New approaches to virgin olive oil quality, technology, and by-products valorization

Potential of the Oxidized Form of the Oleuropein Aglycon to Monitor the Oil Quality Evolution of Commercial Extra-Virgin Olive Oils

The quality of commercially available extra-virgin olive oils (VOOs) of different chemical compositions was evaluated as a function of storage (12 months), simulating market storage conditions, to find reliable and early markers of the virgin olive oil (VOOs) quality status in the market. By applying a D-optimal design using the Most Descriptive Compound (MDC) algorithm, 20 virgin olive oils were selected. The initial concentrations of oleic acid, hydrophilic phenols, and α-tocopherol in the 20 VOOs ranged from 58.2 to 80.5%, 186.7 to 1003.2 mg/kg, and 170.7-300.6 mg/kg, respectively. K270, ∆K, (E, E)-2.4-decadienal and (E)-2-decenal, and the oxidative form of the oleuropein aglycon (3,4-DHPEA-EA-OX) reflected the VOO quality status well, with 3,4-DHPEA-EA-OX being the most relevant and quick index for simple monitoring of the "extra-virgin" commercial shelf-life category. Its HPLC-DAD evaluation is easy because of the different wavelength absorbances of the oxidized and non-oxidized form (3,4-DHPEA-EA), respectively, at 347 and 278 nm.

The Contribution of Theoretical Prediction Studies to the Antioxidant Activity Assessment of the Bioactive Secoiridoids Encountered in Olive Tree Products and By-Products

Assessment of the antioxidant activity of different types of natural compounds is a complex research area that encompasses various in vitro tests and in vivo studies. Sophisticated modern analytical tools permit the unambiguous characterization of the compounds present in a matrix. The contemporary researcher, knowing the chemical structure of the compounds present, can carry out quantum chemical calculations that provide important physicochemical information assisting the prediction of antioxidant potential and the mechanism behind the activity of target compounds before further experimentation. The efficiency of calculations is steadily improved due to the rapid evolution of both hardware and software. It is possible, consequently, to study compounds of medium or even larger size, incorporating also models that simulate the liquid phase (solution). This review contributes to the establishment of theoretical calculations as an inherent part of the antioxidant activity assessment process, having as a case study the complex mixtures of olive bioactive secoiridoids (oleuropein, ligstroside, and related compounds). The literature indicates great variability in theoretical approaches and models used so far for only a limited number of this group of phenolic compounds. Proposals are made for standardization of methodology (reference compounds, DFT functional, basis set size, and solvation model) to facilitate comparisons and communication of findings.

Effect of Controlled Oxygen Supply during Crushing on Volatile and Phenol Compounds and Sensory Characteristics in Coratina and Ogliarola Virgin Olive Oils

In virgin olive oil industries, the technological choices of the production plant affect the biochemical activities that take place in the olives being processed throughout the entire process, thereby affecting the quality of the final product. The lipoxygenase pool enzymes that operated their activity during the first phases of the process need the best conditions to work, especially concerning temperature and oxygen availability. In this study, a system was equipped to supply oxygen in the crusher at a controllable concentration in an industrial olive oil mill at pilot plant scale, and four oxygen concentrations and two cultivars, Coratina and Ogliarola, were tested. The best concentration for oxygen supply was 0.2 L/min at the working capacity of 0.64 Ton/h. Further, using this addition of oxygen, it was possible to increase the compound's concentration, which is responsible for the green, fruity aroma. The effect on volatile compounds was also confirmed by the sensory analyses. However, at the same time, it was possible to maintain the concentration of phenols in a good quality olive oil while also preserving all the antioxidant properties of the product due to the presence of phenols. This study corroborates the importance of controlling oxygen supply in the first step of the process for process management and quality improvement in virgin olive oil production.

Valorizing the usage of olive leaves, bioactive compounds, biological activities, and food applications: A comprehensive review

Olive oil production is a significant source of economic profit for Mediterranean nations, accounting for around 98 percent of global output. Olive oil usage has increased dramatically in recent years, owing to its organoleptic characteristics and rising knowledge of its health advantages. The culture of olive trees and the manufacture of industrial and table olive oil produces enormous volumes of solid waste and dark liquid effluents, involving olive leaves, pomace, and olive oil mill wastewaters. These by-products cause an economic issue for manufacturers and pose major environmental concerns. As a result, partial reuse, like other agronomical production wastes, is a goal to be achieved. Because these by-products are high in bioactive chemicals, which, if isolated, might denote components with significant added value for the food, cosmetic, and nutraceutical sectors, indeed, they include significant amounts of beneficial organic acids, carbohydrates, proteins, fibers, and phenolic materials, which are distributed differently between the various wastes depending on the olive oil production method and table olive agronomical techniques. However, the extraction and recovery of bioactive materials from chosen by-products is a significant problem of their reasonable value, and rigorous detection and quantification are required. The primary aims of this review in this context are to outline the vital bioactive chemicals in olive by-products, evaluate the main developments in extraction, purification, and identification, and study their uses in food packaging systems and safety problems.

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.

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.

Food-Derived Bioactive Molecules from Mediterranean Diet: Nanotechnological Approaches and Waste Valorization as Strategies to Improve Human Wellness

The beneficial effects of the Mediterranean diet (MedDiet), the most widely followed healthy diet in the world, are principally due to the presence in the foods of secondary metabolites, mainly polyphenols, whose healthy characteristics are widely recognized. However, one of the biggest problems associated with the consumption of polyphenols as nutraceutical adjuvant concerns their bioavailability. During the last decades, different nanotechnological approaches have been developed to enhance polyphenol bioavailability, avoiding the metabolic modifications that lead to low absorption, and improving their retention time inside the organisms. This review focuses on the most recent findings regarding the encapsulation and delivery of the bioactive molecules present in the foods daily consumed in the MedDiet such as olive oil, wine, nuts, spice, and herbs. In addition, the possibility of recovering the polyphenols from food waste was also explored, taking into account the increased market demand of functional foods and the necessity to obtain valuable biomolecules at low cost and in high quantity. This circular economy strategy, therefore, represents an excellent approach to respond to both the growing demand of consumers for the maintenance of human wellness and the economic and ecological exigencies of our society.

Evolution of the Olive Oil Industry along the Entire Production Chain and Related Waste Management

The production of olive oil involves the sustainable management of the waste produced along the entire production chain. This review examines the developments regarding cultivation techniques, production technologies, and waste management, highlighting the goals to be achieved and the most reasonable prospects. The results show that cultivation and production technology have evolved to an almost final solution to meet economic feasibility, keeping the oil’s high quality. Continuous horizontal decanters will coexist with traditional mills in many countries with old olive oil production and consumption traditions. High-quality products have conquered markets, especially in the wealthiest countries. At the same time, the exploitation of dried pomace by solvent extraction is increasingly an obsolete practice. However, waste management is still looking for one or a few reasonable solutions that meet modern society’s constraints. The enhancement of some experienced technologies and the full-scale application of emerging technologies and strategies should solve this problem in the short–medium term. A short discussion is reported on the possibility of unifying the nature and the quality of the waste, whatever the olive oil production method is. Furthermore, modern thermochemical treatment for solid wet organic waste disposal is examined and discussed.

Evaluation of Olive Oil Quality with Electrochemical Sensors and Biosensors: A Review

Electrochemical sensors, sensor arrays and biosensors, alongside chemometric instruments, have progressed remarkably of late, being used on a wide scale in the qualitative and quantitative evaluation of olive oil. Olive oil is a natural product of significant importance, since it is a rich source of bioactive compounds with nutritional and therapeutic properties, and its quality is important both for consumers and for distributors. This review aims at analysing the progress reported in the literature regarding the use of devices based on electrochemical (bio)sensors to evaluate the bioactive compounds in olive oil. The main advantages and limitations of these approaches on construction technique, analysed compounds, calculus models, as well as results obtained, are discussed in view of estimation of future progress related to achieving a portable, practical and rapid miniature device for analysing the quality of virgin olive oil (VOO) at different stages in the manufacturing process.

Quality Evaluation of Shrimp (Parapenaeus longirostris) Treated with Phenolic Extract from Olive Vegetation Water during Shelf-Life, before and after Cooking

The focus of this study was to assess the quality traits and sensory profile of cooked rose shrimps (Parapenaeus longirostris) treated with a phenolic extract, derived from olive vegetation water (PEOVW). To achieve the aim, four different groups of shrimps were analysed, specifically the control (CTRL) group, where the shrimps were soaked in tap water; sulphites (S) group with shrimps soaked in 0.5% sodium metabisulfite tap water solution, phenolic extract (PE) group where a tap water solution containing 2 g/L of phenols was used; and PE+S group where the shrimps were dipped in 0.25% sodium metabisulfite tap water solution containing 1 g/L of phenols. The groups were then stored at 2 °C and analysed on the day of packaging (D0), after 3 (D3), 6 (D6), and 8 (D8) days. On each group, microbiological parameters such as Enterobacteriaceae, mesophilic and psychrotrophic bacteria, and colorimetric indices were investigated on six (n = 6) shrimps before cooking, while the evolution of the phenolic content, antioxidant activity, and sensory analysis during the storage period were evaluated on cooked shrimps. Regarding colour coordinates, there were no noteworthy variations overtime nor between groups, while it is important to note that the microbiological results for the PE group showed at each time interval and for all the considered parameters, significantly lower values than the other groups (p < 0.05). This result is very interesting when considered further in correlation with the sensory analysis, where shrimps mainly in PE and secondarily in PE+S groups were shown to retain the freshness characteristics better than the other groups (α = 0.01), without giving the shrimps any particularly bitter and pungent sensations typical of the olive phenolic compounds. In conclusion, the results obtained in this study give PEOVW the potential to be valorised in the food sector and, above all, it could represent a sustainable solution to reduce the use of synthetic additives.

Overall quality evolution of extra virgin olive oil exposed to light for 10 months in different containers

Green glass (GG), ultraviolet grade absorbing glass (UVAGG), and multilayer (plastic-coated paperboard aluminium foil) (MLP) packagings were used for storing two commercially extra virgin olive oils (EVOOs) with different phenolic and volatile compound contents to evaluate their effect on oil quality evolution over 10 months of light exposure. Quality parameters such as free acidity, peroxide value, spectrophotometric indices, antioxidant and volatile compositions as well as sensory characteristics were evaluated; packaging material type and initial antioxidant composition significantly influenced EVOOs' resistance to oxidation, and consequently their quality. Compared with GG or UVAGG, MLP provided superior protection against oxidation; oils stored in MLP containers retained their characteristics within the regulatory limits and contained more antioxidants and fewer 'rancid' defect and related volatile compounds.

High vacuum-assisted extraction affects virgin olive oil quality: Impact on phenolic and volatile compounds

High vacuum technology has been incorporated into a new assisted extraction system applied to virgin olive oil (VOO) processing, which was tested at a lab-scale pilot plant to evaluate its impact on the physicochemical properties of the olive paste and oil. The vacuum system induced changes in the mechanical and structural properties of the olive cells, improving the coalescence of the oil droplets due to substantial cellular and intracellular mass transfer during the process, as shown by cryo-scanning electron microscopy (Cryo-SEM) analysis. The effects on the quality characteristics of VOOs extracted from three cultivars at different malaxation temperatures were evaluated. A significant increase in the phenolic content, from 25.2% to 48.6%, was observed. The content of volatile compounds responsible for the VOO flavor decreased as a function of malaxation temperature. The reduction of some volatile molecules related to the VOO off-flavor (ethanol, ethyl acetate and acetic acid) was also shown.

Antioxidants in Extra Virgin Olive Oil and Table Olives: Connections between Agriculture and Processing for Health Choices

: This review focuses on the conditions required to increase and maintain the antioxidant nutrients in both extra virgin olive oil (EVOO) and table olives (TOs) from the agronomic and technological practices to the gastronomy. The main antioxidants of TOs and EVOO are phenol alcohols and acids, secoiridoids, lignans and flavones, all of which possess the ability to prolong the oil's shelf-life and exhibit healthy properties for humans. The precise detection of secoiridoid derivatives remains the breakthrough for the nutritional and health quality certification of extra virgin olive oils (EVOOs) required for EFSA health claims. To attain the necessary antioxidant quality in both EVOO and TOs, it is necessary to hard focus on the several steps in the production chain, including olive cultivar, agronomic conditions, harvesting methods, and transformation technology. The quality level is maintained if the storage conditions aim to minimize the oxidative processes that occur due to oxygen and light. In terms of minor polar biophenols, there is disagreement on which between the organic or conventional EVOOs show higher concentration values. The strict disciplinary of production of protected designation EVOOs does not ensure higher phenol values in comparison to the artisanal EVOOs. In gastronomy, the EVOOs are preferable to seed oils, particularly during frying vegetable. The EVOOs show higher heat stability, linked both to the fatty acid composition and the phenol content, that is important for preventing fatty acids oxidation. Concerning TOs, the commercial presentation includes olives and olive paste. Both products show a remarkable loss of natural antioxidants after pasteurization and during storage as the thermal treatment mostly impacts on TOs secoiridoids.

Quality evolution of extra-virgin olive oils according to their chemical composition during 22 months of storage under dark conditions

The quality evolution of 14 extra-virgin olive oils (EVOOs), with different initial polyphenol and oleic acid (64.6-77.7%) levels, was determined during real-time storage in dark conditions at room temperature for 22 months. EVOOs with low (<20-200 mg/kg), medium (450-700 mg/kg), and high polyphenolic levels (750-1400 mg/kg) were used. We found high correlations among peroxide values, K₂₃₂, K₂₇₀, and storage time. Oleuropein derivatives decreased by 98%, 89%, and 85% in EVOOs with low, medium, and high polyphenolic levels, respectively, with the highest depletion occurring in those with the lowest initial concentrations. Besides having higher α-tocopherol protection from oxidative phenomena, EVOOs with the highest phenolic fractions showed lower head space accumulations of off-flavour volatile substances and thus demonstrated the best retention of sensory and health benefits. We propose that the shelf life of EVOOs can be determined from their initial levels of oleuropein derivatives.

Plasticity of fruit and oil traits in olive among different environments

Olive is a long-living perennial species with a wide geographical distribution, showing a large genetic and phenotypic variation in its growing area. There is an urgent need to uncover how olive phenotypic traits and plasticity can change regardless of the genetic background. A two-year study was conducted, based on the analysis of fruit and oil traits of 113 cultivars from five germplasm collections established in Mediterranean Basin countries and Argentina. Fruit and oil traits plasticity, broad-sense heritability and genotype by environment interaction were estimated. From variance and heritability analyses, it was shown that fruit fresh weight was mainly under genetic control, whereas oleic/(palmitic + linoleic) acids ratio was regulated by the environment and genotype by environment interaction had the major effect on oil content. Among the studied cultivars, different level of stability was observed, which allowed ranking the cultivars based on their plasticity for oil traits. High thermal amplitude, the difference of low and high year values of temperature, negatively affected the oil content and the oleic acid percentage. Information derived from this work will help to direct the selection of cultivars with the highest global fitness averaged over the environments rather than the highest fitness in each environment separately.

Obtaining an Extract Rich in Phenolic Compounds from Olive Pomace by Pressurized Liquid Extraction

The olive oil industry produces large volumes of wastes, which are also potential sources of bioactive compounds by developing healthy and/or functional foods. Extraction of phenolic compounds from the residues of the olive oil is mainly carried out with solvents. However, there is currently a growing public awareness about the use of organic solvents in food processing, which has pointed out the need for the application of clean technologies such as pressurized liquid extraction (PLE). Therefore, the aim of this research was to optimize the phenolic compound extraction from olive pomace by PLE, establishing the qualitative and quantitative phenolic profile by HPLC-ESI-TOF/MS. The extraction design to recover phenolics from olive pomace demonstrates a great compositional variability of PLE extracts obtained under different experimental conditions. Indeed, quantitative results have pointed out the selectivity of PLE extraction when this technique is applied to the treatment of olive pomace. PLE-optimized conditions showed higher total phenolic compound content than conventional extraction (1659 mg/kg d.w. and 281.7 mg/kg d.w., respectively). Among these phenolics, the quantity of secoiridoids and flavonoids in the optimized PLE extract was three and four times higher than in conventional extracts. Furthermore, optimal PLE conditions allowed to obtain an enriched hydroxytyrosol extract which was not detected in the conventional one.

Physicochemical characterization of virgin olive oil obtained using an ultrasound-assisted extraction at an industrial scale: Influence of olive maturity index and malaxation time

Ultrasound-assisted extraction is an innovative technique applied to the extraction process for virgin olive oil (VOO), which is generally employed to increase plant efficiency and improve product quality. A high-power ultrasound (US) device was introduced at an industrial plant that can process at 2 tons/h to evaluate the technique's physicochemical impact on quality parameters of VOO that was caused by an intensive mass transfer induced by acoustic cavitation process and shockwaves. The impact on oil yield was also evaluated with respect to the ripening stage and malaxation time. No significant effects on the legal and commercial parameters of VOO (including quality indices, sterols, triterpene dialcohols, waxes and diacylglycerols) were found for olives at medium-early ripening stage. Significant physical changes, increased extraction yield (22.7%), enhanced phenol content (10.1%) were observed in US-VOO compared to control (C) oil extracted with a traditional process at an early maturity index.

Cooling treatment of olive paste during the oil processing: Impact on the yield and extra virgin olive oil quality

In recent years, the temperature of processed olives in many olive-growing areas was often close to 30°C, due to the global warming and an early harvesting period. Consequently, the new trends in the extraction process have to include the opportunity to cool the olives or olive paste before processing to obtain high quality EVOO. A tubular thermal exchanger was used for a rapid cooling treatment (CT) of olive paste after crushing. The results did not show a significant difference in the oil yield or any modifications in the legal parameters. The cooling process determined a significant improvement of phenolic compounds in all the three Italian cultivar EVOOs analyzed, whereas the volatile compounds showed a variability largely affected by the genetic origin of the olives with C₆ aldehydes that seem to be more stable than C₆ alcohols and esters.