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Donkey milk research · Study 172
Donkey milk in the fridge and freezer: what changes after 90 days
Pasteurised milk from Amiata jennies kept its main constituents during up to 21 days of storage at +3 °C and up to 90 days at −20 °C. According to the authors, only lactose fell after 90 days of freezing, and some fatty acids changed slightly. Enterobacteriaceae were never detected, and the colony count at 30 °C never exceeded 1 log CFU/mL.
At a glance · tap the cards
The key figures
Study design
How it was studied
Short communication by a research group at the University of Pisa (Italy): milk from Amiata jennies was pasteurised at 65 °C for 30 minutes and then stored for 21 days at +3 °C (± 2 °C) and for up to 90 days at −20 °C (± 5 °C). The milk was monitored chemically (main constituents, fatty acids) and microbiologically (including Enterobacteriaceae and colony count at 30 °C). Assessed based on the abstract; numbers of animals and samples, measurement time points and specific contents are not stated there.
Results
What the study measured
Enterobacteriaceae were found neither in the pasteurised milk nor during refrigerated or frozen storage. The requirements of EC Regulation No 1441/2007 were thus met.
The colony count at 30 °C in pasteurised milk never exceeded 1 log CFU/mL.
According to the authors, heat treatment and storage did not change the main constituents of the milk.
After 90 days at −20 °C, lactose decreased and some fatty acids changed slightly.
According to the authors, fat quality was maintained during refrigerated and frozen storage. The abstract gives no specific contents.
Authors’ conclusion: According to the authors, pasteurisation achieved and maintained a high hygienic quality over time; refrigerated and frozen storage did not alter fat quality or gross composition. The authors see this as a contribution for infants who need small daily quantities of milk. Only the milk was studied – suitability for infants was not examined.
Critical appraisal
Strengths and limitations
Only the abstract assessedNote
Sample numbers, baseline values of the raw milk and specific contents are unknown without the full text.
Sample basis of storage unclearNote
The abstract does not make clear whether the storage tests were carried out only on pasteurised milk. The findings cannot be transferred directly to raw frozen milk.
One breed, one research groupNote
Milk from Amiata jennies was studied. Other herds, feeding regimes and lactation stages may differ.
Infants only in the conclusionClear limitation
The conclusion mentions infants, but only the milk was studied. No statements on infant feeding can be derived from it.
Hygiene and nutrients togetherStrength
The study looks at microbiological and chemical values together over a storage period of up to 90 days.
Editorial note: The short communication shows that the gross composition of pasteurised donkey milk changed little during refrigerated and frozen storage in this experiment; lactose decreased after 90 days at −20 °C. Without the full text, the size of this decrease remains open. To the research archive.
Research question for DON DONKEY’S®
How do lactose and fatty acids change in frozen raw donkey milk after 30, 60 and 90 days at −20 °C, measured on the same batch?
Original publication
Effects of pasteurization and storage conditions on donkey milk nutritional and hygienic characteristics.
Original title: Effects of pasteurization and storage conditions on donkey milk nutritional and hygienic characteristics.
Martini M., Salari F., Altomonte I., Ragona G., Piazza A., Gori R., Casati D., Brajon G.
Journal of Dairy Research · 2018 · 85(4), 445–448
Research Center “Nutraceuticals and Food for Health” and Department of Veterinary Science, University of Pisa, Italy (according to the authors)
DOI: 10.1017/s0022029918000687
Transparency: funding and conflicts of interest could not be checked from the abstract. No product-related statement for DON DONKEY’S®.
Summarised and checked by the DON DONKEY’S editorial team against the original publication · As of: November 2026
The study summarised above was carried out independently of DON DONKEY’S® and does not relate to our products. It serves solely to inform about the state of research.
DON DONKEY’S® donkey milk and donkey milk powder are foods. They are not intended to prevent, treat or cure any disease and do not replace medical advice.
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DON DONKEY’S® donkey milk
100 % donkey milk · raw milk, frozen
On this page we report the findings of a published study. Independently of that, you will find our donkey milk here: 100 % donkey milk, frozen as raw milk.
100 ml bottle / 100ml · Unit price: €249,00 / 1 l · incl. VAT, plus shipping
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Donkey Milk Powder
Donkey milk in powder form
For anyone who prefers a longer shelf life: our donkey milk in powder form – easy to store and portion.
20g · Unit price: €1.245,00 / 1 kg · incl. VAT, plus shipping