HomeFlavor & Fragrance FormulationChallenges in Creating Natural Compliant Reaction Flavors

Challenges in Creating Natural Compliant Reaction Flavors

Luke Grocholl


Food flavor changes as food is cooked, but the chemical change that takes place during cooking was difficult to understand for early chemists until French chemist Louis Camille Maillard elucidated the reaction between sugars and amino acids during heating. He noted that amino compounds such as amino acids and proteins react with reducing sugars under moderate temperatures (typically 100-150 °C) to form melanoid pigments and volatile, fragrant molecules.

This complex reaction, that now bears his name, accounts for the savory taste of cooked meat, baked bread, roasted coffee, and other cooking-related flavors. Since the Maillard reaction also results in melanoid pigments, it accounts for the darkening or browning that occurs during roasting or grilling. Due to the browning effect, these aromas are generally described as brown flavors by the flavor & fragrance industry.

For the flavor industry Maillard browning raw materials offer a significant opportunity. A savory flavor blend added to processed food may consist of amino acids and sugars that make up the core Maillard reaction plus fats, salts, glutamates, non-reactive proteins, and processing aids in addition to flavor chemicals. Combined into a food product, they will provide the savory flavor of cooked meat or baked bread when heated; flavors that may otherwise be lost in the food manufacturing process steps. These materials are also the backbone of flavor found in vegetarian meat substitutes, an important market growing at a rate ~50% faster than other processed foods.2

Plant or microbiologically sourced raw materials of Maillard reaction, often called reaction flavors may meet the requirements of vegetarian labels. For these markets in particular and the food market in general, the natural flavor designation carries significant market value. With their multiple components, Maillard reaction raw materials may be difficult to categorize as natural flavors, however.

The US FDA defines a natural flavor as “the essential oil, oleoresin, essence or extractive, protein hydrolysate, distillate, or any product of roasting, heating or enzymolysis, which contains the flavoring constituents derived from a spice, fruit or fruit juice, vegetable or vegetable juice, edible yeast, herb, bark, bud, root, leaf or similar plant material, meat, seafood, poultry, eggs, dairy products, or fermentation products thereof, whose significant function in food is flavoring rather than nutritional”3. Reaction flavor components (amino acids and sugars) derived from natural sources therefore can be labelled as natural flavors. In order to meet this designation, however, it must be demonstrated that the constituents are consumed during heating or cooking and thus converted completely to flavor. In addition, the other components of a reaction flavor (fats, salts, other proteins, etc.) must be declared separately on the product label.

The USDA also weighs in on labelling. They state a reaction flavor cannot be labelled as natural flavor since it “does not come from a natural source, as such, but is carefully formulated in specific proportions to ensure a product mixture of desired flavor characteristics.”4 This guidance seems to be in contradiction to FDA regulations, however, they do allow for the ingredients in a reaction flavor that are either consumed during heating or meet the FDA definition of flavor to be listed as flavors. These components can be declared natural flavors if they meet the FDA natural definition. Proteins and sugars not consumed when heating as well as fats, salts, processing aids and other components of a reaction flavor must be listed separately on a product label.

As an example of an ingredient list, below is a commercial, vegetarian, chicken substitute with the reaction flavor components highlighted:
Water, Vital Wheat Gluten, Organic Tofu (Water, Organic Soybeans, Magnesium Chloride, Calcium Chloride), Non-GM Expeller Pressed Canola Oil, Organic Cane Sugar, Yeast Extract, Oat Fiber, Vegan Natural Flavors, Non-GM Corn Starch, Sea Salt, Potassium Chloride, Granulated Garlic, Calcium Lactate from Beets, Onion Powder, Spices, Citric Acid, Titanium Dioxide

In the EU, declaration of natural flavor is more complex, however. Although the EU has a clear definition of natural flavors,5 reaction flavors, or “Thermal Process Flavors” are defined separately in the EU code. The EU defines a thermal process flavor as “a product obtained after heat treatment from a mixture of ingredients not necessarily having flavouring properties themselves, of which at least one contains nitrogen (amino) and another is a reducing sugar”6. Additionally, the EU requires flavor molecules to be listed on an approved list7, however, this applies only to flavoring substances, defined chemical substance with flavouring properties.8 Because thermal process flavors are listed as a distinct flavor category from natural flavors in the EU regulations, they are declared as “flavors” or “flavoring” on a label even if they are of natural origin. Natural derived thermal process flavor components can be declared as natural only if they meet the natural flavor definition and are listed in the EU Union List of Flavourings and Source Materials.7

Terms such as “all natural” are important to the flavor industry. Neither the US nor the EU has clear definitions of natural food or natural ingredients, but both regulatory bodies do clearly define natural flavors. Suppliers of raw materials for thermal process flavors, such as Sigma-Aldrich therefore have a challenge. Customers request natural declarations, however, natural origin products may not be listed on the EU Lists. Therefore, we offer these food grade products as “natural sourced” such as Product No. W328512 L-Glutamic acid, ≥99%, FCC, natural sourced, FG. The natural source designation is verified through supplier review and isotopic analysis. Vegan and vegetarian statements can also be provided with these products to verify their status for food industry.


When our customers use these products they can declare flavors as “natural” for the US market, but cannot declare them as a natural flavor in the EU.

An example of a commercial vegetarian bratwurst with the thermal process flavor components highlighted is listed below:
Water, Vegetable Protein 11% (Wheat Gluten, Soy), Onion, Rapeseed Oil, Egg White, Natural Flavouring, Starch (Potato, Tapioca), Dextrose, Salt, Sugar, Herbs and Spices, Colour (Plain Caramel), Mineral (Ferrous Fumarate), Vitamin B12

For other global markets, the designations are not as clear. Where not specifically demonstrated, many food manufacturers rely on IOFI (International organization of the Flavor Industry) guidelines. These guidelines generally follow the EU standards. The IOFI guidelines are similar to the EU regulations. IOFI has guidelines on thermal process flavors distinct from its natural flavor guidelines. Under IOFI reaction flavors are not designated as natural even if they are of natural origin.

With the strong emphasis on clean food labels, and global concerns on food fraud, it is important to understand customer requirements on label designations so we can provide them the necessary information they need to label their products appropriately.


US FDA 21 CFR 101.1.22(a)(3). [Internet]. Available from:
4. [Internet]. Available from:
EC No 1334/2008 art. 3.2(c). [Internet].
EC No 1334/2008 art 3.2(e). [Internet].
EC No 1334/2008 Annex I. [Internet].
EC No 1334/2008 art 3.2(b). [Internet].
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