Food Browning by Maillard Reaction

When you chopped onion and fried on pan, and added the onions together with a pinch of baking soda did anybody taste of the browned onions are remarkably sweet and caramel-like, and compared with conventionally browned onions, they were softer!

When you cook meat have you wondered why the meat changes color at different stages of cooking?

But this was observed 102 years back itself by Louis-Camille Maillard.

The browning of these food stuffs is due to Maillard Reaction / Non enzymatic browningas part of his PhD thesis in the year 1912 and are therefore known as the Maillard reaction. Browning, or the Maillard reaction, creates flavor and changes the color of food, the taste and color to baked bread and even the turning of beer brown. Maillard reactions generally only begin to occur above 285°F (140°C). Until the Maillard reaction occurs meat will have fewer flavors. High-temperature processes in particular, such as frying, roasting, grilling, and baking, rely heavily on the Maillard reaction for the characteristic aromas it produces.

Maillard browning is a chemical reaction that usually occurs between amino acids (the building blocks of protein) and those carbohydrates known as reducing sugars – although the reaction has been known to occur between reducing sugars and whole proteins. In a Maillard reaction, the reactive carbonyl group of a reducing sugar molecule reacts with the nucleophilic group of an amino acid, causing a change in color (usually darkening of color) and flavor of a food product. Heat (energy) is usually required for a Maillard reaction to proceed. Reactions between reducing sugars and free amino acids occur easily and with very little heat required. Reducing sugars will also easily react with the reactive terminal end amino acids of hydrolyzed proteins and, again, very little heat is required.

Reactions between reducing sugars and amino acids that are part of a whole protein are less common and require more heat (energy) to proceed. In the food industry, the troublesome Maillard reactions that occur over shelf life time are usually those reactions between reducing sugars and free amino acids or small peptides that result from protein hydrolysis that occurred during food processing. The visible result of a Maillard reaction is development of a darker color called browning. A flavor change usually accompanies the development of the darker color.

Products with Maillard reactions

The Maillard reaction is responsible for many colors and flavors in foodstuffs:

• Caramel made from milk and sugar

• The browning of bread into toast

• The color of beer, chocolate, coffee, and maple syrup

• The -tanning products

• The flavor of roast meat

• The color of dried or condensed milk

• 6-acetyl-1,2,3,4-tetrahydropyridine is responsible for the biscuit or cracker-like odor present in baked goods like bread, popcorn, tortilla products.

• 2-acetyl-1-pyrroline flavours aromatic varieties of cooked rice. Both compounds have odor thresholds below 0.06 ng/l.

Amino Acids

Amino acids are biologically important organic compounds composed of amine (-NH2) and carboxylic acid (-COOH) functional groups, along with a side-chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids. Since 2001, 40 non-natural amino acids have been added into protein by creating a unique codon (recoding) and a corresponding transfer-RNA: aminoacyl — tRNA-synthetase pair to encode it with diverse physicochemical and biological properties in order to be used as a tool to exploring protein structure and function or to create novel or enhanced proteins.

Experts classify amino acids based on lots of different features. One of them is whether or not people can acquire them through the diet. According to this factor, scientists recognize 3 types: the nonessential, essential, and conditionally essential amino acids. Those 8 called essential (or) indispensable can’t be produced by the body and therefore should be supplied by food: Leucine, Isoleucine, Lysine, Threonine, Methionine, Phenylalanine, Valine, and Tryptophan. One more amino acid, Histidine, can be considered semi-essential, as the human body doesn’t always need dietary sources of it.

Nonessential ones are produced by the human body either out of the essential ones or from normal proteins breakdown. These include Asparagine, Alanine, Arginine, Aspartic acid, Cysteine, Glutamic acid, Glutamine, Praline, Glycine, Tyrosine, and Serine.

One more classification depends on the side chain structure, and experts recognize 5 types in this classification:

1. Sulfur (Cysteine and Methionine)

2. Neutral (Asparagine, Serine, Threonine, and Glutamine)

3. Acidic (Glutamic acid and Aspartic acid) and basic (Arginine and Lysine)

4. Alphatic (these include Leucine, Isoleucine, Glycine, Valine, and Alanine)

5. Aromatic (these include Phenylalanine, Tryptophan, and Tyrosine)

Amino acids also classified based on structure of the side chain that divides the list of twenty into 4 groups, two of which are main groups and two are subgroups: non-polar, polar, acidic and polar, basic and polar. For example, side chains having pure hydrocarbon alkyl or aromatic groups are considered non-polar, and their list includes Phenylalanine, Glycine, Valine, Leucine, Alanine, Isoleucine, Proline, Methionine, and Tryptophan. If the side chain contains different polar groups like amides, acids, and alcohols, they are classified as polar. Their list includes Tyrosine, Serine, Asparagine, Threonine, Glutamine, and Cysteine.

Further classification goes for acidic-polar (includes Aspartic Acid and Glutamic Acid), if the side chain has a carboxylic acid, and basic-polar (includes Lysine, Arginine, and Histidine), if the side chain contains an amino group.

How to eliminate the negative effects of the Maillard reaction?

Acrylaway is an enzyme that cannot be seen or tasted in the food. It can only be measured through advanced laboratory equipment. During the Maillard reaction, the asparaginase Acrylaway can reduce the mitigation of acrylamide by up to 90 per cent, and can be used in a broad range of foods such as biscuits, cookies, crackers, French fries, crisp and toasted bread, fried and baked snacks, and breakfast cereals – without changing the taste or appearance of the product.


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