Thursday, 20 October 2011

It’s too HOT. It’s too COLD, well actually it’s neither

This dilemma experienced by little red riding hood is something that can confuse a lot of people but in a different scenario.  

I’m sure those of you reading this are familiar with and sober enough to know with that we eat food through our mouths (I’ve witnessed intoxicated people often attempt to feed themselves through their cheeks).  Our taste buds have receptors that can detect certain chemicals mainly food, and relays this information to the brain. There are receptors that detect carboxylic acids which are found in products such as vinegar which have a sour taste to it, and alcohol (OH) and carbonyl (CO) groups which are characteristic for sweet and sugary foods. Although taste is mainly determined through the tongue, other senses such as smell and temperature contribute to the taste sensation. 

Thermoreceptors in the tongue work with the taste receptors and tell us if the food we are eating it hot or cold. Whilst this is an intelligent tool which contributes to the dining experience, it can also get confused. The thought occurred to me whilst eating at Nando’s, which is most days, why does my mouth and body feel the effects of heat even though the peri-peri sauce is not thermally hot? 

I’m sure some of you have also questioned this sensation (perhaps with other spicy foods) and also thought about why your mouth feels cold after eating a mint.

The Science bit
Capsaicin is the chemical name of the ‘hot’ component found in chilli’s. It binds to the thermo receptors found on the tongue. These receptors are called TRPV1 and are also present in pain sensing neurons. TRVP1 is a Calcium and Sodium ion channel which is activated by heat. Normally, the channel will open when the temperature is in between 37°C and 45°C which is above the normal body temperature of 37°C. The opening of this channel brings about an influx of the ions leading to action potential (electrical signal) which tells the brain that your mouth is hot. When capsaicin binds to TRVP1, e.g. after eating a chilli, it lowers the temperature at which the channel normally opens. This triggers the chemical and electrical cascade which then makes you think the food is thermally hot. Common actions used to cool down includes shouting out in pain, fanning your mouth with your hand and drinking more milk than a 1 year old baby ever has.

Similarly, the coolness experienced from eating softmints and chewing gum comes from menthol which is an organic compound found in the flowering plant mint. Menthol interacts with TRPM8 receptor which is also found, in the skin, lungs and prostate. *NOTE *attempting to inhale or insert menthol or menthol containing products  into the lungs or prostate gland is not advised *.The TRPM8 receptor is activated at temperatures dropping below 26°C or when it interacts with cooling agents. Activation of the receptor causes the influx of Sodium and Calcium ions. The sudden imbalance of ions causes an electrical signal which makes us think it's cold. Since menthol is a cooling agent, it activates these receptors and makes us feel cold when we use toothpaste, eat mints or accidentally spill methanol on our skin during labs. 

The experiment
Some of you may be thinking as I did ‘Would eating a mint and chilli at the same time cancel each other out’? Well I was curious to find this out. Unfortunately, textbooks and the internet yielded no answers meaning one thing... I had to find out, THE HARD WAY. I decided to use the strongest ingredients I had at my disposal, Nandos extra extra hot sauce and Trebors mints. I pored over the internet and text books once more to make sure my tongue would not get damaged in this pointless experiment. I finally came across the question “what happens when you have both peppers and mint in your mouth at the same time?” 

To my dismay, the only answer was “You Die”.

The death warning was ignored and I proceded with the experiment (I had a bucket, a glass of water and 999 on speed dial just in case). The mint was put into my mouth followed by a spoonful of Nandos sauce before closing my mouth and chewing.  

Another question posed to me was, "what happens if you eat a ‘cold’ chilli or a ‘hot’ mint?"
Whilst I knew the answer to the first, again I was curious about the 'hot' mint. I decided to heat up a mint in the microwave for 8 seconds and eat it. The resulting sensation for both experiments is difficult to explain and it has to be tried by those of you who are brave enough.

Whilst the above experiments were not necessary or entirely conclusive, it did bring the idea of how the taste of one chemical can be altered by another. If our sense of hot and cold can be tricked through chemicals which aren’t actually hot or cold, can we trick our brain into tasting chocolate while eating brussel sprouts? Sorry to disappoint but the answer to that is NO and anything that looks like brussel sprouts should not be deemed fit to eat. However, there is a chemical that is able to alter the taste of foods and drinks.

I believe in Miracles
Miracle fruit
Synsepalum dulcificum (I can barely pronounce this myself) is a plant found in West Africa and produces a berry known as the miracle fruit. This fruit contains an active ingredient, miraculin, which is able to sweeten the taste of foods including lemons and lime. When the flesh of the fruit is held in your mouth or rubbed against the tongue, it is thought that miraculin binds to and alters the sweet receptors on your tongue so they can interact with sour food as well. 

This effect can last up to an hour and will make raw lemons taste like lemonade. Other tastes noted whilst under the influence of the berry are:-
·         Lemon sorbet and Guinness tastes like chocolate sauce.
·         Vinegar tastes like apple juice.
·         Tabasco sauce tastes like ‘hot’ doughnut glaze.
 Whilst the benefits of this fruit seem only for entertainment purposes, it can be beneficial in some ways.

The fruit itself is not sweet but induces the sweet taste when eating sour foods. So it acts as a sweetener which would be hugely beneficial for diabetics and fatties due to its low sugar and calorie content. Diabetics can still enjoy sweet tasting meals without a worry of consuming too much sugar. With the increasing problem of obesity, miracle berry can be used in fulfilling the sweet tooth without eating sugary foods. The berry itself is quite expensive and has a short shelf life but, the frozen form has the same properties and a longer shelf life.  Although its properties make it a suitable additive, it has not been given the go ahead by whoever decides these things in the western world.

Whilst the berry gives people an excuse to put something in their mouth, its taste altering properties can be adapted to help in advancements in dietary medicine. Also, understanding how miraculin works can tell us more about the interaction between food and the taste buds, how the sensation of different flavours is interpreted by our brain and ultimately, the differences in taste between different people and cultures. 

So when life gives you lemons... just make sure you have this handy fruit to sweeten it up.

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