Varietal authentication of virgin olive oil: Proving the efficiency of sesquiterpene fingerprinting for Mediterranean Arbequina oils

Virgin olive oil (VOO) is a highly appreciated product fundamental in the Mediterranean diet. Since its sensory attributes are greatly influenced by the olive cultivar, the varietal authentication of VOOs is needed to protect consumers from misleading information. The present study aims to evaluate the suitability of sesquiterpene hydrocarbon (SH) fingerprint as VOO cultivar marker beyond geographical, agronomical and processing conditions. The study was mainly focused on Mediterranean Arbequina oils. SH profile of more than 400 VOOs from 6 counties and 38 different cultivars and coupages was analysed by Headspace Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS-SPME-GC-MS). Partial Least Square-Discriminant Analysis (PLS-DA) classification models were built with the aligned chromatograms. A binary PLS-DA model was built to distinguish 'Arbequina' oils from those of other cultivars (non-'Arbequina' class) and it was externally validated. The results of the external validation showed a 95.1% of overall correct classification confirming the suitability of SH fingerprint as a screening method for the authentication of Arbequina VOO. Also, the discrimination capacity of SH fingerprinting to authenticate VOOs from other cultivars was preliminary explored and promising results were obtained

Stepwise strategy based on 1H-NMR fingerprinting in combination with chemometrics to determine the content of vegetable oils in olive oil mixtures

1H NMR fingerprinting of edible oils and a set of multivariate classification and regression models organised in a decision tree is proposed as a stepwise strategy to assure the authenticity and traceability of olive oils and their declared blends with other vegetable oils (VOs). Oils of the 'virgin olive oil' and 'olive oil' categories and their mixtures with the most common VOs, i.e. sunflower, high oleic sunflower, hazelnut, avocado, soybean, corn, refined palm olein and desterolized high oleic sunflower oils, were studied. Partial least squares (PLS) discriminant analysis provided stable and robust binary classification models to identify the olive oil type and the VO in the blend. PLS regression afforded models with excellent precisions and acceptable accuracies to determine the percentage of VO in the mixture. The satisfactory performance of this approach, tested with blind samples, confirm its potential to support regulations and control bodies. Keywords: Adulteration; Authentication; Decision tree; Multivariate data analysis; Nuclear magnetic resonance; Olive oil

Short communication: Natural molecules for the control of Paenibacillus larvae, causal agent of American foulbrood in honey bees (Apis mellifera L.)

Aim of study: To evaluate the potential bactericidal activity of natural molecules against Paenibacillus larvae. Moreover, we investigated if molecules that exhibit antimicrobial activity were able to inhibit the proteolytic activity of the bacterium.Area of study: Isolates S1 and S2 were from Balcarce, Buenos Aires province, strain S3 from Rio Cuarto, Cordoba province, strain S4 from Concordia, Entre Rios province, strain S5 and S8 from Necochea, Buenos Aires, strain S6 and S7 from Mar del Plata, Buenos Aires, strain S9 from Modena, Italy and strain S10 from Emilia Reggio, Italy.Material and methods: Bacterial isolates identification was carried out by amplification of a specific 16S rRNA gene fragment of P. larvae using primers PL5 and PL4. Screening of the antimicrobial activity of thirteen molecules against four P. larvae isolates was conducted by the agar diffusion technique. The antimicrobial activity of selected molecules was evaluated by broth microdilution method.Main results: Menadione, lauric acid, monoglyceride of lauric acid and naringenin showed antimicrobial activity against ten P. larvae isolates. Menadione and lauric acid showed the strongest activities, with minimum inhibitory concentration mean values ranging 0.78-3.125 µg/mLand 25-50 µg/mL, respectively.Research highlights: Those concentrations are feasible to be applied at field level, and constitute promissory candidates to be evaluated using in vivo larval models

Mass spectrometry fingerprinting coupled to National Institute of Standards and Technology Mass Spectral search algorithm for pattern recognition

A new analytical strategy based on mass spectrometry fingerprinting combined with the NIST-MS search program for pattern recognition is evaluated and validated. A case study dealing with the tracing of the geographical origin of virgin olive oils (VOOs) proves the capabilities of mass spectrometry fingerprinting coupled with NIST-MS search program for classification. The volatile profiles of 220 VOOs from Liguria and other Mediterranean regions were analysed by secondary electrospray ionization-mass spectrometry (SESI-MS). MS spectra of VOOs were classified according to their origin by the freeware NIST-MS search v 2.0. The NIST classification results were compared to well-known pattern recognition techniques, such as linear discriminant analysis (LDA), partial least-squares discriminant analysis (PLS-DA), k-nearest neighbours (kNN), and counter-propagation artificial neural networks (CP-ANN). The NIST-MS search program predicted correctly 96% of the Ligurian VOOs and 92% of the non-Ligurian ones of an external independent data set; outperforming the traditional chemometric techniques (prediction abilities in the external validation achieved by kNN were 88% and 84% for the Ligurian and non-Ligurian categories respectively). This proves that the NIST-MS search software is a useful classification tool

Eur. food res. technol.

The target of this paper is the study of anthocyanin and tannin extraction from red grape during maceration, the formation of new pigments, and the evolution profiles of anthocyanin derivatives and tannins during the alcoholic and malolactic fermentations and aging in oak barrels and steel vats. 2 anthocyanins, 38 anthocyanin derivatives and 37 tannins were monitored. Formation of all classes of anthocyanin derivatives starts quickly after anthocyanin extraction from grape. Their maximum levels are reached a few days after apex of anthocyanins during maceration/alcoholic fermentation. Indirect condensation derivatives showed less stable behavior than that of the direct flavanol-anthocyanin products during fermentations and aging. Within pyranoanthocyanins, vitisin B had more instability than vitisin A. Extraction of tannins from grape occurs slower than that of anthocyanins. Major tannins are procyanidin homodimers with B bond (45% of total tannins after fermentations), followed by monomers (around 25%) and mixed B dimers (more than 10%). Tannins suffer a general continuous decrease during aging, with increasing relevance of more oxygenated tannins as aging advances. Fermentations are crucial stages in the formation of anthocyanin derivatives. In contrast, aging causes a continuous degradation for nearly all classes of anthocyanin derivatives and tannins, with a more stable behavior for some of them. Thus, establishing with confidence which enological conditions favor each type of derivative during fermentation is an important goal for future research. This work studies many individual compounds, involves exhaustive sampling and covers the different winemaking stages at an industrial winemaking scale, contributing to a more complete vision

Geographical authentication of virgin olive oil by GC-MS sesquiterpene hydrocarbon fingerprint: Verifying EU and single country label-declaration

According to the last report from the European Union (EU) Food Fraud Network, olive oil tops the list of the most notified products. Current EU regulation states geographical origin as mandatory for virgin olive oils, even though an official analytical method is still lacking. Verifying the compliance of label-declared EU oils should be addressed with the highest priority level. Hence, the present work tackles this issue by developing a classification model (PLS-DA) based on the sesquiterpene hydrocarbon fingerprint of 400 samples obtained by HS-SPME-GC-MS to discriminate between EU and non-EU olive oils, obtaining an 89.6% of correct classification for the external validation (three iterations), with a sensitivity of 0.81 and a specificity of 0.95. Subsequently, multi-class discrimination models for EU and non-EU countries were developed and externally validated (with three different validation sets) with successful results (average of 92.2% of correct classification for EU and 96.0% for non-EU countries). Keywords: Authenticity; Fingerprint; Geographical origin; PLS-DA; SPME-GC-MS; Sesquiterpene hydrocarbons; Virgin Olive Oil

1H-NMR and isotopic fingerprinting of olive oil and its unsaponifiable fraction: Geographical origin of virgin olive oils by pattern recognition

1H−NMR spectral data and H and C isotope abundances of virgin olive oils (VOOs) and their unsaponifiable fractions were analysed by pattern recognition techniques, such as principal component analysis (PCA) and partial−least squares discriminant analysis (PLS−DA). The aim was to develop chemical tools for the authentication of VOOs according to their geographical origin or Protected Designation of Origin (PDO), as well as to detect the mislabelling of the provenance of VOOs, at the regional or national level, or the mislabelling of non−PDO oils as PDO VOOs. The relationship between stable isotope abundances of the VOOs and their unsaponifiable fractions and the latitude of the VOO geographical origin was confirmed; but these criteria were not completely discriminant to differentiate VOOs according to their geographical origin. However, δ2H and/or δ13C data provided complementary geographical information to 1H−NMR data in the PLS−DA binary classification models afforded for VOOs from Greece, Spain, Italy, Izmir (Turkey), Crete (Greece), and the PDOs Riviera Ligure (Italy) and Huile d'olive d'Aix−en−Provence (France). 2H/1H and 13C/12C ratios of the unsaponifiable fractions of VOOs are reported here for the first time. The present approach for PDO Riviera Ligure VOOs, based on 1H−NMR data and C isotope abundance of the bulk oil and its unsaponifiable fraction, outperformed the previously reported classification models. Moreover, the PLS−DA models to authenticate VOOs from Greece and detect non−Greek VOOs achieved over 93 % of correct predictions.JRC.I.1-Chemical Assessment and Testin