of sheep milk ice-cream containing different concentrations of fat were produced and
tested by an expert panel at the R&D Laboratory of the Peters & Brownes Group. The batches
were scored poorly by the panel regardless of the fat content. By contrast, they were considered
generally good by Animal Science staff. Since members of both organisations may have been
biased against or in favour of the sheep milk ice-cream, this conflicting result was further investigated
by conducting a blind test on a small number of potential consumers. Consumers were
unable to distinguish sheep milk ice cream from cows milk ice cream, supporting the possibility
that the experts at P&B were prejudiced against the sheep milk ice cream. However, the participants
stated that they were not prepared to pay more money to purchase the sheep milk ice
cream. This was to be expected, since according to the participants there was no difference in
taste between the two products.
Producers had also reported problems in processing sheep milk harvested in early lactation.
We investigated the presence of colostrum immunoglobulins that are essential for the welfare of
the lambs, but that could be the cause of the reported processing problems. To test this hypothesis
sheep were separated from their lambs and milked immediately after lambing and samples of
milk were collected daily and analysed for the presence of colostrum immunoglobulins by
Capillary Electrophoresis. We found that colostrum immunoglobulins persisted in the milk of
some ewes for up to nine days after separation from the lambs. Sheep dairy producers that milk
the sheep immediately after they have given birth should therefore discard the milk for at least
one week.
There was also the possibility that processing problems in early lactation could be due to the
presence of an unbalanced ratio of fatty acids in the milk fat as in early lactation the sheep could
mobilise body reserves to synthetise the milk fat. In this case the milk fat would contain more
unsaturated long chain fatty acids as this is the form in which the mammary gland cells transform
the fatty acids that come from body fat tissue. Short/medium chain fatty acids increased from 33
to 40% with the progression of lactation, supporting the hypothesis.