Capsaicin and Dihydrocapsaicin Contents of Thai Chili Cultivars
Ten cultivars of Thai chilies, including six Capsicum annuum L. and four C. frutescens L. were grown under field conditions to determine their capsaicin and dihydrocapsaicin contents using high-performance liquid chromatography. The capsaicin content of the chili cultivars ranged from 0.76-3.76 mg/g and the dihydrocapsaicin content ranged from 0.59-2.39 mg/g. One C. frutescens cultivar (K07) and two C. annuum cultivars (Huayseeton SK1 and Huarua) had high capsaicin contents, while two C. annuum cultivars (Huarua and Pijit007) had high dihydrocapsaicin contents. The Huarua, Huayseeton SK1 and K07 cultivars had the highest capsaicinoid contents which were greater than 5.2 mg/g.
The Thai chili cultivars in this study, with the exception of K05, were classified as ‘highly pungent’ with a pungency range from 45,000-80,000 Scoville Heat Units (SHU). The Huarua and K07 cultivars were classified as ‘very highly pungent’ chilies with SHU values greater than 80,000. All chili
cultivars however, had a higher content of capsaicin than of dihydrocapsaicin. High capsaicin to dihydrocapsaicin ratios were found in the K07 and Huayseeton SK1 cultivars. Moreover, capsaicin and dihydrocapsaicin contents were highest in the first harvest in all cultivars and decreased in subsequent harvests.