Posts Tagged ‘coffee’

TGIF: Hot coffee with industrial laser

Friday, May 11th, 2007

Such an advanced setup, and then he uses instant coffee???!!!!

Found via everydayscientist a while ago…

Two flavour pairing case studies

Saturday, May 5th, 2007

In previous posts and comments I have suggested that flavour pairings based on key odorants could be explored by looking at odor activity values (= ratio of volatile compound to it’s threshold). If two foods share one or more key odorants, chances are that they will go well together. It is also reasonable to assume that the more key odorants are shared, the more similar the flavours will be and the more likely it is that the foods will blend well and match each other.

Having initiated the TGRWT event I figured I should try to see if there was any OAV data available for coffee, chocolate and garlic. I was lucky to find OAVs for coffee (both arabica and robusta beans) and cocoa. To compare coffee and cocoa I sorted the flavour compounds in a descending order based on the OAV, keeping only the 20 first compounds. I turned out that 7 out of 20 key odorants in coffee and cocoa are shared, corresponding to 28/25% and 39% respectively of the total “odor activity” (= sum of OAV of top 20 odorants). Here’s the whole list:

(I hope the authors stuck to the IUPAC naming conventions as I did not take the time to check if synonyms were present in the compounds lists)

To compare this with a random pairing I search for more OAVs and found data for parmigiano reggiano and mango, so I repeated the excercise. Among the 20 odorants with the highest OAVs respectively for coffee and mango there was no overlap. A neglibile overlap was found between cocoa and mango: one odorant (linalool) was present in both with OAVs corresponding to 0.03% and 0.05% of the “odor activity” respectively. The fact that there is no overlap between coffee or cocoa and mango does not imply that they don’t go well together, only that their key odorants don’t match. Parmigiano reggiano and cocoa however had a lot in common, as seen from the table below. In fact 6 out of 20 key odorants, representing 36% and 89% of the “odor activity” for parmigiano reggiano and cocoa respectively.


The degree of overlap between parmesan and cocoa is in fact better than for coffee and chocolate when judging by the percentages (albeit with one less odorant), so this pairing will certainly be included in a future TGRWT event! A quick google search revealed that chef Masaharu Morimoto has come up with a recipe combining cocoa and parmesan:

Chocolate Carbonara with Parmigiano Reggiano Cream

Chocolate Pasta:
1 pound all-purpose flour
4 eggs
½ cup cocoa powder
1 Tablespoon olive oil

Pasta Sauce:
2 cups cream
4 egg yolks
½ cup sugar
½ cup Parmigiano Reggiano

For the Chocolate Pasta:
Sift flour and cocoa powder together and knead in the eggs and olive oil for 15 minutes. Rest for another fifteen minutes then roll and cut in a pasta machine. Heat up a pot of lightly salted water and boil pasta until al dente.

For the Pasta Sauce:
In a medium sauce pot scald the cream. In a separate bowl, whisk together egg yolks, Parmigiano Reggiano, and sugar. Temper this mixture into the hot cream and bring to a light simmer, whisking constantly to prevent curdling.

Unfortunately I couldn’t find any OAVs for garlic, so I haven’t been able to verify the triple pairing forming the basis for TGRWT #1. The claim was that coffee has dimethyl sulfide in common with garlic, and methyl pyrazine in common with chocolate. The table above confirms that coffee and chocolate have several methyl pyrazines in common, but dimethylsulfide is not among the 20 key odorants in coffee. This puzzles me, but there could of course be other volatile compounds that garlic shares with coffee. There should also be quite a difference between raw garlic (not to mention between whole, crushed and possibly even minced) and roasted garlic. If I overlooked something (or perhaps a paper with OAVs for garlic), please drop me an email about this. The OAVs of garlic could easily be calculated if data on volatile compounds in garlic and threshold concentrations are available.

I did a search on coffee, cocoa and garlic on The Good Scents Company website as described previously and found the following compounds either naturally occuring or used for recreating the aroma of coffee, cocoa and garlic:

  • 5-methyl furfural (found naturally in all three, used for coffee and garlic)
  • benzothiazole (found naturally in cocoa, used in all three)
  • 2-furfuryl mercaptan (found naturally in coffee, used in coffee, garlic cocoa)
  • isovaleraldehyde (found naturally in coffee and cocoa, used in all three)
  • ethyl methyl sulfide (found naturally in coffee and cocoa, used in coffee and garlic)
  • bis(2-methyl-3-furyl) disulfide (used in all three)
  • butyraldehyde (found naturally in all three)
  • S-(methyl thio) butyrate (used in all three)
  • isopropyl mercaptan (found naturally in garlic, used in coffee and cocoa)
  • So there are obviously similarities similarities between coffee, chocolate and garlic, but the question is whether these compounds are key odorants or not.

    It’s only fair enough to add that the concept of odor activity values has it’s limitations. Some are related to matrix effects, because thresholds are not necessarily recorded in a matrix mimicking the food product. Possible synergies between flavour compounds are disregarded (examples are known where sub-threshold concentrations are detected in the presence of other volatile compounds). Also, the underlying assumption that the odor intensity increases linearily is not quite correct. The typical intensity vs. concentration curve is more ‘S’ shaped with an expansive, linear and compressive region as shown below. At low concentrations (expansive region) synergism (also known as hyperadditivity or mutual enhancement) is observed. At high concentrations (compressive region) antagonism (or subadditivity or mutual suppresion) is observed. This means that a high OAV overestimates and a low OAV underestimates the impact of the individual compounds. This also means that the odor activity percentages calculated for the pairings above should be take with a pinch of salt. In between these extremes normal additivities are observed.


    Even though OAVs are not phsychophysical measures of the perceived odor intensity, they compare quite well with models that take different aspects of sensing into accout. The validity of the found OAV can also be tested by a recombination of the flavour compounds to see how good it imitates the original product studied. I can recommend the freely downloadable article “Evaluation of the Key Odorants of Foods by Dilution Experiments, Aroma Models and Omission” (DOI: 10.1093/chemse/26.5.533) for those interested in reading more about the science.

    Despite the drawbacks and limitations I think OAVs can and will be helpful when studying the flavour pairing hypothesis.

    Tips: You can read more about OAVs in books which are (partly) available through Google books.

    TGRWT #1 roundup – coffee, chocolate, garlic

    Wednesday, May 2nd, 2007

    It’s time to sum up the contributions to the food blogging event They go really well together (TGRWT). There were five seven contributions plus a number of suggestions in the comments to the announcement post and I would like to thank you all very much indeed for taking time to experiment in your kitchens! Here are the results (in no particular order):

    tgrwt-1-roundup-lamiacucina.jpg Lamiacucina: Candied, chocolate coated Garlic. Garlic cloves were heated in a strong sugar-coffee solution. Cloves were then dried and coated with chocolate. Succession of taste and aroma: strong, unpleasant character of garlic. Bloggers verdict: disappointing!

    tgrwt-1-roundup-matthieu.jpg Blog & White: Chocolate-Coffee Mayonnaise with Garlic. Adapted from Hervé This’ chocolate mayonnaise with added coffee and garlic. Succession of taste and aroma: chocolate aroma is followed by taste of garlic and sweetness of chocolate, coffee aftertaste. Bloggers verdict: Interesting (but wife hates it!).

    tgrwt-1-roundup-tara.jpgShould you eat that: Mocha Tofu Mousse with Garlic. Roasted garlic cloves were added to an adapted version of Scharfenberger’s mocha tofu mousse. Succession of taste and aroma: coffee followed by chocolate, then a subtle, sweet, roasted garlic aftertaste. Bloggers verdict: I would definately make it again!

    tgrwt-1-roundup-msblog.jpg M’s blog: Mocca garlic creme brulee. As the name suggests a creme brulee with espresso, chocolate and a garlic clove. Bloggers verdict: Tasted like mocca creme brulee.

    tgrwt-1-roundup-khymos.jpg Khymos: Coffee espuma with garlic and chocolate. Coffee and cream espuma with added chocolate and roasted garlic. Succession of taste and aroma: coffee with sweet taste, then a faint chocolate aroma followed by a garlicky aftertaste. My verdict: Aromas blend well together. Would use less garlic for dessert version.

    Entries added after first posting:

    tgrwt-1-roundup-grape.jpgGrapeThinking: Roasted garlic dipped in melted chocolate with coffee beans. Succession of taste and aroma: Roast garlic doesn’t have much of a smell. Chocolate and coffee always smell good. Bloggers verdict: Good aroma. Taste was good in the beginning; slightly funky aftertaste. Texture of garlic was good.

    tgrwt-1-roundup-kompottsurfer.jpg Kompottsurfer: Espresso-risotto with bitter chocolate, tomatoe and mozzarella (posting in German). Bloggers verdict: Color was a disaster, and difficult to get relative proportions right. But aroma worked out prette nice.

    From the different comments it seems that garlic is a difficult beast to tame, especially when used raw. A major challenge is finding the right balance between the aromas. Garlic was either too strong or almost absent. Chocolate and coffee however seem to go very well together (and my preliminary search for odor activity values confirm this – more on this soon!).

    I also find it interesting that ratios of chocolate, coffee and garlic used influence the succession of aroma and taste (“>” meaning “followed by”):

  • coffee > chocolate > garlic (mousse and espuma)
  • chocolate > garlic > coffee (mayonnaise)
  • garlic > chocolate, coffee (chocolate coated garlic)
  • Is it a coincidence that coffee is the first aroma noticed in the two “foamy” preparations or is this simply a result of the different ratios used?

    I should mention that I also tried to make a chicken mole using the three ingredients. Based on a couple of recipes from the net and some tinkering I ended up with a chicken mole that had a little too much chocolate… It tasted … eh … strange, so I decided to add balsamic vinegar which helped a lot! The coffee blended in very well however, so this is how I would make it the next time using less chocolate:

    Chocolate coffee chicken mole
    800 g canned, crushed tomatoes
    750 g chicken breast,
    1 red chili, chopped
    2 t chili paste
    2 onions, chopped
    6 cloves of garlic, chopped
    3 dL coffee
    150 g pistacchio nuts, chopped
    1 t ground cumin
    30-50 g dark chocolate
    2 T sugar
    1-2 T balsamico vinegar

    Brown onions. Add the rest and simmer. Season to taste with chocolate, balsamico vinegar and sugar. Serve with rice. Sprinkle with coriander/cilantro or ruccola/rocket salad.

    There were also a number of recipe suggestions in the comments to the three posts on the coffee/chocolate/garlic theme.

    Coffee espuma with garlic and chocolate (TGRWT #1)

    Sunday, April 22nd, 2007


    For the food blogging event They Go Really Well Together (TGRWT #1) I decided to used baked garlic. Baking gives garlic a slightly sweet, mellow taste and I figured this might work well with the soft texture of an espuma. Just make sure you get fresh garlic without green sprouts – they will give a bitter taste.

    4 cloves of baked garlic (baked whole, 30 min @ 150 °C)
    3.5 dL strong coffee
    30 g sugar
    40 g chocolate (70% cocoa)
    ground cardamom
    3.4 g gelatin (= 2 sheets)
    1.5 dL heavy cream (38% fat)
    1 iSi cream charger

    Mix garlic cloves and coffee with blender or hand-held mixer. Add chocolate, a pinch of cardamom and heat while dissolving sugar. Stir in pre-soaked gelatin. Cool, add heavy cream, sift through fine mesh to remove remaining pieces of garlic and fill 0.5 L iSi gourmet whipper. Charge with 1 cream charger and leave in fridge over night. Serve with a drizzle of instant coffee.

    How it tastes? In the finished espuma served cold, the first aroma noticed is coffee accompanied by a sweet taste on the tongue. This is followed by a faint chocolate aroma which then gives way for an aftertaste dominated by garlic. It’s quite surprising and the aromas blend well together. I used 30 g of chocolate, but I’ve increased it to 40 g in the recipe since the cocolate aroma was a little weak. As for uses, I think it would go well with a steak for instance. If used as a dessert I would perhaps reduce the amount of garlic to 2 or 3 cloves so as not to overwhelm the guests (unless they frequent the restaurant Garlic & shots in Soho, London where even the beer is served with garlic!).


    TGRWT #1: Garlic, coffe and chocolate

    Tuesday, April 17th, 2007

    Reading the comments on how to prepare a dish using garlic, coffee and chocolate, I figured it could actually be a good idea to make this into a food blogging event. Inspired by Is My Blog Burning (IMBB), Sugar High Friday (SHF) and the like, I hereby launch a new food blogging event called They Go Really Well Together (TGRWT).

    The name refers to flavour pairing of ingredients based on their content of volatile aroma compounds. The idea behind flavour pairing is that if two (or more) foods have one or more volatile compounds in common, chances are good that they might taste well together. Click for a list of other flavour pairings and to read previous blog posts on the topic. The molecule shown in the logo is of 2-methylfuran-3-thiol, a very potent aroma chemical found in coffee, chicken, meat, fish and popcorn – to mention a few.


    Many flavour pairings seem strange at first, especially when the combination is not found in any recipes. To illustrate the flavour pairing one can always just eat the two ingredients together. But it would be so much nicer to actually make a proper dish out of it. Therefore I’m quite excited to see what the creative minds of all the food loving bloggers can come up with!

    This is how the first round of the blogging event works (hereafter referred to as TGRWT #1):

    1. Prepare a dish that combines garlic, coffee and chocolate. You can either use an existing recipe (if there is any) or come up with your own.
    2. Write a entry in your blog by May 1st with TGRWT #1 in the subject and make sure to include a link to the header of this post for trackback links. Readers will probably be particularily interested in how the flavour pairing worked out, so make an attempt at describing it.
    3. Deadline for submissions is May 1st. A round-up will be posted by me here some days later with pictures.
    4. Please send me an email at webmaster (at) khymos (dot) org with the following details: Your name, URL of blog and URL of the TGRWT #1 post and a picture for your entry in the round-up.
    5. If you don’t have a blog, email me your recipe, name and location and I’ll be glad to include it in the final round-up.
    6. In due time I will ask one of the participants to host the next round on their blog (and provide an updated logo).

    Triple flavour pairing: garlic, coffee and chocolate

    Monday, April 16th, 2007

    Preparing for a presentation on flavour pairing, Bernard Lahousse at Food for design visited Franí§ois Benzi at Firmenich, a large supplier of aroma chemicals and perfume ingredients. Bernard plans to launch a website dedicated to flavour pairing soon, and in the mean time he posts about it on his blog, including this interesting expansion of the flavour pairing concept:

    …you can also use foodpairing to pair food that doesn’t match. Like chocolate and garlic. The trick then is to search for a third food product that has something in common with chocolate and with garlic. An example is coffee. Coffee has flavour components in common with garlic: Dimethyl disulfide and with chocolate: Methyl pyrazine.


    My challenge to you all is to come up with recipes that include garlic, chocolate and coffee. Any suggestions?

    Coffee cream foam

    Tuesday, April 10th, 2007


    Based on some googling of espuma and foam recipes (including Ferran Adria’s coffee espuma), I figured that the following should work:

    2 dL coffee
    2 sheets of gelatine
    3 dL heavy cream
    sugar/vanilla sugar

    Soak gelatine in cold water. Strain. Dissolve gelatin sheets in the hot coffee and stir in sugar while heating. Cool. Add heavy cream. Filter through a fine meshed sift (just in case there should be any undissolved sugar, gelatin or particles) into a 0.5 L iSi gourmet whipper. Screw on top and charge with a cream charger. Shake 2-3 times and leave in fridge for a couple of hours. Hold whipper upside down, shake once to displace mixture towards the nozzle in case it is stuck and dispense. Texture is soft and silky. Tastes delicious!

    Some more chemistry: The cream chargers contain dinitrogen oxide (N2O) which is less polar than carbon dioxide (CO2), and hence more soluble in fat (such as heavy cream for instance). Another reason why carbon dioxide is not used in this recipe is probably that when it dissolves, some carbonic acid is formed which could curdle milk based products if pH drops to much and also influence taste (but carbonated milk has actually been marketed!). The idea of using dinitrogen oxide for soda/beer has also been explored.

    Suppression of bitterness

    Sunday, October 1st, 2006

    I received an email last week from a supertaster (read more: BBC, Wikipedia) with an interesting question: Certain foods contain bitter substances that only a fraction of the population can taste. Examples include a group of compounds called cucurbitacins, found in melon and cucumbers, and propylthiouracil in broccoli. The question was whether these compounds could be neutralized by any means.

    A very simple chemical that neutralized/modifies bitter taste is salt – and the best thing is that you don’t have to be a supertaster to test this. For a simple experiment, take tonic water, taste it and then stir in some salt (start with 1/2 teaspoon). Taste it again – if you can still taste the quinine, add a little more salt. At one point the bitter taste has almost disappeared! This principle might work for cucumbers and melons as well, but of cource there could be totally different taste mechanisms responsible for the bittertaste in the two cases.

    tonic water

    It might sound strange to add salt, but in Asia, it is not uncommon to eat different fruits with salt. I am aware of unripe mangoes, guavas and honey dew melon are eaten with salt, a salty spice and soy sauce respectively. Also – some people add a small amount of salt to the water when brewing coffee – this reduces bitterness and rounds of the taste. One last example is how salty food can make a young red wine with plenty of tannins more pleasent to drink. Tannins (polyphenolic compounds) can be both astringent and bitter, depending on their molecular weight (low molecular weight tannins are predominantely bitter whereas larger molecules are more astringent).

    BTW, this has also been treated scientifically. See for instance: Breslin, P. A. S; G.K. Beauchamp, “Suppression of Bitterness by Sodium: Variation Among Bitter Taste Stimuli” Chemical Senses 1995, 20, 609-623 (link).