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Can proteins from donkey milk be enclosed in tiny fat droplets? A team from Serbia and Slovenia tested this in the laboratory using so-called nanoliposomes. Only one technical value was measured: what proportion of the protein could be assigned to the droplets after centrifugation. Depending on the concentration, this was around 83.5% or 88.9%.
Laboratory formulation study – without tests on the skin, on cells, or on humans. No statement about an effect in humans. Donkey milk is a food.
Study at a glance
| Feature | Information |
|---|---|
| Original title | Nanoliposome Encapsulation with Donkey Milk Bioactive Proteins and Its Possible Application in Dermatology and Cosmetics |
| Authors | Kocić H., Stanković M., Arsić I. |
| Journal | Acta Facultatis Medicae Naissensis, 34(3): 199–204 |
| Year | 2017 |
| Country | Serbia (University of Niš) and Slovenia (University of Maribor) |
| Study type | Laboratory formulation attempt (in vitro) |
| Sample | Skimmed donkey milk in 1-, 2-, 5- and 10% solution; number of repetitions not stated |
| DOI | 10.1515/afmnai-2017-0021 |
What question did the researchers ask?
Nanoliposomes are tiny droplets with a shell made of phospholipids, which are fat-like molecules. Inside them, they can take up dissolved substances. The authors wanted to know what proportion of the proteins from skimmed donkey milk could be enclosed in this way and whether the concentration of the milk solution played a role.
How it was investigated
- Dissolving: Skimmed donkey milk was prepared in water to make 1-, 2-, 5- and 10% solutions.
- Mixing: Each solution was mixed in a 1 : 2 ratio with a 1% nanoliposome solution (a ready-made product).
- Loading: Two hours in an ultrasonic bath at room temperature.
- Separating and measuring: Centrifuged at 6,500 revolutions per minute and 4 °C, then the protein in the supernatant was determined using the Lowry method, a classic color test for protein.
The results
The encapsulation rate is calculated from the formula (total protein minus protein in the supernatant) divided by total protein times 100. What was no longer dissolved in the supernatant was assigned to the droplets.
| Donkey milk solution | Encapsulation rate | Note |
|---|---|---|
| 1%, 2% and 5% | approximately 83.5% | common value in the paper; summary: "more than 80%" |
| 10% | 88.9% | according to Figure p < 0.001 compared to 1, 2 and 5% |
The study does not include further measurements – such as the size of the droplets, storage stability, or which individual proteins were enclosed.
In the laboratory, approximately 83.5% and 88.9% of the measured protein from skimmed donkey milk was assigned to the nanoliposomes, depending on the concentration. The study does not show more.
Critical assessment
- Only one measured value: There were no tests on the skin, on cells, or on animals. The title only mentions dermatology and cosmetics as possible applications.
- Statistics unclear: The number of repetitions, standard deviations, and the statistical method are not stated – only a p-value in the figure caption.
- Methodological gaps: The duration of the centrifugation is missing, the 1 : 2 mixing ratio is not clearly assigned, and the protein standard for the Lowry measurement is not stated.
- Unknown milk: The origin and processing of the skimmed donkey milk are not described.
- Indirect measurement: Protein that does not appear in the supernatant is assigned to the droplets. Whether it is really inside or just attached to the outside was not tested.
Funding, conflicts of interest, and level of evidence
The paper contains no information about funding or conflicts of interest. The nanoliposomes were obtained as a finished product from a manufacturer. The first author also wrote the skin cell study, which we keep in the archive as Study 32.
Level of evidence: Laboratory formulation attempt (in vitro) – describes a technical property, no statement about effects.
What does this mean for donkey milk as a food?
Nothing can be derived from this study about donkey milk as a food. It describes a technical laboratory step with skimmed donkey milk. The applications in dermatology and cosmetics mentioned by the authors were not investigated; we do not adopt them.
Our research question: Which proteins from donkey milk – such as lysozyme, lactoferrin, or caseins – are enclosed in such processes and which are not? And do follow-up studies fully describe their methods?
Frequently asked questions
What is a nanoliposome?
A very small droplet with a shell made of phospholipids. Such droplets are used in research to enclose substances.
Was a cream with donkey milk tested?
No. The study only measured how much protein could be enclosed in nanoliposomes in the laboratory. A cream or a test on the skin did not occur.
Why is the rate higher at 10%?
The paper describes the difference but does not explain it. Since repetitions and dispersion are not stated, the finding is difficult to assess.
You can find all measured values, interactive graphics, and the complete critical assessment on our research page: Study 80: Donkey Milk Protein in Nanoliposomes. Further studies in the research archive.
Kocić H., Stanković M., Arsić I. (2017). Nanoliposome Encapsulation with Donkey Milk Bioactive Proteins and Its Possible Application in Dermatology and Cosmetics. Acta Facultatis Medicae Naissensis, 34(3), 199–204. DOI: 10.1515/afmnai-2017-0021
Summarized and reviewed by the DON DONKEY'S editorial team based on the original publication · As of: October 2026. This summary does not replace the original work.
End of the study summary. The study was conducted independently of DON DONKEY'S® and does not refer to our products. Our donkey milk is a food.
