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Donkey milk research · Study 171
Donkey milk into powder: what drying does to aromas and proteins
After spray-drying, the enzyme lysozyme in donkey milk retained 58 % of its activity, and β-lactoglobulin fell from 6.43 to 5.51 mg/mL. According to the authors, freeze-drying also affected β-lactoglobulin and lysozyme. In the accelerated shelf-life test, three volatile compounds increased and four appeared for the first time.
At a glance · swipe or use the arrows
The key figures
Study design
How it was studied
Laboratory study by an Italian research group: the profile of volatile compounds (aroma compounds) was determined in fresh donkey milk, after an accelerated shelf-life test, and in freeze-dried and spray-dried donkey milk. For three whey proteins – β-lactoglobulin, α-lactalbumin and lysozyme – total amount, enzymatic activity and thermal stability were measured. Assessed based on the abstract; the full text was not available to the editorial team. Sample numbers, origin of the milk and drying conditions are therefore not stated.
Interactive chart · values from the study
β-lactoglobulin before and after spray-drying
Source: study abstract.
Results
What the study measured
In fresh donkey milk, compounds detected included 2-heptanone, 1,3-bis(1,1-dimethylethyl)-benzene, nonanal, d-limonene, octanoic acid and 1-octanol.
In the accelerated shelf-life test, octanoic acid, 2-heptanone and nonanal increased steadily compared with fresh milk (statistically significant, p below 0.001).
Ethyl octanoate, ethyl dodecanoate, 2-nonanone and 2-undecanone appeared for the first time. The authors consider them suitable markers of donkey milk shelf life.
According to the authors, freeze-drying and spray-drying affected the content of β-lactoglobulin and lysozyme. The abstract gives no individual values for freeze-drying.
After spray-drying, 58 % of lysozyme activity remained and β-lactoglobulin fell from 6.43 to 5.51 mg/mL. The authors attribute this to the high process temperature.
Authors’ conclusion: According to the authors, spray-drying significantly reduced lysozyme activity and β-lactoglobulin content because of the high temperature; the newly appearing volatile compounds may serve as shelf-life markers. The study describes changes in the product – their significance after consumption was not studied.
Critical appraisal
Strengths and limitations
Only the abstract assessedNote
Sample numbers, drying conditions and the values for freeze-drying and α-lactalbumin are unknown.
Accelerated shelf-life testNote
Accelerated storage conditions only approximate normal storage. Whether the markers also appear under everyday conditions remains to be tested.
Product analysis, not a consumption trialClear limitation
Contents and enzyme activity in the product were measured. What remains after digestion is not addressed.
Process details unknownClear limitation
Without details on temperatures and duration, the results cannot simply be transferred to other drying plants.
Two methods compared directlyStrength
The study compares freeze-drying and spray-drying on the same three proteins and also provides a first aroma profile of fresh donkey milk.
Editorial note: The paper shows that the drying method leaves measurable traces in donkey milk, especially with spray-drying. This is a practical pointer for assessing donkey milk powder; no statements on effects in humans can be derived from it. To the research archive.
Research question for DON DONKEY’S®
How do lysozyme activity and β-lactoglobulin in our donkey milk powder compare with the source milk of the same batch – and do these values change over the powder’s storage time?
Original publication
Effects of freeze-drying and spray-drying on donkey milk volatile compounds and whey proteins stability
Original title: Effects of freeze-drying and spray-drying on donkey milk volatile compounds and whey proteins stability
Vincenzetti S., Cecchi T., Perinelli D. R., Pucciarelli S., Polzonetti V., Bonacucina G., Ariani A., Parrocchia L., Spera D. M., Ferretti E., Vallesi P., Polidori P.
LWT – Food Science and Technology · 2018 · 88, 189–195
Italian research group around S. Vincenzetti and P. Polidori; institutional details not included in the research material (country according to author profiles)
DOI: 10.1016/j.lwt.2017.10.019
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.
From our shop
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