Donkey milk research · Study 173

Freezing and heating: how stable donkey milk whey proteins remain

When donkey milk was heated to 85 °C, lysozyme fell by 60 % and β-lactoglobulin by 87 %. Lactoferrin was no longer detectable after heat treatments above 65 °C. Below 85 °C and in frozen milk, lysozyme was at a similar level to raw milk and colostrum.

Important: A laboratory study on processing. It measures protein contents in the milk and says nothing about any effect in humans.

At a glance · swipe or use the arrows

The key figures

−87 %β-lactoglobulin after heating to 85 °C

−60 %lysozyme after heating to 85 °C

above 65 °Clactoferrin no longer detectable

below 85 °Clysozyme at a similar level to raw milk

4sample types: colostrum, raw, frozen and heated milk

3whey proteins: lysozyme, lactoferrin, β-lactoglobulin

Colostrumhighest contents of lactoferrin and β-lactoglobulin

1author of the study

2018year of publication, International Journal of Dairy Technology

Study design

How it was studied

Laboratory study from Turkey: colostrum, raw milk, frozen milk and donkey milk heated at various temperatures up to 85 °C were analysed for the concentrations of the whey proteins lysozyme, lactoferrin and β-lactoglobulin. Assessed based on the abstract; the full text was not available to the editorial team. Sample numbers, temperature steps, holding times, freezing conditions and absolute concentrations are therefore not stated.

Laboratory study

Study typeTechnology study (laboratory)CountryTurkeyYear2018JournalInt J Dairy Technol

Interactive chart · values from the study

Decrease in whey proteins at 85 °C

Source: study abstract. Lactoferrin was no longer detectable above 65 °C.

Results

What the study measured

Samples heated to 85 °C showed the greatest loss of stability.

At 85 °C, lysozyme content fell by 60 % and β-lactoglobulin by 87 %.

Lactoferrin had disappeared completely after heat treatments above 65 °C.

Colostrum contained the highest concentrations of lactoferrin and β-lactoglobulin.

Lysozyme was present at similar concentrations in colostrum, raw milk, frozen milk and milk heated below 85 °C.

Authors’ conclusion: According to the study, heat above 65 °C eliminated lactoferrin, and at 85 °C lysozyme and β-lactoglobulin fell markedly; freezing did not change lysozyme. The paper describes protein contents – what they mean for the body was not studied.

Critical appraisal

Strengths and limitations

Only the abstract assessedNote

Sample numbers, temperature steps, holding times and absolute values are unknown without the full text.

Support from a dairy farmNote

According to the publication data, the work was supported by the founder of a Turkish donkey dairy farm. Conflicts of interest could not be checked.

One author, one sourceClear limitation

The study comes from a single author; origin and number of animals are not stated. Independent replication is missing.

Content, not effectClear limitation

Protein concentrations in the milk were measured, not their behaviour during digestion.

Several treatments comparedStrength

Freezing and several temperature steps were compared on the same three proteins, with colostrum and raw milk as reference.

clear limitationnotestrength

Editorial note: The study shows a clear temperature dependence: lactoferrin reacted above 65 °C, lysozyme only markedly at 85 °C. Freezing did not change lysozyme in this experiment. Without the full text, the exact experimental conditions remain open. To the research archive.

Research question for DON DONKEY’S®

Do lysozyme, lactoferrin and β-lactoglobulin in our frozen donkey milk remain at the level of fresh milk from the same batch after thawing?

Laboratory studyWhey proteinsHeat treatment

Original publication

Effect of different treatments on the stability of lysozyme, lactoferrin and β‐lactoglobulin in donkey's milk

Original title: Effect of different treatments on the stability of lysozyme, lactoferrin and β‐lactoglobulin in donkey's milk

Ozturkoglu-Budak S.
International Journal of Dairy Technology · 2018 · 71(1), 36–45

S. Ozturkoglu-Budak, Turkey; institutional details not included in the research material (country according to author profile)

DOI: 10.1111/1471-0307.12380

Transparency: according to the publication data, supported by the founder of a Turkish donkey dairy farm. 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

End of the study summary

Note on our products

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

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.

Transparency: The study examined milk from another herd – not the milk from our partner farms.

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Donkey Milk Powder

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For anyone who prefers a longer shelf life: our donkey milk in powder form – easy to store and portion.

Transparency: The study did not examine our donkey milk powder.