Extra Virgin Olive Oil Quality Research Articles

Applying Spectroscopies, Imaging Analyses, and Other Non-Destructive Techniques to Olives and Extra Virgin Olive Oil: A Systematic Review of Current Knowledge and Future Applications

Given its huge economic, nutritional, and social value, extra virgin olive oil (EVOO) is an essential food. This flagship product of the countries bordering the Mediterranean basin is one of the most frauded products worldwide. Although traditional chemical analyses have demonstrated to be reliable tools for olive drupes and EVOO quality assessment, they present several drawbacks; the urgent need for fast and non-destructive techniques thus motivated this review. Given the lack of comprehensive reviews in the literature, our first aim was to summarize the current knowledge regarding applying spectroscopies, imaging analyses, and other non-destructive techniques to olives and EVOO. The second aim was to highlight the most innovative and futuristic applications and outline the future research prospects within this strategic production chain. With respect to olive drupes, the most interesting results were obtained using RGB imaging and NIR spectroscopy, particularly using portable NIR devices and specific digital cameras for in-field or in-mill monitoring. Nevertheless, it is important to highlight that RGB imaging and NIR spectroscopy need to be integrated with flesh hardness measurements, given the higher reliability of this parameter compared to olive skin color. Finally, with respect to EVOO, although several useful applications of visible imagining, UV–Visible, NIR, and Mid-Infrared spectroscopies have been found, the online monitoring of EVOO quality using NIR spectroscopy strikes us as being the most interesting technique for improving the EVOO production chain in the near future.

Shedding light on the ageing of extra virgin olive oil: Probing the impact of temperature with fluorescence spectroscopy and machine learning techniques

This work systematically investigates the oxidation of extra virgin olive oil (EVOO) under accelerated storage conditions with UV absorption and total fluorescence spectroscopy. With the large amount of data collected, it proposes a method to monitor the oil's quality based on machine learning (ML) applied to highly-aggregated data.EVOO is a high-quality vegetable oil that has earned worldwide reputation for its numerous health benefits and excellent taste. Despite its outstanding quality, EVOO degrades over time due to oxidation, which can affect both its health qualities and flavour. Therefore, it is highly relevant to quantify the effects of oxidation on EVOO and develop methods to assess it that can be easily implemented under field conditions, rather than in specialized analytical laboratories.The ML approach indicates that the two excitation wavelengths (480 nm) and (300 nm) exhibit the maximum relative change in fluorescence intensity during the ageing for the majority of the oils, thus identifying the wavelengths which are more informative for quality prediction. Also, the paper proposes a method for the prediction of olive oil quality using highly-aggregated data. Such a method is of interest because it paves the way to the realization of a low-cost, portable device for in-field quality control.The following study demonstrates that fluorescence spectroscopy has the capability to monitor the effect of oxidation and assess the quality of EVOO, even when the data are highly aggregated. It shows that complex laboratory equipment is not necessary to exploit fluorescence spectroscopy using the proposed method and that cost-effective solutions, which can be used in-field by non-scientists, could provide an easily-accessible assessment of the quality of EVOO.

A targeted foodomic approach to assess differences in extra virgin olive oils: Effects of storage, agronomic and technological factors

Extra virgin olive oil (EVOO) quality and composition are mainly affected by genetics, agronomic and technological parameters, undergoing further modifications during storage. In this work, a chemometric approach was applied to study the impact of olive maturity, malaxation time/temperature, and oil storage on the quality and compositional parameters of Arbequina EVOO (basic quality indices, volatile and sensory profiles, contents in phenolic compounds, squalene, vitamin E and fatty acids). Storage emerged as the most influential factor, followed by olive maturity and malaxation temperature, while malaxation time had almost no effect. Storage at room temperature had a significant impact on the phenolic profile and quality parameters, mainly the peroxide value and K270. The determination of K270, an indicator of secondary oxidation products, was relevant to analyze the effect of storage conditions. Volatile compounds and fatty acids were good markers of ripeness, and the volatile profile was highly affected by malaxation temperature.

Effects of Filtration Processes on the Quality of Extra-Virgin Olive Oil-Literature Update.

Filtration is a process that eliminates solid sediments and moisture in olive oil to maintain its shelf life during storage. The influence of filtration on the oil characteristics is linked to many parameters such as chemical and sensory traits, cultivars and filtration systems. After assessing the literature on filtration research, we observed that there are contrasting findings and it is complicated to answer the question of whether to filter or not. An analysis of the influence of different filtration technologies used in extra-virgin olive oil production on the phenolic compounds, volatile fractions, antioxidant activity and sensory characteristics is given in this review. The information compiled could help olive oil producers to enhance extra-virgin olive oil quality and maintain it during storage.

Assessment of extra virgin olive oil quality by miniaturized near infrared instruments in a rapid and non-destructive procedure

Food fraud in olive oil is a major concern for consumers and authorities due to the health risks and economic impacts. Common frauds include blending with other cheaper non-olive oils, or misleading labelling. The main issue is that legislation and methods presently used in routine laboratories are not always up to date with current fraudulent practices, making detection difficult, so new analytical methods development is required.This study focuses on developing an affordable and non-destructive analysis method based on NIR spectroscopy and chemometrics for EVOO quality assessment, specifically by monitoring 7 parameters of interest in EVOO measured by official methods and used to develop calibrations through NIR data. For this, two NIR low-cost portable instruments were employed, studied in-depth and compared with a NIR benchtop instrument. Calibration results enabled detection of atypical olive oils and excellent accuracy, especially for palmitic and oleic acid predictions, demonstrating the potential of the instruments.

Thermal Effects on the Quality Parameters of Extra Virgin Olive Oil Using Fluorescence Spectroscopy.

Extra virgin olive oil is one of the superlative due to its health benefits. In this work, the Fluorescence spectra of extra virgin olive oil (EVOO) from different olive growing regions of Pakistan and Al-Jouf region from the Kingdom of Saudi Arabia (KSA) were obtained. The emission bands depicted relative intensity variations in all non-heated and heated EVOO samples. Prominent emission bands at 385, 400, 435 and 470nm represent oxidized products of fatty acids, bands at 520 and 673nm has been assigned to beta carotene and chlorophyll isomers respectively. All EVOO samples collected from Al-Jouf region, KSA and from Pakistan (Loralai Baluchistan, Barani Agricultural Research Institute, Chakwal and Morgha Biodiversity Park, Rawalpindi) regions showed thermal stability. Other EVOO samples from Chaman Baluchistan and one sample from wild specie (Baluchistan) bought directly from farmers showed denatured spectra even without heating. Chemical characteristics of all EVOO samples changed significantly at 200°C. Relatively, EVOO samples from Al-Jouf showed more thermal stability which might be due to geographical distribution, environmental effects, genetic background and processing or storage conditions. These results demonstrated fluorescence spectroscopy as a quick, cost-effective and reliable approach to assess the quality and thermal stability of EVOO. These characteristics of fluorescence spectroscopy may lead to the development of portable device for the onsite monitoring of EVOO.

Influence of Regulated Deficit Irrigation on Arbequina’s Crop Yield and EVOOs Quality and Sensory Profile

Regulated deficit irrigation in super-high-density (SHD) olive orchards is a well-known strategy to save water and control plant vigor, without decreasing fruit or oil yield. As there is controversial information about its influence on virgin olive oil quality, a trial was conducted in five SHD olive orchards of Arbequina cultivar in different locations of central, east, north and northeast Spain under full irrigation (FI) and regulated deficit irrigation (RDI) treatments. RDI applied during phase II of fruit growing (40% of total needs) saves more than 20% of water on average, without reductions in olive fruit or extra virgin olive oil (EVOO) yield. No threshold of 3.5 MPa of stem water potential was crossed in any case. RDI modified sterols and the fatty acid profile of EVOOs but not phenols, quality parameters, or the sensory profile. Latitude, altitude, and yearly rainfall have a big impact on some compounds such as campesterol, oleuropein, or margaroleic or linolenic acids.

Effect of oil-born yeasts on the quality of extra-virgin olive oils of Basilicata region

The olive oil microbiota mainly consists of yeasts, which may positively or negatively affect the physicochemical and sensory features of product.In this study, 17 yeast strains belonging to Candida boidinii, Lachancea fermentati, Nakazawaea molendinolei, N. wickerhamii and Schwanniomyces polymorphus species were collected during olive oil production, identified and tested for the ability to ferment sugars, to grow at low temperatures, for the occurrence of different enzymatic activities, for the tolerance and degradation of phenolic compounds, radical scavenging activities, biofilm formation, survival to simulated gastro-intestinal (GIT) tract. Yeasts were also inoculated in extra virgin olive oils (EVOO; from Leccino and Coratina cultivar) to evaluate their survival and their effect on EVOO quality (changes in analytical indices) during 6-months of storage.Most of strains were able to grow at 15°C, while the ability to ferment different sugars was strain-specific. All strains had β-glucosidase activity, while none exhibited lipolytic activity; peroxidase was widespread among the strains, while protease activity was strain-dependent. Esterase and the ability to hydrolyse oleuropein and form hydroxytyrosol was present only in N. wickerhamii strains. All strains were able to survive in olive mill wastewater, used as a model of phenolic compounds-rich matrix. A potential biofilm formation was observed only in N. wickerhamii, while the ability to scavenge radical and to cope with GIT-associated stresses were strain-dependent.High levels of survival were observed for almost strains (except S. polymorphus), in both Leccino and Coratina samples. Yeasts limited the acidity rise in olive oils, but overtime they contributed to increase the parameters related to oxidative phenomena (i.e. peroxides, K232, K270), resulting in a declassification of EVOOs. The total phenolic content (TPC) was correlated to the presence of yeasts and, at the end of storage period (6 months) inoculated samples had significantly lower concentrations compared to the control oils.This study confirms that yeasts are able to survive in olive oils and, therefore, the control of their occurrence during extraction process and storage conditions is needed to obtain high-quality products and to maintain the standards of EVOO classification.

Pulsed electric field increases the extraction yield of extra virgin olive oil without loss of its biological properties.

Pulsed electric field (PEF) has been used for improving extraction of extra virgin olive oil (EVOO). However, the biological changes induced by the consumption of pulsed electric field-obtained extra virgin olive oil (PEFEVOO) have not been studied yet. EVOO oils from Empeltre variety were prepared by standard (STD) cold pressure method involving crushing of the olives, malaxation and decanting and by this procedure including an additional step of PEF treatment. Chemical analyses of EVOO oils were done. Male and female Apoe-deficient mice received diets differing in both EVOOs for 12 weeks, and their plasma, aortas and livers were analyzed. PEF application resulted in a 17% increase in the oil yield and minimal changes in chemical composition regarding phytosterols, phenolic compounds and microRNA. Only in females mice consuming PEF EVOO, a decreased plasma total cholesterol was observed, without significant changes in atherosclerosis and liver steatosis. PEF technology applied to EVOO extraction maintains the EVOO quality and improves the oil yield. The equivalent biological effects in atherosclerosis and fatty liver disease of PEF-obtained EVOO further support its safe use as a food.

Lutein/β-carotene ratio in extra virgin olive oil: An easy and rapid quantification method by Raman spectroscopy

Carotenoids play an important role in the stability, freshness, and nutritional value of extra-virgin olive oil (EVOO). However, the carotenoid content in EVOO changes over time as a function of olive ripening and degrading events. A reliable quality marker is the ratio between the two most abundant carotenoids, namely lutein and β-carotene, since the second degrades more rapidly. Thus, to obtain a fast quantification of the lutein/β-carotene ratio in olive oil could deserve a certain interest. Resonant Raman spectroscopy is a rapid and non-destructive technique, widely applied for food chemical characterization. In this work, using high-performance liquid chromatography and UV–vis absorption spectroscopy as calibration techniques, we present a reliable method to assess the lutein/β-carotene ratio in EVOO using a single Raman spectrum. The novel approach deserves several methodological and applicative interests, since it would allow rapid, on-site screening of EVOO quality and authenticity, especially if implemented as a portable system.

Quality assessment and geographical origin classification of extra-virgin olive oils imported into China

Extra-virgin olive oil (EVOO) is an important imported commercial product in China. This study comprehensively evaluated the quality of EVOOs imported from different countries into China based on chemical parameters and sensory attributes. Multivariate statistics were used to authenticate their geographical origins. 71.8% of the oils failed to meet the current official standards at inland and abroad established for commercial EVOO category. Pyropheophytin, defect attributes, peroxide value, and K270 were above the limits in 32%, 24%, 23%, and 5% of the failed samples respectively, while free acidity, K232 and delta K were above the limits in 4%. Fatty acids and delta ECN42 were beyond the limits in 2% of the failed samples. Linear discriminant analysis (LDA) and orthogonal partial least squares discriminant analysis (OPLS-DA) based on fatty acids and triacyglycerols succeeded in identifying the origin of olive oils. 3.5% of the total might be mislabelled the geographical origin. The main quality problems of the analyzed oils include oxidation, counterfeiting with refined oils and origin fraud. Considering the results and the fact that most EVOOs in China are imported from other countries, chemometrics combined with critical quality attributes should be an ideal way of EVOO quality control, protecting consumers from frauds.

Investigation on the Effects of a Pulsed Electric Field (PEF) Continuous System Implemented in an Industrial Olive Oil Plant.

The aim of this study was to investigate how the treatment of olive paste of the Picholine variety with pulsed electric fields (PEF) under real operating conditions in a large-scale olive oil extraction plant affects the extractability, chemical composition and sensory profile of the oils. The application of pulsed electric fields (PEF) as a non-thermal food processing technology is interesting for many food extraction processes. The results of this study show that pulsed electric fields can be used as a pretreatment before oil separation to increase the extractability of the process and improve the content of functional components. The application of pulsed electric field (PEF) treatment (2.4 kV/cm, 4 kJ/kg, 6 µs pulse width) to olive paste through a continuous system significantly increased the extractability and total concentration of phenols (especially oleuropein derivatives) compared to the control. In addition, the volatile compounds, α-tocopherol, the fatty acid profile and the main legal quality parameters of extra virgin olive oil (EVOO), including free acidity, peroxide values, extinction indices and sensory analysis, were evaluated. The pulsed electric fields (PEF) treatment did not modify these EVOO quality parameters, neither the α-tocopherol content nor the volatile profile. The sensory properties of EVOO were not affected as well as the PEF treatment showed a similar intensity of fruity and pungent attributes without any off-flavor according to the European Union legal standards. An increase in the bitter taste attribute was observed in the PEF oils. Consequently, this study demonstrates that pulsed electric fields (PEF) processing could be implemented in olive oil processing as pretreatment for improving the efficiency of the process.

Elucidation of Olive Oil Oxidation Mechanisms by Analysis of Triacylglycerol Hydroperoxide Isomers Using LC-MS/MS.

Despite the importance of the insight about the oxidation mechanisms (i.e., radical and singlet oxygen (1O2) oxidation) in extra virgin olive oil (EVOO), the elucidation has been difficult due to its various triacylglycerol molecular species and complex matrix. This study tried to evaluate the mechanisms responsible for EVOO oxidation in our daily use by quantitative determination of triacylglycerol hydroperoxide (TGOOH) isomers using LC-MS/MS. The standards of dioleoyl-(hydroperoxy octadecadienoyl)-triacylglycerol and dioleoyl-(hydroperoxy octadecamonoenoyl)-triacylglycerol, which are the predominant TGOOHs contained in EVOO, were prepared. Subsequently, fresh, thermal-, and photo-oxidized EVOO were analyzed. The obtained results mostly agreed with the previously reported characteristics of the radical and 1O2 oxidation of linoleic acid and oleic acid. This suggests that the methods described in this paper should be valuable in understanding how different factors that determine the quality of EVOO (e.g., olive species, cultivation area, cultivation timing, and extraction methods) contribute to its oxidative stability.

Investigation of the Effectiveness of a Vertical Centrifugation System Coupled with an Inert Gas Dosing Device to Produce Extra Virgin Olive Oil

Recent decades have seen the development of many effective and innovative technologies for extra virgin olive oil (EVOO) extraction. Various solutions have been proposed to remove dissolved oxygen from the oil. Given these issues, we have designed and developed a system that can be added to the centrifuges that are already used in the olive oil industry. The system reduces the oxidative impact through the release of a technical gas inside the separator, and consequently delays the onset of defects related to oxidation. The experiment tested different N2 flow rates, directly into the vertical centrifuge, and four levels of N2 were tested–a control level (no N2 injection); low (20 L/min), medium (40 L/min), and maximum (80 L/min)–in order to evaluate the effectiveness of this new technique on EVOO quality. This experiment demonstrates that the objectives have been achieved. The EVOO produced using our system had lower dissolved oxygen content with N2 injection, along with an enriched volatile fraction, and higher biophenol concentrations. The chemical analyses were confirmed by a sensory analysis, with an increase in fruity intensity and bitter taste.

Simulation of Transport under Different Temperature Conditions: Effects on Extra Virgin Olive Oil Quality

AbstractExtra virgin olive oil (EVOO) is imported/exported globally. However, little is known about the qualitative effects of the transport conditions, and, consequently, they are not usually controlled. This study simulates temperature fluctuations in summer (18–42.5 °C, 12 h–12 h, one week) and winter (4–16.5 °C, 12 h–12 h, one week), to examine their effect on EVOO quality. The EVOO samples undergo evaluation with chemical analyses before and immediately after treatment and after 24 weeks of storage (at room temperature in the dark). The simulated summer conditions cause oil oxidation. This situation bears a connection to an increased lipid oxidation rate, peroxide value, 1.2/1.3 diacylglycerol ratio, rancid score, and rancid‐related volatile compounds. The simulated winter conditions also cause oil oxidation. In this case, the rancid score and the rancid‐related volatile compound content show similarities to the samples exposed to the simulated summer conditions. In winter conditions, the temperature fluctuations seem to play a key role in the rancid defect appearance. Eleven of the 15 (summer) and 10 of the 15 (winter) samples are downgraded from the category of “extra virgin” to “virgin” after 24 weeks of bottle storage.Practical applications: Transportation conditions constitute a critical factor in determining extra virgin olive oil quality. Transport is a critical control point in maintaining the quality of extra virgin olive oil, which can be transported without any specific controls. The obtained results improve the knowledge regarding the risks related to transport in hot and cold seasons, assessing the oxidative damages in both conditions on three different cultivars. A better understanding of the degradation phenomena during transportation helps develop specific technologies and practices (e.g., controlled‐temperature transportation, thermal insulation materials, use of digi‐sense nonreversible temperature labels, and so on) to counter the phenomena and evaluate the costs and limits of the existing protocols.

The Use of a Cooling Crusher to Reduce the Temperature of Olive Paste and Improve EVOO Quality of Coratina, Peranzana, and Moresca Cultivars: Impact on Phenolic and Volatile Compounds

A new technology used to reduce the temperature of olive paste was applied to the extra virgin olive oil (EVOO) mechanical extraction process. The performance of a cooling crusher that was able to counteract the thermal increase that occurs during olive fruit grinding was analyzed to evaluate the effects on the development of volatile compounds and the concentration of hydrophilic phenols in the final product. The volatile profiles and phenolic fraction of EVOOs extracted from three different cultivars (Coratina, Peranzana, and Moresca) were positively affected by the use of lower temperatures during the crushing phase. The volatile fractions showed increases in the total aldehydes, mainly related to the concentrations of (E)-2-hexenal, and reductions in the total alcohols, mainly due to 1-penten-3-ol, 1-hexanol and (Z)-3-hexen-1-ol contents. The use of a lower temperature reduced the level of oxidative processes, protecting the phenolic compounds in the Moresca and Peranzana EVOOs by 17.8 and 12.1%, respectively.

Extra Virgin Olive Oil from Destoned Fruits to Improve the Quality of the Oil and Environmental Sustainability.

The world production of olive oil represented 3.1 million tons in 2021 and the choice aimed at high quality extra virgin olive oils is increasingly appearing (IOC, 2022). Moreover, the production of a product of quality with environmental respect is grown in demand. Consequently, the so-called “ecological” processes mostly interest the production market of extra virgin olive oils. Despite the current processing and extraction technologies, the characteristics of olive oil can still be optimized. In this regard, interesting technology to produce olive oil remains the stone removal of the olives before the extraction of the oil. Recently, the destoners preserved a less low oil yield. In light of recent progress, the review focuses on the influence of destoning on the quality of extra virgin olive oil, using a systematic approach. Interest in this technology is increasing and many researchers report that destoned olive oils show superior characteristics confronting with those obtained by the traditional method. These data indicate that destoning is one of the most significant advantages for the improvement of the oil qualitative traits and the system’s sustainability.

Demonstration of the Effectiveness of a Pilot, Variable Speed Crusher Featuring an In‐Line Oxygen Dosing System

AbstractAt the industrial scale, improvements to extra virgin olive oil (EVOO) processing are an important opportunity to increase both added‐value, and the product's organoleptic and chemical parameters. Concerning all the operations used during EVOO extraction, crushing and malaxation have an effect on the extraction efficiency and minor components composition extremely significant. In this context, a pilot industrial‐scale crusher is designed and developed that can control the amount of oxygen that is dosed directly into the produced olive paste. In this study, the effectiveness of this new technique, combined with different crushing speeds on EVOO quality, is evaluated. It is demonstrated that supplying oxygen to the paste enriches the volatile fraction, the mean increase is about 30% for the compounds associated to positive sensory notes, while the concentrations of the compounds associated to sensory defects are stationary on 5.2 mg kg−1.Practical Applications: This result is confirmed by a sensory analysis, notably an increase in fruity intensity. It is also shown that crushing speed affects the extraction of compounds such as biophenols, and increases the bitter taste. Increased bitterness is detected for samples crushed at 3500 rpm compared to those crushed at lower speed (mean 5.7±0.3 compared to 4.5±0.4).

Extra virgin olive oil under simulated consumption conditions: Evaluation of quality, health, and flavour properties

The present study investigated the changes in extra virgin olive oil (EVOO) quality, health, and flavour properties during simulated domestic consumption conditions in which the EVOO bottles were reopened daily, thereby gradually increasing the headspace. Quality parameters, phenolic and volatile compounds, and sensory attributes of two monovarietal EVOOs, Istarska bjelica (IB) and Buža (B), have been evaluated every seven days for one month. After storage, the total phenolic content decreased by 12.3% and 17.6% in IB and B EVOOs, respectively, while the total concentration of volatile compounds decreased by approximately 19%. However, the results have shown that no enhanced degradation of phenolic and volatile compounds has been noted in EVOOs stored under consumption conditions compared to the ones stored unopened during the same period, implying that the degradation degree was predominantly attributed to oil aging. The principal component analysis emphasised peroxide value and sensory attributes as parameters that segregated EVOOs under consumption conditions from the fresh and unopened ones. Furthermore, the conditions in which EVOO was consumed in a recommended daily dosage (20 g) during one-month storage did not reduce its phenolic content under the levels required for the EFSA health claim application.

An Innovative Malaxer Equipped with SCADA Platform for Improving Extra Virgin Olive Oil Quality.

Agriculture 4.0 is gaining more attention, and all companies are thinking about innovating machines to increase income and improve the quality of the final products. In the agro-food sector, there is space for innovation, as it is far behind the industrial sector. This paper reports an industrial-scale study on the application of an innovative system for the extraction of Sicilian EVOO (extra virgin olive oil) to improve both process management and the quality of the product. Based on previous studies, the authors suggested an innovative machine equipped with a SCADA (supervisory control and data acquisition system) for oxygen and process duration monitoring and control. The objective of the research was thus to discuss the development of a SCADA platform applied to the malaxer and the establishment of an optimized approach to control the main process parameters for obtaining high-quality EVOO. The SCADA system application in the EVOO extraction process allowed a qualitative improvement of the Sicilian EVOO of Nocellara del Belice and Cerasuola cultivars. The use of the innovative system made it possible to increase the values of tocopherols (by about 25%) in Cerasuola cultivar and total phenol content (by about 30%) in Nocellara del Belice cultivar EVOOs.