| Ester Odor isoamyl acetate banana
ethyl acetate fingernail polish remover
methyl salicylate wintergreen
ethyl butyrate pineapple
benzyl butyrate cherry
ethyl propionate rum
ethyl benzoate fruity
benzyl acetate peach
methyl butyrate apple
octyl acetate orange
n-propyl acetate pear
ethyl phenylacetate honey I don't know how the aroma is affected by a systematic change such as lengthening the carbon chain of the carboxylic acid or alcohol. One example in the list where the length of the alcohol chain is increased by one carbon is in methyl and ethyl butyrate. The odor changes from apple to pineapple. Doing some keyword searching, propyl butyrate is a "colourless liquid with a pineapple, apricot odour," butyl butyrate is a "colourless liquid with a fruity, pineapple-like odour on dilution," and skipping a carbon, hexyl butyrate is a "colourless to pale yellow liquid with a fruity, apricot odour." So there seems to be some similarities to the odors of the esters in this series. The odors of the acetates in the table, on the other hand, such as ethyl, propyl, and octyl acetate, differ much more from each other. I found the other descriptions at the Food and Agricultural Organization of the United Nations website at http://www.fao.org/ag/agn/jecfa-flav/search.html.
The introduction to the experiment where the above list was provided goes on to say, "Food and beverage manufacturers are thoroughly familiar with these esters and often use them as additives to spruce up the flavor or odor of a dessert or beverage. Many times odors do not have a natural basis, as is the case with the “juicy fruit�?principle, isopentenyl acetate. An instant pudding that has the flavor of rum may never have seen its alcoholic namesake—this flavor can be duplicated by the proper admixture, along with other minor components, of ethyl formate and isobutyl propionate. The natural flavor and odor are not exactly duplicated, but most people can be fooled. Often only a trained person with a high degree of gustatory perception, a professional taster, can tell the difference. A single compound is rarely used in good-quality imitation flavoring agents. A formula for imitation pineapple flavor that might fool an expert includes 10 esters and carboxylic acids that can easily be synthesized in the laboratory, and 7 essential oils that are isolated from natural sources. Flavor is a combination of taste, sensation and odor transmitted by receptors in the mouth (taste buds) and nose (olfactory receptors). There are four different tastes (sweet, sour, salty, and bitter). The perception of flavor, however, is not so simple. The human actually possesses 9000 taste buds and odor plays a big role in the perception of taste. Although the “fruity�?tastes and odor of esters are pleasant, they are seldom used in perfumes or scents that are applied to the body. The reason for this is that the ester group is not as stable to perspiration as the ingredients of the more expensive essential oils. The later are usually hydrocarbons (terpenes), ketones and ethers extracted from natural sources. Esters are only used for the cheapest toilet waters, since on contact with sweat, they hydrolyze, giving organic acids. These acids, unlike their precursor esters, generally do not have a pleasant odor.
O O
|| ||
R-C-OR�?nbsp; + H2O ––�?gt; R-C-OH + R’OH
Butyric acid, for instance, has a strong odor like that of rancid butter (of which it is an ingredient) and is a component of what we normally call body odor. Ethyl butyrate and methyl butyrate, however, are esters that smell like pineapple and apple, respectively." An interesting subject! We also have a member here, Norman, who is a flavorist by profession, and knows infinitely more about this topic. Maybe he will catch your message and add some comments. Steve |
Free Forum Hosting
Important Announcement
First 