Heat profiles of ‘superhot’ and New Mexican type chile peppers (Capsicum spp.)

Abstract

Breeding for capsaicinoid content is one of the major objectives for chile pepper breeding programs due to its culinary, agricultural, and medicinal uses. The objectives of the current study were to determine the Scoville Heat Units (SHU) of select New Mexico State University (NMSU) chile pepper varieties and ‘superhot’ genotypes using high-performance liquid chromatography, and to verify the feasibility of using capsaicinoid content as a taxonomic indicator for the ‘superhot’ varieties. Significant variation (P < 0.001) for fruit heat level across the different growing seasons was observed. In the 2013 trial, ‘Trinidad Moruga Scorpion’ showed the highest mean SHU (∼1.41 million) among the ‘superhot’ varieties evaluated, although not-significantly different with that of the ‘Carolina Reaper’ (∼1.34 million). ‘NuMex Heritage Big Jim’ had a higher SHU (1759) compared to ‘NuMex Joe E. Parker’ (875) in the 2018 growing season. In the 2019 trial, ‘NuMex Sandia Select’ (7696) was observed to have a significantly greater mean SHU compared to ‘NuMex Heritage Big Jim’ (1581). The NMSU varieties have mild to moderately hot heat levels reflecting the current efforts to breed for less heat, but more flavorful and complex heat profiles for increased consumer acceptance. Using SHU exclusively was not able to discriminate the superhot cultivars for taxonomic purposes. Overall, diversity in terms of SHU for several cultivated and ‘superhot’ lines of chile peppers grown in New Mexico was observed. Information from this study could serve as a basis for future genomics-assisted breeding for the genetic improvement of heat levels of chile peppers in New Mexico.