Enlarge /. There might soon be an easier way to tell how hot this chili pepper is.
Capsaicin is the compound responsible for how hot a variety of chili peppers will be. The higher the capsaicin level, the hotter the pepper. There are several methods of quantifying how much capsaicin is in a pepper – its "spiciness" – but they are either too time consuming, too costly, or require specialized instruments, which makes them less than ideal for widespread use.
Now, a team of scientists from Prince of Songkla University in Thailand has developed a simple, wearable sensor device that can be connected to a smartphone to show how much capsaicin is in a given chilli pepper sample. This emerges from a new article in the journal ACS Applied Nanomaterials. Bonus: The device has a bizarre shape like a glowing chili.
An American pharmacist named Wilbur Scoville invented his Scoville scale of the same name as early as 1912 to assess the relative spiciness of chili peppers. This testing procedure involves dissolving an exact amount of dried pepper in alcohol to extract the capsaicinoids. The capsaicinoids are then diluted in sugar water. A group of five trained tasters then try multiple samples with decreasing concentrations of capsaicinoids until at least three of them can no longer sense the heat in a particular sample. The spiciness of the pepper is then rated based on its Scoville Thermal Units (SHU).
So hot right now
For example, the Scottish bonnet and habanero range from 100,000 to 350,000 SHU; Jalapeños fall in the 3,500-10,000 SHU range; and the humble pepper drops out at 0 SHU. Nowadays there are also a multitude of so-called "super hots" with heat ratings of over 1 million SHU, such as the Ghost Pepper (Bhut Jolokia) with 1.58 million SHU and the Naga Viper with 1.4 million SHU. In fact, there is fierce competition among chilli growers in the US, UK, and Australia over who can grow the hottest chilli pepper. The hottest SHU rating to date is an American strain called Pepper X, which hits a whopping 3.18 million SHU, although this has not been independently confirmed by Guinness World Records.
Here's one possible reason for the record breaking heat from superhots. In a 2015 study using fluorescence microscopy, it was found that super-hot varieties typically store as much capsaicin in the skin as it does in the pulp, unlike traditional chili peppers, where capsaicin is primarily stored in the pulp. While seasoned cooks know that removing the pulp and seeds while preparing peppers also dissipates a lot of their own heat, it doesn't work with super-hot varieties. It's also why seasoned chefs can handle superhots while wearing gloves and eye protection. A single seed can burn the skin.
The Scoville scaling method has one obvious drawback: it is quite subjective, so it lends itself to inaccuracies. In fact, it has been estimated that results from different laboratories can vary by up to 50 percent. For example, different people have different numbers of mouthwarm receptors and the palate can quickly become desensitized to capsaicinoids. This means that tasting several samples in a row can lead to sensory fatigue. In the last few years the focus has shifted to alternative methods such as high-performance liquid chromatography, gas chromatography, colorimetry or spectrophotometry.