Identification of Volatile Flavor Constituents of the Peel (Flavedo) from Five Greek Citrus Varieties Cultivated in the Area of Arta
Citrus is one of the world's most important fruit crops with a total world production of approximately 105 million metric tons. The citrus fruit consists of the following fundamental parts: the flavedo (external colored part of the peel), the albedo (white internal part of the peel), the pericarp which contains the above mentioned parts, and the pulp containing the juices and the seeds, called endocarp. The flavedo is composed mainly of cellulosic material and contains other components such as essential oils, non-volatile fraction of the essential oil (paraffin waxes, steroids, fatty acids, flavones etc.), and additional components such as pigments, bitter compounds (limonin) and enzymes.
In the present study the volatile flavor constituents of the peel (flavedo) from five Greek citrus varieties cultivated in the area of Arta (Zambetakis lemon variety, Navelina oranges, Valencia oranges, Common orange variety and bitter oranges) have been characterized by headspace solid-phase microextraction (HS-SPME) in conjunction with gas chromatography - mass spectrometry (GC-MS). For HS-SPME method a 100-μm PDMS fiber coating was utilized. GC-MS separations of volatile compounds were made using a 60 m×320 μm I.D.×1 μm film thickness DB5 (non polar) column. Eighty two (82) compounds were totally identified in citrus peel samples. More specifically, a total of 52, 57, 54, 53 and 36 compounds were found in Zambetakis lemon variety, Navelina oranges, Valencia oranges, common orange variety and bitter oranges, respectively. The identified compounds belong to the group of esters, alcohols, aldehydes and mainly sesquiterpene hydrocarbons. Limonene was the most abundant component in all samples, followed by sabinene, β-pinene, β-myrcene and linalool.