Technologies for the Recovery of Aromas (Cerutti, 2006)
- 1) Ultra-filtration (UF) for the production of citrus aromas. UF can be used in the same way as reverse osmosis for the separation of limonene and other terpene compounds.
- 2) Extraction with supercritical carbon dioxide, the same technology used to recover cholesterol from fats of animal origin, for example from butter. A supercritical fluid, such as CO2, has a number of valuable features for the flavoring industry. The supercritical CO2, thanks to its high selectivity, can be used in rectifying column in the deterpenation of essential oils. Interesting applications concern the aromatic extraction from flowers and leaves, on the basis of results already achieved in a number of plant such as absinth, angelica, cumin and thyme, mint and aromatic calamus, celery and rosemary, red pepper and vanilla, juniper, and coffee. Such an extract shows characters of higher aromatic purity.
- 3) Biotechnology, thanks to the more and more extensive knowledge of microorganisms and enzymes, their characteristics, functions, and potentiality new horizons are opening up for production processes of complex flavoring preparations and also of single molecules classified as natural.
The extraction process of natural aromas from vegetable and / or animal products is expensive, considering the relatively low concentration of the aroma in the raw material. Mostly, the extract must be subsequently refined to remove unwanted molecules and impurities. Furthermore, the raw materials control is difficult as their quality depends on several factors like season, variety, degree of ripeness, climate, plant diseases, and pesticide contamination.
In order to overcome these difficulties, through the development of chemical knowledge and development of new technologies, the chemical synthesis is applied for the following:
- • Natural-identical molecules: Once identified the structure of the desired aroma, the chemical synthesis in the laboratory can be made. Natural-identical molecules are generally permitted in food and beverages, at optimal doses in accordance with GMP. Nowadays are in use (Cerutti, 2006) ethyl acetoacetate, methyl acetoacetate, p-tolual- dehyde, allyl caproate (allyl hexanoate), rescorcinol dimethyl, methyl-cyclopentelon- one and delta-undecalactone (IUPAC: 6-Hexyltetrahydro-2H-pyran-2-one).
- • Molecules not chemically identical to an substance naturally present in a raw material of animal or vegetable origin. Based on the toxicological knowledge available to date, some flavoring compounds not detected in the original foodstuffs are allowed. We can mention
- • Allyl cyclohexylpropionate, ethyl methyl phenyl glycidate, ethyl vanillin (IUPAC: 3-etossi-4-idrossi benzaldeide), oxycitronellal, methyl ionone, naphthyl methyl ketone and propenyl guaethol (Cerutti, 2006). These products are produced by chemical synthesis and must meet purity requirements established by law. The main fields of application are candy, ice cream, candies, and puddings. Ethyl vanillin and propenyl guaethol are also used in certain creams and jams and biscuits.
In the food industry the use offlavor enhancers (flavor improvers) is widespread. That is, they are flavoring substances without any aromatic note. The compounds of greatest interest are: 
These are molecules that at the correct dose of use do not present any risks to the consumer's health. To facilitate the homogeneous dispersion of the aroma in food products, some dispersion agents may be used, such as (Cerutti, 2006):
- • Alginic acid and derivatives, agar agar and locust bean flour, pectin and carrageenan, gum arabic and tragacanth gum, and animal gelatines
- • Magnesium carbonate, sorbitol and glycerol, glycerol di- and tri-citrate, triethyl citrate, and 1,2-propylene glycol
- • Sorbic acid and its salts, sulfites and bisulfites sodium, ascorbic acid, BHA, and gallates
- • Mono- and diglycerides of fatty acids, sucrose esters, or sucrose esters
- • Citrate and sodium chloride, sugars, and starch
The new frontier of research for flavorists is the so-called flavor modifiers, molecules able to remove unwanted off notes and/or modify perceivable taste or impact of food and beverages without modifying the real flavor. They are developed and produced in a variety of forms to meet the needs of food developers, because they are ideal for low- calorie, fortified, sugar-free, low-fat, and botanically enhanced foods and beverages. Flavor modifiers may be:
- • Salt replacers (reduce salt perception, minimize metallic taste, enhance savory flavors)
- • Sugar replacers (enhance sweet perception, help to reduce calories)
- • Fat replacers (create creamy perception for low-fat products)
- • Masking flavors (reduce sour perception without affecting pH; reduce bitter aftertaste; minimize astringent perception; reduce metallic/chalky aftertaste; mask off notes; prevent “fishy” taste; reduce green grassy/grainy hay-like notes)
Since flavor is one of the most important characteristics of food, the ultimate goal of encapsulation is to control aroma release and to improve stability during processing and consumption of the final product. In general, aroma releases from food before and after eating, depends on its features and physical state of the matrix. Thanks to encapsulation, a food compound such as aroma is covered with a protective wall material and it is protected against evaporation, chemical reactions (such as flavor-flavor interactions, light-induced reactions, oxidation), or migration in a food (Madene et al., 2006). Flavors are often encapsulated to improve stability, thereby extending shelf-life, and this is most commonly achieved by spray drying with gum arabic. Konjac glucomannan, maltodextrin, and starch octenyl succinate as well as binary blends could be used as covering agents. Liposomes can be used to incorporate many fat-soluble flavors into the lipid bilayer. Flavors such as vanilla, citral, and menthol are lipid soluble.
Spray-chilling is a convenient technology to produce lipid particles with aroma (Longo et al., 2006).
-  Glutamic acid (E 620) and its salts monosodium glutamate (E 621, known as MSG),monopotassium glutamate (E 622), calcium diglutamate (E 623), monoammoniumglutamate (E 624), and magnesium diglutamate (E 625) • Guanylic acid (E 626) and its derivates, known as disodium guanylate (E 627),dipotassium guanylate (E 628), and calcium guanylate (E 629) • Inosinic acid (E 630) and its derivates disodium inosinate (E 631), dipotassiuminosinate (E 632) and calcium inosinate (E633)