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Chemistry-Research |
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Flavour History, Society of Flavour Chemists Large presentation, wait for it! |
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This is one of the best sites I have seen for aroma. Great site lots of links and information |
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List of flavour sites on Cornell University site |
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Great work by the BBC and fascinating work on flavours |
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Welcome to Boelens Aroma Chemical Information Service ChemoReception Web lots of links Taste Matters Super Tasters Testing if the sample is natural |
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The Good Scents Co. Some good links Interesting analysis using leading edge technology Tea Tree Oil Australian, Main Camp |
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Your choice for spicy applications
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Candy, coffee and Roast beef have Maillard reactions in common Fast food nation |
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Flavour Science
There is a flood of information on this is the last couple of years. Vast increase in number of books written on subject. Not all volatile substances have odours. The shape and polarity of the compounds determine their odour. There are numerous optical isomers with different odours. l-carvone is spearmint whereas d-carvone is dill or caraway. Several lactones and ionones have different odours depending on their optical rotation. It is to be expected that one optical isomer will have a different threshold to its mirror image. It is only in recent years that such compounds were separated on GLC columns. This phenomenon explains the various claims that “natural” is better, meaning that synthetically made aroma compounds are different to those in nature.
Threshold value the concentration an aroma or taste can be detected (air, water and fat)
Recognition Threshold The concentration at which you can identify an odour. (air, water and fat)
Odour unit the concentration divided by the threshold
Flavour impact value the rate of change in perception with concentration.
The flavour contribution of a aroma component in a mixture to the total profile can be calculated from the total odour units and the number contributed by that aroma chemical.
Threshold in a food is dependant upon: The threshold of the aroma in air. Concentration in the food Solubility in oil and water Its Vapour pressure Partition coefficient between the air and the food pH of the food some aroma compounds are effected by the pH, weak organic acids are protionated at low pH making them less soluble and hence more volatile.
The concentration of an odour above a food is dependant on its solubility in that food and its vapour pressure and concentration in that food.
Additive and Synergistic effects The other aroma components, concentration and thresholds needs to be determined. The synergetic effects of these and their additive effects need to be determined.
We have started to assemble a data base on odour values. If we know the flavour threshold for each component in a flavour and divide it by its threshold value we can calculate the number of odour units that component contributes to the total flavour. From this information we can produce a flavour profile. Sometime in the distant future we could supply an accurate flavour profile with each flavour! This gets very complicated as we would need to know the solubility, vapour pressure as well as the threshold value in air for each component. This information is not easily available.
Threshold values of Vanillin and Ethyl Vanillin In air the detection threshold is given as 7 X 10 -6 mg/m3 of air.
Kirk Othmer (vol 10, 1993)
pH effect examples Trimethylamine has a strong fishy smell, with lemon juice or vinegar this alkaline compound is neutralised to the organic salt. Milk sours and develops a distinctive smell. This is aided by the formation of lactic acid which reduces the pH making acids such as butyric less soluble and more volatile. The opposite effect is achieved by bicarbonate of soda when used to deodorise carpets. The carpet odours which are often short chained acids are neutralised by the action of the bicarbonate which produces non volatile salts. d-limonene is hydrated to alpha terpineol in acid drinks. Lemon-containing drinks move to a lime taste with age. |
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Flavour Materials + Structures from the Good Scents Co |
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Structures of aromas compounds amazing! |