Perfil aromático en cuatro cultivares de ají dulce (Capsicum chinense) de Puerto Rico

Abstract

The genus Capsicum includes several species, including Capsicum chinense. known as sweet chili pepper or ají dulce in Puerto Rico. The aroma volatiles of Puerto Rican sweet chili peppers have not been previously studied. The objective of this research was to identify the volatile compounds responsible for aroma in the pericarp and seed/placenta of four recently developed sweet pepper cultivars: 'Amanecer', 'Pasión', 'Carnaval' and 'Bonanza'. Volatile compounds were extracted using two fibers of different polarities: a non-polar fiber, polydimethylsiloxane (PDMS), and an intermediate polar fiber of divenilbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS). Compounds were separated using Gas Chromatography techniques coupled to Mass Spectrometry (GC/MS), using two columns of different polarities: a polar column of Carbowax 20 M, and the column SPB-5 that allows the analysis of chemical substances in all polarity ranges. Volatile headspace compounds were identified using the database of the Wiley7 mass spectrometry library. The seed/placenta had a higher number of separated compounds compared to the pericarp. The SPB-5 column showed the highest separation of compounds in the pericarp fraction in all cultivars. In the seed/placenta fraction, use of the SPB-5 column resulted in a greater amount of separated compounds in the cultivars 'Amanecer' and 'Bonanza'; for cultivars 'Passion' and 'Carnival' this result was achieved by the Carbowax 20M column. For the PDMS fiber the number of separated compounds for the pericarp varied between 0 and 39 and for the seed/placenta, between 0 and 80, depending on the cultivar. The smallest separation was obtained in the cultivar 'Bonanza' in both fractions. The highest percentage of volatiles in ‘Amanecer’ generally belonged to the aldehyde, ester, carboxylic acid, and alcohol families as well as other unidentified chemicals. ‘Carnaval' and ‘Bonanza ' presented a greater number of compounds belonging to hydrocarbons of terpene and pyrazines compared to the other cultivars. The most aromatic cultivars in the pericarp fraction, based on volatile compound concentration, were ‘Bonanza’ and ‘Pasión’ with 16 and 39 compounds followed by the varieties ‘Amanecer’ (36 compounds) and ‘Carnaval’ (25 compounds). In the seed/placenta the most aromatic cultivars were ‘Pasión’ and ‘Amanecer’ III with 83 and 79 organic compounds followed by ‘Carnaval’ (41 compounds) and ‘Bonanza’ (44 compounds). In the pericarp of the four cultivars of sweet chili pepper, five major compounds were found in common (methyl salicylate, indole, α -copane, γ -himachalen and β -cubebeno) although these differed in abundance. There were nine compounds in common in the seed/placenta (α-copaene, β-cubebeno, γ-himachalen, α-Ylangeno, trans-β-farneseno, β-himachalen, δ- cadineno, β -patchouleno and 2-methyltridecano). The results of this research indicate that the sweet chili pepper cultivars possess different volatile compounds and compound concentrations. These differences likely impact differences in aroma and flavor among the four cultivars. This research documents the aromatic compounds in the pericarp and in the seed/placenta of the sweet pepper and serves as a point of reference for cultivar development in the future.