Chile peppers (Capsicum sp.) are cultivated worldwide and are often prized for their heat (Bosland and Votava, 2012). A widely used heat measurement for chile peppers is the SHU (Scoville, 1912). This measurement is the highest dilution of a chile pepper extract at which heat can be detected by a human taste panel. Alternative instrumental methods have been developed since Scoville’s test. High-performance liquid chromatography (HPLC) is the most accurate and efficient method (Collins et al., 1995).
Chile pepper heat, or the amount of capsaicinoids (a group of alkaloids unique to Capsicum sp. that cause a burning sensation when eaten) in a chile pepper pod, is dependent on the genetic makeup of the plant and the environment where it is grown (Zewdie and Bosland, 2000a). The heat level can vary significantly among plants of the same variety grown in a single field at the same time. When single plant heat levels of genetically identical chile pepper plants were compared with the field average, it was found that individual plants had heat levels as much as 78% higher than the field average, indicating the environment contributes significantly to chile pepper heat levels (Harvell and Bosland, 1997). Further research showed that fruit from different areas on the same plant had significantly different heat levels (Zewdie and Bosland, 2000b).
Heat level claims for chile peppers can be based on single fruit, single plants, or as an average of the variety as a whole. For the Guinness World Records, a single fruit is sufficient to set a record for some plants. However, for the chile pepper processing industry, an average heat level is more informative.
In 2007, Guinness World Records established ‘Bhut Jolokia’ chile pepper from the Assam region of northeastern India as being the world’s hottest chile pepper. The heat level was established in replicated trials with appropriate controls (Bosland and Baral, 2007). The heat level of ‘Bhut Jolokia’ at 1,001,304 SHU, broke the million-SHU heat level for the first time.
A chile pepper variety, Trinidad Scorpion, from Trinidad and Tobago has been reputed to be hotter than ‘Bhut Jolokia’. Currently, Guinness World Records recognizes ‘Butch T Scorpion’, grown by Butch Taylor in Australia, as the world’s hottest chile pepper at 1,463,700 SHU (Guinness Book of World Records, 2011). Other varieties from Trinidad and Tobago (e.g., ‘Trinidad Moruga Scorpion’, ‘Trinidad 7-pot Jonah’, and ‘Douglah Trinidad Chocolate’) have been reported as very high heat varieties (Adams and Mohammed, 2008). Some of the variety names (i.e., ‘Trinidad 7-pot Jonah’) allude to folklore that they are hot enough to spice seven pots of soup.
To conduct a scientifically valid test to determine the mean heat level of a chile pepper variety, an ample seed sample must be planted in replicated trials that include an appropriate control. A random sample of fruit from the replicated varieties should then be tested. In this manner, a statistically higher heat level could reasonably be considered hotter than the current hottest variety.
This study was undertaken to 1) compare the heat levels of ‘Trinidad Moruga Scorpion’, ‘Bhut Jolokia’, ‘Trinidad Scorpion’, ‘Douglah Trinidad Chocolate’, and ‘Trinidad 7-pot Jonah’ in a replicated field trial; 2) establish which chile pepper variety truly has the highest average heat level; 3) determine any differences among the varieties across the environment; and 4) determine the genetic relatedness of the chile peppers using molecular data.
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