The Maillard reaction (named after the French natural scientist Louis Camille Maillard [ maˈjaʁ ]) is a non- enzymatic browning reaction that can be observed, for example, when deep-frying and frying food. Here, amine compounds (such as amino acids , peptides and proteins ) are converted into new compounds with reducing compounds under the influence of heat . It should not be confused with caramelizing , but both reactions can occur together.
Contrary to what is typically suggested by name reactions , this is not a single specific chemical reaction , but a complex set of many reactions that take place next to one another as well as one after the other, which leads to a large number of reaction products , many of which have not yet been precisely identified were.
In 1913 Louis Camille Maillard published a document describing the reaction of amino acids with glycosides at elevated temperatures. However, it was the American chemist John E. Hodge who worked at the US Department of Agriculture in Peoria, Illinois and published a document in 1953 describing the reaction mechanism of the Maillard reaction.
The Maillard reaction is important for cooking and the food industry , because the brown end products, called melanoidins , have an intense taste and are responsible for the typical aroma and color of roasted , baked and fried foods with a high protein content. The reaction also delays spoilage, since the melanoids / melanoidins, like the pronyl-lysine, bind oxygen in the air. Scientists also determined a weak antibacterial (germ-inhibiting) effect. However, the Maillard reaction can also cause undesirable changes in taste when sterilizing meat or dairy products , for example , and can occur even without exposure to heat when protein-containing foods are stored for a long time. The Maillard reaction can reduce the amino acid content of food by up to 20%, which can be viewed as an impairment .
In the multi-stage reaction , from around 140 ° C, an amino acid is first combined with reducing sugars such as aldoses (e.g. glucose ) or acyloins (e.g. fructose ) with elimination of water . A Schiff base is created , which is rearranged in several steps. A reaction with aldoses leads to an Amadori rearrangement , to acyloins a Heyns rearrangement . The Amadori and Heyns products result in highly reactive alpha-dicarbonyl compounds such as the 1-, 3-, and 4-deoxydicarbonyls known as deoxyosones and many others from them. Cyclic compounds and heterocyclic compounds are sometimes formed . The 1-Deoxyosone can e.g. B. to Nor furaneol (caramel smell ) or maltol (roasted smell) react, while from the 3-Deoxyosonen z. B. furfural (from pentoses ) or 5-hydroxymethylfurfural (from hexoses ) and from 4-Deoxyosonen z. B. maltol or acetylformoin are formed. Further reactions with amine compounds result in z. B. pyrroles and pyridines . Strecker degradation also produces odor-intensive aldehydes such as methional, phenylacetaldehyde , 3- and 2-methylbutanal and 3- and 2-methylpropanal as well as colored compounds known as melanoidins. Furthermore, with the amino acid cysteine, sulfur-containing cyclic reaction products with a characteristic odor, e.g. B. bis-2-methyl-3-furyl disulfide. Under the conditions of anhydrous heat that are conducive to a Maillard reaction, the caramelization of the carbohydrates contained in the food also takes place in parallel to the Maillard reaction . From 180 ° C also begin Verkohlungsprozesse .
Creation of acrylamide
An example of an undesirable Maillard reaction is the increased formation of acrylamide from the amino acids asparagine and glutamine (e.g. in potato and cereal products) at temperatures from 170–190 ° C. This reaction can be reduced by controlling the temperature below the critical temperature. A reduction in the formation of acrylamide from potatoes is also possible by using boiled potatoes and storing them in dark and cooler (6–10 ° C) storage.
Unwanted Maillard reactions lead to numerous other potentially mutagenic and / or carcinogenic compounds. The connections are still partly unclear.
In food production
The Maillard reaction affects the taste, texture, and smell of many foods, including:
- Roasted products such as coffee beans , cocoa beans , malt or onions
- fried foods such as french fries
- Baked goods such as bread , toast or cookies
- fried foods such as steak
Many flavors are produced industrially with the help of the Maillard reaction ( reaction flavors ). A wide variety of flavors are produced from different amino acids and types of sugar in a combination of duration and type of heating. The combination of the amino acid cysteine with the sugar glucose creates the aroma of fried onions when heated for a long time, and the aroma of roast when heated for a short time.
Influencing the Maillard reaction
A number of factors influence the Maillard reaction (rate of formation, proportion of Maillard compounds in the end product). A reduction in the water content and an increase in the protein content, the reducing sugars, the thermal energy, the pH value and / or the time of the reaction have a beneficial effect on the Maillard reaction.
Examples of application:
- Increase in the pH value by lye in the production of lye pastries .
- Reduction of the water content in the bread crust through dry heat.
- Spread egg whites or a sugar solution on biscuits or rolls before baking.
The Maillard reaction plays a role in certain aging processes in the human body and in diabetes mellitus . Here, oxidative reactions lead to damage to the body tissue. In the summer of 2004, however, surprising interim results of an EU study (since 1998) were presented at a conference in Hamburg, which also confirm the antioxidant effects of Maillard products. A group of Italian scientists led by Vincenzo Fogliano from the University of Naples also discovered that melanoidins can counteract the development of metastases .
The Maillard products produced in the laboratory block certain proteins , the lectins , which hold cancer cells together and thus accelerate the formation of metastases. On the other hand, patients with diabetes or kidney dysfunction have an increased melanoidin level . The exact relationships are still unclear here.
- M. Angrick , D. Rewicki: The Maillard reaction . In: Chemistry in our time , 14th year 1980, No. 5, pp. 149–157, doi : 10.1002 / ciuz.19800140503 .
- Franz Ledl, Erwin Schleicher: The Maillard reaction in food and in the human body - new results in chemistry, biochemistry and medicine . In: Angewandte Chemie . tape 102 , no. 6 , 1990, pp. 597-626 , doi : 10.1002 / anie.19901020604 .
- Monika Pischetsrieder : The Maillard reaction of disaccharides and polysaccharides and reactions of glucose in concentrated solutions. Munich 1994.
- Bernd Schäfer: Natural substances in the chemical industry , Spectrum Akademischer Verlag, 2007, pp. 168–173, ISBN 978-3-8274-1614-8 .
- Angelika Bierhaus, Peter Nawroth: RAGE hypothesis - key to understanding chronic diseases . Medical University Clinic and Polyclinic Heidelberg, 2002
- The "fast onion" experiment . ( Memento from July 12, 2013 in the Internet Archive ) Explanation of the acceleration of the Maillard reaction in onion roasting
- Prof. Dr. Dr. Thomas Henle: Human aging - a baking process? On the significance of the Maillard reaction in food and in vivo , July 11, 2013, Food & Health Academy ( SoSe 13), Uni Hamburg Lecture2Go
- Hans-Dieter Belitz , Werner Grosch, Peter Schieberle : Food chemistry . Springer, Berlin 2009. ISBN 978-3-540-69935-4 . Pp. 270-289.
- LC Maillard : Formation of Melanoidins in a Methodical Way. . In: Compt. Rend. . 154, 1912, p. 66.
- CO Chichester (Ed.): Advances in Food Research - Advances in Food and Nutrition Research , Volume 30. Academic Press, Boston 1986, ISBN 0-12-016430-2 , p. 79.
- JE Hodge: Dehydrated Foods, Chemistry of Browning Reactions in Model Systems . In: Journal of Agricultural and Food Chemistry . 1, No. 15, 1953, pp. 928-43. doi : 10.1021 / jf60015a004 .
- Sarah Everts: The Maillard Reaction Turns 100 . In: Chemical & Engineering News . 90, No. 40, October 1, 2012, pp. 58-60.
- Shigeru Hiramoto et al .: Melanoidin, a food protein-derived advanced maillard reaction product, suppresses Helicobacter pylori in vitro and in vivo . In: Helicobacter , 2004 Oct., 9 (5), pp. 429-435, PMID 15361082 .
- Nathan Myhrvold , Chris Young, Maxime Bilet: Modernist Cuisine: The Art and Science of Cooking . The Cooking Lab 2011. ISBN 978-0-9827610-0-7 . Volume 3, pp. 89ff.
- Entry on Maillard reaction. In: Römpp Online . Georg Thieme Verlag, accessed on September 1, 2011.
- Entry on acrylamide. In: Römpp Online . Georg Thieme Verlag, accessed on September 1, 2011.
- influencing the yield and ingredients of the potato. (PDF) Retrieved October 8, 2017 .
- Patricia Ziegler: Happy Birthday Maillard reaction! . Food focus. Archived from the original on July 12, 2013. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved October 25, 2012.
- Patricia Ziegler: The "Fast Onion" Experiment. Food Focus, archived from the original on July 12, 2013 ; Retrieved October 25, 2012 .
- Ralf Liedke: Formation of dicarbonyl compounds during the breakdown of Amadori rearrangement products. Inaugural Dissertation, 1999, pp. 1-16.
- E. Schleicher: The importance of the Maillard reaction in human physiology . (PDF) In: Journal of Nutritional Science , Vol. 30, Number 1, 1991.
- Vincenzo Fogliano: Biochimica degli alimenti ( Memento of May 10, 2006 in the Internet Archive ) (PDF).
- Caffé e antiossidanti: i segreti per una buona salute nascosti in una tazzina? Encanta.it
- Uta Bilow: Is the bratwurst healthier than its reputation? In: Frankfurter Allgemeine Zeitung , September 29, 2004.