Browsing by Author "Silva, Lucas M."
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Classification of olive oils according to sensory defects using a potentiometric electronic tonguePublication . Silva, Lucas M.; Dias, L.G.; Rodrigues, Nuno; Veloso, Ana C.A.; Rebello, Ligia P.G.; Pereira, J.A.; Peres, António M.Olive oil is a highly appreciated food product being very prone to frauds. Olive oils may be graded as extra-virgin, virgin or lampante. This classification is attributed according to legal requirements, including chemical parameters and sensorial analysis. Among the organoleptic sensations, the capability of perceiving the presence or absence of sensory defects plays a key role for olive oils grade classification. This task is time-consuming and quite expensive, requiring the use of an official taste panel, which can only evaluate a low number of samples per day. In this work, an electronic tongue is proposed to discriminate olive oils according to the defect predominantly perceived (winey-vinegary, wet-wood, rancid and fusty/muddy sediment), by a trained sensory panel. Sub-sets of potentiometric signal profiles obtained from the lipid sensor membranes of the taste electrochemical device were selected using a simulated annealing meta-heuristic algorithm, allowing establishing classification linear discriminant model, which showed a predictive success classification rate of 81% for leave-one-out or cross-validation procedure. The satisfactory predictive performance achieved pointed out the practical potential of using this artificial taste sensor as a complementary methodology for olive oil sensory analysis.
- Classification of olive oils according to sensory defects using a potentiometric electronic tonguePublication . Silva, Lucas M.; Dias, L.G.; Rodrigues, Nuno; Veloso, Ana C.A.; Rebello, Ligia P.G.; Pereira, J.A.; Peres, António M.Olive oil is a highly appreciated food product being very prone to frauds. Olive oils may be graded as extra-virgin, virgin or lampante. This classification is attributed according to legal requirements, including chemical parameters and sensorial analysis. Among the organoleptic sensations, the capability of perceiving the presence or absence of sensory defects plays a key role for olive oils grade classification. This task is time-consuming and quite expensive, requiring the use of an official taste panel, which can only evaluate a low number of samples per day. In this work, an electronic tongue is proposed to discriminate olive oils according to the defect predominantly perceived (winey-vinegary, wet-wood, rancid and fusty/muddy sediment), by a trained sensory panel. Sub-sets of potentiometric signal profiles obtained from the lipid sensor membranes of the taste electrochemical device were selected using a simulated annealing meta-heuristic algorithm, allowing establishing classification linear discriminant model, which showed a predictive success classification rate of 81% for leave-one-out or cross-validation procedure. The satisfactory predictive performance achieved pointed out the practical potential of using this artificial taste sensor as a complementary methodology for olive oil sensory analysis.
- Classification of olive oils according to sensory defects using a potentiometric electronic tonguePublication . Silva, Lucas M.; Dias, L.G.; Rodrigues, Nuno; Veloso, Ana C.A.; Rebello, Ligia P.G.; Pereira, J.A.; Peres, António M.Olive oils may be graded according to their overall physicochemical composition and sensorial attributes as: -extra-virgin olive oils (EVOOs); -virgin olive oils (VOOs); - lampante olive oils (LOOs). Olive oils are quite prone to frauds thus there are legal protection EU Commission regulations: - EU Commission Regulation, 1991; - EU Commission Regulation, 2011. Maximum levels are established for: - Chemical and physicochemical parameters (e.g., free acidity, peroxide value, UV extinction coefficients and alkyl esters content)i -Sensory attributes (presence/absence of organoleptic defects, fruity sensation and positive attribute).
- Perception of olive oils sensory defects using a potentiometric taste devicePublication . Veloso, Ana C.A.; Silva, Lucas M.; Rodrigues, Nuno; Rebello, Ligia P.G.; Dias, L.G.; Pereira, J.A.; Peres, António M.The capability of perceiving olive oils sensory defects and intensities plays a key role on olive oils quality grade classification since olive oils can only be classified as extra-virgin if no defect can be perceived by a human trained sensory panel. Otherwise, olive oils may be classified as virgin or lampante depending on the median intensity of the defect predominantly perceived and on the physicochemical levels. However, sensory analysis is time-consuming and requires an official sensory panel, which can only evaluate a low number of samples per day. In this work, the potential use of an electronic tongue as a taste sensor device to identify the defect predominantly perceived in olive oils was evaluated. The potentiometric profiles recorded showed that intra- and inter-day signal drifts could be neglected (i.e., relative standard deviations lower than 25%), being not statistically significant the effect of the analysis day on the overall recorded E-tongue sensor fingerprints (P-value = 0.5715, for multivariate analysis of variance using Pillai's trace test), which significantly differ according to the olive oils’ sensory defect (P-value = 0.0084, for multivariate analysis of variance using Pillai's trace test). Thus, a linear discriminant model based on 19 potentiometric signal sensors, selected by the simulated annealing algorithm, could be established to correctly predict the olive oil main sensory defect (fusty, rancid, wet-wood or winey-vinegary) with average sensitivity of 75±3% and specificity of 73±4% (repeated K-fold cross-validation variant: 4 folds×10 repeats). Similarly, a linear discriminant model, based on 24 selected sensors, correctly classified 92±3% of the olive oils as virgin or lampante, being an average specificity of 93±3% achieved. The overall satisfactory predictive performances strengthen the feasibility of the developed taste sensor device as a complementary methodology for olive oils’ defects analysis and subsequent quality grade classification. Furthermore, the capability of identifying the type of sensory defect of an olive oil may allow establishing helpful insights regarding bad practices of olives or olive oils production, harvesting, transport and storage.