About Maillard Reaction:

• It was named after the early 20th-century French scientist Louis-Camille Maillard.
• It is a chemical process that occurs when amino acids, which are the building blocks of proteins, and sugars are heated. The process affects the flavours, aromas, and textures of foods. 
• This reaction is a form of non-enzymatic browning of food, which means that the colour change occurs without the activity of enzymes. 

How does the Maillard reaction cause browning of food? 

• It is a complex chemical mechanism that leads to the formation of multiple products through the process. Chemist J.E. Hodge in 1953 was the first to break down the reaction into steps for simplification. 
  • A variety of foods, including meats, bread, vegetables, coffee beans etc., contain both sugars and protein units.
  • When food is heated, these sugars and proteins undergo a condensation reaction to form a protein-sugar compound called unstable Schiff base.
  • When the Schiff base is rearranged and dehydrated, various intermediate compounds form. These compounds react further to produce important flavour compounds and contribute to the development of characteristic aromas in the food. 
  • Some of the intermediate compounds undergo a rearrangement, which results in the reorganisation of the atoms in the Schiff base, creating a more stable product. These products are important precursors for melanoidins, which are responsible for the brown coloration of the food. 
  • These compounds undergo further changes like condensation and polymerisation, leading to the formation of melanoidins — nitrogen-containing compounds that give food the distinct brown colour. 
• Factors affecting the reaction
  • The rate and extent of this reaction depend on several factors, including temperature, acidity, moisture content, and the types and concentrations of proteins and sugars in the food.
  • Ideal Temperature: These are in the range of 110 degrees C and 170 degrees C, and temperatures higher than that can burn the food and render bitter flavours. 
  • Generally, higher temperatures accelerate the reaction while acidic conditions and the presence of water can inhibit it.
  • This is the reason that foods brown more quickly at higher temperatures and dry foods, such as bread crusts, can develop a deep brown colour during baking.