Supporting the Sensory Panel to Grade Virgin Olive Oils: An In-House-Validated Screening Tool by Volatile Fingerprinting and Chemometrics

Abstract

The commercial category of virgin olive oil is currently assigned on the basis of chemical-physical and sensory parameters following official methods. Considering the limited number of samples that can be analysed daily by a sensory panel, an instrumental screening tool could be supportive by reducing the assessors’ workload and improving their performance. The present work aims to in-house validate a screening strategy consisting of two sequential binary partial least squares-discriminant analysis (PLS-DA) models that was suggested to be successful in a proof-of-concept study. This approach is based on the volatile fraction fingerprint obtained by HS-SPME–GC–MS from more than 300 virgin olive oils from two crop seasons graded by six different sensory panels into extra virgin, virgin or lampante categories. Uncertainty ranges were set for the binary classification models according to sensitivity and specificity by means of receiver operating characteristics (ROC) curves, aiming to identify boundary samples. Thereby, performing the screening approach, only the virgin olive oils classified as uncertain (23.3%) would be assessed by a sensory panel, while the rest would be directly classified into a given commercial category (78.9% of correct classification). The sensory panel’s workload would be reduced to less than one-third of the samples. A highly reliable classification of samples would be achieved (84.0%) by combining the proposed screening tool with the reference method (panel test) for the assessment of uncertain samples.

Chromatographic Fingerprinting Strategy to Delineate Chemical Patterns Correlated to Coffee Odor and Taste Attributes

“…Several analytical approaches and/or integrated strategies have been attempted over the years to combine the chemical composition of a product with its flavor profile; − however, to date, they have not replaced the sensory panel evaluation, especially in regulatory contexts where sensory quality defines labeling (e.g., extra-virgin olive oil , ) or a commercial value (e.g., coffee ,,,,,− ).…”

Chromatographic Fingerprinting Enables Effective Discrimination and Identitation of High-Quality Italian Extra-Virgin Olive Oils

“…Odor-active compounds, with a low odor perception threshold, and volatiles lacking sensory features (i.e., interferents), 33 concur in the modulation of the “odor code” while triggering aroma perception, whose objectification by instrumental methods is challenging. 9 , 34 However, EVOO volatiles encrypt additional information about relevant functional variables including olive cultivars, the olive tree’s harvest region and local pedoclimatic conditions, olive ripeness, technological processes, and storage condition. 1 , 2 , 35 , 36 …”

“…Odor-active compounds, with a low odor perception threshold, and volatiles lacking sensory features (i.e., interferents), 33 concur in the modulation of the "odor code" while triggering aroma perception, whose objectification by instrumental methods is challenging. 9,34 However, EVOO volatiles encrypt additional information about relevant functional variables including olive cultivars, the olive tree's harvest region and local pedoclimatic conditions, olive ripeness, technological processes, and storage condition. 1,2,35,36 Figure 1A shows the pseudocolor image of a Sicilian EVOO (Sicilia origin#S1) volatile fraction comprehensively mapped through untargeted and targeted (UT) peak regions (red graphics); identified/targeted analytes (i.e., targeted compounds) are highlighted by green circles.…”

“…Moreover, using volatile fingerprinting based on 1D-GC, it was also possible to support the commercial classification of OO based on sensory panel evaluation. 9 EVOOs are in fact characterized by peculiar yet essential aroma qualities such as green, grassy, and fruity notes, whose perception is at the basis of commercial classification based on EU regulations. Sensory quality in fact, together with compositional/chemical standards to be complied, 5 and absence of off-flavors guide the OO classification in EVOO (median of the defects = 0.0 and median of the positive attribute > 0.0), virgin olive oil (VOO—median of the defects between 0.0 and 3.5 and median of the positive attribute > 0.0), and lampante olive oil (LOO—median of the defects > 6.0) in the presence of sensory defects (rancid, fusty/muddy, musty, and winey/vinegary), even at lower levels (e.g., median of the defects ≠ 0).…”

E-Nose and Olfactory Assessment: Teamwork or a Challenge to the Last Data? The Case of Virgin Olive Oil Stability and Shelf Life

“…Analytical approaches, mainly represented by chromatographic (high-performance liquid chromatography, gas chromatography-mass spectrometry, gas chromatography-ion mobility spectrometry), vibrational (FTIR, MIR, NIR and Raman spectroscopy), spectroscopic (ultraviolet-visible, nuclear magnetic resonance, mass spectroscopy, fluorescence spectroscopy, CO 2 laser infrared optothermal spectroscopy, dielectric spectroscopy, visible spectroscopy, ultraviolet-ion mobility spectrometry) and thermal techniques (differential scanning calorimetry, thermogravimetric analyzer), provide a more precise indication of olive oil composition [8,9]. However, even in these cases some important limitations are present: these techniques require expensive and bulky instruments, high-purity gas carriers, complex and often long sample preparation and, lastly, trained personnel, therefore limiting their use only to qualified laboratories.…”