A taste sensor device for unmasking admixing of rancid or winey-vinegary olive oil to extra virgin olive oil

Abstract

A B S T R A C TElectrochemical sensor devices have gathered great attention in food analysis namely for olive oil evaluation. The adulteration of extra-virgin olive oil with lower-grade olive oil is a common worldwide fraudulent practice, which detection is a challenging task. The potentiometric fingerprints recorded by lipid polymeric sensor membranes of an electronic tongue, together with linear discriminant analysis and simulated annealing metaheuristic algorithm, enabled the detection of extra-virgin olive oil adulterated with olive oil for which an intense sensory defect could be perceived, specifically rancid or winey-vinegary negative sensations. The homemade designed taste device allowed the identification of admixing of extra-virgin olive oil with more than 2.5% or 5% of rancid or winey-vinegary olive oil, respectively. Predictive mean sensitivities of 84 ± 4% or 92 ± 4% and specificities of 79 ± 6% or 93 ± 3% were obtained for rancid or winey-vinegary adulterations, respectively, regarding an internal-validation procedure based on a repeated K-fold cross-validation variant (4 folds × 10 repeats, ensuring that the dataset was forty times randomly split into 4 folds, leaving 25% of the data for validation purposes). This performance was satisfactory since, according to the legal physicochemical and sensory analysis, the intentionally adulterated olive oil with percentages of 2.5-10%, could still be commercialized as virgin olive oil. It could also be concluded that at a 5% significance level, the trained panelists could not distinguish extra-virgin olive oil samples from those adulterated with 2.5% of rancid olive oil or up to 5% of winey-vinegary olive oil. Thus, the electronic tongue proposed in this study can be foreseen as a practical and powerful tool to detect this kind of worldwide common fraudulent practice of high quality olive oil.

Olive Oil Quality and Sensory Changes During House‐Use Simulation and Temporal Assessment Using an Electronic Tongue

“…Nevertheless, it should be noticed that, from a quality point of view, the observed variation ( Fig. The overall satisfactory classification performance of the E-tongue-LDA-SA approach is in accordance with previous studies that demonstrated the capability of this type of taste sensor device for olive oil analysis, including the assessment of levels of physicochemical quality parameters during 1 year of distribution storage as well as the evaluation of the intensities of positive-or negative-sensory attributes of (Harzalli et al, 2018;Veloso et al, 2016Veloso et al, , 2018. In contrast, PV were significantly affected by the storage time period whose levels increased with the storage time period and no significant effect was found due to the manner the bottles were conditioned after each simulated domestic use (i.e., closed or left open).…”

“…The lab-made potentiometric E-tongue multisensor device comprised two print-screen sensor arrays, each containing 20 lipid polymeric sensor membranes (40 sensors in total), as previously described by Veloso et al (2018) and Harzalli et al (2018). The sensor membranes were a mixture of one lipid additive (~3%: octadecylamine, oleyl alcohol, methyltrioctylammonium chloride, or oleic acid), one plasticizer (~32%: bis(1-butylpentyl) adipate, dibutyl sebacate, 2-nitrophenyl-octylether, tris(2-ethylhexyl)phosphate, or dioctyl phenylphosphonate), and polyvinyl chloride (PVC, 65%) (Fluka, Madrid, Spain; minimum purity ≥97%).…”

“…During this process, the olive oil is shaken due to the bottle manipulation, promoting the introduction of atmospheric oxygen into the bottle headspace at every use (Di Lecce et al, 2006;Genovese et al, 2015). It aimed to qualitatively and/or quantitatively assess the physicochemical quality parameters, oxidative stability (OS), and positiveand negative-sensory attributes of olive oils, and, in some cases, to evaluate the effects of storage time and lighting conditions during the olive oil distribution and commercialization (i.e., unopened bottles) (Harzalli et al, 2018;Rodrigues et al, 2016;Veloso et al, 2018). Therefore, it would be helpful if it was possible to establish the shelf life of olive oil after its initial domestic use, i.e., during which time period the olive oil keeps its initial quality (EVOO and/or virgin olive oil, VOO) after the bottle is opened for the first time.…”

“…The use of potentiometric multisensor devices coupled with chemometric tools was previously reported. It aimed to qualitatively and/or quantitatively assess the physicochemical quality parameters, oxidative stability (OS), and positiveand negative-sensory attributes of olive oils, and, in some cases, to evaluate the effects of storage time and lighting conditions during the olive oil distribution and commercialization (i.e., unopened bottles) (Harzalli et al, 2018;Rodrigues et al, 2016;Veloso et al, 2018).…”

Olive Oil Total Phenolic Contents and Sensory Sensations Trends during Oven and Microwave Heating Processes and Their Discrimination Using an Electronic Tongue

“…The 40 sensors included in the device corresponded to different mixtures of 4 additives (octadecylamine, oleyl alcohol, methyltrioctylammonium chloride, and oleic acid; ∼3%) and 5 plasticizers (bis(1-butylpentyl) adipate, dibutyl sebacate, 2-nitrophenyloctylether, tris(2-ethylhexyl)phosphate, and dioctyl phenylphosphonate; ∼65%), plus high molecular weight polyvinyl chloride (PVC; ∼32%) [20]. The lipid polymeric membranes were used since they show qualitative and quantitative potentiometric signal responses towards solutions mimicking positive attributes (e.g., bitter, fruity, green, and pungent sensations) and negative attributes (rancid, winey-vinegary, fusty, and musty defects) usually perceived in olive oils [24][25][26]34] and basic taste sensations (bitter, sweet, acid, salty, and umami) [38,39]. Indeed, the lipid polymeric sensor membranes contain hydrophobic and hydrophilic groups that interact with taste substances via electrostatic or hydrophobic interactions [40].…”