Flavour plays an important
role in life. It stimulates
salivary flow and acid digestion,
and can influence
the metabolism.

What is a flavor and what is its function?
Our ability to perceive flavors and textures while eating and drinking serves not only a physiological but also a social function. These basic sensations are an interaction: direct, indirect and even through space time by triggering images and emotions from the depths of our memories. Who has not felt a certain déjà-vu when a familiar smell carries us back to the good or maybe bad experiences of our childhood?

The sense of smell is the earliest identified sense in humans. When compared this sense’s development to other animals, the human is significantly more evolved. A person has over 1000 taste buds located on the tongue and oral cavity while a dog, for example, has only about 400.

Our sense of smell can distinguish the basic trends of salty, sweet, sour, bitter and the savory richness of umami. Allowing us to distinguish between thousands of individual flavors and combinations of harmonious mixes.

The real perception and differentiation of flavor does not occur directly in the mouth but in the nose. This is why people, who by either natural or accidental causes have lost the sense of smell also lose their sense of taste. Without the sense of smell, eating and drinking lose a pleasant sensation. The alluring and robust aroma of a cup of well-toasted coffee becomes a dull and acid warm liquid in the mouth.

What is usually understood as flavor is the combination of both taste and smell, layered with information about texture and temperature detected in the mouth.

The word “aroma” (flavor) originated from Greece and originally meant spice, seasoning. Today the word aroma is understood as an olfactory sensations arising from various natural products. Flavors are really complex mixtures of volatile substances perceived by the olfactory and gustatory organs. The smell of apple for example comprises more than 300 different aromatic substances.

As the sense of smell the earliest developed it is also one of the most essential and important for survival. It aids in the differentiation between edible and rotten food. Olfactory information is transmitted immediately, requiring only two synapses. The autonomic nervous system is closely involved in the olfactory perception and response of the body to a flavor, which is the reason why foul odors could cause from repulsion response of vomiting while pleasant scents could stimulate secretion of saliva and an increase of appetite.

Beginning of the industrial production of flavors
Preservation of food increases the likelihood of pleasant olfactory sensations while eating and drinking. This has led to the use of smoke, herbs and spices as well as preservatives and flavoring elements when preparing food. For centuries, saffron, anise or pepper together with figs and dates were valued objects of trade between peoples from distant regions. Eventually the commercialization of such plants took place. Techniques to isolate the effective and aromatic ingredients followed.  Through which the art of distillery was developed to obtain the essential oils harnessed initially for perfumes and medicine.

The development of the ethanol extraction opened a broad range of possibilities in the production of flavors. The increase in demand, shortage of raw materials and therefore high production costs encouraged new techniques and methods to obtain aromatic substances. There is no longer a need to extract such substances directly from the plant. Synthesis of the aromatic additives can be created through chemical reaction using organic or even inorganic materials as is seen in vanillin production from lignin.

The role of flavors in our life
The advent of industrialization not only changed the way people work and produce consumer goods but also the way people socialize, and likewise, the way people feed and nourish themselves. Industrial production of food not only created mass-consumption but also achieved a profound transformation of what we eat at home, by bringing more variety and novelties to the daily table.

No one disputes the fact that home-cooked food using fresh ingredients tastes better than industrially processed food. In addition, today fewer and fewer people have enough time for the regular meal preparation. This phenomenon is increasing. Therefore consumption of convenience products is an option. Consumer demands is expected to remain consistent: food must always be available and be delicious. The home-cooked meal is consumed, in most cases, shortly after its preparation. On the contrary, industrially prepared food has a long way to go before being consumed by the final consumer. During storage of raw materials, cooking, transport, storage of the final product and sale time the original aromas are often lost or greatly altered. For this reason additional aromas take on an important role. The term “aroma” also designates food additives intended to provide specific flavors to foods. These products are developed by the flavor industry for the food industry. Flavors are sold in high concentrations, cannot be used directly for human or animal consumption and are legally used as ingredients and regulated as additives. The few flavors that can be found in retail business have a very low concentration and are intended for domestic use.

Modern market trends and consumer expectations are moving towards products that are more natural, functional, healthy and easy to prepare. But not all flavors that the food industry uses can be natural or stem from natural sources or extracts due to the scarcity of the raw materials, their heterogeneous quality, or because of their intrinsic nature, leading to high prices. Thanks to modern biotechnological processes using microorganisms or enzymes it is, however, possible to obtain more natural aromatic substances from a wider range of natural raw materials.

Functionality refers to the quality of offering and benefit beyond satiating appetite or quenching thirst; functional products add benefits such as promoting the health, improving general welfare, having special flavors and textures or helping to maintain a specific diet. Many of the raw materials used in functional products originate from natural sources but this fact does not guarantee a pleasant taste. Peptides for higher protein intake for athletes or even cancer patients taste bitter and the n-3 polyunsaturated fatty acids (omega-3 fatty acids) smell rancid and fishy. Similarly, low fat products have less taste and textural appeal, since fat is an important flavor carrier. In order to make functional products edible, the technological help of aromas is needed.

Due to different flavor applications - foodstuff for humans and animals, drinks and tobacco, medicines, different types of matrices, such as creams, foams, liquids, gels, have different aspects such as textures, viscous, homogeneous or granular. This results in various flavor presentations: from powder formulations, pasty, granular to liquid, the latter being the most used. For simplified measurement and fast homogenization the use of carrier substances such as ethanol, propylene glycol or starch are required. Some flavors also contain additives for technological reason, for example antioxidants or preservatives to prevent premature rancidity and extend shelf life.

Healthy aspects
One of the most controversial issues around flavors is the health aspect. Many people are skeptical and even have a negative opinion about the use of flavorings in food. It is contemplated as a legal but undesirable way to manipulate the authentic quality of the final product by adding substances that were not originally part of the raw materials and because they are not also necessary in homemade food, neither should be in industrial food.

It is true that not all flavorings used in industrial production have an equivalent in nature, as it is in the case of ethyl vanillin, an aromatic substance 2 to 4 times more intense than the vanillin found naturally in vanilla pods. However, there are two important aspects to take into consideration when responding to concerns about flavorings in processed food. Despite the direct and substantial influence that a flavor has on the overall impression of a foodstuff, the amount of flavor needed to modify the taste of a food is surprisingly insignificant, hence the presence of flavoring substances account for only 0.01% to maximum 0.02% of the weight of the final product. Another aspect to take into account is that a flavor over dose is not possible. Should a quantity greater than that recommended by the flavor manufacturer be used the final product would be unpalatable. Even so some flavor substances change their olfactory and gustatory qualities depending on the concentration.

It should also be noted that approximately 2,500 flavoring substances have been used for decades without notable detriment to public health. These have been re-examined scientifically under consideration of toxicological, ecological and even job security and transportation aspects to reach a general and more certain consensus about the safety of the permitted flavor substances in the regulated market. This is the foundation for the development of the well-known "Union List", which applies in the European Union and potentially will also be accepted by the Swiss legislation in the context of drafting the new flavor regulation. The minimal purity that is required in a substance to be used as a flavoring is also regulated in this Union List.

A number of herbs and spices contain naturally aromatic compounds, which are toxic in large quantities. These include for example coumarin, found in cinnamon, or pulegon, found in mint. In order to continue the use of these natural sources the law also regulates the maximum amount of these toxic substances allowed in spices and in their extracts. Similarly, the law regulates the amount and the type of pesticides, heavy metals and chemicals for disinfection and cleaning that can and cannot be present in a flavor. The company must subject the raw materials to quality control (QC).

Each flavor company subjects their raw materials and finished products to strict QC to ensure that only safe goods reach the end consumer. These among other aspects support the conclusion that there is an insignificant health risk in industrial flavorings currently produced.

Flavors are also strongly associated with the onset of allergies and pseudo-allergies. Allergies triggered by food is an overreaction of the immune system to very small amounts of a food, in this case acting as an allergen, which stimulate the formation of antibodies in the blood (immunoglobulin E). In the presence of the allergen the antibodies are attached to this and cause the typical allergic reactions such as redness, swelling, itching till nausea, vomiting and dyspnea. In surveys, 20% of the Swiss population claim to be allergic to food. However, in only 2-8% of cases can be truly detected.

The most frequently allergens are long molecules like proteins, founded for example in gluten, nuts or eggs. Most of the flavor substances, due to their volatile character, are too small to trigger an allergic reaction. If there is a real allergic reaction produced by flavor substances this accounts for a minute portion of the food allergy total.

By a pseudoallergy the mass cells of the body react to certain food ingredients with an excretion of messenger substances, without specific formation of antibodies that can then be detected in the blood. The symptoms are similar to one of a genuine allergic reaction. Pseudoallergies, in contrast to a food allergy, can also be triggered by small molecules. However, the allergic reaction takes place only if a minimum quantity of the allergen is present. That distinguishes a pseudo-energy from a real allergy. And the reaction threshold is different for each person. This is the reason why the presence of the allergen does not always induce an allergenic reaction so long as the threshold quantity has not been reached to induce a reaction. Since aromas are used in very low concentrations, the risk of a reaching this level is very low.

About the author

XImena Aebi-Diaz

Ximena Aebi has a Bachelor in Chemical Engineering and a Master of Food Engineering ETH. She is currently working as a regulatory support specialist in the quality department for Bischofszell Food Ltd in Obermeilen.