title: Sensory classification of table olives using an electronic tongue: Analysis of aqueous pastes and brines.
abstract: Table olives are highly appreciated and consumed worldwide. Different aspects are used for trade category classification being the sensory assessment of negative defects present in the olives and brines one of the most important. The trade category quality classification must follow the International Olive Council directives, requiring the organoleptic assessment of defects by a trained sensory panel. However, the training process is a hard, complex and sometimes subjective task, being the low number of samples that can be evaluated per day a major drawback considering the real needs of the olive industry. In this context, the development of electronic tongues as taste sensors for defects' sensory evaluation is of utmost relevance. So, an electronic tongue was used for table olives classification according to the presence and intensity of negative defects. Linear discrimination models were established based on sub-sets of sensor signals selected by a simulated annealing algorithm. The predictive potential of the novel approach was first demonstrated for standard solutions of chemical compounds that mimic butyric, putrid and zapateria defects (≥93% for cross-validation procedures). Then its applicability was verified; using reference table olives/brine solutions samples identified with a single intense negative attribute, namely butyric, musty, putrid, zapateria or winey-vinegary defects (≥93% cross-validation procedures). Finally, the E-tongue coupled with the same chemometric approach was applied to classify table olive samples according to the trade commercial categories (extra, 1stchoice, 2ndchoice and unsuitable for consumption) and an additional quality category (extra free of defects), established based on sensory analysis data. Despite the heterogeneity of the samples studied and number of different sensory defects perceived, the predictive linear discriminant model established showed sensitivities greater than 86%. So, the overall performance achieved showed that the electrochemical device could be used as a taste sensor for table olives organoleptic trade successful classification, allowing a preliminary quality assessment, which could facilitate, in the future, the complex task of sensory panelists.
authors.affiliation: School of Agriculture, Polytechnic Institute of Bragança, Campus Santa Apolónia, 5300-253 Bragança, Portugal; Universidade Tecnológica Federal do Paraná-UTFPR, Avenida Brasil, Câmpus Medianeira, 4232-Parque Independência, Medianeira, Parana 85884-000, Brazil.
authors.forename: Ítala
authors.initials: Í
authors.lastname: Marx
authors.affiliation: REQUIMTE-LAQV/CIMO, School of Agriculture, Polytechnic Institute of Bragança, Campus Santa Apolónia, 5300-253 Bragança, Portugal; Universidad de Léon, Departamento de Ingeniería Agrária, Av. Portugal, no. 41, 24071 Léon, España.
authors.forename: Nuno
authors.initials: N
authors.lastname: Rodrigues
authors.affiliation: School of Agriculture, Polytechnic Institute of Bragança, Campus Santa Apolónia, 5300-253 Bragança, Portugal; CQ-VR, Centro de Química - Vila Real, University of Trás-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real, Portugal.
authors.forename: Luís G
authors.initials: LG
authors.lastname: Dias
authors.affiliation: Instituto Politécnico de Coimbra, ISEC, DEQB, Rua Pedro Nunes, Quinta da Nora, 3030-199 Coimbra, Portugal; CEB - Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
authors.forename: Ana C A
authors.initials: AC
authors.lastname: Veloso
authors.affiliation: REQUIMTE-LAQV, School of Agriculture, Polytechnic Institute of Bragança, Campus Santa Apolónia, 5300-253 Bragança, Portugal.
authors.forename: José A
authors.initials: JA
authors.lastname: Pereira
authors.affiliation: Universidade Tecnológica Federal do Paraná-UTFPR, Avenida Brasil, Câmpus Medianeira, 4232-Parque Independência, Medianeira, Parana 85884-000, Brazil.
authors.forename: Deisy A
authors.initials: DA
authors.lastname: Drunkler
authors.affiliation: Laboratory of Separation and Reaction Engineering - Laboratory of Catalysis and Materials (LSRE-LCM), Escola Superior Agrária, Instituto Politécnico de Bragança, Campus Santa Apolónia, 5300-253 Bragança, Portugal. Electronic address: peres@ipb.pt.
authors.forename: António M
authors.initials: AM
authors.lastname: Peres
mesh_terms: D020148:Butyric Acid / Q000032:analysis; D003509:Cyclohexanecarboxylic Acids / Q000032:analysis; D062609:Electronic Nose; D006801:Humans; D008623:Mercaptoethanol / Q000032:analysis; D031658:Olea / Q000737:chemistry* / Q000145:classification; D015203:Reproducibility of Results; D012492:Salts / Q000737:chemistry*; D013649:Taste; D055697:Taste Perception
chemical_list: D003509:Cyclohexanecarboxylic Acids; D012492:Salts; C017082:brine; D020148:Butyric Acid; D008623:Mercaptoethanol; C044895:cyclohexanecarboxylic acid
keywords: Electronic tongue; Linear discriminant analysis; Sensory defects; Simulated annealing algorithm; Table olives; Trade category classification