title: Thermal and chemical evaluation of naturally auto-oxidised virgin olive oils: a correlation study.
abstract: BACKGROUND
  The nature of the relationship between differential scanning calorimetry thermal properties and the oxidation and hydrolysis compounds formed during a real auto-oxidation process in virgin olive oils has not been evaluated so far, as these samples are difficult to find. In this work, 21 samples of virgin olive oil, stored under ideal conditions since their years of production (production range 1991-2005) to develop the natural auto-oxidation process, were analysed in order to evaluate this relationship.
  
  
  RESULTS
  Oils stored the longest time showed the highest hydrolytic degradation while the others exhibited higher contents of oxidised fatty acids and triacylglycerols, instead. Thermal properties of transitions were differently influenced by degradation compounds with the onset of both the cooling and heating profiles particularly influenced by diacylglycerols and oxidised lipids. Chemical data and thermal properties were correlated by using principal component analysis. Twenty-three variables were selected for the analysis with the first component fully segregating samples into two groups according to the year of storage and the level of hydrolysis and/or oxidation, on the basis of selected thermal properties obtained by cooling and heating transitions.
  
  
  CONCLUSIONS
  These preliminary findings showed that differential scanning calorimetry could be considered an useful tool to evaluate lipid degradation in virgin olive oils, indicating its value as a support to chemical techniques.
authors.affiliation: Dipartimento di Scienze degli Alimenti, Università degli Studi di Parma, Parco Area delle Scienze 95/A, I-43124 Parma, Italy. emma.chiavaro@unipr.it
authors.forename: Emma
authors.initials: E
authors.lastname: Chiavaro
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Cerretani
authors.forename: Vito Michele
authors.initials: VM
authors.lastname: Paradiso
authors.forename: Carmine
authors.initials: C
authors.lastname: Summo
authors.forename: Maria
authors.initials: M
authors.lastname: Paciulli
authors.forename: Tullia
authors.initials: T
authors.lastname: Gallina Toschi
authors.forename: Francesco
authors.initials: F
authors.lastname: Caponio
mesh_terms: D002152:Calorimetry, Differential Scanning; D003080:Cold Temperature / Q000009:adverse effects; D004042:Dietary Fats, Unsaturated / Q000032:analysis*; D004075:Diglycerides / Q000032:analysis / Q000737:chemistry; D005230:Fatty Acids, Nonesterified / Q000032:analysis / Q000737:chemistry; D005231:Fatty Acids, Unsaturated / Q000032:analysis / Q000737:chemistry; D005504:Food Analysis / Q000379:methods*; D063427:Food Quality; D061353:Food Storage; D005638:Fruit / Q000737:chemistry*; D006358:Hot Temperature / Q000009:adverse effects; D006868:Hydrolysis; D007558:Italy; D031658:Olea / Q000737:chemistry*; D000069463:Olive Oil; D010084:Oxidation-Reduction; D010938:Plant Oils / Q000737:chemistry* / Q000592:standards; D025341:Principal Component Analysis; D013045:Species Specificity; D014280:Triglycerides / Q000032:analysis / Q000737:chemistry
chemical_list: D004042:Dietary Fats, Unsaturated; D004075:Diglycerides; D005230:Fatty Acids, Nonesterified; D005231:Fatty Acids, Unsaturated; D000069463:Olive Oil; D010938:Plant Oils; D014280:Triglycerides
keywords: DSC; HPSEC; auto-oxidation; virgin olive oil