Instrumental and multivariate statistical analyses for the characterisation of the geographical origin of Apulian virgin olive oils

The verification of the geographical origin of olive oils by analytical techniques is still a challenge. The goal of this work is to explore the application and accuracy of different chemometric tools combined with near infrared spectroscopy (NIR) based analytical methods in the field of geographical authenticity of olive oils. As olive oils associated with different geographical origins are mainly characterized by different fatty acid (FA) and triacylglycerol (TAG) compositions, NIR methods for the fast and reliable determination of these parameters are developed. Next, these NIR methods are used to characterize a comprehensive set of olive oils (n > 5000) derived from 19 different countries. This set of data is used to build a statistical workflow, which allows the determination of the geographical origin of unknown olive oil samples. First of all, the untreated data set is pretreated by k‐means clustering and the selection of the relevant analytical variables by principal component analysis (PCA) and linear discriminant analysis (LDA) and min/max normalization of all parameters. Subsequently, classification is performed with a reduced sample set of the 200 most similar samples identified by k‐nearest neighbor tool (kNN). For classification purpose kNN, LDA, naïve Bayes classifier, and logit regression are applied. Practical Applications: The established statistical workflow can be used to verify the geographical origin of olive oils. The application and usage of up to four different statistical models for classification purpose results in a superior probability of the predicted origin in comparison to the application of only one single statistical classification test. As standardized methods are used as reference methods for building the NIR methods, the FA and TAG composition and the iodine value can be either determined by the standard methods or by the described NIR method. The presented statistical approach will help to build up a system for the verification of the geographical origin of olive oils.

Section: Introductionmentioning

confidence: 99%

A Systematic Chemometric Approach to Identify the Geographical Origin of Olive Oils

Gertz¹,

Gertz²,

Matthäus

et al. 2019

“…Olive oil from Istria is already known for its high nutritional quality, in particular due to high content of oleic acid . Nevertheless, for routine olive oil geographical characterization, standard analytical methods are still laborious and time‐consuming while this issue is a raising concern both among consumers and authorities . Indeed, the origin of food has important consequences on the final food product quality.…”

Section: Introductionmentioning

confidence: 99%

MALDI‐SpiralTOF technology for assessment of triacylglycerols in Croatian olive oils

Peršurić¹,

Osuga

Grbac

et al. 2016

Traceability and authenticity of olive oils in Croatia were probed by a versatile analytical approach using spiral MALDI-TOF MS system for the triacylglycerol (TAG) analysis. Molecular ion patterns were shown to represent specific data for statistical analysis, in which differences of cultivar regions of Croatian coast were recognized. This pilot project allows indications to be followed in high throughput procedures with high number of samples to get statistically relevant data for discrimination of olive oils from different geographic sites. Additionally, the fragmentation in the TOF/TOF MS provided distinct highly valuable data for assignment of acyl residues. In this way molecular species with different fatty acid substituents can be clearly assigned and possible isomeric mixtures identified. Practical applications:Olive oil TAG analysis is important to determine authenticity of olive oil and detect adulteration. This work shows that spiral MALDI-TOF MS analysis of TAG composition is a promising method for tracing geographical differences in olive oils.

“…Indeed, over the last years, the chemical composition of olive oil has been widely used to identify its geographical origin, fact which is actually not surprising, since many authors have demonstrated that the olive oil composition is widely affected by the pedoclimatic conditions of the geographical area in which was produced . Certainly, characterizing major and minor components of olive oil for geographical classification purposes has been satisfactorily carried out on samples coming from diverse olive oil producing countries, mainly Spain , Italy , Greece , Tunisia , etc. In all the mentioned studies, different approaches combining profiling or fingerprinting of olive oil samples with the appropriate chemometric tools have been tested for the geographical classification of the studied oils, as well as the identification of markers that could facilitate this discrimination.…”

Section: Introductionmentioning

confidence: 99%

A first approach towards the development of geographical origin tracing models for North Moroccan olive oils based on triacylglycerols profiles

Bajoub

Medina‐Rodríguez

Hurtado‐Fernández

et al. 2015

The triacylglycerols composition of monovarietal Picholine Marocaine olive oils, produced in seven of the most productive areas in northern Morocco, has been established for the first time, starting a register of typicality and geographical identity of Moroccan olive oils. Two hundred seventy-nine olive samples were collected over two consecutive crop seasons (2011/2012 (n ¼ 140) and 2012/2013 (n ¼ 139)), the analysis of the triacylglycerol profiles of the obtained oils was performed using high performance liquid chromatography, the influence of the region of provenance was investigated, and chemometric data analysis (including principal components analysis, linear discriminant analysis, partial least squares-discriminant analysis, and soft independent modeling of class analogies) was used to differentiate the studied samples according to their geographical origin. Twenty-one triacylglycerols were characterized and the variability observed among the studied samples could be related to the production area. The combination of triacylglycerols composition with chemometrics provided a powerful tool to verify the geographical origin of north Moroccan olive oils.Practical applications: Moroccan legislations established Geographic Indication labels for adding value to typical products. However, the general procedure to control the geographical authenticity of these protected products remains based on the traceability of their production and there is a lack of appropriate and reliable tools for their geographical unambiguous authentication and control. In this work, geographical authentication models for classifying olive oil samples (based on triacylglycerols composition) have been developed and evaluated, achieving adequate classification and prediction rates for oils coming from the main north Moroccan olive growing areas. The results obtained herein, could represent a significant contribution to the control of the geographical authenticity of Moroccan olive oils.