Any organic chemists here?

[Shaun @ Tru6]

I want to modulate the effect of capsaicin in peppers. I took orgo 25 years ago and couldn't tell an alkane from alkene today. The key is keeping the taste of the pepper while reducing the heat, so only modifying the capsaicin molecule.

Any ideas?

[onlycafe]

take out the seeds and veins.
no chemistry needed.

[nostatic]

That probably doesn't contribute much to the flavor - that gives the heat. If you modified the molecule you'd likely lose that effect (you can see that with variants like the dihydro).

The biggest target of opportunity is the double bond on the terpenoid end. That gets reduced in dihydro (which is just a bit less heat). The chain length has an effect - an extra carbon atom cuts the heat in half. Easiest would be to oxidize the double bond to an alcohol but I bet you'd lose the heat completely as it wouldn't bind the receptor nearly as well, and would become a lot more water soluble.

[SilberUrS6]

Originally Posted by nostatic

That probably doesn't contribute much to the flavor - that gives the heat. If you modified the molecule you'd likely lose that effect (you can see that with variants like the dihydro).

The biggest target of opportunity is the double bond on the terpenoid end. That gets reduced in dihydro (which is just a bit less heat). The chain length has an effect - an extra carbon atom cuts the heat in half. Easiest would be to oxidize the double bond to an alcohol but I bet you'd lose the heat completely as it wouldn't bind the receptor nearly as well, and would become a lot more water soluble.

That would be the easiest reaction. Doing that on a cellular level would be the goal - if you could disable the machinery that makes the molecule, you could prevent it from being made in the first place. Since bell peppers don't make the stuff, you have the negative model. Since it is a secondary compound, disabling the molecular machinery that makes it probably would not affect the rest of the plant's essential machinery.

Doing organic chemistry outside of the plant would pretty much ruin the rest of the pepper, so you're probably stuck doing some sort of genetic work after discovering the biochemistry of the molecule's production. Since the molecule is pretty stable, hydrolyzing that double bond might be fairly simple, but the byproducts would not be edible. Well, the hydrolyzed molecule, sure But the leftover reactants? No so much.

[ChemMan]

Purely from a synthesis standpoint, if you are trying to maintain the length of the molecule but get rid of the db, you can hit it with H2 and a transition metal catalyst like Pt or Pd. It will change the bond angle from 180 deg to 109.5 deg. What effect that will have on the taste receptors I have no idea. DB can also be cleaved using O3 and dimethyl sulfide......just thoughts

[SilberUrS6]

Originally Posted by ChemMan

Purely from a synthesis standpoint, if you are trying to maintain the length of the molecule but get rid of the db, you can hit it with H2 and a transition metal catalyst like Pt or Pd. It will change the bond angle from 180 deg to 109.5 deg. What effect that will have on the taste receptors I have no idea. DB can also be cleaved using O3 and dimethyl sulfide......just thoughts

Yeah, but both of those things would render the rest of the pepper somewhat inedible, right?

I think that the ozone treatment might work on the aryl group too, but I doubt the metal catalyst/hydrogen treatment would do much there. And IIRC, platinum is a little more gentle than palladium.

[sammyg2]

Originally Posted by nostatic

That probably doesn't contribute much to the flavor - that gives the heat. If you modified the molecule you'd likely lose that effect (you can see that with variants like the dihydro).

The biggest target of opportunity is the double bond on the terpenoid end. That gets reduced in dihydro (which is just a bit less heat). The chain length has an effect - an extra carbon atom cuts the heat in half. Easiest would be to oxidize the double bond to an alcohol but I bet you'd lose the heat completely as it wouldn't bind the receptor nearly as well, and would become a lot more water soluble.

Or, you could hit it with a hammer!
mech eng.

[Pazuzu]

Based on my experience, if you take your hot peppers and plant them next to your mild peppers, you get random peppers that look mild but are really hot, and vice versa...

My pepper garden is a virtual biological museum, but they grow so damned well down here I can't stop! I'm sure I've made a pepper or two that had no capsaicin...

[Shaun @ Tru6]

Great info, thank you all!

So maybe I should start with getting some habanero and orange pepper plants and see what I can do. Plenty of bees around here in the spring time but I could probably cross-pollinate myself this winter.

I want all the flavor of a habanero but a lot less heat. Made a peach-habanero chutney once that tasted great, but needed more sugar than I would have liked, and wanted more habanero flavor.

[SilberUrS6]

Originally Posted by sammyg2

Or, you could hit it with a hammer!
mech eng.

Hot pepper puree!

Excellent for hot wings. Seriously.

[pete3799]

Originally Posted by ChemMan

Purely from a synthesis standpoint, if you are trying to maintain the length of the molecule but get rid of the db, you can hit it with H2 and a transition metal catalyst like Pt or Pd. It will change the bond angle from 180 deg to 109.5 deg. What effect that will have on the taste receptors I have no idea. DB can also be cleaved using O3 and dimethyl sulfide......just thoughts

Took the words right out of my mouth

[M.D. Holloway]

The heat is created by the cleaving of the sulfur bonds of the proteins in your mouth. Inflammation ensues...

[nostatic]

Originally Posted by M.D. Holloway

The heat is created by the cleaving of the sulfur bonds of the proteins in your mouth. Inflammation ensues...

What source says that? There isn't anything on the molecule that would reduce disulfides - it is binding a receptor protein that depolarizes the membrane.

"Capsaicin produces pain by selectively activating polymodal nociceptive neurons. This involves a membrane depolarization and the opening of a unique, cation-selective, ion channel which can be blocked by ruthenium red. The capsaicin-induced activation is mediated by a specific membrane receptor which can be selectively and competitively antagonised by capsazepine. Repetitive administrations of capsaicin produces a desensitization and an inactivation of sensory neurons. Several mechanisms are involved. These include receptor inactivation, block of voltage activated calcium channels, intracellular accumulation of ions leading to osmotic changes and activation of proteolytic enzyme processes."

Unless the last reference is to a reductase or thioredoxin (which aren't really proteolytic).

[M.D. Holloway]

Capsaicin – the active ingredient in spicy food – binds to a special class of vanilloid receptor inside our mouth called VR1 receptors. After capsaicin binds to these receptors, the sensory neuron is depolarized, and it sends along a signal indicating the presence of spicy stimuli.

But here’s the strange part: VR1 receptors weren’t designed to detect capsaicin. They bind spicy food by accident. The real purpose of VR1 receptors is thermoreception, or the detection of heat. This means that they are supposed to prevent us from consuming food that will burn our sensitive flesh. (That’s why our VR1 receptors are clustered in our tongue, mouth and skin.) As a result, when the receptors are activated by capsaicin, the sensation we experience is indelibly linked to the perception of temperature, to the feeling of eating something near the boiling point of water. But that pain is just an illusory side-effect of our confused neural receptors. There is nothing “hot” about spicy food.

The larger point, of course, is that vast swaths of the reality we take for granted are mere accidents of anatomy. We can’t help but believe in the “hotness” of chilis – the pain is so visceral – but that belief is an illusion. And so, every time I eat spicy food I think for a second about what other perceptions I’m taking too literally. Which of my cinematic sensations can I actually trust? And then I go back to chugging water.

I still think there is protein damage which brings about site inflammation which triggers histamine production...but I could be wrong...

[SilberUrS6]

Originally Posted by M.D. Holloway

I still think there is protein damage which brings about site inflammation which triggers histamine production...but I could be wrong...

The problem is that the disulfide bond, while being pretty darn weak, won't be affected at all by that molecule. You need something a bit stronger than that to rupture the bond.

[M.D. Holloway]

Ok so if it's not cleaving the disulfide in the protein then it's all about the taste receptors right?

If that's the case then the rectum has taste buds!!!

[SilberUrS6]

Originally Posted by M.D. Holloway

Ok so if it's not cleaving the disulfide in the protein then it's all about the taste receptors right?

If that's the case then the rectum has taste buds!!!

Not taste. Read what he wrote. It has nothing to do with taste.

[M.D. Holloway]

Capsaicin – the active ingredient in spicy food – binds to a special class of vanilloid receptor inside our mouth called VR1 receptors. After capsaicin binds to these receptors, the sensory neuron is depolarized, and it sends along a signal indicating the presence of spicy stimuli.

this?

[SilberUrS6]

Originally Posted by M.D. Holloway

this?

Yup.

Not taste.

[flatbutt]

How about a different approach, albeit beyond the reach of a kitchen chemist? If we were to analyze the volatiles in the headspace using cap GC / MS detection, that should give us a lead into the flavor. Then again maybe IFF and Firmenich already have that worked out. It'd be a fun project.