Morphological characterization and determination of pungency in Capsicum spp

Peppers belong to the genus Capsicum, and include about 30 species, whose cultivation is widespread due to their rich content in vitamins and capsaicinoids, responsible for their pungency. Quantification of pepper pungency is important for the consumer, as a base ingredient in food preparation, for pharmaceutics formulation, and for the global industry market. The purpose of this paper is the identification of species in a population of 71 plants from various countries, grown in plastic pots at the Instituto Superior de Agronomia, Portugal, and the quantification of capsaicinoid content with subsequent determination of fruit pungency in Scoville Heat Units (SHU). For the identification of species, accessions of Capsicum were morphologically characterized, using descriptors according to the guidelines of the Community Plant Variety Office and others from the International Plant Genetic Resources Institute. Morpho-physiological characterization lead to the identification of samples in a population that included all five cultivated species: 32 C. annuum, 5 C. baccatum, 27 C. chinense, 6 C. frutescens and 1 C. pubescens. The record of the descriptors of each plant was performed from seed to fruit maturity, aiming not only the identification of the species but also the determination of a narrower group of more useful characteristics that would allow that identification. Results of hierarchical cluster analysis showed that the most useful characteristics needed for the correct identification are: seed and corolla color, presence of spots on petals, and the presence or absence of ring constriction. Capsaicinoids were quantified by HPLC. Values between 88 and 14,814 mg kg-1 were registered for capsaicin, and between 4 and 5860 mg kg-1 for dihidrocapsaicin, resulting in a range of 1417 SHU for C. annuum ‘Padrón’ to 324,928 SHU for C. chinense ‘Scotch Bonnet’. No direct relationship between pungency and species was found, although C. chinense reached the highest levels.