When a steak browns in the pan, when onions turn golden in the sauté, when bread crust takes on an inviting colour, kitchen science sits behind all of them. The common mistake is to call all of this "caramelization." In truth, two separate reactions are at work, with different rules, different temperatures, different flavours. A cook who manages one well also understands the other; one who cannot tell them apart loses the crust.
This article separates the two reactions cleanly, shows which one runs in which recipe, and corrects the three most common misconceptions.
Two separate reactions: one with proteins, one with sugars
The Maillard reaction was defined in 1912 by the French chemist Louis Camille Maillard in a paper titled "Action des acides aminés sur les sucres: formation des mélanoidines par voie méthodique" (Comptes Rendus de l'Académie des Sciences, 154: 66 to 68). C&EN magazine covered the reaction's 100th anniversary in detail in 2012. Amino acid (a protein building block) and a reducing sugar (glucose, fructose, lactose) react at a specific temperature. The result: hundreds of new aroma molecules and the characteristic browning. A steak, a sauté, a slice of toast, a coffee bean, owe much of their flavour to Maillard.
Caramelization is the pyrolysis of sugar alone. That is, without protein, only sucrose or glucose breaks down with heat, loses water, then re-polymerises. The Wikipedia entry on caramelization documents that in the final stage of the process, three main caramel pigments form: caramelan, caramelen and caramelin. The result is simpler but deep: sweet, slightly bitter, amber colour. The gold of onions (with their high sugar content), caramel sauce in a dessert, the crust of a crème brûlée; all are caramelization.
Modernist Cuisine explains the Maillard reaction in detail for professional kitchens; in most recipes the two reactions run together or in sequence. As meat browns in a pan, Maillard runs on the surface; if active sugar lies at the bottom of the pan, caramelization runs there too; the fond (caramelised pan-bottom liquid) is the combined product of the two.
Temperature window: not the only difference, but the most critical
Maillard starts in the 140 to 165°C range, and gives ideal yield in the 165 to 200°C range. Above 200°C, pyrolysis (burning) begins; polycyclic aromatic hydrocarbons (bitterness plus health risk) form. The WebstaurantStore kitchen guide gives these thresholds as consensus values.
Caramelization starts a little higher: a caramelization basics article explains that sucrose begins to melt and its glycosidic bond starts to break around 160°C. At 170°C light caramel, at 180°C amber and complex aroma, above 190°C scorching (burning).
Water evaporates at 100°C, which means browning does not happen while water is on the surface. That is why blanched vegetables in a pan stay pale; only as the water evaporates do they sauté. As covered in detail in the science of searing meat article: surface stays dry, heat stays high, the pan does not get crowded.
Practical home-kitchen ranges:
- Pan sauté: 180 to 200°C pan surface
- Oven roast: 200 to 220°C, on the upper rack
- Golden onion: 140 to 160°C, low to medium heat
- Caramel sauce: 170 to 180°C, close to bottom sticking
Maillard's aroma universe: why it is so rich
Caramelization produces a handful of molecules, all in the "sweet" family. Maillard is much more complex. According to a Modernist Cuisine analysis, the Maillard reaction produces hundreds of volatile compounds: pyrazines (toasted almond, cocoa), thiazoles (meaty notes), furans (caramel-coffee), Strecker aldehydes (malt-bread), among others. The same reaction, with different amino-acid inputs, yields different aroma profiles.
Beef, lamb, chicken, fish all enter Maillard in the same pan at the same temperature, but the aroma outcomes differ because each meat's amino-acid composition differs. The same is true for bread: sourdough, rye, white flour bring different amino-acid pools, and the crust aromas differ.
The science of searing meat article covers this on the meat side. The myth "we are sealing the surface" is wrong; the real work is Maillard.
Caramelization: the lone journey of sugar
Sucrose melts at 160°C, starts losing water, then gradually darkens. Around 170°C gold, 180°C amber, 190°C dark amber, above 200°C bitter burning. The Laura's Bake Lab caramelization guide shows that in the final polymerisation stage, caramelan, caramelen and caramelin pigments form in sequence. Once the amber colour passes, the sugar underneath is irreversible; constant stirring will not help. Take it off the heat, or drop the moist heat in one stroke.
The "caramelisation" of an onion is not pure caramelisation alone; it is actually Maillard (amino acids inside the onion) plus caramelisation (sugars inside the onion). But because most of the credit goes to the sugar side, the common name is caramelisation. For accuracy, the proper onion sauté guide covers the 7 to 10 minute "golden-coffee" technique most used in practice.
Moisture enemy: why a dry surface is everything
The most common home-kitchen mistake: not checking the dryness of the pan after washing the steak, not patting the oil dry after marinating vegetables, leaving the tray base wet instead of greasing it before onions go in.
A handful of water on the surface locks the temperature at 100°C. The vapour layer insulates between the pan and the food (the Leidenfrost effect), and both Maillard and caramelisation stop. For that reason:
- Dry the meat with paper towel before it touches the pan
- Do not salt vegetables before sautéing; salt draws water and lengthens the cook
- Heat the pan first, then add the oil, then the meat (oil close to smoking)
- Do not crowd the pan; if the vapour cannot escape, everything boils
The oil chemistry and smoke points article shows which oils hold which temperature; choose accordingly.
In practice: which reaction in which recipe
In most Tatonia database recipes, both reactions are at work. The list below shows which is dominant.
Maillard dominant: steak, grilled köfte, oven chicken, roasted bones for soup base, coffee beans, roasted nuts, bread crust, toast.
Caramelisation dominant: caramel sauce, crème brûlée crust, balsamic glaze, sugared fruit, lokum's outer coating.
Mixed (both active): sautéed onion, roasted mirepoix (carrot-onion-celery), the fond of a pan sauce, bone-and-vegetable oven roast.
Wherever Tatonia recipes say "golden" or "caramelised," in truth both reactions are working together. The aromatic vegetable bases (mirepoix, sofrito) article covers this combined base.
Three common misconceptions
1. "If you sear meat, it does not lose juice." Maillard forms a crust on the surface, but the crust is not waterproof; the meat loses water because of the heat anyway. As covered in detail in the science of searing meat, the real work of searing is aroma and texture, not stopping juice loss.
2. "The hotter the heat for sautéing, the better." No. Above 200°C, the crust burns, the outside bitters before the inside cooks, and Maillard's beautiful pyrazines give way to burn products. The temperature window is 165 to 200°C; above that is fast but risky.
3. "Caramelised onion is done in 10 minutes." No. Real caramelised onion (the French onion soup base) is 35 to 45 minutes on low heat with constant stirring. The onion's water goes out fully, then the sugar slowly browns. For those in a hurry, "golden-coffee" (7 to 10 minutes) is enough, but that is not the classic caramelised.
Practical summary
High heat plus dry surface plus single layer plus patient wait: any cook who applies these four rules catches both Maillard and caramelisation. Stopping when the crust reaches deep gold, cooling quickly when it reaches dark brown, is essential. When you see "golden colour," "caramelised," or "until browned" in Tatonia recipes, apply the temperature and moisture rules you have learnt here; the difference shows.
Related Reading
- Et Mühürlemenin Bilimi: how Maillard works on the surface, sear myth and reality.
- Soğanın Doğru Kavrulması: the temperature and time balance of three different techniques.
- Yağ Kimyası ve Duman Noktaları: choosing the right oil for high heat.
Sources
- Louis Camille Maillard biography, Wikipedia: 1878 to 1936 life, and the publication details of the 1912 paper.
- Maillard reaction, Wikipedia: reaction mechanism, stages, history.
- The Maillard Reaction Turns 100, C&EN (2012): American Chemical Society 100th anniversary article.
- The Maillard Reaction, Modernist Cuisine: advanced explanation for the professional kitchen.
- Maillard Reaction Temperatures, WebstaurantStore: 140 to 165°C onset and 165 to 200°C yield range.
- Caramelization, Wikipedia: sucrose pyrolysis and the caramelan, caramelen, caramelin polymers.
- Caramelization, Fond Kitchen: 160°C onset, 170°C light, 180°C amber.
- Caramelization Basics, Laura's Bake Lab: pigment formation and the final polymerisation step.