Rapid direct analysis to discriminate geographic origin of extra virgin olive oils by flash gas chromatography electronic nose and chemometrics

At present, the geographical origin of extra virgin olive oils can be ensured by documented traceability, although chemical analysis may add information that is useful for possible confirmation. This preliminary study investigated the effectiveness of flash gas chromatography electronic nose and multivariate data analysis to perform rapid screening of commercial extra virgin olive oils characterized by a different geographical origin declared in the label. A comparison with solid phase micro extraction coupled to gas chromatography mass spectrometry was also performed. The new method is suitable to verify the geographic origin of extra virgin olive oils based on principal components analysis and discriminant analysis applied to the volatile profile of the headspace as a fingerprint. The selected variables were suitable in discriminating between '100% Italian' and 'non-100% Italian' oils. Partial least squares discriminant analysis also allowed prediction of the degree of membership of unknown samples to the classes examined

Application of solid phase microextraction to evaluate traces of thymol in honey

The solid phase microextraction technique was tested for thymol evaluation in honey. Thymol can be present in honey as a residue of treatments against Varroa destructor Honey was sampled from apiaries treated with anti-Varroa products whose active ingredient is thymol. Thymol evaluation was done using the internal standard method; benzophenone and carvacrol were tested as internal standards/ the best results were obtained using benzophenone. The application of an alkaline hydrolysis was important for obtaining quantitative recoveries

Optimised off-line SPE-GC-FID method for the determination of mineral oil saturated hydrocarbons (MOSH) in vegetable oils

4siAn optimised off-line SPE–GC–FID method based on the use of silver-silica gel was developed for the determination of mineral oil saturated hydrocarbons (MOSH) in vegetable oils, including olive pomace oil. The method is specific in not including the aromatic hydrocarbons. The performance of different silica gels (untreated, activated and treated with silver nitrate) was compared in terms of capacity to retain fat and retention of interfering olefins present in particularly large amounts in refined olive oils. A coefficient of variation of 9% was obtained performing six replicate analyses of an extra virgin olive oil fortified with an amount of MOSH near the estimated LOQ (15 mg/kg). Recoveries were close to 100%. The use of activated aluminium oxide as an additional tool to eliminate interference by endogenous long-chain n-alkanes, is discussed.reservedmixedMoret, Sabrina; Barp, Laura; Grob, Konrad; Conte, LanfrancoMoret, Sabrina; Barp, Laura; Grob, Konrad; Conte, Lanfranc

Evaluation of Some Fixed Components for Unifloral Honey Characterization

The classification of honeys according to their botanical origin is a problem usually solved by means of microscopic observation of pollens and by evaluation of organoleptic characteristics such as color, taste, and others. In this paper, a number of chemical parameters including water activity, free amino acid composition, reducing sugars, total sugars, and pH were evaluated for a number of samples of some different botanical origin honeys. The results were evaluated by chemometric methods, and this allowed discrimination between the different origins, also for some critical cases such as chestnut and lime tre

Toward a definition of blueprint of virgin olive oil by comprehensive two-dimensional gas chromatography

This study investigates the applicability of an iterative approach aimed at defining a chemical blueprint of virgin olive oil volatiles to be correlated to the product sensory quality. The investigation strategy proposed allows to fully exploit the informative content of a comprehensive multidimensional gas chromatography (GC 7 GC) coupled to a mass spectrometry (MS) data set. Olive oil samples (19), including 5 reference standards, obtained from the International Olive Oil Council, and commercial samples, were submitted to a sensory evaluation by a Panel test, before being analyzed in two laboratories using different instrumentation, column set, and software elaboration packages in view of a cross-validation of the entire methodology. A first classification of samples based on untargeted peak features information, was obtained on raw data from two different column combinations (apolar 7 polar and polar 7 apolar) by applying unsupervised multivariate analysis (i.e., principal component analysis\u2014PCA). However, to improve effectiveness and specificity of this classification, peak features were reliably identified (261 compounds), on the basis of the MS spectrum and linear retention index matching, and subjected to successive pair-wise comparisons based on 2D patterns, which revealed peculiar distribution of chemicals correlated with samples sensory classification. The most informative compounds were thus identified and collected in a \u201cblueprint\u201d of specific defects (or combination of defects) successively adopted to discriminate Extra Virgin from defected oils (i.e., lampante oil) with the aid of a supervised approach, i.e., partial least squares-discriminant analysis (PLS-DA). In this last step, the principles of sensomics, which assigns higher information potential to analytes with lower odor threshold proved to be successful, and a much more powerful discrimination of samples was obtained in view of a sensory quality assessment