Effects of olive maturation and stoning on quality indices and antioxidant content of extra virgin oils (cv. Coratina) during storage

Redox State Modulatory Activity and Cytotoxicity of Olea europaea L. (Oleaceae) Leaves Extract Enriched in Polyphenols Using Macroporous Resin

The food products derived from Olea europaea are a fundamental part of the Mediterranean diet, and their health-promoting effects are well known. In this study, we analyzed the phytochemical characteristics, the redox state modulatory activity, and the cytotoxic effect of an olive leaf aqueous extract enriched by macroporous resin on different tumor and normal cell lines (LNCaP, PC3, HFF-1). HPLC-DAD analysis, the Folin-Ciocalteu and aluminum chloride methods confirmed the qualitatively and quantitatively high content of phenolic compounds (130.02 ± 2.3 mg GAE/g extract), and a DPPH assay (IC50 = 100.00 ± 1.8 μg/mL), the related antioxidant activity. The biological investigation showed a significant cytotoxic effect, highlighted by an MTT test and the evident cellular morphological changes, on two prostate cancer cell lines. Remarkably, the extract was practically non-toxic on HFF-1 at the concentrations (100, 150, 300 µg/mL) and exposure times tested. Hence, the results are selective for tumor cells. The underlying cytotoxicity was associated with the decrease in ROS production (55% PC3, 42% LNCaP) and the increase in RSH levels (>50% PC3) and an LDH release assay (50% PC3, 40% LNCaP, established necrosis as the main cell death mechanism.

Fatty Acid and Phenolic Profiles of Virgin Olive Oils from Local and European Varieties Planted in Lebanon

In Lebanon, olive oil is an integral part of its history and culinary traditions. However, the quality of this product, originating from different growing regions of the country, is rarely addressed. The objectives of this study were to compare the fatty acids and phenolic profiles of virgin olive oils produced from two local and eight European varieties, and to use these profiles as a tool for their characterization. Seventy-six samples were collected from two olive-growing regions of Lebanon and at two harvesting times. Fatty acid composition was determined by gas chromatography with a flame ionization detector, total phenols was determined by spectrophotometry and individual phenols by high performance liquid chromatography with diode array detector. All samples were also analyzed using near infrared spectroscopy. The experimental data were collected in numerical matrices and treated by chemometric methods. The results showed the significant effect of the geographical origin, the olive variety and the harvesting time on the ripening and industrial yield of the olives and on the major fatty acids and phenols of olive oil. Moreover, the used chemometric methods allowed the discrimination of European olive varieties based on their high contents of oleic acid, oleacein and oleocanthal.

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.

Bioactive Compounds in Waste By-Products from Olive Oil Production: Applications and Structural Characterization by Mass Spectrometry Techniques

In recent years, a remarkable increase in olive oil consumption has occurred worldwide, favoured by its organoleptic properties and the growing awareness of its health benefits. Currently, olive oil production represents an important economic income for Mediterranean countries, where roughly 98% of the world production is located. Both the cultivation of olive trees and the production of industrial and table olive oil generate huge amounts of solid wastes and dark liquid effluents, including olive leaves and pomace and olive oil mill wastewaters. Besides representing an economic problem for producers, these by-products also pose serious environmental concerns, thus their partial reuse, like that of all agronomical production residues, represents a goal to pursue. This aspect is particularly important since the cited by-products are rich in bioactive compounds, which, once extracted, may represent ingredients with remarkable added value for food, cosmetic and nutraceutical industries. Indeed, they contain considerable amounts of valuable organic acids, carbohydrates, proteins, fibers, and above all, phenolic compounds, that are variably distributed among the different wastes, depending on the employed production process of olive oils and table olives and agronomical practices. Yet, extraction and recovery of bioactive components from selected by-products constitute a critical issue for their rational valorization and detailed identification and quantification are mandatory. The most used analytical methods adopted to identify and quantify bioactive compounds in olive oil by-products are based on the coupling between gas- (GC) or liquid chromatography (LC) and mass spectrometry (MS), with MS being the most useful and successful detection tool for providing structural information. Without derivatization, LC-MS with electrospray (ESI) or atmospheric pressure chemical (APCI) ionization sources has become one of the most relevant and versatile instrumental platforms for identifying phenolic bioactive compounds. In this review, the major LC-MS accomplishments reported in the literature over the last two decades to investigate olive oil processing by-products, specifically olive leaves and pomace and olive oil mill wastewaters, are described, focusing on phenolics and related compounds.

Olive Tree in Circular Economy as a Source of Secondary Metabolites Active for Human and Animal Health Beyond Oxidative Stress and Inflammation

Extra-virgin olive oil (EVOO) contains many bioactive compounds with multiple biological activities that make it one of the most important functional foods. Both the constituents of the lipid fraction and that of the unsaponifiable fraction show a clear action in reducing oxidative stress by acting on various body components, at concentrations established by the European Food Safety Authority's claims. In addition to the main product obtained by the mechanical pressing of the fruit, i.e., the EVOO, the residual by-products of the process also contain significant amounts of antioxidant molecules, thus potentially making the Olea europea L. an excellent example of the circular economy. In fact, the olive mill wastewaters, the leaves, the pomace, and the pits discharged from the EVOO production process are partially recycled in the nutraceutical and cosmeceutical fields also because of their antioxidant effect. This work presents an overview of the biological activities of these by-products, as shown by in vitro and in vivo assays, and also from clinical trials, as well as their main formulations currently available on the market.

NMR-based metabolomic study of Apulian Coratina extra virgin olive oil extracted with a combined ultrasound and thermal conditioning process in an industrial setting

The innovative combination of ultrasound (Us) with a thermal exchanger to produce high quality extra virgin olive oil (EVOO) was studied using Nuclear Magnetic Resonance (NMR) spectroscopy and multivariate analysis (MVA). Major and minor metabolomic components of Apulian Coratina EVOO obtained using the two methods were compared. Early and late olive ripening stages were also considered. An increased amount of polyphenols was found for EVOOs obtained using the Us with respect to the conventional method for both early and late ripening stages (900.8 ± 10.3 and 571.9 ± 9.9 mg/kg versus 645.1 ± 9.3 and 440.8 ± 10.4 mg/kg). NMR spectroscopy showed a significant increase (P < 0.05) in polyunsaturated fatty acids (PUFA) as well as in the tyrosol and hydroxytyrosol derivatives, such as oleocanthal, oleacein, and elenolic acid, for both ripening stages. In conclusion, NMR spectroscopy provides information about the metabolomic components of EVOOs to producers, while the Us process increases the levels of healthy bioactive components.

Addition of Olive Leaf Extract (OLE) for Producing Fortified Fresh Pasteurized Milk with An Extended Shelf Life

An olive leaf extract (OLE) has been tested in vitro for its antibacterial activity and ability to inhibit α-glucosidase enzyme. OLE was also evaluated for its potential, when added to pasteurized milk, to preserve nutritional parameters and to limit microbial growth, thus prolonging shelf life. In vitro assays demonstrated a strong antibacterial efficacy of OLE mainly against Bacillus cereus and the capacity to inhibit α-glucosidase enzyme (IC₅₀) when used at 0.2 mg oleuropein/mL. The milk fortification with OLE at 3.6 mg of oleuropein/mL of milk reduced total mesophilic bacteria at undetectable level after 6 d (expiration date) and by 1 log CFU/mL after 10 d. Moreover, OLE addition at 1.44 and 3.6 mg of oleuropein/mL of milk significantly reduced fat and lactose losses up to 10 d. The results motivate the use of the OLE to make a new functional milk with an extended shelf life.

Development of a centrifugal separator for grape marc: effect of the blade position and rotor speed on grape seed separation performance

The present study was conducted to find a method to separate grape seeds and soft solids from fresh marc at the end of wine-making processes. Interest in these by-products is growing owing to the high content of phytochemicals and other components useful in cosmetic and pharmaceutical industries. A prototype centrifugal separator was developed and its separation performance was evaluated. Four different reel speed rotations (480, 576, 687, and 842 rpm) and two different blade adjustments (Type-A blade with 1.5 mm and Type-B blade with 8.5 mm) were evaluated at the same mass flow rate (350 kg·h^-1). Results showed that the separation of seeds from the fresh grape marc using a centrifugal separator is possible and that this could be achieved by setting the optimal rotation speed of the reel (480 rpm) and establishing the best distance between the blades and the cylindrical separator (8.5 mm with TypeB blades).

Olive Leaf Addition Increases Olive Oil Nutraceutical Properties

The aim of the present research was to study the effects of olive leaf addition (0 and 3%) on the major antioxidants and the antioxidant activity of Neb Jmel and Oueslati olive oils. Olives and leaves of the two Tunisian varieties were harvested during the 2016/2017 crop season. Both leaves and oils were characterised for their concentrations in phenolics, tocopherols and antioxidant power. Other parameters such as free acidity, peroxide value, chlorophyll and carotenoid concentrations were also taken into consideration. Compared to Oueslati, the Neb Jmel oil showed a lower free acidity (50%) and peroxide value (5.6-fold), and higher chlorophyll (1.6-fold), total phenolics (1.3-fold), flavonoid (3-fold) and oleuropein derivative (1.5-fold) concentrations, in addition to an increased antioxidant activity (1.6-fold). Leaf addition promoted a significant increment in total chlorophyll, α-tocopherol and phenolics in both varieties, above all in Oueslati oil, due to a higher abundance of bioactive constituents in the corresponding leaves. In particular, chlorophyll and carotenoid concentrations reached values twice higher than in Neb Jmel leaves, and flavonoids and oleouperin derivatives were three-fold higher. This prevented the oxidation and the formation of peroxides, reducing the peroxide value of the fortified oil to the half. The results provide evidence on the performance of the Tunisian Neb Jmel and Oueslati varieties, showing that their oils present a chemical profile corresponding to the extra virgin olive oil category and that, after leaf addition, their nutritional value was improved.

De-stoning technology for improving olive oil nutritional and sensory features: The right idea at the wrong time

De-stoning technology has been introduced in the olive oil sector more than twenty years ago. It has not gained momentum because, sometimes, innovative ideas are not accepted since they are suggested at the wrong time or under the wrong circumstances. Virgin olive oil (VOO) is one of the most popular functional foods, mainly due to its antioxidant properties. These features, as well as other nutritional characteristics are generally enhanced by the de-stoning process. However, despite the improvement of the nutritional value, in the past the de-stoned oil didn't achieve marketing success mainly in relation to technological limitations (i.e. low oil yield). Only in recent years healthy properties became an element able to influence consumers' behavior, overcoming the limit of low oil yields and attracting the attention of olive oil producers. An analysis of the advantages, in terms of product quality and process sustainability, is given in this review. Here, for the first time, the fragmented results reported in literature are critically analyzed underlining the contradictions reported by different authors showing the main reasons for the unlucky fate of this technology in the industrial sector. In the final section the challenges, that future research must focus on, are presented, including emerging technologies in VOO processing. Literature data, for the first time discussed here exhaustively, show that de-stoning technology is a mechanical strategy useful to increase the nutritional and the sensory quality of the product. Moreover, it reduces the depletion of natural resources obtaining a selective crushing of the drupe by removing the stones from the olive paste so increasing the sustainability and efficiency of VOO extraction plants.

Bioactivity Improvement of Olea europaea Leaf Extract Biotransformed by Wickerhamomyces anomalus Enzymes

Olive leaves represent a quantitatively significant by-product of agroindustry. They are rich in phenols, mainly oleuropein, which can be hydrolyzed into several bioactive compounds, including hydroxytyrosol. In this study, water extract from olive leaves 'Biancolilla' was analyzed for polyphenol profile, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and protective effect on differentiated Caco-2 cells. The efficacy of two enzymatic treatments in promoting the release of bioactive phenols was investigated: a) enzymatic extract from Wickerhamomyces anomalus, characterized by β-glucosidase and esterase activities; b) commercial β-glucosidase. Composition and bioactivity of the resulting extracts were compared. The results showed that the yeast-treated extract presented hydroxytyrosol content and DPPH radical scavenging activity comparable to those obtained using commercial β-glucosidase; however, it was showed the additional presence of hydroxycinnamic acids. In experiments on Caco-2 cells, the leaf extracts promoted the recovery of cell membrane barrier at different minimum effective concentrations. The high specificity of W. anomalus enzymatic extract may represent an effective tool for the release of bioactive phenols from olive by-products.

Specification of a new de-stoner machine: evaluation of machining effects on olive paste's rheology and olive oil yield and quality

BACKGROUND

An industrial prototype of a partial de-stoner machine was specified, built and implemented in an industrial olive oil extraction plant. The partial de-stoner machine was compared to the traditional mechanical crusher to assess its quantitative and qualitative performance. The extraction efficiency of the olive oil extraction plant, olive oil quality, sensory evaluation and rheological aspects were investigated.

RESULTS

The results indicate that by using the partial de-stoner machine the extraction plant did not show statistical differences with respect to the traditional mechanical crushing. Moreover, the partial de-stoner machine allowed recovery of 60% of olive pits and the oils obtained were characterised by more marked green fruitiness, flavour and aroma than the oils produced using the traditional processing systems.

CONCLUSION

The partial de-stoner machine removes the limitations of the traditional total de-stoner machine, opening new frontiers for the recovery of pits to be used as biomass. Moreover, the partial de-stoner machine permitted a significant reduction in the viscosity of the olive paste. © 2016 Society of Chemical Industry.

Healthy virgin olive oil: a matter of bitterness

Virgin olive oil (VOO) is the pillar fat of Mediterranean diet. It is made from olive fruits and obtained by squeezing olives without any solvent extraction. Respect to the seed oils, an unique polar polyphenol-rich fraction gives VOO a bitter and pungent taste. The recent substantiation by European Food Safety Authority (EFSA) of a health claim for VOO polyphenols may represent an efficient stimulus to get the maximum health benefit from one of the most valuable traditional product of Mediterranean countries educating consumers to the relationship between the VOO bitterness and its health effect. Agronomical practices and new processing technology to avoid phenolic oxidation and hydrolysis and to enhance the aromatic components of the VOO have been developed and they can be used to modulate taste and flavor to diversify the products on the market. VOOs having high concentration of phenol compounds are bitter and pungent therefore many people do not consume them, thus loosing the health benefits related to their intake. In this paper, the chemist's and nutritionist's point of view has been considered to address possible strategies to overcome the existing gap between the quality perceived by consumer and that established by expert tasters. Educational campaigns emphasizing the bitter-health link for olive oils should be developed.

Phenols and Antioxidant Activity in Vitro and in Vivo of Aqueous Extracts Obtained by Ultrasound-Assisted Extraction from Artichoke By-Products

Artichoke by-products are rich in phenolic compounds although they represent a waste for the food industry. This paper examines the application of ultrasound-assisted extraction (UAE) for obtaining organic solvent-free extracts rich in nutraceuticals from artichoke scraps. Application of ultrasounds for 60 minutes on test samples, using water as a solvent, improved recovery of phenolic substances compared with untreated samples. Among the phenols detected by high performance liquid chromatography, 5- O-caffeoylquinic and 1,5-di- O-caffeoylquinic acids were identified. In vivo treatments of tobacco BY-2 cells with ultrasonic extracts consistently enhanced their antioxidant power, making the cells more resistant to heat stress. UAE applied to artichoke by-products, using water as a solvent, appears to be a powerful eco-friendly technique that can provide extracts rich in nutraceuticals and turn waste products into resources. The extracts could be advantageously utilized in the food industry to produce functional foods.

Working towards the development of innovative ultrasound equipment for the extraction of virgin olive oil

Malaxation has been recognized as one of the most critical points in the mechanical extraction process for virgin olive oil (VOO). It is a low and continuous kneading of olive paste at a carefully monitored temperature. Through this essential technological operation the small droplets of the oil formed during the milling merge into large drops that can be easily separated with a decanter centrifuge. During this technological phase, a complex and necessary bioprocess takes place in order to determine the quality and composition of the final product. The malaxer is a heat exchanger characterized by a low overall heat transfer coefficient because the ratio of surface area to volume is disadvantageous, so it is important to find an innovative technology to improve heat-exchange. As matter of fact, the malaxing step is the only discontinuous phase in a continuous extraction process. In the next future, the essential challenge of VOO industrial plant manufacturing sector is to design and build advanced machines in order to transform the discontinuous malaxing step in a continuous phase and improve the working capacity of the industrial plants. In order to reduce the malaxing time enhancing the quality of the product, two ultrasound-assisted virgin olive oil extraction processes were tested against the traditional method. The sonication treatment was applied on olives submerged in a water bath (before the crushing) and on olive paste (after the crushing). The ultrasound technology provides a reduction of the malaxing duration improving VOO yields and its minor compounds content. Better extractibility and higher minor compounds contents were obtained by sonicating the olives submerged in a water bath than olive paste. After experimental trials the results were employed to suggest innovative scaling up solutions of the process and new applications of ultrasounds in the VOO industry.

Extra virgin olive oil bitterness evaluation by sensory and chemical analyses

An experimental investigation was performed on blend extra virgin olive oils (EVOOs) from different cultivars and EVOO from different olive monovarieties (Coratina, Leccino, Maiatica, Ogliarola) with the aim to evaluate the possibility of estimating the perceived bitterness intensity by using chemical indices, such as the total phenol content and the compounds responsible for oil bitterness measured spectrophotometrically at 225 nm (K225 value), as bitterness predictors in different EVOO. Therefore, a bitterness predictive model, based on the relationship between the perceived bitterness intensity of the selected stimuli and the chosen chemicals parameters has been built and validated. The results indicated that the oil bitterness intensity could be satisfactorily predicted by using the K225 values of oil samples.