title: Characterization of Brazilian green propolis throughout the seasons by headspace GC/MS and ESI-MS.
abstract: BACKGROUND
  A screening of the chemical composition of eight commercial classes of raw Brazilian green propolis throughout the seasons was carried out. A multivariate exploratory analysis of chemical composition obtained by gas chromatography associated with mass spectrometry with headspace extraction (HS-GC/MS), and by mass spectrometry with electrospray ionization (ESI-MS) was carried out using principal component analysis (PCA).
  
  
  RESULTS
  Differences in the volatile and polyphenolic profiles of propolis samples were verified during the seasons. Within each season, the high quality commercial classes of propolis presented similar characteristics, while the low quality classes presented distinct compositions. In spring and summer, propolis of the trimming class, commonly considered of low quality by beekeepers, presented a composition similar to the superior quality propolis.
  
  
  CONCLUSIONS
  Seasonality influences the chemical composition of the commercial classes of raw Brazilian green propolis. Headspace-GC/MS and ESI-MS assisted by PCA are effective to characterize volatile and non-volatile compounds of the propolis samples, and to correlate it to the seasons.
authors.affiliation: Department of Chemistry, Federal University of Lavras, CP 3037, CEP 37200-000, Lavras, MG, Brazil.
authors.forename: Cleiton A
authors.initials: CA
authors.lastname: Nunes
authors.forename: Mário C
authors.initials: MC
authors.lastname: Guerreiro
mesh_terms: D001938:Brazil; D005504:Food Analysis / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D059808:Polyphenols / Q000737:chemistry; D011429:Propolis / Q000737:chemistry*; D012621:Seasons; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D055549:Volatile Organic Compounds / Q000737:chemistry
chemical_list: D059808:Polyphenols; D055549:Volatile Organic Compounds; D011429:Propolis