Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: mdubois82 on 13/02/2009 08:52:35

Title: What makes wasabi "hot"?
Post by: mdubois82 on 13/02/2009 08:52:35: mdubois82 asked the Naked Scientists:

I love your show (http://www.thenakedscientists.com/HTML/podcasts/)...

If Capsaicin is the cause of spicy or hot in peppers, what is the hot in wasabi? Why is so different and are there other hots or spices?
What do you think?
Title: What makes wasabi
Post by: dentstudent on 13/02/2009 09:01:32: Wasabi is made from a type of radish similar to Horse radish.

I found this from Chowhound:

Constituents of wasabi

Isothiocyanates (ITCs) are a group of naturally occurring sulphur compounds responsible for the chracteristic flavour of wasabi.

The compounds are volatile and are evolved from plant tissues when they are disrupted e.g. in the preparation of food, grating, cutting, chewing etc. However, plant tissues do not contain ITCs but contain glucosinolates (GSLs), which are the precursors of ITCs. GSLs are a group of glucosides, stored within the cell vacuoles of all Crucifereaeplants.

GSLs coexist in plants, but are not in contact with the hydrolytic enzyme myrosinase in the intact cell. When plant tissues are mechanically disrupted or injured (e.g. by chewing, crushing or grating in the preparation of food) the enzyme is released from the cell wall, and in the presence of adequate moisture myrosinase rapidly hydrolyses the GSLs to yield glucose and an aglucone.

The organic aglucone is unstable and undergoes Lossen Rearrangement to produce sulphate and a variety of products. The nature of products is dependent on a number of factors, including the structure of GSL side chain, the reaction conditions (e.g. pH), the presence of cofactors (e.g., metal ions, specific protein), temperature and durationas well as the age and condition of plant tissues.

Isothiocyanates (ITCs) are formed from GSLs under neutral and alkaline conditions. However, GSLs, which contains a â-hydroxyl group (I in Figure 2) in their side chain, give rise to ITCs that spontaneously cyclise to form oxazolidinethiones. Some aromatic and heterocyclic GSLs (II in Figure 2) produce ITCs which are unstable at pH 7 or higher and break down to release the corresponding alcohol and inorganic thiocyanate ions.

However, once formed ITCs are more stable under acidic conditions. In weakly acidic pH’s or in the presence of Fe+2and/ or in presence of endogenous nitrile factor, nitriles are produced from aglucone by autolysis instead of ITC, with the liberation of elemental sulphur. The relative proportion of ITC to nitriles can vary widely depending upon the conditions of autolysis.

Different ITCs have been reported from previous investigations in wasabi and each ITC has a specific flavour profile and so the complete taste of wasabi derived from the combined tastes and odours of all the ITCs present .

HTH
Title: What makes wasabi
Post by: neilep on 13/02/2009 11:27:15: I luff wasabi and I luff sushi !
Title: What makes wasabi \
Post by: dentstudent on 13/02/2009 11:57:36: Me too! We make our own sushi...
Title: What makes wasabi
Post by: neilep on 13/02/2009 12:13:30: Quote from: dentstudent on 13/02/2009 11:57:36
Me too! We make our own sushi...

Oh my !!

I should fraternise with ewe more often, *perhaps I'll get an invite to a sushi party*

Looks fantastic !!!
Title: What makes wasabi
Post by: dentstudent on 13/02/2009 12:16:32: Thanks! Ewe're welcome anytime ewe're in the south of Germany!
Title: What makes wasabi
Post by: neilep on 13/02/2009 12:26:31: Quote from: dentstudent on 13/02/2009 12:16:32
Thanks! Ewe're welcome anytime ewe're in the south of Germany!

Well, it just so happens !!...DOH !!

And the courtesy is also reciprocated fella. North London welcomes you and yours too ! [;)]
Title: What makes wasabi \
Post by: dentstudent on 13/02/2009 12:42:57: [:)] [8D] [^]
Title: What makes wasabi
Post by: Astronomer_FB on 18/02/2009 11:08:02: Why does it burn to breathe through your noise when eating wasabi because when i eat it, and i eat alot i breathe through my mouth to negate the spice.
Title: What makes wasabi
Post by: Chemistry4me on 19/02/2009 04:50:31: Quote from: Astronomer_FB on 18/02/2009 11:08:02
Why does it burn to breathe through your noise when eating wasabi
Nose?
You mean hot as in chilly hot or not cold hot?
From what I can remember, all I get is hot air (not spicy hot) through my nostrils.
Title: What makes wasabi
Post by: Astronomer_FB on 20/02/2009 23:29:03: Quote from: Chemistry4me on 19/02/2009 04:50:31
Quote from: Astronomer_FB on 18/02/2009 11:08:02
Why does it burn to breathe through your noise when eating wasabi
Nose?
You mean hot as in chilly hot or not cold hot?
From what I can remember, all I get is hot air (not spicy hot) through my nostrils.

well it is burning like you are tearing out face red hot and spicy. Once i ate a bowl of wasabi for $5 i was on the last bit and i laughed becaUSE of my bro and i breathed through my nose and Ifelt all the wasabi pain it hurt so bad.
Title: What makes wasabi
Post by: Chemistry4me on 20/02/2009 23:36:19: You ATE a BOWL of WASABI!?!?!?! [:0][:0]
Title: What makes wasabi
Post by: Chemistry4me on 20/02/2009 23:40:57: No wonder why you had flaming nostrils! [::)]
Title: What makes wasabi
Post by: Astronomer_FB on 22/02/2009 14:55:25: Quote from: Chemistry4me on 20/02/2009 23:36:19
You ATE a BOWL of WASABI!?!?!?! [:0][:0]
For $5 lol, but try eating wasabi without breathing through your nose it will feel weird and i still find it weird and i have been doing it for awhile. You will not feel the spice at all or just a little bit.
Title: What makes wasabi
Post by: Chemistry4me on 23/02/2009 02:52:23: Does it kind of feel like eating toothpaste?
Title: What makes wasabi
Post by: Astronomer_FB on 04/03/2009 00:53:32: Quote from: Chemistry4me on 23/02/2009 02:52:23
Does it kind of feel like eating toothpaste?
when i eat wasabi i eat it differently then any other kind of eating i do i kind of semi open my mouth to breathe from and it feels like chewing gum sorda