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Contents
In milk from Dezhou donkeys, 1774 lipids and 35 volatile compounds were identified. Between colostrum (day 3) and mature milk (month 3), 233 lipids and 11 volatile compounds differed significantly.
Laboratory analysis – no statement about an effect in humans. Donkey milk is a food.
Study summary
| Feature | Information |
|---|---|
| Original title | Characterization and discrimination of donkey milk lipids and volatiles across lactation stages |
| Authors | Li M., Sun L., Du X. et al. |
| Journal | Food Chemistry: X, 23, 101740 |
| Year | 2024 |
| Country | China |
| Study type | Laboratory study |
| DOI | 10.1016/j.fochx.2024.101740 |
How the study was conducted
Milk samples from twelve Dezhou donkeys (3–5 years, 260–340 kg) from a farm in Shandong, China, were examined: six colostrum samples (3 days after birth) and six mature milk samples (3 months after birth). All animals received the same ration. The lipids were extracted with chloroform/methanol and relatively quantified by UPLC-Orbitrap mass spectrometry; volatile compounds (VOCs) were determined by gas chromatography-ion mobility spectrometry (GC-IMS) using an internal standard. The analysis included OPLS-DA, pathway analysis, odor activity values (OAV), and ROC analysis to distinguish the two lactation stages.
Key figures
| Value | Meaning |
|---|---|
| 12 | Dezhou donkeys (6 each for colostrum and mature milk) |
| 1774 | identified lipid molecules in 30 subclasses |
| 61.95 % | Proportion of triglycerides in the number of identified lipids |
| 70.18 % | Proportion of glycerolipids in the number of lipids |
| 233 | significantly different lipids between colostrum and mature milk |
| 136 | of which lower in mature milk (e.g. 67 TG, 15 PE) |
| 97 | of which higher in mature milk (e.g. 82 TG) |
| 20 | assigned metabolic pathways (KEGG) |
The results
In total, 1774 lipid molecules from six main categories and 30 subclasses were identified. By number, triglycerides dominated (61.95 %), followed by diglycerides (7.67 %), phosphatidylcholines (6.09 %), phosphatidylethanolamines (5.19 %) and sphingomyelins (4.62 %).
Colostrum and mature milk could be clearly separated in the OPLS-DA model. 233 lipids differed significantly: 136 were lower in mature milk (e.g. 67 triglycerides, 15 phosphatidylethanolamines, 13 diglycerides), 97 higher.
The different lipids were assigned to 20 KEGG metabolic pathways; the authors consider the glycerophospholipid, linoleic acid, sphingolipid, α-linolenic acid, and glycerolipid metabolisms to be the most relevant.
Among the 35 identified volatile compounds, aldehydes and ketones each accounted for 28.57 %, esters for 25.71 %, and alcohols for 8.57 %. Ketones made up the largest proportion by quantity; 15 compounds had an odor activity value greater than 1, including methyl-2-methylbutanoate, 2-pentanone, and butyl acetate.
Eleven volatile compounds differed significantly. Ethyl hexanoate, both ethyl acetate signals, and acetone were higher in mature milk (acetone 5292.26 vs. 3479.42), while 2-heptanone, 2-pentanone, 2-butanone-M, and 3-methyl-3-buten-1-ol were higher in colostrum.
In the principal component analysis of the volatile compounds, both stages separated (first component 84.1 %, second 8.1 %). Acetone, 2-heptanone, and ethyl acetate achieved an area under the curve greater than 0.9 in the ROC analysis and are mentioned as possible distinguishing markers.
According to Li et al. (2024), the lipid and aroma profiles of donkey milk differ clearly between colostrum and mature milk; 233 of the 1774 lipids and 11 volatile compounds were different, and in their view, acetone, 2-heptanone, and ethyl acetate are suitable as possible markers for distinguishing the lactation stages. The authors consider this to be basic information for the quality assessment of donkey milk; health effects were not investigated.
Critical assessment
- Limitation – Small groups, different animals: Only six samples from one farm were examined for each stage, and colostrum and mature milk came from different animals according to the methods section. Differences between the stages may therefore also be due to individual animals.
- Note – Relative instead of absolute quantities: The lipids were only relatively quantified by peak areas, and the percentages refer to the number of molecules, not to their quantity. No unit is given for the concentrations of the volatile compounds.
- Note – Counting of aroma substances: The 35 volatile compounds contain monomer and dimer signals of the same substance as well as three unidentified signals; according to the editorial count of Table 2, this corresponds to 26 entries, of which 23 are identified substances.
- Note – Contradictions in the text: The highlights mention nine, the abstract and results 20 metabolic pathways. The abstract mentions ethyl acetate-M as a marker, the results ethyl acetate-D. Higher OAVs for octanal and hexanal in mature milk are described as significant, although their concentrations in Table 2 are not significantly different (p = 0.2430 and 0.1540, respectively).
- Note – Interpretations not tested: The authors' statements about the sweeter taste of mature milk are not based on a sensory test, and the suspected importance of phosphatidylethanolamines for the development of the foal was not investigated. Effects in humans were not the subject of the study.
- Strength – Broad lipid and aroma profile: The combination of high-resolution lipidomics and GC-IMS provides a comprehensive profile. The OPLS-DA model was tested by permutation test, and Table 2 documents all volatile compounds with mean values and p-values.
Funding, conflicts of interest, and level of evidence
National Key Research and Development Program of China (2022YFD1600103, 2023YFD1302004), Shandong Provincial Natural Science Foundation (ZR2022QC130), Shandong Province Modern Agricultural Technology System Donkey Industrial Innovation Team (SDAIT-27), Support Program for Innovation and Technology in Universities of Shandong Province (2023KJ354), Key Technology Research and Development Program of Shandong (2021TZXD012), and Innovation and Entrepreneurship Training Program for College Students (CXCY2024273).
The authors declare that there are no competing financial interests or personal relationships that may have influenced the work.
Level of evidence: Basic research (laboratory) – describes the properties of milk, no statement about effects in humans.
Our assessment
The study analytically describes which lipids and volatile compounds are detectable in raw milk from Dezhou donkeys and how they differ between two lactation stages. Statements about taste, effect, or individual trade products cannot be directly derived from this.
Open research question: Can the differences between colostrum and mature milk also be detected in the same animals and in a tasting?
You can find all measurements, interactive graphics, and the full critical assessment on our research page: Study 99: Lipids and aroma substances: Colostrum vs. mature donkey milk. Further studies in the research archive.
Li M., Sun L., Du X., Zhao Y., Ren W., Man L., Zhu M., Liu G., Khan M.Z., Wang C. (2024). Characterization and discrimination of donkey milk lipids and volatiles across lactation stages. Food Chemistry: X, 23, 101740. DOI: 10.1016/j.fochx.2024.101740
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 by DON DONKEY'S® and does not refer to our products. Our donkey milk is a food.
