Author Topic: fermentation  (Read 9581 times)

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Offline November

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Re: fermentation
« Reply #20 on: February 12, 2007, 01:56:21 PM »
November, do you have any insights on the optimal rise temperature (for flavor) for the Ischia and/or Camaldoli starters using Caputo 00 Pizzeria?

I don't have anything specific to report about optimal temperatures for starters.  I've always handled my starters (when I use them, which is very rare) the same way as my dough with regard to temperature.  With the finer granularity of 00 flour, less work is needed by the enzymes to convert the starch to simple sugars, so you can get away with lower temperatures using 00 flour relative to other flours.  I've spent a lot more time with preferments than what are generally referred to as starters, as I'm only performing the extra work for better flavor.  I don't like to catch wild yeast, or keep the same dough around for the purpose of starting subsequent batches.

One way I recently tried to improve flavor is by attempting to increase lactic acid production.  I did this by incubating my starter through several washings at 33C.  According to the temperature graphs in Ganzle, et. al. this should shift the population in favor of L. Sanfranciscensis over C. Milleri.  Indeed the resultant culture smelled non-yeasty and dull-sour.

With respect to one bacteria over another, that's fine.  However, with respect to bacteria over yeast, depending on how much yeast you have in your starter, that's not usually the case.  As has been mentioned several times before, bacteria can thrive at temperatures below the comfort zone for yeast, so keeping the dough cool (as in 5 C) accomplishes your goal in the long run.  That's why food can still spoil even if kept in the refrigerator.  You may want to keep your yeast away from your starter when you have the starter at 33 C, or use extremely miniscule amounts.  The more acetic acid that is produced by the yeast, the less your bacteria will be able to function.

Unfortunately dough made with the culture, rising at 25C, showed no improvement in taste and actually lacked flavor.  I wonder if the interdependencies between the two organisms, such as the malic acid link you mention, kept the LAB from doing anything in excess of the proportion of yeast and thus defeated my skewing of the population.

Lactic acid contributes, by most people's standards, a better flavor, but acetic acid is by far a stronger acid in terms of palate sensitivity.  It's like the salt of acids.  A little bit goes a long way to enhance flavor.  By lowering your temperature to 25 C, you created conditions where comparatively speaking, less acetic acid is produced.  At the same time, less malic acid would be produced also, but keep in mind that yeast produces very little malic acid compared to acetic acid.  Since each person has their own subjective flavor preference, you apparently found a region near 30 C, with whatever amount of yeast you used, that produces the mix of acids (and related organic compounds) that are favorable to you.

I am also vexed by conflicting information in regards to the favorability of lactic vs. acetic acid for improved flavor.  Some information says lactic acid is preferable in that its non-volatility means it doesn't evaporate at baking; plus the lactic taste is more appealing than the acetic vinegary taste.  Other information points out the tongue is not where the complex tastes are registered; it's actually the nose, and thus the volatile compounds like acetic acid are preferable over lactic acid.  What are your thoughts?

First of all, lactic acid and acetic acid are both carboxylic acids with similar boiling points, so the evaporation at baking will also be similar, with acetic having only a slightly higher evaporation rate.  Due to acetic acid's smaller molecular weight, it is more penetrating and aromatic than lactic.  That's one of the reasons why our sensitivity is higher with acetic.  It's been well studied and documented that flavor is approximately half odor and half taste.  There are a lot of biochemical registers that are set off as a result of smelling your food.  It has long been believed that people ingest more when their food is cold, because the lower temperature prevents certain aromatic compounds from evaporating from the food, and triggering a response in the brain telling it how much food they've even.  Refrigeration was an invention of man, so our bodies aren't designed to deal with the consumption of food at temperatures less than around 20 C.  The effect is minimal for some people, but it's there at some level for everybody.  That's why a lot of people report being able to eat a whole box of cereal (with cold milk) before getting full.  There are few aromatic compounds in cereal to begin with, and eating it with cold milk exaggerates the effect.  So, I said that to say this, acetic acid does register with the senses (gustation and olfaction) more than lactic acid, but more so with gustation (taste).

I get around the whole idea of trying to get bacteria to produce lactic acid for me by using food products like soy butter, or my favorite so far, "Better Than Cream Cheese" by Tofutti.  The lactic acid they add to soy products like this is produced by bacteria simply fed cane sugar.  Since these products lack lactose or other milk solids, they don't taste exactly like dairy, but instead have a generic cheesy/buttery flavor which compliments pizza dough very well.  It's essentially what you're looking for but without all the work.  The primary fat is soybean oil, so I usually use about 20-30g soy cream cheese with 7-10g of olive oil or rice bran oil for a total of 10-15g total oil in a 900-1000g dough batch.  Because of this process, I rarely use preferments anymore.  Some may consider that cheating, but by some standards, so is letting someone else grow your wheat and mill it for you too.

- red.november


Offline scpizza

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Re: fermentation
« Reply #21 on: February 12, 2007, 06:54:00 PM »
You may want to keep your yeast away from your starter when you have the starter at 33 C, or use extremely miniscule amounts.

Thanks for your response, however, it is confusing to me.  We may be defining terms differently.  I'm defining "starter" (Ischia in this case) as a culture containing both bacteria (L. Sancrancisenis) and yeast (C. Milleri).  There is no other yeast involved in my experiment other than the C. Milleri cells present in my starter.

Agreed that culturing at 5C will favor bacteria at the expense of yeast, but so will culturing at 33C.  At either temperature after several refreshments the yeast should be in the minority in the starter by my reckoning. 

Also I don't agree with your comment that by lowering the temperature from 33C to 25C less lactic acid is produced.  At 25C the bacteria and yeast grow at about the same rate.  It is at temps from 25C-40C that the bacteria grow faster.

Even though I cultured my starter at 33C, I rose my dough at 25C because I figured the starter was so heavily skewed to the bacteria side to start with, that letting the bacteria and yeast yeast rise at 25C would simply keep that imbalanced state preserved as each bug grew at the same rate.  I didn't want to obliterate the yeast entirely.

Plus I read somewhere that no cell division happens in the anaerobic environment of the dough, that oxygen is required for that, though of this I am not very confident.

I am still not sure why my experiment skewing the starter cell population toward the lactic bacteria did not produce the stronger lactic acid taste I was hoping it would.

Thanks for your perspective on the lactic vs acetic acid taste question.  I didn't appreciate the different chemical properties of each.  Fascinating story about refrigerated food lacking the same taste as room temp food.  Wonder why cold pizza tastes so good then? :)

And yes, your addition of lactic acid saturated foodstuffs to pizza dough is total cheating!

Offline November

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Re: fermentation
« Reply #22 on: February 12, 2007, 08:11:19 PM »
Thanks for your response, however, it is confusing to me.  We may be defining terms differently.  I'm defining "starter" (Ischia in this case) as a culture containing both bacteria (L. Sancrancisenis) and yeast (C. Milleri).  There is no other yeast involved in my experiment other than the C. Milleri cells present in my starter.

I was talking about starters in general.  Again, I don't know how much yeast is in your starter, but in general, at that temperature yeast will be active enough to consume the nutrient supply to such a degree that bacterial activity will be impaired.

but so will culturing at 33C.

Not without provisions, at that temperature the yeast will be quite active.  Growth rates don't necessarily translate to metabolic exchange rates.  Just because the optimum temperature for C. Milleri is about 27 C, and 33 C for L. Sancrancisenis, it doesn't mean you will achieve a dough with a disproportionately larger quantity of lactic acid.  Because of how much more yeast consumes on a per-cell basis, the minor growth rate difference at 33 C will not not be enough to allow the bacteria to thrive as much in the presence of yeast.  If your culture has a significantly small amount of C. Milleri, or your washing is effective in meeting your desired end, then you're set to incubate at 33 C.

Also I don't agree with your comment that by lowering the temperature from 33C to 25C less lactic acid is produced.

Your disagreement is misplaced.  I never said less lactic acid is produced; nevertheless, assuming bacteria is less active at 25 C versus 33 C, I don't see from where the source of your disagreement stems.

At 25C the bacteria and yeast grow at about the same rate.  It is at temps from 25C-40C that the bacteria grow faster.

Growth at the same rate, yes, but not necessarily produce the respective acids at the same rate; and even that is assuming the nutrient supply holds up for both.

Plus I read somewhere that no cell division happens in the anaerobic environment of the dough, that oxygen is required for that, though of this I am not very confident.

That is not exactly correct.  Yeast budding happens at a greatly decreased rate in an anaerobic environment, but it doesn't stop entirely.

Wonder why cold pizza tastes so good then? :)

Although I eat cold pizza on very regular basis, I would have to say that is a matter of opinion.

And yes, your addition of lactic acid saturated foodstuffs to pizza dough is total cheating!

So be it.  I don't have a problem with experimentation for the sake of gaining knowledge, but I have better things to do than spend time on starters all the time.  I'm sure there are many who think buying yeast cultures is cheating.

- red.november

Offline scpizza

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Re: fermentation
« Reply #23 on: February 12, 2007, 09:50:05 PM »
Growth rates don't necessarily translate to metabolic exchange rates.  Just because the optimum temperature for C. Milleri is about 27 C, and 33 C for L. Sancrancisenis, it doesn't mean you will achieve a dough with a disproportionately larger quantity of lactic acid.  Because of how much more yeast consumes on a per-cell basis, the minor growth rate difference at 33 C will not not be enough to allow the bacteria to thrive as much in the presence of yeast.
Even if the yeast consume far more on a per-cell basis, shouldn't the lactic acid / acetic acid ratio increase if you get more L. Sanfranciscensis cells?

It seems you are saying even though the L. Sanfranciscenis is growing disproportionately faster at 33C than C. Milleri, we still don't see a higher lactic acid / acetic acid ratio because the yeast cells that are there are much more metabolically efficient at 33C than 25C and thus able to hog the sugars even in the face of increasingly larger numbers of L. Sanfranciscenis.

I have assumed that replication rate changes are proportional to metabolic rate changes.  Replication is directly linked to energy availability is directly linked to metabolic rate is directly linked to by-product production.  If that assumption is mistaken, then I can see why I might not get a greater lactic acid / acetic acid ratio at the higher temperature.

I do see you agree with me that at some point after enough washings the C. Milleri would just be so numerically overwhelmed by the L. Sanfranciscenis that I could then achieve the higher lactic acid / acetic acid ratio.

Your disagreement is misplaced.  I never said less lactic acid is produced; nevertheless, assuming bacteria is less active at 25 C versus 33 C, I don't see from where the source of your disagreement stems.
I was disagreeing with your statement that "By lowering your temperature to 25 C, you created conditions where comparatively speaking, less acetic acid is produced."  Does "comparatively" mean compared to acetic acid at 33C or to compared to lactic acid?  I definitely agree with the former.  But as I mention above, the latter is very counterintuitive.

That is not exactly correct.  Yeast budding happens at a greatly decreased rate in an anaerobic environment, but it doesn't stop entirely.
This makes sense to me.  From a survival basis it just makes sense that both of these bugs need to be able to replicate in an anaerobic environment.
« Last Edit: February 12, 2007, 09:55:09 PM by scpizza »

Offline November

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Re: fermentation
« Reply #24 on: February 12, 2007, 11:23:10 PM »
Even if the yeast consume far more on a per-cell basis, shouldn't the lactic acid / acetic acid ratio increase if you get more L. Sanfranciscensis cells?

You're assuming that the L. Sanfranciscensis cell count increases at an optimal rate in the presence of yeast.  It doesn't.  Both its growth and metabolic exchange rate is very much dependent on the nutrient supply - a supply which the yeast competes for.  Yet again I stress that all of this still depends on what the initial cell count ratio is between the yeast and bacteria.  If the bacteria are outnumbered to begin with, there isn't much room for bacterial activity, metabolic or growth.

It seems you are saying even though the L. Sanfranciscenis is growing disproportionately faster at 33C than C. Milleri, we still don't see a higher lactic acid / acetic acid ratio because the yeast cells that are there are much more metabolically efficient at 33C than 25C and thus able to hog the sugars even in the face of increasingly larger numbers of L. Sanfranciscenis.

Once again, it comes down to the initial ratio between the two and nutrient availability, but also washings over time.

I have assumed that replication rate changes are proportional to metabolic rate changes.  Replication is directly linked to energy availability is directly linked to metabolic rate is directly linked to by-product production.

That is not a solid assumption to make.  Waste products from organisms at any level of complexity change variably with stages of life.  You can tell the difference between the fecal matter and urine from a human infant, 30-year-old, pregnant mother, and dying 85-year-old, because when an organism is growing, maintaining, reproducing, or dying, it is producing a different kind of waste.  The cell growth and reproductive processes also absorb compounds and reserve producing certain chemicals that would not necessarily happen in cases of cell maintenance or dying.  Reproduction is also directly linked to acidity for bacteria, which does not affect metabolism in the same way.

I do see you agree with me that at some point after enough washings the C. Milleri would just be so numerically overwhelmed by the L. Sanfranciscenis that I could then achieve the higher lactic acid / acetic acid ratio.

It could take a lot of washings though.

I was disagreeing with your statement that "By lowering your temperature to 25 C, you created conditions where comparatively speaking, less acetic acid is produced."  Does "comparatively" mean compared to acetic acid at 33C or to compared to lactic acid?  I definitely agree with the former.  But as I mention above, the latter is very counterintuitive.

I don't see how it matters what I was comparing.  I said less acetic acid, not less lactic acid.  Even if I were comparing it to the lactic acid, that doesn't mean there's less lactic acid.  In fact, it would imply there's more lactic acid relative to acetic acid.  Anyway, you were comparing the results between two temperatures, so I followed suit.  However, I still don't know why you object to there being less lactic acid as a result of a lower temperature.  The comparison has remained between 25 C and 33 C results.

- red.november

Offline scpizza

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Re: fermentation
« Reply #25 on: February 13, 2007, 08:20:12 AM »
Your comments on waste products is fascinating.  I had never pondered the difference in waste composition depending on bacteria/yeast state of being and phase of lifecycle - and that impacting crust flavor.   Would be a very interesting set of trials to make batches of doughs with normal, stressed, happy, dividing, stagnant organisms and do blind taste tests to see exactly how and to what extent these can be tasted by humans in finished pizza crust.

On the temperature/replication/metabolism bit the picture does seem more complicated than I originally assumed and I appreciate your pointing out where my assumption was too simple.  You also make a very good point that a simple temperature vs. growth curve made for an organism alone in media does not apply very cleanly to that organism when it is in a culture with another organism in a symbiotic relationship.

However, I still feel it is counterintuitive than when I get a higher concentration of one beastie in a mix, I will not see a higher ratio of its namesake waste product.  Perhaps an answer is that the dominant constraint on L. Sanfranciscensis is not temperature, nor sufficient population, but nutrient availability.  If the yeast rapidly consume nearly all the nutrients themselves like lordly masters, then dole out meager allocations of maltose to keep the lactobacillus alive, then I could see how having more lactobacillus around wouldn't appreciably change the lactic / acetic acid ratio because metabolic activity is being constrained by food provided by the yeast cells, not temperature nor number of bacteria.

My objection to there being less acetic acid (versus lactic) at a lower temperature stemmed from my knowledge that lactobacillus grow faster at higher temperatures, and an article I read that explicitly said you would get more lactic acid in your culture if you grow it at higher temperatures.  These data points led me to believe there would be more acetic acid (versus lactic) at lower temperatures.

Offline November

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Re: fermentation
« Reply #26 on: February 13, 2007, 10:02:38 AM »
If the yeast rapidly consume nearly all the nutrients themselves like lordly masters, then dole out meager allocations of maltose to keep the lactobacillus alive, then I could see how having more lactobacillus around wouldn't appreciably change the lactic / acetic acid ratio because metabolic activity is being constrained by food provided by the yeast cells, not temperature nor number of bacteria.

Actually, conventional knowledge about Lactobacillus sanfranciscensis indicates that it produces glucose to help support Candida milleri.  Despite subtle symbiosis, there is still a great deal of antagonism though.  The antagonism is what keeps typical ratios at 1:100 for sourdough bread.  Yeast in any greater quantity will indeed take over under standard conditions.  Yeast cells are approximately 66 times the size of their bacterial neighbor.

My objection to there being less acetic acid (versus lactic) at a lower temperature stemmed from my knowledge that lactobacillus grow faster at higher temperatures, and an article I read that explicitly said you would get more lactic acid in your culture if you grow it at higher temperatures.  These data points led me to believe there would be more acetic acid (versus lactic) at lower temperatures.

That would be a whole other objection to what you originally stated.  "I don't agree with your comment that by lowering the temperature from 33C to 25C less lactic acid is produced."  Yeast are also less active at lower temperatures, so levels of both acids will drop, but because it's is a stronger (palate) acid, a drop in acetic acid will be more noticeable.  That was the point I was making.

Happy fermenting.

- red.november

EDIT: By the way, how much the two organisms compete for food will depend on what you feed your starter.  If all you're giving them is flour, they're on fairly even ground.  I have to admit that part of why I mentioned the food source competition is because I have always fed my starter/preferments molasses in order to support healthy growth.  L. sanfranciscensis and C. milleri both compete for sucrose.  If you're feeding them malt syrup, L. sanfranciscensis will have the upper hand.  Perhaps you should try that if you are not already doing so.
« Last Edit: February 13, 2007, 10:25:57 AM by November »

Offline Bistro

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Re: fermentation
« Reply #27 on: October 08, 2007, 09:45:55 PM »
November
could you post the dough recipe you use with the Better than cream cheese and olive oil. And you recommend using the Caputo 00 for the dough? Thank you for your time and I have enjoyed reading your posts on all the aspects of pizza making.
Mystie

Offline aptfive

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Re: fermentation
« Reply #28 on: October 09, 2007, 12:09:59 AM »
...this is a great thread ..in my home fridge ..doughs that i let ferment 3,4 and even 5 days always taste much better

Offline November

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Re: fermentation
« Reply #29 on: October 09, 2007, 03:48:13 PM »
November
could you post the dough recipe you use with the Better than cream cheese and olive oil. And you recommend using the Caputo 00 for the dough? Thank you for your time and I have enjoyed reading your posts on all the aspects of pizza making.
Mystie


I don't usually have dough formulas that are specific to additives like Better Than Cream Cheese.  I just add those ingredients in proportion to how much fat or sugar I want in the dough.  For instance, if I only want 1% fat in my dough, I would add 5.6% Better Than Cream Cheese.  I treat it just like an oil.  You can use any preexisting dough formula to see if it's something you like.  A formula that I've used extensively can be found here: http://www.pizzamaking.com/forum/index.php/topic,5028.0.html

I haven't recommended using Caputo 00, but I don't recommend against it either.  I was simply answering a question about it.  Typically you would use Caputo 00 only if you're interested in that kind of crust, usually fermented at room temperature and baked at higher temperatures.

- red.november
« Last Edit: October 09, 2007, 03:49:49 PM by November »


Offline sourdough girl

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Re: fermentation
« Reply #30 on: October 09, 2007, 04:26:34 PM »
red.november
If you would be so kind... I have been reading a lot about fermentation, yeast and it's symbiotic relationship with various bacteria... and am working to nurture my own wild yeast.  DH and I both prefer assertively sour bread and a-little-less-so pizza crust.  In reading various authors (Ed Wood, Peter Reinhart and others) it seems there is some disagreement on how to develop that sour tang.  I don't want it to bite me back, but I want to develop an assertive tang like San Francisco breads.  Since I want to use my starter for both bread and pizza crust, what would you suggest as a rule of thumb concerning temperature, possible "...ose" additives, etc for developing a more sour flavor?  You have science on your side much moreso than the authors listed above, so thought maybe another opinion would be helpful!

Another thought just occured to me... does whole grain flour make a difference?  I have light and dark rye flours as well as KA white whole wheat, but have been using GM AP to get things rolling.  Thoughts?

Thanks in advance!
~sd
« Last Edit: October 09, 2007, 04:34:41 PM by sourdough girl »
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Offline November

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Re: fermentation
« Reply #31 on: October 09, 2007, 06:11:48 PM »
sourdough girl,

I would recommend a fermentation temperature of 30C (86F) if you're trying to get a good balance of acids, but if you're interested in more lactic than acetic, try cooler temperatures for longer periods, and increase the maltose in your dough.  If you're interested in more acetic than lactic, aerate the dough more, ferment at temperatures greater than 30C, and use less (or no) extra maltose.  Just as one would expect based on organic chemistry, when oxygen is aplenty, alcohol is oxidized to acetic acid to provide additional energy for the yeast.  Lactic acid levels are not affected by the amount of oxygen in the dough to the same degree.

You could also just do what I do from time to time: add lactic or malic acid.  If you want to get that sour flavor the old-fashion way, you just have to be patient with your starter.

Any kind of flour or additive that supplies extra micro-nutrients will make a difference.  If you plan to create the sour flavor through your starter, I would recommend using something like molasses and/or malt syrup to supply the nutrients though.  The added fat in whole grain flour will oxidize over that longer period of time, depriving the yeast of that oxygen.  If it's just going to be a preferment, whole grain flour is fine for adding extra micro-nutrients.

- red.november

Offline sourdough girl

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Re: fermentation
« Reply #32 on: October 11, 2007, 06:49:27 PM »
red.november,
Thanks for the informative reply.  From some of my reading, it seems that acetic acid is more volatile and therefore, beyond the pH factor of sourness, is more available to nose and taste buds as a flavor agent.  From this, I would assume that if I want more sour bread, I should work to develop the acetic acid over the lactic.  Is that a reasonable assumption, or is it too simplistic?  One source suggests a 20/80 ratio of acetic/lactic, but, other than sending a sample off to a lab, I have no idea how I would know what the ratio might be, nor do I think I need to get that scientific.  I am hoping that my assumption is correct... and I am taking complete notes as to each step in my procedure. 

I appreciate your help in the learning process.

~sd
Never trust a skinny cook!

Offline November

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Re: fermentation
« Reply #33 on: October 11, 2007, 07:27:29 PM »
sourdough girl,

From a study published by the American Society for Microbiology years ago, the average ratio for sourdough is about 1:2.43; acetic:lactic for fully developed bread, and about 1:2.18 for the starter.  I wouldn't worry too much about the exact amounts of each.  It sounds like what you want may be a bit different from the average sourdough anyway.  I would suggest caring for your starter in such a way as to promote bacterial growth by default, taste the results, and if you think it needs more acetic acid, aerate the starter to promote increased acetic acid production.

- red.november

Offline November

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Re: fermentation
« Reply #34 on: October 11, 2007, 07:42:56 PM »
From this, I would assume that if I want more sour bread, I should work to develop the acetic acid over the lactic.


As I'm sure you are aware, there are different kinds of sour.  If you really want to know what ratio to aim for, consider mixing just the acids together to get an idea of what you think tastes best.  You can obtain calcium lactate (in place of lactic acid) pretty easily from several places online, and possibly at your local pharmacy or health food store.  Acetic acid, of course, can be had in the form of vinegar.

- red.november

EDIT: An example source: http://www.iherb.com/ProductDetails.aspx?c=1&pid=477&at=0
« Last Edit: October 11, 2007, 07:45:18 PM by November »

Offline November

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Re: fermentation
« Reply #35 on: October 11, 2007, 08:02:53 PM »
Since the subject of flavor perception comes up a lot on this forum, I'm going to provide a link to one of the most valuable research points of interest available for free (most of the time) on the Internet.

http://chemse.oxfordjournals.org/

Just search for what kind of flavor or chemical you are wanting to see articles on.

- red.november