Carotenoid, chlorophyll and chlorophyll-derived compounds in pistachio kernels (pistacia vera l.) from Sicily

The composition of carotenoid, chlorophyll, and chlorophyll-derived compounds in Sicilian pistachio kernels (Pistacia vera L.) was investigated. In all, 13 compounds were identified and quantified using reversed-phase liquid chromatography with photodiode array detection with a C-30 column. Internal kernel colour is an important visual quality characteristic for the food processing industry. Chlorophyll a was the major component (54.14 ppm), followed by chlorophyll (30.2 ppm). Lutein (29.14 ppm) and pheophytin a (25.68 ppm) were also well represented. Pheophytins a and b, neoxanthin, luteoxanthin and violaxanthin were identified in pistachio nuts for the first time. The presence of a carotenoid ester was also detected. The ratio between the two isochromic pigment fractions, namely the chlorophyll and the carotenoid fractions, was 2.7, clearly showing the prevalence of the green colour; the chlorophyll a/chlorophyll b and the lutein/beta-carotene ratios were of 1.8 and 4.1, respectively. These parameters, along with other analytical parameters, could be used as indicators of typicality in Sicilian pistachio nuts. The presence of a specific pigment profile in nuts could, in fact, be used to guarantee the typicality of the product, since the quality control of food also requires a precise knowledge of the pigment composition of the original product.