Alchemist WebPick Awarded by the webzine of ChemWeb.com Leffingwell & Associates Odor Properties & Molecular Visualization BURNT SUGAR, CARAMEL & MAPLE NOTES & Molecular Structures  Several closely related GRAS chemical structure types are responsible for providing the "burnt sugar" type notes associated with many products (caramel, cotton candy, maple sugar, cooked fruits such as strawberry & pineapple, as well as roasted products such as chicory & coffee). Here we will examine the flavor properties (odor descriptions and intensities) and show the molecular structural similarities. As will be noted, each of these very important flavor chemicals possesses the alpha-enol function adjacent to a carbonyl. Also of interest is that the replacement of methyl groups with ethyl groups in these structurally similar compounds generally results in an amplification of odor intensity. Maltol or 3-hydroxy-2-methyl-4-pyrone...C7H8O3 ............................. is an important flavor chemical that occurs naturally in products such as Caramel, Chicory, Cocoa, Coffee, Milk, Roasted Malt, Strawberry, and Bread ... just to name a few. The odor is often described as that of "cotton candy", the spun caramelized sugar product sold at fairs. Odor Detection Threshold (in water) = 35,000 ppb Sweet, fruity, berry, caramellic odor; fruity preserve-like. Very important in commercial fruit flavors.  Ethyl Maltol or 3-hydroxy-2-ethyl-4-pyrone...C8H10O3 .............................. is the ethyl analog of Maltol, wherein the 2-methyl group is now 2-ethyl. This material is not occurring in nature. The odor is also that of "cotton candy"; in fact the odor/flavor properties are nearly identical except that Ethyl maltol is 4-5 times as intense in flavor applications and perhaps slightly more fruity. I have been unable to find a published value for its odor detection threshold, but would expect it to be in the range of 10,000 ppb. Odor Detection Threshold (in water) = NA Sweet, fruity-caramellic odor; fruity preserve taste Furaneol(R) or 2,5-Dimethyl-4-hydroxy-3(2H)furanone ..C6H8O3 .......................... also known as "Strawberry furanone" or "Pineapple furanone" was originally reported in 1965 by Willhalm, Stoll & Thomas at Firmenich & Cie in Geneva as a key flavor component of strawberry [Chemistry & Ind. [London], 1629, (1965)]. At essentially the same time, Rodin, Himel, Silverstein, Leeper & Gortner [J. Food Sci., 30, 280 (1965)] found this material to be one of the main organoleptic principles of pineapple. Today, we know that Furaneol plays an important roll in the flavor of numerous fruits (Chempedak Fruit, Guava, Litchi, Pineapple, Raspberry, Arctic Bramble, Strawberry, Tomato and others), as well as in roasted products such as coffee, corn tacos (maize), cooked beef, malt, hazelnut, roasted almonds, and popcorn. While the odor threshold has been reported by various workers at values ranging from 0.4-1700 ppb, the value of 31 ppb seems most reliable. Buttery has shown that the threshold value in water is pH dependant. Odor threshold in water: 60 ppb at pH 7, 31 ppb at pH 4.5 and 21 ppb at pH 3.0 [Buttery, Ron G.; Takeoka, Gary R.; Ling, Louisa C., J. Agric. Food Chem., 43(6), 1638-40 (1995)]. Recently, Yoshihiro Yaguchi, Atsufumi Nakahashi, Nobuaki Miura, Daisuke Sugimoto, Kenji Monde, and Makoto Emura, Stereochemical Study of Chiral Tautomeric Flavorous Furanones by Vibrational Circular Dichroism, Org. Lett., 2008, 10 (21), pp 4883–4885 and Makoto Emura, Yoshihiro Yaguchi, Atsufumi Nakahashi, Daisuke Sugimoto, Nobuaki Miura and Kenji Monde, Stereochemical Studies of Odorous 2-Substituted-3(2H)-furanones by Vibrational Circular Dichroism, J. Agric. Food Chem., 2009, 57 (21), pp 9909–9915 have shown that the "strong, sugary, jammy, sweet" character is due to the (+)-(2R)-Furaneol®. Furaneol is a trademark of Firmenich. Odor Detection Threshold (in water) = 31 ppb Fruity, caramelized pineapple-strawberry odor & taste Furaneol acetate or 2,5-Dimethyl-4-acetoxy-3(2H)furanone ..C8H10O4. .......................... is the enol acetate of Furaneol. This material was added to the FEMA (Flavor extract Manufacturers Assn.) GRAS list in 1996. The author has been unable to find a reference either to the occurrence of this in nature or an odor detection threshold. However, we find this material to possess better stability to air than furaneol and believe it to have a superior cooked strawberry note. It probably finds applications wherever furaneol can be used. Odor Detection Threshold (in water) = NA Cooked caramelic strawberry note Mesifurane or 2,5-Dimethyl-4-methoxy-3(2H)furanone ..C7H10O3. .......................... Although this material accompanies the related furaneol [2,5-dimethyl-4-hydroxy-3(2H)-furanone] (FEMA# 3174) in Pineapple, Raspberry, Strawberry and Grape (and in fact is higher in concentration in some cases, such as Arctic Bamble) - and the material has a marginally lower odor threshold. This material does not excite the flavorist as much because its flavor is much more subtle and mellow. This material is an excellent blender in Fruit flavors. Sweet, fruity "sherry" like odor; Xeres wine-like note Odor Detection Threshold (in water) = 0.3 ppb Flavor threshold = 0.4 ppb (for the racemate) Yoshihiro Yaguchi, Atsufumi Nakahashi, Nobuaki Miura, Daisuke Sugimoto, Kenji Monde, and Makoto Emura, Stereochemical Study of Chiral Tautomeric Flavorous Furanones by Vibrational Circular Dichroism, Org. Lett., 2008, 10 (21), pp 4883–4885 and Makoto Emura, Yoshihiro Yaguchi, Atsufumi Nakahashi, Daisuke Sugimoto, Nobuaki Miura and Kenji Monde, Stereochemical Studies of Odorous 2-Substituted-3(2H)-furanones by Vibrational Circular Dichroism, J. Agric. Food Chem., 2009, 57 (21), pp 9909–9915 have shown that (+)-(2R)-Mesifuran is "burnt, intensive caramel" and (-)-(2S)-Mesifuran has a "lactone, coumarin like, no caramelic odor". Cyclotene or 3-Methyl-2-cyclopenten-2-ol-l-one ..C6H8O2 .......................... resembles furaneol and maltol in that it has a 5-membered ring with its enol carbonyl structure. Occurs in Cocoa, Coffee, Fenugreek, Licorice, Malt, Roasted Almond and almost all products containing sugar that are roasted. In conjunction with fenugreek solid extract, "cyclotene" is an integral part of nearly all Maple flavors. Several authors report the flavor of this material to be somewhat similar to Licorice but, to most North Americans, its flavor is closer to the syrup obtained from a sugar maple. Odor Detection Threshold (in water) = 300 ppb Very strong, caramellic-maple, lovage odor and taste 3-Ethyl-2-hydroxy-2-cyclopenten-1-one or Ethyl cyclotene ..C7H10O2 .......................... is the ethyl homolog of cyclotene and possesses a similar odor and taste. Occurs in Coffee, Tobacco & Tobacco smoke. Fenaroli (1975) indicates the flavor threshold value for this material is "5 ppm" and that it also acts as a flavor enhancer. On a relative basis to cyclotene, we expect that a more accurate threshold value is about 150 ppb (however, this is speculative, at this point). Odor Detection Threshold (in water) = 5000 ppb Very strong, caramellic-maple odor and taste 3,5-Dimethyl-2-hydroxy-2-cyclopenten-1-one or Coronol(R) ..C7H10O2 .......................... is 3,5-dimethyl analog of cyclotene and possesses a similar odor and taste. Occurs in Coffee & Tobacco smoke. Similar strong maple-caramel notes. Coronol is a trademark of Givaudan-Roure. Odor Detection Threshold (in water) = 1000 ppb Strong, maple-caramel, nutty odor/taste; similar to cyclotene 3,4-Dimethyl-2-hydroxy-2-cyclopenten-1-one or Methyl Corylone(R) ..C7H10O2 .......................... is the 3,4-dimethyl analog of cyclotene and possesses a similar odor and taste. Occurs in Coffee, Tobacco Smoke & Wood Smoke. Similar strong maple, burnt-sugar, caramel odor/taste. This material is the most potent of the cyclotene analogs. Methyl Corylone is a trademark of Givaudan-Roure. Odor Detection Threshold (in water) = 17-20 ppb Strong, maple-caramel, nutty odor/taste; similar to cyclotene 3-Ethyl-2-hydroxy-4-methylcyclopent-2-en-1-one ..C8H12O2 .......................... is the ethyl homolog of 3,4-Dimethyl-2-hydroxy-2-cyclopenten-1-one and has a somewhat more burnt, caramellic, maple-like odor. To the authors knowledge this material has only been reported in Tobacco smoke. Similar strong maple-caramel notes. Odor Detection Threshold (in water) = NA Strong, burnt, caramellic, maple-like odor 3-Ethyl-2-hydroxy-5-methylcyclopent-2-en-1-one ..C8H12O2 .......................... is the ethyl homolog of 3,5-Dimethyl-2-hydroxy-2-cyclopenten-1-one and has a more burnt, caramellic, maple-like odor. To the authors knowledge this material has only been reported in Tobacco & Tobacco smoke. Similar Burnt, caramellic, maple odor as the 3-ethyl-4-methyl isomer. Odor Detection Threshold (in water) = NA Strong, burnt, caramellic, maple odor Sotolon or 4,5-Dimethyl-3-hydroxy-2(5H)-furanone..C6H8O3 .......................... Sotolon is the key organoleptic principal of roasted Fenugreek seed. Also found in Roasted Virginia Tobacco, Sake, Sugar, Botrytized grape wine and Rice wine. Until the materials shown on this page became available, Fenugreek and Fenugreek extracts were the only good flavor concentrate source for caramel-maple notes. A product known for many years under the trade name of "Mapeline" was used by housewives and industry whenever this type of flavor was needed. Perfumers valued the powerful Fenugreek absolute for such notes. The taste and aroma of brown sugar is mainly due to sotolon (which is the main flavor principal in sugar molasses). However, Sotolon is now available commercially and is one of two extremely powerful aroma chemicals for imparting caramel-maple notes. Sotolon with a detection threshold of 0.001 ppb is nearly 30,000 time more powerful than cyclotene. The chemical which follows is even more powerful. Sotolon is also known as caramel furanone, sugar lactone and fenugreek lactone - it has the typical aroma of fenugreek or curry at high concentrations and caramel, maple syrup and burnt sugar at lower concentrations. (+)-(S)-Sotolone is "curry, walnut (strongly caramelic)" while (-)-(R)-Sotolone is "walnut, rancid". Although the aromatic nuances of both enantiomers were quite similar, the perception threshold of (S)-sotolon in dilute alcohol solution (12% vol) was >100 times lower than that of (R)-sotolon. See Pons, A.; Lavigne, V.; Landais, Y.; Darriet, P.; Dubourdieu, D., Distribution and Organoleptic Impact of Sotolon Enantiomers in Dry White Wines, J. Agric. Food Chem.; (Article); 2008; 56(5); 1606-1610; Guichard, E.; Fournier, N. Enantiomeric ratios of sotolon in different media and sensory differentiation of the pure enantiomers, In European Food Chemistry VI; Hambourg, 1991. Odor Detection Threshold (in water) = 0.001 ppb The odor thresholds in 12% EtOH/Water V/V for the enantiomers are: (+)-(S)-Sotolone - Odor threshold = 0.8 ppb (-)-(R)-Sotolone - Odor threshold = 89 ppb Maple furanone or 5-Ethyl-3-hydroxy-4-methyl-2(5H)-furanone..C7H10O3 .......................... is truly one of the most outstanding of modern flavor materials. This material is much more powerful and lasting than Methyl or Ethylcyclopentenolone and possesses more of a maple note than Sotolon. Maple furanone is a key organoleptic note in Soy sauce (hydrolyzed vegetable protein). With a detection threshold of 0.00001 ppb maple furanone is nearly 3,000,000 times more powerful than cyclotene and in fact is one of the most powerful flavor chemicals known to man. Odor Detection Threshold (in water) = 0.00001 ppb Powerful maple-caramel aroma and taste Data abstracted from Flavor-Base Copyright John C. Leffingwell 1999-2010 Leffingwell & Associates In the news Home Copyright © Leffingwell & Associates TERMS OF SERVICE.............PRIVACY POLICY