Researchers from Brazil, Iran and Italy collaborated on the review which, according to one of its authors, was written with the aim of highlighting sheep milk’s potential, especially compared to cow milk.
“Sheep milk could… be a food category to deliver [prebiotic and probiotic] ingredients to humans. Sheep milk is not only to produce fine cheeses or creamy yoghurts,” said lead author Celso Fasura Balthazar, a researcher at Fluminense Federal University in Brazil.
“Moreover, there are studies demonstrating high similarities in terms of milk protein between sheep milk and goat milk. Goat milk is hypoallergenic, but there is a lack of studies with sheep milk elucidating this aspect,” he added, saying he hoped more research would follow.
“I consider that all functional food made with cow milk could also be produced with sheep milk. The important to have in mind is that sheep milk has unique characteristics, as with goat or buffalo milks; because of that we should study the peculiarities of sheep milk to know the best way to develop dairy products, taking advantage of these peculiarities to create more natural and healthier foodstuffs,” said Balthazar.
The authors noted in the review that sheep milk’s high levels of protein and fat, which make it so attractive for cheese production, could also give greater protection for probiotic bacteria in the gastrointestinal tract, as well as during storage.
“The high protein level is also a favourable characteristic for the production of fermented milk because high protein levels confer nutrients that are available for microbial growth, leading to a reduction in fermentation time with no direct impact on the manufacturing process,” the authors wrote in their paper, published in the journal Comprehensive Reviews in Food Science and Food Safety.
Inulin fibre works well with sheep milk
In terms of prebiotic uses, the researchers note studies, including several from Balthazar and others in recent years, suggesting the milk’s fat could be replaced by inulin fibre, a prebiotic, which could also improve mouthfeel.
A 2015 study suggested adding up to 6g of inulin per 100g of sheep milk yoghurt had little negative impact on sensory acceptance, and improved flavour acceptance, while improving the appearance of the yoghurt.
A study published last year found inulin also delayed the postacidification process of sheep milk yoghurt in chilled storage for 28 days.
“The lower acidic environment is an ideal condition under which to add probiotic bacteria to the food matrix, which is sensitive to the postacidification of yoghurt. … Inulin addition did not interfere in the cell counts of the starter culture (S. thermophilus and L. bulgaricus) and no significant changes have been observed in the fatty acid levels,” the authors wrote.
They concluded: “Sheep milk is an excellent source of nutrients and is mainly used for cheese production due to its high total solids content, contributing to a high cheese yield.
“However, the functional benefits of this food matrix remain unexplored by the dairy industry. The development of products on an industrial scale requires technical knowledge and adaptations of the existing protocols due to the intrinsic characteristics of this matrix.”
Source: Comprehensive Reviews in Food Science and Food Safety~
Published online ahead of print, doi: 10.1111/1541-4337.12250
“Sheep Milk: Physicochemical Characteristics and Relevance for Functional Food Development”
Authors: Balthazar, C.F., et al