As a flavor ( Greek ἄρωμα aroma , German , Spice ' , fragrance', ' Perfume '), a specific smell and / or taste designated by chemical substances or mixtures of substances is caused, in products such as food , stimulants or drugs containing could be.
Many flavors can be traced back to specific individual organic compounds . These flavoring substances individually belong to chemically different organic substance classes. Often they are aromatics , esters , terpenes , alkylpyrazines , aldehydes or ketones . When examining an aroma profile, the contribution of identified aroma substances to the overall impression is each characterized by an aroma value (see aroma value concept ). If the aroma is particularly characterized by a flavoring substance, this is called the key flavoring substance .
If the aroma of a food differs from the typical aroma, it is called an off- aroma .
Industrial products are often mixed with concentrated solutions of odorous substances in order to avoid the use of natural products for reasons of cost or to achieve a product ideal with a constant aroma despite natural fluctuations. If the flavor of the product is insufficient, natural or nature-identical flavorings are used as food additives . Some flavors can be reproduced very well with aromas, for some others this is not (yet) true.
Due to meteorological and political influences, there may be strong fluctuations in the quality and quantities of natural flavors (see vanilla ). The production of flavorings is becoming increasingly important economically, which is due in particular to their use in industrially processed and packaged foods. In 2011, around 10.6 billion US dollars were sold worldwide with flavorings, both naturally obtained and synthetically produced. The prices for the respective aroma vary greatly between these subgroups.
|Structural formula of the key flavoring agent||Aroma-defining for|
Sensory and cognitive basics
Aromas are mainly perceived through the sense of smell , as volatile aromas reach the sensory cells of the olfactory mucous membrane in the nasal cavity via the pharynx-nose connection when eating . The olfactory mucous membrane in humans contains around 10 million olfactory cells , which can be differentiated according to their olfactory receptor into around 350 types of receptors, each of which is excited by a specific molecular structure of an odorous substance . By stimulating different types of receptor cells at the same time , a far higher number of different olfactory sensations is possible, and humans can learn to distinguish several thousand from them.
The sense of taste localized on the tongue , on the other hand, can only recognize five flavors (sweet, sour, salty, bitter and umami ). In addition, there is the sharpness of the taste , which is perceived via heat and pain sensors and is therefore not counted among the flavors in the narrower sense.
Creation of flavorings
In vegetables, flavorings are often only formed when the cell structures are destroyed during processing. In the process, enzymes are released, through which aromatic substances are formed from various precursor molecules. A common example is the aroma of garlic and onions, which can only be clearly heard after cutting. Because some enzymes are only found in certain types of vegetables, characteristic aromatic substances can then be created.
Most of the aromatic substances are produced in fruits when the metabolism is switched from anabolic to catabolic during the ripening phase. Then, depending on the metabolic pathway, different biomolecules are broken down, whereby aromatic substances are formed. Chopping fruits interrupts the synthesis of flavoring substances and, similar to vegetables, enzymatically controlled reactions occur. This means that existing flavorings can continue to react to form new flavorings. Therefore, the flavors of fruits and fruit juices usually differ.
The Maillard reaction is mainly responsible for the creation of flavorings when heated. Amine compounds (mostly amino acids) react with reducing compounds (mostly reducing sugars ) and, in many successive reactions, numerous aromatic substances such as B. pyrazines .
In addition, further aromatic substances can be formed by pyrolytic decomposition , especially at higher temperatures .
. The flavors Regulation (EC) No 1334/2008 divided flavors in six different categories: flavoring substances , flavoring preparations , thermal process flavorings , smoke flavorings , flavor precursors and other flavorings .
Aroma substances are chemically defined substances with aroma properties. So far, around 10,000 aromatic substances have been identified in nature. The flavor industry uses around 2,500 flavor substances. In general, flavorings can be divided into two subcategories:
- Synthetic flavors are created using synthetic processes. They are either nature-identical flavorings or artificial flavorings . The nature-identical flavorings follow a model in nature and correspond to this model in their molecular structure, e.g. B. synthetically produced vanillin. Artificial flavorings, on the other hand, have no role model in nature. In contrast to the earlier Aroma Directive 88/388, the new Aroma Ordinance no longer differentiates between nature-identical and artificial aromas. Until the European positive list came into effect on April 22, 2013, Germany only permitted 15 artificial flavorings for use in food, e.g. B. ethyl vanillin .
- Natural flavoring substances are flavoring substances that are obtained by legally stipulated physical (e.g. distillation and extraction), enzymatic or microbiological processes. Starting materials for production can be of vegetable, animal or microbiological (e.g. yeast) origin; Both the raw materials and the manufacturing process are natural. Natural flavoring substances must have been proven in nature. Natural flavors include, for example, natural vanillin.
The European Food Safety Authority (EFSA) has tested all natural and synthetic flavorings for their harmlessness. The substances that can be used are listed in a positive list (Union list) (Implementing Regulation 872/2012).
Aroma extracts are complex mixtures of natural aroma substances. For example, there are extracts from fruits, spices, herbs, meat, fish and vegetables. They are obtained just like natural flavorings and are subject to the same legal requirements.
Thermally obtained reaction flavors
Thermally obtained reaction flavors are created through controlled heating of sugar and nitrogen-containing ingredients (e.g. grape sugar with beef extract). The aroma is only created by heating, for example when baking bread or roasting meat.
Smoke aromas arise when smoke condenses in water, i. H. is caught. In order to produce smoke aromas, manufacturers have to comply with and strictly control certain legal requirements with regard to temperature, water content of the wood and air supply.
Aroma precursors (for example carbohydrates or amino acids) have no or only limited properties of their own that impart odor or taste. However, they develop this through reaction with other components during food production.
Other flavors are those flavors that do not fall under the aforementioned categories, such as grill-like flavors that are made by heating vegetable oils.
Handling of the flavors
In order to be able to use and dose flavors in food better, they are usually mixed with carrier substances or solvents, for example with starch , lactose or alcohol. For technological reasons, some flavors also contain food additives, such as emulsifiers or antioxidants. These additives may only be used if they have been checked for their safety and if they have been approved by law.
Labeling of aromas
The European Flavor Regulation regulates the labeling of flavors. This applies to the sale of flavors to the food industry or to end consumers (e.g. vanilla sugar or baking flavors) as well as to the designation of flavors in the list of ingredients in food packaging.
The term “aroma” can always be used if the food contains one or more of the six legally defined aroma categories. It is also possible to describe the aroma more precisely (orange oil) or to describe it (strawberry aroma). The addition of caffeine and quinine must always be labeled separately. This also applies to smoke aromas, provided they give the food a smoky taste.
The European Flavor Regulation places special demands on the use of the term “natural”. These apply equally to the labeling by the flavor manufacturer as well as to the designation of flavors in the list of ingredients for foods. In principle, the term “natural” may only be used if the aroma contains only aroma extracts or natural aroma substances. Synthetic aromas, thermally obtained reaction aromas, smoke aromas, aroma precursors or other aromas must therefore not be given the addition “natural”. Vegetable protein hydrolyzate, which is declared as “spice” or “broth”, is not a natural ingredient in the sense of the Flavor Ordinance.
In the interests of improved consumer protection aimed at by the legislature, the raw materials of the aroma (e.g. strawberry or vanilla) should be mentioned when using the term “natural”, unless these are not recognizable in the aroma or taste of the food. Using the example of "strawberry", the following labeling options can be distinguished:
- "Natural strawberry flavor": Such a flavor comes either exclusively from strawberries (e.g. strawberry extract) or at least 95% from strawberries. The remaining 5% are natural flavorings or flavor extracts that do not come from strawberries. These additional aromas may only have a rounding effect and not significantly change the actual taste.
- "Natural strawberry flavor with other natural flavors": With such a flavor, the proportion of strawberries is below 95%. Natural flavorings or flavor extracts that do not come from strawberries can be added to the flavor. However, the taste of the aroma components derived from strawberries must be easily recognizable.
- “Natural flavoring substances”: Such a flavoring does not contain any extracted components of the strawberry or any other flavoring extracts. The aroma was made exclusively from natural aromatic substances. A reference to the taste of the strawberry is not allowed.
- "Natural flavor": Such a flavor contains natural flavoring substances or flavoring extracts that come from various raw materials. It tastes like strawberries, but was not or only to a small extent obtained from strawberries. Reference to the taste of the strawberry is not permitted here either.
Even if an aroma meets the requirements for the use of the term “natural”, the aroma manufacturer or food manufacturer may only label the aroma in question as an “aroma” or use a more precise designation / description. A “natural strawberry flavor” or “natural strawberry flavor with other natural flavors” could therefore also be labeled as “flavor” or “strawberry flavor”. The use of the term “aroma” in the list of ingredients is not automatically to be equated with the use of synthetic aroma substances.
The addition of artificial flavors instead of natural flavors (or in addition) can be detected qualitatively and quantitatively by means of an enantioselective analysis . The enantiomeric ratio is used, the property of many natural substances that individual aromatic substances occur in a characteristic distribution of their enantiomers (these are stereoisomeric chemical compounds, see also chirality ). This analysis is primarily used to test natural fruit flavors and foods flavored with natural fruit flavors. This can be used to determine whether the products are labeled in accordance with the regulations and whether only natural flavorings are present.
One of the most comprehensive lists of organic flavors was presented by Georg Cohn as early as 1914.
The European Commission has drawn up a list that groups together all the flavoring substances used in the EU.
On October 1, 2012, the EU Commission published a list of the flavoring substances approved in the EU (Union list). This will be valid from April 22, 2013 and after the transition period of 18 months specified in the Flavor Ordinance 1334/2008 has expired, it will be binding for all flavors produced in the EU. After this transition period on October 22, 2014, only flavorings that are manufactured from the substances listed in this Union list may be placed on the market. Components of aromas from the categories “aroma extracts” (if produced from food) and “thermally obtained reaction aromas” (insofar as the stated production conditions have been complied with) do not need to have been registered in the Union list. Flavors and foods that do not comply with this ordinance may, however, still be consumed up to the expiry of the respective best-before date.
Since the taste sensors (receptors) are chiral , enantiomers usually have different tastes. Most of the D - amino acids taste sweet, while the L - amino acids are bitter or almost tasteless. The dipeptide methyl ester aspartame only tastes sweet if both amino acids involved in the molecular structure are L -configured. The terpene ( S ) -carvone smells like caraway seeds , while ( R ) -carvone smells minty . The left form of the terpene lime smells of lemon , the legal form of orange .
The odor threshold is also usually different for enantiomers and other stereoisomers. The 8 stereoisomers of wine lactone provide an impressive example . All of them have different odor thresholds that differ by a factor of 1,000,000,000.
In nature, individual enantiomers are often formed preferably with a certain enantiomeric excess , while synthetically produced flavorings are often obtained as a racemate and are not further separated for economic reasons. Therefore, in some cases the use of synthetic flavorings can be determined by an enantiomer-selective analysis (e.g. by gas chromatography with a chiral phase).
Toxins in flavors
Legal quantity restrictions have been introduced for the following compounds added to food through flavoring substances, as they can be toxic:
- Agaricic acid (until January 19, 2011, then removed)
- Aloin (until January 19, 2011, then removed)
- Berberine (until January 19, 2011, then removed)
- Prussic acid
- Estragole (added from January 20, 2011)
- Hypericin (until January 19, 2011, then removed)
- Menthofuran (added from January 20, 2011)
- Methyleugenol (added January 20, 2011)
- Santonin (until January 19, 2011, then removed)
- Teucrine A (added January 20, 2011)
These are exclusively substances that could not be removed from the aroma using appropriate processes. Most of these toxins are produced by plants , the starting material for most flavors, to protect themselves from natural enemies. So it is not a question of controlled conflicts of interest, but a real problem such as with acrylamide .
With the new EU Flavor Regulation coming into effect on January 20, 2011, the substances agaricic acid, aloin, berberine, hypericin and santonin are no longer subject to maximum quantity restrictions; instead, the substances estragole , methyl eugenol , teucrin A and menthofuran are newly included.
The new EU Flavor Regulation 1334/2008 regulates in its Annex III, Part B, which maximum quantities of these naturally contained but undesirable toxins may be contained in which foods. For all other foods there are no longer any general maximum levels. In this case, responsibility is transferred to the food manufacturer who, according to Art. 14 of the EU Basic Regulation 178/2002, must observe that food must be "safe".
A specialty of the toxins is capsaicin (hot substance of chilli pods), which as a pure substance may not be added to food in any form, but is allowed without restriction via the source of the chilli extract.
In food chemistry , key aromas that shape the characteristic aroma of individual foods are called character impact compounds, e.g. B. Vanillin as a carrier of the aroma of the spice vanilla or the raspberry ketone .
|material||Aroma character||Occurrence (example)||receipt|
|( R ) limes||Citrus||orange juice|
|Thioterpineol||Pomelo / grapefruit||Grapefruit juice|
|Benzaldehyde||Bitter almond||Almonds , cherries , plums|
|Neral / Geranial||lemon||Lemons|
|( R ) - (-) - 1-octen-3-ol||mushroom||Mushrooms , camembert|
|( E , Z ) -Nona-2,6-dienal||cucumber||Cucumbers|
|4-hydroxy-2,5-dimethyl-3 (2 H) -furanone||caramel||Cookies , dark beer , coffee|
|2-acetyl-1-pyrroline||roasted||White bread - crust|
|Isopentyl acetate (banana oil, pear ether)||Banana , pear||Bananas, pears||internal,|
|2-methylbutyric acid ethyl ester||Apple||Apples||internally|
- Thomas A. Vilgis, Thomas A. Vierich: Aroma - Die Kunst des Würzens , Stiftung Warentest , Berlin, 2nd edition (2013), ISBN 978-3-86851-911-2
- Electronic Flavors Register of the European Commission - The database currently lists 2763 flavors.
- Announcement of the new version of the Flavor Ordinance of May 2006 ( BGBl. I p. 1127 ) (PDF file; 74 kB)
- Questions and answers on food flavors (German Association of the Flavor Industry)
- Quarks & Co .: mirror-image flavorings
- Dossier Fragrances & Flavors from SimplyScience
- Additive Museum Hamburg: Natural flavorings
- Ceresana: Market study of flavorings .
- El-Zaeddi H, Martínez-Tomé J, Calín-Sánchez Á, Burló F, Carbonell-Barrachina ÁA: Volatile Composition of Essential Oils from Different Aromatic Herbs Grown in Mediterranean Regions of Spain. , Foods. 2016 May 25; 5 (2), PMID 28231136
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- Flavorings - legal basis and analysis , website of the Bavarian State Office for Health and Food Safety .
- Georg Cohn: The organic flavors. Siemenroth Verlag, Berlin 1914.
European Commission: Database .
- , accessed on October 3, 2012 .
- Henri Brunner : Right or Left - In Nature and Elsewhere. Wiley-VCH, 1999, ISBN 3-527-29974-2 , pp. 142-145.
- Hans-Dieter Belitz, Werner Grosch & Peter Schieberle: Textbook of food chemistry . 6th edition. Springer, Berlin 2008, ISBN 978-3-540-73201-3 , chap. 5 , p. 360-362 , doi : 10.1007 / 978-3-540-73202-0 .
- Hans-Dieter Belitz, Werner Grosch & Peter Schieberle: Textbook of food chemistry . 6th edition. Springer, Berlin 2018, ISBN 978-3-540-73201-3 , chap. 5 , p. 346-347 , doi : 10.1007 / 978-3-540-73202-0 .
- Entry on isopentyl acetate. In: Römpp Online . Georg Thieme Verlag, accessed on June 10, 2015.
- Entry German National Library , accessed on October 10, 2014.