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Research on donkey milk · Study 117
Aroma: donkey milk powder vs. cow’s milk powder
61 volatile compounds were recorded in cow, donkey, camel and horse milk powders from Xinjiang. Eight of them reliably distinguished donkey and cow milk powder, for example 3-hydroxy-2-butanone (0.55 vs. 5.60 %).
At a glance · swipe or use the arrows
The key figures
Study design
How it was studied
Cow, donkey, camel and horse milk from different regions of Xinjiang (donkey milk from Hotan) was collected in 2022 in three batches (February, June, October) of three samples each and stored frozen. To replicate common commercial processes, cow and camel milk were spray-dried and donkey and horse milk freeze-dried (residual moisture 5–6 % in each case). The volatile compounds were determined by gas chromatography–ion mobility spectrometry (GC-IMS) (2 g powder, 80 °C, triplicate measurement) and given as a relative share of the total signal. For the pairwise comparisons of cow against each other type of milk, PLS-DA models with permutation tests (VIP > 1) were calculated, and the candidates were then checked by ROC analysis (AUC 0.95–1) and Youden index.
Interactive chart · values from the study
Compound groups of the volatile compounds per milk powder
Means from Table 2 (relative shares). The totals are well below 100 % because unidentified signals are not listed.
Second analysis
Markers for distinguishing donkey and cow milk powder
The eight markers confirmed by ROC analysis (section 3.4); values from Table 2. Donkey and cow milk powders were dried differently (freeze-dried and spray-dried respectively).
Results
What the study measured
In total, 108 signals were recorded and 61 of them identified. The four powders were similar in the type of compounds but differed in their amounts; ketones, aldehydes and alcohols formed the main groups. The freeze-dried donkey and horse milk powders showed more signals than the spray-dried cow and camel milk powders.
In the donkey milk powder, the ketone share was 10.83 % compared with 23.41 % in the cow’s milk powder, and the aldehyde share 22.21 % compared with 16.65 %. Hexanal reached the highest single value of all four powders in the donkey milk powder, at 9.02 %.
Typical milk aroma compounds such as 3-hydroxy-2-butanone (0.55 vs. 5.60 %), 2-butanone (1.30 vs. 3.10 %) and 2-heptanone (1.20 vs. 3.51 %) were markedly lower in the donkey milk powder than in the cow’s milk powder; (E)-2-pentenal (1.30 vs. 0.75 %) and 2-methylbutanal (0.55 vs. 0.10 %) were higher.
The PLS-DA model cow vs. donkey gave 15 candidates with VIP > 1 (Q² 0.67). After ROC testing, eight markers remained: (E)-2-pentenal, 2-pentanone, acetone, dimethyl sulphide, 2-butanone, 4-terpineol, 3-hydroxy-2-butanone and 2-heptanone.
For cow vs. camel, six markers remained, for cow vs. horse 19. Horse milk powder stood out, among other things, through (Z)-2-methylpent-2-enal (5.34 %) and 4-terpineol (3.63 %).
Based on the confirmed markers, the authors created GC-IMS fingerprints with which cow’s milk powder can be visually distinguished from the other powders; for donkey vs. cow, they highlighted 2-butanone as a particularly striking feature.
Authors’ conclusion: In the view of Gou et al. (2023), cow, donkey, camel and horse milk powders are similar in the type of their volatile compounds but differ clearly in their amounts. With eight, six and 19 markers respectively and the GC-IMS fingerprints derived from them, the authors saw a basis for detecting admixtures of cow’s milk powder in special milk powders; validation on market samples is still pending.
Critical assessment
Strengths and limitations
Species and drying confoundedClear limitation
Donkey and horse milk were freeze-dried, cow and camel milk spray-dried. Differences between donkey and cow milk powder therefore cannot be attributed reliably to species; the authors themselves attribute the higher ketone content, for example, to spray-drying.
Origin and number of animals unclearClear limitation
Three batches of three samples each were collected per type of milk; the number and breed of animals are not given, and each type of milk comes from a different region of Xinjiang. Whether the markers also apply to milk of other origins was not tested.
Contradictory countsNote
The text mentions 22 dimer signals, Table 2 marks 19; the compound classes given (13 alcohols, 7 esters, 12 aldehydes, 7 ketones, 1 ether, 1 acid, 2 furans) do not add up to 61. Two aldehydes are listed under alcohols in the table. For cow vs. horse, 23 candidates are mentioned but 22 are listed.
Marker counts and labelsNote
The abstract and section 3.4 give 8, 6 and 19 markers; the conclusion says “(E)-2-pentenal and eight others”, “3-methyl-1-butanol and six others” and “2-nonanone and 19 others”, i.e. one more in each case. Section 3.5 describes the comparison in Figure 4c as cow vs. camel instead of cow vs. horse.
Relative shares without a referenceNote
The contents are given as percentages, but the compound groups add up to only about 55–65 % per powder; the reference quantity is not explained. No sensory test was carried out; statements about odour impressions are based on the literature.
Two-stage marker testingStrength
The candidates from the PLS-DA were tested by permutation test and additionally by ROC analysis with thresholds. Table 2 documents all identified compounds with means, spread and significance letters, and the samples cover three seasons.
Editorial assessment: The study describes aroma differences between laboratory powders from Xinjiang and proposes markers for authenticity testing. As donkey and cow’s milk were dried differently, the values describe the combination of type of milk and process; no conclusions about individual commercial products can be drawn from it. To the research archive.
Research question for DON DONKEY’S®
Do the proposed aroma markers detect an admixture of cow’s milk powder even when donkey and cow’s milk have been dried in the same way and contain only small proportions of cow’s milk?
Original publication
Discriminant Analysis of Aroma Differences between Cow Milk Powder and Special Milk Powder (Donkey, Camel, and Horse Milk Powder) in Xinjiang Based on GC-IMS and Multivariate Statistical Methods
Original title of the publication.
Gou Y., Han Y., Li J., Niu X., Ma G., Xu Q.
Foods · 2023 · 12(21), 4036
College of Food Science and Engineering, Corps Key Laboratory of Deep Processing of Specialty Agricultural Products in Southern Xinjiang and Instrumental Analysis Center, Tarim University, Alar, China
10.3390/foods12214036: 10.3390/foods12214036
Transparency: according to the paper, National Natural Science Foundation (31760442), High and New Technology Project of the First Division of Xinjiang Production and Construction Corps (2022GJJ03) and Financial Support for the Construction of Key Disciplines in Food Science and Engineering (130000304). The authors declare no competing financial interests or personal relationships that could have influenced the work. No product-related statement for DON DONKEY’S®.
Summarised and reviewed by the DON DONKEY’S editorial team on the basis of the original publication · as of October 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
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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.
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For anyone who prefers a longer shelf life: our donkey milk in powder form – easy to store and portion.
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