Monitoring oxidation changes in commercial extra virgin olive oils with fluorescence spectroscopy-based prototype

Abstract

Maintaining the quality of extra virgin olive oils (EVOOs) in the current globalised market is a key challenge for the olive oil manufacturers. To maintain the quality, one major factor is to resist its oxidation during processing and storage. Resisting the oxidation in EVOOs is a challenging task requiring control of different physical and chemical factors. However, rapid, real-time, and non-destructive monitoring the oxidation in EVOOs could support in maintaining its quality during storage. The present study utilises a novel right-angle fluorescence spectroscopy-based prototype for rapid monitoring of oxidation changes in three different EVOOs varieties (Arbequina, Picual, and Cornicabra) during storage. Furthermore, the effects of light exposure on oxidation of EVOOs were also studied. Two major changes in the fluorescence spectra of EVOO samples were mainly observed: a decrease in fluorescence emission intensity at 671 nm, and an increase in fluorescence intensities at 420, 440, 464, and 515 nm. These two changes were related to a decrease in chlorophyll content and parallel formation of oxidation products. The formation of oxidation products was found to have a linear relationship with the decrease in chlorophyll content. Out of the three, the Cornicabra variety showed the highest rate of oxidation changes. Furthermore, the EVOOs degraded rapidly when get exposed to light. In a fast and non-destructive manner, the fluorescence spectroscopy-based prototype successfully monitored the oxidation changes in the EVOOs. Keywords Extra virgin olive oil • Oxidation • Storage • Light exposure Abbreviations C0 2) Singlet oxygen (3 0 2) Triplet oxygen EU European Union EVOOs Extra virgin olive oils nm Nanometre UV-Vis Ultraviolet and visible VOOs Virgin olive oils Compliance with ethical standards Conflict of interest The authors declare no conflict of interest. Compliance with ethics requirements This article does not contain any studies with human and animal subjects.

Development of Rapid Extra Virgin Olive Oil Quality Assessment Procedures Based on Spectroscopic Techniques

“…The emission spectra were acquired from 350-700 nm [12]. Such spectra presented similar patterns as those showed by previous works [10,11]. Chlorophyll produced a dominant peak at 670 nm that decreased with the adulteration level.…”

“…The major interest in polyphenols and tocopherols arises from their antioxidant activity. Previous studies on fluorescence spectra of olive oil [5][6][7][8][9][10][11][12] revealed the characteristic spectral patterns of different oil qualities according to the presence of peaks at certain wavelengths and to their signal intensity. Such patterns allowed the development of multivariate models for discrimination between categories [9][10][11].…”

Tracking Sensory Characteristics of Virgin Olive Oils During Storage: Interpretation of Their Changes from a Multiparametric Perspective

“…In the last decade, numerous authors have focused on tracking different compounds and parameters of VOO during its shelf life. The majority of these studies have aimed to monitor the changes in the quality parameters of VOO during the storage under different conditions and with different types of containers [5,21]. Other authors have centered their studies on the loss of VOO healthy compounds, such as phenols, during the shelf life under different storage conditions [22][23][24].…”

Physical and chemical behaviour of Nabali Mohassan single‐cultivar olive oil during prolonged storage

“…Olive oil shows that several fluorophores, such as tocopherols and tocotrienols, chlorophylls and phenolic compounds, are all subjected to variation during oil storage, thus suggesting that fluorescence spectroscopy can be applied to obtain information about oil aging. Several studies recently showed that fluorescence spectroscopy can be effectively used to measure the photo‐ and thermal degradation of olive oil when aiming to assess its quality and freshness . This technique has also been the object of recent evolutions, such as the application of an optical fibre smartphone spectrofluorimeter, based on the ‘lab‐in‐a‐phone’ approach …”

“…Several studies recently showed that fluorescence spectroscopy can be effectively used to measure the photo-and thermal degradation of olive oil when aiming to assess its quality and freshness. 10,[14][15][16][17][18] This technique has also been the object of recent evolutions, such as the application of an optical fibre smartphone spectrofluorimeter, based on the 'lab-in-a-phone' approach. 18 The physical properties of virgin olive oil, such as refractive index, mass density and viscosity, are also important for quality.…”