Olive Oil Processing: Current Knowledge, Literature Gaps, and Future Perspectives

Exploring the relevance of the type of horizontal separator to optimize the extraction efficacy for the Arbequina variety

The productivity of virgin olive oil depends not only on agronomic factors but also on the technological factors of the extraction process. The 'Arbequina' variety has extractability problems, which is a challenge for master millers anywhere. This work aims to evaluate the behavior of different decanters and seeks to modulate the effect of some processing parameters and their interactions with oil extraction efficiency in the case of 'Arbequina.' Fruit characteristics, processing parameters, and extractability were collected over 10 years from 38 decanters that belong to five different brands. The results have shown that fruit moisture is the most relevant factor for oil extractability, especially over 52%. Furthermore, extractability is positively correlated with malaxing temperature, addition of water, and total fat content in the fruit. However, the results show that before applying a regulation, the type of decanter must be considered. The model used in this study has allowed us to optimize the regulations for each type of decanter to reduce oil losses within the pomace, achieving an extraction efficiency within the range of 78%-91.5%. In fact, the best extraction efficiency results (91.5%) were obtained by processing at temperatures >26°C and water injection of 5%.

Stability of monovarietal Sicilian olive oils under different storage condition: Chemical composition, sensory characteristics, and consumer preference

Monovarietal olive oils, known for their distinct aromatic profiles, face challenges in preserving their initial quality due to variations in stability and susceptibility to oxidative deterioration. This study focused on the storage stability of two Italian cultivars, 'Biancolilla' and 'Cerasuola', from Sicily, chosen for their aromatic complexity and divergent storage stability. Oils, whether filtered or unfiltered, underwent storage at two thermal regimes (18 °C and - 20 °C) over a year. The combination of filtration and low-temperature storage was employed to mitigate oxidative deterioration and hydrolytic processes, as filtration removes suspended particles and emulsified water, while low temperatures slow down enzymatic activities and oxidative reactions, thereby enhancing the overall stability and shelf life of the olive oils. Unfiltered samples at room temperature showed a significant increase in secoiridoid aglycone derivatives (Hydroxytyrosol and Tyrosol) due to hydrolytic processes, along with a decrease in secoiridoid aglycone. Filtration delayed these processes, with a more pronounced effect observed when combined with -20 °C storage. Sensory analysis identified the emergence of the "fusty" defect in the less resilient 'Biancolilla' cultivar after six months, a phenomenon mitigated by filtration and freezing. Consumer tests validated these findings. In summary, the synergistic approach of combining filtration with low-temperature storage emerges as a promising strategy for maintaining high-quality standards, especially for less stable monovarietal extra virgin olive oils. This strategy ensures compliance with EU regulations beyond the conventional 12-month shelf life, offering a practical solution for preserving the nutritional and sensory quality of olive oil.

The Composition of Volatiles and the Role of Non-Traditional LOX on Target Metabolites in Virgin Olive Oil from Autochthonous Dalmatian Cultivars

The lipoxygenase pathway has a significant influence on the composition of the volatile components of virgin olive oil (VOO). In this work, the influence of the maturity index (MI) on the activity of the lipoxygenase enzyme (LOX) in the fruits of the autochthonous Dalmatian olive cultivars Oblica, Levantinka and Lastovka was studied. The analysis of the primary oxidation products of linoleic acid in the studied cultivars showed that LOX synthesises a mixture of 9- and 13-hydroperoxides of octadecenoic acid in a ratio of about 1:2, which makes it a non-traditional plant LOX. By processing the fruits of MI~3, we obtained VOOs with the highest concentration of desirable C6 volatile compounds among the cultivars studied. We confirmed a positive correlation between MI, the enzyme activity LOX and the concentration of hexyl acetate and hexanol in cultivars Oblica and Lastovka, while no positive correlation with hexanol was observed in the cultivar Levantinka. A significant negative correlation was found between total phenolic compounds in VOO and LOX enzyme activity, followed by an increase in the MI of fruits. This article contributes to the selection of the optimal harvest time for the production of VOOs with the desired aromatic properties and to the knowledge of the varietal characteristics of VOOs.

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.

Application of Pulsed Electric Fields to Pilot and Industrial Scale Virgin Olive Oil Extraction: Impact on Organoleptic and Functional Quality

The quality of virgin olive oil (VOO) is largely determined by the technology used in the industrial process of extracting the oil. Technological innovations within this field aim to strike a proper balance between oil yield and the optimal chemical composition of VOO. The application of pulsed electric fields (PEF) that cause the electroporation of the plant cell membranes favors a more efficient breakage of the olive fruit tissue, which in turn could facilitate the extraction of the oil and some of its key minor components. Pilot-scale and industrial extraction tests have been conducted to assess the effect of PEF technology on the oil extraction yield and on the organoleptic and functional quality of VOO. The best results were obtained by combining the PEF treatment (2 kV/cm) with short malaxation times and a low processing temperature. Under these conditions, PEF technology could decisively improve the oil yield by up to 25% under optimal conditions and enhance the incorporation of phenolic and volatile compounds into the oils. The PEF treatment neither affected the physicochemical parameters used to determine the commercial categories of olive oils, nor the tocopherol content. Similarly, the sensory evaluation of the PEF-extracted oils by means of a panel test did not detect the appearance of any defect or off-flavor. In addition, the intensity of positive attributes (fruity, bitter and pungent) was generally higher in PEF oils than in control oils.

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.

Volatile profile and quality characteristics of the Greek “Chondrolia Chalkidikis” virgin olive oils: effect of ripening stage

Among the various parameters affecting olive oil quality, ripening stage is one of the most important. Optimal harvest time ensuring target quality for the final product varies in relation to the effect of many intrinsic and extrinsic factors. Therefore, its determination necessitates thorough examination of each case. The present study explores the impact of six harvest times on volatile profile and quality attributes of olive oils from “Chondrolia Chalkidikis” Greek cultivar. All samples examined were classified “Virgin Olive Oils” (VOOs) according to findings of acidity, peroxide, and K values. The low values for the principal official quality indices, the high oleic acid percentages (76–78%), the high oxidative stabilities (up to 36 h induction period), and phenols content (606–290 mg/kg) were considered nutritionally promising. Total phenols, carotenoids and chlorophylls contents, as well as oxidative stability (induction period values) decreased with ripening. Harvest time had a strong impact on HS-SPME–GC–MS volatile fingerprint. Optimal volatile profiles were related to intermediate examined ripening stages. Fatty acid composition did not show remarkable trends. Chondrolia Chalkidikis VOOs perform as interesting candidates of high quality. Findings of the study may support existing databases with scientific records for Chondrolia Chalkidikis VOOs, boost their competitiveness in the global market, and encourage worldwide exploitation of VOOs from similar cultivars (table olives oriented).

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.

A Review on High-Power Ultrasound-Assisted Extraction of Olive Oils: Effect on Oil Yield, Quality, Chemical Composition and Consumer Perception

The objective of this review is to illustrate the state of the art in high-power ultrasound (HPU) application for olive oil extraction with the most recent studies about the effects of HPU treatment on oil yield, quality, chemical composition, as well as on the consumer's perception. All the examined works reported an increase in oil yield and extractability index through the use of HPU, which was ascribed to reduced paste viscosity and cavitation-driven cell disruption. Olive oil legal quality was generally not affected; on the other hand, results regarding oil chemical composition were conflicting with some studies reporting an increase of phenols, tocopherols, and volatile compounds, while others underlined no significant effects to even slight reductions after HPU treatment. Regarding the acceptability of oils extracted through HPU processing, consumer perception is not negatively affected, as long as the marketer effectively delivers information about the positive effects of ultrasound on oil quality and sensory aspect. However, only a few consumers were willing to pay more, and hence the cost of the innovative extraction must be carefully evaluated. Since most of the studies confirm the substantial potential of HPU to reduce processing times, improve process sustainability and produce oils with desired nutritional and sensory quality, this review points out the need for industrial scale-up of such innovative technology.

Neuroprotective effects of oleuropein: Recent developments and contemporary research

Neurological disorders are increasing at a faster pace due to oxidative stress, protein aggregation, excitotoxicity, and neuroinflammation. It is reported that the Mediterranean diet including olives as a major dietary component prevents and ameliorates neurological anomalies. Oleuropein is the major bioactive component in different parts of the Olive (Olea europaea L.) tree. Several mechanisms have been reported for the neuroprotective role of oleuropein including induction of apoptosis and autophagy, enhancing the antioxidant pool of the cerebral region, decreasing the unnecessary release of proinflammatory cytokines and chemokines by deactivating the microglia cells and astrocytes thus preventing the occurrence of neuroinflammation. Regular intake of oleuropein seems to be correlated with decreased risks of neural disorders including Alzheimer's, Parkinson's, strokes, depression, anxiety, epilepsy, and others. This review majorly discusses the chemistry, biosynthesis, and metabolism of oleuropein along with an updated vision of its neuroprotective role in counteracting the acute and chronic neurodegenerative and neuropsychiatric disorders. Moreover, mechanisms by which oleuropein may prevent neurodegeneration are reviewed. PRACTICAL APPLICATION: Neurological disorders are negatively affecting the health and life quality of individuals around the globe. Although various medicinal solutions are available to tackle such ailments, none has proven to fully cure and being deprived of side effects. In this respect, the prevention of such disorders using natural remedies may be an effective strategy to overcome the incidence of the increasing cases. Furthermore, the natural compounds provide a safer alternative to pharmaceutical drugs. Hence, oleuropein from olive tree products is found to be efficacious against neurological disorders. This review provides an updated insight on the positive effects of oleuropein against neurodegenerative and neuropsychiatric disorders. The diet practitioners and nutraceutical companies may benefit from the provided information to design and develop strategies to improve the mental health of suffering individuals.

Application of Low Temperature during the Malaxation Phase of Virgin Olive Oil Mechanical Extraction Processes of Three Different Italian Cultivars

The malaxation step, one of the most important phases of the virgin olive oil (VOO) mechanical extraction process involved in the development of the main quality characteristics of the final product, was carried out at a low temperature (18 °C). The rapid control of malaxer temperature was handled with the same chiller as that of the heat exchanger used in a semi-industrial extraction plant. Low temperature was used during the full olive paste kneading process and also for half of this process, which showed that there was a significant impact on the phenolic and volatile contents of VOO. Trials were conducted on three different cultivars (Canino, Moraiolo and Peranzana), and their phenolic and volatile concentrations showed different quantitative and qualitative effects due to the prolonged use of low temperature after the crushing phase, as a function of the different genetic origins of the olives. The process of phenolic compound solubilization into the oily phase was negatively influenced by the use of low temperature during the entire malaxation period for all the cultivars, whereas the volatile fraction showed an improvement in VOO flavor mainly due to the oil extracted from Canino olives.

Adjustment of Olive Fruit Temperature before Grinding for Olive Oil Extraction. Experimental Study and Pilot Plant Trials

Harvesting at high temperatures and bulk transport can negatively influence the quality of olives and lead to undesirable alterations in the extracted oil. Cooling the fruit in the field would be the most logical solution, but it means that the olives arrive too cold at the mill for immediate processing. In this work, the use of warm water in the washing tub to warm up the fruit before grinding instead of flash heat treatment on the paste was assessed in two experiments. In the first one, at the laboratory level, the temperature after milling was determined in three olive cultivars, previously stored at 5 or 10 °C, and then submerged at different water temperatures (25, 30, and 35 °C) for 15, 30, 45, and 60 s. In the second one, two batches of olives were cooled in the field at 5 °C and then conditioned with washing water to obtain a paste at the entrance of the pilot plant malaxer at 27 °C. The temperature of the olives was measured at five points from the discharging up to their entering, as paste, into the malaxer. The results demonstrated the feasibility of the method as the temperature of the ground olives was kept at the desired temperature (28 ± 1 °C). The trials highlight the potential for automating an even more precise adjustment of the temperature of the olives before milling once the washing tub is equipped with a safe heating system.

Differences and Correlations of Morphological Characteristics and Fatty Acid Profiles of Seeds of Toona sinensis

Toona sinensis (A.Juss.) M.Roem., a multi-purpose tree of Meliaceae, is widely distributed and intensively cultivated in Asia, yet its high yielding, lipid-rich seeds are rarely exploited. The present study systematically analyzed the differences and correlations of seed morphological characteristics and fatty acid (FA) profiles of 62 representative T. sinensis germplasms distributed across northern to southern China. T. sinensis seeds were rich in total FAs (TFA, 107.03-176.18 mg/g). Additionally, linoleic acid (54.69-100.59 mg/g), α-linolenic acid (ALA, 22.47-45.02 mg/g), oleic acid (OA, 5.12-23.94 mg/g), palmitic acid (6.87-14.14 mg/g), stearic acid (SA, 3.13-6.57 mg/g) and elaidic acid (1.70-2.88 mg/g) were the major FAs measured by GC/MS analysis. Size (average width of 3.94±0.01 mm and length of 5.79±0.02 mm) and mass (average thousand-seed weight of 10.52±0.17 g) were greater in T. sinensis seeds collected south than north of 30° latitude. These traits were also positively correlated with unsaturated FA content and negatively related to SA and saturated FA contents (P<0.05). Significant positive correlations were found between seed length and polyunsaturated FA (R² =0.370) and ALA levels (R² =0.296), as well as between thousand-seed weight and monounsaturated FAs (R² =0.309) and OA levels (R² =0.297) (P<0.05). Seventeen T. sinensis germplasms gathered by cluster analysis as cluster IV were determined as desirable for oil processing due to their higher TFA and ALA contents and greater seed size and mass than others. Generally, the wider, heavier, and especially longer seeds of T. sinensis contain much higher levels of FAs, especially ALA, and are the more promising sources for breeding and the oil processing industry.