Biochemical Characterization of Traditional Varieties of Sweet Pepper (Capsicum annuum L.) of the Campania Region, Southern Italy

Abstract

Bioactive compounds of different Campania native sweet pepper varieties were evaluated. Polyphenols ranged between 1.37 mmol g^-1 and 3.42 mmol g^-1, β-carotene was abundant in the red variety "Cazzone" (7.05 μg g^-1). Yellow and red varieties showed a content of ascorbic acid not inferior to 0.82 mg g^-1, while in some green varieties the presence of ascorbic acid was almost inconsistent. Interrelationships between the parameters analyzed and the varieties showed that ascorbic acid could represent the factor mostly influencing the antioxidant activity. Polyphenol profile was different among the varieties, with a general prevalence of acidic phenols in yellow varieties and of flavonoids in red varieties. Principal Component Analysis, applied to ascorbic acid, total polyphenols and β-carotene, revealed that two of the green varieties ("Friariello napoletano" and "Friariello Sigaretta") were well clustered and that the yellow variety "Corno di capra" showed similarity with the green varieties, in particular with "Friariello Nocerese". This was confirmed by the interrelationships applied to polyphenol composition, which let us to light on a clustering of several red and yellow varieties, and that mainly the yellow "Corno di capra" was closer to the green varieties of "Friariello".

Keywords: Capsicum annuum L.; antioxidant activity; ascorbic acid; biodiversity; polyphenols; statistical analysis; β-carotene.

Figure 1

Traditional sweet pepper varieties of the Campania region analyzed in the present work. Legend: (a) Papaccella liscia; (b) Sassaniello; (c) Cornetto di Acerra; (d) Corno di capra; (e) Corno Marconi (f) Papaccella Napoletana; (g) Friariello a sigaretta; (h) Friariello Napoletano; (i) Friariello Nocerese; (l) Cazzone. The photos were made by the authors.

Figure 2

Correlation analysis. Red and yellow varieties are indicated with red and yellow squares, respectively. Green varieties are represented with green squares, except samples of “Friariello Nocerese”, represented by green circles, to highlight that at least two (of three samples) resulted very similar to red and yellow samples.

Figure 3

PCA obtained considering β-carotene, ascorbic and total polyphenols. Yellow and red-colored symbols indicate the yellow and red varieties, respectively.

Figure 4

PCA obtained considering polyphenol composition. Yellow and red-colored symbols indicate the yellow and red varieties, respectively.

Figure 5

Distribution of phenolic acids and flavonoids and phenolic acids, respect to the molecules recognized by UPLC, in yellow, red and green traditional varieties of sweet pepper of the Campania Region. Varieties = CG: Cazzone, yellow; PNG: Papaccella napoletana, yellow; PLG: Papaccella liscia, yellow; CAG: Cornetto di Acerra, yellow; SG: Sassaniello, yellow; CCG: Corno di Capra, yellow; CMG: Corno Marconi, yellow; CR: Cazzone, red; PNR: Papaccella napoletana, red; PLR: Papaccella liscia, red; CAR: Cornetto di Acerra, red; SR: Sassaniello, red; CCR: Corno di Capra, red; CMR: Corno Marconi, red; FNAP: Friariello Napoletano, green; FNOC: Friariello Nocerese, green; FSIG: Friariello Sigaretta, green.