Maillard: an unwanted reaction

Maillard: an unwanted reaction

The Maillard reaction and the compounds it produces (AGEs) are well-established as significant contributors to physiological ageing and “inflamm-ageing” in humans (age-related chronic low-grade inflammation)[1]. The Maillard reaction isn’t desirable for our dogs either.

As I was cooking a beef scramble for the dogs recently, I thought how the (lack of) colouring on the meat might horrify the chefs amongst us. No deep browning, no dark crispy bits. I wanted their meat to be cooked, but not seared.

Never mind Instagrammable food. That unappetising greyish-brown is precisely what I was looking for.  In this dog kitchen, instructions to “brown really well on all sides” are taboo.

Cooking meat and browning meat are not quite the same thing. That distinction matters.

     

     

As meat is cooking, heat alters its pigments and hence its colour. The deeper brown crust, roasted aroma and savoury flavour produced when a relatively dry surface meets high heat come largely from Maillard reactions. These reactions can make food more appealing to cooks, but they don’t make it more nutritious. In food prepared for a dog, there is usually no reason to pursue them.

What is a Maillard reaction?

Maillard browning is not the same as making food safe to eat. Meat can be thoroughly cooked without acquiring a dark crust, particularly when it is cooked with moisture. Which is why slow cooking, poaching and steaming are unlikely to brown food and are safer – in a canine Maillard context – than frying, grilling, roasting or baking.

“Dry the beef thoroughly in paper towels before you brown it,
for it will not brown if it is damp.”
Julia Child in Mastering the Art of French Cooking

Potentially carcinogenic compounds can be formed when meat, poultry or fish are cooked at high temperatures above 150 °C. Because their formation is temperature-dependent, higher temperatures increase the likelihood of their presence[2]. The relationship between time and the Maillard reaction is also important in food preparation[3].

Heat, time and low moisture

So we know that heat, time and low moisture are important for the Maillard reaction. In fact, it isn’t a single reaction but a chain of chemical changes beginning when sugars are reduced or other reactive carbonyl compounds interact with amino groups in proteins.

As Maillard chemistry progresses, it produces a wide range of Maillard reaction products. These include advanced glycation end-products, or AGEs – now well-documented as being damaging to health – as well as other compounds that create the aromas, flavours and brown pigments that humans associate, for example, with roasted or barbecued meat.  The extent of Maillard damage depends on ingredients, moisture, temperature and duration of cooking or processing.

I’ve already written about AGEs in commercial food[4]. Recent pet food analyses confirm that exposure is real and highly variable. AGEs physically alter tissue proteins and actively trigger immune receptors to drive sterile inflammation. In 2022, researchers measured Maillard reaction products in 53 commercial pet foods and treats, with concentrations differing markedly both within and between food types.

Maillard reactions are not simply “a kibble problem”. Thermal food canning processes, drying treats, rendering ingredients, extrusion and repeated heating can all produce different mixtures of reaction products. And browning food for our dogs in the kitchen can produce the same compounds.

Research

AGEs bind to long-lived structural proteins like collagen and elastin. This stiffens blood vessels, reduces skin elasticity and impairs joint cartilage. There is now direct evidence that processing-related AGE exposure can be reflected in dogs’ bodies. But while scientists can measure that dogs absorb these compounds and show changes in blood or urine markers after eating certain processed foods, no long-term feeding trials have investigated whether dietary AGEs directly cause specific diseases in dogs. That said, Maillard reactions are never nutritionally neutral: they can reduce usable lysine, create AGEs and other reaction products and alter dogs’ measurable exposure to them.

As usual, human studies are way out in front. Much of the concern around AGEs and inflamm-ageing comes from human clinical work and rodent studies, rather than definitive canine-specific disease data.

One recent human study noted: “For our own health, it is necessary to be aware of the toxic risks of AGEs, understand the importance of healthy diet and habits, and minimize the risk of diabetes, cardiovascular complications, and other glycation-related diseases”[5].

And one foundational canine study, published as far back as 2014[6], had already pinpointed the need for further research into the long-term health implications, precisely because of the quantity of Maillard compounds pets consume daily in commercial products. For example, the authors estimated dogs’ daily intake of HMF, a Maillard reaction product, at more than 100 times higher than that of adult humans, when adjusted for metabolic body weight.

Cooking without chasing the crust

None of this is an argument against cooking. Cooking improves microbial safety and can improve digestibility. The practical point is much narrower: there is no nutritional reason to brown food for a dog merely because human recipes call for ‘colouring on the meat’.

For the minced beef scramble, breaking the mince apart and allowing some moisture to remain limits surface browning. The eggs were added once the meat was almost cooked and then the mixture cooked through, not at too high a heat and not for too long. The result may look less glamorous than if the meat were cooked for longer or at a higher heat, but the dog does not need the crust. And unnecessary Maillard damage is avoided.

Training treats are another example. “Bake until golden brown” describes a colour and flavour that humans want, not a nutritional benefit. Treats need to cook through in the oven, but allowing them to darken simply drives Maillard chemistry further. Dark edges add nothing. So if your treats look as if they might be catching, cover them with foil or better yet, cook in a mould with an appropriate lid on them to be on the safe side.

A useful canine cooking precaution:
Treat the beginning of charring as a red flag, a warning that excessive heat has triggered chemical reactions and the formation of unwanted compounds.

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References

[1] El Hosry, L., Elias, V., Chamoun, V., Halawi, M., Cayot, P., Nehme, A., & Bou-Maroun, E. (2025). Maillard Reaction: Mechanism, Influencing Parameters, Advantages, Disadvantages, and Food Industrial Applications: A Review. Foods, 14(11), 1881. https://doi.org/10.3390/foods14111881
[2] Nadeem HR, Akhtar S, Ismail T, Sestili P, Lorenzo JM, Ranjha MMAN, Jooste L, Hano C, Aadil RM. Heterocyclic Aromatic Amines in Meat: Formation, Isolation, Risk Assessment, and Inhibitory Effect of Plant Extracts. Foods. 2021 Jun 24;10(7):1466. doi: 10.3390/foods10071466. PMID: 34202792; PMCID: PMC8307633. https://pubmed.ncbi.nlm.nih.gov/34202792/
[3] Tamanna N, Mahmood N. Food Processing and Maillard Reaction Products: Effect on Human Health and Nutrition. Int J Food Sci. 2015;2015:526762. doi: 10.1155/2015/526762. Epub 2015 Jan 8. PMID: 26904661; PMCID: PMC4745522. https://pubmed.ncbi.nlm.nih.gov/26904661/
[4] https://www.doggydelly.com/ages-a-very-apposite-acronym/
[5] Peng, Huan & Gao, Yuqi & Zeng, Chenye & Hua, Rui & Guo, Yannan & Wang, Yida & Wang, Zhao. (2024). Effects of Maillard reaction and its product AGEs on aging and age-related diseases. Food Science and Human Wellness. 13. 1118-1134. 10.26599/FSHW.2022.9250094.
[6] van Rooijen C, Bosch G, van der Poel AF, Wierenga PA, Alexander L, Hendriks WH. Quantitation of Maillard reaction products in commercially available pet foods. J Agric Food Chem. 2014 Sep 3;62(35):8883-91. doi: 10.1021/jf502064h. Epub 2014 Aug 20. PMID: 25088431. https://pubmed.ncbi.nlm.nih.gov/25088431/

Want to know more? These studies might be useful:

• Bridglalsingh, S., Archer-Hartmann, S., Azadi, P., Barbier de La Serre, C., Remillard, R. L., Sunvold, G. D., & Bartges, J. W. (2024). Association of four differently processed diets with plasma and urine advanced glycation end products and serum soluble receptor for advanced glycation end products concentration in healthy dogs. Journal of Animal Physiology and Animal Nutrition, 108(3), 735–751. https://doi.org/10.1111/jpn.13927
• Kocadağlı, T., Clarke, C., & Gökmen, V. (2026). A comparative analysis of Maillard-derived α-dicarbonyl compounds and advanced glycation end products in fresh, wet, kibble, and freeze-dried dog foods. Journal of Animal Physiology and Animal Nutrition, 110(3), 417–426. https://doi.org/10.1111/jpn.70053
• Oba, P. M., Hwisa, N., Huang, X., Cadwallader, K. R., & Swanson, K. S. (2022). Nutrient and Maillard reaction product concentrations of commercially available pet foods and treats. Journal of Animal Science, 100(11), skac305. https://doi.org/10.1093/jas/skac305
• Yamka, R., Sires, R., Wakshlag, J., & Huson, H. J. (2025). Serum metabolomics of senior dogs fed a fresh, human-grade food or an extruded kibble diet. Metabolites, 15(10), 676. https://doi.org/10.3390/metabo15100676

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Important Considerations:

• Always consult your veterinarian before making any significant dietary changes, particularly where there are pre-existing health conditions or dietary restrictions.
• If you are feeding commercial food, check the label for ingredients before giving more. Excessive intake of any foods can have adverse effects.
• Ensure (where possible) that you use high-quality, organic products specifically formulated for pets (or better still, human grade ingredients) to avoid any potential adverse effects.
• Introduce new foods gradually to avoid adverse effects such as gastrointestinal upset or diarrhoea.
• I provide nutritional information purely as a helpful guide. Nutritional information on ingredients is obtained from the US Department of Agriculture’s FoodData Central site (https://fdc.nal.usda.gov/index.html) and any nutritional information provided in recipes is based on an online calculator: calories and other information will vary based on brands, ingredients and other factors.
• Check nutrient levels and recommendations for your dog’s weight, age and activity. For example this nutritional guideline produced by FEDIAF.
• I am not a professional canine nutritionist but supporting research is cited.
• The recipes shared were created by me and tested in my kitchen – and tasted and approved by our doggy friends!