Buyer protection
Contents
Fresh and reconstituted donkey milk from freeze-drying powder from 18 Ragusana mares compared: protein 1.62 vs. 1.61%, energy 38.2 vs. 39.0 kcal/100 ml – without significant differences.
Laboratory analysis – no statement about an effect in humans. Donkey milk is a food.
Study profile
| Feature | Information |
|---|---|
| Original title | Comparison of Nutritional Characteristics of Fresh and Freeze-Dried Donkey Milk |
| Authors | Polidori P., Spera M.D., Sabatini A. et al. |
| Journal | Food Science and Nutrition Technology, Volume 4, Issue 1, Article 000172 |
| Year | 2019 |
| Country | Italy |
| Study type | Laboratory study |
| DOI | 10.23880/fsnt-16000172 |
How the study was conducted
In June 2016, milk from the morning milking of 18 multiparous Ragusana donkey mares (7–9 years, 90–100 days after foaling) at a registered farm in Capestrano (Abruzzo) was collected in duplicate. One part was analyzed fresh, the other freeze-dried in a freeze-dryer (Christ Beta 1-16): 1 hour freezing at −45 °C, 48 hours primary drying at 0.10 mbar, 3 hours secondary drying at 5 °C. For comparison, 0.9 g of powder was dissolved in 10 ml of distilled water (90% moisture). Basic composition, energy value (bomb calorimeter), fatty acid profile (gas chromatography), and minerals were determined.
Key figures
| Value | Meaning |
|---|---|
| 18 | Ragusana donkey mares (7–9 years, 90–100 days after foaling), sampling June 2016 |
| 48 h | Duration of primary drying at 0.10 mbar (after 1 h freezing at −45 °C; secondary drying 3 h at 5 °C) |
| 3.1 % | Residual moisture of the freeze-dried powder (dry matter 96.9 %) |
| 73.2 % | Lactose in the powder – largest component, followed by protein 16.1 %, fat 4.48 %, and ash 3.20 % |
| 0.9 g in 10 ml | Amount of powder in distilled water to prepare the reconstituted milk (90% moisture) |
| 1.62 vs. 1.61 % | Protein content fresh vs. reconstituted (not significant) |
| 0.44 vs. 0.48 % | Fat content fresh vs. reconstituted (not significant) |
| 7.08 vs. 7.23 % | Lactose content fresh vs. reconstituted (not significant) |
The results
The freeze-dried powder consisted of 96.9% dry matter with 3.1% residual moisture. The largest component was lactose (73.2%), followed by protein (16.1%), fat (4.48%), and ash (3.20%).
The authors found no significant differences between fresh and reconstituted milk in dry matter (9.56 vs. 9.69%), lactose (7.08 vs. 7.23%), protein (1.62 vs. 1.61%), fat (0.44 vs. 0.48%), and ash (0.42 vs. 0.37%).
The energy value also did not differ significantly: 38.2 kcal/100 ml in fresh and 39.0 kcal/100 ml in reconstituted milk. The authors describe the low energy content as a major limitation for the nutrition of children in their first year of life without suitable supplementation.
No significant differences were found in the fatty acid profile. The most common were oleic acid (26.8 vs. 28.3%), palmitic acid (21.1 vs. 19.3%), and linoleic acid (9.03 vs. 8.22%); EPA was 0.29 and 0.28%, DHA was 0.31 and 0.30% (fresh vs. freeze-dried, respectively).
Among the minerals, calcium was the highest (714.2 vs. 762.3 mg/kg), followed by phosphorus, potassium, chloride, sodium, and magnesium (25.8 vs. 28.6 mg/kg). All differences were not significant.
The authors conclude that the nutritional properties of freeze-dried donkey milk are very similar to those of fresh milk and that freeze-drying can be a useful process to make donkey milk available year-round, as the powder is easy to transport and can be stored without special conditions.
Critical assessment
- Strength – Broad analysis spectrum: Composition, energy value, 17 fatty acids, and six minerals were compared in fresh and freeze-dried milk of the same origin.
- Limitation – One farm, one point in time: All samples come from 18 mares at one farm in June 2016; the text refers to pooled milk samples, but the tables nevertheless state n = 18.
- Limitation – Powder only measured immediately after production: All analyses were performed immediately after freeze-drying. How the powder behaves over a longer storage period was not investigated.
- Note – Inconsistencies in tables: Σ n-6 of the fresh milk (9.57%) does not match the sum of the listed n-6 fatty acids (9.26%); C20:0 (0.68 vs. 1.76%) is marked as not significant despite small standard errors. The unit of the somatic cell count ("29.65 SCC/ml") is probably incomplete.
- Note – Labeling in Table 3: Table 3 says "freeze-dried"; according to the methodology, reconstituted milk was measured.
- Note – Discussion goes beyond the data: Statements in the discussion and conclusion about disease prevention are based on literature and were not investigated in this study.
Funding, conflicts of interest, and level of evidence
The authors state that there are no conflicts of interest.
Level of evidence: Basic research (laboratory) – describes the properties of the milk, no statement about effects in humans.
Our assessment
Laboratory comparison of fresh and freeze-dried donkey milk from one farm; the study describes the composition values of the milk and does not investigate any effects in humans.
Open research question: Do the composition and fatty acid profile of freeze-dried donkey milk powder remain stable over a longer storage period?
You can find all measured values, interactive graphics, and the complete critical assessment on our research page: Study 92: Fresh vs. freeze-dried donkey milk. Further studies in the research archive.
Polidori P., Spera M.D., Sabatini A., Vincenzetti S. (2019). Comparison of Nutritional Characteristics of Fresh and Freeze-Dried Donkey Milk. Food Science and Nutrition Technology, Volume 4, Issue 1, Article 000172. DOI: 10.23880/fsnt-16000172
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 study summary. The study was conducted independently of DON DONKEY'S® and does not refer to our products. Our donkey milk is a food.
