2013, pp 589-653
Date: 05 Jul 2013

Olive Oil Authentication

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Abstract

This chapter describes the application of consumer methodologies to the study of extra virgin olive oil (EVOO). Due to the multivariate nature of consumer behavior, both qualitative and quantitative methods were employed to provide a more holistic view of the consumption behavior. A focus group technique showed that the diversity of the participants’ experiences with olive oil resulted in differences in existing perceptions regarding what constitutes an EVOO and the meaning of ‘extra virgin’ and determined how the combination of considered factors influenced purchase and usage motivations. A two-stage sorting task was conducted to identify American consumers’ opinions of 25 EVOOs based on visual assessments of the bottles. The majority of the consumers perceived the EVOO bottles similarly; however the two-state sorting task allowed consumers to provide additional criteria of their perception of the products. Means-end chain analysis on the interview data revealed common grounds for consumption and buying motivations with three different consumer segments. As part of the quantitative research methods, survey research was employed to identify consumer preferences and attitudes regarding EVOO. Univariate and multivariate approaches were employed to understand how hedonic scores are related to descriptive analysis measurements. Three segments were identified using cluster analysis; the three segments agreed in the rejection of bitterness and pungency. In general, the positive drivers of liking are nutty, tea, green fruit, and green tomato. Some consumers are less sensitive to the presence of defects in EVOO and tend to like defective oils.

Before describing analytical solutions, this chapter first provides definitions of authenticity and describes the official methods supported by the European Communities, International Olive Council, and Codex Alimentarius.

The description of the current instrumental techniques has been split into two groups: (1) those based on contributions from almost all possible analytes (e.g., spectroscopy) and (2) those that rely on the measurement of more definite information obtained from fractionation of olive oil components (e.g., chromatography). In the first group, the chapter describes new applications of Fourier transform-Raman, Fourier transform-mid-infrared, fluorescence, and nuclear magnetic resonance (NMR), in addition to the traditional application of near-infrared (NIR) spectroscopy for determining trans fatty acids (FAs). The description of chromatographic techniques (high-performance liquid chromatography and HRGC), which are probably the most effective analytical approaches when the separation of olive oil components is required for authentication, includes a discussion about the methods for the individual quantification of FA methyl esters, triacylglycerols, diacylglycerols, FA alkyl esters, sterols, hydrocarbons, triterpene dialcohols and alcohols, aliphatic alcohols, waxes, and phenolic compounds. The chapter also analyzes new frontiers of research in the field of olive oil authenticity by means of the implementation of rapid methodologies or the identification and quantification of hitherto undetectable compounds with the help of sophisticated in-tandem techniques that have been developed recently. The next section, however, describes current problems with the official methods despite the arsenal of analytical techniques available at the moment.

Because analytical results are not exempt from errors, validated analytical methods are essential for the quality performance of analytical laboratories. Thus, the chapter has a special section devoted to method validation (Cochran and Grubbs tests, precision, repeatability, and reproducibility limits), the definition of validation characteristics (selectivity, sensitivity, robustness, linearity, LOD, LOQ), the use in practice of accuracy values by means of procedures for comparisons between laboratories, the measurement of uncertainty, and general requirements for the competence of laboratories to carry out analytical tests, calibrations, and sampling. The entire section is based on ISO standards.

The last section of the chapter, which is focused on future trends and perspectives, analyzes the global meaning of authenticity, genuine olive oils with a chemical composition that does not conform to international standards, and that the new trade standards prevent a casual relation between chemical compounds and authenticity can be interpreted as causal.