Design and in-house validation of a portable system for the determination of free acidity in virgin olive oil. (October 2019)

• Record Type: Journal Article
• Authors: Grossi, Marco; Palagano, Rosa; Bendini, Alessandra; Riccò, Bruno; Servili, Maurizio; García-González, Diego Luis; Gallina Toschi, Tullia
• Is Part Of: Food control. Volume 104(2019)
• Page Start: 208
• Page End: 216
• Publication Date: 2019-10
• Subjects: Portable system -- Free acidity -- Virgin olive oil -- Impedance spectroscopy -- In-house validation -- Electrical conductance; EIS electrical impedance spectroscopy -- EVOO extra virgin olive oil -- FA free acidity -- LOD limit of detection -- LOO lampante olive oil -- LOQ limit of quantification -- RSD relative standard deviation -- TAGs triglycerides -- VOO virgin olive oil; Food -- Quality -- Periodicals; Food -- Analysis -- Periodicals; Food handling -- Periodicals; Food industry and trade -- Quality control -- Periodicals; Aliments -- Industrie et commerce -- Qualité -- Contrôle -- Périodiques; Aliments -- Qualité -- Périodiques; Aliments -- Analyse -- Périodiques; Hygiène alimentaire -- Périodiques; Food -- Analysis; Food handling; Food -- Quality; Periodicals; Electronic journals; 664.07
• DOI: 10.1016/j.foodcont.2019.04.019
• Languages: English
• ISSNs: 0956-7135

Abstract

Abstract: Nutritional and healthy values are well known properties of virgin olive oil (VOO). The product quality, in terms of belonging to a specific quality grade (extra virgin, virgin, lampante), is defined by a set of chemical-physical and sensory measurements. According to the official regulation of the European Union (EU Reg. 1348/2013) the free acidity is the first parameter that has to be determined by analysts; it gives information about the quality of the olives used to produce the VOO as well as the hydrolytic state of VOO just produced and stored. The official procedure is based on an acid-base titration that needs to be carried out in a chemical laboratory. In this paper a portable battery-operated electronic system to measure olive oil free acidity is presented: the system can be used for quick "in situ" tests in a production environment (olive oil mills or packaging centers) by people without particular training. The working principle of the system is based on the creation of an emulsion between oil and a hydroalcoholic solution: the free acidity is estimated on the value of the emulsion electrical conductance. The proposed system has been calibrated and in-house validated showing good results in terms of limit of detection and quantification, precision and accuracy. Moreover, a good correlation (R 2 adj = 0.97) with free acidity data obtained applying the official method on 30 olive oil samples belonging to different commercial categories (extra virgin, virgin and lampante olive oil) has been evidenced. Highlights: A portable system for the measurements of free acidity in olive oil has been built. The electrical conductance of an emulsion between a reagent and the oil is measured. The system showed good performances in the in-house validation. A good correlation with data measured applying the official method was evidenced.